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Sample records for 3d pore network

  1. 3D imaging of soil pore network: two different approaches

    NASA Astrophysics Data System (ADS)

    Matrecano, M.; Di Matteo, B.; Mele, G.; Terribile, F.

    2009-04-01

    Pore geometry imaging and its quantitative description is a key factor for advances in the knowledge of physical, chemical and biological soil processes. For many years photos from flattened surfaces of undisturbed soil samples impregnated with fluorescent resin and from soil thin sections under microscope have been the only way available for exploring pore architecture at different scales. Earlier 3D representations of the internal structure of the soil based on not destructive methods have been obtained using medical tomographic systems (NMR and X-ray CT). However, images provided using such equipments, show strong limitations in terms of spatial resolution. In the last decade very good results have then been obtained using imaging from very expensive systems based on synchrotron radiation. More recently, X-ray Micro-Tomography has resulted the most widely applied being the technique showing the best compromise between costs, resolution and size of the images. Conversely, the conceptually simpler but destructive method of "serial sectioning" has been progressively neglected for technical problems in sample preparation and time consumption needed to obtain an adequate number of serial sections for correct 3D reconstruction of soil pore geometry. In this work a comparison between the two methods above has been carried out in order to define advantages, shortcomings and to point out their different potential. A cylindrical undisturbed soil sample 6.5cm in diameter and 6.5cm height of an Ap horizon of an alluvial soil showing vertic characteristics, has been reconstructed using both a desktop X-ray micro-tomograph Skyscan 1172 and the new automatic serial sectioning system SSAT (Sequential Section Automatic Tomography) set up at CNR ISAFOM in Ercolano (Italy) with the aim to overcome most of the typical limitations of such a technique. Image best resolution of 7.5 µm per voxel resulted using X-ray Micro CT while 20 µm was the best value using the serial sectioning

  2. Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

    NASA Astrophysics Data System (ADS)

    Perrier, E. M. A.; Bird, N. R. A.; Rieutord, T. B.

    2010-04-01

    Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a Critical Filtration Size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

  3. Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

    NASA Astrophysics Data System (ADS)

    Perrier, E. M. A.; Bird, N. R. A.; Rieutord, T. B.

    2010-10-01

    Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a critical filtration size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

  4. 3D pore-network analysis and permeability estimation of deformation bands hosted in carbonate grainstones.

    NASA Astrophysics Data System (ADS)

    Zambrano, Miller; Tondi, Emanuele; Mancini, Lucia; Trias, F. Xavier; Arzilli, Fabio; Lanzafame, Gabriele; Aibibula, Nijiati

    2016-04-01

    In porous rocks strain is commonly localized in narrow Deformation Bands (DBs), where the petrophysical properties are significantly modified with respect the pristine rock. As a consequence, DBs could have an important effect on production and development of porous reservoirs representing baffles zones or, in some cases, contribute to reservoir compartmentalization. Taking in consideration that the decrease of permeability within DBs is related to changes in the porous network properties (porosity, connectivity) and the pores morphology (size distribution, specific surface area), an accurate porous network characterization is useful for understanding both the effect of deformation banding on the porous network and their influence upon fluid flow through the deformed rocks. In this work, a 3D characterization of the microstructure and texture of DBs hosted in porous carbonate grainstones was obtained at the Elettra laboratory (Trieste, Italy) by using two different techniques: phase-contrast synchrotron radiation computed microtomography (micro-CT) and microfocus X-ray micro-CT. These techniques are suitable for addressing quantitative analysis of the porous network and implementing Computer Fluid Dynamics (CFD)experiments in porous rocks. Evaluated samples correspond to grainstones highly affected by DBs exposed in San Vito Lo Capo peninsula (Sicily, Italy), Favignana Island (Sicily, Italy) and Majella Mountain (Abruzzo, Italy). For the analysis, the data were segmented in two main components porous and solid phases. The properties of interest are porosity, connectivity, a grain and/or porous textural properties, in order to differentiate host rock and DBs in different zones. Permeability of DB and surrounding host rock were estimated by the implementation of CFD experiments, permeability results are validated by comparing with in situ measurements. In agreement with previous studies, the 3D image analysis and flow simulation indicate that DBs could be constitute

  5. Estimation of 3-D pore network coordination number of rocks from watershed segmentation of a single 2-D image

    NASA Astrophysics Data System (ADS)

    Rabbani, Arash; Ayatollahi, Shahab; Kharrat, Riyaz; Dashti, Nader

    2016-08-01

    In this study, we have utilized 3-D micro-tomography images of real and synthetic rocks to introduce two mathematical correlations which estimate the distribution parameters of 3-D coordination number using a single 2-D cross-sectional image. By applying a watershed segmentation algorithm, it is found that the distribution of 3-D coordination number is acceptably predictable by statistical analysis of the network extracted from 2-D images. In this study, we have utilized 25 volumetric images of rocks in order to propose two mathematical formulas. These formulas aim to approximate the average and standard deviation of coordination number in 3-D pore networks. Then, the formulas are applied for five independent test samples to evaluate the reliability. Finally, pore network flow modeling is used to find the error of absolute permeability prediction using estimated and measured coordination numbers. Results show that the 2-D images are considerably informative about the 3-D network of the rocks and can be utilized to approximate the 3-D connectivity of the porous spaces with determination coefficient of about 0.85 that seems to be acceptable considering the variety of the studied samples.

  6. Assessment of Image Processing and Resolution on Permeability and Drainage Simulations Through 3D Pore-networks Obtained Using X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Mills, G.; Willson, C. S.; Thompson, K. E.; Rivers, M. L.

    2013-12-01

    Typically, continuum-scale flow parameters are obtained through laboratory experiments. Over the past several years, image-based modeling, which is a direct simulation of flow through the structural arrangements of the voids and solids obtained using X-ray computed tomography (XCT) in a sample porous medium, has become a reliable technique for predicting certain flow parameters. Even though XCT is capable of resolving micron-level details, the voxel resolution of the reconstructed image is still dependent upon a number of factors, including the sample size, X-ray energy and XCT beamline setup. Thus, each imaging experiment requires a tradeoff between the sample size that can be imaged, the voxel resolution, and the length scale of the pore space that can be extracted. In addition, the geometric and topological properties of the void space and 3D pore network structure are dictated by the image processing and the choice of pore network generation method. In this research, image-based pore network models are used to quantitatively assess the impact of image resolution, image processing and the choice of pore network generation methods on simulated parameters. A 5 mm diameter and ~15 mm in length Berea sandstone core was scanned two times. First, a ~12 mm long section of the entire cross-section was scanned at 4.1 micron voxel resolution; next, a ~1.4 mm diameter and ~4.12 mm length section within the 1st domain was scanned at 1 micron voxel resolution. The resulting 3D datasets were filtered and segmented into solid and void space. The low resolution image was filtered and segmented using two different approaches in order to evaluate the potential of each approach in identifying the different solid phases in the original 16 bit dataset. A set of networks were created by varying the pore density on both the high and low resolution datasets in order to assess the impact of these factors on flow simulations. Single-phase permeability and a two-phase drainage pore

  7. Quantifying fluid distribution and phase connectivity with a simple 3D cubic pore network model constrained by NMR and MICP data

    NASA Astrophysics Data System (ADS)

    Xu, Chicheng; Torres-Verdín, Carlos

    2013-12-01

    A computer algorithm is implemented to construct 3D cubic pore networks that simultaneously honor nuclear magnetic resonance (NMR) and mercury injection capillary pressure (MICP) measurements on core samples. The algorithm uses discretized pore-body size distributions from NMR and pore-throat size versus incremental pore-volume fraction information from MICP as initial inputs. Both pore-throat radius distribution and body-throat correlation are iteratively refined to match percolation-simulated primary drainage capillary pressure with MICP data. It outputs a pore-throat radius distribution which is not directly measurable with either NMR or MICP. In addition, quasi-static fluid distribution and single-phase connectivity are quantified at each capillary pressure stage. NMR measurements on desaturating core samples are simulated from the quantitative fluid distribution in a gas-displacing-water drainage process and are verified with laboratory measurements. We invoke effective medium theory to quantify the single-phase connectivity in two-phase flow by simulating percolation in equivalent sub-pore-networks that consider the remaining fluid phase as solid cementation. Primary drainage relative permeability curves quantified from fluid distribution and phase connectivity show petrophysical consistency after applying a hydrated-water saturation correction. Core measurements of tight-gas sandstone samples from the Cotton Valley formation, East Texas, are used to verify the new algorithm.

  8. Anodization control for barrier-oxide thinning and 3D interconnected pores and direct electrodeposition of nanowire networks on native aluminium substrates.

    PubMed

    Gillette, Eleanor; Wittenberg, Stefanie; Graham, Lauren; Lee, Kwijong; Rubloff, Gary; Banerjee, Parag; Lee, Sang Bok

    2015-02-01

    Here we report a strategy for combining techniques for pore branching and barrier layer thinning to produce 3D porous anodized aluminum oxide films with direct ohmic contact to the native aluminum. This method provides an example of a rationally designed template which need not be removed from the aluminum, but which is also not constrained to traditional 2D pore geometry. We first demonstrate the barrier layer removal and pore branching techniques independently, and then combine them to produce free standing arrays of interconnected Ni nanostructures. Nickel nanostructures are deposited directly onto the aluminum to demonstrate the success of the structural modification, and showcase the potential for these films to be used as templates. This approach is the first to demonstrate the design and execution of multiple pore modification techniques in the same membrane, and demonstrates the first directly deposited 3D structures on aluminum substrates. PMID:25562070

  9. Arena3D: visualization of biological networks in 3D

    PubMed Central

    Pavlopoulos, Georgios A; O'Donoghue, Seán I; Satagopam, Venkata P; Soldatos, Theodoros G; Pafilis, Evangelos; Schneider, Reinhard

    2008-01-01

    Background Complexity is a key problem when visualizing biological networks; as the number of entities increases, most graphical views become incomprehensible. Our goal is to enable many thousands of entities to be visualized meaningfully and with high performance. Results We present a new visualization tool, Arena3D, which introduces a new concept of staggered layers in 3D space. Related data – such as proteins, chemicals, or pathways – can be grouped onto separate layers and arranged via layout algorithms, such as Fruchterman-Reingold, distance geometry, and a novel hierarchical layout. Data on a layer can be clustered via k-means, affinity propagation, Markov clustering, neighbor joining, tree clustering, or UPGMA ('unweighted pair-group method with arithmetic mean'). A simple input format defines the name and URL for each node, and defines connections or similarity scores between pairs of nodes. The use of Arena3D is illustrated with datasets related to Huntington's disease. Conclusion Arena3D is a user friendly visualization tool that is able to visualize biological or any other network in 3D space. It is free for academic use and runs on any platform. It can be downloaded or lunched directly from . Java3D library and Java 1.5 need to be pre-installed for the software to run. PMID:19040715

  10. Integration of Petrophysical Methods and 3D Printing Technology to Replicate Reservoir Pore Systems

    NASA Astrophysics Data System (ADS)

    Ishutov, S.; Hasiuk, F.; Gray, J.; Harding, C.

    2014-12-01

    Pore-scale imaging and modeling are becoming routine geoscience techniques of reservoir analysis and simulation in oil and gas industry. Three-dimensional printing may facilitate the transformation of pore-space imagery into rock models, which can be compared to traditional laboratory methods and literature data. Although current methodologies for rapid rock modeling and printing obscure many details of grain geometry, computed tomography data is one route to refine pore networks and experimentally test hypotheses related to rock properties, such as porosity and permeability. This study uses three-dimensional printing as a novel way of interacting with x-ray computed tomography data from reservoir core plugs based on digital modeling of pore systems in coarse-grained sandstones and limestones. The advantages of using artificial rocks as a proxy are to better understand the contributions of pore system characteristics at various scales to petrophysical properties in oil and gas reservoirs. Pore radii of reservoir sandstones used in this study range from 1 to 100s of microns, whereas the pore radii for limestones vary from 0.01 to 10s of microns. The resolution of computed tomography imaging is ~10 microns; the resolution of 3D digital printing used in the study varies from 2.5 to 300 microns. For this technology to be useful, loss of pore network information must be minimized in the course of data acquisition, modeling, and production as well as verified against core-scale measurements. The ultimate goal of this study is to develop a reservoir rock "photocopier" that couples 3D scanning and modeling with 3D printing to reproduce a) petrophyscially accurate copies of reservoir pore systems and b) digitally modified pore systems for testing hypotheses about reservoir flow. By allowing us to build porous media with known properties (porosity, permeability, surface area), technology will also advance our understanding of the tools used to measure these quantities (e

  11. Classification and quantification of pore shapes in sandstone reservoir rocks with 3-D X-ray micro-computed tomography

    NASA Astrophysics Data System (ADS)

    Schmitt, Mayka; Halisch, Matthias; Müller, Cornelia; Peres Fernandes, Celso

    2016-02-01

    Recent years have seen a growing interest in the characterization of the pore morphologies of reservoir rocks and how the spatial organization of pore traits affects the macro behavior of rock-fluid systems. With the availability of 3-D high-resolution imaging, such as x-ray micro-computed tomography (µ-CT), the detailed quantification of particle shapes has been facilitated by progress in computer science. Here, we show how the shapes of irregular rock particles (pores) can be classified and quantified based on binary 3-D images. The methodology requires the measurement of basic 3-D particle descriptors (length, width, and thickness) and a shape classification that involves the similarity of artificial objects, which is based on main pore network detachments and 3-D sample sizes. Two main pore components were identified from the analyzed volumes: pore networks and residual pore ganglia. A watershed algorithm was applied to preserve the pore morphology after separating the main pore networks, which is essential for the pore shape characterization. The results were validated for three sandstones (S1, S2, and S3) from distinct reservoirs, and most of the pore shapes were found to be plate- and cube-like, ranging from 39.49 to 50.94 % and from 58.80 to 45.18 % when the Feret caliper descriptor was investigated in a 10003 voxel volume. Furthermore, this study generalizes a practical way to correlate specific particle shapes, such as rods, blades, cuboids, plates, and cubes to characterize asymmetric particles of any material type with 3-D image analysis.

  12. Classification and quantification of pore shapes in sandstone reservoir rocks with 3-D X-ray micro-computed tomography

    NASA Astrophysics Data System (ADS)

    Schmitt, M.; Halisch, M.; Müller, C.; Fernandes, C. P.

    2015-12-01

    Recent years have seen a growing interest in the characterization of the pore morphologies of reservoir rocks and how the spatial organization of pore traits affects the macro behaviour of rock-fluid systems. With the availability of 3-D high-resolution imaging (e.g. μ-CT), the detailed quantification of particle shapes has been facilitated by progress in computer science. Here, we show how the shapes of irregular rock particles (pores) can be classified and quantified based on binary 3-D images. The methodology requires the measurement of basic 3-D particle descriptors and a shape classification that involves the similarity of artificial objects, which is based on main pore network detachments and 3-D sample sizes. The results were validated for three sandstones (S1, S2 and S3) from distinct reservoirs, and most of the pore shapes were found to be plate- and cube-like. Furthermore, this study generalizes a practical way to correlate specific particle shapes, such as rods, blades, cuboids, plates and cubes, to characterize asymmetric particles of any material type with 3-D image analysis.

  13. Pore-scale intermittent velocity structure underpinning anomalous transport through 3-D porous media

    NASA Astrophysics Data System (ADS)

    Kang, Peter K.; Anna, Pietro; Nunes, Joao P.; Bijeljic, Branko; Blunt, Martin J.; Juanes, Ruben

    2014-09-01

    We study the nature of non-Fickian particle transport in 3-D porous media by simulating fluid flow in the intricate pore space of real rock. We solve the full Navier-Stokes equations at the same resolution as the 3-D micro-CT (computed tomography) image of the rock sample and simulate particle transport along the streamlines of the velocity field. We find that transport at the pore scale is markedly anomalous: longitudinal spreading is superdiffusive, while transverse spreading is subdiffusive. We demonstrate that this anomalous behavior originates from the intermittent structure of the velocity field at the pore scale, which in turn emanates from the interplay between velocity heterogeneity and velocity correlation. Finally, we propose a continuous time random walk model that honors this intermittent structure at the pore scale and captures the anomalous 3-D transport behavior at the macroscale.

  14. 2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability

    SciTech Connect

    Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

    2013-09-03

    Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of

  15. Detection, 3-D positioning, and sizing of small pore defects using digital radiography and tracking

    NASA Astrophysics Data System (ADS)

    Lindgren, Erik

    2014-12-01

    This article presents an algorithm that handles the detection, positioning, and sizing of submillimeter-sized pores in welds using radiographic inspection and tracking. The possibility to detect, position, and size pores which have a low contrast-to-noise ratio increases the value of the nondestructive evaluation of welds by facilitating fatigue life predictions with lower uncertainty. In this article, a multiple hypothesis tracker with an extended Kalman filter is used to track an unknown number of pore indications in a sequence of radiographs as an object is rotated. Each pore is not required to be detected in all radiographs. In addition, in the tracking step, three-dimensional (3-D) positions of pore defects are calculated. To optimize, set up, and pre-evaluate the algorithm, the article explores a design of experimental approach in combination with synthetic radiographs of titanium laser welds containing pore defects. The pre-evaluation on synthetic radiographs at industrially reasonable contrast-to-noise ratios indicate less than 1% false detection rates at high detection rates and less than 0.1 mm of positioning errors for more than 90% of the pores. A comparison between experimental results of the presented algorithm and a computerized tomography reference measurement shows qualitatively good agreement in the 3-D positions of approximately 0.1-mm diameter pores in 5-mm-thick Ti-6242.

  16. Anisotropic thermal expansion of a 3D metal–organic framework with hydrophilic and hydrophobic pores

    SciTech Connect

    Kondo, Atsushi Maeda, Kazuyuki

    2015-01-15

    A 3D flexible metal–organic framework (MOF) with 1D hydrophilic and hydrophobic pores shows anisotropic thermal expansion with relatively large thermal expansion coefficient (α{sub a}=−21×10{sup −6} K{sup −1} and α{sub c}=79×10{sup −6} K{sup −1}) between 133 K and 383 K. Temperature change gives deformation of both pores, which expand in diameter and elongate in length on cooling and vice versa. The thermally induced structural change should be derived from a unique framework topology like “lattice fence”. Silica accommodation changes not only the nature of the MOF but also thermal responsiveness of the MOF. Since the hydrophobic pores in the material are selectively blocked by the silica, the MOF with the silica is considered as a hydrophilic microporous material. Furthermore, inclusion of silica resulted in a drastic pore contraction in diameter and anisotropically changed the thermal responsiveness of the MOF. - Graphical abstract: A 3D metal–organic framework with hydrophilic and hydrophobic pores shows anisotropic thermal expansion behavior. The influence of silica filler in the hydrophobic pore was investigated. - Highlights: • Thermally induced structural change of a 3D MOF with a lattice fence topology was investigated. • The structural change was analyzed by synchrotron X-ray diffraction patterns. • Temperature change induces anisotropic thermal expansion/contraction of the MOF. • Silica inclusion anisotropically changes the thermal responsiveness of the MOF.

  17. Tuning Cell Differentiation into a 3D Scaffold Presenting a Pore Shape Gradient for Osteochondral Regeneration.

    PubMed

    Di Luca, Andrea; Lorenzo-Moldero, Ivan; Mota, Carlos; Lepedda, Antonio; Auhl, Dietmar; Van Blitterswijk, Clemens; Moroni, Lorenzo

    2016-07-01

    Osteochondral regeneration remains nowadays a major problem since the outcome of current techniques is not satisfactory in terms of functional tissue formation and development. A possible solution is the combination of human mesenchymal stem cells (hMSCs) with additive manufacturing technologies to fabricate scaffolds with instructive properties. In this study, the differentiation of hMSCs within a scaffold presenting a gradient in pore shape is presented. The variation in pore shape is determined by varying the angle formed by the fibers of two consequent layers. The fiber deposition patterns are 0-90, which generate squared pores, 0-45, 0-30, and 0-15, that generate rhomboidal pores with an increasing major axis as the deposition angle decreases. Within the gradient construct, squared pores support a better chondrogenic differentiation whereas cells residing in the rhomboidal pores display a better osteogenic differentiation. When cultured under osteochondral conditions the trend in both osteogenic and chondrogenic markers is maintained. Engineering the pore shape, thus creating axial gradients in structural properties, seems to be an instructive strategy to fabricate functional 3D scaffolds that are able to influence hMSCs differentiation for osteochondral tissue regeneration. PMID:27109461

  18. 3D fast wavelet network model-assisted 3D face recognition

    NASA Astrophysics Data System (ADS)

    Said, Salwa; Jemai, Olfa; Zaied, Mourad; Ben Amar, Chokri

    2015-12-01

    In last years, the emergence of 3D shape in face recognition is due to its robustness to pose and illumination changes. These attractive benefits are not all the challenges to achieve satisfactory recognition rate. Other challenges such as facial expressions and computing time of matching algorithms remain to be explored. In this context, we propose our 3D face recognition approach using 3D wavelet networks. Our approach contains two stages: learning stage and recognition stage. For the training we propose a novel algorithm based on 3D fast wavelet transform. From 3D coordinates of the face (x,y,z), we proceed to voxelization to get a 3D volume which will be decomposed by 3D fast wavelet transform and modeled after that with a wavelet network, then their associated weights are considered as vector features to represent each training face . For the recognition stage, an unknown identity face is projected on all the training WN to obtain a new vector features after every projection. A similarity score is computed between the old and the obtained vector features. To show the efficiency of our approach, experimental results were performed on all the FRGC v.2 benchmark.

  19. Effects of pore size in 3-D fibrous matrix on human trophoblast tissue development.

    PubMed

    Ma, T; Li, Y; Yang, S T; Kniss, D A

    2000-12-20

    The effects of pore size in a 3-D polyethylene terephthalate (PET) nonwoven fibrous matrix on long-term tissue development of human trophoblast ED27 cells were studied. Thermal compression was used to modify the porosity and pore size of the PET matrix. The pore size distributions in PET matrices were quantified using a liquid extrusion method. Cell metabolic activities, estradiol production, and cell proliferation and differentiation were studied for ED27 cells cultured in the thermally compressed PET matrices with known pore structure characteristics. In general, metabolic activities and proliferation rate were higher initially for cultures grown in the low-porosity (LP) PET matrix (porosity of 0.849, average pore size of 30 microm in diameter) than those in the high-porosity (HP) matrix (porosity of 0.896, average pore size of 39 microm in diameter). However, 17beta-estradiol production and cell differentiation activity in the HP matrix surpassed those in the LP matrix after 12 days. The expression levels of cyclin B1 and p27kip1 in cells revealed progressively decreasing proliferation and increasing differentiation activities for cells grown in PET matrices. Also, difference in pore size controlled the cell spatial organization in the PET matrices and contributed to the tissue development in varying degrees of proliferation and differentiation. It was also found that cells grown on the 2-D surface behaved differently in cell cycle progression and did not show increased differentiation activities after growth had stopped and proliferation activities had lowered to a minimal level. The results from this study suggest that the 3-D cell organization guided by the tissue scaffold is important to tissue formation in vitro. PMID:11064329

  20. Benchmark Study of 3D Pore-scale Flow and Solute Transport Simulation Methods

    NASA Astrophysics Data System (ADS)

    Scheibe, T. D.; Yang, X.; Mehmani, Y.; Perkins, W. A.; Pasquali, A.; Schoenherr, M.; Kim, K.; Perego, M.; Parks, M. L.; Trask, N.; Balhoff, M.; Richmond, M. C.; Geier, M.; Krafczyk, M.; Luo, L. S.; Tartakovsky, A. M.

    2015-12-01

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that benchmark study to include additional models of the first type based on the immersed-boundary method (IMB), lattice Boltzmann method (LBM), and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries in the manner of PNMs has not been fully determined. We apply all five approaches (FVM-based CFD, IMB, LBM, SPH and PNM) to simulate pore-scale velocity distributions and nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The benchmark study was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence in a variety of pore-scale modeling methods, and motivates further development and application of pore-scale simulation methods.

  1. Intercomparison of 3D pore-scale flow and solute transport simulation methods

    DOE PAGESBeta

    Mehmani, Yashar; Schoenherr, Martin; Pasquali, Andrea; Perkins, William A.; Kim, Kyungjoo; Perego, Mauro; Parks, Michael L.; Balhoff, Matthew T.; Richmond, Marshall C.; Geier, Martin; et al

    2015-09-28

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based onmore » the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This paper provides support for

  2. Intercomparison of 3D pore-scale flow and solute transport simulation methods

    SciTech Connect

    Mehmani, Yashar; Schoenherr, Martin; Pasquali, Andrea; Perkins, William A.; Kim, Kyungjoo; Perego, Mauro; Parks, Michael L.; Balhoff, Matthew T.; Richmond, Marshall C.; Geier, Martin; Krafczyk, Manfred; Luo, Li -Shi; Tartakovsky, Alexandre M.; Yang, Xiaofan; Scheibe, Timothy D.; Trask, Nathaniel

    2015-09-28

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based on the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This paper provides support for confidence

  3. SOAX: A software for quantification of 3D biopolymer networks

    PubMed Central

    Xu, Ting; Vavylonis, Dimitrios; Tsai, Feng-Ching; Koenderink, Gijsje H.; Nie, Wei; Yusuf, Eddy; I-Ju Lee; Wu, Jian-Qiu; Huang, Xiaolei

    2015-01-01

    Filamentous biopolymer networks in cells and tissues are routinely imaged by confocal microscopy. Image analysis methods enable quantitative study of the properties of these curvilinear networks. However, software tools to quantify the geometry and topology of these often dense 3D networks and to localize network junctions are scarce. To fill this gap, we developed a new software tool called “SOAX”, which can accurately extract the centerlines of 3D biopolymer networks and identify network junctions using Stretching Open Active Contours (SOACs). It provides an open-source, user-friendly platform for network centerline extraction, 2D/3D visualization, manual editing and quantitative analysis. We propose a method to quantify the performance of SOAX, which helps determine the optimal extraction parameter values. We quantify several different types of biopolymer networks to demonstrate SOAX's potential to help answer key questions in cell biology and biophysics from a quantitative viewpoint. PMID:25765313

  4. 3-D target-based distributed smart camera network localization.

    PubMed

    Kassebaum, John; Bulusu, Nirupama; Feng, Wu-Chi

    2010-10-01

    For distributed smart camera networks to perform vision-based tasks such as subject recognition and tracking, every camera's position and orientation relative to a single 3-D coordinate frame must be accurately determined. In this paper, we present a new camera network localization solution that requires successively showing a 3-D feature point-rich target to all cameras, then using the known geometry of a 3-D target, cameras estimate and decompose projection matrices to compute their position and orientation relative to the coordinatization of the 3-D target's feature points. As each 3-D target position establishes a distinct coordinate frame, cameras that view more than one 3-D target position compute translations and rotations relating different positions' coordinate frames and share the transform data with neighbors to facilitate realignment of all cameras to a single coordinate frame. Compared to other localization solutions that use opportunistically found visual data, our solution is more suitable to battery-powered, processing-constrained camera networks because it requires communication only to determine simultaneous target viewings and for passing transform data. Additionally, our solution requires only pairwise view overlaps of sufficient size to see the 3-D target and detect its feature points, while also giving camera positions in meaningful units. We evaluate our algorithm in both real and simulated smart camera networks. In the real network, position error is less than 1 ('') when the 3-D target's feature points fill only 2.9% of the frame area. PMID:20679031

  5. Fabrication of 3D carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Laera, Anna Maria; Mirenghi, Luciana; Schioppa, Monica; Nobile, Concetta; Capodieci, Laura; Grazia Scalone, Anna; Di Benedetto, Francesca; Tapfer, Leander

    2016-08-01

    We report on the synthesis and characterization of a hyperbranched polymer englobing single-wall carbon nanotubes (SWCNTs). This new material was obtained by using SWCNTs functionalized with carboxylic groups as starting reagent. The acid groups were firstly converted in acyl chloride moieties and afterwards were bound to hexamethylenediamine (HMDA) via formation of amide functionality. The acquired spectra of attenuated total reflectance and the analysis performed through x-ray photoelectron spectroscopy confirmed the amide bond formation. The hyperbranched polymer characterization was completed by using scanning and transmission electron microscopy, thermo-gravimetric analysis and Raman spectroscopy. The electron microscopy analyses showed the formation of an amorphous polymeric material englobing a dense network of SWCNTs without phase segregation, demonstrating that the reaction with HMDA allows a reorganization of SWCNTs in a complex three-dimensional network.

  6. An Automated 3d Indoor Topological Navigation Network Modelling

    NASA Astrophysics Data System (ADS)

    Jamali, A.; Rahman, A. A.; Boguslawski, P.; Gold, C. M.

    2015-10-01

    Indoor navigation is important for various applications such as disaster management and safety analysis. In the last decade, indoor environment has been a focus of wide research; that includes developing techniques for acquiring indoor data (e.g. Terrestrial laser scanning), 3D indoor modelling and 3D indoor navigation models. In this paper, an automated 3D topological indoor network generated from inaccurate 3D building models is proposed. In a normal scenario, 3D indoor navigation network derivation needs accurate 3D models with no errors (e.g. gap, intersect) and two cells (e.g. rooms, corridors) should touch each other to build their connections. The presented 3D modeling of indoor navigation network is based on surveying control points and it is less dependent on the 3D geometrical building model. For reducing time and cost of indoor building data acquisition process, Trimble LaserAce 1000 as surveying instrument is used. The modelling results were validated against an accurate geometry of indoor building environment which was acquired using Trimble M3 total station.

  7. Representing geometric structures in 3D tomography soil images: Application to pore-space modeling

    NASA Astrophysics Data System (ADS)

    Monga, Olivier; Ndeye Ngom, Fatou; François Delerue, Jean

    2007-09-01

    Only in the last decade have geoscientists started to use 3D computed tomography (CT) images of soil for better understanding and modeling of soil properties. In this paper, we propose one of the first approaches to allow the definition and computation of stable (intrinsic) geometric representations of structures in 3D CT soil images. This addresses the open problem set by the description of volume shapes from discrete traces without any a priori information. The basic concept involves representing the volume shape by a piecewise approximation using simple volume primitives (bowls, cylinders, cones, etc.). This typical representation is assumed to optimize a criterion ensuring its stability. This criterion includes the representation scale, which characterizes the trade-off between the fitting error and the number of patches. We also take into account the preservation of topological properties of the initial shape: the number of connected components, adjacency relationships, etc. We propose an efficient computation method for this piecewise approximation using cylinders or bowls. For cylinders, we use optimal region growing in a valuated adjacency graph that represents the primitives and their adjacency relationships. For bowls, we compute a minimal set of Delaunay spheres recovering the skeleton. Our method is applied to modeling of a coarse pore space extracted from 3D CT soil images. The piecewise bowls approximation gives a geometric formalism corresponding to the intuitive notion of pores and also an efficient way to compute it. This geometric and topological representation of coarse pore space can be used, for instance, to simulate biological activity in soil.

  8. Construction of programmable interconnected 3D microfluidic networks

    NASA Astrophysics Data System (ADS)

    Hunziker, Patrick R.; Wolf, Marc P.; Wang, Xueya; Zhang, Bei; Marsch, Stephan; Salieb-Beugelaar, Georgette B.

    2015-02-01

    Microfluidic systems represent a key-enabling platform for novel diagnostic tools for use at the point-of-care in clinical contexts as well as for evolving single cell diagnostics. The design of 3D microfluidic systems is an active field of development, but construction of true interconnected 3D microfluidic networks is still a challenge, in particular when the goal is rapid prototyping, accurate design and flexibility. We report a novel approach for the construction of programmable 3D microfluidic systems consisting of modular 3D template casting of interconnected threads to allow user-programmable flow paths and examine its structural characteristics and its modular function. To overcome problems with thread template casting reported in the literature, low-surface-energy polymer threads were used, that allow solvent-free production. Connected circular channels with excellent roundness and low diameter variability were created. Variable channel termination allowed programming a flow path on-the-fly, thus rendering the resulting 3D microfluidic systems highly customizable even after production. Thus, construction of programmable/reprogrammable fully 3D microfluidic systems by template casting of a network of interconnecting threads is feasible, leads to high-quality and highly reproducible, complex 3D geometries.

  9. 3D quantitative phase imaging of neural networks using WDT

    NASA Astrophysics Data System (ADS)

    Kim, Taewoo; Liu, S. C.; Iyer, Raj; Gillette, Martha U.; Popescu, Gabriel

    2015-03-01

    White-light diffraction tomography (WDT) is a recently developed 3D imaging technique based on a quantitative phase imaging system called spatial light interference microscopy (SLIM). The technique has achieved a sub-micron resolution in all three directions with high sensitivity granted by the low-coherence of a white-light source. Demonstrations of the technique on single cell imaging have been presented previously; however, imaging on any larger sample, including a cluster of cells, has not been demonstrated using the technique. Neurons in an animal body form a highly complex and spatially organized 3D structure, which can be characterized by neuronal networks or circuits. Currently, the most common method of studying the 3D structure of neuron networks is by using a confocal fluorescence microscope, which requires fluorescence tagging with either transient membrane dyes or after fixation of the cells. Therefore, studies on neurons are often limited to samples that are chemically treated and/or dead. WDT presents a solution for imaging live neuron networks with a high spatial and temporal resolution, because it is a 3D imaging method that is label-free and non-invasive. Using this method, a mouse or rat hippocampal neuron culture and a mouse dorsal root ganglion (DRG) neuron culture have been imaged in order to see the extension of processes between the cells in 3D. Furthermore, the tomogram is compared with a confocal fluorescence image in order to investigate the 3D structure at synapses.

  10. Extreme low thermal conductivity in nanoscale 3D Si phononic crystal with spherical pores.

    PubMed

    Yang, Lina; Yang, Nuo; Li, Baowen

    2014-01-01

    In this work, we propose a nanoscale three-dimensional (3D) Si phononic crystal (PnC) with spherical pores, which can reduce the thermal conductivity of bulk Si by a factor up to 10,000 times at room temperature. Thermal conductivity of Si PnCs depends on the porosity, for example, the thermal conductivity of Si PnCs with porosity 50% is 300 times smaller than that of bulk Si. The phonon participation ratio spectra demonstrate that more phonons are localized as the porosity increases. The thermal conductivity is insensitive to the temperature changes from room temperature to 1100 K. The extreme-low thermal conductivity could lead to a larger value of ZT than unity as the periodic structure affects very little the electric conductivity. PMID:24559126

  11. On the application of focused ion beam nanotomography in characterizing the 3D pore space geometry of Opalinus clay

    NASA Astrophysics Data System (ADS)

    Keller, Lukas M.; Holzer, Lorenz; Wepf, Roger; Gasser, Philippe; Münch, Beat; Marschall, Paul

    The evaluation and optimization of radioactive disposal systems requires a comprehensive understanding of mass transport processes. Among others, mass transport in porous geomaterials depends crucially on the topology and geometry of the pore space. Thus, understanding the mechanism of mass transport processes ultimately requires a 3D characterization of the pore structure. Here, we demonstrate the potential of focused ion beam nanotomography (FIB-nT) in characterizing the 3D geometry of pore space in clay rocks, i.e. Opalinus clay. In order to preserve the microstructure and to reduce sample preparation artefacts we used high pressure freezing and subsequent freeze drying to prepare the samples. Resolution limitations placed the lower limit in pore radii that can be analyzed by FIB-nT to about 10-15 nm. Image analysis and the calculation of pore size distribution revealed that pores with radii larger than 15 nm are related to a porosity of about 3 vol.%. To validate the method, we compared the pores size distribution obtained by FIB-nT with the one obtained by N 2 adsorption analysis. The latter yielded a porosity of about 13 vol.%. This means that FIB-nT can describe around 20-30% of the total pore space. For pore radii larger than 15 nm the pore size distribution obtained by FIB-nT and N 2 adsorption analysis were in good agreement. This suggests that FIB-nT can provide representative data on the spatial distribution of pores for pore sizes in the range of about 10-100 nm. Based on the spatial analysis of 3D data we extracted information on the spatial distribution of pore space geometrical properties.

  12. Pore networks in continental and marine mudstones: Characteristics and controls on sealing behavior

    USGS Publications Warehouse

    Heath, J.E.; Dewers, T.A.; McPherson, B.J.O.L.; Petrusak, R.; Chidsey, T.C.; Rinehart, A.J.; Mozley, P.S.

    2011-01-01

    Mudstone pore networks are strong modifiers of sedimentary basin fluid dynamics and have a critical role in the distribution of hydrocarbons and containment of injected fluids. Using core samples from continental and marine mudstones, we investigate properties of pore types and networks from a variety of geologic environments, together with estimates of capillary beam- scanning electron microscopy, suggest seven dominant mudstone pore types distinguished by geometry and connectivity. A dominant planar pore type occurs in all investigated mudstones and generally has high coordination numbers (i.e., number of neighboring connected pores). Connected networks of pores of this type contribute to high mercury capillary pressures due to small pore throats at the junctions of connected pores and likely control most matrix transport in these mudstones. Other pore types are related to authigenic (e.g., replacement or pore-lining precipitation) clay minerals and pyrite nodules; pores in clay packets adjacent to larger, more competent clastic grains; pores in organic phases; and stylolitic and microfracture-related pores. Pores within regions of authigenic clay minerals often form small isolated networks (<3 ??m). Pores in stringers of organic phases occur as tubular pores or slit- and/or sheet-like pores. These form short, connected lengths in 3D reconstructions, but appear to form networks no larger than a few microns in size. Sealing efficiency of the studied mudstones increases with greater distal depositional environments and greater maximum depth of burial. ?? 2011 Geological Society of America.

  13. Constructing 3D microtubule networks using holographic optical trapping

    PubMed Central

    Bergman, J.; Osunbayo, O.; Vershinin, M.

    2015-01-01

    Developing abilities to assemble nanoscale structures is a major scientific and engineering challenge. We report a technique which allows precise positioning and manipulation of individual rigid filaments, enabling construction of custom-designed 3D filament networks. This approach uses holographic optical trapping (HOT) for nano-positioning and microtubules (MTs) as network building blocks. MTs are desirable engineering components due to their high aspect ratio, rigidity, and their ability to serve as substrate for directed nano-transport, reflecting their roles in the eukaryotic cytoskeleton. The 3D architecture of MT cytoskeleton is a significant component of its function, however experimental tools to study the roles of this geometric complexity in a controlled environment have been lacking. We demonstrate the broad capabilities of our system by building a self-supporting 3D MT-based nanostructure and by conducting a MT-based transport experiment on a dynamically adjustable 3D MT intersection. Our methodology not only will advance studies of cytoskeletal networks (and associated processes such as MT-based transport) but will also likely find use in engineering nanostructures and devices. PMID:26657337

  14. Understanding North Texas Seismicity: A Joint Analysis of Seismic Data and 3D Pore Pressure Modeling

    NASA Astrophysics Data System (ADS)

    DeShon, H. R.; Hornbach, M. J.; Ellsworth, W. L.; Oldham, H. R.; Hayward, C.; Stump, B. W.; Frohlich, C.; Olson, J. E.; Luetgert, J. H.

    2014-12-01

    In November 2013, a series of earthquakes began along a mapped ancient fault system near Azle, Texas. The Azle events are the third felt earthquake sequence in the Fort Worth (Barnett Shale) Basin since 2008, and several production and injection wells in the area are drilled to depths near the recent seismic activity. Understanding if and/or how injection and removal of fluids in the crystalline crust reactivates faults have important implications for seismology, the energy industry, and society. We assessed whether the Azle earthquakes were induced using a joint analysis of the earthquake data, subsurface geology and fault structure, and 3D pore pressure modeling. Using a 12-station temporary seismic deployment, we have recorded and located >300 events large enough to be recorded on multiple stations and 1000s of events during periods of swarm activity. High-resolution locations and focal mechanisms indicate that events occurred on NE-SW trending, steeply dipping normal faults associated with the southern end of the Newark East Fault Zone with hypocenters between 2-8 km depth. We considered multiple causes that might have changed stress along this system. Earthquakes resulting from natural processes, though perhaps unlikely in this historically inactive region, can be neither ruled out nor confirmed due to lack of information on the natural stress state of these faults. Analysis of lake and groundwater variations near Azle showed that no significant stress changes occurred prior to or during the earthquake sequence. In contrast, analysis of pore-pressure models shows that the combination of formation water production and wastewater injection near the fault could have caused pressure increases that induced earthquakes on near-critically stressed faults.

  15. Long term effects of CO2 on 3-D pore structure and 3-D phase distribution in reservoir sandstones from the Green River well (Utah, USA)

    NASA Astrophysics Data System (ADS)

    Barnhoorn, Auke; Kisoensingh, Shailesh

    2014-05-01

    Reservoir sandstones and cap rocks from the Green River area in Utah (USA) have been naturally exposed to CO2 fluids for hundreds of thousands of years, leading to compositional and microstructural alterations of the rocks. A 300m long section of this section of these Green river reservoir and cap rocks has been cored in 2012. Here, results of a high-resolution micro X-ray tomography study of a suite of samples from the well are reported detailing the 3D pore structure and phase distribution changes due to long term CO2 exposure. The reservoir sandstones from the Green River well (Utah) reveal the presence of various degrees of carbonate precipitation in the pores. Both reservoir sandstones (the shallower Entrada Formation and the deeper Navajo Formation) show variations in carbonate content and porosity structure. The Entrada sandstone exhibits widespread carbonate precipitation (up to 60% of infill of the original porosity), with the largest amount of carbonates at the boundary with the underlying Carmel cap rock. In an interval of a meter from the contact, carbonate precipitation decreases sharply till ~20%. The porosity is significantly reduced in the lowest 1 meter. The reduction in porosity lead to a reduction in pore connectivity and thereby permeability by the long-term CO2 exposure. On the other hand the Navajo sandstone shows predominantly only isolated spots of carbonate precipitation (up to 20% of the original porosity). Widespread carbonate precipitation is absent in the Navajo reservoir sandstone samples. Because carbonate precipitation is not present throughout, the large-scale permeability of the formation is likely not significantly affected by the CO2 exposure. The results show how the 3D distribution of the phases and the 3D shapes of the pores are affected by long term CO2 exposure and can be used as an example for potential changes to be expected in reservoir sandstones due to CO2 storage in future CO2 sequestration endeavours.

  16. An algorithm for studying rigidity in disordered 3D networks

    NASA Astrophysics Data System (ADS)

    Chubynsky, M. V.; Thorpe, M. F.

    2004-03-01

    Some physical systems, such as covalent glasses and proteins, can be modeled as elastic networks, by dividing the interactions between particles into strong and weak, representing the former as constraints and neglecting the latter. For low enough connectivities, motions maintaining the constraints and thus having zero energy cost are possible. The goal of rigidity analysis is finding the number of such zero energy modes, the rigid clusters and flexible joints between them, as well as stressed bonds. For a certain class of networks there is a very fast graph-theoretical algorithm (the Pebble Game) for doing this analysis, but for more general networks, there are known counterexamples. While generalizing the Pebble Game is the ultimate goal, we propose a slower algorithm capable of doing all the same analyses as the Pebble Game but applicable to any networks. We discuss the applications of this algorithm to specific examples of 3D networks, such as diluted central force lattices, colloidal glasses and proteins.

  17. Wetting Hierarchy in Oleophobic 3D Electrospun Nanofiber Networks.

    PubMed

    Stachewicz, Urszula; Bailey, Russell J; Zhang, Hao; Stone, Corinne A; Willis, Colin R; Barber, Asa H

    2015-08-01

    Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance in many applications including filtration and liquid-repellent textiles. The relationship between intrinsic nanofiber properties, including surface characteristics, and extrinsic nanofibrous network organization on resultant wetting characteristics of the nanofiber network is shown in this work. Novel 3D imaging exploiting focused ion beam (FIB) microscopy and cryo-scanning electron microscopy (cryo-SEM) highlights a wetting hierarchy that defines liquid interactions with the network. Specifically, small length scale partial wetting between individual electrospun nanofibers and low surface tension liquids, measured both using direct SEM visualization and a nano Wilhelmy balance approach, provides oleophobic surfaces due to the high porosity of electrospun nanofiber networks. These observations conform to a metastable Cassie-Baxter regime and are important in defining general rules for understanding the wetting behavior between fibrous solids and low surface tension liquids for omniphobic functionality. PMID:26176304

  18. Colloid-guided assembly of oriented 3D neuronal networks

    PubMed Central

    Pautot, Sophie; Wyart, Claire; Isacoff, Ehud Y

    2009-01-01

    A central challenge in neuroscience is to understand the formation and function of three-dimensional (3D) neuronal networks. In vitro studies have been mainly limited to measurements of small numbers of neurons connected in two dimensions. Here we demonstrate the use of colloids as moveable supports for neuronal growth, maturation, transfection and manipulation, where the colloids serve as guides for the assembly of controlled 3D, millimeter-sized neuronal networks. Process growth can be guided into layered connectivity with a density similar to what is found in vivo. The colloidal superstructures are optically transparent, enabling remote stimulation and recording of neuronal activity using layer-specific expression of light-activated channels and indicator dyes. The modular approach toward in vitro circuit construction provides a stepping stone for applications ranging from basic neuroscience to neuron-based screening of targeted drugs. PMID:18641658

  19. Characterization of Pore Defects and Fatigue Cracks in Die Cast AM60 Using 3D X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Yang, Zhuofei; Kang, Jidong; Wilkinson, David S.

    2015-08-01

    AM60 high pressure die castings have been used in automobile applications to reduce the weight of vehicles. However, the pore defects that are inherent in die casting may negatively affect mechanical properties, especially the fatigue properties. Here we have studied damage ( e.g., pore defects, fatigue cracks) during strained-controlled fatigue using 3-dimensional X-ray computed tomography (XCT). The fatigue test was interrupted every 2000 cycles and the specimen was removed to be scanned using a desktop micro-CT system. XCT reveals pore defects, cracks, and fracture surfaces. The results show that pores can be accurately measured and modeled in 3D. Defect bands are found to be made of pores under 50 µm (based on volume-equivalent sphere diameter). Larger pores are randomly distributed in the region between the defect bands. Observation of fatigue cracks by XCT is performed in three ways such that the 3D model gives the best illustration of crack-porosity interaction while the other two methods, with the cracks being viewed on transverse or longitudinal cross sections, have better detectability on crack initiation and crack tip observation. XCT is also of value in failure analysis on fracture surfaces. By assessing XCT data during fatigue testing and observing fracture surfaces on a 3D model, a better understanding on the crack initiation, crack-porosity interaction, and the morphology of fracture surface is achieved.

  20. 3-D flame temperature field reconstruction with multiobjective neural network

    NASA Astrophysics Data System (ADS)

    Wan, Xiong; Gao, Yiqing; Wang, Yuanmei

    2003-02-01

    A novel 3-D temperature field reconstruction method is proposed in this paper, which is based on multiwavelength thermometry and Hopfield neural network computed tomography. A mathematical model of multi-wavelength thermometry is founded, and a neural network algorithm based on multiobjective optimization is developed. Through computer simulation and comparison with the algebraic reconstruction technique (ART) and the filter back-projection algorithm (FBP), the reconstruction result of the new method is discussed in detail. The study shows that the new method always gives the best reconstruction results. At last, temperature distribution of a section of four peaks candle flame is reconstructed with this novel method.

  1. 3D Actin Network Centerline Extraction with Multiple Active Contours

    PubMed Central

    Xu, Ting; Vavylonis, Dimitrios; Huang, Xiaolei

    2013-01-01

    Fluorescence microscopy is frequently used to study two and three dimensional network structures formed by cytoskeletal polymer fibers such as actin filaments and actin cables. While these cytoskeletal structures are often dilute enough to allow imaging of individual filaments or bundles of them, quantitative analysis of these images is challenging. To facilitate quantitative, reproducible and objective analysis of the image data, we propose a semi-automated method to extract actin networks and retrieve their topology in 3D. Our method uses multiple Stretching Open Active Contours (SOACs) that are automatically initialized at image intensity ridges and then evolve along the centerlines of filaments in the network. SOACs can merge, stop at junctions, and reconfigure with others to allow smooth crossing at junctions of filaments. The proposed approach is generally applicable to images of curvilinear networks with low SNR. We demonstrate its potential by extracting the centerlines of synthetic meshwork images, actin networks in 2D Total Internal Reflection Fluorescence Microscopy images, and 3D actin cable meshworks of live fission yeast cells imaged by spinning disk confocal microscopy. Quantitative evaluation of the method using synthetic images shows that for images with SNR above 5.0, the average vertex error measured by the distance between our result and ground truth is 1 voxel, and the average Hausdorff distance is below 10 voxels. PMID:24316442

  2. 3D Filament Network Segmentation with Multiple Active Contours

    NASA Astrophysics Data System (ADS)

    Xu, Ting; Vavylonis, Dimitrios; Huang, Xiaolei

    2014-03-01

    Fluorescence microscopy is frequently used to study two and three dimensional network structures formed by cytoskeletal polymer fibers such as actin filaments and microtubules. While these cytoskeletal structures are often dilute enough to allow imaging of individual filaments or bundles of them, quantitative analysis of these images is challenging. To facilitate quantitative, reproducible and objective analysis of the image data, we developed a semi-automated method to extract actin networks and retrieve their topology in 3D. Our method uses multiple Stretching Open Active Contours (SOACs) that are automatically initialized at image intensity ridges and then evolve along the centerlines of filaments in the network. SOACs can merge, stop at junctions, and reconfigure with others to allow smooth crossing at junctions of filaments. The proposed approach is generally applicable to images of curvilinear networks with low SNR. We demonstrate its potential by extracting the centerlines of synthetic meshwork images, actin networks in 2D TIRF Microscopy images, and 3D actin cable meshworks of live fission yeast cells imaged by spinning disk confocal microscopy.

  3. Large optical 3D MEMS switches in access networks

    NASA Astrophysics Data System (ADS)

    Madamopoulos, Nicholas; Kaman, Volkan; Yuan, Shifu; Jerphagnon, Olivier; Helkey, Roger; Bowers, John E.

    2007-09-01

    Interest is high among residential customers and businesses for advanced, broadband services such as fast Internet access, electronic commerce, video-on-demand, digital broadcasting, teleconferencing and telemedicine. In order to satisfy such growing demand of end-customers, access technologies such as fiber-to-the-home/building (FTTH/B) are increasingly being deployed. Carriers can reduce maintenance costs, minimize technology obsolescence and introduce new services easily by reducing active elements in the fiber access network. However, having a passive optical network (PON) also introduces operational and maintenance challenges. Increased diagnostic monitoring capability of the network becomes a necessity as more and more fibers are provisioned to deliver services to the end-customers. This paper demonstrates the clear advantages that large 3D optical MEMS switches offer in solving these access network problems. The advantages in preventative maintenance, remote monitoring, test and diagnostic capability are highlighted. The low optical insertion loss for all switch optical connections of the switch enables the monitoring, grooming and serving of a large number of PON lines and customers. Furthermore, the 3D MEMS switch is transparent to optical wavelengths and data formats, thus making it easy to incorporate future upgrades, such higher bit rates or DWDM overlay to a PON.

  4. 3D Photofixation Lithography in Diels–Alder Networks

    PubMed Central

    Adzima, Brian J.; Kloxin, Christopher J.; DeForest, Cole A.; Anseth, Kristi S.

    2013-01-01

    3D structures were written and developed in a crosslinked polymer initially formed by a Diels–Alder reaction. Unlike conventional liquid resists, small features cannot sediment, as the reversible crosslinks function as a support, and the modulus of the material is in the MPa range at room temperature. The support structure, however, can be easily removed by heating the material which depolymerizes the polymer into a mixture of low-viscosity monomers. Complex shapes were written into the polymer network using two-photon techniques to spatially control the photoinitiation and subsequent thiol–ene reaction to selectively convert the Diels–Alder adducts into irreversible crosslinks. PMID:23080017

  5. FROMS3D: New Software for 3-D Visualization of Fracture Network System in Fractured Rock Masses

    NASA Astrophysics Data System (ADS)

    Noh, Y. H.; Um, J. G.; Choi, Y.

    2014-12-01

    A new software (FROMS3D) is presented to visualize fracture network system in 3-D. The software consists of several modules that play roles in management of borehole and field fracture data, fracture network modelling, visualization of fracture geometry in 3-D and calculation and visualization of intersections and equivalent pipes between fractures. Intel Parallel Studio XE 2013, Visual Studio.NET 2010 and the open source VTK library were utilized as development tools to efficiently implement the modules and the graphical user interface of the software. The results have suggested that the developed software is effective in visualizing 3-D fracture network system, and can provide useful information to tackle the engineering geological problems related to strength, deformability and hydraulic behaviors of the fractured rock masses.

  6. Pore size and LbL chitosan coating influence mesenchymal stem cell in vitro fibrosis and biomineralization in 3D porous poly(epsilon-caprolactone) scaffolds.

    PubMed

    Mehr, Nima Ghavidel; Li, Xian; Chen, Gaoping; Favis, Basil D; Hoemann, Caroline D

    2015-07-01

    Poly(epsilon-caprolactone) (PCL) is a hydrophobic bioplastic under development for bone tissue engineering applications. Limited information is available on the role of internal geometry and cell-surface attachment on osseous integration potential. We tested the hypothesis that human bone marrow mesenchymal stem cells (MSCs) deposit more mineral inside porous 3D PCL scaffolds with fully interconnected 84 or 141 µm pores, when the surfaces are coated with chitosan via Layer-by-Layer (LbL)-deposited polyelectrolytes. Freshly trypsinized MSCs were seeded on PCL 3D cylinders using a novel static cold seeding method in 2% serum to optimally populate all depths of the scaffold discs, followed by 10 days of culture in proliferation medium and 21 additional days in osteogenic medium. MSCs were observed by SEM and histology to spread faster and to proliferate more on chitosan-coated pore surfaces. Most pores, with or without chitosan, became filled by collagen networks sparsely populated with fibroblast-like cells. After 21 days of culture in osteogenic medium, sporadic matrix mineralization was detected histologically and by micro-CT in highly cellular surface layers that enveloped all scaffolds and in cell aggregates in 141 µm pores near the edges. LbL-chitosan promoted punctate mineral deposition on the surfaces of 84 µm pores (p < 0.05 vs. PCL-only) but not the 141 µm pores. This study revealed that LbL-chitosan coatings are sufficient to promote MSC attachment to PCL but only enhance mineral formation in 84 µm pores, suggesting a potential inhibitory role for MSC-derived fibroblasts in osteoblast terminal differentiation. PMID:25504184

  7. Simultaneous optimization of surface chemistry and pore morphology of 3D graphene-sulfur cathode via multi-ion modulation

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Cheng, Shuang; Li, Wanfei; Zhang, Su; Li, Hongfei; Zheng, Zhaozhao; Li, Fujin; Shi, Liyi; Lin, Hongzhen; Zhang, Yuegang

    2016-07-01

    Lithium/sulfur (Li/S) battery is a promising next-generation energy storage system owing to its high theoretical energy density. However, for practical use there remains some key problems to be solved, such as low active material utilization and rapid capacity fading, especially at high areal sulfur loadings. Here, we report a facile one-pot method to prepare porous three-dimensional nitrogen, sulfur-codoped graphene through hydrothermal reduction of graphene oxide with multi-ion mixture modulation. We show solid evidence that the results of multi-ion mixture modulation can not only improve the surface affinity of the nanocarbons to polysulfides, but also alter their assembling manner and render the resultant 3D network a more favorable pore morphology for accommodating and confining sulfur. It also had an excellent rate performance and cycling stability, showing an initial capacity of 1304 mA h g-1 at 0.05C, 613 mA h g-1 at 5C and maintaining a reversible capacity of 462 mA h g-1 after 1500 cycles at 2C with capacity fading as low as 0.028% per cycle. Moreover, a high areal capacity of 5.1 mA h cm-2 at 0.2C is achieved at an areal sulfur loading of 6.3 mg cm-2, which are the best values reported so far for dual-doped sulfur cathodes.

  8. Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

    PubMed Central

    Pak, Tannaz; Butler, Ian B.; Geiger, Sebastian; van Dijke, Marinus I. J.; Sorbie, Ken S.

    2015-01-01

    Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces. PMID:25646491

  9. Modulating mechanical behaviour of 3D-printed cartilage-mimetic PCL scaffolds: influence of molecular weight and pore geometry.

    PubMed

    Olubamiji, Adeola D; Izadifar, Zohreh; Si, Jennifer L; Cooper, David M L; Eames, B Frank; Chen, Daniel X B

    2016-06-01

    Three-dimensional (3D)-printed poly(ε)-caprolactone (PCL)-based scaffolds are increasingly being explored for cartilage tissue engineering (CTE) applications. However, ensuring that the mechanical properties of these PCL-based constructs are comparable to that of articular cartilage that they are meant to regenerate is an area that has been under-explored. This paper presents the effects of PCL's molecular weight (MW) and scaffold's pore geometric configurations; strand size (SZ), strand spacing (SS), and strand orientation (SO), on mechanical properties of 3D-printed PCL scaffolds. The results illustrate that MW has significant effect on compressive moduli and yield strength of 3D-printed PCL scaffolds. Specifically, PCL with MW of 45 K was a more feasible choice for fabrication of visco-elastic, flexible and load-bearing PCL scaffolds. Furthermore, pore geometric configurations; SZ, SS, and SO, all significantly affect on tensile moduli of scaffolds. However, only SZ and SS have statistically significant effects on compressive moduli and porosity of these scaffolds. That said, inverse linear relationship was observed between porosity and mechanical properties of 3D-printed PCL scaffolds in Pearson's correlation test. Altogether, this study illustrates that modulating MW of PCL and pore geometrical configurations of the scaffolds enabled design and fabrication of PCL scaffolds with mechanical and biomimetic properties that better mimic mechanical behaviour of human articular cartilage. Thus, the modulated PCL scaffold proposed in this study is a framework that offers great potentials for CTE applications. PMID:27328736

  10. Microseismic network design assessment based on 3D ray tracing

    NASA Astrophysics Data System (ADS)

    Näsholm, Sven Peter; Wuestefeld, Andreas; Lubrano-Lavadera, Paul; Lang, Dominik; Kaschwich, Tina; Oye, Volker

    2016-04-01

    There is increasing demand on the versatility of microseismic monitoring networks. In early projects, being able to locate any triggers was considered a success. These early successes led to a better understanding of how to extract value from microseismic results. Today operators, regulators, and service providers work closely together in order to find the optimum network design to meet various requirements. In the current study we demonstrate an integrated and streamlined network capability assessment approach. It is intended for use during the microseismic network design process prior to installation. The assessments are derived from 3D ray tracing between a grid of event points and the sensors. Three aspects are discussed: 1) Magnitude of completeness or detection limit; 2) Event location accuracy; and 3) Ground-motion hazard. The network capability parameters 1) and 2) are estimated at all hypothetic event locations and are presented in the form of maps given a seismic sensor coordinate scenario. In addition, the ray tracing traveltimes permit to estimate the point-spread-functions (PSFs) at the event grid points. PSFs are useful in assessing the resolution and focusing capability of the network for stacking-based event location and imaging methods. We estimate the performance for a hypothetical network case with 11 sensors. We consider the well-documented region around the San Andreas Fault Observatory at Depth (SAFOD) located north of Parkfield, California. The ray tracing is done through a detailed velocity model which covers a 26.2 by 21.2 km wide area around the SAFOD drill site with a resolution of 200 m both for the P-and S-wave velocities. Systematic network capability assessment for different sensor site scenarios prior to installation facilitates finding a final design which meets the survey objectives.

  11. A geometric pore-scale model for predicting the permeability of 3D flow through fibrous porous media

    NASA Astrophysics Data System (ADS)

    Woudberg, Sonia

    2012-05-01

    A geometric pore-scale model, based on rectangular geometry, is used to quantify the fluid-solid interaction in fibrous porous media in order to predict the permeability. The analytical modeling procedure is based on sound physical principles. Permeability predictions are presented for flow parallel and perpendicular to the axes of unidirectional fibres. In the latter case maximum possible staggering is introduced. A weighted average is performed to obtain the permeability prediction for 3D flow through fibrous porous media. Effects such as pore blockage at very low porosities and developing flow are incorporated into the predictive equations for the permeability to provide a model that is applicable over the entire porosity range. The resulting 3D model leads to satisfactory agreement with other three-dimensional models and data from the literature.

  12. Pore morphologies of root induced biopores from single pore to network scale investigated by XRCT

    NASA Astrophysics Data System (ADS)

    Peth, Stephan; Wittig, Marlen C.; Uteau Puschmann, Daniel; Pagenkemper, Sebastian; Haas, Christoph; Holthusen, Dörthe; Horn, Rainer

    2015-04-01

    Biopores are assumed to be an important factor for nutrient acquisition by providing biologically highly active soil-root interfaces to re-colonizing roots and controlling oxygen and water flows at the pedon scale and within the rhizosphere through the formation of branching channel networks which potentially enhance microbial turnover processes. Characteristic differences in pore morphologies are to be expected depending on the genesis of biopores which, for example, can be earthworm-induced or root-induced or subsequently modified by one of the two. Our understanding of biophysical interactions between plants and soil can be significantly improved by quantifying 3D biopore architectures across scales ranging from single biopores to pedon scale pore networks and linking pore morphologies to microscale measurements of transport processes (e.g. oxygen diffusion). While a few studies in the past have investigated biopore networks on a larger scale yet little is known on the micro-morphology of root-induces biopores and their associated rhizosphere. Also little data is available on lateral transport of oxygen through the rhizosphere which will strongly influence microbial turnover processes and consequently control the release and uptake of nutrients. This paper highlights results gathered within a research unit on nutrient acquisition from the subsoil. Here we focus on X-ray microtomography (XRCT) studies ranging from large soil columns (70 cm length and 20 cm diameter) to individual biopores and its surrounding rhizosphere. Samples were collected from sites with different preceding crops (fescue, chicory, alfalfa) and various cropping durations (1-3 years). We will present an approach for quantitative image analysis combined with micro-sensor measurements of oxygen diffusion and spatial gradients of O2 partial pressures to relate pore structure with transport functions. Implications of various biopore architectures for the accessibility of nutrient resources in

  13. 3D hierarchical porous graphene aerogel with tunable meso-pores on graphene nanosheets for high-performance energy storage.

    PubMed

    Ren, Long; Hui, K N; Hui, K S; Liu, Yundan; Qi, Xiang; Zhong, Jianxin; Du, Yi; Yang, Jianping

    2015-01-01

    New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the individual GNS were uniform and could be tuned by controlling the sizes of the Co3O4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields. PMID:26382852

  14. 3D hierarchical porous graphene aerogel with tunable meso-pores on graphene nanosheets for high-performance energy storage

    PubMed Central

    Ren, Long; Hui, K. N.; Hui, K. S.; Liu, Yundan; Qi, Xiang; Zhong, Jianxin; Du, Yi; Yang, Jianping

    2015-01-01

    New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the individual GNS were uniform and could be tuned by controlling the sizes of the Co3O4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields. PMID:26382852

  15. 3D hierarchical porous graphene aerogel with tunable meso-pores on graphene nanosheets for high-performance energy storage

    NASA Astrophysics Data System (ADS)

    Ren, Long; Hui, K. N.; Hui, K. S.; Liu, Yundan; Qi, Xiang; Zhong, Jianxin; Du, Yi; Yang, Jianping

    2015-09-01

    New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the individual GNS were uniform and could be tuned by controlling the sizes of the Co3O4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields.

  16. Nanoporous Anodic Alumina 3D FDTD Modelling for a Broad Range of Inter-pore Distances.

    PubMed

    Bertó-Roselló, Francesc; Xifré-Pérez, Elisabet; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluis F

    2016-12-01

    The capability of the finite difference time domain (FDTD) method for the numerical modelling of the optical properties of nanoporous anodic alumina (NAA) in a broad range of inter-pore distances is evaluated. FDTD permits taking into account in the same numerical framework all the structural features of NAA, such as the texturization of the interfaces or the incorporation of electrolyte anions in the aluminium oxide host. The evaluation is carried out by comparing reflectance measurements from two samples with two very different inter-pore distances with the simulation results. Results show that considering the texturization is crucial to obtain good agreement with the measurements. On the other hand, including the anionic layer in the model leads to a second-order contribution to the reflectance spectrum. PMID:27518230

  17. Estimation of water saturated permeability of soils, using 3D soil tomographic images and pore-level transport phenomena modelling

    NASA Astrophysics Data System (ADS)

    Lamorski, Krzysztof; Sławiński, Cezary; Barna, Gyöngyi

    2014-05-01

    There are some important macroscopic properties of the soil porous media such as: saturated permeability and water retention characteristics. These soil characteristics are very important as they determine soil transport processes and are commonly used as a parameters of general models of soil transport processes used extensively for scientific developments and engineering practise. These characteristics are usually measured or estimated using some statistical or phenomenological modelling, i.e. pedotransfer functions. On the physical basis, saturated soil permeability arises from physical transport processes occurring at the pore level. Current progress in modelling techniques, computational methods and X-ray micro-tomographic technology gives opportunity to use direct methods of physical modelling for pore level transport processes. Physically valid description of transport processes at micro-scale based on Navier-Stokes type modelling approach gives chance to recover macroscopic porous medium characteristics from micro-flow modelling. Water microflow transport processes occurring at the pore level are dependent on the microstructure of porous body and interactions between the fluid and the medium. In case of soils, i.e. the medium there exist relatively big pores in which water can move easily but also finer pores are present in which water transport processes are dominated by strong interactions between the medium and the fluid - full physical description of these phenomena is a challenge. Ten samples of different soils were scanned using X-ray computational microtomograph. The diameter of samples was 5 mm. The voxel resolution of CT scan was 2.5 µm. Resulting 3D soil samples images were used for reconstruction of the pore space for further modelling. 3D image threshholding was made to determine the soil grain surface. This surface was triangulated and used for computational mesh construction for the pore space. Numerical modelling of water flow through the

  18. Generation of Multi-Scale Vascular Network System within 3D Hydrogel using 3D Bio-Printing Technology.

    PubMed

    Lee, Vivian K; Lanzi, Alison M; Haygan, Ngo; Yoo, Seung-Schik; Vincent, Peter A; Dai, Guohao

    2014-09-01

    Although 3D bio-printing technology has great potential in creating complex tissues with multiple cell types and matrices, maintaining the viability of thick tissue construct for tissue growth and maturation after the printing is challenging due to lack of vascular perfusion. Perfused capillary network can be a solution for this issue; however, construction of a complete capillary network at single cell level using the existing technology is nearly impossible due to limitations in time and spatial resolution of the dispensing technology. To address the vascularization issue, we developed a 3D printing method to construct larger (lumen size of ~1mm) fluidic vascular channels and to create adjacent capillary network through a natural maturation process, thus providing a feasible solution to connect the capillary network to the large perfused vascular channels. In our model, microvascular bed was formed in between two large fluidic vessels, and then connected to the vessels by angiogenic sprouting from the large channel edge. Our bio-printing technology has a great potential in engineering vascularized thick tissues and vascular niches, as the vascular channels are simultaneously created while cells and matrices are printed around the channels in desired 3D patterns. PMID:25484989

  19. Generation of Multi-Scale Vascular Network System within 3D Hydrogel using 3D Bio-Printing Technology

    PubMed Central

    Lee, Vivian K.; Lanzi, Alison M.; Haygan, Ngo; Yoo, Seung-Schik; Vincent, Peter A.; Dai, Guohao

    2014-01-01

    Although 3D bio-printing technology has great potential in creating complex tissues with multiple cell types and matrices, maintaining the viability of thick tissue construct for tissue growth and maturation after the printing is challenging due to lack of vascular perfusion. Perfused capillary network can be a solution for this issue; however, construction of a complete capillary network at single cell level using the existing technology is nearly impossible due to limitations in time and spatial resolution of the dispensing technology. To address the vascularization issue, we developed a 3D printing method to construct larger (lumen size of ~1mm) fluidic vascular channels and to create adjacent capillary network through a natural maturation process, thus providing a feasible solution to connect the capillary network to the large perfused vascular channels. In our model, microvascular bed was formed in between two large fluidic vessels, and then connected to the vessels by angiogenic sprouting from the large channel edge. Our bio-printing technology has a great potential in engineering vascularized thick tissues and vascular niches, as the vascular channels are simultaneously created while cells and matrices are printed around the channels in desired 3D patterns. PMID:25484989

  20. Pore - to - Core Modeling of Soil Organic Matter Decomposition in 3D Soil Structures

    NASA Astrophysics Data System (ADS)

    Falconer, R. E.; Battaia, G.; Baveye, P.; Otten, W.

    2013-12-01

    There is a growing body of literature supporting the need for microbial contributions to be considered explicitly in carbon-climate models. There is also overwhelming evidence that physical protection within aggregates can play a significant role in organic matter dynamics. Yet current models of soil organic matter dynamics divide soil organic matter into conceptual pools with distinct turnover times, assuming that a combination of biochemical and physical properties control decay without explicit description. Albeit robust in their application, such models are not capable to account for changes in soil structure or microbial populations, or accurately predict the effect of wetness or priming. A spatially explicit model is presented that accounts for microbial dynamics and physical processes, permitting consideration of the heterogeneity of the physical and chemical microenvironments at scales relevant for microbes. Exemplified for fungi, we investigate how micro-scale processes manifest at the core scale with particular emphasis on evolution of CO2 and biomass distribution. The microbial model is based upon previous (Falconer et al, 2012) and includes the following processes: uptake, translocation, recycling, enzyme production, growth, spread and respiration. The model is parameterised through a combination of literature data and parameter estimation (Cazelles et al., 2012).The Carbon model comprises two pools, particulate organic matter which through enzymatic activity is converted into dissolved organic matter. The microbial and carbon dynamics occur within a 3D soil structure obtained by X-ray CT. We show that CO2 is affected not only by the amount of Carbon in the soil but also by microbial dynamics, soil structure and the spatial distribution of OM. The same amount of OM can result in substantially different respiration rates, with surprisingly more CO2 with increased clustering of OM. We can explain this from the colony dynamics, production of enzymes and

  1. Super-resolution 3D tomography of interactions and competition in the nuclear pore complex.

    PubMed

    Ma, Jiong; Goryaynov, Alexander; Yang, Weidong

    2016-03-01

    A selective barrier formed by intrinsically disordered Phe-Gly (FG) nucleoporins (Nups) allows transport receptor (TR)-facilitated translocation of signal-dependent cargos through the nuclear pore complexes (NPCs) of eukaryotic cells. However, the configuration of the FG-Nup barrier and its interactions with multiple TRs in native NPCs remain obscure. Here, we mapped the interaction sites of various TRs or FG segments within the FG-Nup barrier by using high-speed super-resolution microscopy and used these sites to reconstruct the three-dimensional tomography of the native barrier in the NPC. We found that each TR possesses a unique interaction zone within the FG-Nup barrier and that two major TRs, importin β1 and Crm1, outcompete other TRs in binding FG Nups. Moreover, TRs may alter the tomography of the FG-Nup barrier and affect one another's pathways under circumstances of heavy competition. PMID:26878241

  2. Pore network microarchitecture influences human cortical bone elasticity during growth and aging.

    PubMed

    Bala, Yohann; Lefèvre, Emmanuelle; Roux, Jean-Paul; Baron, Cécile; Lasaygues, Philippe; Pithioux, Martine; Kaftandjian, Valérie; Follet, Hélène

    2016-10-01

    Cortical porosity is a major determinant of bone strength. Haversian and Volkmann׳s canals are׳seen' as pores in 2D cross-section but fashion a dynamic network of interconnected channels in 3D, a quantifiable footprint of intracortical remodeling. Given the changes in bone remodeling across life, we hypothesized that the 3D microarchitecture of the cortical pore network influences its stiffness during growth and ageing. Cubes of cortical bone of 2 mm side-length were harvested in the distal 1/3 of the fibula in 13 growing children (mean age±SD: 13±4 yrs) and 16 adults (age: 75±13 yrs). The cubes were imaged using desktop micro-CT (8.14µm isotropic voxel size). Pores were segmented as a solid to assess pore volume fraction, number, diameter, separation, connectivity and structure model index. Elastic coefficients were derived from measurements of ultrasonic bulk compression and shear wave velocities and apparent mass density. The pore volume fraction did not significantly differ between children and adults but originates from different microarchitectural patterns. Compared to children, adults had 42% (p=0.033) higher pore number that were more connected (Connective Density: +205%, p=0.001) with a 18% (p=0.007) lower pore separation. After accounting for the contribution of pore volume fraction, axial elasticity in traction-compression mode was significantly correlated with better connectivity in growing children and with pore separation among adults. The changes in intracortical remodeling across life alter the distribution, size and connectedness of the channels from which cortical void fraction originates. These alterations in pore network microarchitecture participate in changes in compressive and shear mechanical behavior, partly in a porosity-independent manner. The assessment of pore volume fraction (i.e., porosity) provides only a limited understanding of the role of cortical void volume fraction in its mechanical properties. PMID:27389322

  3. Application of GA in optimization of pore network models generated by multi-cellular growth algorithms

    NASA Astrophysics Data System (ADS)

    Jamshidi, Saeid; Boozarjomehry, Ramin Bozorgmehry; Pishvaie, Mahmoud Reza

    2009-10-01

    In pore network modeling, the void space of a rock sample is represented at the microscopic scale by a network of pores connected by throats. Construction of a reasonable representation of the geometry and topology of the pore space will lead to a reliable prediction of the properties of porous media. Recently, the theory of multi-cellular growth (or L-systems) has been used as a flexible tool for generation of pore network models which do not require any special information such as 2D SEM or 3D pore space images. In general, the networks generated by this method are irregular pore network models which are inherently closer to the complicated nature of the porous media rather than regular lattice networks. In this approach, the construction process is controlled only by the production rules that govern the development process of the network. In this study, genetic algorithm has been used to obtain the optimum values of the uncertain parameters of these production rules to build an appropriate irregular lattice network capable of the prediction of both static and hydraulic information of the target porous medium.

  4. Topology of a percolating soil pore network

    NASA Astrophysics Data System (ADS)

    Capa-Morocho, M.; Ruiz-Ramos, M.; Hapca, S. M.; Houston, A.; Tarquis, A. M.

    2012-04-01

    A connectivity function defined by the 3D-Euler number, is a topological indicator and can be related to hydraulic properties (Vogel and Roth, 2001). This study aims to develop connectivity Euler indexes as indicators of the ability of soils for fluid percolation. The starting point was a 3D grey image acquired by X-ray computed tomography of a soil at bulk density of 1.2 mg cm-3. This image was used in the simulation of 40000 particles following a directed random walk algorithms with 7 binarization thresholds. These data consisted of 7 files containing the simulated end points of the 40000 random walks, obtained in Ruiz-Ramos et al. (2010). MATLAB software was used for computing the frequency matrix of the number of particles arriving at every end point of the random walks and their 3D representation. In a former work (Capa et al., 2011) a criteria for choosing the optimal threshold of grey value was identified: Final positions were divided in two subgroups, cg1 (positions with frequency of the number of particles received greater than the median) and cg2 (frequency lower or equal to median). Images with maximum difference between the Z coordinate of the center of gravity of both subgroups were selected as those with optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation. According to this criterion, the optimal threshold for the soil with density 1.2 mg cm-3 was 24.Thresholds above and below the optimal (23 and 25) were also considered to confirm this selection; therefore the analysis were conducted for three files (1 image with 3 grey threshold values, which have different porosity). Additionally, three random matrix simulations with the same porosity than the selected binaries images were used to test the existence of pore connectivity as a consequence of a non-random soil structure. Therefore, 6 matrix were considered (three structured and three random) for this study. Random matrix presented a normal

  5. From 2D to 3D: novel nanostructured scaffolds to investigate signalling in reconstructed neuronal networks.

    PubMed

    Bosi, Susanna; Rauti, Rossana; Laishram, Jummi; Turco, Antonio; Lonardoni, Davide; Nieus, Thierry; Prato, Maurizio; Scaini, Denis; Ballerini, Laura

    2015-01-01

    To recreate in vitro 3D neuronal circuits will ultimately increase the relevance of results from cultured to whole-brain networks and will promote enabling technologies for neuro-engineering applications. Here we fabricate novel elastomeric scaffolds able to instruct 3D growth of living primary neurons. Such systems allow investigating the emerging activity, in terms of calcium signals, of small clusters of neurons as a function of the interplay between the 2D or 3D architectures and network dynamics. We report the ability of 3D geometry to improve functional organization and synchronization in small neuronal assemblies. We propose a mathematical modelling of network dynamics that supports such a result. Entrapping carbon nanotubes in the scaffolds remarkably boosted synaptic activity, thus allowing for the first time to exploit nanomaterial/cell interfacing in 3D growth support. Our 3D system represents a simple and reliable construct, able to improve the complexity of current tissue culture models. PMID:25910072

  6. Extracting Hidden Hierarchies in 3D Distribution Networks

    NASA Astrophysics Data System (ADS)

    Modes, Carl; Magnasco, Marcelo; Katifori, Eleni

    2015-03-01

    Natural and man-made transport webs are frequently dominated by dense sets of nested cycles. The architecture of these networks - the topology and edge weights - determines how efficiently the networks perform their function. Yet, the set of tools that can characterize such a weighted cycle-rich architecture in a physically relevant, mathematically compact way is sparse. In order to fill this void, we have developed a new algorithm that rests on an abstraction of the physical `tiling' in the case of a two dimensional network to an effective tiling of an abstract surface in space that the network may be thought to sit in. Generically these abstract surfaces are richer than the plane and upon sequential removal of the weakest links by edge weight, neighboring tiles merge and a tree characterizing this merging process results. The properties of this characteristic tree can provide the physical and topological data required to describe the architecture of the network and to build physical models. This new algorithm can be used for automated phenotypic characterization of any weighted network whose structure is dominated by cycles, such as mammalian vasculature in the organs, the root networks of clonal colonies like quaking aspen, or the force networks in jammed granular matter.

  7. Extracting Hidden Hierarchies in 3D Distribution Networks

    NASA Astrophysics Data System (ADS)

    Modes, Carl D.; Magnasco, Marcelo O.; Katifori, Eleni

    2016-07-01

    Natural and man-made transport webs are frequently dominated by dense sets of nested cycles. The architecture of these networks, as defined by the topology and edge weights, determines how efficiently the networks perform their function. Yet, the set of tools that can characterize such a weighted cycle-rich architecture in a physically relevant, mathematically compact way is sparse. In order to fill this void, we have developed a new algorithm that rests on an abstraction of the physical "tiling" in the case of a two-dimensional network to an effective tiling of an abstract surface in 3-space that the network may be thought to sit in. Generically, these abstract surfaces are richer than the flat plane because there are now two families of fundamental units that may aggregate upon cutting weakest links—the plaquettes of the tiling and the longer "topological" cycles associated with the abstract surface itself. Upon sequential removal of the weakest links, as determined by a physically relevant edge weight, such as flow volume or capacity, neighboring plaquettes merge and a new tree graph characterizing this merging process results. The properties of this characteristic tree can provide the physical and topological data required to describe the architecture of the network and to build physical models. The new algorithm can be used for automated phenotypic characterization of any weighted network whose structure is dominated by cycles, such as mammalian vasculature in the organs or the force networks in jammed granular matter.

  8. Modelling multiphase dynamics during infiltration using a pore network model

    NASA Astrophysics Data System (ADS)

    Tzavaras, Jannis; Arns, Ji-Youns; Max, Koehne; Hans-Joerg, Vogel

    2013-04-01

    We present an implementation of water infiltration into a pore network model where the local water pressures is continuously updated during the transient process. The network geometry is designed to represent structured soil which is different from simple granular porous media in some respect: Pores are more elongated and less isometric and the pore size distribution is much wider and structured hierarchically. To reproduce these properties, the classical concept of pore-bodies and throats is replaced by direct measurements of pore topology and the pores below the minimal pore size of the network model are represented by a continuous network of water saturated micro pores. The latter ensures that the water phase is always continuous which affects the propagation of the water potential during infiltration. The network model is based on cylindrical pores and considers capillary and gravitational forces. The propagation of interfaces is calculated for each time step by repeatedly solving the complete set of linear equation arising from Kirchhoff's law based on mass balance at each node of the network. This is done using the public domain package ITPack. The successive overrelaxation (SOR) and the Jacobi conjugate gradient (JCG) method proved to be more robust and faster than other solvers tested for the complex topology. The model accounts for entrapped air which is assumed to be incompressible. We present first results demonstrating the impact of external forcing (i.e infiltration rate) and pore topology on the dynamics of water-gas interfaces, the volume of entrapped air and hysteresis.

  9. A free software for pore-scale modelling: solving Stokes equation for velocity fields and permeability values in 3D pore geometries

    NASA Astrophysics Data System (ADS)

    Gerke, Kirill; Vasilyev, Roman; Khirevich, Siarhei; Karsanina, Marina; Collins, Daniel; Korost, Dmitry; Mallants, Dirk

    2015-04-01

    In this contribution we introduce a novel free software which solves the Stokes equation to obtain velocity fields for low Reynolds-number flows within externally generated 3D pore geometries. Provided with velocity fields, one can calculate permeability for known pressure gradient boundary conditions via Darcy's equation. Finite-difference schemes of 2nd and 4th order of accuracy are used together with an artificial compressibility method to iteratively converge to a steady-state solution of Stokes' equation. This numerical approach is much faster and less computationally demanding than the majority of open-source or commercial softwares employing other algorithms (finite elements/volumes, lattice Boltzmann, etc.) The software consists of two parts: 1) a pre and post-processing graphical interface, and 2) a solver. The latter is efficiently parallelized to use any number of available cores (the speedup on 16 threads was up to 10-12 depending on hardware). Due to parallelization and memory optimization our software can be used to obtain solutions for 300x300x300 voxels geometries on modern desktop PCs. The software was successfully verified by testing it against lattice Boltzmann simulations and analytical solutions. To illustrate the software's applicability for numerous problems in Earth Sciences, a number of case studies have been developed: 1) identifying the representative elementary volume for permeability determination within a sandstone sample, 2) derivation of permeability/hydraulic conductivity values for rock and soil samples and comparing those with experimentally obtained values, 3) revealing the influence of the amount of fine-textured material such as clay on filtration properties of sandy soil. This work was partially supported by RSF grant 14-17-00658 (pore-scale modelling) and RFBR grants 13-04-00409-a and 13-05-01176-a.

  10. 3D microtumors in vitro supported by perfused vascular networks

    PubMed Central

    Sobrino, Agua; Phan, Duc T. T.; Datta, Rupsa; Wang, Xiaolin; Hachey, Stephanie J.; Romero-López, Mónica; Gratton, Enrico; Lee, Abraham P.; George, Steven C.; Hughes, Christopher C. W.

    2016-01-01

    There is a growing interest in developing microphysiological systems that can be used to model both normal and pathological human organs in vitro. This “organs-on-chips” approach aims to capture key structural and physiological characteristics of the target tissue. Here we describe in vitro vascularized microtumors (VMTs). This “tumor-on-a-chip” platform incorporates human tumor and stromal cells that grow in a 3D extracellular matrix and that depend for survival on nutrient delivery through living, perfused microvessels. Both colorectal and breast cancer cells grow vigorously in the platform and respond to standard-of-care therapies, showing reduced growth and/or regression. Vascular-targeting agents with different mechanisms of action can also be distinguished, and we find that drugs targeting only VEGFRs (Apatinib and Vandetanib) are not effective, whereas drugs that target VEGFRs, PDGFR and Tie2 (Linifanib and Cabozantinib) do regress the vasculature. Tumors in the VMT show strong metabolic heterogeneity when imaged using NADH Fluorescent Lifetime Imaging Microscopy and, compared to their surrounding stroma, many show a higher free/bound NADH ratio consistent with their known preference for aerobic glycolysis. The VMT platform provides a unique model for studying vascularized solid tumors in vitro. PMID:27549930

  11. 3D microtumors in vitro supported by perfused vascular networks.

    PubMed

    Sobrino, Agua; Phan, Duc T T; Datta, Rupsa; Wang, Xiaolin; Hachey, Stephanie J; Romero-López, Mónica; Gratton, Enrico; Lee, Abraham P; George, Steven C; Hughes, Christopher C W

    2016-01-01

    There is a growing interest in developing microphysiological systems that can be used to model both normal and pathological human organs in vitro. This "organs-on-chips" approach aims to capture key structural and physiological characteristics of the target tissue. Here we describe in vitro vascularized microtumors (VMTs). This "tumor-on-a-chip" platform incorporates human tumor and stromal cells that grow in a 3D extracellular matrix and that depend for survival on nutrient delivery through living, perfused microvessels. Both colorectal and breast cancer cells grow vigorously in the platform and respond to standard-of-care therapies, showing reduced growth and/or regression. Vascular-targeting agents with different mechanisms of action can also be distinguished, and we find that drugs targeting only VEGFRs (Apatinib and Vandetanib) are not effective, whereas drugs that target VEGFRs, PDGFR and Tie2 (Linifanib and Cabozantinib) do regress the vasculature. Tumors in the VMT show strong metabolic heterogeneity when imaged using NADH Fluorescent Lifetime Imaging Microscopy and, compared to their surrounding stroma, many show a higher free/bound NADH ratio consistent with their known preference for aerobic glycolysis. The VMT platform provides a unique model for studying vascularized solid tumors in vitro. PMID:27549930

  12. Electrokinetic induced solute dispersion in porous media; pore network modeling

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Schotting, Ruud; Raoof, Amir

    2013-04-01

    Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.

  13. The 3D pore structure and fluid dynamics simulation of macroporous monoliths: High permeability due to alternating channel width.

    PubMed

    Jungreuthmayer, Christian; Steppert, Petra; Sekot, Gerhard; Zankel, Armin; Reingruber, Herbert; Zanghellini, Jürgen; Jungbauer, Alois

    2015-12-18

    Polymethacrylate-based monoliths have excellent flow properties. Flow in the wide channel interconnected with narrow channels is theoretically assumed to account for favorable permeability. Monoliths were cut into 898 slices in 50nm distances and visualized by serial block face scanning electron microscopy (SBEM). A 3D structure was reconstructed and used for the calculation of flow profiles within the monolith and for calculation of pressure drop and permeability by computational fluid dynamics (CFD). The calculated and measured permeabilities showed good agreement. Small channels clearly flowed into wide and wide into small channels in a repetitive manner which supported the hypothesis describing the favorable flow properties of these materials. This alternating property is also reflected in the streamline velocity which fluctuated. These findings were corroborated by artificial monoliths which were composed of regular (interconnected) cells where narrow cells followed wide cells. In the real monolith and the artificial monoliths with interconnected flow channels similar velocity fluctuations could be observed. A two phase flow simulation showed a lateral velocity component, which may contribute to the transport of molecules to the monolith wall. Our study showed that the interconnection of small and wide pores is responsible for the excellent pressure flow properties. This study is also a guide for further design of continuous porous materials to achieve good flow properties. PMID:26615711

  14. Transport and Deposition of Nanoparticles in the Pore Network of a Reservoir Rock: Effects of Pore Surface Heterogeneity and Radial Diffusion

    NASA Astrophysics Data System (ADS)

    Pham, Ngoc; Papavassiliou, Dimitrios

    2014-03-01

    In this study, transport behavior of nanoparticles under different pore surface conditions of consolidated Berea sandstone is numerically investigated. Micro-CT scanning technique is applied to obtain 3D grayscale images of the rock sample geometry. Quantitative characterization, which is based on image analysis is done to obtain physical properties of the pore network, such as the pore size distribution and the type of each pore (dead-end, isolated, and fully connected pore). Transport of water through the rock is simulated by employing a 3D lattice Boltzmann method. The trajectories of nanopaticles moving under convection in the simulated flow field and due to molecular diffusion are monitored in the Lagrangian framework. It is assumed in the model that the particle adsorption on the pore surface, which is modeled as a pseudo-first order adsorption, is the only factor hindering particle propagation. The effect of pore surface heterogeneity to the particle breakthrough is considered, and the role of particle radial diffusion is also addressed in details. The financial support of the Advanced Energy Consortium (AEC BEG08-022) and the computational support of XSEDE (CTS090017) are acknowledged.

  15. Analyzing 3D xylem networks in Vitis vinifera using High Resolution Computed Tomography (HRCT)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent developments in High Resolution Computed Tomography (HRCT) have made it possible to visualize three dimensional (3D) xylem networks without time consuming, labor intensive physical sectioning. Here we describe a new method to visualize complex vessel networks in plants and produce a quantitat...

  16. 3D-printed fluidic networks as vasculature for engineered tissue.

    PubMed

    Kinstlinger, Ian S; Miller, Jordan S

    2016-05-24

    Fabrication of vascular networks within engineered tissue remains one of the greatest challenges facing the fields of biomaterials and tissue engineering. Historically, the structural complexity of vascular networks has limited their fabrication in tissues engineered in vitro. Recently, however, key advances have been made in constructing fluidic networks within biomaterials, suggesting a strategy for fabricating the architecture of the vasculature. These techniques build on emerging technologies within the microfluidics community as well as on 3D printing. The freeform fabrication capabilities of 3D printing are allowing investigators to fabricate fluidic networks with complex architecture inside biomaterial matrices. In this review, we examine the most exciting 3D printing-based techniques in this area. We also discuss opportunities for using these techniques to address open questions in vascular biology and biophysics, as well as for engineering therapeutic tissue substitutes in vitro. PMID:27173478

  17. Pore-controlled formation of 0D metal complexes in anionic 3D metal-organic frameworks

    SciTech Connect

    Zhang, MW; Bosch, M; Zhou, HC

    2015-01-01

    The host-guest chemistry between a series of anionic MOFs and their trapped counterions was investigated by single crystal XRD. The PCN-514 series contains crystallographically identifiable metal complexes trapped in the pores, where their formation is controlled by the size and shape of the MOF pores. A change in the structure and pore size of PCN-518 indicates that the existence of guest molecules may reciprocally affect the formation of host MOFs.

  18. Transport pathways within percolating pore space networks of granular materials

    NASA Astrophysics Data System (ADS)

    Vo, Kevin; Walker, David M.; Tordesillas, Antoinette

    2013-06-01

    Granular media can be regarded as a mixture of two components: grains and the material filling the voids or pores between the grains. Pore properties give rise to a range of applications such as modelling ground water flow, carbon capture and sequestration. The grains within a dense granular material respond to deformation (e.g., shearing or compression) by rearranging to create local zones of compression and zones of dilatation (i.e., regions of high pore space). Descriptions of the deformation are typically focused on analysis of the solid skeleton via topology of physical contact networks of grains but an alternative perspective is to consider network representations of the evolving anisotropic pore space. We demonstrate how to construct pore space networks that express the local size of voids about a grain through network edge weights. We investigate sectors of the loading history when a percolating giant component of the pore space network exists. At these states the grains are in a configuration more prone to the efficient transport of material (e.g., fluid flow, mineral/gas deposits). These pathways can be found through examination of the weighted shortest paths percolating the boundaries of the material. In particular, network weights biased towards large void space results in efficient percolating pathways traversing the shear band in the direction of principal stress within a 2D granular assembly subject to high strains.

  19. In situ 3-D mapping of pore structures and hollow grains of interplanetary dust particles with phase contrast X-ray nanotomography

    NASA Astrophysics Data System (ADS)

    Hu, Z. W.; Winarski, R. P.

    2016-06-01

    Unlocking the 3-D structure and properties of intact chondritic porous interplanetary dust particles (IDPs) in nanoscale detail is challenging, which is also complicated by atmospheric entry heating, but is important for advancing our understanding of the formation and origins of IDPs and planetary bodies as well as dust and ice agglomeration in the outer protoplanetary disk. Here, we show that indigenous pores, pristine grains, and thermal alteration products throughout intact particles can be noninvasively visualized and distinguished morphologically and microstructurally in 3-D detail down to ~10 nm by exploiting phase contrast X-ray nanotomography. We have uncovered the surprisingly intricate, submicron, and nanoscale pore structures of a ~10-μm-long porous IDP, consisting of two types of voids that are interconnected in 3-D space. One is morphologically primitive and mostly submicron-sized intergranular voids that are ubiquitous; the other is morphologically advanced and well-defined intragranular nanoholes that run through the approximate centers of ~0.3 μm or lower submicron hollow grains. The distinct hollow grains exhibit complex 3-D morphologies but in 2-D projections resemble typical organic hollow globules observed by transmission electron microscopy. The particle, with its outer region characterized by rough vesicular structures due to thermal alteration, has turned out to be an inherently fragile and intricately submicron- and nanoporous aggregate of the sub-μm grains or grain clumps that are delicately bound together frequently with little grain-to-grain contact in 3-D space.

  20. In situ 3-D mapping of pore structures and hollow grains of interplanetary dust particles with phase contrast X-ray nanotomography

    NASA Astrophysics Data System (ADS)

    Hu, Z. W.; Winarski, R. P.

    2016-09-01

    Unlocking the 3-D structure and properties of intact chondritic porous interplanetary dust particles (IDPs) in nanoscale detail is challenging, which is also complicated by atmospheric entry heating, but is important for advancing our understanding of the formation and origins of IDPs and planetary bodies as well as dust and ice agglomeration in the outer protoplanetary disk. Here, we show that indigenous pores, pristine grains, and thermal alteration products throughout intact particles can be noninvasively visualized and distinguished morphologically and microstructurally in 3-D detail down to ~10 nm by exploiting phase contrast X-ray nanotomography. We have uncovered the surprisingly intricate, submicron, and nanoscale pore structures of a ~10-μm-long porous IDP, consisting of two types of voids that are interconnected in 3-D space. One is morphologically primitive and mostly submicron-sized intergranular voids that are ubiquitous; the other is morphologically advanced and well-defined intragranular nanoholes that run through the approximate centers of ~0.3 μm or lower submicron hollow grains. The distinct hollow grains exhibit complex 3-D morphologies but in 2-D projections resemble typical organic hollow globules observed by transmission electron microscopy. The particle, with its outer region characterized by rough vesicular structures due to thermal alteration, has turned out to be an inherently fragile and intricately submicron- and nanoporous aggregate of the sub-μm grains or grain clumps that are delicately bound together frequently with little grain-to-grain contact in 3-D space.

  1. Ex vivo 3D osteocyte network construction with primary murine bone cells

    PubMed Central

    Sun, Qiaoling; Gu, Yexin; Zhang, Wenting; Dziopa, Leah; Zilberberg, Jenny; Lee, Woo

    2015-01-01

    Osteocytes reside as three-dimensionally (3D) networked cells in the lacunocanalicular structure of bones and regulate bone and mineral homeostasis. Despite of their important regulatory roles, in vitro studies of osteocytes have been challenging because: (1) current cell lines do not sufficiently represent the phenotypic features of mature osteocytes and (2) primary cells rapidly differentiate to osteoblasts upon isolation. In this study, we used a 3D perfusion culture approach to: (1) construct the 3D cellular network of primary murine osteocytes by biomimetic assembly with microbeads and (2) reproduce ex vivo the phenotype of primary murine osteocytes, for the first time to our best knowledge. In order to enable 3D construction with a sufficient number of viable cells, we used a proliferated osteoblastic population of healthy cells outgrown from digested bone chips. The diameter of microbeads was controlled to: (1) distribute and entrap cells within the interstitial spaces between the microbeads and (2) maintain average cell-to-cell distance to be about 19 µm. The entrapped cells formed a 3D cellular network by extending and connecting their processes through openings between the microbeads. Also, with increasing culture time, the entrapped cells exhibited the characteristic gene expressions (SOST and FGF23) and nonproliferative behavior of mature osteocytes. In contrast, 2D-cultured cells continued their osteoblastic differentiation and proliferation. This 3D biomimetic approach is expected to provide a new means of: (1) studying flow-induced shear stress on the mechanotransduction function of primary osteocytes, (2) studying physiological functions of 3D-networked osteocytes with in vitro convenience, and (3) developing clinically relevant human bone disease models. PMID:26421212

  2. 3D Slicer as an Image Computing Platform for the Quantitative Imaging Network

    PubMed Central

    Fedorov, Andriy; Beichel, Reinhard; Kalpathy-Cramer, Jayashree; Finet, Julien; Fillion-Robin, Jean-Christophe; Pujol, Sonia; Bauer, Christian; Jennings, Dominique; Fennessy, Fiona; Sonka, Milan; Buatti, John; Aylward, Stephen; Miller, James V.; Pieper, Steve; Kikinis, Ron

    2012-01-01

    Quantitative analysis has tremendous but mostly unrealized potential in healthcare to support objective and accurate interpretation of the clinical imaging. In 2008, the National Cancer Institute began building the Quantitative Imaging Network (QIN) initiative with the goal of advancing quantitative imaging in the context of personalized therapy and evaluation of treatment response. Computerized analysis is an important component contributing to reproducibility and efficiency of the quantitative imaging techniques. The success of quantitative imaging is contingent on robust analysis methods and software tools to bring these methods from bench to bedside. 3D Slicer is a free open source software application for medical image computing. As a clinical research tool, 3D Slicer is similar to a radiology workstation that supports versatile visualizations but also provides advanced functionality such as automated segmentation and registration for a variety of application domains. Unlike a typical radiology workstation, 3D Slicer is free and is not tied to specific hardware. As a programming platform, 3D Slicer facilitates translation and evaluation of the new quantitative methods by allowing the biomedical researcher to focus on the implementation of the algorithm, and providing abstractions for the common tasks of data communication, visualization and user interface development. Compared to other tools that provide aspects of this functionality, 3D Slicer is fully open source and can be readily extended and redistributed. In addition, 3D Slicer is designed to facilitate the development of new functionality in the form of 3D Slicer extensions. In this paper, we present an overview of 3D Slicer as a platform for prototyping, development and evaluation of image analysis tools for clinical research applications. To illustrate the utility of the platform in the scope of QIN, we discuss several use cases of 3D Slicer by the existing QIN teams, and we elaborate on the future

  3. 3D Slicer as an image computing platform for the Quantitative Imaging Network.

    PubMed

    Fedorov, Andriy; Beichel, Reinhard; Kalpathy-Cramer, Jayashree; Finet, Julien; Fillion-Robin, Jean-Christophe; Pujol, Sonia; Bauer, Christian; Jennings, Dominique; Fennessy, Fiona; Sonka, Milan; Buatti, John; Aylward, Stephen; Miller, James V; Pieper, Steve; Kikinis, Ron

    2012-11-01

    Quantitative analysis has tremendous but mostly unrealized potential in healthcare to support objective and accurate interpretation of the clinical imaging. In 2008, the National Cancer Institute began building the Quantitative Imaging Network (QIN) initiative with the goal of advancing quantitative imaging in the context of personalized therapy and evaluation of treatment response. Computerized analysis is an important component contributing to reproducibility and efficiency of the quantitative imaging techniques. The success of quantitative imaging is contingent on robust analysis methods and software tools to bring these methods from bench to bedside. 3D Slicer is a free open-source software application for medical image computing. As a clinical research tool, 3D Slicer is similar to a radiology workstation that supports versatile visualizations but also provides advanced functionality such as automated segmentation and registration for a variety of application domains. Unlike a typical radiology workstation, 3D Slicer is free and is not tied to specific hardware. As a programming platform, 3D Slicer facilitates translation and evaluation of the new quantitative methods by allowing the biomedical researcher to focus on the implementation of the algorithm and providing abstractions for the common tasks of data communication, visualization and user interface development. Compared to other tools that provide aspects of this functionality, 3D Slicer is fully open source and can be readily extended and redistributed. In addition, 3D Slicer is designed to facilitate the development of new functionality in the form of 3D Slicer extensions. In this paper, we present an overview of 3D Slicer as a platform for prototyping, development and evaluation of image analysis tools for clinical research applications. To illustrate the utility of the platform in the scope of QIN, we discuss several use cases of 3D Slicer by the existing QIN teams, and we elaborate on the future

  4. Modeling and simulating the adaptive electrical properties of stochastic polymeric 3D networks

    NASA Astrophysics Data System (ADS)

    Sigala, R.; Smerieri, A.; Schüz, A.; Camorani, P.; Erokhin, V.

    2013-10-01

    Memristors are passive two-terminal circuit elements that combine resistance and memory. Although in theory memristors are a very promising approach to fabricate hardware with adaptive properties, there are only very few implementations able to show their basic properties. We recently developed stochastic polymeric matrices with a functionality that evidences the formation of self-assembled three-dimensional (3D) networks of memristors. We demonstrated that those networks show the typical hysteretic behavior observed in the ‘one input-one output’ memristive configuration. Interestingly, using different protocols to electrically stimulate the networks, we also observed that their adaptive properties are similar to those present in the nervous system. Here, we model and simulate the electrical properties of these self-assembled polymeric networks of memristors, the topology of which is defined stochastically. First, we show that the model recreates the hysteretic behavior observed in the real experiments. Second, we demonstrate that the networks modeled indeed have a 3D instead of a planar functionality. Finally, we show that the adaptive properties of the networks depend on their connectivity pattern. Our model was able to replicate fundamental qualitative behavior of the real organic 3D memristor networks; yet, through the simulations, we also explored other interesting properties, such as the relation between connectivity patterns and adaptive properties. Our model and simulations represent an interesting tool to understand the very complex behavior of self-assembled memristor networks, which can finally help to predict and formulate hypotheses for future experiments.

  5. Exploring thermal spray gray alumina coating pore network architecture by combining stereological protocols and impedance electrochemical spectroscopy

    NASA Astrophysics Data System (ADS)

    Antou, G.; Montavon, G.; Hlawka, F.; Cornet, A.; Coddet, C.

    2006-12-01

    Complex multiscale pore network architecture characterized by multimodal pore size distribution and connectivity develops during the manufacture of ceramic thermal spray coatings from intra- and interlamellar cracks generated when each lamella spreads and solidifies to globular pores resulting from lamella stacking defects. This network significantly affects the coating properties and their in-service behaviors. De Hoff stereological analysis permits quantification of the three-dimensional (3D) distribution of spheroids (i.e., pores) from the determination of their two-dimensional (2D) distribution estimated by image analysis when analyzing the coating structure from a polished plane. Electrochemical impedance spectroscopy electrochemically examines a material surface by frequency variable current and potential and analyzes the complex impedance. When a coating covers the material surface, the electrolyte percolates through the more or less connected pore network to locally passivate the substrate. The resistive and capacitive characteristics of the equivalent electrical circuit will depend upon the connected pore network architecture. Both protocols were implemented to quantify thermal spray coating structures. Al2O3-13TiO2 coatings were atmospherically plasma sprayed using several sets of power parameters, are current intensity, plasma gas total flow rate, and plasma gas composition in order to determine their effects on pore network architecture. Particle characteristics upon impact, especially their related dimensionless numbers, such as Reynolds, Weber, and Sommerfeld criteria, were also determined. Analyses permitted identification of (a) the major effects of power parameters upon pore architecture and (b) the related formation mechanisms.

  6. Development of 3-D fracture network visualization software based on graphical user interface

    NASA Astrophysics Data System (ADS)

    Young-Hwan, Noh; Jeong-Gi, Um; Yosoon, Choi; Myong-Ho, Park; Jaeyoung, Choi

    2013-04-01

    A sound understanding of the structural characteristics of fractured rock masses is important in designing and maintaining earth structures because their strength, deformability, and hydraulic behavior depend mainly on the characteristics of discontinuity network structures. Despite considerable progress in understanding the structural characteristics of rock masses, the complexity of discontinuity patterns has prevented satisfactory analysis based on a 3-D rock mass visualization model. This research presents the results of studies performed to develop rock mass visualization in 3-D to analysis the mechanical and hydraulic behavior of fractured rock masses. General and particular solutions of non-linear equations of disk-shaped fractures have been derived to calculated lines of intersection and equivalent pipes. Also, program modules of DISK3D, FNTWK3D, BOUNDARY and BDM(borehole data management) have been developed to perform the visualization of fracture network and corresponding equivalent pipes for DFN based fluid flow model. The developed software for the 3-D fractured rock mass visualization model based on MS visual studio can be used to characterize rock mass geometry and network systems effectively. The results obtained in this study will be refined and then combined for use as a tool for assessing geomechanical problems related to strength, deformability and hydraulic behaviors of the fractured rock masses. Acknowledgements. This work was supported by the 2011 Energy Efficiency and Resources Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant.

  7. Assessment of the 3 D Pore Structure and Individual Components of Preshaped Catalyst Bodies by X-Ray Imaging

    PubMed Central

    da Silva, Julio C; Mader, Kevin; Holler, Mirko; Haberthür, David; Diaz, Ana; Guizar-Sicairos, Manuel; Cheng, Wu-Cheng; Shu, Yuying; Raabe, Jörg; Menzel, Andreas; van Bokhoven, Jeroen A

    2015-01-01

    Porosity in catalyst particles is essential because it enables reactants to reach the active sites and it enables products to leave the catalyst. The engineering of composite-particle catalysts through the tuning of pore-size distribution and connectivity is hampered by the inability to visualize structure and porosity at critical-length scales. Herein, it is shown that the combination of phase-contrast X-ray microtomography and high-resolution ptychographic X-ray tomography allows the visualization and characterization of the interparticle pores at micro- and nanometer-length scales. Furthermore, individual components in preshaped catalyst bodies used in fluid catalytic cracking, one of the most used catalysts, could be visualized and identified. The distribution of pore sizes, as well as enclosed pores, which cannot be probed by traditional methods, such as nitrogen physisorption and isotherm analysis, were determined. PMID:26191088

  8. Modeling blood flow circulation in intracranial arterial networks: a comparative 3D/1D simulation study.

    PubMed

    Grinberg, L; Cheever, E; Anor, T; Madsen, J R; Karniadakis, G E

    2011-01-01

    We compare results from numerical simulations of pulsatile blood flow in two patient-specific intracranial arterial networks using one-dimensional (1D) and three-dimensional (3D) models. Specifically, we focus on the pressure and flowrate distribution at different segments of the network computed by the two models. Results obtained with 1D and 3D models with rigid walls show good agreement in massflow distribution at tens of arterial junctions and also in pressure drop along the arteries. The 3D simulations with the rigid walls predict higher amplitude of the flowrate and pressure temporal oscillations than the 1D simulations with compliant walls at various segments even for small time-variations in the arterial cross-sectional areas. Sensitivity of the flow and pressure with respect to variation in the elasticity parameters is investigated with the 1D model. PMID:20661645

  9. A fast and robust new pore-network extraction method based on hybrid median axis and maximal inscribed ball techniques

    NASA Astrophysics Data System (ADS)

    Timofey, Sizonenko; Karsanina, Marina; Byuk, Irina; Gerke, Kirill

    2016-04-01

    To characterize pore structure relevant to single and multi-phase flow modelling it is of special interest to extract topology of the pore space. This is usually achieved using so-called pore-network models. Such models are useful not only to characterize pore space and pore size distributions, but also provide means to simulate flow and transport with very limited computational resources compared to other pore-scale modelling techniques. The main drawback of the pore-network approach is that they have first to simplify the pore space geometry. This crucial step is both time consuming and prone to numerous errors. Two most popular methods based on median axis or inscribed maximal balls have their own strong sides and disadvantages. To address aforementioned problems related to pore-network extraction here we propose a novel method utilizing the advantages of both popular approaches. Combining two algorithms resulted in much faster and robust extraction methodology. Moreover, we have found that accurate topology representation requires extension of the conventional pore-body and pore-throat classification. We test our new methodology using pore structures with "analytical solutions" such as different sphere packs. In addition, we rigorously compare it against inscribed maximal balls methodology's results using numerous 3D images of sandstone and carbonate rocks, soils and some other porous materials. Another verification includes permeability calculations which are also compared both against lab data and voxel based pore-scale modelling simulations. This work was partially supported by RFBR grant 15-34-20989 (X-ray tomography and image fusion) and RSF grant 14-17-00658 (image segmentation and pore-scale modelling).

  10. Efficient routing in network-on-chip for 3D topologies

    NASA Astrophysics Data System (ADS)

    Silva Junior, Luneque; Nedjah, Nadia; De Macedo Mourelle, Luiza

    2015-10-01

    With the increasing of the integration capability intra-chip, nowadays numerous integrated systems explore a set of processing elements, such as in multicore processors. An efficient interconnection of those elements can be obtained via the use of Network on chip (NoC). This approach is similar to the traditional computer networks where, not restricted to multiprocessors, it is possible to interconnect several dedicated devices. Like other networks, NoCs can be arranged in different topologies, such as ring, mesh and torus. It has shared links that can be used in the transmission of packets of different nodes. Thus, the network congestion is an issue and must be treated to reduce delays. Algorithms based on ant colony optimisation have proven to be effective in static routing in systems designed to perform a fixed set of tasks, or where the communication pattern is known. This article introduces 3D ant colony routing (3D-ACR) and applies it as routing policy of NoCs having three different 3D topologies: mesh, torus and hypercube. Experimental results show that 3D ant colony routing performs consistently better compared with the previously proposed routing strategies.

  11. Development of a new software for analyzing 3-D fracture network

    NASA Astrophysics Data System (ADS)

    Um, Jeong-Gi; Noh, Young-Hwan; Choi, Yosoon

    2014-05-01

    A new software is presented to analyze fracture network in 3-D. Recently, we completed the software package based on information given in EGU2013. The software consists of several modules that play roles in management of borehole data, stochastic modelling of fracture network, construction of analysis domain, visualization of fracture geometry in 3-D, calculation of equivalent pipes and production of cross-section diagrams. Intel Parallel Studio XE 2013, Visual Studio.NET 2010 and the open source VTK library were utilized as development tools to efficiently implement the modules and the graphical user interface of the software. A case study was performed to analyze 3-D fracture network system at the Upper Devonian Grosmont Formation in Alberta, Canada. The results have suggested that the developed software is effective in modelling and visualizing 3-D fracture network system, and can provide useful information to tackle the geomechanical problems related to strength, deformability and hydraulic behaviours of the fractured rock masses. This presentation describes the concept and details of the development and implementation of the software.

  12. Next generation 3-D OFDM based optical access networks using FEC under various system impairments

    NASA Astrophysics Data System (ADS)

    Kumar, Pravindra; Srivastava, Anand

    2013-12-01

    Passive optical network based on orthogonal frequency division multiplexing (OFDM-PON) exhibits excellent performance in optical access networks due to its greater resistance to fiber dispersion, high spectral efficiency and exibility on both multiple services and dynamic bandwidth allocation. The major elements of conventional OFDM communication system are two-dimensional (2-D) signal mapper and one-dimensional (1-D) inverse fast fourier transform (IFFT). Three dimensional (3-D) OFDM use the concept of 3-D signal mapper and 2-D IFFT. With 3-D OFDM, minimum Euclidean distance (MED) is increased which results in BER performance improvement. As bit error rate (BER) depends on minimum Euclidean distance (MED) which is 15.46 % more in case of 3-D OFDM as compared to 2-D OFDM. Forward error correction (FEC) coding is a technique where redundancy is added to original bit sequence to increase the reliability of communication system. In this paper, we propose and analytically analyze a new PON architecture based on 3-D OFDM with convolutional coding and Viterbi decoding and is compared with conventional 2-D OFDM under various system impairments for coherent optical orthogonal frequency division multiplexing (CO-OFDM) without using any optical dispersion compensation. Analytical result show that at BER of 10-9, there is 2.7 dB, 3.8 dB and 9.3 dB signal-to-noise ratio (SNR) gain with 3-D OFDM, 3-D OFDM combined with convolutional coding and Viterbi hard decision decoding (CC-HDD) and 3-D OFDM combined with convolutional coding and Viterbi soft decision decoding (CC-SDD) respectively as compared to 2-D OFDM-PON. At BER of 10-9, 3-D OFDM-PON with CC-HDD gives 2.8 dB improvement in optical budget for both upstream and downstream path and gives 5.7 dB improvement in optical budget using 3-D OFDM-PON combined with CC-SDD as compared to conventional OFDM-PON system.

  13. 3D Chemical Similarity Networks for Structure-Based Target Prediction and Scaffold Hopping.

    PubMed

    Lo, Yu-Chen; Senese, Silvia; Damoiseaux, Robert; Torres, Jorge Z

    2016-08-19

    Target identification remains a major challenge for modern drug discovery programs aimed at understanding the molecular mechanisms of drugs. Computational target prediction approaches like 2D chemical similarity searches have been widely used but are limited to structures sharing high chemical similarity. Here, we present a new computational approach called chemical similarity network analysis pull-down 3D (CSNAP3D) that combines 3D chemical similarity metrics and network algorithms for structure-based drug target profiling, ligand deorphanization, and automated identification of scaffold hopping compounds. In conjunction with 2D chemical similarity fingerprints, CSNAP3D achieved a >95% success rate in correctly predicting the drug targets of 206 known drugs. Significant improvement in target prediction was observed for HIV reverse transcriptase (HIVRT) compounds, which consist of diverse scaffold hopping compounds targeting the nucleotidyltransferase binding site. CSNAP3D was further applied to a set of antimitotic compounds identified in a cell-based chemical screen and identified novel small molecules that share a pharmacophore with Taxol and display a Taxol-like mechanism of action, which were validated experimentally using in vitro microtubule polymerization assays and cell-based assays. PMID:27285961

  14. Minimal camera networks for 3D image based modeling of cultural heritage objects.

    PubMed

    Alsadik, Bashar; Gerke, Markus; Vosselman, George; Daham, Afrah; Jasim, Luma

    2014-01-01

    3D modeling of cultural heritage objects like artifacts, statues and buildings is nowadays an important tool for virtual museums, preservation and restoration. In this paper, we introduce a method to automatically design a minimal imaging network for the 3D modeling of cultural heritage objects. This becomes important for reducing the image capture time and processing when documenting large and complex sites. Moreover, such a minimal camera network design is desirable for imaging non-digitally documented artifacts in museums and other archeological sites to avoid disturbing the visitors for a long time and/or moving delicate precious objects to complete the documentation task. The developed method is tested on the Iraqi famous statue "Lamassu". Lamassu is a human-headed winged bull of over 4.25 m in height from the era of Ashurnasirpal II (883-859 BC). Close-range photogrammetry is used for the 3D modeling task where a dense ordered imaging network of 45 high resolution images were captured around Lamassu with an object sample distance of 1 mm. These images constitute a dense network and the aim of our study was to apply our method to reduce the number of images for the 3D modeling and at the same time preserve pre-defined point accuracy. Temporary control points were fixed evenly on the body of Lamassu and measured by using a total station for the external validation and scaling purpose. Two network filtering methods are implemented and three different software packages are used to investigate the efficiency of the image orientation and modeling of the statue in the filtered (reduced) image networks. Internal and external validation results prove that minimal image networks can provide highly accurate records and efficiency in terms of visualization, completeness, processing time (>60% reduction) and the final accuracy of 1 mm. PMID:24670718

  15. Minimal Camera Networks for 3D Image Based Modeling of Cultural Heritage Objects

    PubMed Central

    Alsadik, Bashar; Gerke, Markus; Vosselman, George; Daham, Afrah; Jasim, Luma

    2014-01-01

    3D modeling of cultural heritage objects like artifacts, statues and buildings is nowadays an important tool for virtual museums, preservation and restoration. In this paper, we introduce a method to automatically design a minimal imaging network for the 3D modeling of cultural heritage objects. This becomes important for reducing the image capture time and processing when documenting large and complex sites. Moreover, such a minimal camera network design is desirable for imaging non-digitally documented artifacts in museums and other archeological sites to avoid disturbing the visitors for a long time and/or moving delicate precious objects to complete the documentation task. The developed method is tested on the Iraqi famous statue “Lamassu”. Lamassu is a human-headed winged bull of over 4.25 m in height from the era of Ashurnasirpal II (883–859 BC). Close-range photogrammetry is used for the 3D modeling task where a dense ordered imaging network of 45 high resolution images were captured around Lamassu with an object sample distance of 1 mm. These images constitute a dense network and the aim of our study was to apply our method to reduce the number of images for the 3D modeling and at the same time preserve pre-defined point accuracy. Temporary control points were fixed evenly on the body of Lamassu and measured by using a total station for the external validation and scaling purpose. Two network filtering methods are implemented and three different software packages are used to investigate the efficiency of the image orientation and modeling of the statue in the filtered (reduced) image networks. Internal and external validation results prove that minimal image networks can provide highly accurate records and efficiency in terms of visualization, completeness, processing time (>60% reduction) and the final accuracy of 1 mm. PMID:24670718

  16. Structure of residual oil as a function of wettability using pore-network modelling

    NASA Astrophysics Data System (ADS)

    Ryazanov, A. V.; Sorbie, K. S.; van Dijke, M. I. J.

    2014-01-01

    In the water flooding of mixed-wet porous media, oil may drain down to relatively low residual oil saturations (Sor). Various studies have indicated that such low saturations can only be reached when oil layers in pore corners are included in the pore-scale modelling. These processes within a macroscopic porous medium can be modelled at the pore-scale by incorporating the fundamental physics of capillary dominated displacement within idealised pore network models. Recently, the authors have developed thermodynamic criteria for oil layer existence in pores with non-uniform wettability which takes as input geometrically and topologically representative networks, to calculate realistic Sor values for mixed-wet and oil-wet sandstones [16, 21]. This previous work is developed in this paper to include (i) the visualisation of the 3D structure of this residual oil, and (ii) a statistical analysis of this "residual/remaining" oil. Both the visualisation and the statistical analysis are done under a wide range of wettability conditions, which is reported for the first time in this paper.

  17. GIS Data Based Automatic High-Fidelity 3D Road Network Modeling

    NASA Technical Reports Server (NTRS)

    Wang, Jie; Shen, Yuzhong

    2011-01-01

    3D road models are widely used in many computer applications such as racing games and driving simulations_ However, almost all high-fidelity 3D road models were generated manually by professional artists at the expense of intensive labor. There are very few existing methods for automatically generating 3D high-fidelity road networks, especially those existing in the real world. This paper presents a novel approach thai can automatically produce 3D high-fidelity road network models from real 2D road GIS data that mainly contain road. centerline in formation. The proposed method first builds parametric representations of the road centerlines through segmentation and fitting . A basic set of civil engineering rules (e.g., cross slope, superelevation, grade) for road design are then selected in order to generate realistic road surfaces in compliance with these rules. While the proposed method applies to any types of roads, this paper mainly addresses automatic generation of complex traffic interchanges and intersections which are the most sophisticated elements in the road networks

  18. Interplay between the magnetic and magneto-transport properties of 3D interconnected nanowire networks

    NASA Astrophysics Data System (ADS)

    da Câmara Santa Clara Gomes, Tristan; De La Torre Medina, Joaquín; Velázquez-Galván, Yenni G.; Martínez-Huerta, Juan Manuel; Encinas, Armando; Piraux, Luc

    2016-07-01

    We have explored the interplay between the magnetic and magneto-transport properties of 3D interconnected nanowire networks made of various magnetic metals by electrodeposition into nanoporous membranes with crossed channels and controlled topology. The close relationship between their magnetic and structural properties has a direct impact on their magneto-transport behavior. In order to accurately and reliably describe the effective magnetic anisotropy and anisotropic magnetoresistance, an analytical model inherent to the topology of 3D nanowire networks is proposed and validated. The feasibility to obtain magneto-transport responses in nanowire network films based on interconnected nanowires makes them very attractive for the development of mechanically stable superstructures that are suitable for potential technological applications.

  19. Reliable and Fault-Tolerant Software-Defined Network Operations Scheme for Remote 3D Printing

    NASA Astrophysics Data System (ADS)

    Kim, Dongkyun; Gil, Joon-Min

    2015-03-01

    The recent wide expansion of applicable three-dimensional (3D) printing and software-defined networking (SDN) technologies has led to a great deal of attention being focused on efficient remote control of manufacturing processes. SDN is a renowned paradigm for network softwarization, which has helped facilitate remote manufacturing in association with high network performance, since SDN is designed to control network paths and traffic flows, guaranteeing improved quality of services by obtaining network requests from end-applications on demand through the separated SDN controller or control plane. However, current SDN approaches are generally focused on the controls and automation of the networks, which indicates that there is a lack of management plane development designed for a reliable and fault-tolerant SDN environment. Therefore, in addition to the inherent advantage of SDN, this paper proposes a new software-defined network operations center (SD-NOC) architecture to strengthen the reliability and fault-tolerance of SDN in terms of network operations and management in particular. The cooperation and orchestration between SDN and SD-NOC are also introduced for the SDN failover processes based on four principal SDN breakdown scenarios derived from the failures of the controller, SDN nodes, and connected links. The abovementioned SDN troubles significantly reduce the network reachability to remote devices (e.g., 3D printers, super high-definition cameras, etc.) and the reliability of relevant control processes. Our performance consideration and analysis results show that the proposed scheme can shrink operations and management overheads of SDN, which leads to the enhancement of responsiveness and reliability of SDN for remote 3D printing and control processes.

  20. Prediction of empirical properties using direct pore-scale simulation of straining through 3D microtomography images of porous media

    NASA Astrophysics Data System (ADS)

    Mirabolghasemi, Maryam; Prodanović, Maša; DiCarlo, David; Ji, Hongyu

    2015-10-01

    Understanding the mechanisms of filtration through porous media is relevant in many engineering applications ranging from waste water treatment and aquifer contamination in environmental engineering to estimating the permeability reduction in near wellbore region during drilling or water re-injection in petroleum engineering. In this paper we present a pore-scale approach that models straining through the pore structures extracted from X-ray tomographic images of rock and grain pack samples from the first principles, enabling the examination of current macroscopic models. While continuum models are widely used for fast prediction of the retention profiles and permeability of the host porous medium, they require a number of phenomenological parameters which are derived from matching experimental results. One of these parameters is the rate of entrapment, which is the sink term in the advection-diffusion equation. Here we find the constitutive relationship for the rate of entrapment as a product of the filtration coefficient, velocity, and concentration and validate it by comparing with core flood experiments. Results show that the pore-scale simulation gives close approximations of filtration coefficient when pore bridging and straining are the main particle capture mechanisms.

  1. Reactive transport in porous media: pore-network model approach compared to pore-scale model.

    PubMed

    Varloteaux, Clément; Vu, Minh Tan; Békri, Samir; Adler, Pierre M

    2013-02-01

    Accurate determination of three macroscopic parameters governing reactive transport in porous media, namely, the apparent solute velocity, the dispersion, and the apparent reaction rate, is of key importance for predicting solute migration through reservoir aquifers. Two methods are proposed to calculate these parameters as functions of the Péclet and the Péclet-Dahmköhler numbers. In the first method called the pore-scale model (PSM), the porous medium is discretized by the level set method; the Stokes and convection-diffusion equations with reaction at the wall are solved by a finite-difference scheme. In the second method, called the pore-network model (PNM), the void space of the porous medium is represented by an idealized geometry of pore bodies joined by pore throats; the flow field is computed by solving Kirchhoff's laws and transport calculations are performed in the asymptotic regime where the solute concentration undergoes an exponential evolution with time. Two synthetic geometries of porous media are addressed by using both numerical codes. The first geometry is constructed in order to validate the hypotheses implemented in PNM. PSM is also used for a better understanding of the various reaction patterns observed in the asymptotic regime. Despite the PNM approximations, a very good agreement between the models is obtained, which shows that PNM is an accurate description of reactive transport. PNM, which can address much larger pore volumes than PSM, is used to evaluate the influence of the concentration distribution on macroscopic properties of a large irregular network reconstructed from microtomography images. The role of the dimensionless numbers and of the location and size of the largest pore bodies is highlighted. PMID:23496613

  2. Network representation of pore scale imagery for percolation models

    NASA Astrophysics Data System (ADS)

    Klise, K. A.; McKenna, S. A.; Read, E.; Karpyn, Z. T.; Celauro, J.

    2012-12-01

    Multiphase flow under capillary dominated flow regimes is driven by an intricate relationship between pore geometry, material and fluid properties. In this research, high-resolution micro-computed tomography (CT) imaging experiments are used to investigate structural and surface properties of bead packs, and how they influence percolation pathways. Coreflood experiments use a mix of hydrophilic and hydrophobic beads to track the influence of variable contact angle on capillary flow. While high-resolution CT images can render micron scale representation of the pore space, data must be upscaled to capture pore and pore throat geometry for use in percolation models. In this analysis, the pore space is upscaled into a network representation based on properties of the medial axis. Finding the medial axis using micron scale images is computationally expensive. Here, we compare the efficiency and accuracy of medial axes using erosion-based and watershed algorithms. The resulting network representation is defined as a ball-and-stick model which represents pores and pore throats. The ball-and-stick model can be further reduced by eliminating sections of the network that fall below a capillary pressure threshold. In a system of mixed hydrophilic and hydrophobic beads, capillary pressure can change significantly throughout the network based on the interaction between surface and fluid properties. The upscaled network representations are used in percolation models to estimate transport pathway. Current results use a basic percolation model that sequentially fills neighboring pores with the highest potential. Future work will expand the percolation model to include additional mechanics, such as trapping, vacating pores, and viscous fingering. Results from the coreflood experiments will be used to validate upscaling techniques and percolation models. Preliminary results show that the relative strength of water-wet and oil-wet surfaces has a significant impact on percolation

  3. Neuronal-glial populations form functional networks in a biocompatible 3D scaffold.

    PubMed

    Smith, Imogen; Haag, Marcus; Ugbode, Christopher; Tams, Daniel; Rattray, Marcus; Przyborski, Stefan; Bithell, Angela; Whalley, Benjamin J

    2015-11-16

    Monolayers of neurons and glia have been employed for decades as tools for the study of cellular physiology and as the basis for a variety of standard toxicological assays. A variety of three dimensional (3D) culture techniques have been developed with the aim to produce cultures that recapitulate desirable features of intact. In this study, we investigated the effect of preparing primary mouse mixed neuron and glial cultures in the inert 3D scaffold, Alvetex. Using planar multielectrode arrays, we compared the spontaneous bioelectrical activity exhibited by neuroglial networks grown in the scaffold with that seen in the same cells prepared as conventional monolayer cultures. Two dimensional (monolayer; 2D) cultures exhibited a significantly higher spike firing rate than that seen in 3D cultures although no difference was seen in total signal power (<50Hz) while pharmacological responsiveness of each culture type to antagonism of GABAAR, NMDAR and AMPAR was highly comparable. Interestingly, correlation of burst events, spike firing and total signal power (<50Hz) revealed that local field potential events were associated with action potential driven bursts as was the case for 2D cultures. Moreover, glial morphology was more physiologically normal in 3D cultures. These results show that 3D culture in inert scaffolds represents a more physiologically normal preparation which has advantages for physiological, pharmacological, toxicological and drug development studies, particularly given the extensive use of such preparations in high throughput and high content systems. PMID:26493605

  4. 3D self-consistent percolative model for networks of randomly aligned carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Colasanti, S.; Deep Bhatt, V.; Abdellah, A.; Lugli, P.

    2015-10-01

    A numerical percolative model for simulations of random networks of carbon nanotubes is presented. This algorithm takes into account the real 3D nature of these networks, allowing for a better understanding of their electrical properties. The nanotubes are modeled as non-rigid bendable cylinders with geometrical properties derived according to some statistical distributions inferred from the experiments. For the transport mechanisms we refer to the theory of one-dimensional ballistic channels which is based on the computation of the density of states. The behavior of the entire network is then simulated by coupling a SPICE program with an iterative algorithm that calculates self-consistently the electrostatic potential and the current flow in each node of the network. We performed several simulations on the resistivity of networks with different thicknesses and over different simulation domains. Our results confirm the percolative nature of the electrical transport, which are more pronounced in films close to their percolation threshold.

  5. Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry.

    PubMed

    Sorenson, Gregory P; Schmitt, Adam K; Mahanthappa, Mahesh K

    2014-11-01

    Network phase aqueous lyotropic liquid crystals (LLCs) are technologically useful materials with myriad applications in chemistry, biology, and materials science, which stem from their structurally periodic aqueous and hydrophobic nanodomains (∼0.7-5.0 nm in diameter) that are lined with well-defined chemical functionalities. The exclusive observation of bicontinuous cubic network phase LLCs (e.g., double gyroid, double diamond, and primitive phases) has fueled speculations that all stable LLC network phases must exhibit cubic symmetry. Herein, we describe the self-assembly behavior of a simple aliphatic gemini surfactant that forms the first example of a triply periodic network phase LLC with the 3D-hexagonal symmetry P63/mcm (space group #193). This normal, tetracontinuous 3D-hexagonal network LLC phase HI(193) partitions space into four continuous and interpenetrating, yet non-intersecting volumes. This discovery directly demonstrates that the gemini amphiphile platform furnishes a rational strategy for discovering and stabilizing new, three-dimensionally periodic multiply continuous network phase LLCs with variable symmetries and potentially new applications. PMID:25182008

  6. Nodes Localization in 3D Wireless Sensor Networks Based on Multidimensional Scaling Algorithm

    PubMed Central

    2014-01-01

    In the recent years, there has been a huge advancement in wireless sensor computing technology. Today, wireless sensor network (WSN) has become a key technology for different types of smart environment. Nodes localization in WSN has arisen as a very challenging problem in the research community. Most of the applications for WSN are not useful without a priory known nodes positions. Adding GPS receivers to each node is an expensive solution and inapplicable for indoor environments. In this paper, we implemented and evaluated an algorithm based on multidimensional scaling (MDS) technique for three-dimensional (3D) nodes localization in WSN using improved heuristic method for distance calculation. Using extensive simulations we investigated our approach regarding various network parameters. We compared the results from the simulations with other approaches for 3D-WSN localization and showed that our approach outperforms other techniques in terms of accuracy.

  7. Computer generation and application of 3-D model porous media: From pore-level geostatistics to the estimation of formation factor

    SciTech Connect

    Ioannidis, M.; Kwiecien, M.; Chatzis, I.

    1995-12-31

    This paper describes a new method for the computer generation of 3-D stochastic realizations of porous media using geostatistical information obtained from high-contrast 2-D images of pore casts. The stochastic method yields model porous media with statistical properties identical to those of their real counterparts. Synthetic media obtained in this manner can form the basis for a number of studies related to the detailed characterization of the porous microstructure and, ultimately, the prediction of important petrophysical and reservoir engineering properties. In this context, direct computer estimation of the formation resistivity factor is examined using a discrete random walk algorithm. The dependence of formation factor on measureable statistical properties of the pore space is also investigated.

  8. Formation of Neural Networks in 3D Scaffolds Fabricated by Means of Laser Microstereolithography.

    PubMed

    Vedunova, M V; Timashev, P S; Mishchenko, T A; Mitroshina, E V; Koroleva, A V; Chichkov, B N; Panchenko, V Ya; Bagratashvili, V N; Mukhina, I V

    2016-08-01

    We developed and tested new 3D scaffolds for neurotransplantation. Scaffolds of predetermined architectonic were prepared using microstereolithography technique. Scaffolds were highly biocompatible with the nervous tissue cells. In vitro studies showed that the material of fabricated scaffolds is not toxic for dissociated brain cells and promotes the formation of functional neural networks in the matrix. These results demonstrate the possibility of fabrication of tissue-engineering constructs for neurotransplantation based on created scaffolds. PMID:27595153

  9. Pore-scale modeling of Capillary Penetration of Wetting Liquid into 3D Fibrous Media: A Critical Examination of Equivalent Capillary Concept

    NASA Astrophysics Data System (ADS)

    Palakurthi, Nikhil Kumar; Ghia, Urmila; Comer, Ken

    2013-11-01

    Capillary penetration of liquid through fibrous porous media is important in many applications such as printing, drug delivery patches, sanitary wipes, and performance fabrics. Historically, capillary transport (with a distinct liquid propagating front) in porous media is modeled using capillary-bundle theory. However, it is not clear if the capillary model (Washburn equation) describes the fluid transport in porous media accurately, as it assumes uniformity of pore sizes in the porous medium. The present work investigates the limitations of the applicability of the capillary model by studying liquid penetration through virtual fibrous media with uniform and non-uniform pore-sizes. For the non-uniform-pore fibrous medium, the effective capillary radius of the fibrous medium was estimated from the pore-size distribution curve. Liquid penetration into the 3D virtual fibrous medium at micro-scale was simulated using OpenFOAM, and the numerical results were compared with the Washburn-equation capillary-model predictions. Preliminary results show that the Washburn equation over-predicts the height rise in the early stages (purely inertial and visco-inertial stages) of capillary transport.

  10. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    PubMed Central

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3−/I−) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  11. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    NASA Astrophysics Data System (ADS)

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-03-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3‑/I‑) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization.

  12. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites.

    PubMed

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3(-)/I(-)) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  13. An approach to architecture 3D scaffold with interconnective microchannel networks inducing angiogenesis for tissue engineering.

    PubMed

    Sun, Jiaoxia; Wang, Yuanliang; Qian, Zhiyong; Hu, Chenbo

    2011-11-01

    The angiogenesis of 3D scaffold is one of the major current limitations in clinical practice tissue engineering. The new strategy of construction 3D scaffold with microchannel circulation network may improve angiogenesis. In this study, 3D poly(D: ,L: -lactic acid) scaffolds with controllable microchannel structures were fabricated using sacrificial sugar structures. Melt drawing sugar-fiber network produced by a modified filament spiral winding method was used to form the microchannel with adjustable diameters and porosity. This fabrication process was rapid, inexpensive, and highly scalable. The porosity, microchannel diameter, interconnectivity and surface topographies of the scaffold were characterized by scanning electron microscopy. Mechanical properties were evaluated by compression tests. The mean porosity values of the scaffolds were in the 65-78% and the scaffold exhibited microchannel structure with diameter in the 100-200 μm range. The results showed that the scaffolds exhibited an adequate porosity, interconnective microchannel network, and mechanical properties. The cell culture studies with endothelial cells (ECs) demonstrated that the scaffold allowed cells to proliferate and penetrate into the volume of the entire scaffold. Overall, these findings suggest that the fabrication process offers significant advantages and flexibility in generating a variety of non-cytotoxic tissue engineering scaffolds with controllable distributions of porosity and physical properties that could provide the necessary physical cues for ECs and further improve angiogenesis for tissue engineering. PMID:21861076

  14. 3D MPEG-2 video transmission over broadband network and broadcast channels

    NASA Astrophysics Data System (ADS)

    Gagnon, Gilles; Subramaniam, Suganthan; Vincent, Andre

    2001-06-01

    This paper explores the transmission of MPEG-2 compressed stereoscopic (3-D) video over broadband networks and digital television (DTV) broadcast channels. A system has been developed to perform 3-D (stereoscopic) MPEG-2 video encoding, transmission and decoding over broadband networks in real- time. Such a system can benefit applications where a depiction of the relative positions of objects in 3-dimensional space is critical, by providing visual cues along the sight axis. Applications such as tele-medicine, remote surveillance, tele- education, entertainment and others could benefit from such a system since it conveys an added viewing experience. For simplicity and cost efficiency the system is kept as simple as possible while offering a certain degree of control over the encoding and decoding platforms. Data exchange is done with TCP/IP for control between the server and client and with UDP/IP for the MPEG-2 transport streams delivered to the client. Parameters such as encoding rate can be set independently for the left and right viewing channels to satisfy network bandwidth restrictions, while maintaining satisfactory quality. Using this system, transmission of stereoscopic MPEG-2 transport streams (video and audio) has been performed over a 155 Mbps ATM network shared with other video transactions between server and clients. Preliminary results have shown that the system is reasonably robust to network impairments making it useable in relatively loaded networks. An innovative technique for broadcasting Standard Definition Television 3-D video using an ATSC compatible encoding and broadcasting system is also presented. This technique requires a simple video multiplexer before the ATSC encoding process, and a slight modification at the receiver after the ATSC decoding.

  15. Morphogenesis of 3D vascular networks is regulated by tensile forces.

    PubMed

    Rosenfeld, Dekel; Landau, Shira; Shandalov, Yulia; Raindel, Noa; Freiman, Alina; Shor, Erez; Blinder, Yaron; Vandenburgh, Herman H; Mooney, David J; Levenberg, Shulamit

    2016-03-22

    Understanding the forces controlling vascular network properties and morphology can enhance in vitro tissue vascularization and graft integration prospects. This work assessed the effect of uniaxial cell-induced and externally applied tensile forces on the morphology of vascular networks formed within fibroblast and endothelial cell-embedded 3D polymeric constructs. Force intensity correlated with network quality, as verified by inhibition of force and of angiogenesis-related regulators. Tensile forces during vessel formation resulted in parallel vessel orientation under static stretching and diagonal orientation under cyclic stretching, supported by angiogenic factors secreted in response to each stretch protocol. Implantation of scaffolds bearing network orientations matching those of host abdominal muscle tissue improved graft integration and the mechanical properties of the implantation site, a critical factor in repair of defects in this area. This study demonstrates the regulatory role of forces in angiogenesis and their capacities in vessel structure manipulation, which can be exploited to improve scaffolds for tissue repair. PMID:26951667

  16. 3D position estimation using an artificial neural network for a continuous scintillator PET detector

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhu, W.; Cheng, X.; Li, D.

    2013-03-01

    Continuous crystal based PET detectors have features of simple design, low cost, good energy resolution and high detection efficiency. Through single-end readout of scintillation light, direct three-dimensional (3D) position estimation could be another advantage that the continuous crystal detector would have. In this paper, we propose to use artificial neural networks to simultaneously estimate the plane coordinate and DOI coordinate of incident γ photons with detected scintillation light. Using our experimental setup with an ‘8 + 8’ simplified signal readout scheme, the training data of perpendicular irradiation on the front surface and one side surface are obtained, and the plane (x, y) networks and DOI networks are trained and evaluated. The test results show that the artificial neural network for DOI estimation is as effective as for plane estimation. The performance of both estimators is presented by resolution and bias. Without bias correction, the resolution of the plane estimator is on average better than 2 mm and that of the DOI estimator is about 2 mm over the whole area of the detector. With bias correction, the resolution at the edge area for plane estimation or at the end of the block away from the readout PMT for DOI estimation becomes worse, as we expect. The comprehensive performance of the 3D positioning by a neural network is accessed by the experimental test data of oblique irradiations. To show the combined effect of the 3D positioning over the whole area of the detector, the 2D flood images of oblique irradiation are presented with and without bias correction.

  17. Three-dimensionally networked graphene hydroxide with giant pores and its application in supercapacitors

    NASA Astrophysics Data System (ADS)

    Lee, Dongwook; Seo, Jiwon

    2014-12-01

    The three-dimensionally networked and layered structure of graphene hydroxide (GH) was investigated. After lengthy immersion in a NaOH solution, most of the epoxy groups in the graphene oxide were destroyed, and more hydroxyl groups were generated, transforming the graphene oxide into graphene hydroxide. Additionally, benzoic acid groups were formed, and the ether groups link the neighboring layers, creating a near-3D structure in the GH. To utilize these unique structural features, electrodes with large pores for use in supercapacitors were fabricated using thermal reduction in vacuum. The reduced GH maintained its layered structure and developed a lot of large of pores between/inside the layers. The GH electrodes exhibited high gravimetric as well as high volumetric capacitance.

  18. Three-dimensionally networked graphene hydroxide with giant pores and its application in supercapacitors

    PubMed Central

    Lee, Dongwook; Seo, Jiwon

    2014-01-01

    The three-dimensionally networked and layered structure of graphene hydroxide (GH) was investigated. After lengthy immersion in a NaOH solution, most of the epoxy groups in the graphene oxide were destroyed, and more hydroxyl groups were generated, transforming the graphene oxide into graphene hydroxide. Additionally, benzoic acid groups were formed, and the ether groups link the neighboring layers, creating a near-3D structure in the GH. To utilize these unique structural features, electrodes with large pores for use in supercapacitors were fabricated using thermal reduction in vacuum. The reduced GH maintained its layered structure and developed a lot of large of pores between/inside the layers. The GH electrodes exhibited high gravimetric as well as high volumetric capacitance. PMID:25492227

  19. Structural and property studies on metal–organic compounds with 3-D supramolecular network

    SciTech Connect

    Zhang, Qi-Ying; Ma, Ke-Fang; Xiao, Hong-Ping; Li, Xin-Hua; Shi, Qian

    2014-07-01

    Two carboxylato-bridged allomeric compounds, ([Cu{sub 2}(dbsa){sub 2}(hmt) (H{sub 2}O){sub 4}]{sub 1/2}·2H{sub 2}O){sub n} (1), ([Ni(dbsa)(H{sub 2}O){sub 2}]{sub 1/2}[Ni(dbsa)(hmt)(H{sub 2}O){sub 2}]{sub 1/2}·2H{sub 2}O){sub n} (2) (H{sub 2}dbsa=meso-2,3-dibromosuccinic acid, hmt=hexamethylenetetramine) have been synthesized and characterized by X-ray structral analyses. The metal ions have two kinds of coordination fashion in one unit, and bridged by carboxylate and hmt ligands along with weak interactions existing in the solid structure, forming a 3-D supramolecular network. Variable-temperature magnetic property studies reveal the existence of antiferromagnetic interactions in 1 and 2 with g=2.2, J{sub 1}=−3.5 cm{sup −1}, J{sub 2}=−2.8 cm{sup −1} for 1, and g=2.1, J=−3.5 cm{sup −1} for 2. - Graphical abstract: Variable-temperature magnetic property studies of two 3-D supramolecular compounds reveal the existence of antiferromagnetic interactions between the metal ions, through the effective super-exchange media. - Highlights: • Two 3-D allomeric Cu(II) and Ni(II) metal–organic compounds have been prepared. • The 3-D networks were constructed by coordination bonds, weak interactions and hydrogen bond interactions. • There are antiferromagnetic super-exchange interactions between the metal ions.

  20. 2D and 3D Histioid Disclination Networks in Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Jiang, Miao; Guo, Yubing; Lavrentovich, Oleg; Wei, Qi-Huo

    Topological defects and disclination lines are of both fundamental interest and practical importance. In this paper, we will show that periodic/non-periodic 2D/3D networks of disclination lines can be created in nematic liquid crystal cells by setting well-designed alignment patterns at the top and bottom substrate surfaces. The desired complex patterns of liquid crystal molecular alignments at the substrates are obtained using a projection photoalignment technique based on plasmonic metamasks. The designs of alignment patterns and their resulting disclination line networks will be presented. These designable topological networks represent a new kind of artificial materials which could be of useful for directing colloidal and molecular assembly. National Science Foundation CMMI-1436565.

  1. Accuracy of typical photogrammetric networks in cultural heritage 3D modeling projects

    NASA Astrophysics Data System (ADS)

    Nocerino, E.; Menna, F.; Remondino, F.

    2014-06-01

    The easy generation of 3D geometries (point clouds or polygonal models) with fully automated image-based methods poses nontrivial problems on how to check a posteriori the quality of the achieved results. Clear statements and procedures on how to plan the camera network, execute the survey and use automatic tools to achieve the prefixed requirements are still an open issue. Although such issues had been discussed and solved some years ago, the importance of camera network geometry is today often underestimated or neglected in the cultural heritage field. In this paper different camera network geometries, with normal and convergent images, are analyzed and the accuracy of the produced results are compared to ground truth measurements.

  2. 3D characterization of the fracture network in a deformed chalk reservoir analogue: The Lagerdorf case

    SciTech Connect

    Koestler, A.G.; Reksten, K.

    1994-12-31

    Quantitative descriptions of the 3D fracture networks in terms of connectivity, fracture types, fracture surface roughness and flow characteristics are necessary for reservoir evaluation, management, and enhanced oil recovery programs of fractured reservoirs. For a period of 2 years, a research project focused on an analogue to fractured chalk reservoirs excellently exposed near Laegerdorf, NW Germany. Upper Cretaceous chalk has been uplifted and deformed by an underlying salt diapir, and is now exploited for the cement industry. In the production wall of a quarry, the fracture network of the deformed chalk was characterized and mapped at different scales. The wall was scraped off as chalk exploitation proceeded, continuously revealing new sections through the faulted and fractured chalk body. A 230 m long part of the 35m high production wall was investigated during its recess of 25m. The large amount of fracture data were analyzed with respect to parameters such as fracture density distribution, orientation- and length distribution, and in terms of the representativity of data sets collected from restricted rock volumes. This 3D description and analysis of a fracture network revealed quantitative generic parameters of importance for modeling chalk reservoirs with less data and lower data quality.

  3. Pore-network modeling of biofilm evolution in porous media.

    PubMed

    Ezeuko, C C; Sen, A; Grigoryan, A; Gates, I D

    2011-10-01

    The influence of bacterial biomass on hydraulic properties of porous media (bioclogging) has been explored as a viable means for optimizing subsurface bioremediation and microbial enhanced oil recovery. In this study, we present a pore network simulator for modeling biofilm evolution in porous media including hydrodynamics and nutrient transport based on coupling of advection transport with Fickian diffusion and a reaction term to account for nutrient consumption. Biofilm has non-zero permeability permitting liquid flow and transport through the biofilm itself. To handle simultaneous mass transfer in both liquid and biofilm in a pore element, a dual-diffusion mass transfer model is introduced. The influence of nutrient limitation on predicted results is explored. Nutrient concentration in the network is affected by diffusion coefficient for nutrient transfer across biofilm (compared to water/water diffusion coefficient) under advection dominated transport, represented by mass transport Péclet number >1. The model correctly predicts a dependence of rate of biomass accumulation on inlet concentration. Poor network connectivity shows a significantly large reduction of permeability, for a small biomass pore volume. PMID:21520022

  4. Direct synthesis of graphene 3D-coated Cu nanosilks network for antioxidant transparent conducting electrode

    NASA Astrophysics Data System (ADS)

    Xu, Hongmei; Wang, Huachun; Wu, Chenping; Lin, Na; Soomro, Abdul Majid; Guo, Huizhang; Liu, Chuan; Yang, Xiaodong; Wu, Yaping; Cai, Duanjun; Kang, Junyong

    2015-06-01

    Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 μm length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by the imprint method. A magnetic manipulator equipped with a copper capsule was used to produce high Cu vapor pressure on Cu nanosilks and realize the graphene 3D-coating. The coated Cu@graphene nanosilks network achieved high transparency, low sheet resistance (41 Ohm sq-1 at 95% transmittance) and robust antioxidant ability. With this technique, the transfer process of graphene is no longer needed, and a flexible, uniform and high-performance transparent conducting film could be fabricated in unlimited size.Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 μm length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by

  5. The impact of pore structure and surface roughness on capillary trapping for 2-D and 3-D porous media: Comparison with percolation theory

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Ataei-Dadavi, Iman; Mohammadian, Sadjad; Vogel, Hans-Jörg

    2015-11-01

    We study the impact of pore structure and surface roughness on capillary trapping of nonwetting gas phase during imbibition with water for capillary numbers between 10-7 and 5 × 10-5, within glass beads, natural sands, glass beads monolayers, and 2-D micromodels. The materials exhibit different roughness of the pore-solid interface. We found that glass beads and natural sands, which exhibit nearly the same grain size distribution, pore size distribution, and connectivity, showed a significant difference of the trapped gas phase of about 15%. This difference can be explained by the microstructure of the pore-solid interface. Based on the visualization of the trapping dynamics within glass beads monolayers and 2-D micromodels, we could show that bypass trapping controls the trapping process in glass beads monolayers, while snap-off trapping controls the trapping process in 2-D micromodels. We conclude that these different trapping processes are the reason for the different trapping efficiency, when comparing glass beads packs with natural sand packs. Moreover, for small capillary numbers of 10-6, we found that the cluster size distribution of trapped gas clusters of all 2-D and 3-D porous media can be described by a universal power law behavior predicted from percolation theory. This cannot be expected a priori for 2-D porous media, because bicontinuity of the two bulk phases is violated. Obviously, bicontinuity holds for the thin-film water phase and the bulk gas phase. The snap-off trapping process leads to ordinary bond percolation in front of the advancing bulk water phase and is the reason for the observed universal power law behavior in 2-D micromodels with rough surfaces.

  6. 2D image classification for 3D anatomy localization: employing deep convolutional neural networks

    NASA Astrophysics Data System (ADS)

    de Vos, Bob D.; Wolterink, Jelmer M.; de Jong, Pim A.; Viergever, Max A.; Išgum, Ivana

    2016-03-01

    Localization of anatomical regions of interest (ROIs) is a preprocessing step in many medical image analysis tasks. While trivial for humans, it is complex for automatic methods. Classic machine learning approaches require the challenge of hand crafting features to describe differences between ROIs and background. Deep convolutional neural networks (CNNs) alleviate this by automatically finding hierarchical feature representations from raw images. We employ this trait to detect anatomical ROIs in 2D image slices in order to localize them in 3D. In 100 low-dose non-contrast enhanced non-ECG synchronized screening chest CT scans, a reference standard was defined by manually delineating rectangular bounding boxes around three anatomical ROIs -- heart, aortic arch, and descending aorta. Every anatomical ROI was automatically identified using a combination of three CNNs, each analyzing one orthogonal image plane. While single CNNs predicted presence or absence of a specific ROI in the given plane, the combination of their results provided a 3D bounding box around it. Classification performance of each CNN, expressed in area under the receiver operating characteristic curve, was >=0.988. Additionally, the performance of ROI localization was evaluated. Median Dice scores for automatically determined bounding boxes around the heart, aortic arch, and descending aorta were 0.89, 0.70, and 0.85 respectively. The results demonstrate that accurate automatic 3D localization of anatomical structures by CNN-based 2D image classification is feasible.

  7. Producing 3D neuronal networks in hydrogels for living bionic device interfaces.

    PubMed

    Aregueta-Robles, Ulises A; Lim, Khoon S; Martens, Penny J; Lovell, Nigel H; Poole-Warren, Laura A; Green, Rylie

    2015-08-01

    Hydrogels hold significant promise for supporting cell based therapies in the field of bioelectrodes. It has been proposed that tissue engineering principles can be used to improve the integration of neural interfacing electrodes. Degradable hydrogels based on poly (vinyl alcohol) functionalised with tyramine (PVA-Tyr) have been shown to support covalent incorporation of non-modified tyrosine rich proteins within synthetic hydrogels. PVA-Tyr crosslinked with such proteins, were explored as a scaffold for supporting development of neural tissue in a three dimensional (3D) environment. In this study a model neural cell line (PC12) and glial accessory cell line, Schwann cell (SC) were encapsulated in PVA-Tyr crosslinked with gelatin and sericin. Specifically, this study aimed to examine the growth and function of SC and PC12 co-cultures when translated from a two dimensional (2D) environment to a 3D environment. PC12 differentiation was successfully promoted in both 2D and 3D at 25 days post-culture. SC encapsulated as a single cell line and in co-culture were able to produce both laminin and collagen-IV which are required to support neuronal development. Neurite outgrowth in the 3D environment was confirmed by immunocytochemical staining. PVA-Tyr/sericin/gelatin hydrogel showed mechanical properties similar to nerve tissue elastic modulus. It is suggested that the mechanical properties of the PVA-Tyr hydrogels with native protein components are providing with a compliant substrate that can be used to support the survival and differentiation of neural networks. PMID:26736824

  8. Distributed Network, Wireless and Cloud Computing Enabled 3-D Ultrasound; a New Medical Technology Paradigm

    PubMed Central

    Meir, Arie; Rubinsky, Boris

    2009-01-01

    Medical technologies are indispensable to modern medicine. However, they have become exceedingly expensive and complex and are not available to the economically disadvantaged majority of the world population in underdeveloped as well as developed parts of the world. For example, according to the World Health Organization about two thirds of the world population does not have access to medical imaging. In this paper we introduce a new medical technology paradigm centered on wireless technology and cloud computing that was designed to overcome the problems of increasing health technology costs. We demonstrate the value of the concept with an example; the design of a wireless, distributed network and central (cloud) computing enabled three-dimensional (3-D) ultrasound system. Specifically, we demonstrate the feasibility of producing a 3-D high end ultrasound scan at a central computing facility using the raw data acquired at the remote patient site with an inexpensive low end ultrasound transducer designed for 2-D, through a mobile device and wireless connection link between them. Producing high-end 3D ultrasound images with simple low-end transducers reduces the cost of imaging by orders of magnitude. It also removes the requirement of having a highly trained imaging expert at the patient site, since the need for hand-eye coordination and the ability to reconstruct a 3-D mental image from 2-D scans, which is a necessity for high quality ultrasound imaging, is eliminated. This could enable relatively untrained medical workers in developing nations to administer imaging and a more accurate diagnosis, effectively saving the lives of people. PMID:19936236

  9. Distributed network, wireless and cloud computing enabled 3-D ultrasound; a new medical technology paradigm.

    PubMed

    Meir, Arie; Rubinsky, Boris

    2009-01-01

    Medical technologies are indispensable to modern medicine. However, they have become exceedingly expensive and complex and are not available to the economically disadvantaged majority of the world population in underdeveloped as well as developed parts of the world. For example, according to the World Health Organization about two thirds of the world population does not have access to medical imaging. In this paper we introduce a new medical technology paradigm centered on wireless technology and cloud computing that was designed to overcome the problems of increasing health technology costs. We demonstrate the value of the concept with an example; the design of a wireless, distributed network and central (cloud) computing enabled three-dimensional (3-D) ultrasound system. Specifically, we demonstrate the feasibility of producing a 3-D high end ultrasound scan at a central computing facility using the raw data acquired at the remote patient site with an inexpensive low end ultrasound transducer designed for 2-D, through a mobile device and wireless connection link between them. Producing high-end 3D ultrasound images with simple low-end transducers reduces the cost of imaging by orders of magnitude. It also removes the requirement of having a highly trained imaging expert at the patient site, since the need for hand-eye coordination and the ability to reconstruct a 3-D mental image from 2-D scans, which is a necessity for high quality ultrasound imaging, is eliminated. This could enable relatively untrained medical workers in developing nations to administer imaging and a more accurate diagnosis, effectively saving the lives of people. PMID:19936236

  10. Pore connectivity, electrical conductivity, and partial water saturation: Network simulations

    NASA Astrophysics Data System (ADS)

    Li, M.; Tang, Y. B.; Bernabé, Y.; Zhao, J. Z.; Li, X. F.; Bai, X. Y.; Zhang, L. H.

    2015-06-01

    The electrical conductivity of brine-saturated rock is predominantly dependent on the geometry and topology of the pore space. When a resistive second phase (e.g., air in the vadose zone and oil/gas in hydrocarbon reservoirs) displaces the brine, the geometry and topology of the pore space occupied by the electrically conductive phase are changed. We investigated the effect of these changes on the electrical conductivity of rock partially saturated with brine. We simulated drainage and imbibition as invasion and bond percolation processes, respectively, in pipe networks assumed to be perfectly water-wet. The simulations included the formation of a water film in the pipes invaded by the nonwetting fluid. During simulated drainage/imbibition, we measured the changes in resistivity index as well as a number of relevant microstructural parameters describing the portion of the pore space saturated with water. Except Euler topological number, all quantities considered here showed a significant level of "universality," i.e., insensitivity to the type of lattice used (simple cubic, body-centered cubic, or face-centered cubic). Hence, the coordination number of the pore network appears to be a more effective measure of connectivity than Euler number. In general, the simulated resistivity index did not obey Archie's simple power law. In log-log scale, the resistivity index curves displayed a substantial downward or upward curvature depending on the presence or absence of a water film. Our network simulations compared relatively well with experimental data sets, which were obtained using experimental conditions and procedures consistent with the simulations. Finally, we verified that the connectivity/heterogeneity model proposed by Bernabé et al. (2011) could be extended to the partial brine saturation case when water films were not present.

  11. Clean Synthesis of an Economical 3D Nanochain Network of PdCu Alloy with Enhanced Electrocatalytic Performance towards Ethanol Oxidation.

    PubMed

    Liu, Jiawei; Huang, Zhao; Cai, Kai; Zhang, Huan; Lu, Zhicheng; Li, Tingting; Zuo, Yunpeng; Han, Heyou

    2015-12-01

    A one-pot method for the fast synthesis of a 3D nanochain network (NNC) of PdCu alloy without any surfactants is described. The composition of the as-prepared PdCu alloy catalysts can be precisely controlled by changing the precursor ratio of Pd to Cu. First, the Cu content changes the electronic structure of Pd in the 3D NNC of PdCu alloy. Second, the 3D network structure offers large open pores, high surface areas, and self-supported properties. Third, the surfactant-free strategy results in a relatively clean surface. These factors all contribute to better electrocatalytic activity and durability towards ethanol oxidation. Moreover, the use of copper in the alloy lowers the price of the catalyst by replacing the noble metal palladium with non-noble metal copper. The composition-optimized Pd80 Cu20 alloy in the 3D NNC catalyst shows an increased electrochemically active surface area (80.95 m(2)  g(-1) ) and a 3.62-fold enhancement of mass activity (6.16 A mg(-1) ) over a commercial Pd/C catalyst. PMID:26472208

  12. Analysis of fracture networks in a reservoir dolomite by 3D micro-imaging

    NASA Astrophysics Data System (ADS)

    Voorn, Maarten; Hoyer, Stefan; Exner, Ulrike; Reuschlé, Thierry

    2013-04-01

    Narrow fractures in reservoir rocks can be of great importance when determining the hydrocarbon potential of such a reservoir. Such fractures can contribute significantly to - or even be dominant for - the porosity and permeability characteristics of such rocks. Investigating these narrow fractures is therefore important, but not always trivial. Standard laboratory measurements on sample plugs from a reservoir are not always suitable for fractured rocks. Thin section analysis can provide very important information, but mostly only in 2D. Also other sources of information have major drawbacks, such as FMI (Formation Micro-Imager) during coring (insufficient resolution) and hand specimen analysis (no internal information). 3D imaging of reservoir rock samples is a good alternative and extension to the methods mentioned above. The 3D information is in our case obtained by X-ray Micro-Computed Tomography (µCT) imaging. Our used samples are 2 and 3 cm diameter plugs of a narrowly fractured (apertures generally <200 µm) reservoir dolomite (Hauptdolomit formation) from below the Vienna Basin, Austria. µCT has the large advantage of being non-destructive to the samples, and with the chosen sample sizes and settings, the sample rocks and fractures can be imaged with sufficient quality at sufficient resolution. After imaging, the fracture networks need to be extracted (segmented) from the background. Unfortunately, available segmentation approaches in the literature do not provide satisfactory results on such narrow fractures. We therefore developed the multiscale Hessian fracture filter, with which we are able to extract the fracture networks from the datasets in a better way. The largest advantages of this technique are that it is inherently 3D, runs on desktop computers with limited resources, and is implemented in public domain software (ImageJ / FIJI). The results from the multiscale Hessian fracture filtering approach serve as input for porosity determination. Also

  13. Neural network techniques for invariant recognition and motion tracking of 3-D objects

    SciTech Connect

    Hwang, J.N.; Tseng, Y.H.

    1995-12-31

    Invariant recognition and motion tracking of 3-D objects under partial object viewing are difficult tasks. In this paper, we introduce a new neural network solution that is robust to noise corruption and partial viewing of objects. This method directly utilizes the acquired range data and requires no feature extraction. In the proposed approach, the object is first parametrically represented by a continuous distance transformation neural network (CDTNN) which is trained by the surface points of the exemplar object. When later presented with the surface points of an unknown object, this parametric representation allows the mismatch information to back-propagate through the CDTNN to gradually determine the best similarity transformation (translation and rotation) of the unknown object. The mismatch can be directly measured in the reconstructed representation domain between the model and the unknown object.

  14. Nonthreshold-based event detection for 3d environment monitoring in sensor networks

    SciTech Connect

    Li, M.; Liu, Y.H.; Chen, L.

    2008-12-15

    Event detection is a crucial task for wireless sensor network applications, especially environment monitoring. Existing approaches for event detection are mainly based on some predefined threshold values and, thus, are often inaccurate and incapable of capturing complex events. For example, in coal mine monitoring scenarios, gas leakage or water osmosis can hardly be described by the overrun of specified attribute thresholds but some complex pattern in the full-scale view of the environmental data. To address this issue, we propose a nonthreshold-based approach for the real 3D sensor monitoring environment. We employ energy-efficient methods to collect a time series of data maps from the sensor network and detect complex events through matching the gathered data to spatiotemporal data patterns. Finally, we conduct trace-driven simulations to prove the efficacy and efficiency of this approach on detecting events of complex phenomena from real-life records.

  15. Analysis of transport connectivity in karstic aquifers spanned by 3D conduit networks

    NASA Astrophysics Data System (ADS)

    Ronayne, M. J.

    2013-12-01

    Karst aquifers are characterized by interconnected conduits that behave as structural pathways for groundwater and solutes. This modeling study assesses the influence of conduit network geometry on solute transport behavior within karst systems. Synthetic karst aquifers containing 3D conduit networks were considered. Networks of varying complexity were generated using a directed percolation model. Flow and transport simulations were conducted for each synthetic aquifer by modeling the conduits as discretized high-permeability features within a uniform matrix material. Transport connectivity and dispersive properties were evaluated using statistical moments of the solute arrival time distribution at the downgradient conduit outlet (karst spring). In addition, a new connectivity metric that quantifies solute residence time within conduits was considered. Results show that a more complex network leads to enhanced mixing between the conduit and matrix domains, which has the effect of reducing transport connectivity. This modeling study illustrates how typically available transport data (e.g., solute breakthrough curves at the conduit outlet) may reveal information about the internal network structure, thus providing guidance for future inverse modeling.

  16. Calibration of an Outdoor Distributed Camera Network with a 3D Point Cloud

    PubMed Central

    Ortega, Agustín; Silva, Manuel; Teniente, Ernesto H.; Ferreira, Ricardo; Bernardino, Alexandre; Gaspar, José; Andrade-Cetto, Juan

    2014-01-01

    Outdoor camera networks are becoming ubiquitous in critical urban areas of the largest cities around the world. Although current applications of camera networks are mostly tailored to video surveillance, recent research projects are exploiting their use to aid robotic systems in people-assisting tasks. Such systems require precise calibration of the internal and external parameters of the distributed camera network. Despite the fact that camera calibration has been an extensively studied topic, the development of practical methods for user-assisted calibration that minimize user intervention time and maximize precision still pose significant challenges. These camera systems have non-overlapping fields of view, are subject to environmental stress, and are likely to suffer frequent recalibration. In this paper, we propose the use of a 3D map covering the area to support the calibration process and develop an automated method that allows quick and precise calibration of a large camera network. We present two cases of study of the proposed calibration method: one is the calibration of the Barcelona Robot Lab camera network, which also includes direct mappings (homographies) between image coordinates and world points in the ground plane (walking areas) to support person and robot detection and localization algorithms. The second case consist of improving the GPS positioning of geo-tagged images taken with a mobile device in the Facultat de Matemàtiques i Estadística (FME) patio at the Universitat Politècnica de Catalunya (UPC). PMID:25076221

  17. Calibration of an outdoor distributed camera network with a 3D point cloud.

    PubMed

    Ortega, Agustín; Silva, Manuel; Teniente, Ernesto H; Ferreira, Ricardo; Bernardino, Alexandre; Gaspar, José; Andrade-Cetto, Juan

    2014-01-01

    Outdoor camera networks are becoming ubiquitous in critical urban areas of the largest cities around the world. Although current applications of camera networks are mostly tailored to video surveillance, recent research projects are exploiting their use to aid robotic systems in people-assisting tasks. Such systems require precise calibration of the internal and external parameters of the distributed camera network. Despite the fact that camera calibration has been an extensively studied topic, the development of practical methods for user-assisted calibration that minimize user intervention time and maximize precision still pose significant challenges. These camera systems have non-overlapping fields of view, are subject to environmental stress, and are likely to suffer frequent recalibration. In this paper, we propose the use of a 3D map covering the area to support the calibration process and develop an automated method that allows quick and precise calibration of a large camera network. We present two cases of study of the proposed calibration method: one is the calibration of the Barcelona Robot Lab camera network, which also includes direct mappings (homographies) between image coordinates and world points in the ground plane (walking areas) to support person and robot detection and localization algorithms. The second case consist of improving the GPS positioning of geo-tagged images taken with a mobile device in the Facultat de Matemàtiques i Estadística (FME) patio at the Universitat Politècnica de Catalunya (UPC). PMID:25076221

  18. Visualisation of BioPAX Networks using BioLayout Express 3D

    PubMed Central

    Wright, Derek W.; Angus, Tim; Enright, Anton J.; Freeman, Tom C.

    2014-01-01

    BioLayout Express 3D is a network analysis tool designed for the visualisation and analysis of graphs derived from biological data. It has proved to be powerful in the analysis of gene expression data, biological pathways and in a range of other applications. In version 3.2 of the tool we have introduced the ability to import, merge and display pathways and protein interaction networks available in the BioPAX Level 3 standard exchange format. A graphical interface allows users to search for pathways or interaction data stored in the Pathway Commons database. Queries using either gene/protein or pathway names are made via the cPath2 client and users can also define the source and/or species of information that they wish to examine. Data matching a query are listed and individual records may be viewed in isolation or merged using an ‘Advanced’ query tab. A visualisation scheme has been defined by mapping BioPAX entity types to a range of glyphs. Graphs of these data can be viewed and explored within BioLayout as 2D or 3D graph layouts, where they can be edited and/or exported for visualisation and editing within other tools. PMID:25949802

  19. Visualisation of BioPAX Networks using BioLayout Express (3D).

    PubMed

    Wright, Derek W; Angus, Tim; Enright, Anton J; Freeman, Tom C

    2014-01-01

    BioLayout Express (3D) is a network analysis tool designed for the visualisation and analysis of graphs derived from biological data. It has proved to be powerful in the analysis of gene expression data, biological pathways and in a range of other applications. In version 3.2 of the tool we have introduced the ability to import, merge and display pathways and protein interaction networks available in the BioPAX Level 3 standard exchange format. A graphical interface allows users to search for pathways or interaction data stored in the Pathway Commons database. Queries using either gene/protein or pathway names are made via the cPath2 client and users can also define the source and/or species of information that they wish to examine. Data matching a query are listed and individual records may be viewed in isolation or merged using an 'Advanced' query tab. A visualisation scheme has been defined by mapping BioPAX entity types to a range of glyphs. Graphs of these data can be viewed and explored within BioLayout as 2D or 3D graph layouts, where they can be edited and/or exported for visualisation and editing within other tools. PMID:25949802

  20. Direct synthesis of graphene 3D-coated Cu nanosilks network for antioxidant transparent conducting electrode.

    PubMed

    Xu, Hongmei; Wang, Huachun; Wu, Chenping; Lin, Na; Soomro, Abdul Majid; Guo, Huizhang; Liu, Chuan; Yang, Xiaodong; Wu, Yaping; Cai, Duanjun; Kang, JunYong

    2015-06-28

    Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 μm length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by the imprint method. A magnetic manipulator equipped with a copper capsule was used to produce high Cu vapor pressure on Cu nanosilks and realize the graphene 3D-coating. The coated Cu@graphene nanosilks network achieved high transparency, low sheet resistance (41 Ohm sq(-1) at 95% transmittance) and robust antioxidant ability. With this technique, the transfer process of graphene is no longer needed, and a flexible, uniform and high-performance transparent conducting film could be fabricated in unlimited size. PMID:26018299

  1. A streamline splitting pore-network approach for computationally inexpensive and accurate simulation of transport in porous media

    NASA Astrophysics Data System (ADS)

    Mehmani, Yashar; Oostrom, Mart; Balhoff, Matthew T.

    2014-03-01

    Several approaches have been developed in the literature for solving flow and transport at the pore scale. Some authors use a direct modeling approach where the fundamental flow and transport equations are solved on the actual pore-space geometry. Such direct modeling, while very accurate, comes at a great computational cost. Network models are computationally more efficient because the pore-space morphology is approximated. Typically, a mixed cell method (MCM) is employed for solving the flow and transport system which assumes pore-level perfect mixing. This assumption is invalid at moderate to high Peclet regimes. In this work, a novel Eulerian perspective on modeling flow and transport at the pore scale is developed. The new streamline splitting method (SSM) allows for circumventing the pore-level perfect-mixing assumption, while maintaining the computational efficiency of pore-network models. SSM was verified with direct simulations and validated against micromodel experiments; excellent matches were obtained across a wide range of pore-structure and fluid-flow parameters. The increase in the computational cost from MCM to SSM is shown to be minimal, while the accuracy of SSM is much higher than that of MCM and comparable to direct modeling approaches. Therefore, SSM can be regarded as an appropriate balance between incorporating detailed physics and controlling computational cost. The truly predictive capability of the model allows for the study of pore-level interactions of fluid flow and transport in different porous materials. In this paper, we apply SSM and MCM to study the effects of pore-level mixing on transverse dispersion in 3-D disordered granular media.

  2. A streamline splitting pore-network approach for computationally inexpensive and accurate simulation of transport in porous media

    SciTech Connect

    Mehmani, Yashar; Oostrom, Martinus; Balhoff, Matthew

    2014-03-20

    Several approaches have been developed in the literature for solving flow and transport at the pore-scale. Some authors use a direct modeling approach where the fundamental flow and transport equations are solved on the actual pore-space geometry. Such direct modeling, while very accurate, comes at a great computational cost. Network models are computationally more efficient because the pore-space morphology is approximated. Typically, a mixed cell method (MCM) is employed for solving the flow and transport system which assumes pore-level perfect mixing. This assumption is invalid at moderate to high Peclet regimes. In this work, a novel Eulerian perspective on modeling flow and transport at the pore-scale is developed. The new streamline splitting method (SSM) allows for circumventing the pore-level perfect mixing assumption, while maintaining the computational efficiency of pore-network models. SSM was verified with direct simulations and excellent matches were obtained against micromodel experiments across a wide range of pore-structure and fluid-flow parameters. The increase in the computational cost from MCM to SSM is shown to be minimal, while the accuracy of SSM is much higher than that of MCM and comparable to direct modeling approaches. Therefore, SSM can be regarded as an appropriate balance between incorporating detailed physics and controlling computational cost. The truly predictive capability of the model allows for the study of pore-level interactions of fluid flow and transport in different porous materials. In this paper, we apply SSM and MCM to study the effects of pore-level mixing on transverse dispersion in 3D disordered granular media.

  3. 3D geological model developed to analyse the aquifer - sewer network interaction in Bucharest city

    NASA Astrophysics Data System (ADS)

    Serpescu, I.; Radu, E.; Gogu, R. G.; Priceputu, A.; Boukhemacha, M. A.; Bica, I.; Gaitanaru, D.

    2012-04-01

    Due to the fact that several important Bucharest city sewer segments drain the groundwater and provide high input flow-rates for the existing waste-water treatment plant, their rehabilitation is necessary. A hydrogeological model, currently under development, will permit to compute the groundwater-sewer network interaction allowing the simulation of distinct design solutions to prevent city disturbances. For groundwater modelling the geological model represents the fundament of understanding the aquifers system behaviour. In this respect a 3D accurate and detailed geological model, covering a region of about 75 km2 has been developed to identify its contact with the major collecting sewer conduit. The shallow aquifer stratum of quaternary formations called Colentina is made of gravels and sands. This unconfined aquifer can be found mainly in the Bucharest city region at depths up to 20 m. A clayey-marl layer is located between Colentina and a lower confined aquifer called Mostistea. This second one is located at depths between 25 m and 70 m and is made of fine and medium sands with gravel intercalations. It overlays on a very thick sequence (40 m to 150 m) of marl and clay layers with slim sandy intercalations. The geological model has been developed on the basis of a large number of geological and geotechnical boreholes. A set of 400 boreholes with depths between 5m to 200 m showing a detailed geological and lithological description stored in a geospatial database have been used. The geological analysis has been performed using a software platform that integrates the spatial database and a set of tools and methodologies developed in a GIS environment with the aim of facilitating the development of 3D geological models for sedimentary media. Taking into account the first 50 m in depth, 25 geological profiles have been interpreted on the basis of chronostratigraphycal, lithological, and sedimentological criteria to delineate the geological formations and assess

  4. Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo

    PubMed Central

    Pan, Yingtian; You, Jiang; Volkow, Nora D.; Park, Ki; Du, Congwu

    2014-01-01

    Despite widespread applications of multiphoton microscopy in microcirculation, its small field of view and inability to instantaneously quantify cerebral blood flow velocity (CBFv) in vascular networks limit its utility in investigating the heterogeneous responses to brain stimulations. Optical Doppler tomography (ODT) provides 3D images of CBFv networks, but it suffers poor sensitivity for measuring capillary flows. Here we report a new method, contrast-enhanced ODT with intralipid that significantly improves quantitative CBFv imaging of capillary networks by obviating the errors from long latency between flowing red blood cells (low hematocrit ~20% in capillaries). This enhanced sensitivity allowed us to measure the ultraslow microcirculation surrounding a brain tumor and the abnormal ingrowth of capillary flows in the tumor as well as in ischemia triggered by chronic cocaine in the mouse brain that could not be detected by regular ODT. It also enabled significantly enhanced sensitivity for quantifying the heterogeneous CBFv responses of vascular networks to acute cocaine. Inasmuch as intralipids are widely used for parenteral nutrition the intralipid contrast method has translational potential for clinical applications. PMID:25192654

  5. Influence of fracture scale heterogeneity on the flow properties of 3D Discrete Fracture Networks (DFN)

    NASA Astrophysics Data System (ADS)

    Meheust, Y.; De Dreuzy, J.; Pichot, G.

    2011-12-01

    Flow channeling and permeability scaling in fractured media have been classically addressed either at the fracture- or at the network- scales. In the latter case they are linked to the topological structure of the network, while at the fracture scale they are controlled by the variability of the local aperture distribution inside individual fractures. In this study we analyze these two combined effects, investigating how flow localization below the scale of individual fractures influences that at the network scale and the resulting medium permeability. This is done by use of a new highly-resolved 3D discrete fracture network model (DFN). The local apertures of individual fractures are distributed according to a truncated Gaussian law, and exhibit self-affine spatial correlations that are bounded by an upper cutoff scale Lc; Lc and the fracture closure, defined as the ratio of the aperture fluctuations at scale Lc to the mean aperture, are considered homogeneous over the DFN. The network topology is controlled by a homogeneous scalar fracture density and a power law fracture length distribution. We have varied these features to investigate a large variety of DFN topologies, from sparse networks with varying degrees of fracture interconnections, flow bottlenecks and dead-ends (Fig. 1a), to dense well-connected networks (Fig. 1b). We have also investigated a large range of fracture closures, performing extensive simulations of about 105 different DFN realizations. At the fracture scale, accounting for local aperture fluctuations leads to a monotical deviation (which can exceed 50%) of the equivalent fracture transmissivity from the parallel plate behavior. At the network scale we observe a complex interaction between flow channeling within fracture planes and flow localization in the network. This interaction is controlled by the location of fracture interactions with respect to that of low local transmissivity zones (particularly the closed zones), in the fracture

  6. Texture analysis of the 3D collagen network and automatic classification of the physiology of articular cartilage.

    PubMed

    Duan, Xiaojuan; Wu, Jianping; Swift, Benjamin; Kirk, Thomas Brett

    2015-07-01

    A close relationship has been found between the 3D collagen structure and physiological condition of articular cartilage (AC). Studying the 3D collagen network in AC offers a way to determine the condition of the cartilage. However, traditional qualitative studies are time consuming and subjective. This study aims to develop a computer vision-based classifier to automatically determine the condition of AC tissue based on the structural characteristics of the collagen network. Texture analysis was applied to quantitatively characterise the 3D collagen structure in normal (International Cartilage Repair Society, ICRS, grade 0), aged (ICRS grade 1) and osteoarthritic cartilages (ICRS grade 2). Principle component techniques and linear discriminant analysis were then used to classify the microstructural characteristics of the 3D collagen meshwork and the condition of the AC. The 3D collagen meshwork in the three physiological condition groups displayed distinctive characteristics. Texture analysis indicated a significant difference in the mean texture parameters of the 3D collagen network between groups. The principle component and linear discriminant analysis of the texture data allowed for the development of a classifier for identifying the physiological status of the AC with an expected prediction error of 4.23%. An automatic image analysis classifier has been developed to predict the physiological condition of AC (from ICRS grade 0 to 2) based on texture data from the 3D collagen network in the tissue. PMID:24428581

  7. Creating 3D chemical gradients with self-folding microfluidic networks

    NASA Astrophysics Data System (ADS)

    Jamal, Mustapha; Kalinin, Yevgeniy; Zarafshar, Aasiyeh; Gracias, David

    2012-02-01

    We describe the reversible self-folding of polymeric films into intricate three-dimensional (3D) microfluidic networks and investigate their utility as bio-inspired synthetic vasculature for in vitro tissue culture models. Our fabrication methodology relies on patterning of channels inside the films at the planar microfabrication stage followed by programmable self-folding of the two-dimensional patterned structures. Here self-folding action is enabled by stress gradients which develop in the films due to differential ultraviolet cross-linking and subsequent solvent conditioning. We achieved wafer-scale assembly of micropatterned geometries including helices, polyhedra and corrugated sheets. To demonstrate utility of such self-folded microfluidic devices we present localized chemical delivery of biochemicals in 3D to discrete regions of cells cultured on the curved self-assembled surfaces and in a thick, surrounding hydrogel. We believe that the devices can be used to mimic such natural self-assembled systems as leaves and tissues. Reference: M. Jamal et al., Nature Communications (2011; in press).

  8. Novel enzymatically cross-linked hyaluronan hydrogels support the formation of 3D neuronal networks.

    PubMed

    Broguiere, Nicolas; Isenmann, Luca; Zenobi-Wong, Marcy

    2016-08-01

    Hyaluronan (HA) is an essential component of the central nervous system's extracellular matrix and its high molecular weight (MW) form has anti-inflammatory and anti-fibrotic properties relevant for regenerative medicine. Here, we introduce a new hydrogel based on high MW HA which is cross-linked using the transglutaminase (TG) activity of the activated blood coagulation factor XIII (FXIIIa). These HA-TG gels have significant advantages for neural tissue engineering compared to previous HA gels. Due to their chemical inertness in the absence of FXIIIa, the material can be stored long-term, is stable in solution, and shows no cytotoxicity. The gelation is completely cell-friendly due to the specificity of the enzyme and the gelation rate can be tuned from seconds to hours at physiological pH and independently of stiffness. The gels are injectable, and attach covalently to fibrinogen and fibrin, two common bioactive components in in vitro tissue engineering, as well as proteins present in vivo, allowing the gels to covalently bind to brain or spinal cord defects. These optimal chemical and bioactive properties of HA-TG gels enabled the formation of 3D neuronal cultures of unprecedented performance, showing fast neurite outgrowth, axonal and dendritic speciation, strong synaptic connectivity in 3D networks, and rapidly-occurring and long-lasting coordinated electrical activity. PMID:27209262

  9. 3D reconstruction of carbon nanotube networks from neutron scattering experiments

    NASA Astrophysics Data System (ADS)

    Mahdavi, Mostafa; Baniassadi, Majid; Baghani, Mostafa; Dadmun, Mark; Tehrani, Mehran

    2015-09-01

    Structure reconstruction from statistical descriptors, such as scattering data obtained using x-rays or neutrons, is essential in understanding various properties of nanocomposites. Scattering based reconstruction can provide a realistic model, over various length scales, that can be used for numerical simulations. In this study, 3D reconstruction of a highly loaded carbon nanotube (CNT)-conducting polymer system based on small and ultra-small angle neutron scattering (SANS and USANS, respectively) data was performed. These light-weight and flexible materials have recently shown great promise for high-performance thermoelectric energy conversion, and their further improvement requires a thorough understanding of their structure-property relationships. The first step in achieving such understanding is to generate models that contain the hierarchy of CNT networks over nano and micron scales. The studied system is a single walled carbon nanotube (SWCNT)/poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS). SANS and USANS patterns of the different samples containing 10, 30, and 50 wt% SWCNTs were measured. These curves were then utilized to calculate statistical two-point correlation functions of the nanostructure. These functions along with the geometrical information extracted from SANS data and scanning electron microscopy images were used to reconstruct a representative volume element (RVE) nanostructure. Generated RVEs can be used for simulations of various mechanical and physical properties. This work, therefore, introduces a framework for the reconstruction of 3D RVEs of high volume faction nanocomposites containing high aspect ratio fillers from scattering experiments.

  10. Control of vascular network location in millimeter-sized 3D-tissues by micrometer-sized collagen coated cells.

    PubMed

    Liu, Chun-Yen; Matsusaki, Michiya; Akashi, Mitsuru

    2016-03-25

    Engineering three-dimensional (3D) vascularized constructs remains a central challenge because capillary network structures are important for sufficient oxygen and nutrient exchange to sustain the viability of engineered constructs. However, construction of 3D-tissues at single cell level has yet to be reported. Previously, we established a collagen coating method for fabricating a micrometer-sized collagen matrix on cell surfaces to control cell distance or cell densities inside tissues. In this study, a simple fabrication method is presented for constructing vascular networks in 3D-tissues over micrometer-sized or even millimeter-sized with controlled cell densities. From the results, well vascularized 3D network structures can be observed with a fluorescence label method mixing collagen coated cells and endothelia cells, indicating that constructed ECM rich tissues have the potential for vascularization, which opens up the possibility for various applications in pharmaceutical or tissue engineering fields. PMID:26920051

  11. Nonlinear transport of soft droplets in pore networks

    NASA Astrophysics Data System (ADS)

    Vernerey, Franck; Benet Cerda, Eduard; Koo, Kanghyeon

    A large number of biological and technological processes depend on the transport of soft colloidal particles through porous media; this includes the transport and separation of cells, viruses or drugs through tissues, membranes and microfluidic devices. In these systems, the interactions between soft particles, background fluid and the surrounding pore space yield complex, nonlinear behaviors such as non-Darcy flows, localization and jamming. We devise a computational strategy to investigate the transport of non-wetting and deformable water droplets in a microfluidic device made of a random distribution of cylindrical obstacles. We first derive scaling laws for the entry of the droplet in a single pore and discuss the role of surface tension, contact angle and size in this process. This information is then used to study the transport of multiple droplets in an obstacle network. We find that when the droplet size is close to the pore size, fluid flow and droplet trafficking strongly interact, leading to local redistributions in pressure fields, intermittent clogging and jamming. Importantly, it is found that the overall droplet and fluid transport display three different scaling regimes depending on the forcing pressure, and that these regimes can be related to droplet properties.

  12. Models and simulation of 3D neuronal dendritic trees using Bayesian networks.

    PubMed

    López-Cruz, Pedro L; Bielza, Concha; Larrañaga, Pedro; Benavides-Piccione, Ruth; DeFelipe, Javier

    2011-12-01

    Neuron morphology is crucial for neuronal connectivity and brain information processing. Computational models are important tools for studying dendritic morphology and its role in brain function. We applied a class of probabilistic graphical models called Bayesian networks to generate virtual dendrites from layer III pyramidal neurons from three different regions of the neocortex of the mouse. A set of 41 morphological variables were measured from the 3D reconstructions of real dendrites and their probability distributions used in a machine learning algorithm to induce the model from the data. A simulation algorithm is also proposed to obtain new dendrites by sampling values from Bayesian networks. The main advantage of this approach is that it takes into account and automatically locates the relationships between variables in the data instead of using predefined dependencies. Therefore, the methodology can be applied to any neuronal class while at the same time exploiting class-specific properties. Also, a Bayesian network was defined for each part of the dendrite, allowing the relationships to change in the different sections and to model heterogeneous developmental factors or spatial influences. Several univariate statistical tests and a novel multivariate test based on Kullback-Leibler divergence estimation confirmed that virtual dendrites were similar to real ones. The analyses of the models showed relationships that conform to current neuroanatomical knowledge and support model correctness. At the same time, studying the relationships in the models can help to identify new interactions between variables related to dendritic morphology. PMID:21305364

  13. Regional application of multi-layer artificial neural networks in 3-D ionosphere tomography

    NASA Astrophysics Data System (ADS)

    Ghaffari Razin, Mir Reza; Voosoghi, Behzad

    2016-08-01

    Tomography is a very cost-effective method to study physical properties of the ionosphere. In this paper, residual minimization training neural network (RMTNN) is used in voxel-based tomography to reconstruct of 3-D ionosphere electron density with high spatial resolution. For numerical experiments, observations collected at 37 GPS stations from Iranian permanent GPS network (IPGN) are used. A smoothed TEC approach was used for absolute STEC recovery. To improve the vertical resolution, empirical orthogonal functions (EOFs) obtained from international reference ionosphere 2012 (IRI-2012) used as object function in training neural network. Ionosonde observations is used for validate reliability of the proposed method. Minimum relative error for RMTNN is 1.64% and maximum relative error is 15.61%. Also root mean square error (RMSE) of 0.17 × 1011 (electrons/m3) is computed for RMTNN which is less than RMSE of IRI2012. The results show that RMTNN has higher accuracy and compiles speed than other ionosphere reconstruction methods.

  14. Multi-static networked 3D ladar for surveillance and access control

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Ogirala, S. S. R.; Hu, B.; Le, Han Q.

    2007-04-01

    A theoretical design and simulation of a 3D ladar system concept for surveillance, intrusion detection, and access control is described. It is a non-conventional system architecture that consists of: i) multi-static configuration with an arbitrarily scalable number of transmitters (Tx's) and receivers (Rx's) that form an optical wireless code-division-multiple-access (CDMA) network, and ii) flexible system architecture with modular plug-and-play components that can be deployed for any facility with arbitrary topology. Affordability is a driving consideration; and a key feature for low cost is an asymmetric use of many inexpensive Rx's in conjunction with fewer Tx's, which are generally more expensive. The Rx's are spatially distributed close to the surveyed area for large coverage, and capable of receiving signals from multiple Tx's with moderate laser power. The system produces sensing information that scales as NxM, where N, M are the number of Tx's and Rx's, as opposed to linear scaling ~N in non-network system. Also, for target positioning, besides laser pointing direction and time-of-flight, the algorithm includes multiple point-of-view image fusion and triangulation for enhanced accuracy, which is not applicable to non-networked monostatic ladars. Simulation and scaled model experiments on some aspects of this concept are discussed.

  15. In situ generation of silver nanoparticles within crosslinked 3D guar gum networks for catalytic reduction.

    PubMed

    Zheng, Yian; Zhu, Yongfeng; Tian, Guangyan; Wang, Aiqin

    2015-02-01

    The direct use of guar gum (GG) as a green reducing agent for the facile production of highly stable silver nanoparticles (Ag NPs) within this biopolymer and subsequent crosslinking with borax to form crosslinked Ag@GG beads with a 3D-structured network are presented here. These crosslinked Ag@GG beads were characterized using UV-vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy, and then tested as a solid-phase heterogenerous catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess borohydride. The results indicate that these crosslinked Ag@GG beads show excellent catalytic performance for the reduction of 4-NP within 20 min and can be readily used for 10 successive cycles. PMID:25445685

  16. Distributed network of integrated 3D sensors for transportation security applications

    NASA Astrophysics Data System (ADS)

    Hejmadi, Vic; Garcia, Fred

    2009-05-01

    The US Port Security Agency has strongly emphasized the needs for tighter control at transportation hubs. Distributed arrays of miniature CMOS cameras are providing some solutions today. However, due to the high bandwidth required and the low valued content of such cameras (simple video feed), large computing power and analysis algorithms as well as control software are needed, which makes such an architecture cumbersome, heavy, slow and expensive. We present a novel technique by integrating cheap and mass replicable stealth 3D sensing micro-devices in a distributed network. These micro-sensors are based on conventional structures illumination via successive fringe patterns on the object to be sensed. The communication bandwidth between each sensor remains very small, but is of very high valued content. Key technologies to integrate such a sensor are digital optics and structured laser illumination.

  17. Hydration State and Aqueous Phase Connectivity Shape Microbial Dispersal Rates in Unsaturated Angular Pore Networks

    NASA Astrophysics Data System (ADS)

    Or, D.; Ebrahimi, A.

    2014-12-01

    The limited dispersal of self-propelled microorganisms and constrained nutrient transport in unsaturated soils are considered key factors in the promotion and maintenance of soil microbial diversity. Despite the importance of microbial dispersal to biogeochemical and ecological functioning of soil, little is known about how pore spaces and hydration conditions affect dispersal ranges and rates of motile bacteria. To address these questions quantitatively, we developed a novel 3-D pore network model (PNM) composed of triangular bonds connected to cubic (volumeless) bonds to mimic the salient geometrical and physical properties of natural pore spaces. Within this abstracted physical domain we employed individual based models for motile microorganisms that are capable of motion, nutrient consumption, growth and cell division. We focused on dispersal rates through the network as a function of hydration conditions through its impact on aqueous phase fragmentation that suppress nutrient diffusion (hence growth rates) and dispersal rates in good agreement with limited experimental data. Chemotactically-biased mean travel rates of microbial cells across the saturated PNM was ~3 mm/hr and decreased exponentially to 0.45 mm/hr for matric potential of (at dispersal practically ceases and cells are pinned by capillary forces). Individual-based results were upscaled to describe population scale dispersal rates, and PNM predictions considering different microbial cell sizes were in good agreement with experimental results for unsaturated soils. The role of convection for most unsaturated conditions was negligible relative to self-motility highlighting the need to constrain continuum models with respect to cell size and motility to imporve predictions of transport of motile microorganisms. The modeling platform confirms universal predictions based on percolation theory for the onset of aqueous phase fragmentation that limit dispersal and provide niches essential for species

  18. Mapping the 3D Connectivity of the Rat Inner Retinal Vascular Network Using OCT Angiography

    PubMed Central

    Leahy, Conor; Radhakrishnan, Harsha; Weiner, Geoffrey; Goldberg, Jeffrey L.; Srinivasan, Vivek J.

    2015-01-01

    Purpose The purpose of this study is to demonstrate three-dimensional (3D) graphing based on optical coherence tomography (OCT) angiography for characterization of the inner retinal vascular architecture and determination of its topologic principles. Methods Rat eyes (N = 3) were imaged with a 1300-nm spectral/Fourier domain OCT microscope. A topologic model of the inner retinal vascular network was obtained from OCT angiography data using a combination of automated and manually-guided image processing techniques. Using a resistive network model, with experimentally-quantified flow in major retinal vessels near the optic nerve head as boundary conditions, theoretical changes in the distribution of flow induced by vessel dilations were inferred. Results A topologically-representative 3D vectorized graph of the inner retinal vasculature, derived from OCT angiography data, is presented. The laminar and compartmental connectivity of the vasculature are characterized. In contrast to sparse connectivity between the superficial vitreal vasculature and capillary plexuses of the inner retina, connectivity between the two capillary plexus layers is dense. Simulated dilation of single arterioles is shown to produce both localized and lamina-specific changes in blood flow, while dilation of capillaries in a given retinal vascular layer is shown to lead to increased total flow in that layer. Conclusions Our graphing and modeling data suggest that vascular architecture enables both local and lamina-specific control of blood flow in the inner retina. The imaging, graph analysis, and modeling approach presented here will help provide a detailed characterization of vascular changes in a variety of retinal diseases, both in experimental preclinical models and human subjects. PMID:26325417

  19. A new electrical formation factor model for bimodal carbonates: numerical studies using dual-pore percolation network

    NASA Astrophysics Data System (ADS)

    Tang, Y. B.; Li, M.; Bernabé, Y.; Tang, H. M.; Li, X. F.; Bai, X. Y.; Tao, Z. W.

    2015-06-01

    In this paper, we modelled the electrical transport behaviour of bimodal carbonate rocks from a reservoir in China using dual-pore networks. One basic assumption, generally supported by experimental data and microstructure observations in the reservoir samples, was that the low porosity, monomodal rocks had the same properties and structure as the microporous matrix of the high porosity, bimodal samples. We assumed that the matrix was homogeneous and always interconnected but that the connectivity and the pore size distribution of macropore system was randomly variable. Both pore systems were supposed to act locally as `in parallel' electrical conductors, an approach previously used by Bauer et al. Hence, the effect of matrix properties, macropore size distribution and connectivity on electrical properties of bimodal rocks could be modelled and investigated. We simulated electrical current through 3-D, simple cubic and body-centred cubic networks with different coordination numbers, different pipe radius distributions of macropore system and different matrix properties. The main result was that the formation factor of dual-pore network obeyed a `universal' scaling relationship (i.e. independent of lattice type). Based on this result, we extended the power-law model derived by Bernabé et al. for monomodal porous media. We developed methods for evaluating the scale-invariant pore structure parameters in the model using conventional core analysis and satisfactorily tested the proposed model against experimental data from the Chinese reservoir as well as some other previously published data sets.

  20. Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

    SciTech Connect

    Li, Ming; Kang, Zhan; Huang, Xiaobo

    2015-08-28

    Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials.

  1. Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Li, Ming; Huang, Xiaobo; Kang, Zhan

    2015-08-01

    Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials.

  2. Fracture-network 3D characterization in a deformed chalk reservoir analogue -- the Laegerdorf case

    SciTech Connect

    Koestler, A.G.; Reksten, K.

    1995-09-01

    Quantitative descriptions of 3D fracture networks in terms of fracture characteristics and connectivity are necessary for reservoir evaluation, management, and EOR programs of fractured reservoirs. The author`s research has focused on an analogue to North Sea fractured chalk reservoirs that is excellently exposed near Laegerdorf, northwest Germany. An underlying salt diapir uplifted and deformed Upper Cretaceous chalk; the cement industry now exploits it. The fracture network in the production wall of the quarry was characterized and mapped at different scales, and 12 profiles of the 230-m wide and 35-m high production wall were investigated as the wall receded 25 m. In addition, three wells were drilled into the chalk volume. The wells were cored and the wellbores were imaged with both the resistivity formation micro scanner (FMS) and the sonic circumferential borehole image logger (CBIL). The large amount of fracture data was analyzed with respect to parameters, such as fracture density distribution, orientation, and length distribution, and in terms of the representativity and predictability of data sets collected from restricted rock volumes.

  3. Pore-network study of the characteristic periods in the drying of porous materials.

    PubMed

    Yiotis, Andreas G; Tsimpanogiannis, Ioannis N; Stubos, Athanassios K; Yortsos, Yannis C

    2006-05-15

    We study the periods that develop in the drying of capillary porous media, particularly the constant rate (CRP) and the falling rate (FRP) periods. Drying is simulated with a 3-D pore-network model that accounts for the effect of capillarity and buoyancy at the liquid-gas interface and for diffusion through the porous material and through a boundary layer over the external surface of the material. We focus on the stabilizing or destabilizing effects of gravity on the shape of the drying curve and the relative extent of the various drying periods. The extents of CRP and FRP are directly associated with various transition points of the percolation theory, such as the breakthrough point and the main liquid cluster disconnection point. Our study demonstrates that when an external diffusive layer is present, the constant rate period is longer. PMID:16359693

  4. APEnet+: a 3D Torus network optimized for GPU-based HPC Systems

    NASA Astrophysics Data System (ADS)

    Ammendola, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Lonardo, A.; Paolucci, P. S.; Rossetti, D.; Simula, F.; Tosoratto, L.; Vicini, P.

    2012-12-01

    In the supercomputing arena, the strong rise of GPU-accelerated clusters is a matter of fact. Within INFN, we proposed an initiative — the QUonG project — whose aim is to deploy a high performance computing system dedicated to scientific computations leveraging on commodity multi-core processors coupled with latest generation GPUs. The inter-node interconnection system is based on a point-to-point, high performance, low latency 3D torus network which is built in the framework of the APEnet+ project. It takes the form of an FPGA-based PCIe network card exposing six full bidirectional links running at 34 Gbps each that implements the RDMA protocol. In order to enable significant access latency reduction for inter-node data transfer, a direct network-to-GPU interface was built. The specialized hardware blocks, integrated in the APEnet+ board, provide support for GPU-initiated communications using the so called PCIe peer-to-peer (P2P) transactions. This development is made in close collaboration with the GPU vendor NVIDIA. The final shape of a complete QUonG deployment is an assembly of standard 42U racks, each one capable of 80 TFLOPS/rack of peak performance, at a cost of 5 k€/T F LOPS and for an estimated power consumption of 25 kW/rack. In this paper we report on the status of final rack deployment and on the R&D activities for 2012 that will focus on performance enhancement of the APEnet+ hardware through the adoption of new generation 28 nm FPGAs allowing the implementation of PCIe Gen3 host interface and the addition of new fault tolerance-oriented capabilities.

  5. Knowledge Based 3d Building Model Recognition Using Convolutional Neural Networks from LIDAR and Aerial Imageries

    NASA Astrophysics Data System (ADS)

    Alidoost, F.; Arefi, H.

    2016-06-01

    In recent years, with the development of the high resolution data acquisition technologies, many different approaches and algorithms have been presented to extract the accurate and timely updated 3D models of buildings as a key element of city structures for numerous applications in urban mapping. In this paper, a novel and model-based approach is proposed for automatic recognition of buildings' roof models such as flat, gable, hip, and pyramid hip roof models based on deep structures for hierarchical learning of features that are extracted from both LiDAR and aerial ortho-photos. The main steps of this approach include building segmentation, feature extraction and learning, and finally building roof labeling in a supervised pre-trained Convolutional Neural Network (CNN) framework to have an automatic recognition system for various types of buildings over an urban area. In this framework, the height information provides invariant geometric features for convolutional neural network to localize the boundary of each individual roofs. CNN is a kind of feed-forward neural network with the multilayer perceptron concept which consists of a number of convolutional and subsampling layers in an adaptable structure and it is widely used in pattern recognition and object detection application. Since the training dataset is a small library of labeled models for different shapes of roofs, the computation time of learning can be decreased significantly using the pre-trained models. The experimental results highlight the effectiveness of the deep learning approach to detect and extract the pattern of buildings' roofs automatically considering the complementary nature of height and RGB information.

  6. Fabrication of dual-pore scaffolds using SLUP (salt leaching using powder) and WNM (wire-network molding) techniques.

    PubMed

    Cho, Yong Sang; Hong, Myoung Wha; Kim, So-Youn; Lee, Seung-Jae; Lee, Jun Hee; Kim, Young Yul; Cho, Young-Sam

    2014-12-01

    In this study, a novel technique was proposed to fabricate dual-pore scaffolds combining both SLUP (salt leaching using powder) and WNM (wire-network molding) techniques. This technique has several advantages: solvent-free, no limit on the use of thermoplastic polymers as a raw material, and easiness of fabricating scaffolds with dual-scale pores that are interconnected randomized small pores. To fabricate dual-pore scaffolds, PCL and NaCl powders were mixed at a certain ratio. Subsequently, needles were inserted into a designed mold, and the mixture was filled into the mold thereafter. Subsequently, after the mold was pressurized, the mold was heated to melt the PCL powders. The PCL/NaCl structure and needles were separated from the mold. The structure was sonicated to leach-out the NaCl particles and was dried. Consequently, the remaining PCL structure became the dual-pore scaffold. To compare the characteristics of dual-pore scaffolds, control scaffolds, which are 3D plotter and SLUP scaffolds were fabricated. PMID:25491863

  7. Three dimensional analysis of the pore space in fine-grained Boom Clay, using BIB-SEM (broad-ion beam scanning electron microscopy), combined with FIB (focused ion-beam) serial cross-sectioning, pore network modeling and Wood's metal injection

    NASA Astrophysics Data System (ADS)

    Hemes, Susanne; Klaver, Jop; Desbois, Guillaume; Urai, Janos

    2014-05-01

    The Boom Clay is, besides the Ypresian clays, one of the potential host rock materials for radioactive waste disposal in Belgium (Gens et al., 2003; Van Marcke & Laenen, 2005; Verhoef et al., 2011). To access parameters, which are relevant for the diffusion controlled transport of radionuclides in the material, such as porosity, pore connectivity and permeability, it is crucial to characterize the pore space at high resolution (nm-scale) and in 3D. Focused-ion-beam (FIB) serial cross-sectioning in combination with high resolution scanning electron microscopy (SEM), pore network modeling, Wood's metal injection and broad-ion-beam (BIB) milling, constitute a superior set of methods to characterize the 3D pore space in fine-grained, clayey materials, down to the nm-scale resolution. In the present study, we identified characteristic 3D pore space morphologies, determined the 3D volume porosity of the material and applied pore network extraction modeling (Dong and Blunt, 2009), to access the connectivity of the pore space and to discriminate between pore bodies and pore throats. Moreover, we used Wood's metal injection (WMI) in combination with BIB-SEM imaging to assess the pore connectivity at a larger scale and even higher resolution. The FIB-SEM results show a highly (~ 90 %) interconnected pore space in Boom Clay, down to the resolution of ~ 3E+03 nm³ (voxel-size), with a total volume porosity of ~ 20 %. Pore morphologies of large (> 5E+08 nm³), highly interconnected pores are complex, with high surface area to volume ratios (shape factors G ~ 0.01), whereas small (< 1E+06 nm³), often isolated pores are much more compact and show higher shape factors (G) up to 0.03. WMI in combination with BIB-SEM, down to a resolution of ~ 50 nm² pixel-size, indicates an interconnected porosity fraction of ~ 80 %, of a total measured 2D porosity of ~ 20 %. Determining and distinguishing between pore bodies and pore throats enables us to compare 3D FIB-SEM pore

  8. Characterization of New PEEK/HA Composites with 3D HA Network Fabricated by Extrusion Freeforming.

    PubMed

    Vaezi, Mohammad; Black, Cameron; Gibbs, David M R; Oreffo, Richard O C; Brady, Mark; Moshrefi-Torbati, Mohamed; Yang, Shoufeng

    2016-01-01

    Addition of bioactive materials such as calcium phosphates or Bioglass, and incorporation of porosity into polyetheretherketone (PEEK) has been identified as an effective approach to improve bone-implant interfaces and osseointegration of PEEK-based devices. In this paper, a novel production technique based on the extrusion freeforming method is proposed that yields a bioactive PEEK/hydroxyapatite (PEEK/HA) composite with a unique configuration in which the bioactive phase (i.e., HA) distribution is computer-controlled within a PEEK matrix. The 100% interconnectivity of the HA network in the biocomposite confers an advantage over alternative forms of other microstructural configurations. Moreover, the technique can be employed to produce porous PEEK structures with controlled pore size and distribution, facilitating greater cellular infiltration and biological integration of PEEK composites within patient tissue. The results of unconfined, uniaxial compressive tests on these new PEEK/HA biocomposites with 40% HA under both static and cyclic mode were promising, showing the composites possess yield and compressive strength within the range of human cortical bone suitable for load bearing applications. In addition, preliminary evidence supporting initial biological safety of the new technique developed is demonstrated in this paper. Sufficient cell attachment, sustained viability in contact with the sample over a seven-day period, evidence of cell bridging and matrix deposition all confirmed excellent biocompatibility. PMID:27240326

  9. The impact of fluid topology on residual saturations - A pore-network model study

    NASA Astrophysics Data System (ADS)

    Doster, F.; Kallel, W.; van Dijke, R.

    2014-12-01

    In two-phase flow in porous media only fractions of the resident fluid are mobilised during a displacement process and, in general, a significant amount of the resident fluid remains permanently trapped. Depending on the application, entrapment is desirable (geological carbon storage), or it should be obviated (enhanced oil recovery, contaminant remediation). Despite its utmost importance for these applications, predictions of trapped fluid saturations for macroscopic systems, in particular under changing displacement conditions, remain challenging. The models that aim to represent trapping phenomena are typically empirical and require tracking of the history of the state variables. This exacerbates the experimental verification and the design of sophisticated displacement technologies that enhance or impede trapping. Recently, experiments [1] have suggested that a macroscopic normalized Euler number, quantifying the topology of fluid distributions, could serve as a parameter to predict residual saturations based on state variables. In these experiments the entrapment of fluids was visualised through 3D micro CT imaging. However, the experiments are notoriously time consuming and therefore only allow for a sparse sampling of the parameter space. Pore-network models represent porous media through an equivalent network structure of pores and throats. Under quasi-static capillary dominated conditions displacement processes can be modeled through simple invasion percolation rules. Hence, in contrast to experiments, pore-network models are fast and therefore allow full sampling of the parameter space. Here, we use pore-network modeling [2] to critically investigate the knowledge gained through observing and tracking the normalized Euler number. More specifically, we identify conditions under which (a) systems with the same saturations but different normalized Euler numbers lead to different residual saturations and (b) systems with the same saturations and the same

  10. Superior Sodium Storage in 3D Interconnected Nitrogen and Oxygen Dual-Doped Carbon Network.

    PubMed

    Wang, Min; Yang, Zhenzhong; Li, Weihan; Gu, Lin; Yu, Yan

    2016-05-01

    Carbonaceous materials have attracted immense interest as anode materials for Na-ion batteries (NIBs) because of their good chemical, thermal stabilities, as well as high Na-storage capacity. However, the carbonaceous materials as anodes for NIBs still suffer from the lower rate capability and poor cycle life. An N,O-dual doped carbon (denoted as NOC) network is designed and synthesized, which is greatly favorable for sodium storage. It exhibits high specific capacity and ultralong cycling stability, delivering a capacity of 545 mAh g(-1) at 100 mA g(-1) after 100 cycles and retaining a capacity of 240 mAh g(-1) at 2 A g(-1) after 2000 cycles. The NOC composite with 3D well-defined porosity and N,O-dual doped induces active sites, contributing to the enhanced sodium storage. In addition, the NOC is synthesized through a facile solution process, which can be easily extended to the preparation of many other N,O-dual doped carbonaceous materials for wide applications in catalysis, energy storage, and solar cells. PMID:27028729

  11. Micro- and nano-X-ray computed-tomography: A step forward in the characterization of the pore network of a leached cement paste

    SciTech Connect

    Bossa, Nathan; Chaurand, Perrine; Vicente, Jérôme; Borschneck, Daniel; Levard, Clément; Aguerre-Chariol, Olivier; Rose, Jérôme

    2015-01-15

    Pore structure of leached cement pastes (w/c = 0.5) was studied for the first time from micro-scale down to the nano-scale by combining micro- and nano-X-ray computed tomography (micro- and nano-CT). This allowed assessing the 3D heterogeneity of the pore network along the cement profile (from the core to the altered layer) of almost the entire range of cement pore size, i.e. from capillary to gel pores. We successfully quantified an increase of porosity in the altered layer at both resolutions. Porosity is increasing from 1.8 to 6.1% and from 18 to 58% at the micro-(voxel = 1.81 μm) and nano-scale (voxel = 63.5 nm) respectively. The combination of both CT allowed to circumvent weaknesses inherent of both investigation scales. In addition the connectivity and the channel size of the pore network were also evaluated to obtain a complete 3D pore network characterization at both scales.

  12. Spatio-temporal interpolation of soil moisture in 3D+T using automated sensor network data

    NASA Astrophysics Data System (ADS)

    Gasch, C.; Hengl, T.; Magney, T. S.; Brown, D. J.; Gräler, B.

    2014-12-01

    Soil sensor networks provide frequent in situ measurements of dynamic soil properties at fixed locations, producing data in 2- or 3-dimensions and through time (2D+T and 3D+T). Spatio-temporal interpolation of 3D+T point data produces continuous estimates that can then be used for prediction at unsampled times and locations, as input for process models, and can simply aid in visualization of properties through space and time. Regression-kriging with 3D and 2D+T data has successfully been implemented, but currently the field of geostatistics lacks an analytical framework for modeling 3D+T data. Our objective is to develop robust 3D+T models for mapping dynamic soil data that has been collected with high spatial and temporal resolution. For this analysis, we use data collected from a sensor network installed on the R.J. Cook Agronomy Farm (CAF), a 37-ha Long-Term Agro-Ecosystem Research (LTAR) site in Pullman, WA. For five years, the sensors have collected hourly measurements of soil volumetric water content at 42 locations and five depths. The CAF dataset also includes a digital elevation model and derivatives, a soil unit description map, crop rotations, electromagnetic induction surveys, daily meteorological data, and seasonal satellite imagery. The soil-water sensor data, combined with the spatial and temporal covariates, provide an ideal dataset for developing 3D+T models. The presentation will include preliminary results and address main implementation strategies.

  13. Scattering and coupling effects of electromagnetic waves in 3D networks of spheres

    NASA Astrophysics Data System (ADS)

    Defos Du Rau, M.; Pessan, F.; Ruffie, G.; Vignéras-Lefebvre, V.; Parneix, J. P.

    1998-01-01

    In this paper, the problem of electromagnetic scattering from a 3D system of spheres is considered and an iterative solution that accounts for multiple scattering is proposed. The Mie formalism used for a single sphere is extended to account for multiple scattered fields between several particles. The translational addition theorems for spherical wave functions are used to express the electromagnetic field scattered by a sphere S_i in terms of an incident field for a sphere S_k in a spherical coordinates system attached to the sphere S_k. In this work, the numerical convergence of the method is discussed and associated computational times are given. Numerical computations including Radar Cross Section (RCS) and radiation patterns for various 3D configurations are presented. Some of them are compared with free-space measurements made in the 8 to 100 GHz frequency band using vectorial network analyzers. 11.55.-m S-matrix theory; analytic structure of amplitudes Cet article étudie la diffusion des ondes électromagnétiques par des réseaux tridimensionnels de sphères et propose une méthode itérative pour prendre en compte les effets de multidiffusion. Le formalisme de Mie utilisé dans le cas d'une sphère est étendu pour calculer les champs "multidiffusés" entre plusieurs particules. Les théorèmes d'addition et de translation des fonctions d'onde sphériques sont utilisés pour exprimer le champ diffusé par une sphère S_i comme étant incident sur une sphère S_k, dans un système de coordonnées sphériques lié au centre de S_k. La convergence numérique de la méthode est discutée et des temps de calcul sont donnés. Des résultats numériques tels que des Surfaces Équivalentes Radar (SER) et des diagrammes de rayonnement pour différentes configurations tridimensionnelles sont montrés. Certains d'entre eux sont comparés à des mesures en espace libre faites à l'aide d'analyseurs de réseaux vectoriels dans la bande de fréquence 8{-}100 GHz.

  14. A level set method for solid-liquid interface tracking in texturally equilibrated pore networks

    NASA Astrophysics Data System (ADS)

    Ghanbarzadeh, Soheil; Hesse, Marc; Prodanovic, Masa

    2015-04-01

    The properties of some porous media are determined by their evolution towards textural equilibrium. Melt drainage from temperate glacier ice and the accumulation of hydrocarbons beneath rock salt are two examples in natural systems. In these materials, pore geometry evolves to minimize the solid-liquid interfacial energy while maintaining dihedral angle, θ, at solid-liquid contact lines. In this work we present the first computations of 3-D texturally equilibrated pore networks using a novel level set method. Interfacial energy minimization is achieved by evolving interface under surface diffusion to constant mean curvature surface. The porosity and dihedral angle constraints are added to the formulation using virtual velocity terms. A domain decomposition scheme is devised to restrict the computational domain and the coupling between the interfaces is achieved on the original computational domain. For the last 30 years, explicit representation of the interfaces limited the computations to highly idealized geometries. The presented model overcomes these limitations and opens the door to the exploration of the physics of these materials in realistic systems. For example, our results show that the fully wetted grain boundaries exist even for θ>0 which reconciles the theory with experimental observations. This work is sponsored by the Statoil Fellows Program at The University of Texas.

  15. Changes in the pore network structure of Hanford sediment after reaction with caustic tank wastes.

    PubMed

    Crandell, L E; Peters, C A; Um, W; Jones, K W; Lindquist, W B

    2012-04-01

    At the former nuclear weapon production site in Hanford, WA, caustic radioactive tank waste leaks into subsurface sediments and causes dissolution of quartz and aluminosilicate minerals, and precipitation of sodalite and cancrinite. This work examines changes in pore structure due to these reactions in a previously-conducted column experiment. The column was sectioned and 2D images of the pore space were generated using backscattered electron microscopy and energy dispersive X-ray spectroscopy. A pre-precipitation scenario was created by digitally removing mineral matter identified as secondary precipitates. Porosity, determined by segmenting the images to distinguish pore space from mineral matter, was up to 0.11 less after reaction. Erosion-dilation analysis was used to compute pore and throat size distributions. Images with precipitation had more small and fewer large pores. Precipitation decreased throat sizes and the abundance of large throats. These findings agree with previous findings based on 3D X-ray CMT imaging, observing decreased porosity, clogging of small throats, and little change in large throats. However, 2D imaging found an increase in small pores, mainly in intragranular regions or below the resolution of the 3D images. Also, an increase in large pores observed via 3D imaging was not observed in the 2D analysis. Changes in flow conducting throats that are the key permeability-controlling features were observed in both methods. PMID:22360994

  16. Changes in the pore network structure of Hanford sediment after reaction with caustic tank wastes

    SciTech Connect

    Crandell, L. E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

    2012-04-01

    At the former nuclear weapon production site in Hanford, WA, caustic radioactive tank waste leaks into subsurface sediments and causes dissolution of quartz and aluminosilicate minerals, and precipitation of sodalite and cancrinite. This work examines changes in pore structure due to these reactions in a previously-conducted column experiment. The column was sectioned and 2D images of the pore space were generated using backscattered electron microscopy and energy dispersive X-ray spectroscopy. A pre-precipitation scenario was created by digitally removing mineral matter identified as secondary precipitates. Porosity, determined by segmenting the images to distinguish pore space from mineral matter, was up to 0.11 less after reaction. Erosion-dilation analysis was used to compute pore and throat size distributions. Images with precipitation had more small and fewer large pores. Precipitation decreased throat sizes and the abundance of large throats. These findings agree with previous findings based on 3D X-ray CMT imaging, observing decreased porosity, clogging of small throats, and little change in large throats. However, 2D imaging found an increase in small pores, mainly in intragranular regions or below the resolution of the 3D images. Also, an increase in large pores observed via 3D imaging was not observed in the 2D analysis. Changes in flow conducting throats that are the key permeability-controlling features were observed in both methods.

  17. A Facile Route to Bimetal and Nitrogen-Codoped 3D Porous Graphitic Carbon Networks for Efficient Oxygen Reduction.

    PubMed

    Zhang, Zhengping; Dou, Meiling; Liu, Haijing; Dai, Liming; Wang, Feng

    2016-08-01

    Bimetal nitrogen-doped carbon with both Fe and Co, derived from the pyrolysis carbon of iron and cobalt phthalocyanine-based conjugated polymer networks, possesses a few-layer graphene-like texture with hierarchical porosity in meso/micro multimodal pore size distribution. The novel electrocatalyst exhibits Pt-like catalytic activity and much higher catalytic durability for oxygen reduction. PMID:27389707

  18. Modeling the controllable pH-responsive swelling and pore size of networked alginate based biomaterials.

    PubMed

    Chan, Ariel W; Neufeld, Ronald J

    2009-10-01

    Semisynthetic network alginate polymer (SNAP), synthesized by acetalization of linear alginate with di-aldehyde, is a pH-responsive tetrafunctionally linked 3D gel network, and has potential application in oral delivery of protein therapeutics and active biologicals, and as tissue bioscaffold for regenerative medicine. A constitutive polyelectrolyte gel model based on non-Gaussian polymer elasticity, Flory-Huggins liquid lattice theory, and non-ideal Donnan membrane equilibria was derived, to describe SNAP gel swelling in dilute and ionic solutions containing uni-univalent, uni-bivalent, bi-univalent or bi-bi-valent electrolyte solutions. Flory-Huggins interaction parameters as a function of ionic strength and characteristic ratio of alginates of various molecular weights were determined experimentally to numerically predict SNAP hydrogel swelling. SNAP hydrogel swells pronouncedly to 1000 times in dilute solution, compared to its compact polymer volume, while behaving as a neutral polymer with limited swelling in high ionic strength or low pH solutions. The derived model accurately describes the pH-responsive swelling of SNAP hydrogel in acid and alkaline solutions of wide range of ionic strength. The pore sizes of the synthesized SNAP hydrogels of various crosslink densities were estimated from the derived model to be in the range of 30-450 nm which were comparable to that measured by thermoporometry, and diffusion of bovine serum albumin. The derived equilibrium swelling model can characterize hydrogel structure such as molecular weight between crosslinks and crosslinking density, or can be used as predictive model for swelling, pore size and mechanical properties if gel structural information is known, and can potentially be applied to other point-link network polyelectrolytes such as hyaluronic acid gel. PMID:19660810

  19. Application of artificial neural network in 3D imaging with lanthanum bromide calorimeter

    NASA Astrophysics Data System (ADS)

    Gostojic, A.; Tatischeff, V.; Kiener, J.; Hamadache, C.; Karkour, N.; Linget, D.; Grave, X.; Gibelin, L.; Travers, B.; Blin, S.; Barrillon, P.

    2015-07-01

    Gamma-ray astronomy in the energy range from 0.1 up to 100 MeV holds many understudied questions connected with e.g. stellar nucleosynthesis, the active Sun, neutron stars and black holes. To access the physics behind, a significant improvement in detection sensitivity is needed compared to previous missions, e.g. CGRO and INTEGRAL. One of the promising concepts for a future gamma-ray mission is an Advanced Compton Telescope. Under the project of creating a prototype of such instrument, we study the perspectives of using a novel inorganic scintillator as a calorimeter part. Modern inorganic crystal or ceramics scintillators are constantly improving on qualities such as energy resolution and radiation hardness, and this makes them a smart choice for a new space-borne telescope. At CSNSM Orsay, we have assembled a detection module from a 5 × 5cm2 area and 1 cm thick, cerium-doped lanthanum (III) bromide (LaBr3:Ce) inorganic scintillator coupled to a 64 channel multi-anode photomultiplier. The readout of the PMT signals is carried out with the ASIC MAROC, used previously for the luminometer of the ATLAS detector (CERN). Characterization, thorough measurements with various radioactive sources, as well as, single photoelectron detection have been done. Furthermore, we made a comparison of measurements with a detailed GEANT4-based simulation which includes tracking of the optical photons. Finally, we have studied the 3D reconstruction of the first interaction point of incident gamma rays, utilizing a neural network algorithm. This spatial position resolution plays a crucial part in the future implementations and, together with the other measured properties, it makes our detector module very interesting for the next generation of space telescopes operating in the MeV range.

  20. Deep MRI brain extraction: A 3D convolutional neural network for skull stripping.

    PubMed

    Kleesiek, Jens; Urban, Gregor; Hubert, Alexander; Schwarz, Daniel; Maier-Hein, Klaus; Bendszus, Martin; Biller, Armin

    2016-04-01

    Brain extraction from magnetic resonance imaging (MRI) is crucial for many neuroimaging workflows. Current methods demonstrate good results on non-enhanced T1-weighted images, but struggle when confronted with other modalities and pathologically altered tissue. In this paper we present a 3D convolutional deep learning architecture to address these shortcomings. In contrast to existing methods, we are not limited to non-enhanced T1w images. When trained appropriately, our approach handles an arbitrary number of modalities including contrast-enhanced scans. Its applicability to MRI data, comprising four channels: non-enhanced and contrast-enhanced T1w, T2w and FLAIR contrasts, is demonstrated on a challenging clinical data set containing brain tumors (N=53), where our approach significantly outperforms six commonly used tools with a mean Dice score of 95.19. Further, the proposed method at least matches state-of-the-art performance as demonstrated on three publicly available data sets: IBSR, LPBA40 and OASIS, totaling N=135 volumes. For the IBSR (96.32) and LPBA40 (96.96) data set the convolutional neuronal network (CNN) obtains the highest average Dice scores, albeit not being significantly different from the second best performing method. For the OASIS data the second best Dice (95.02) results are achieved, with no statistical difference in comparison to the best performing tool. For all data sets the highest average specificity measures are evaluated, whereas the sensitivity displays about average results. Adjusting the cut-off threshold for generating the binary masks from the CNN's probability output can be used to increase the sensitivity of the method. Of course, this comes at the cost of a decreased specificity and has to be decided application specific. Using an optimized GPU implementation predictions can be achieved in less than one minute. The proposed method may prove useful for large-scale studies and clinical trials. PMID:26808333

  1. Evaluation of methods for determining the pore size distribution and pore-network connectivity of porous carbons.

    PubMed

    Cai, Q; Buts, A; Biggs, M J; Seaton, N A

    2007-07-31

    The pore size distribution (PSD) and the pore-network connectivity of a porous material determine its properties in applications such as gas storage, adsorptive separations, and catalysis. Methods for the characterization of the pore structure of porous carbons are widely used, but the relationship between the structural parameters measured and the real structure of the material is not yet clear. We have evaluated two widely used and powerful characterization methods based on adsorption measurements by applying the methods to a model carbon which captures the essential characteristics of real carbons but (unlike a real material) has a structure that is completely known. We used three species (CH4, CF4, and SF6) as adsorptives and analyzed the results using an intersecting capillaries model (ICM) which was modeled using a combination of Monte Carlo simulation and percolation theory to obtain the PSD and the pore-network connectivity. There was broad agreement between the PSDs measured using the ICM and the geometric PSD of the model carbon, as well as some systematic differences which are interpreted in terms of the pore structure of the carbon. The measured PSD and connectivity are shown to be able to predict adsorption in the model carbon, supporting the use of the ICM to characterize real porous carbons. PMID:17602506

  2. Pillared Graphene: A New 3-D Innovative Network Nanostructure Augments Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Georgios, Dimitrakakis K.; Emmanuel, Tylianakis; George, Froudakis E.

    2009-08-01

    Nowadays, people have turned into finding an alternative power source for everyday applications. One of the most promising energy fuels is hydrogen. It can be used as an energy carrier at small portable devices (e.g. laptops and/or cell phones) up to larger, like cars. Hydrogen is considered as the perfect fuel. It can be burnt in combustion engines and the only by-product is water. For hydrogen-powered vehicles a big liming factor is the gas tank and is the reason for not using widely hydrogen in automobile applications. According to United States' Department of Energy (D.O.E.) the target for reversible hydrogen storage in mobile applications is 6% wt. and 45 gr. H2/L and these should be met by 2010. After their synthesis Carbon Nanotubes (CNTs) were considered as ideal candidates for hydrogen storage especially after some initially incorrect but invitingly results. As it was proven later, pristine carbon nanotubes cannot achieve D.O.E.'s targets in ambient conditions of pressure and temperature. Therefore, a way to increase their hydrogen storage capacity should be found. An attempt was done by doping CNTs with alkali metal atoms. Although the results were promising, even that increment was not enough. Consequently, new architectures were suggested as materials that could potentially enhance hydrogen storage. In this work a novel three dimensional (3-D) nanoporous carbon structure called Pillared Graphene (Figure 1) is proposed for augmented hydrogen storage in ambient conditions. Pillared Graphene consists of parallel graphene sheets and CNTs that act like pillars and support the graphene sheets. The entire structure (Figure 1) can be resembled like a building in its early stages of construction, where the floors are represented by graphene sheets and the pillars are the CNTs. As shown in Figure 1, CNTs do not penetrate the structure from top to bottom. Instead, they alternately go up and down, so that on the same plane do not exist two neighboring CNTs with the

  3. Finite element generation of arbitrary 3-D fracture networks for flow analysis in complicated discrete fracture networks

    NASA Astrophysics Data System (ADS)

    Zhang, Qi-Hua

    2015-10-01

    Finite element generation of complicated fracture networks is the core issue and source of technical difficulty in three-dimensional (3-D) discrete fracture network (DFN) flow models. Due to the randomness and uncertainty in the configuration of a DFN, the intersection lines (traces) are arbitrarily distributed in each face (fracture and other surfaces). Hence, subdivision of the fractures is an issue relating to subdivision of two-dimensional (2-D) domains with arbitrarily-distributed constraints. When the DFN configuration is very complicated, the well-known approaches (e.g. Voronoi Delaunay-based methods and advancing-front techniques) cannot operate properly. This paper proposes an algorithm to implement end-to-end connection between traces to subdivide 2-D domains into closed loops. The compositions of the vertices in the common edges between adjacent loops (which may belong to a single fracture or two connected fractures) are thus ensured to be topologically identical. The paper then proposes an approach for triangulating arbitrary loops which does not add any nodes to ensure consistency of the meshes at the common edges. In addition, several techniques relating to tolerance control and improving code robustness are discussed. Finally, the equivalent permeability of the rock mass is calculated for some very complicated DFNs (the DFN may contain 1272 fractures, 633 connected fractures, and 16,270 closed loops). The results are compared with other approaches to demonstrate the veracity and efficiency of the approach proposed in this paper.

  4. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

    PubMed Central

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

    2015-01-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

  5. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

    NASA Astrophysics Data System (ADS)

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

    2015-08-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

  6. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

    PubMed

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

    2015-01-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

  7. Visualization and simulation of bubble growth in pore networks

    SciTech Connect

    Li, Xuehai; Yortsos, Y.C.

    1994-03-01

    Bubble nucleation and bubble growth in porous media is an important problem encountered in processes, such as pressure depletion and boiling. To understand its basic aspects, experiments and numerical simulations in micromodel geometries were undertaken. Experiments of bubble growth by pressure depletion were carried out in 2-D etched-glass micromodels and in Hele-Shaw cells. Nucleation of bubbles and the subsequent growth of gas clusters were visualized. Contrary to the bulk or to Hele-Shaw cells, gas clusters in the micromodel have irregular and ramified shapes and share many of the features of an external invasion process (e.g. of percolation during drainage). A pore network numerical model was developed to simulate the growth of multiple gas clusters under various conditions. The model is based on the solution of the convection-diffusions equation and also accounts for capillary and viscous forces, which play an important role in determining the growth patterns. Numerical simulation resulted in good agreement with the experimental results.

  8. A characterization of the coupled evolution of grain fabric and pore space using complex networks: Pore connectivity and optimized flows in the presence of shear bands

    NASA Astrophysics Data System (ADS)

    Russell, Scott; Walker, David M.; Tordesillas, Antoinette

    2016-03-01

    A framework for the multiscale characterization of the coupled evolution of the solid grain fabric and its associated pore space in dense granular media is developed. In this framework, a pseudo-dual graph transformation of the grain contact network produces a graph of pores which can be readily interpreted as a pore space network. Survivability, a new metric succinctly summarizing the connectivity of the solid grain and pore space networks, measures material robustness. The size distribution and the connectivity of pores can be characterized quantitatively through various network properties. Assortativity characterizes the pore space with respect to the parity of the number of particles enclosing the pore. Multiscale clusters of odd parity versus even parity contact cycles alternate spatially along the shear band: these represent, respectively, local jamming and unjamming regions that continually switch positions in time throughout the failure regime. Optimal paths, established using network shortest paths in favor of large pores, provide clues on preferential paths for interstitial matter transport. In systems with higher rolling resistance at contacts, less tortuous shortest paths thread through larger pores in shear bands. Notably the structural patterns uncovered in the pore space suggest that more robust models of interstitial pore flow through deforming granular systems require a proper consideration of the evolution of in situ shear band and fracture patterns - not just globally, but also inside these localized failure zones.

  9. Polydopamine Inter-Fiber Networks: New Strategy for Producing Rigid, Sticky, 3D Fluffy Electrospun Fibrous Polycaprolactone Sponges.

    PubMed

    Choi, Wuyong; Lee, Slgirim; Kim, Seung-Hyun; Jang, Jae-Hyung

    2016-06-01

    Designing versatile 3D interfaces that can precisely represent a biological environment is a prerequisite for the creation of artificial tissue structures. To this end, electrospun fibrous sponges, precisely mimicking an extracellular matrix and providing highly porous interfaces, have capabilities that can function as versatile physical cues to regenerate various tissues. However, their intrinsic features, such as sheet-like, thin, and weak structures, limit the design of a number of uses in tissue engineering applications. Herein, a highly facile methodology capable of fabricating rigid, sticky, spatially expanded fluffy electrospun fibrous sponges is proposed. A bio-inspired adhesive material, poly(dopamine) (pDA), is employed as a key mediator to provide rigidity and stickiness to the 3D poly(ε-caprolactone) (PCL) fibrous sponges, which are fabricated using a coaxial electrospinning with polystyrene followed by a selective leaching process. The iron ion induced oxidation of dopamine into pDA networks interwoven with PCL fibers results in significant increases in the rigidity of 3D fibrous sponges. Furthermore, the exposure of catecholamine groups on the fiber surfaces promotes the stable attachment of the sponges on wet organ surfaces and triggers the robust immobilization of biomolecules (e.g., proteins and gene vectors), demonstrating their potential for 3D scaffolds as well as drug delivery vehicles. Because fibrous structures are ubiquitous in the human body, these rigid, sticky, 3D fibrous sponges are good candidates for powerful biomaterial systems that functionally mimic a variety of tissue structures. PMID:26855375

  10. Review of pore network modelling of porous media: Experimental characterisations, network constructions and applications to reactive transport

    NASA Astrophysics Data System (ADS)

    Xiong, Qingrong; Baychev, Todor G.; Jivkov, Andrey P.

    2016-09-01

    Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement, non-Darcy flow, reactive transport and thermodynamically consistent oil layers. The realism of such modelling, i.e. the credibility of their predictions, depends to a large extent on the quality of the correspondence between the pore space of a given medium and the pore network constructed as its representation. The main experimental techniques for pore space characterisation, including direct imaging, mercury intrusion porosimetry and gas adsorption, are firstly summarised. A review of the main pore network construction techniques is then presented. Particular focus is given on how such constructions are adapted to the data from experimentally characterised pore systems. Current applications of pore network models are considered, with special emphasis on the effects of adsorption, dissolution and precipitation, as well as biomass growth, on transport coefficients. Pore network models are found to be a valuable tool for understanding and predicting meso-scale phenomena, linking single pore processes, where other techniques are more accurate, and the homogenised continuum porous media, used by engineering community.

  11. Review of pore network modelling of porous media: Experimental characterisations, network constructions and applications to reactive transport.

    PubMed

    Xiong, Qingrong; Baychev, Todor G; Jivkov, Andrey P

    2016-09-01

    Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement, non-Darcy flow, reactive transport and thermodynamically consistent oil layers. The realism of such modelling, i.e. the credibility of their predictions, depends to a large extent on the quality of the correspondence between the pore space of a given medium and the pore network constructed as its representation. The main experimental techniques for pore space characterisation, including direct imaging, mercury intrusion porosimetry and gas adsorption, are firstly summarised. A review of the main pore network construction techniques is then presented. Particular focus is given on how such constructions are adapted to the data from experimentally characterised pore systems. Current applications of pore network models are considered, with special emphasis on the effects of adsorption, dissolution and precipitation, as well as biomass growth, on transport coefficients. Pore network models are found to be a valuable tool for understanding and predicting meso-scale phenomena, linking single pore processes, where other techniques are more accurate, and the homogenised continuum porous media, used by engineering community. PMID:27442725

  12. Effect of Ductile Agents on the Dynamic Behavior of SiC3D Network Composites

    NASA Astrophysics Data System (ADS)

    Zhu, Jingbo; Wang, Yangwei; Wang, Fuchi; Fan, Qunbo

    2016-07-01

    Co-continuous SiC ceramic composites using pure aluminum, epoxy, and polyurethane (PU) as ductile agents were developed. The dynamic mechanical behavior and failure mechanisms were investigated experimentally using the split Hopkinson pressure bar (SHPB) method and computationally by finite element (FE) simulations. The results show that the SiC3D/Al composite has the best overall performance in comparison with SiC3D/epoxy and SiC3D/PU composites. FE simulations are generally consistent with experimental data. These simulations provide valuable help in predicting mechanical strength and in interpreting the experimental results and failure mechanisms. They may be combined with micrographs for fracture characterizations of the composites. We found that interactions between the SiC phase and ductile agents under dynamic compression in the SHPB method are complex, and that interfacial condition is an important parameter that determines the mechanical response of SiC3D composites with a characteristic interlocking structure during dynamic compression. However, the effect of the mechanical properties of ductile agents on dynamic behavior of the composites is a second consideration in the production of the composites.

  13. Fabrication of 3D high aspect ratio PDMS microfluidic networks with a hybrid stamp.

    PubMed

    Kung, Yu-Chun; Huang, Kuo-Wei; Fan, Yu-Jui; Chiou, Pei-Yu

    2015-04-21

    We report a novel methodology for fabricating large-area, multilayer, thin-film, high aspect ratio, 3D microfluidic structures with through-layer vias and open channels that can be bonded between hard substrates. It is realized by utilizing a hybrid stamp with a thin plastic sheet embedded underneath a PDMS surface. This hybrid stamp solves an important edge protrusion issue during PDMS molding while maintaining necessary stamp elasticity to ensure the removal of PDMS residues at through-layer regions. Removing edge protrusion is a significant progress toward fabricating 3D structures since high aspect ratio PDMS structures with flat interfaces can be realized to facilitate multilayer stacking and bonding to hard substrates. Our method also allows for the fabrication of 3D deformable channels, which can lead to profound applications in electrokinetics, optofluidics, inertial microfluidics, and other fields where the shape of the channel cross section plays a key role in device physics. To demonstrate, as an example, we have fabricated a microfluidic channel by sandwiching two 20 μm wide, 80 μm tall PDMS membranes between two featureless ITO glass substrates. By applying electrical bias to the two ITO substrates and pressure to deform the thin membrane sidewalls, strong electric field enhancement can be generated in the center of a channel to enable 3D sheathless dielectrophoretic focusing of biological objects including mammalian cells and bacteria at a flow speed up to 14 cm s(-1). PMID:25710255

  14. Recovering 3D Shape with Absolute Size from Endoscope Images Using RBF Neural Network

    PubMed Central

    Tsuda, Seiya; Iwahori, Yuji; Bhuyan, M. K.; Woodham, Robert J.; Kasugai, Kunio

    2015-01-01

    Medical diagnosis judges the status of polyp from the size and the 3D shape of the polyp from its medical endoscope image. However the medical doctor judges the status empirically from the endoscope image and more accurate 3D shape recovery from its 2D image has been demanded to support this judgment. As a method to recover 3D shape with high speed, VBW (Vogel-Breuß-Weickert) model is proposed to recover 3D shape under the condition of point light source illumination and perspective projection. However, VBW model recovers the relative shape but there is a problem that the shape cannot be recovered with the exact size. Here, shape modification is introduced to recover the exact shape with modification from that with VBW model. RBF-NN is introduced for the mapping between input and output. Input is given as the output of gradient parameters of VBW model for the generated sphere. Output is given as the true gradient parameters of true values of the generated sphere. Learning mapping with NN can modify the gradient and the depth can be recovered according to the modified gradient parameters. Performance of the proposed approach is confirmed via computer simulation and real experiment. PMID:25949235

  15. Functional metabolic interactions of human neuron-astrocyte 3D in vitro networks.

    PubMed

    Simão, Daniel; Terrasso, Ana P; Teixeira, Ana P; Brito, Catarina; Sonnewald, Ursula; Alves, Paula M

    2016-01-01

    The generation of human neural tissue-like 3D structures holds great promise for disease modeling, drug discovery and regenerative medicine strategies. Promoting the establishment of complex cell-cell interactions, 3D culture systems enable the development of human cell-based models with increased physiological relevance, over monolayer cultures. Here, we demonstrate the establishment of neuronal and astrocytic metabolic signatures and shuttles in a human 3D neural cell model, namely the glutamine-glutamate-GABA shuttle. This was indicated by labeling of neuronal GABA following incubation with the glia-specific substrate [2-(13)C]acetate, which decreased by methionine sulfoximine-induced inhibition of the glial enzyme glutamine synthetase. Cell metabolic specialization was further demonstrated by higher pyruvate carboxylase-derived labeling in glutamine than in glutamate, indicating its activity in astrocytes and not in neurons. Exposure to the neurotoxin acrylamide resulted in intracellular accumulation of glutamate and decreased GABA synthesis. These results suggest an acrylamide-induced impairment of neuronal synaptic vesicle trafficking and imbalanced glutamine-glutamate-GABA cycle, due to loss of cell-cell contacts at synaptic sites. This work demonstrates, for the first time to our knowledge, that neural differentiation of human cells in a 3D setting recapitulates neuronal-astrocytic metabolic interactions, highlighting the relevance of these models for toxicology and better understanding the crosstalk between human neural cells. PMID:27619889

  16. Pore-scale simulation of calcium carbonate precipitation and dissolution under highly supersaturated conditions in a microfludic pore network

    NASA Astrophysics Data System (ADS)

    Yoon, H.; Dewers, T. A.; Valocchi, A. J.; Werth, C. J.

    2011-12-01

    Dissolved CO2 during geological CO2 storage may react with minerals in fractured rocks or confined aquifers and cause mineral precipitation. The overall rate of reaction can be affected by coupled processes among hydrodynamics, transport, and reactions at pore-scale. Pore-scale models of coupled fluid flow, reactive transport, and CaCO3 precipitation and dissolution are applied to account for transient experimental results of CaCO3 precipitation and dissolution under highly supersaturated conditions in a microfluidic pore network (i.e., micromodel). Pore-scale experiments in the micromodel are used as a basis for understanding coupled physics of systems perturbed by geological CO2 injection. In the micromodel, precipitation is induced by transverse mixing along the centerline in pore bodies. Overall, the pore-scale model qualitatively captured the governing physics of reactions such as precipitate morphology, precipitation rate, and maximum precipitation area in first few pore spaces. In particular, we found that proper estimation of the effective diffusion coefficient and the reactive surface area is necessary to adequately simulate precipitation and dissolution rates. As the model domain increases, the effect of flow patterns affected by precipitation on the overall reaction rate also increases. The model is also applied to account for the effect of different reaction rate laws on mineral precipitation and dissolution at pore-scale. Reaction rate laws tested include the linear rate law, nonlinear power law, and newly-developed rate law based on in-situ measurements at nano scale in the literature. Progress on novel methods for upscaling pore-scale models for reactive transport are discussed, and are being applied to mineral precipitation patterns observed in natural analogues. H.Y. and T. D. were supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of

  17. A Pore-Network Model of In-Situ Combustion in Porous Media

    SciTech Connect

    Lu, Chuan; Yortsos, Y.C.

    2001-01-29

    This report the use of dual pore networks (pores and solid sites) for modeling the effect of the microstructure on combustion processes in porous media is considered. The model accounts for flow and transport of the gas phase in the porespace, where convection predominates, and for heat transfer by conduction in the solid phase. Gas phase flow in the pore and throats is governed by Darcy's law.

  18. From 1D chain to 3D network: A theoretical study on TiO2 low dimensional structures

    NASA Astrophysics Data System (ADS)

    Guo, Ling-ju; Zeng, Zhi; He, Tao

    2015-06-01

    We have performed a systematic study on a series of low dimensional TiO2 nanostructures under density functional theory methods. The geometries, stabilities, growth mechanism, and electronic structures of 1D chain, 2D ring, 2D ring array, and 3D network of TiO2 nanostructures are analyzed. Based on the Ti2O4 building unit, a series of 1D TiO2 nano chains and rings can be built. Furthermore, 2D ring array and 3D network nanostructures can be constructed from 1D chains and rings. Among non-periodic TiO2 chain and ring structures, one series of ring structures is found to be more stable. The geometry model of the 2D ring arrays and 3D network structures in this work has provided a theoretical understanding on the structure information in experiments. Based on these semiconductive low dimensional structures, moreover, it can help to understand and design new hierarchical TiO2 nanostructure in the future.

  19. From 1D chain to 3D network: A theoretical study on TiO{sub 2} low dimensional structures

    SciTech Connect

    Guo, Ling-ju; He, Tao; Zeng, Zhi

    2015-06-14

    We have performed a systematic study on a series of low dimensional TiO{sub 2} nanostructures under density functional theory methods. The geometries, stabilities, growth mechanism, and electronic structures of 1D chain, 2D ring, 2D ring array, and 3D network of TiO{sub 2} nanostructures are analyzed. Based on the Ti{sub 2}O{sub 4} building unit, a series of 1D TiO{sub 2} nano chains and rings can be built. Furthermore, 2D ring array and 3D network nanostructures can be constructed from 1D chains and rings. Among non-periodic TiO{sub 2} chain and ring structures, one series of ring structures is found to be more stable. The geometry model of the 2D ring arrays and 3D network structures in this work has provided a theoretical understanding on the structure information in experiments. Based on these semiconductive low dimensional structures, moreover, it can help to understand and design new hierarchical TiO{sub 2} nanostructure in the future.

  20. Role of 3D force networks in linking grain scale to macroscale processes in sheared granular debris

    NASA Astrophysics Data System (ADS)

    Mair, K.; Jettestuen, E.; Abe, S.

    2013-12-01

    Active faults, landslides and subglacial tills contain accumulations of granular debris that evolve during sliding. The macroscopic motion in these environments is at least to some extent determined by processes operating in this sheared granular material. A valid question is how the local behavior at the individual granular contacts actually sums up to influence macroscopic sliding. Laboratory experiments and numerical modeling can potentially help elucidate this. Observations of jamming (stick) and unjamming (flow) as well as concentrated shear bands on the scale of 5-10 grains suggest that a simple continuum description may be insufficient to capture important elements of the behavior. We therefore seek a measure of the organization of the granular fabric and the 3D structure of the load bearing skeleton that effectively demonstrates how the individual grain interactions are manifested in the macroscopic sliding behavior we observe. Contact force networks are an expression of this. Here we investigate the structure and variability of the most connected system spanning force networks produced in 3D discrete element models of granular layers under shear. We use percolation measures to identify, characterize, compare and track the evolution of these strongly connected contact force networks. We show that specific topological measures used in describing the networks, such as number of contacts and coordination number, are sensitive to grain size distribution (and likely the grain shape) of the material as well as loading conditions. Hence, faults of different maturity would be expected to accommodate shear in different ways. Distinct changes in the topological characteristics i.e. the geometry of strong force networks with accumulated strain are directly correlated to fluctuations in macroscopic shearing resistance. This suggests that 3D force networks play an important bridging role between individual grain scale processes and macroscopic sliding behavior.

  1. Construction of Large-Volume Tissue Mimics with 3D Functional Vascular Networks.

    PubMed

    Kang, Tae-Yun; Hong, Jung Min; Jung, Jin Woo; Kang, Hyun-Wook; Cho, Dong-Woo

    2016-01-01

    We used indirect stereolithography (SL) to form inner-layered fluidic networks in a porous scaffold by introducing a hydrogel barrier on the luminal surface, then seeded the networks separately with human umbilical vein endothelial cells and human lung fibroblasts to form a tissue mimic containing vascular networks. The artificial vascular networks provided channels for oxygen transport, thus reducing the hypoxic volume and preventing cell death. The endothelium of the vascular networks significantly retarded the occlusion of channels during whole-blood circulation. The tissue mimics have the potential to be used as an in vitro platform to examine the physiologic and pathologic phenomena through vascular architecture. PMID:27228079

  2. Construction of Large-Volume Tissue Mimics with 3D Functional Vascular Networks

    PubMed Central

    Kang, Tae-Yun; Hong, Jung Min; Jung, Jin Woo; Kang, Hyun-Wook; Cho, Dong-Woo

    2016-01-01

    We used indirect stereolithography (SL) to form inner-layered fluidic networks in a porous scaffold by introducing a hydrogel barrier on the luminal surface, then seeded the networks separately with human umbilical vein endothelial cells and human lung fibroblasts to form a tissue mimic containing vascular networks. The artificial vascular networks provided channels for oxygen transport, thus reducing the hypoxic volume and preventing cell death. The endothelium of the vascular networks significantly retarded the occlusion of channels during whole-blood circulation. The tissue mimics have the potential to be used as an in vitro platform to examine the physiologic and pathologic phenomena through vascular architecture. PMID:27228079

  3. 3D structure of macropore networks within natural and de-embarked estuary saltmarsh sediments: towards an improved understanding of network structural control over hydrologic function

    NASA Astrophysics Data System (ADS)

    Carr, Simon; Spencer, Kate; James, Tempest; Lucy, Diggens

    2015-04-01

    Saltmarshes are globally important environments which, though occupying < 4% of the Earth's surface, provide a range of ecosystem services. Yet, they are threatened by sea level rise, human population growth, urbanization and pollution resulting in degradation. To compensate for this habitat loss many coastal restoration projects have been implemented over the last few decades, largely driven by legislative requirements for improved biodiversity e.g. the EU Habitats Directive and Birds Directive. However, there is growing evidence that restored saltmarshes, recreated through the return to tidal inundation of previously drained and defended low-lying coastal land, do not have the same species composition even after 100 years and while environmental enhancement has been achieved, there may be consequences for ecosystem functioning This study presents the findings of a comparative analysis of detailed sediment structure and hydrological functioning of equivalent natural and de-embanked saltmarsh sediments at Orplands Farm, Essex, UK. 3D x-ray CT scanning of triplicate undisturbed sediment cores recovered in 2013 have been used to derive detailed volumetric reconstructions of macropore structure and networks, and to infer differences in bulk microporosity between natural and de-embanked saltmarshes. These volumes have been further visualised for qualitative analysis of the main sediment components, and extraction of key macropore space parameters for quantified analysis including total porosity and connectivity, as well as structure, organisation and efficiency (tortuosity) of macropore networks. Although total porosity was significantly greater within the de-embanked saltmarsh sediments, pore networks in these samples were less organised and more tortuous, and were also inferred to have significantly lower micro-porosity than those of the natural saltmarsh. These datasets are applied to explain significant differences in the hydraulic behaviour and functioning

  4. Aligning 3D nanofibrous networks from self-assembled phenylalanine nanofibers†

    PubMed Central

    Wang, Xianfeng; Chen, Yi Charlie

    2015-01-01

    Self-assembled synthetic materials are typically disordered, and controlling the alignment of such materials at the nanometer scale may be important for a variety of biological applications. In this study, we have applied directional freeze-drying, for the first time, to develop well aligned three dimensional (3D) nanofibrous materials using amino acid like L-phenylalanine (Phe). 3D free-standing Phe nanofibrous monoliths have been successfully prepared using directional freeze-drying, and have presented a unique hierarchical structure with well-aligned nanofibers at the nanometer scale and an ordered compartmental architecture at the micrometer scale. We have found that the physical properties (e.g. nanofiber density and alignment) of the nanofibrous materials could be tuned by controlling the concentration and pH of the Phe solution and the freezing temperature. Moreover, the same strategy (i.e. directional freeze-drying) has been successfully applied to assemble peptide nanofibrous materials using a dipeptide (i.e. diphenylalanine), and to assemble Phe-based nanofibrous composites using polyethylenimine and poly(vinyl alcohol). The tunability of the nanofibrous structures together with the biocompatibility of Phe may make these 3D nanofibrous materials suitable for a variety of applications, including biosensor templates, tissue scaffolds, filtration membranes, and absorbents. The strategy reported here is likely applicable to create aligned nanofibrous structures using other amino acids, peptides, and polymers. PMID:25621167

  5. VISUALIZATION AND SIMULATION OF NON-AQUEOUS PHASE LIQUIDS SOLUBILIZATION IN PORE NETWORKS

    EPA Science Inventory

    The design of in-situ remediation of contaminated soils is mostly based on a description at the macroscopic scale using a averaged quantities. These cannot address issues at the pore and pore network scales. In this paper, visualization experiments and numerical simulations in ...

  6. Bi-Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

    NASA Astrophysics Data System (ADS)

    Shi, Fa-Nian; Rosa Silva, Ana; Bian, Liang

    2015-05-01

    A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn-Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi2O(1,3,5-BTC)2]n (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi4O2(COO)12 clusters which are further connected to Mn(COO)6 fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of {413.62}{413.68}{416.65}{418.610}{422.614}{43} corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones.

  7. Osteochondral Regeneration: Tuning Cell Differentiation into a 3D Scaffold Presenting a Pore Shape Gradient for Osteochondral Regeneration (Adv. Healthcare Mater. 14/2016).

    PubMed

    Di Luca, Andrea; Lorenzo-Moldero, Ivan; Mota, Carlos; Lepedda, Antonio; Auhl, Dietmar; Van Blitterswijk, Clemens; Moroni, Lorenzo

    2016-07-01

    A combination of human mesenchymal stem cells with additive manufacturing technology for the fabrication of scaffolds with instructive properties is presented by Lorenzo Moroni and co-workers on page 1753. This new fiber deposition pattern allows the generation of pores of different shapes within the same construct. The most rhomboidal pore geometry sustained enhances alkaline phosphatase activity and osteogenic related genes expression with respect to the other gradient zones when the gradient scaffold is cultured in a medium supporting both osteogenic and chondrogenic differentiation. This may contribute to enhance osteochondral regeneration in orthopedic treatments. PMID:27436107

  8. SERS spectroscopy, electrical recording and intracellular injection in neuronal networks with 3D plasmonic nanoantennas

    NASA Astrophysics Data System (ADS)

    Caprettini, Valeria; Messina, Gabriele C.; Dipalo, Michele; La Rocca, Rosanna; Cerea, Andrea; De Angelis, Francesco

    2016-03-01

    We developed a platform based on 3D plasmonic nanoantennas able to perform different functions with applications in the biological research area. In particular it will be shown how the peculiar geometry of the system plays a fundamental role, leading to a tight interaction with the cellular membrane. Such configuration allows on one side the investigation of extracellular features through enhanced vibrational spectroscopy and electrical recording, and on the other the possibility of intracellular injection by optoporation. In this regard it will be demonstrated how the characteristics of the laser pulse used for exciting the antenna establish the kind of involved phenomena. A dependence of these properties on the metal coating the antenna will be also shown.

  9. Efficient Data Gathering in 3D Linear Underwater Wireless Sensor Networks Using Sink Mobility

    PubMed Central

    Akbar, Mariam; Javaid, Nadeem; Khan, Ayesha Hussain; Imran, Muhammad; Shoaib, Muhammad; Vasilakos, Athanasios

    2016-01-01

    Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability. PMID:27007373

  10. Efficient Data Gathering in 3D Linear Underwater Wireless Sensor Networks Using Sink Mobility.

    PubMed

    Akbar, Mariam; Javaid, Nadeem; Khan, Ayesha Hussain; Imran, Muhammad; Shoaib, Muhammad; Vasilakos, Athanasios

    2016-01-01

    Due to the unpleasant and unpredictable underwater environment, designing an energy-efficient routing protocol for underwater wireless sensor networks (UWSNs) demands more accuracy and extra computations. In the proposed scheme, we introduce a mobile sink (MS), i.e., an autonomous underwater vehicle (AUV), and also courier nodes (CNs), to minimize the energy consumption of nodes. MS and CNs stop at specific stops for data gathering; later on, CNs forward the received data to the MS for further transmission. By the mobility of CNs and MS, the overall energy consumption of nodes is minimized. We perform simulations to investigate the performance of the proposed scheme and compare it to preexisting techniques. Simulation results are compared in terms of network lifetime, throughput, path loss, transmission loss and packet drop ratio. The results show that the proposed technique performs better in terms of network lifetime, throughput, path loss and scalability. PMID:27007373

  11. SnS2 nanoplates embedded in 3D interconnected graphene network as anode material with superior lithium storage performance

    NASA Astrophysics Data System (ADS)

    Tang, Hongli; Qi, Xiang; Han, Weijia; Ren, Long; Liu, Yundan; Wang, Xingyan; Zhong, Jianxin

    2015-11-01

    Three-dimensional (3D) interconnected graphene network embedded with uniformly distributed tin disulfide (SnS2) nanoplates was prepared by a facile two-step method. The microstructures and morphologies of the SnS2/graphene nanocomposite (SSG) are experimentally confirmed by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using the as-prepared SSG as an anode material for lithium batteries, its electrochemical performances were investigated by cyclic voltammograms (CV), charge/discharge tests, galvanostatic cycling performance and AC impedance spectroscopy. The results demonstrate that the as-prepared SSG exhibits excellent cycling performance with a capacity of 1060 mAh g-1 retained after 200 charge/discharge cycles at a current density of 100 mA g-1, also a superior rate capability of 670 mAh g-1 even at such a high current density of 2000 mA g-1. This favorable performance can be attributed to the unique 3D interconnected architecture with great electro-conductivity and its intimate contact with SnS2. Our results indicate a potential application of this novel 3D SnS2/graphene nanocomposite in lithium-ion battery.

  12. Direct pore-to-core up-scaling of displacement processes: Dynamic pore network modeling and experimentation

    NASA Astrophysics Data System (ADS)

    Aghaei, Arash; Piri, Mohammad

    2015-03-01

    We present a new dynamic pore network model that is capable of up-scaling two-phase flow processes from pore to core. This dynamic model provides a platform to study various flow processes in porous media at the core scale using the pore-scale physics. The most critical features of this platform include (1) the incorporation of viscous, capillary, and gravity pressure drops in pore-scale displacement thresholds, (2) wetting-phase corner flow in capillary elements with angular cross-sections, (3) adjustments of corner interfaces between wetting and non-wetting phases based on changes in local capillary pressure, (4) simultaneous injection of wetting and non-wetting phases from the inlet of the medium at constant flow rates that makes the study of steady-state processes possible, (5) heavy parallelization using a three-dimensional domain decomposition scheme that enables the study of two-phase flow at the core scale, and (6) constant pressure boundary condition at the outlet. For the validation of the dynamic model, three two-phase miniature core-flooding experiments were performed in a state-of-the-art micro core-flooding system integrated with a high-resolution X-ray micro-CT scanner. The dynamic model was rigorously validated by comparing the predicted local saturation profiles, fractional flow curves, relative permeabilities, and residual oil saturations against their experimental counterparts. The validated dynamic model was then used to study low-IFT and high-viscosity two-phase flow processes and investigate the effect of high capillary number on relative permeabilities and residual oil saturation.

  13. AxeCorp's "Team Challenge": Teaching Teamwork via 3D Social Networking Platforms

    ERIC Educational Resources Information Center

    Carmichael, Kendra

    2011-01-01

    To prepare business communication undergraduates for a changing work world and to engage today's tech-savvy students, many instructors have embraced social media by incorporating its use in the classroom. This article describes AxeCorp, a fictional company headquartered on the immersive social networking platform, Second Life, and one particular…

  14. Volume learning algorithm artificial neural networks for 3D QSAR studies.

    PubMed

    Tetko, I V; Kovalishyn, V V; Livingstone, D J

    2001-07-19

    The current study introduces a new method, the volume learning algorithm (VLA), for the investigation of three-dimensional quantitative structure-activity relationships (QSAR) of chemical compounds. This method incorporates the advantages of comparative molecular field analysis (CoMFA) and artificial neural network approaches. VLA is a combination of supervised and unsupervised neural networks applied to solve the same problem. The supervised algorithm is a feed-forward neural network trained with a back-propagation algorithm while the unsupervised network is a self-organizing map of Kohonen. The use of both of these algorithms makes it possible to cluster the input CoMFA field variables and to use only a small number of the most relevant parameters to correlate spatial properties of the molecules with their activity. The statistical coefficients calculated by the proposed algorithm for cannabimimetic aminoalkyl indoles were comparable to, or improved, in comparison to the original study using the partial least squares algorithm. The results of the algorithm can be visualized and easily interpreted. Thus, VLA is a new convenient tool for three-dimensional QSAR studies. PMID:11448223

  15. The impact of wettability and connectivity on relative permeability in carbonates: A pore network modeling analysis

    NASA Astrophysics Data System (ADS)

    Gharbi, Oussama; Blunt, Martin J.

    2012-12-01

    We use pore network modeling to study the impact of wettability and connectivity on waterflood relative permeability for a set of six carbonate samples. Four quarry samples are studied, Indiana, Portland, Guiting, and Mount Gambier, along with two subsurface samples obtained from a deep saline Middle Eastern aquifer. The pore space is imaged in three dimensions using X-ray microtomography at a resolution of a few microns. The images are segmented into pore and solid, and a topologically representative network of pores and throats is extracted from these images. We then simulate quasi-static displacement in the networks. We represent mixed-wet behavior by varying the oil-wet fraction of the pore space. The relative permeability is strongly dependent on both the wettability and the average coordination number of the network. We show that traditional measures of wettability based on the point where the relative permeability curves cross are not reliable. Good agreement is found between our calculations and measurements of relative permeability on carbonates in the literature. This work helps establish a library of benchmark samples for multiphase flow and transport computations. The implications of the results for field-scale displacement mechanisms are discussed, and the efficiency of waterflooding as an oil recovery process in carbonate reservoirs is assessed depending on the wettability and pore space connectivity.

  16. A hydrogen bonded molecular capsule versus a 3D network of tripodal organopolysilanols.

    PubMed

    Fukawa, Marina; Sato, Takayuki; Kabe, Yoshio

    2015-10-11

    1,3,5-Triethylbenzene based tripodal trisilanols were synthesized. The X-ray crystal structures of trisilanols showed capsule formation as well as non-capsular network formation using silanol hydrogen bonds. The (1)H NMR and ESI-mass spectroscopy experiments for solution state binding supported encapsulation of the halide ions in the cavity of the molecular capsule with a C3 symmetry. PMID:26295069

  17. Automatic delineation and 3D visualization of the human ventricular system using probabilistic neural networks

    NASA Astrophysics Data System (ADS)

    Hatfield, Fraser N.; Dehmeshki, Jamshid

    1998-09-01

    Neurosurgery is an extremely specialized area of medical practice, requiring many years of training. It has been suggested that virtual reality models of the complex structures within the brain may aid in the training of neurosurgeons as well as playing an important role in the preparation for surgery. This paper focuses on the application of a probabilistic neural network to the automatic segmentation of the ventricles from magnetic resonance images of the brain, and their three dimensional visualization.

  18. Organ-wide 3D-imaging and topological analysis of the continuous microvascular network in a murine lymph node

    PubMed Central

    Kelch, Inken D.; Bogle, Gib; Sands, Gregory B.; Phillips, Anthony R. J.; LeGrice, Ian J.; Rod Dunbar, P.

    2015-01-01

    Understanding of the microvasculature has previously been limited by the lack of methods capable of capturing and modelling complete vascular networks. We used novel imaging and computational techniques to establish the topology of the entire blood vessel network of a murine lymph node, combining 63706 confocal images at 2 μm pixel resolution to cover a volume of 3.88 mm3. Detailed measurements including the distribution of vessel diameters, branch counts, and identification of voids were subsequently re-visualised in 3D revealing regional specialisation within the network. By focussing on critical immune microenvironments we quantified differences in their vascular topology. We further developed a morphology-based approach to identify High Endothelial Venules, key sites for lymphocyte extravasation. These data represent a comprehensive and continuous blood vessel network of an entire organ and provide benchmark measurements that will inform modelling of blood vessel networks as well as enable comparison of vascular topology in different organs. PMID:26567707

  19. Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

    SciTech Connect

    Shi, Fa-Nian; Rosa Silva, Ana; Bian, Liang

    2015-05-15

    A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi{sub 2}O(1,3,5-BTC){sub 2}]{sub n} (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi{sub 4}O{sub 2}(COO){sub 12} clusters which are further connected to Mn(COO){sub 6} fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4{sup 13}.6{sup 2})(4{sup 13}.6{sup 8})(4{sup 16}.6{sup 5})(4{sup 18}.6{sup 10})(4{sup 22}.6{sup 14})(4{sup 3}) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles.

  20. Mixed-scale channel networks including Kingfisher-beak-shaped 3D microfunnels for efficient single particle entrapment.

    PubMed

    Lee, Yunjeong; Lim, Yeongjin; Shin, Heungjoo

    2016-06-01

    Reproducible research results for nanofluidics and their applications require viable fabrication technologies to produce nanochannels integrated with microchannels that can guide fluid flow and analytes into/out of the nanochannels. We present the simple fabrication of mixed-scale polydimethylsiloxane (PDMS) channel networks consisting of nanochannels and microchannels via a single molding process using a monolithic mixed-scale carbon mold. The monolithic carbon mold is fabricated by pyrolyzing a polymer mold patterned by photolithography. During pyrolysis, the polymer mold shrinks by ∼90%, which enables nanosized carbon molds to be produced without a complex nanofabrication process. Because of the good adhesion between the polymer mold and the Si substrate, non-uniform volume reduction occurs during pyrolysis resulting in the formation of curved carbon mold side walls. These curved side walls and the relatively low surface energy of the mold provide efficient demolding of the PDMS channel networks. In addition, the trigonal prismatic shape of the polymer is converted into to a Kingfisher-beak-shaped carbon structure due to the non-uniform volume reduction. The transformation of this mold architecture produces a PDMS Kingfisher-beak-shaped 3D microfunnel that connects the microchannel and the nanochannel smoothly. The smooth reduction in the cross-sectional area of the 3D microfunnels enables efficient single microparticle trapping at the nanochannel entrance; this is beneficial for studies of cell transfection. PMID:27279423

  1. Engineering interconnected 3D vascular networks in hydrogels using molded sodium alginate lattice as the sacrificial template.

    PubMed

    Wang, Xue-Ying; Jin, Zi-He; Gan, Bo-Wen; Lv, Song-Wei; Xie, Min; Huang, Wei-Hua

    2014-08-01

    Engineering 3D perfusable vascular networks in vitro and reproducing the physiological environment of blood vessels is very challenging for tissue engineering and investigation of blood vessel function. Here, we engineer interconnected 3D microfluidic vascular networks in hydrogels using molded sodium alginate lattice as sacrificial templates. The sacrificial templates are rapidly replicated in polydimethylsiloxane (PDMS) microfluidic chips via Ca⁺²-crosslinking and then fully encapsulated in hydrogels. Interconnected channels with well controlled size and morphology are obtained by dissolving the monolayer or multilayer templates with EDTA solution. The human umbilical vein endothelial cells (HUVECs) are cultured on the channel linings and proliferated to form vascular lumens. The strong cell adhesion capability and adaptive response to shear stress demonstrate the excellent cytocompatibility of both the template and template-sacrificing process. Furthermore, the barrier function of the endothelial layer is characterized and the results show that a confluent endothelial monolayer is fully developed. Taken together, we develop a facile and rapid approach to engineer a vascular model that could be potentially used in physiological studies of vascular functions and vascular tissue engineering. PMID:24887141

  2. Simultaneous submicrometric 3D imaging of the micro-vascular network and the neuronal system in a mouse spinal cord

    NASA Astrophysics Data System (ADS)

    Fratini, Michela; Bukreeva, Inna; Campi, Gaetano; Brun, Francesco; Tromba, Giuliana; Modregger, Peter; Bucci, Domenico; Battaglia, Giuseppe; Spanò, Raffaele; Mastrogiacomo, Maddalena; Requardt, Herwig; Giove, Federico; Bravin, Alberto; Cedola, Alessia

    2015-02-01

    Faults in vascular (VN) and neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and neuronal system represents a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and neuronal systems of ex-vivo mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with nor contrast agent nor sectioning and neither destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is very suitable for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries, in particular to resolve the entangled relationship between VN and neuronal system.

  3. PEG-diacrylate/hyaluronic acid semi-interpenetrating network compositions for 3D cell spreading and migration

    PubMed Central

    Lee, Ho-Joon; Sen, Atanu; Bae, Sooneon; Lee, Jeoung Soo; Webb, Ken

    2015-01-01

    To serve as artificial matrices for therapeutic cell transplantation, synthetic hydrogels must incorporate mechanisms enabling localized, cell-mediated degradation that allows cell spreading and migration. Previously, we have shown that hybrid semi-interpenetrating polymer networks (semi-IPNs) composed of hydrolytically degradable PEG-diacrylates (PEGdA), acrylate-PEG-GRGDS, and native hyaluronic acid (HA) support increased cell spreading relative to fully synthetic networks that is dependent on cellular hyaluronidase activity. This study systematically investigated the effects of PEGdA/HA semi-IPN network composition on 3D spreading of encapsulated fibroblasts, the underlying changes in gel structure responsible for this activity, and the ability of optimized gel formulations to support long-term cell survival and migration. Fibroblast spreading exhibited a biphasic response to HA concentration, required a minimum HA molecular weight, decreased with increasing PEGdA concentration, and was independent of hydrolytic degradation at early time points. Increased gel turbidity was observed in semi-IPNs, but not in copolymerized hydrogels containing methacrylated HA that did not support cell spreading; suggesting an underlying mechanism of polymerization-induced phase separation resulting in HA-enriched defects within the network structure. PEGdA/HA semi-IPNs were also able to support cell spreading at relatively high levels of mechanical properties (~10 kPa elastic modulus) compared to alternative hybrid hydrogels. In order to support long-term cellular remodeling, the degradation rate of the PEGdA component was optimized by preparing blends of three different PEGdA macromers with varying susceptibility to hydrolytic degradation. Optimized semi-IPN formulations supported long-term survival of encapsulated fibroblasts and sustained migration in a gel-within-gel encapsulation model. These results demonstrate that PEGdA/HA semi-IPNs provide dynamic microenvironments that

  4. Minimum cross-sectional stream power as the criteria of shaping 3-D network-scale landscape

    NASA Astrophysics Data System (ADS)

    Paik, K.

    2008-12-01

    It has been widely accepted that the minimum total energy expenditure (MTEE) [Rodríguez-Iturbe et al., 1992] is the important tendency in the formation of self-similar tree river networks. However, this formulation has simplified the 3-D nature of landscape adaptation as a 2-D network connectivity problem. As a result, MTEE cannot capture other signatures of landform such as meandering. This leads to an idea that there could be another optimality condition which can better represent landscape evolution than MTEE. In this study, I focused on the theory of minimum cross-sectional stream power (MCSP) [Chang and Hill, 1977] which has been successfully used in channel-scale problems. I investigated the applicability of this rule of MCSP to the network-scale landscape formation. To test this idea, I devised a dynamic 2-D genetic algorithm which can handle the adaptation of 3-D landscape over time. The result shows that the landscape formed under the criteria of both MCSP and MTEE exhibit self-similar tree structure of natural river networks. However, the landscape formed by MCSP criteria also exhibits the meandering pattern of natural streams, which cannot be captured by MTEE. Chang, H. H., and J. C. Hill (1977), Minimum stream power for rivers and deltas, Journal of the Hydraulics Division (ASCE), 103, 1375--1389. Rodríguez-Iturbe, I., A. Rinaldo, R. Rigon, R. L. Bras, A. Marani, and E. J. Ijjasz-Váquez (1992), Energy dissipation, runoff production, and the three-dimensional structure of river basins, Water Resour. Res., 28, 1095--1103.

  5. A combined fuzzy-neural network model for non-linear prediction of 3-D rendering workload in grid computing.

    PubMed

    Doulamis, Nikolaos D; Doulamis, Anastasios D; Panagakis, Athanasios; Dolkas, Konstantinos; Varvarigou, Theodora A; Varvarigos, Emmanuel

    2004-04-01

    Implementation of a commercial application to a grid infrastructure introduces new challenges in managing the quality-of-service (QoS) requirements, most stem from the fact that negotiation on QoS between the user and the service provider should strictly be satisfied. An interesting commercial application with a wide impact on a variety of fields, which can benefit from the computational grid technologies, is three-dimensional (3-D) rendering. In order to implement, however, 3-D rendering to a grid infrastructure, we should develop appropriate scheduling and resource allocation mechanisms so that the negotiated (QoS) requirements are met. Efficient scheduling schemes require modeling and prediction of rendering workload. In this paper workload prediction is addressed based on a combined fuzzy classification and neural network model. Initially, appropriate descriptors are extracted to represent the synthetic world. The descriptors are obtained by parsing RIB formatted files, which provides a general structure for describing computer-generated images. Fuzzy classification is used for organizing rendering descriptor so that a reliable representation is accomplished which increases the prediction accuracy. Neural network performs workload prediction by modeling the nonlinear input-output relationship between rendering descriptors and the respective computational complexity. To increase prediction accuracy, a constructive algorithm is adopted in this paper to train the neural network so that network weights and size are simultaneously estimated. Then, a grid scheduler scheme is proposed to estimate the queuing order that the tasks should be executed and the most appopriate processor assignment so that the demanded QoS are satisfied as much as possible. A fair scheduling policy is considered as the most appropriate. Experimental results on a real grid infrastructure are presented to illustrate the efficiency of the proposed workload prediction--scheduling algorithm

  6. Pore-network study of bubble growth in porous media driven by heat transfer

    SciTech Connect

    Satik, C.; Yortsos, Y.C.

    1996-05-01

    We present experimental and theoretical investigations of vapor phase growth in pore-network models of porous media. Visualization experiments of boiling of ethyl alcohol in horizontal etched-glass micromodels were conducted. The vapor phase was observed to grow into a disordered pattern following a sequence of pressurization and pore-filling steps. At sufficiently small cluster sizes, growth occurred `one pore at a time,` leading to invasion percolation patterns. Single-bubble (cluster) growth was next simulated with a pore-network simulator that includes heat transfer (convection and conduction), and capillary and viscous forces, although not gravity. A boundary in the parameter space was delineated that separates patterns of growth dictated solely by capillarity (invasion percolation) from other patterns. The region of validity of invasion percolation was found to decrease as the supersaturation (heat flux), the capillary number, the thermal diffusivity, and the vapor cluster size increase. Implications to continuum models are discussed. 33 refs., 9 figs.

  7. Incorporating Discrete Irregular Fracture Zone Networks into 3D Paleohydrogeologic Simulations

    NASA Astrophysics Data System (ADS)

    Normani, S. D.

    2015-12-01

    Dual continuum computational models which include both porous media and discrete fracture zones are valuable tools in assessing groundwater migration and pathways in fractured rock systems. Fracture generation models can produce stochastic realizations of fracture networks which honor geological structures and fracture propagation behaviors. Surface lineament traces can be propagated to depth based on fracture zone statistics to produce representations of geological structures in rock. The generated discrete, complex and irregular fracture zone networks, represented as a triangulated mesh, are embedded using orthogonal quadrilateral elements within a three-dimensional hexahedral finite element mesh. A detailed coupled density-dependent paleohydrogeologic groundwater analysis of a hypothetical 104 km2 portion of the Canadian Shield has been conducted using the discrete-fracture dual continuum finite element model FRAC3DVS to investigate the characterization of large-scale fracture zone networks on groundwater and tracer movement during a 120,000 year paleoclimate cycle. Permeability reduction due to permafrost was also applied. Time series data for the depth of permafrost, along with ice thickness and lake depth, were provided by the University of Toronto (UofT) Glacial Systems Model. The crystalline rock between fracture zones was assigned properties characteristic of those reported for the Canadian Shield. Total dissolved solids concentrations of 300 g/L are encountered at depth. Surface water features and a Digital Elevation Model (DEM) were used in a GIS framework to define the watershed boundaries at surface water divides and to populate the finite element mesh. This work will illustrate the long-term evolution and stability of the geosphere and groundwater systems to external perturbations caused by glaciation through the use of performance measures such as Mean Life Expectancy and the migration of a unit tracer to depth over a paleoclimate cycle.

  8. The 3-D image recognition based on fuzzy neural network technology

    NASA Technical Reports Server (NTRS)

    Hirota, Kaoru; Yamauchi, Kenichi; Murakami, Jun; Tanaka, Kei

    1993-01-01

    Three dimensional stereoscopic image recognition system based on fuzzy-neural network technology was developed. The system consists of three parts; preprocessing part, feature extraction part, and matching part. Two CCD color camera image are fed to the preprocessing part, where several operations including RGB-HSV transformation are done. A multi-layer perception is used for the line detection in the feature extraction part. Then fuzzy matching technique is introduced in the matching part. The system is realized on SUN spark station and special image input hardware system. An experimental result on bottle images is also presented.

  9. A novel architecture for pore network modelling with applications to permeability of porous media

    NASA Astrophysics Data System (ADS)

    Jivkov, Andrey P.; Hollis, Cathy; Etiese, Friday; McDonald, Samuel A.; Withers, Philip J.

    2013-04-01

    SummaryNetwork models of porous media are beneficial for predicting the evolution of macroscopic mass transport properties. This work proposes a novel bi-regular network model based on truncated octahedral support. With the model, pore systems with different pore coordination spectra for a given average coordination number can be constructed to match experimental data. This feature and the maximum allowed pore coordination of 14 make the proposed model more realistic and flexible than the existing models based on cubic supports. Limestone is used as a study material to illustrate the model performance. Experimental pore space data for this material obtained by X-ray tomography (CT) are used for constructing microstructure-informed model realisations. It is demonstrated that with these realisations the experimentally measured permeability of the material can be predicted. The model is further used to assess the effects of pore connectivity and porosity on the permeability. It is shown that the effect of pore connectivity is substantially stronger than the effect of porosity. A strategy for calculating the evolution of permeability with damage-related pore space changes is also described. The results reveal the effects of the mechanical properties of the medium on the permeability evolution as a function of damage evolution. Developments of this strategy are suggested for deriving mechanism-based constitutive laws for engineering applications.

  10. 3D functional and perfusable microvascular networks for organotypic microfluidic models.

    PubMed

    Bersini, Simone; Moretti, Matteo

    2015-05-01

    The metastatic dissemination of cancer cells from primary tumors to secondary loci is a complex and multistep process including local invasion, intravasation, survival in the blood stream and extravasation towards the metastatic site. It is well known cancer metastases follow organ-specific pathways with selected primary tumors mainly metastasizing towards a specific panel of secondary organs (Steven Paget's theory 1889). However, circulatory patterns and microarchitecture of capillary networks play a key role in the metastatic spread as well (James Ewing's theory 1929). Taking into account both these factors would be critical to develop more complex and physiologically relevant in vitro cancer models. This review presents recent advances in the generation of microvascularized systems through microfluidic approaches and discusses promising results achieved by organ-on-a-chip platforms mimicking the pathophysiology of the functional units of specific organs. The combination of physiologically-like microvascular networks and organotypic microenvironments would foster a new generation of in vitro cancer models to more effectively screen new therapeutics, design personalized medicine treatments and investigate molecular pathways involved in cancer metastases. PMID:25893395

  11. Analysis of quasi-periodic pore-network structure of centric marine diatom frustules

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory A.; Alvarez, Christine E.; Meyers, Keith; Deheyn, Dimitri D.; Hildebrand, Mark; Kieu, Khanh; Norwood, Robert A.

    2015-03-01

    Diatoms are a common type of phytoplankton characterized by their silica exoskeleton known as a frustule. The diatom frustule is composed of two valves and a series of connecting girdle bands. Each diatom species has a unique frustule shape and valves in particular species display an intricate pattern of pores resembling a photonic crystal structure. We used several numerical techniques to analyze the periodic and quasi-periodic valve pore-network structure in diatoms of the Coscinodiscophyceae order. We quantitatively identify defect locations and pore spacing in the valve and use this information to better understand the optical and biological properties of the diatom.

  12. Comparison of caprock pore networks which potentially will be impacted by carbon sequestration projects

    NASA Astrophysics Data System (ADS)

    Mouzakis, K. M.; Sitchler, A.; McCray, J. E.; Rother, G.; Dewers, T.; Heath, J. E.

    2010-12-01

    Injection of CO2 into underground rock formations can reduce atmospheric CO2 emissions. Caprocks present above potential storage formations are the main structural trap inhibiting CO2 from leaking into overlying aquifers or back to the Earth’s surface. Dissolution and precipitation of caprock minerals resulting from reaction with CO2 may alter the pore network where many pores are of the micrometer to nanometer scale, thus altering the structural trapping potential of the caprock. However, the distribution, geometry and volume of pores at these scales are poorly characterized. In order to evaluate the overall risk of leakage of CO2 from storage formations, a first critical step is understanding the distribution and shape of pores in a variety of different caprocks. As the caprock is often comprised of mudstones, we analyzed samples from several mudstone formations with small angle neutron scattering (SANS) and high-resolution transmission electron microscopy (TEM) imaging to compare the pore networks. Mudstones were chosen from current or potential sites for carbon sequestration projects including the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Expandable clay contents ranged from 10% to approximately 40% in the Gothic shale and Kirtland Formation, respectively. During SANS, neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e., minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume and arrangement of pores in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. On such plots slopes from -2 to -3 represent mass fractals while slopes from -3 to -4 represent surface fractals. Scattering data showed surface fractal dimensions for

  13. Comparison of caprock pore networks which potentially will be impacted by carbon sequestration projects.

    SciTech Connect

    McCray, John; Navarre-Sitchler, Alexis; Mouzakis, Katherine; Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot

    2010-12-01

    Injection of CO2 into underground rock formations can reduce atmospheric CO2 emissions. Caprocks present above potential storage formations are the main structural trap inhibiting CO2 from leaking into overlying aquifers or back to the Earth's surface. Dissolution and precipitation of caprock minerals resulting from reaction with CO2 may alter the pore network where many pores are of the micrometer to nanometer scale, thus altering the structural trapping potential of the caprock. However, the distribution, geometry and volume of pores at these scales are poorly characterized. In order to evaluate the overall risk of leakage of CO2 from storage formations, a first critical step is understanding the distribution and shape of pores in a variety of different caprocks. As the caprock is often comprised of mudstones, we analyzed samples from several mudstone formations with small angle neutron scattering (SANS) and high-resolution transmission electron microscopy (TEM) imaging to compare the pore networks. Mudstones were chosen from current or potential sites for carbon sequestration projects including the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Expandable clay contents ranged from 10% to approximately 40% in the Gothic shale and Kirtland Formation, respectively. During SANS, neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e., minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume and arrangement of pores in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. On such plots slopes from -2 to -3 represent mass fractals while slopes from -3 to -4 represent surface fractals. Scattering data showed surface fractal dimensions for

  14. Coupling root architecture and pore network modeling - an attempt towards better understanding root-soil interactions

    NASA Astrophysics Data System (ADS)

    Leitner, Daniel; Bodner, Gernot; Raoof, Amir

    2013-04-01

    Understanding root-soil interactions is of high importance for environmental and agricultural management. Root uptake is an essential component in water and solute transport modeling. The amount of groundwater recharge and solute leaching significantly depends on the demand based plant extraction via its root system. Plant uptake however not only responds to the potential demand, but in most situations is limited by supply form the soil. The ability of the plant to access water and solutes in the soil is governed mainly by root distribution. Particularly under conditions of heterogeneous distribution of water and solutes in the soil, it is essential to capture the interaction between soil and roots. Root architecture models allow studying plant uptake from soil by describing growth and branching of root axes in the soil. Currently root architecture models are able to respond dynamically to water and nutrient distribution in the soil by directed growth (tropism), modified branching and enhanced exudation. The porous soil medium as rooting environment in these models is generally described by classical macroscopic water retention and sorption models, average over the pore scale. In our opinion this simplified description of the root growth medium implies several shortcomings for better understanding root-soil interactions: (i) It is well known that roots grow preferentially in preexisting pores, particularly in more rigid/dry soil. Thus the pore network contributes to the architectural form of the root system; (ii) roots themselves can influence the pore network by creating preferential flow paths (biopores) which are an essential element of structural porosity with strong impact on transport processes; (iii) plant uptake depend on both the spatial location of water/solutes in the pore network as well as the spatial distribution of roots. We therefore consider that for advancing our understanding in root-soil interactions, we need not only to extend our root models

  15. Methods for colloid transport visualization in pore networks

    NASA Astrophysics Data System (ADS)

    Ochiai, Naoyuki; Kraft, Erika L.; Selker, John S.

    2006-12-01

    Prediction of colloid transport in the subsurface is relevant to researchers in a variety of fields such as contaminant transport, wastewater treatment, and bioremediation. Investigations have traditionally relied on column studies whereby mechanistic inferences must be drawn on the basis of colloid behavior at the outlet. Over the past decade, development of noninvasive visualization techniques based on visible light, magnetic resonance, and X rays have provided insight into a number of colloid transport mechanisms by enabling direct observation of individual colloids at the pore scale and colloid concentrations at longer length scales. As research focus shifts from transport of ideal colloids in ideal media such as glass beads to natural colloids in natural porous media, these noninvasive techniques will become increasingly useful for studying the collection of mechanisms at work in heterogeneous pore systems. It is useful at this juncture to review recent progress in colloid transport visualization as a starting point for further development of visualization tools to support investigation of colloids in natural systems. We briefly discuss characteristics of visualization systems currently used to study colloid transport in porous media and review representative microscale and mesoscale visualization studies conducted over the past decade, with additional attention given to two optical visualization systems being developed by the authors.

  16. 3-D multilateration for measurement of earth crustal deformation and network densification

    NASA Technical Reports Server (NTRS)

    Ong, K. M.

    1973-01-01

    Discussion of how range and range-difference data types can make possible precise three-dimensional measurement of ground station positions and the position of an artificial signal source, without explicit dependence upon the signal source trajectory. An effective strategy for such measurement is to combine the multilateration approach with a VLBI system using natural radio sources. The VLBI methods would provide a coarse grid of three-dimensional benchmark locations on a regional and global scale. Multilateration stations would then occupy these coarse grid locations and provide a means for highly portable, relatively low-cost units to then densify networks on a regional and local scale. Because a multilateration approach can make use of strong artificial radio sources, it makes possible the use of relatively low-cost, highly mobile stations. Such mobile stations are virtually essential for three dimensional surveying in heavily urbanized areas or in rugged terrain.

  17. Combining high-performance computing and networking for advanced 3-D cardiac imaging.

    PubMed

    Santarelli, M F; Positano, V; Landini, L

    2000-03-01

    This paper deals with the integration of a powerful parallel computer-based image analysis and visualization system for cardiology into a hospital information system. Further services are remote access to the hospital Web server through an internet network. The visualization system includes dynamic three-dimensional representation of two types of medical images (e.g., magnetic resonance and nuclear medicine) as well as two images in the same modality (e.g., basal versus stress images). A series of software tools for quantitative image analysis developed for supporting diagnosis of cardiac disease are also available, including automated image segmentation and quantitative time evaluation of left ventricular volumes and related indices during cardiac cycle, myocardial mass, and myocardial perfusion indices. The system has been tested both at a specialized cardiologic center and for remote consultation in diagnosis of cardiac disease by using anatomical and perfusion magnetic resonance images. PMID:10761775

  18. Dynamic network morphology and tension buildup in a 3D model of cytokinetic ring assembly.

    PubMed

    Bidone, Tamara C; Tang, Haosu; Vavylonis, Dimitrios

    2014-12-01

    During fission yeast cytokinesis, actin filaments nucleated by cortical formin Cdc12 are captured by myosin motors bound to a band of cortical nodes and bundled by cross-linking proteins. The myosin motors exert forces on the actin filaments, resulting in a net pulling of the nodes into a contractile ring, while cross-linking interactions help align actin filaments and nodes into a single bundle. We used these mechanisms in a three-dimensional computational model of contractile ring assembly, with semiflexible actin filaments growing from formins at cortical nodes, capturing of filaments by neighboring nodes, and cross-linking among filaments through attractive interactions. The model was used to predict profiles of actin filament density at the cell cortex, morphologies of condensing node-filament networks, and regimes of cortical tension by varying the node pulling force and strength of cross-linking among actin filaments. Results show that cross-linking interactions can lead to confinement of actin filaments at the simulated cortical boundary. We show that the ring-formation region in parameter space lies close to regions leading to clumps, meshworks or double rings, and stars/cables. Since boundaries between regions are not sharp, transient structures that resemble clumps, stars, and meshworks can appear in the process of ring assembly. These results are consistent with prior experiments with mutations in actin-filament turnover regulators, myosin motor activity, and changes in the concentration of cross-linkers that alter the morphology of the condensing network. Transient star shapes appear in some simulations, and these morphologies offer an explanation for star structures observed in prior experimental images. Finally, we quantify tension along actin filaments and forces on nodes during ring assembly and show that the mechanisms describing ring assembly can also drive ring constriction once the ring is formed. PMID:25468341

  19. 3-D RESERVOIR AND STOCHASTIC FRACTURE NETWORK MODELING FOR ENHANCED OIL RECOVERY, CIRCLE RIDGE PHOSPHORIA/TENSLEEP RESERVOIR, WIND RIVER RESERVATION, ARAPAHO AND SHOSHONE TRIBES, WYOMING

    SciTech Connect

    Paul La Pointe; Jan Hermanson; Robert Parney; Thorsten Eiben; Mike Dunleavy; Ken Steele; John Whitney; Darrell Eubanks; Roger Straub

    2002-11-18

    This report describes the results made in fulfillment of contract DE-FG26-00BC15190, ''3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, Wind River Reservation, Arapaho and Shoshone Tribes, Wyoming''. The goal of this project is to improve the recovery of oil from the Tensleep and Phosphoria Formations in Circle Ridge Oilfield, located on the Wind River Reservation in Wyoming, through an innovative integration of matrix characterization, structural reconstruction, and the characterization of the fracturing in the reservoir through the use of discrete fracture network models. Fields in which natural fractures dominate reservoir permeability, such as the Circle Ridge Field, often experience sub-optimal recovery when recovery processes are designed and implemented that do not take advantage of the fracture systems. For example, a conventional waterflood in a main structural block of the Field was implemented and later suspended due to unattractive results. It is estimated that somewhere less than 20% of the OOIP in the Circle Ridge Field have been recovered after more than 50 years' production. Marathon Oil Company identified the Circle Ridge Field as an attractive candidate for several advanced IOR processes that explicitly take advantage of the natural fracture system. These processes require knowledge of the distribution of matrix porosity, permeability and oil saturations; and understanding of where fracturing is likely to be well-developed or poorly developed; how the fracturing may compartmentalize the reservoir; and how smaller, relatively untested subthrust fault blocks may be connected to the main overthrust block. For this reason, the project focused on improving knowledge of the matrix properties, the fault block architecture and to develop a model that could be used to predict fracture intensity, orientation and fluid flow/connectivity properties. Knowledge of matrix properties was

  20. Capillary effects in drainage in heterogeneous porous media: Continuum modeling, experiments and pore network simulations

    SciTech Connect

    Xu, Baomin; Yortsos, Y.C.

    1993-04-01

    We investigate effects of capillary heterogeneity induced by variations in permeability in the direction of displacement in heterogeneous porous media under drainage conditions. The investigation is three-pronged and uses macroscopic simulation, based on the standard continuum equations, experiments with the use of an acoustic technique and pore network numerical models. It is found that heterogeneity affects significantly the saturation profiles, the effect being stronger at lower rates. A good agreement is found between the continuum model predictions and the experimental results based on which it can be concluded that capillary heterogeneity effects in the direction of displacement act much like a body force (e.g. gravity). A qualitative agreement is also found between the continuum approach and the pore network numerical models, which is expected to improve when finite size effects in the pore network simulations diminish. The results are interpreted with the use of invasion percolation concepts.

  1. Analysis of performance improvements for host and GPU interface of the APENet+ 3D Torus network

    NASA Astrophysics Data System (ADS)

    Ammendola A, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Lonardo, A.; Paolucci, P. S.; Rossetti, D.; Simula, F.; Tosoratto, L.; Vicini, P.

    2014-06-01

    APEnet+ is an INFN (Italian Institute for Nuclear Physics) project aiming to develop a custom 3-Dimensional torus interconnect network optimized for hybrid clusters CPU-GPU dedicated to High Performance scientific Computing. The APEnet+ interconnect fabric is built on a FPGA-based PCI-express board with 6 bi-directional off-board links showing 34 Gbps of raw bandwidth per direction, and leverages upon peer-to-peer capabilities of Fermi and Kepler-class NVIDIA GPUs to obtain real zero-copy, GPU-to-GPU low latency transfers. The minimization of APEnet+ transfer latency is achieved through the adoption of RDMA protocol implemented in FPGA with specialized hardware blocks tightly coupled with embedded microprocessor. This architecture provides a high performance low latency offload engine for both trasmit and receive side of data transactions: preliminary results are encouraging, showing 50% of bandwidth increase for large packet size transfers. In this paper we describe the APEnet+ architecture, detailing the hardware implementation and discuss the impact of such RDMA specialized hardware on host interface latency and bandwidth.

  2. Multisensor fusion for 3-D defect characterization using wavelet basis function neural networks

    NASA Astrophysics Data System (ADS)

    Lim, Jaein; Udpa, Satish S.; Udpa, Lalita; Afzal, Muhammad

    2001-04-01

    The primary objective of multi-sensor data fusion, which offers both quantitative and qualitative benefits, has the ability to draw inferences that may not be feasible with data from a single sensor alone. In this paper, data from two sets of sensors are fused to estimate the defect profile from magnetic flux leakage (MFL) inspection data. The two sensors measure the axial and circumferential components of the MFL. Data is fused at the signal level. If the flux is oriented axially, the samples of the axial signal are measured along a direction parallel to the flaw, while the circumferential signal is measured in a direction that is perpendicular to the flaw. The two signals are combined as the real and imaginary components of a complex valued signal. Signals from an array of sensors are arranged in contiguous rows to obtain a complex valued image. A boundary extraction algorithm is used to extract the defect areas in the image. Signals from the defect regions are then processed to minimize noise and the effects of lift-off. Finally, a wavelet basis function (WBF) neural network is employed to map the complex valued image appropriately to obtain the geometrical profile of the defect. The feasibility of the approach was evaluated using the data obtained from the MFL inspection of natural gas transmission pipelines. Results show the effectiveness of the approach.

  3. Applications of neural networks to landmark detection in 3-D surface data

    NASA Astrophysics Data System (ADS)

    Arndt, Craig M.

    1992-09-01

    The problem of identifying key landmarks in 3-dimensional surface data is of considerable interest in solving a number of difficult real-world tasks, including object recognition and image processing. The specific problem that we address in this research is to identify the specific landmarks (anatomical) in human surface data. This is a complex task, currently performed visually by an expert human operator. In order to replace these human operators and increase reliability of the data acquisition, we need to develop a computer algorithm which will utilize the interrelations between the 3-dimensional data to identify the landmarks of interest. The current presentation describes a method for designing, implementing, training, and testing a custom architecture neural network which will perform the landmark identification task. We discuss the performance of the net in relationship to human performance on the same task and how this net has been integrated with other AI and traditional programming methods to produce a powerful analysis tool for computer anthropometry.

  4. Engineering of a Biomimetic Pericyte-Covered 3D Microvascular Network

    PubMed Central

    Kim, Sudong; Jo, Dong Hyun; Kim, Jeong Hun; Jeon, Noo Li

    2015-01-01

    Pericytes enveloping the endothelium play an important role in the physiology and pathology of microvessels, especially in vessel maturation and stabilization. However, our understanding of fundamental pericyte biology is limited by the lack of a robust in vitro model system that allows researchers to evaluate the interactions among multiple cell types in perfusable blood vessels. The present work describes a microfluidic platform that can be used to investigate interactions between pericytes and endothelial cells (ECs) during the sprouting, growth, and maturation steps of neovessel formation. A mixture of ECs and pericytes was attached to the side of a pre-patterned three dimensional fibrin matrix and allowed to sprout across the matrix. The effects of intact coverage and EC maturation by the pericytes on the perfused EC network were confirmed using a confocal microscope. Compared with EC monoculture conditions, EC-pericyte co-cultured vessels showed a significant reduction in diameter, increased numbers of junctions and branches and decreased permeability. In response to biochemical factors, ECs and pericytes in the platform showed the similar features with previous reports from in vivo experiments, thus reflect various pathophysiological conditions of in vivo microvessels. Taken together, these results support the physiological relevancy of our three-dimensional microfluidic culture system but also that the system can be used to screen drug effect on EC-pericyte biology. PMID:26204526

  5. Pore network quantification of sandstones under experimental CO2 injection using image analysis

    NASA Astrophysics Data System (ADS)

    Berrezueta, Edgar; González-Menéndez, Luís; Ordóñez-Casado, Berta; Olaya, Peter

    2015-04-01

    Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. Our case study is focused on the application of these techniques to study the evolution of rock pore network subjected to super critical CO2-injection. We have proposed a Digital Image Analysis (DIA) protocol that guarantees measurement reproducibility and reliability. This can be summarized in the following stages: (i) detailed description of mineralogy and texture (before and after CO2-injection) by optical and scanning electron microscopy (SEM) techniques using thin sections; (ii) adjustment and calibration of DIA tools; (iii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers); (iv) study and quantification by DIA that allow (a) identification and isolation of pixels that belong to the same category: minerals vs. pores in each sample and (b) measurement of changes in pore network, after the samples have been exposed to new conditions (in our case: SC-CO2-injection). Finally, interpretation of the petrography and the measured data by an automated approach were done. In our applied study, the DIA results highlight the changes observed by SEM and microscopic techniques, which consisted in a porosity increase when CO2 treatment occurs. Other additional changes were minor: variations in the roughness and roundness of pore edges, and pore aspect ratio, shown in the bigger pore population. Additionally, statistic tests of pore parameters measured were applied to verify that the differences observed between samples before and after CO2-injection were significant.

  6. Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement.

    PubMed

    Zeng, Xiaoliang; Yao, Yimin; Gong, Zhengyu; Wang, Fangfang; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-12-01

    Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates. PMID:26479262

  7. Bone canalicular network segmentation in 3D nano-CT images through geodesic voting and image tessellation

    NASA Astrophysics Data System (ADS)

    Zuluaga, Maria A.; Orkisz, Maciej; Dong, Pei; Pacureanu, Alexandra; Gouttenoire, Pierre-Jean; Peyrin, Françoise

    2014-05-01

    Recent studies emphasized the role of the bone lacuno-canalicular network (LCN) in the understanding of bone diseases such as osteoporosis. However, suitable methods to investigate this structure are lacking. The aim of this paper is to introduce a methodology to segment the LCN from three-dimensional (3D) synchrotron radiation nano-CT images. Segmentation of such structures is challenging due to several factors such as limited contrast and signal-to-noise ratio, partial volume effects and huge number of data that needs to be processed, which restrains user interaction. We use an approach based on minimum-cost paths and geodesic voting, for which we propose a fully automatic initialization scheme based on a tessellation of the image domain. The centroids of pre-segmented lacunæ are used as Voronoi-tessellation seeds and as start-points of a fast-marching front propagation, whereas the end-points are distributed in the vicinity of each Voronoi-region boundary. This initialization scheme was devised to cope with complex biological structures involving cells interconnected by multiple thread-like, branching processes, while the seminal geodesic-voting method only copes with tree-like structures. Our method has been assessed quantitatively on phantom data and qualitatively on real datasets, demonstrating its feasibility. To the best of our knowledge, presented 3D renderings of lacunæ interconnected by their canaliculi were achieved for the first time.

  8. Bone canalicular network segmentation in 3D nano-CT images through geodesic voting and image tessellation.

    PubMed

    Zuluaga, Maria A; Orkisz, Maciej; Dong, Pei; Pacureanu, Alexandra; Gouttenoire, Pierre-Jean; Peyrin, Françoise

    2014-05-01

    Recent studies emphasized the role of the bone lacuno-canalicular network (LCN) in the understanding of bone diseases such as osteoporosis. However, suitable methods to investigate this structure are lacking. The aim of this paper is to introduce a methodology to segment the LCN from three-dimensional (3D) synchrotron radiation nano-CT images. Segmentation of such structures is challenging due to several factors such as limited contrast and signal-to-noise ratio, partial volume effects and huge number of data that needs to be processed, which restrains user interaction. We use an approach based on minimum-cost paths and geodesic voting, for which we propose a fully automatic initialization scheme based on a tessellation of the image domain. The centroids of pre-segmented lacunæ are used as Voronoi-tessellation seeds and as start-points of a fast-marching front propagation, whereas the end-points are distributed in the vicinity of each Voronoi-region boundary. This initialization scheme was devised to cope with complex biological structures involving cells interconnected by multiple thread-like, branching processes, while the seminal geodesic-voting method only copes with tree-like structures. Our method has been assessed quantitatively on phantom data and qualitatively on real datasets, demonstrating its feasibility. To the best of our knowledge, presented 3D renderings of lacunæ interconnected by their canaliculi were achieved for the first time. PMID:24710691

  9. 3D morphometry of valley networks on Mars from HRSC/MEX DEMs: Implications for climatic evolution through time

    NASA Astrophysics Data System (ADS)

    Ansan, V.; Mangold, N.

    2013-09-01

    valley networks have been identified mainly in the Noachian heavily cratered uplands. Eight dense branching valley networks were studied in Noachian terrains of Huygens, Newcomb and Kepler craters, south Tyrrhena Terra, and Thaumasia, in Hesperian terrains of Echus Plateau and west Eberswalde craters, and in Amazonian terrains of Alba Patera, using images and digital elevation models from the Mars Express High Resolution Stereo Camera to determine 2D and 3D morphometric parameters. Extracted geomorphic parameters show similar geometry to terrestrial valleys: drainage densities, organization from bifurcation ratios and lengths ratios, Hack exponent consistent with terrestrial values of ~0.6, and progressive deepening of valleys with increasing Strahler order. In addition, statistics on valley depths indicate a deeper incision of Noachian valleys compared to younger post-Noachian valleys (<25 m for Amazonian ones compared to >100 m for Noachian ones), showing a strong difference in fluvial erosion. These characteristics show that dense Martian valley networks formed by overland flows in relation to a global atmospheric water cycle in Noachian epoch and confirm that the later stages of activity may be related to shorter duration of activity, distinct climatic conditions, and/or regional processes, or conditions.

  10. Nanoparticles and 3D sponge-like porous networks of manganese oxides and their microwave absorption properties.

    PubMed

    Yan, D; Cheng, S; Zhuo, R F; Chen, J T; Feng, J J; Feng, H T; Li, H J; Wu, Z G; Wang, J; Yan, P X

    2009-03-11

    Hydrohausmannite nanoparticles (approximately 10 nm) were prepared by the hydrothermal method at 100 degrees C for 72 h. Subsequent annealing was done in air at 400 degrees C and 800 degrees C for 10 h, Mn(3)O(4) nanoparticles (approximately 25 nm) and 3D Mn(2)O(3) porous networks were obtained, respectively. The products were characterized by XRD, TEM, SAED and FESEM. Time-dependent experiments were carried out to exhibit the formation process of the Mn(2)O(3) networks. Their microwave absorption properties were investigated by mixing the product and paraffin wax with 50 vol%. The Mn(3)O(4) nanoparticles possess excellent microwave absorbing properties with the minimum reflection loss of -27.1 dB at 3.1 GHz. In contrast, the Mn(2)O(3) networks show the weakest absorption of all samples. The absorption becomes weaker with the annealing time increasing at 800 degrees C. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism was discussed in detail. PMID:19417534

  11. Mixed-scale channel networks including Kingfisher-beak-shaped 3D microfunnels for efficient single particle entrapment

    NASA Astrophysics Data System (ADS)

    Lee, Yunjeong; Lim, Yeongjin; Shin, Heungjoo

    2016-06-01

    Reproducible research results for nanofluidics and their applications require viable fabrication technologies to produce nanochannels integrated with microchannels that can guide fluid flow and analytes into/out of the nanochannels. We present the simple fabrication of mixed-scale polydimethylsiloxane (PDMS) channel networks consisting of nanochannels and microchannels via a single molding process using a monolithic mixed-scale carbon mold. The monolithic carbon mold is fabricated by pyrolyzing a polymer mold patterned by photolithography. During pyrolysis, the polymer mold shrinks by ~90%, which enables nanosized carbon molds to be produced without a complex nanofabrication process. Because of the good adhesion between the polymer mold and the Si substrate, non-uniform volume reduction occurs during pyrolysis resulting in the formation of curved carbon mold side walls. These curved side walls and the relatively low surface energy of the mold provide efficient demolding of the PDMS channel networks. In addition, the trigonal prismatic shape of the polymer is converted into to a Kingfisher-beak-shaped carbon structure due to the non-uniform volume reduction. The transformation of this mold architecture produces a PDMS Kingfisher-beak-shaped 3D microfunnel that connects the microchannel and the nanochannel smoothly. The smooth reduction in the cross-sectional area of the 3D microfunnels enables efficient single microparticle trapping at the nanochannel entrance; this is beneficial for studies of cell transfection.Reproducible research results for nanofluidics and their applications require viable fabrication technologies to produce nanochannels integrated with microchannels that can guide fluid flow and analytes into/out of the nanochannels. We present the simple fabrication of mixed-scale polydimethylsiloxane (PDMS) channel networks consisting of nanochannels and microchannels via a single molding process using a monolithic mixed-scale carbon mold. The monolithic

  12. Efficient 3D conducting networks built by graphene sheets and carbon nanoparticles for high-performance silicon anode.

    PubMed

    Zhou, Xiaosi; Yin, Ya-Xia; Cao, An-Min; Wan, Li-Jun; Guo, Yu-Guo

    2012-05-01

    The utilization of silicon particles as anode materials for lithium-ion batteries is hindered by their low intrinsic electric conductivity and large volume changes during cycling. Here we report a novel Si nanoparticle-carbon nanoparticle/graphene composite, in which the addition of carbon nanoparticles can effectively alleviate the aggregation of Si nanoparticles by separating them from each other, and help graphene sheets build efficient 3D conducting networks for Si nanoparticles. Such Si-C/G composite shows much improved electrochemical properties in terms of specific capacity and cycling performance (ca. 1521 mA h g(-1) at 0.2 C after 200 cycles), as well as a favorable high-rate capability. PMID:22563769

  13. Mesoporous Co3O4 sheets/3D graphene networks nanohybrids for high-performance sodium-ion battery anode

    NASA Astrophysics Data System (ADS)

    Liu, Yanguo; Cheng, Zhiying; Sun, Hongyu; Arandiyan, Hamidreza; Li, Jinpeng; Ahmad, Mashkoor

    2015-01-01

    Co3O4 mesoporous nanosheets/three-dimensional graphene networks (Co3O4 MNSs/3DGNs) nanohybrids have been successfully synthesized and investigated as anode materials for sodium ion batteries (SIBs). Microstructure characterizations have been performed to confirm the 3DGNs and Co3O4 MNSs nanostructures. It has been found that the present Co3O4 MNSs/3DGNs nanohybrids exhibit better SIB performance with enhanced reversible capacity, good cycle performance and rate capability as compared to Co3O4 MNSs and Co3O4 nanoparticles. The improved electrochemical performance is considered due to the mesoporous nature of the products, the addition of 3DGNs, 3D assembled hierarchical architecture and decrease in volume expansion during cycling. Thus, SIB is considered as a low cost alternative to LIBs for large-scale electric storage applications.

  14. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization

    PubMed Central

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g−1 at 1.2 V in 500 mg l−1 NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  15. Piezoresistive Sensor with High Elasticity Based on 3D Hybrid Network of Sponge@CNTs@Ag NPs.

    PubMed

    Zhang, Hui; Liu, Nishuang; Shi, Yuling; Liu, Weijie; Yue, Yang; Wang, Siliang; Ma, Yanan; Wen, Li; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua

    2016-08-31

    Pressure sensors with high elasticity are in great demand for the realization of intelligent sensing, but there is a need to develope a simple, inexpensive, and scalable method for the manufacture of the sensors. Here, we reported an efficient, simple, facile, and repeatable "dipping and coating" process to manufacture a piezoresistive sensor with high elasticity, based on homogeneous 3D hybrid network of carbon nanotubes@silver nanoparticles (CNTs@Ag NPs) anchored on a skeleton sponge. Highly elastic, sensitive, and wearable sensors are obtained using the porous structure of sponge and the synergy effect of CNTs/Ag NPs. Our sensor was also tested for over 2000 compression-release cycles, exhibiting excellent elasticity and cycling stability. Sensors with high performance and a simple fabrication process are promising devices for commercial production in various electronic devices, for example, sport performance monitoring and man-machine interfaces. PMID:27482721

  16. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization.

    PubMed

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g(-1) at 1.2 V in 500 mg l(-1) NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  17. Hybrid nickel manganese oxide nanosheet-3D metallic dendrite percolation network electrodes for high-rate electrochemical energy storage

    NASA Astrophysics Data System (ADS)

    Nguyen, Tuyen; Eugénio, Sónia; Boudard, Michel; Rapenne, Laetitia; Carmezim, M. João; Silva, Teresa M.; Montemor, M. Fátima

    2015-07-01

    This work reports the fabrication, by electrodeposition and post-thermal annealing, of hybrid electrodes for high rate electrochemical energy storage composed of nickel manganese oxide (Ni0.86Mn0.14O) nanosheets over 3D open porous dendritic NiCu foams. The hybrid electrodes are made of two different percolation networks of nanosheets and dendrites, and exhibit a specific capacitance value of 848 F g-1 at 1 A g-1. The electrochemical tests revealed that the electrodes display an excellent rate capability, characterized by capacitance retention of approximately 83% when the applied current density increases from 1 A g-1 to 20 A g-1. The electrodes also evidenced high charge-discharge cycling stability, which attained 103% after 1000 cycles.

  18. Tetrapeptide-coumarin conjugate 3D networks based on hydrogen-bonded charge transfer complexes: gel formation and dye release.

    PubMed

    Guo, Zongxia; Gong, Ruiying; Jiang, Yi; Wan, Xiaobo

    2015-08-14

    Oligopeptide-based derivatives are important synthons for bio-based functional materials. In this article, a Gly-(L-Val)-Gly-(L-Val)-coumarin (GVGV-Cou) conjugate was synthesized, which forms 3D networks in ethanol. The gel nanostructures were characterized by UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), SEM and TEM. It is suggested that the formation of charge transfer (CT) complexes between the coumarin moieties is the main driving force for the gel formation. The capability of the gel to encapsulate and release dyes was explored. Both Congo Red (CR) and Methylene Blue (MB) can be trapped in the CT gel matrix and released over time. The present gel might be used as a functional soft material for guest encapsulation and release. PMID:26138931

  19. The Derivation of Fault Volumetric Properties from 3D Trace Maps Using Outcrop Constrained Discrete Fracture Network Models

    NASA Astrophysics Data System (ADS)

    Hodgetts, David; Seers, Thomas

    2015-04-01

    -deterministic, outcrop constrained discrete fracture network modeling code to derive volumetric fault intensity measures (fault area per unit volume / fault volume per unit volume). Producing per-vertex measures of volumetric intensity; our method captures the spatial variability in 3D fault density across a surveyed outcrop, enabling first order controls to be probed. We demonstrate our approach on pervasively faulted exposures of a Permian aged reservoir analogue from the Vale of Eden Basin, UK.

  20. 3-D components of a biological neural network visualized in computer generated imagery. II - Macular neural network organization

    NASA Technical Reports Server (NTRS)

    Ross, Muriel D.; Meyer, Glenn; Lam, Tony; Cutler, Lynn; Vaziri, Parshaw

    1990-01-01

    Computer-assisted reconstructions of small parts of the macular neural network show how the nerve terminals and receptive fields are organized in 3-dimensional space. This biological neural network is anatomically organized for parallel distributed processing of information. Processing appears to be more complex than in computer-based neural network, because spatiotemporal factors figure into synaptic weighting. Serial reconstruction data show anatomical arrangements which suggest that (1) assemblies of cells analyze and distribute information with inbuilt redundancy, to improve reliability; (2) feedforward/feedback loops provide the capacity for presynaptic modulation of output during processing; (3) constrained randomness in connectivities contributes to adaptability; and (4) local variations in network complexity permit differing analyses of incoming signals to take place simultaneously. The last inference suggests that there may be segregation of information flow to central stations subserving particular functions.

  1. A 2-D Pore-Network Model of the Drying of Single-Component Liquids in Porous Media

    SciTech Connect

    Yortsos, Yanic C.; Yiotis, A.G.; Stubos, A.K.; Boundovis, A.G.

    2000-01-20

    The drying of liquid-saturated porous media is typically approaching using macroscopic continuum models involving phenomenological coefficients. Insight on these coefficients can be obtained by a more fundamental study at the pore- and pore-network levels. In this report, a model based on pore-network representation of porous media that accounts for various process at the pore-scale is presented. These include mass transfer by advection and diffusion in the gas phase, viscous flow in liquid and gas phases and capillary effects at the gas-liquid menisci in the pore throats.

  2. Imaging of pore networks and related interfaces in soil systems by using high resolution X-ray micro-CT

    NASA Astrophysics Data System (ADS)

    Zacher, Gerhard; Eickhorst, Thilo; Schmidt, Hannes; Halisch, Matthias

    2016-04-01

    Today's high-resolution X-ray CT with its powerful tubes and great detail detectability lends itself naturally to geological and pedological applications. Those include the non-destructive interior examination and textural analysis of rock and soil samples and their permeability and porosity - to name only a few. Especially spatial distribution and geometry of pores, mineral phases and fractures are important for the evaluation of hydrologic and aeration properties in soils as well as for root development in the soil matrix. The possibility to visualize a whole soil aggregate or root tissue in a non-destructive way is undoubtedly the most valuable feature of this type of analysis and is a new area for routine application of high resolution X-ray micro-CT. The paper outlines recent developments in hard- and software requirements for high resolution CT. It highlights several pedological applications which were performed with the phoenix nanotom m, the first 180 kV nanofocus CT system tailored specifically for extremely high-resolution scans of variable sized samples with voxel-resolutions down to < 300 nm. In addition very good contrast resolution can be obtained as well which is necessary to distinguish biogenic material in soil aggregates amongst others. We will address visualization and quantification of porous networks in 3D in different environmental samples ranging from clastic sedimentary rock to soil cores and individual soil aggregates. As several processes and habitat functions are related to various pore sizes imaging of the intact soil matrix will be presented on different scales of interest - from the mm-scale representing the connectivity of macro-pores down to the micro-scale representing the space of microbial habitats. Therefore, soils were impregnated with resin and scanned via X-ray CT. Scans at higher resolution were obtained from sub-volumes cut from the entire resin impregnated block and from crop roots surrounded by rhizosphere soil. Within the

  3. Petrophysical and magnetic pore network anisotropy of some cretaceous sandstone from Tushka Basin, Egypt

    NASA Astrophysics Data System (ADS)

    Nabawy, Bassem S.; Rochette, Pierre; Géraud, Yves

    2009-04-01

    Pore magnetic fabric is a well-established technique for the determination of pore elongation and preferred directions for migration of the interstitial fluids. This study further exemplify this technique on a set of the Nubia sandstones through a comparison with the pore anisotropy obtained from measuring permeability in three orthogonal directions in a gaz permeameter. The Nubia sandstones are represented in Tushka area (South Egypt) by quartz arenite of large porosity (29-40 per cent) which was measured on thin sections parallel and perpendicular to the bedding plane and petrophysically by helium pycnometry and ferrofluid injection at 1 bar pressure. Petrographically, there is a detectable difference between the porosity values in the bedding plane and in the perpendicular direction indicating inhomogeneity in the pore space network distribution. The petrophysical studies indicate large porosity and permeability values with some differences between the helium and ferrofluid porosity due to presence of micro pore spaces not accessible for the ferrofluid molecules having relatively high diameters and injected at low pressure. An overall agreement is observed between the permeability anisotropy and the magnetic grain and pore fabrics (magnetic anisotropy measured before and after ferrofluid injection). The three fabrics are mainly dominated by a bedding parallel foliation. In a few cases maximum permeability appears to be perpendicular to bedding. Within the bedding plane, maximum pore elongation direction from ferrofluid injection is NNW for Adindan and Kesieba formations and NW for Abu Simbil Formation. The maximum pore elongation direction for Abu Ballas samples showed a direction fluctuating around the E-W direction, the main fault trends in Tushka area. The pore fabric of Abu Ballas formation seems therefore to be structurally controlled, while it would be originated from palaeocurrent directions in the other formations.

  4. Do you see what I hear: experiments in multi-channel sound and 3D visualization for network monitoring?

    NASA Astrophysics Data System (ADS)

    Ballora, Mark; Hall, David L.

    2010-04-01

    Detection of intrusions is a continuing problem in network security. Due to the large volumes of data recorded in Web server logs, analysis is typically forensic, taking place only after a problem has occurred. This paper describes a novel method of representing Web log information through multi-channel sound, while simultaneously visualizing network activity using a 3-D immersive environment. We are exploring the detection of intrusion signatures and patterns, utilizing human aural and visual pattern recognition ability to detect intrusions as they occur. IP addresses and return codes are mapped to an informative and unobtrusive listening environment to act as a situational sound track of Web traffic. Web log data is parsed and formatted using Python, then read as a data array by the synthesis language SuperCollider [1], which renders it as a sonification. This can be done either for the study of pre-existing data sets or in monitoring Web traffic in real time. Components rendered aurally include IP address, geographical information, and server Return Codes. Users can interact with the data, speeding or slowing the speed of representation (for pre-existing data sets) or "mixing" sound components to optimize intelligibility for tracking suspicious activity.

  5. Tooth periodontal ligament: Direct 3D microCT visualization of the collagen network and how the network changes when the tooth is loaded.

    PubMed

    Naveh, Gili R S; Brumfeld, Vlad; Shahar, Ron; Weiner, Steve

    2013-02-01

    The periodontal ligament (PDL), a soft tissue connecting the tooth and the bone, is essential for tooth movement, bone remodeling and force dissipation. A collagenous network that connects the tooth root surface to the alveolar jaw bone is one of the major components of the PDL. The organization of the collagenous component and how it changes under load is still poorly understood. Here using a state-of-the-art custom-made loading apparatus and a humidified environment inside a microCT, we visualize the PDL collagenous network of a fresh rat molar in 3D at 1 μm voxel size without any fixation or contrasting agents. We demonstrate that the PDL collagen network is organized in sheets. The spaces between sheets vary thus creating dense and sparse networks. Upon vertical loading, the sheets in both networks are stretched into well aligned arrays. The sparse network is located mainly in areas which undergo compressive loading as the tooth moves towards the bone, whereas the dense network functions mostly in tension as the tooth moves further from the bone. This new visualization method can be used to study other non-mineralized or partially mineralized tissues, and in particular those that are subjected to mechanical loads. The method will also be valuable for characterizing diseased tissues, as well as better understanding the phenotypic expressions of genetic mutants. PMID:23110851

  6. Using Microfluidics for Visualisation of Displacement Mechanisms on Pore Network Models

    NASA Astrophysics Data System (ADS)

    Gerami Kaviri Nejad, A.; Mostaghimi, P.; Armstrong, R. T.; Rafeie, M.; Ebrahimi Warkiani, M.

    2015-12-01

    We use microfluidic methods for studying displacement mechanisms of immiscible fluids including drainage and imbibition in porous media at the pore scale. We use soft lithography method to make 4' diameter silicon wafer to be used as a mould of our designs. We have fabricated a range of microfluidic chips based on a range of patterns including pore junction with unequal throats, junction of throats with different coordination numbers, and junction of tortuous throats. We also fabricate more complex networks as a combination of the mentioned simple patterns. Decane and water are used as the wetting and non-wetting phases, respectively. Using high-resolution microscopy, we visualise the displacement processes and the movement of the interface between two fluids at different saturations. We initially test to micromodel chip for modelling drainage into a pore junction and compare our results with the prediction by the Young-Laplace equations. Then we focus on the sequence of pore filling and effects of pore space geometry, tortuosity and the injection rate. We use plasma treating to vary the contact angle and then study the effects of wettability on interface movement. Using accurate pump and pressure controller, we measure pressure drop across the micromodels at different time. By image processing of fluids distribution in the microfluidic chip, saturation of both phases can be estimated. Then, we plot relative permeability versus saturation curves for different pore space geometries. Our results can be used for validation of numerical two phase flow simulation and also we provide novel suggestions for modifying the equations of motion in pore network models.

  7. Determination of 3D surface displacement rates in the Upper Rhine Graben based on GURN (GNSS Upper Rhine Graben Network)

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Knöpfler, A.; Masson, F.; Ulrich, P.; Heck, B.

    2012-04-01

    regional network GURN actually consists of approx. 80 permanently operating GNSS sites of different data providers in Germany, France and Switzerland. The first work steps in the context of GURN were dominated by a detailed analysis of the GNSS data base (e.g., instrumental change artefacts). This analysis included a comparison of the working group related results (EOST, GIK), where different software packages and data handling strategies were used to derive 3D coordinate time series as basis for the determination of a 3D surface displacement field. Due to very small expected velocities in the URG region, the recent GURN focus is on the reliable derivation of site velocities, therefore effects of datum realisation have to be handled with care. The presentation gives an insight into the joint venture GURN focussing on recent results (e.g., 3D surface velocity field).

  8. Templated assembly of BiFeO3 nanocrystals into 3D mesoporous networks for catalytic applications

    NASA Astrophysics Data System (ADS)

    Papadas, I. T.; Subrahmanyam, K. S.; Kanatzidis, M. G.; Armatas, G. S.

    2015-03-01

    The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4.The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4. Electronic supplementary information (ESI

  9. The value of inclined coreholes for characterizing the geometry of 3-D fracture networks in bedrock aquifers

    NASA Astrophysics Data System (ADS)

    Munn, Jonathan; Parker, Beth

    2013-04-01

    In bedrock aquifers where matrix permeability is low, the nature and distribution of the fracture network has a strong impact on the transport and fate of contaminants. Accurate fracture characterization is therefore essential to fully understand the flow system and to predict contaminant migration. Powerful DFN models exist, yet the limitation is often on obtaining field data of sufficient quality to use as input parameters. One major contributing factor is the common practice of using only vertical coreholes to characterize bedrock aquifers. This can lead to datasets that are significantly biased toward fractures perpendicular to the corehole and are therefore not well suited for three-dimensional (3-D) fracture geometry characterization. This bias is particularly pronounced in flat-lying sedimentary strata where fracture networks are typically comprised of flat-lying bedding parallel fractures and vertical, or near vertical joints. An examination of such bias was conducted at a contaminated site in Guelph, Ontario, Canada, in a Silurian dolostone aquifer. Three inclined coreholes plunging 60 degrees with varying azimuths were drilled between 2010 and 2012 to supplement existing data from eleven vertical coreholes from previous investigations. Depth discrete datasets were collected in the coreholes including lithological and fracture logs from rock core, downhole geophysical surveys (e.g, acoustic televiewer, formation conductivity, temperature, natural gamma), and hydraulic testing including the first use of flexible liner profiling in inclined coreholes. These datasets were integrated to provide estimates of fracture frequency, orientation and aperture distributions and to estimate values of bulk effective fracture porosity. Orientation analysis revealed three dominant fracture sets on site that vary in intensity through mechanical layers. These sets consist of a horizontal, bedding-plane set with an average spacing of 0.3m, and two high-angle sets, NE-SW and

  10. NiO nanoarrays of a few atoms thickness on 3D nickel network for enhanced pseudocapacitive electrode applications

    NASA Astrophysics Data System (ADS)

    Senthilkumar, Velusamy; Kadumudi, Firoz Babu; Ho, Nhu Thuy; Kim, Ji-Woong; Park, Sungkyun; Bae, Jong-Seong; Choi, Won Mook; Cho, Shinuk; Kim, Yong Soo

    2016-01-01

    The present work focuses on the development of template-free mesoporous NiO nanoarrays with large surface area grown on 3D nickel foam networks by a seed mediated aqueous chemical growth technique and subsequent annealing process. The resultant binder-free, well-aligned and vertically grown NiO nanoarrays exhibits a micron-sized planar structure as well as an ultrathin thickness (˜7 nm). The unique surface and electronic structure facilitates surface-dependent electrochemical reaction processes with no dead volume. They deliver a high capacitance of 2065 F g-1 at a current density of 16 A g-1 as a three electrode system. A specific capacitance of 1247 F g-1 is maintained at a higher current rate of 70 A g-1 with 88.9% retention after 5000 cycles. Finally, in a solid-state asymmetric supercapacitor configuration using NiO//activated carbon, the device delivers an enhanced supercapacitive performance, with an energy density of 43.5 Wh kg-1 and power density of 2.1 kW kg-1. Thus, the current research paves the way for the use of NiO nanoarrays as an electrode material for practical supercapacitor devices with higher cycling retention and rate capacity.

  11. Flexible, solid-state, ion-conducting membrane with 3D garnet nanofiber networks for lithium batteries.

    PubMed

    Fu, Kun Kelvin; Gong, Yunhui; Dai, Jiaqi; Gong, Amy; Han, Xiaogang; Yao, Yonggang; Wang, Chengwei; Wang, Yibo; Chen, Yanan; Yan, Chaoyi; Li, Yiju; Wachsman, Eric D; Hu, Liangbing

    2016-06-28

    Beyond state-of-the-art lithium-ion battery (LIB) technology with metallic lithium anodes to replace conventional ion intercalation anode materials is highly desirable because of lithium's highest specific capacity (3,860 mA/g) and lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode). In this work, we report for the first time, to our knowledge, a 3D lithium-ion-conducting ceramic network based on garnet-type Li6.4La3Zr2Al0.2O12 (LLZO) lithium-ion conductor to provide continuous Li(+) transfer channels in a polyethylene oxide (PEO)-based composite. This composite structure further provides structural reinforcement to enhance the mechanical properties of the polymer matrix. The flexible solid-state electrolyte composite membrane exhibited an ionic conductivity of 2.5 × 10(-4) S/cm at room temperature. The membrane can effectively block dendrites in a symmetric Li | electrolyte | Li cell during repeated lithium stripping/plating at room temperature, with a current density of 0.2 mA/cm(2) for around 500 h and a current density of 0.5 mA/cm(2) for over 300 h. These results provide an all solid ion-conducting membrane that can be applied to flexible LIBs and other electrochemical energy storage systems, such as lithium-sulfur batteries. PMID:27307440

  12. A series of rare earth complexes with novel non-interpenetrating 3D networks: synthesis, structures, magnetic and optical properties.

    PubMed

    Wei, Xiao-Hua; Yang, Lin-Yan; Liao, Sheng-Yun; Zhang, Ming; Tian, Jin-Lei; Du, Pei-Yao; Gu, Wen; Liu, Xin

    2014-04-21

    A series of metal-organic framework {Ln(BCPBA)(H2O)}n {Ln = Nd (1), Sm (2), Eu (3), Tb (4), Dy (5)}; {[Ln(BCPBA)(H2O)](H2O)}n {Ln = Pr (6), Gd (7)} have been synthesized through the hydrothermal synthesis method. These compounds possess non-interpenetrating 3D networks with 10.1438 Å× 17.9149 Å rhombic channels along the [001] direction. The results of temperature-dependent magnetic susceptibility measurements indicate that compounds 4 and 7 exhibit Ln(III)Ln(III) antiferromagnetic interactions, while compound 5 exhibits Ln(III)Ln(III) ferromagnetic interactions. Frequency dependent out-of-phase signals were observed in alternating current (ac) magnetic susceptibility measurements which indicate that they have slow magnetic relaxation characteristics. The luminescent properties of 1, 2, 3, 4, and 5 are also discussed. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, compound 4 has longer fluorescence lifetime (τ1 = 400.0000 ms, τ2 = 1143.469 ms) and higher quantum yield (Φ = 42%) compared with other compounds. PMID:24572766

  13. The 3-D strain patterns in Turkey using geodetic velocity fields from the RTK-CORS (TR) network

    NASA Astrophysics Data System (ADS)

    Kutoglu, Hakan Senol; Toker, Mustafa; Mekik, Cetin

    2016-03-01

    This study presents our use of GPS data to obtain and quantify the full continuous strain tensor using a 3-D velocity field in Turkey. In this study, GPS velocities improve the estimation of short-term strain tensor fields for determining the seismic hazard of Turkey. The tensorial analysis presents different aspects of deformation, such as the normal and shear strains, including their directions, the compressional and extensional strains. This analysis is appropriate for the characterizing the state of the current seismic deformation. GPS velocity data from continuous measurements (2009-2012) to estimate deformations were processed using the GAMIT/GLOBK software. Using high-rate GPS data from permanent 146 GNSS stations (RTK-CORS-TR network), the strain distribution was determined and interpolated using a biharmonic spline technique. We show the strain field patterns within axial and plane form at several critical locations, and discuss these results within the context of the seismic and tectonic deformation of Turkey. We conclude that the knowledge of the crustal strain patterns provides important information on the location of the main faults and strain accumulation for the hazard assessment. The results show an agreement between the seismic and tectonic strains confirming that there are active crustal deformations in Turkey.

  14. Liver Tumor Segmentation from MR Images Using 3D Fast Marching Algorithm and Single Hidden Layer Feedforward Neural Network

    PubMed Central

    2016-01-01

    Objective. Our objective is to develop a computerized scheme for liver tumor segmentation in MR images. Materials and Methods. Our proposed scheme consists of four main stages. Firstly, the region of interest (ROI) image which contains the liver tumor region in the T1-weighted MR image series was extracted by using seed points. The noise in this ROI image was reduced and the boundaries were enhanced. A 3D fast marching algorithm was applied to generate the initial labeled regions which are considered as teacher regions. A single hidden layer feedforward neural network (SLFN), which was trained by a noniterative algorithm, was employed to classify the unlabeled voxels. Finally, the postprocessing stage was applied to extract and refine the liver tumor boundaries. The liver tumors determined by our scheme were compared with those manually traced by a radiologist, used as the “ground truth.” Results. The study was evaluated on two datasets of 25 tumors from 16 patients. The proposed scheme obtained the mean volumetric overlap error of 27.43% and the mean percentage volume error of 15.73%. The mean of the average surface distance, the root mean square surface distance, and the maximal surface distance were 0.58 mm, 1.20 mm, and 6.29 mm, respectively. PMID:27597960

  15. Liver Tumor Segmentation from MR Images Using 3D Fast Marching Algorithm and Single Hidden Layer Feedforward Neural Network.

    PubMed

    Le, Trong-Ngoc; Bao, Pham The; Huynh, Hieu Trung

    2016-01-01

    Objective. Our objective is to develop a computerized scheme for liver tumor segmentation in MR images. Materials and Methods. Our proposed scheme consists of four main stages. Firstly, the region of interest (ROI) image which contains the liver tumor region in the T1-weighted MR image series was extracted by using seed points. The noise in this ROI image was reduced and the boundaries were enhanced. A 3D fast marching algorithm was applied to generate the initial labeled regions which are considered as teacher regions. A single hidden layer feedforward neural network (SLFN), which was trained by a noniterative algorithm, was employed to classify the unlabeled voxels. Finally, the postprocessing stage was applied to extract and refine the liver tumor boundaries. The liver tumors determined by our scheme were compared with those manually traced by a radiologist, used as the "ground truth." Results. The study was evaluated on two datasets of 25 tumors from 16 patients. The proposed scheme obtained the mean volumetric overlap error of 27.43% and the mean percentage volume error of 15.73%. The mean of the average surface distance, the root mean square surface distance, and the maximal surface distance were 0.58 mm, 1.20 mm, and 6.29 mm, respectively. PMID:27597960

  16. Cataloguing Seismic Waveform Properties Recorded With a 3D Network in a Gold Mine in South Africa

    NASA Astrophysics Data System (ADS)

    Julia, J.; Nyblade, A. A.; Gok, R.; Walter, W. R.; Linzer, L.; Durrheim, R. J.; Dirks, P.

    2007-12-01

    The SAVUKA gold mine is located in the northwestern edge of the Witwatersrand basin, a Late Archean (3.07- 2.71~Ga) intracratonic basin in South Africa that hosts the largest known gold-uranium-pyrite ore deposits in the world. Seismic events related to the mine activity span several orders of magnitude through a variety of sources that include mine blasts, pillar collapses, and faulting events. These events are systematically recorded and catalogued through an in-mine, 3D seismic network consisting of 20, three-component, short-period stations with natural frequencies ranging between 4.5 and 28.0~Hz and deployed as deep as ~3.5 km. After 5 months of seismic monitoring of the mine, we have been able to assemble a database of over 6000 events spanning magnitudes in the -2.5 < ML < 4.4 range. The potential of this unique data set for characterizing the detailed seismic properties of the basin and studying source properties of non-double couple events is explored through simple, first-pass analysis on the recorded waveforms. Moreover, the in-mine network is complemented by a small array of 4 broadband stations interspaced ~10~km apart on the surface of the mine, and by a number of AfricaArray stations in South Africa and neighboring countries located at regional distances (50- 1000~km) from the mine. The largest mine-induced events are clearly recorded at distances as far away from the mine as 450~km and provide a unique opportunity for studying the regional propagation of seismic phases as well as the structure of the cratonic crust underlying the basin.

  17. 3D hierarchical MnO2 nanorod/welded Ag-nanowire-network composites for high-performance supercapacitor electrodes.

    PubMed

    Qiao, Zhensong; Yang, Xiaopeng; Yang, Shuhua; Zhang, Liqiang; Cao, Bingqiang

    2016-06-28

    3D MnO2 nanorod/welded Ag-nanowire-network supercapacitor electrodes were prepared. Welding treatment of the Ag nanowire-network leads to low resistance and long lifetime. Galvanostatic charge/discharge (GCD) induces an ever-lasting morphology changing from flower-like to honeycomb-like for MnO2, which manifests as increasing specific capacitance to 663.4 F g(-1) after 7000 GCD cycles. PMID:27263832

  18. Optical Image Analysis Applied to Pore Network Quantification of Sandstones Under Experimental CO2 Injection

    NASA Astrophysics Data System (ADS)

    Berrezueta, E.; González, L.; Ordóñez, B.; Luquot, L.; Quintana, L.; Gallastegui, G.; Martínez, R.; Olaya, P.; Breitner, D.

    2015-12-01

    This research aims to propose a protocol for pore network quantification in sandstones applying the Optical Image Analysis (OIA) procedure, which guarantees the measurement reproducibility and its reliability. Two geological formations of sandstone, located in Spain and potentially suitable for CO2 sequestration, were selected for this study: a) the Cretaceous Utrillas unit, at the base of the Cenozoic Duero Basin and b) a Triassic unit at the base of the Cenozoic Guadalquivir Basin. Sandstone samples were studied before and after the CO2 experimental injection using Optical and scanning electronic microscopy (SEM), while the quantification of petrographic changes was done with OIA. The first phase of the rersearch consisted on a detailed mineralogical and petrographic study of the sandstones (before and after CO2-injection), for which we observed thin sections. Later, the methodological and experimental processes of the investigation were focused on i) adjustment and calibration of OIA tools; ii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers), using 7 images of the same mineral scene (6 in crossed polarizer and 1 in parallel polarizer); and iii) automated identification and segmentation of pore in 2D mineral images, generating applications by executable macros. Finally, once the procedure protocols had been, the compiled data was interpreted through an automated approach and the qualitative petrography was carried out. The quantification of changes in the pore network through OIA (porosity increase ≈ 2.5%) has allowed corroborate the descriptions obtained by SEM and microscopic techniques, which consisted in an increase in the porosity when CO2 treatment occurs. Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. This research offers numerical

  19. Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

    SciTech Connect

    Liu, Haihu; Zhang, Yonghao; Valocchi, Albert J.

    2015-05-15

    Injection of anthropogenic carbon dioxide (CO{sub 2}) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO{sub 2} that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns, namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (S{sub nw}) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in S{sub nw}. In either pore networks, the specific interfacial length is linearly proportional to S{sub nw} during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on S{sub nw} for either favorable (M ≥ 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement.

  20. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes

    PubMed Central

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-01-01

    The single–crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment. PMID:25800933

  1. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-03-01

    The single-crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment.

  2. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes.

    PubMed

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-01-01

    The single-crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment. PMID:25800933

  3. Freeze-cast alumina pore networks: Effects of freezing conditions and dispersion medium

    SciTech Connect

    Miller, S. M.; Xiao, X.; Faber, K. T.

    2015-11-01

    Alumina ceramics were freeze-cast from water- and camphene-based slurries under varying freezing conditions and examined using X-ray computed tomography (XCT). Pore network characteristics, i.e., porosity, pore size, geometric surface area, and tortuosity, were measured from XCT reconstructions and the data were used to develop a model to predict feature size from processing conditions. Classical solidification theory was used to examine relationships between pore size, temperature gradients, and freezing front velocity. Freezing front velocity was subsequently predicted from casting conditions via the two-phase Stefan problem. Resulting models for water-based samples agreed with solidification-based theories predicting lamellar spacing of binary eutectic alloys, and models for camphene-based samples concurred with those for dendritic growth. Relationships between freezing conditions and geometric surface area were also modeled by considering the inverse relationship between pore size and surface area. Tortuosity was determined to be dependent primarily on the type of dispersion medium. (C) 2015 Elsevier Ltd. All rights reserved.

  4. Three 3D hybrid networks based on octamolybdates and different Cu I/Cu II-bis(triazole) motifs

    NASA Astrophysics Data System (ADS)

    Zhang, Chun-Jing; Pang, Hai-Jun; Tang, Qun; Wang, Hui-Yuan; Chen, Ya-Guang

    2010-12-01

    Three 3D compounds based on octamolybdate clusters and various Cu I/Cu II-bis(triazole) motifs, [Cu I2btb][ β-Mo 8O 26] 0.5 ( 1), [Cu I2btpe][ β-Mo 8O 26] 0.5 ( 2), and [Cu II(btpe) 2][ β-Mo 8O 26] 0.5 ( 3) [btb=1,4-bis(1,2,4-triazol-1-yl)butane, btpe=1,5-bis(1,2,4-triazol-1-yl)pentane], were isolated via tuning flexible ligand spacer length and metal coordination preferences. In 1, the copper(I)-btb motif is a one-dimensional (1D) chain which is further linked by hexadentate β-[Mo 8O 26] 4- clusters via coordinating to Cu I cations giving a 3D structure. In 2, the copper(I)-btpe motif exhibits a "stairs"-like [Cu I2btpe] 2+ sheet, and the tetradentate β-[Mo 8O 26] 4- clusters interact with two neighboring [Cu I2btpe] 2+ sheets constructing a 3D framework. In 3, the copper(II)-btpe motif possesses a novel (2D→3D) interdigitated structure, which is further connected by the tetradentate β-[Mo 8O 26] 4- clusters forming a 3D framework. The thermal stability and luminescent properties of 1- 3 are investigated in the solid state.

  5. Concerted motions networking pores and distant ferroxidase centers enable bacterioferritin function and iron traffic.

    PubMed

    Yao, Huili; Rui, Huan; Kumar, Ritesh; Eshelman, Kate; Lovell, Scott; Battaile, Kevin P; Im, Wonpil; Rivera, Mario

    2015-03-01

    X-ray crystallography, molecular dynamics (MD) simulations, and biochemistry were utilized to investigate the effect of introducing hydrophobic interactions in the 4-fold (N148L and Q151L) and B-pores (D34F) of Pseudomonas aeruginosa bacterioferritin B (BfrB) on BfrB function. The structures show only local structural perturbations and confirm the anticipated hydrophobic interactions. Surprisingly, structures obtained after soaking crystals in Fe2+-containing crystallization solution revealed that although iron loads into the ferroxidase centers of the mutants, the side chains of ferroxidase ligands E51 and H130 do not reorganize to bind the iron ions, as is seen in the wt BfrB structures. Similar experiments with a double mutant (C89S/K96C) prepared to introduce changes outside the pores show competent ferroxidase centers that function akin to those in wt BfrB. MD simulations comparing wt BfrB with the D34F and N148L mutants show that the mutants exhibit significantly reduced flexibility and reveal a network of concerted motions linking ferroxidase centers and 4-fold and B-pores, which are important for imparting ferroxidase centers in BfrB with the required flexibility to function efficiently. In agreement, the efficiency of Fe2+ oxidation and uptake of the 4-fold and B-pore mutants in solution is significantly compromised relative to wt or C89S/K96C BfrB. Finally, our structures show a large number of previously unknown iron binding sites in the interior cavity and B-pores of BfrB, which reveal in unprecedented detail conduits followed by iron and phosphate ions across the BfrB shell, as well as paths in the interior cavity that may facilitate nucleation of the iron phosphate mineral. PMID:25640193

  6. A Sequential Dynamic Bayesian Network for Pore Pressure Prediction and Quantification of Uncertainty.

    NASA Astrophysics Data System (ADS)

    Oughton, R. H.; Wooff, D. A.; Hobbs, R. W.; Swarbrick, R. E.

    2014-12-01

    Pore pressure prediction is vital when drilling a well, as unexpected overpressure can cause drilling challenges and uncontrolled hydrocarbon leakage. One cause of overpressure is when pore fluid is trapped during burial and takes on part of the lithostatic load. Predictions often use porosity-based techniques, such as the Eaton Ratio method and equivalent depth method. These rely on an idealised compaction trend and use a single wireline log as a proxy for porosity. Such methods do not account for the many sources of uncertainty, or for the multivariate nature of the system. We propose a sequential dynamic Bayesian network (SDBN) as a solution to these issues. The SDBN models the quantities in the system (such as pressures, porosity, lithology, wireline logs, fluid properties and so on) using conditional probability distributions to capture their joint behaviour. A compaction model is central to the SDBN, relating porosity to vertical effective stress, with uncertainty in the relationship, so that the logic is similar to that of the equivalent depth method. The probability distribution for porosity depends on VES and lithology, with much more uncertainty in sandstone-like rocks than in shales to reflect a general lack of understanding of sandstone compaction. The distributions of the wireline logs depend on porosity and lithology, along with other quantities, and so when they are observed the SDBN learns about porosity and lithology and in turn VES and pore pressure, using Bayes theorem. The probability distribution for each quantity in the SDBN is updated in light of any data, so that rather than giving a single-valued prediction for pore pressure, the SDBN gives a prediction with uncertainty that takes into account the whole system, knowledge and data. The dynamic nature of the SDBN enables it to use the bulk density to calculate total vertical stress, and to account for the dissipation of pore pressure. The vertical correlation in the SDBN means it is suited to

  7. A Novel 3D Fibril Force Assay Implicates Src in Tumor Cell Force Generation in Collagen Networks

    PubMed Central

    Polackwich, Robert J.; Koch, Daniel; Arevalo, Richard; Miermont, Anne M.; Jee, Kathleen J.; Lazar, John; Urbach, Jeffrey; Mueller, Susette C.; McAllister, Ryan G.

    2013-01-01

    New insight into the biomechanics of cancer cell motility in 3D extracellular matrix (ECM) environments would significantly enhance our understanding of aggressive cancers and help identify new targets for intervention. While several methods for measuring the forces involved in cell-matrix interactions have been developed, previous to this study none have been able to measure forces in a fibrillar environment. We have developed a novel assay for simultaneously measuring cell mechanotransduction and motility in 3D fibrillar environments. The assay consists of a controlled-density fibrillar collagen gel atop a controlled-stiffness polyacrylamide (PAA) surface. Forces generated by living cells and their migration in the 3D collagen gel were measured with the 3D motion of tracer beads within the PAA layer. Here, this 3D fibril force assay is used to study the role of the invasion-associated protein kinase Src in mechanotransduction and motility. Src expression and activation are linked with proliferation, invasion, and metastasis, and have been shown to be required in 2D for invadopodia membranes to direct and mediate invasion. Breast cancer cell line MDA-MD-231 was stably transfected with GFP-tagged constitutively active Src or wild-type Src. In 3D fibrillar collagen matrices we found that, relative to wild-type Src, constitutively active Src: 1) increased the strength of cell-induced forces on the ECM, 2) did not significantly change migration speed, and 3) increased both the duration and the length, but not the number, of long membrane protrusions. Taken together, these results support the hypothesis that Src controls invasion by controlling the ability of the cell to form long lasting cellular protrusions to enable penetration through tissue barriers, in addition to its role in promoting invadopodia matrix-degrading activity. PMID:23536784

  8. A Distributed Fiber Optic Sensor Network for Online 3-D Temperature and Neutron Fluence Mapping in a VHTR Environment

    SciTech Connect

    Tsvetkov, Pavel; Dickerson, Bryan; French, Joseph; McEachern, Donald; Ougouag, Abderrafi

    2014-04-30

    Robust sensing technologies allowing for 3D in-core performance monitoring in real time are of paramount importance for already established LWRs to enhance their reliability and availability per year, and therefore, to further facilitate their economic competitiveness via predictive assessment of the in-core conditions.

  9. Tight dual models of pore spaces

    NASA Astrophysics Data System (ADS)

    Glantz, Roland; Hilpert, Markus

    2008-05-01

    The pore throats in a porous medium control permeability, drainage, and straining through their pore scale geometry and through the way they are connected via pore bodies on the macroscale. Likewise, imbibition is controlled through the geometry of the pore bodies (pore scale) and through the way the pore bodies are connected via pore throats on the macroscale. In an effort to account for both scales at the same time we recently introduced an image-based model for pore spaces that consists of two parts related by duality: (1) a decomposition of a polyhedral pore space into polyhedral pore bodies separated by polygonal pore throats and (2) a polygonal pore network that is homotopy equivalent to the pore space. In this paper we stick to the dual concept while amending the definition of the pore throats and, as a consequence, the other elements of the dual model. Formerly, the pore throats consisted of single two-dimensional Delaunay cells, while they now usually consist of more than one two-dimensional Delaunay cell and extend all the way into the narrowing ends of the pore channel cross sections. This is the first reason for naming the amended dual model "tight". The second reason is that the formation of the pore throats is now guided by an objective function that always attains its global optimum (tight optimization). At the end of the paper we report on simulations of drainage performed on tight dual models derived from simulated sphere packings and 3D gray-level images. The C-code for the generation of the tight dual model and the simulation of drainage is publicly available at https://jshare.johnshopkins.edu/mhilper1/public_html/tdm.html.

  10. Pore Network Simulation to Develop Electrical Petrophysical Relations in the Presence of Mass Transfer

    NASA Astrophysics Data System (ADS)

    Day-Lewis, F. D.; Haggerty, R.; Singha, K.; Binley, A.; Swanson, R. D.; Clifford, J.; Lane, J. W.; Ward, A. L.; Johnson, T. J.

    2011-12-01

    In both field and laboratory settings, time-lapse electrical measurements have indicated rate-limited mass transfer of ionic tracer between mobile and immobile (or less mobile) domains in porous media over a range of flow rates and time scales. In previous work, a simple bicontinuum extension of Archie's Law was used to relate direct-current bulk conductivity and fluid conductivity assuming that the mobile and immobile domains contribute as conductors in parallel with weights given by porosity fraction; however, other petrophysical models may account for the effect of internal connectivity of each domain on its relative contribution to bulk conductivity. Additional work is required to (1) evaluate the bicontinuum Archie formulation relative to these other models for bulk conductivity of multiphase (i.e., multidomain) media with application to mass-transfer problems, and (2) characterize the geoelectrical signature of mass transfer for porous media with different pore geometries and electrical properties. To address this long standing problem, we developed a coupled fluid flow, electrical conduction, and solute transport simulator for two-dimensional pore networks. The pore space is modeled as a pipe lattice where pipes are square in cross section with widths drawn from random distributions. Pipe conductances for the fluid flow problem are assigned according to Hagen-Pouseuille flow, and the conservation problem is solved. Alternative to computationally intensive simulation of transient advective-dispersive transport, we adopt a more efficient but approximate two-step approach. First, we find the zeroth and first temporal moments throughout the network by solving sequentially two steady-state transport problems; from these results we calculate mean arrival time for each node in the network. Second, we convert the calculated mean arrival times to mass-transfer rates for input to a semi-analytical multi-rate mass transfer model to simulate gross transport through a

  11. A pore-network model for foam formation and propagation in porous media

    SciTech Connect

    Kharabaf, H.; Yortsos, Y.C.

    1996-12-31

    We present a pore-network model, based on a pores-and-throats representation of the porous medium, to simulate the generation and mobilization of foams in porous media. The model allows for various parameters or processes, empirically treated in current models, to be quantified and interpreted. Contrary to previous works, we also consider a dynamic (invasion) in addition to a static process. We focus on the properties of the displacement, the onset of foam flow and mobilization, the foam texture and the sweep efficiencies obtained. The model simulates an invasion process, in which gas invades a porous medium occupied by a surfactant solution. The controlling parameter is the snap-off probability, which in turn determines the foam quality for various size distributions of pores and throats. For the front to advance, the applied pressure gradient needs to be sufficiently high to displace a series of lamellae along a minimum capillary resistance (threshold) path. We determine this path using a novel algorithm. The fraction of the flowing lamellae, X{sub f} (and, consequently, the fraction of the trapped lamellae, X{sub f}) which are currently empirical, are also calculated. The model allows the delineation of conditions tinder which high-quality (strong) or low-quality (weak) foams form. In either case, the sweep efficiencies in displacements in various media are calculated. In particular, the invasion by foam of low permeability layers during injection in a heterogeneous system is demonstrated.

  12. Two 3D network complexes of Y(III) and Ce(III) with 2-fold interpenetration and reversible desorption-adsorption behavior of lattice water

    SciTech Connect

    Chu Wenjuan; He Yong; Zhao Qinghuan; Fan Yaoting; Hou Hongwei

    2010-10-15

    Two novel inorganic-organic 3D network, namely{l_brace}[Ln(L){sub 1.5}(H{sub 2}O){sub 2}].5H{sub 2}O{r_brace}n [Ln=Y (1), Ce (2); Ln(L){sub 1.5}(H{sub 2}O){sub 2}].5H{sub 2}O [Ln=Y (1), Ce (2)], have been prepared through the assembly of the ligand 1,2-bis[3-(1,2,4-triazolyl)-4-amino-5-carboxylmethylthio]ethane (H{sub 2}L) and lanthanide (III) salts under hydrothermal condition and structurally characterized by single-crystal X-ray diffractions. In complexes 1 and 2, the L{sup 2-} anions adopt three different coordination fashions (bidentate chelate, bidentate bridging and bidentate chelate bridging) connecting Ln(III) ions via the oxygen atoms from carboxylate moieties. Both 1 and 2 exhibit 3D network structures with 2-fold interpenetration. Interestingly, the reversible desorption-adsorption behavior of lattice water is significantly observed in the two compounds. The result shows their potential application as late-model water absorbent in the field of adsorption material. - Graphical abstract: Two inorganic-organic 3D network, namely {l_brace}[Ln(L){sub 1.5}(H{sub 2}O){sub 2}].5H{sub 2}O{r_brace}n [Ln=Y (1), Ce (2)], have been prepared under hydrothermal condition and structurally characterized by single-crystal X-ray diffractions. Both 1 and 2 exhibit 3D network structures with 2-fold interpenetration. Interestingly, the reversible desorption-adsorption behavior of lattice water is significantly observed in the two compounds. The result shows their potential application as late-model water absorbent in the field of adsorption material.

  13. Construction of a 3D porous network of copper film via a template-free deposition method with superior mechanical and electrical properties for micro-energy devices

    NASA Astrophysics Data System (ADS)

    Peng, Yuncheng; Wang, Yao; Deng, Yuan

    2016-08-01

    With the ever increasing level of performance of energy conversion micro-devices, such as thin-film solar cells and thermoelectric micro-generators or coolers, their reliability and stability still remain a challenge. The high electrical and mechanical stability of an electrode is two of the critical factors that affect the long-term life of devices. Here we show that these factors can be achieved by constructing a 3D porous network of nanostructures in copper film using facile magnetron sputtering technology without any templates. The constructed 3D porous network of nanostructures in Cu film provides not only the advantages of light weight, prominently high conductivity, and large elastic deformation, but also the ability to absorb stress, preventing crack propagation, which is crucial for electrodes to maintain stable electrical and mechanical properties under working conditions. The nanopores inside the 3D network are capable of unrestrained deformation under applied stress resulting in strong elastic recovery. This work puts forward a feasible solution for manufacturing electrodes with excellent electrical and mechanical properties for micro-energy devices.

  14. Enhanced Retention of Chemotactic Bacteria in a Pore Network with Residual NAPL Contamination.

    PubMed

    Wang, Xiaopu; Lanning, Larry M; Ford, Roseanne M

    2016-01-01

    Nonaqueous-phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil. Chemotaxis enhances the mixing of bacteria with contaminant sources in low-permeability regions, which may not be readily accessible by advection and dispersion alone. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater aquifer. NAPL droplets (toluene) were trapped within a fine pore network, and bacteria were injected through a highly conductive adjacent macrochannel. Chemotactic bacteria (Pseudomonas putida F1) exhibited greater accumulation near the pore network at 0.5 m/day than both the nonchemotactic control and the chemotactic bacteria at a higher groundwater velocity of 5 m/day. Chemotactic bacteria accumulated in the vicinity of NAPL droplets, and the accumulation was 15% greater than a nonchemotactic mutant. Indirect evidence showed that chemotactic bacteria were retained within the contaminated low-permeability region longer than nonchemotactic bacteria at 0.25 m/day. This retention was diminished at 5 m/day. Numerical solutions of the bacterial-transport equations were consistent with the experimental results. Because toluene is degraded by P. putida F1, the accumulation of chemotactic bacteria around NAPL sources is expected to increase contaminant consumption and improve the efficiency of bioremediation. PMID:26633578

  15. Fabrication of Highly Stretchable Conductors Based on 3D Printed Porous Poly(dimethylsiloxane) and Conductive Carbon Nanotubes/Graphene Network.

    PubMed

    Duan, Shasha; Yang, Ke; Wang, Zhihui; Chen, Mengting; Zhang, Ling; Zhang, Hongbo; Li, Chunzhong

    2016-01-27

    The combination of carbon nanomaterial with three-dimensional (3D) porous polymer substrates has been demonstrated to be an effective approach to manufacture high-performance stretchable conductive materials (SCMs). However, it remains a challenge to fabricate 3D-structured SCMs with outstanding electrical conductivity capability under large strain in a facile way. In this work, the 3D printing technique was employed to prepare 3D porous poly(dimethylsiloxane) (O-PDMS) which was then integrated with carbon nanotubes and graphene conductive network and resulted in highly stretchable conductors (OPCG). Two types of OPCG were prepared, and it has been demonstrated that the OPCG with split-level structure exhibited both higher electrical conductivity and superior retention capability under deformations, which was illustrated by using a finite element method. The specially designed split-level OPCG is capable of sustaining both large strain and repeated deformations showing huge potential in the application of next-generation stretchable electronics. PMID:26713456

  16. Experimental Diagenesis and 3D Printing of Evolving Carbonate Microstructures

    NASA Astrophysics Data System (ADS)

    Vanorio, T.

    2014-12-01

    Understanding how rock microstructures and, in turn, the spatial distribution of the properties of the rock skeleton (porosity, permeability, and elastic properties) evolve because of time-variant, thermo-chemo-mechanical processes is fundamental to decipher changes in the earth's crust due to rock-fluid interactions using remote geophysical monitoring methods. Laboratory experiments undoubtedly play a vital role in understanding the underlying basic rules that are needed to inform both simulations and modeling. Nevertheless, capturing coupled chemo-mechanical processes experimentally is a very challenging problem because as pore space deforms chemo-mechanically, the fluid reacts and flows through a deforming pore space. The result is that as much as we strive to achieve controlled conditions in laboratory experiments, it is extremely difficult to control for all of the possible responses of the highly heterogeneous pore network. To overcome such a limitation, we often resort to the fabrication of rock samples in the laboratory. Nevertheless, analogs are not rocks. This level of complexity requires an approach that advances beyond the limitations of each method, be it experimental or computational. I present an approach that takes advantage of the favorable aspects of experimental diagenesis, multi-scale imaging techniques (from pore scale to 3D rock volumes) and 3D printed models of varying carbonate microstructures. This approach allows us to study the evolution of natural pore network geometries from diagenesis experiments, use the basic rules of the evolving microstructures to drive the digital change of the pore network of the printed models in a well-controlled fashion as much possible in the analog experiments, and then iteratively measure the properties of the printed models at the scale of the laboratory. This integration can help make sense of the trackless evolution of properties in apparently scattered datasets such as those characterizing carbonate

  17. 3D Printing and Digital Rock Physics for Geomaterials

    NASA Astrophysics Data System (ADS)

    Martinez, M. J.; Yoon, H.; Dewers, T. A.

    2015-12-01

    Imaging techniques for the analysis of porous structures have revolutionized our ability to quantitatively characterize geomaterials. Digital representations of rock from CT images and physics modeling based on these pore structures provide the opportunity to further advance our quantitative understanding of fluid flow, geomechanics, and geochemistry, and the emergence of coupled behaviors. Additive manufacturing, commonly known as 3D printing, has revolutionized production of custom parts with complex internal geometries. For the geosciences, recent advances in 3D printing technology may be co-opted to print reproducible porous structures derived from CT-imaging of actual rocks for experimental testing. The use of 3D printed microstructure allows us to surmount typical problems associated with sample-to-sample heterogeneity that plague rock physics testing and to test material response independent from pore-structure variability. Together, imaging, digital rocks and 3D printing potentially enables a new workflow for understanding coupled geophysical processes in a real, but well-defined setting circumventing typical issues associated with reproducibility, enabling full characterization and thus connection of physical phenomena to structure. In this talk we will discuss the possibilities that these technologies can bring to geosciences and present early experiences with coupled multiscale experimental and numerical analysis using 3D printed fractured rock specimens. In particular, we discuss the processes of selection and printing of transparent fractured specimens based on 3D reconstruction of micro-fractured rock to study fluid flow characterization and manipulation. Micro-particle image velocimetry is used to directly visualize 3D single and multiphase flow velocity in 3D fracture networks. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U

  18. Chemical sensing and imaging in microfluidic pore network structures relevant to natural carbon cycling and industrial carbon sequestration

    SciTech Connect

    Grate, Jay W.; Zhang, Changyong; Wilkins, Michael J.; Warner, Marvin G.; Anheier, Norman C.; Suter, Jonathan D.; Kelly, Ryan T.; Oostrom, Martinus

    2013-06-11

    Energy and climate change represent significant factors in global security. Atmospheric carbon dioxide levels, while global in scope, are influenced by pore-scale phenomena in the subsurface. We are developing tools to visualize and investigate processes in pore network microfluidic structures with transparent covers as representations of normally-opaque porous media. In situ fluorescent oxygen sensing methods and fluorescent cellulosic materials are being used to investigate processes related to terrestrial carbon cycling involving cellulytic respiring microorganisms. These structures also enable visualization of water displacement from pore spaces by hydrophobic fluids, including carbon dioxide, in studies related to carbon sequestration.

  19. Permeability evolution due to dissolution and precipitation of carbonates using reactive transport modeling in pore networks

    NASA Astrophysics Data System (ADS)

    Nogues, Juan P.; Fitts, Jeffrey P.; Celia, Michael A.; Peters, Catherine A.

    2013-09-01

    A reactive transport model was developed to simulate reaction of carbonates within a pore network for the high-pressure CO2-acidified conditions relevant to geological carbon sequestration. The pore network was based on a synthetic oolithic dolostone. Simulation results produced insights that can inform continuum-scale models regarding reaction-induced changes in permeability and porosity. As expected, permeability increased extensively with dissolution caused by high concentrations of carbonic acid, but neither pH nor calcite saturation state alone was a good predictor of the effects, as may sometimes be the case. Complex temporal evolutions of interstitial brine chemistry and network structure led to the counterintuitive finding that a far-from-equilibrium solution produced less permeability change than a nearer-to-equilibrium solution at the same pH. This was explained by the pH buffering that increased carbonate ion concentration and inhibited further reaction. Simulations of different flow conditions produced a nonunique set of permeability-porosity relationships. Diffusive-dominated systems caused dissolution to be localized near the inlet, leading to substantial porosity change but relatively small permeability change. For the same extent of porosity change caused from advective transport, the domain changed uniformly, leading to a large permeability change. Regarding precipitation, permeability changes happen much slower compared to dissolution-induced changes and small amounts of precipitation, even if located only near the inlet, can lead to large changes in permeability. Exponent values for a power law that relates changes in permeability and porosity ranged from 2 to 10, but a value of 6 held constant when conditions led to uniform changes throughout the domain.

  20. Arrays of 3D double-network hydrogels for the high-throughput discovery of materials with enhanced physical and biological properties.

    PubMed

    Duffy, Cairnan; Venturato, Andrea; Callanan, Anthony; Lilienkampf, Annamaria; Bradley, Mark

    2016-04-01

    Synthetic hydrogels are attractive biomaterials due to their similarity to natural tissues and their chemical tunability, which can impart abilities to respond to environmental cues, e.g. temperature, pH and light. The mechanical properties of hydrogels can be enhanced by the generation of a double-network. Here, we report the development of an array platform that allows the macroscopic synthesis of up to 80 single- and double-network hydrogels on a single microscope slide. This new platform allows for the screening of hydrogels as 3D features in a high-throughput format with the added dimension of significant control over the compressive and tensile properties of the materials, thus widening their potential application. The platform is adaptable to allow different hydrogels to be generated, with the potential ability to tune and alter the first and second network, and represents an exciting tool in material and biomaterial discovery. PMID:26712601

  1. Liquid CO2 displacement of water in a dual-permeability pore network micromodel.

    PubMed

    Zhang, Changyong; Oostrom, Mart; Grate, Jay W; Wietsma, Thomas W; Warner, Marvin G

    2011-09-01

    Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO(2) (LCO(2))-water displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over 2 orders of magnitude. LCO(2) displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO(2) displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO(2) saturation (S(LCO2)) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO(2) resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict S(LCO2) in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated S(LCO2). PMID:21774502

  2. The Locust Standard Brain: A 3D Standard of the Central Complex as a Platform for Neural Network Analysis

    PubMed Central

    el Jundi, Basil; Heinze, Stanley; Lenschow, Constanze; Kurylas, Angela; Rohlfing, Torsten; Homberg, Uwe

    2009-01-01

    Many insects use the pattern of polarized light in the sky for spatial orientation and navigation. We have investigated the polarization vision system in the desert locust. To create a common platform for anatomical studies on polarization vision pathways, Kurylas et al. (2008) have generated a three-dimensional (3D) standard brain from confocal microscopy image stacks of 10 male brains, using two different standardization methods, the Iterative Shape Averaging (ISA) procedure and the Virtual Insect Brain (VIB) protocol. Comparison of both standardization methods showed that the VIB standard is ideal for comparative volume analysis of neuropils, whereas the ISA standard is the method of choice to analyze the morphology and connectivity of neurons. The central complex is a key processing stage for polarization information in the locust brain. To investigate neuronal connections between diverse central-complex neurons, we generated a higher-resolution standard atlas of the central complex and surrounding areas, using the ISA method based on brain sections from 20 individual central complexes. To explore the usefulness of this atlas, two central-complex neurons, a polarization-sensitive columnar neuron (type CPU1a) and a tangential neuron that is activated during flight, the giant fan-shaped (GFS) neuron, were reconstructed 3D from brain sections. To examine whether the GFS neuron is a candidate to contribute to synaptic input to the CPU1a neuron, we registered both neurons into the standardized central complex. Visualization of both neurons revealed a potential connection of the CPU1a and GFS neurons in layer II of the upper division of the central body. PMID:20161763

  3. A lattice gas automata model for heterogeneous chemical reactions at mineral surfaces and in pore networks

    SciTech Connect

    Wells, J.T. . Dept. of Geological Sciences); Janecky, D.R.; Travis, B.J. )

    1990-01-15

    A lattice gas automata (LGA) model is described, which couples solute transport with chemical reactions at mineral surfaces and in pore networks. Chemical reactions and transport are integrated into a FHP-I LGA code as a module so that the approach is readily transportable to other codes. Diffusion in a box calculations are compared to finite element Fickian diffusion results and provide an approach to quantifying space-time ratios of the models. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the LGA approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible. 20 refs., 8 figs.

  4. Individual 3D region-of-interest atlas of the human brain: neural-network-based tissue classification with automatic training point extraction

    NASA Astrophysics Data System (ADS)

    Wagenknecht, Gudrun; Kaiser, Hans-Juergen; Obladen, Thorsten; Sabri, Osama; Buell, Udalrich

    2000-06-01

    The purpose of individual 3D region-of-interest atlas extraction is to automatically define anatomically meaningful regions in 3D MRI images for quantification of functional parameters (PET, SPECT: rMRGlu, rCBF). The first step of atlas extraction is to automatically classify brain tissue types into gray matter (GM), white matter (WM), cerebrospinal fluid (CSF), scalp/bone (SB) and background (BG). A feed-forward neural network with back-propagation training algorithm is used and compared to other numerical classifiers. It can be trained by a sample from the individual patient data set in question. Classification is done by a 'winner takes all' decision. Automatic extraction of a user-specified number of training points is done in a cross-sectional slice. Background separation is done by simple region growing. The most homogeneous voxels define the region for WM training point extraction (TPE). Non-white-matter and nonbackground regions are analyzed for GM and CSF training points. For SB TPE, the distance from the BG region is one feature. For each class, spatially uniformly distributed training points are extracted by a random generator from these regions. Simulated and real 3D MRI images are analyzed and error rates for TPE and classification calculated. The resulting class images can be analyzed for extraction of anatomical ROIs.

  5. Design of AN Intelligent Individual Evacuation Model for High Rise Building Fires Based on Neural Network Within the Scope of 3d GIS

    NASA Astrophysics Data System (ADS)

    Atila, U.; Karas, I. R.; Turan, M. K.; Rahman, A. A.

    2013-09-01

    One of the most dangerous disaster threatening the high rise and complex buildings of today's world including thousands of occupants inside is fire with no doubt. When we consider high population and the complexity of such buildings it is clear to see that performing a rapid and safe evacuation seems hard and human being does not have good memories in case of such disasters like world trade center 9/11. Therefore, it is very important to design knowledge based realtime interactive evacuation methods instead of classical strategies which lack of flexibility. This paper presents a 3D-GIS implementation which simulates the behaviour of an intelligent indoor pedestrian navigation model proposed for a self -evacuation of a person in case of fire. The model is based on Multilayer Perceptron (MLP) which is one of the most preferred artificial neural network architecture in classification and prediction problems. A sample fire scenario following through predefined instructions has been performed on 3D model of the Corporation Complex in Putrajaya (Malaysia) and the intelligent evacuation process has been realized within a proposed 3D-GIS based simulation.

  6. 3-D ADI-FDTD modeling of GPR backscatter from complex targets for the training of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Sassen, D. S.; Everett, M. E.

    2007-12-01

    Artificial neural networks can provide approximate solutions to ground-penetrating radar (GPR) problems in cases where real time performance is needed. Examples include discrimination of landmines or UXO's, and in circumstances that require a high number of successive forward problems, for example inversion or imaging. The training of neural networks to work within even a limited range of targets and electromagnetic properties requires a large set of successive examples generated from numerical methods such as finite difference time domain (FDTD). The traditional FDTD technique suffers from numerical dispersion unless time steps are kept below the Courant stability limit. The accurate modeling of electromagnetic scattering by complex targets require a refined grid, subgrids, or conformal grids that can significantly increase computation time, making neural network training inefficient. A relatively recent FDTD technique, ADI-FDTD, uses implicit equations that help to cancel numerical dispersion and allow for unconditionally stable modeling of EM propagation and therefore is not bound by the Courant stability limit. The technique is especially efficient for the accurate modeling of complex targets. Our ADI-FDTD code includes the ability to refine the model grid and to implement a conformal gridding to improve model accuracy without effecting the overall computation time. We will explore the tradeoff in computation time and accuracy in modeling the GPR backscatter of various targets using both the ADI-FDTD technique and the traditional FDTD technique for the purpose of neural network training.

  7. Principal curves for lumen center extraction and flow channel width estimation in 3-D arterial networks: theory, algorithm, and validation.

    PubMed

    Wong, Wilbur C K; So, Ronald W K; Chung, Albert C S

    2012-04-01

    We present an energy-minimization-based framework for locating the centerline and estimating the width of tubelike objects from their structural network with a nonparametric model. The nonparametric representation promotes simple modeling of nested branches and n -way furcations, i.e., structures that abound in an arterial network, e.g., a cerebrovascular circulation. Our method is capable of extracting the entire vascular tree from an angiogram in a single execution with a proper initialization. A succinct initial model from the user with arterial network inlets, outlets, and branching points is sufficient for complex vasculature. The novel method is based upon the theory of principal curves. In this paper, theoretical extension to grayscale angiography is discussed, and an algorithm to find an arterial network as principal curves is also described. Quantitative validation on a number of simulated data sets, synthetic volumes of 19 BrainWeb vascular models, and 32 Rotterdam Coronary Artery volumes was conducted. We compared the algorithm to a state-of-the-art method and further tested it on two clinical data sets. Our algorithmic outputs-lumen centers and flow channel widths-are important to various medical and clinical applications, e.g., vasculature segmentation, registration and visualization, virtual angioscopy, and vascular atlas formation and population study. PMID:22167625

  8. Sparse short-distance connections enhance calcium wave propagation in a 3D model of astrocyte networks

    PubMed Central

    Lallouette, Jules; De Pittà, Maurizio; Ben-Jacob, Eshel; Berry, Hugues

    2014-01-01

    Traditionally, astrocytes have been considered to couple via gap-junctions into a syncytium with only rudimentary spatial organization. However, this view is challenged by growing experimental evidence that astrocytes organize as a proper gap-junction mediated network with more complex region-dependent properties. On the other hand, the propagation range of intercellular calcium waves (ICW) within astrocyte populations is as well highly variable, depending on the brain region considered. This suggests that the variability of the topology of gap-junction couplings could play a role in the variability of the ICW propagation range. Since this hypothesis is very difficult to investigate with current experimental approaches, we explore it here using a biophysically realistic model of three-dimensional astrocyte networks in which we varied the topology of the astrocyte network, while keeping intracellular properties and spatial cell distribution and density constant. Computer simulations of the model suggest that changing the topology of the network is indeed sufficient to reproduce the distinct ranges of ICW propagation reported experimentally. Unexpectedly, our simulations also predict that sparse connectivity and restriction of gap-junction couplings to short distances should favor propagation while long–distance or dense connectivity should impair it. Altogether, our results provide support to recent experimental findings that point toward a significant functional role of the organization of gap-junction couplings into proper astroglial networks. Dynamic control of this topology by neurons and signaling molecules could thus constitute a new type of regulation of neuron-glia and glia-glia interactions. PMID:24795613

  9. Capturing 3D resistivity of semi-arid karstic subsurface in varying moisture conditions using a wireless sensor network

    NASA Astrophysics Data System (ADS)

    Barnhart, K.; Oden, C. P.

    2012-12-01

    The dissolution of soluble bedrock results in surface and subterranean karst channels, which comprise 7-10% of the dry earth's surface. Karst serves as a preferential conduit to focus surface and subsurface water but it is difficult to exploit as a water resource or protect from pollution because of irregular structure and nonlinear hydrodynamic behavior. Geophysical characterization of karst commonly employs resistivity and seismic methods, but difficulties arise due to low resistivity contrast in arid environments and insufficient resolution of complex heterogeneous structures. To help reduce these difficulties, we employ a state-of-the-art wireless geophysical sensor array, which combines low-power radio telemetry and solar energy harvesting to enable long-term in-situ monitoring. The wireless aspect removes topological constraints common with standard wired resistivity equipment, which facilitates better coverage and/or sensor density to help improve aspect ratio and resolution. Continuous in-situ deployment allows data to be recorded according to nature's time scale; measurements are made during infrequent precipitation events which can increase resistivity contrast. The array is coordinated by a smart wireless bridge that continuously monitors local soil moisture content to detect when precipitation occurs, schedules resistivity surveys, and periodically relays data to the cloud via 3G cellular service. Traditional 2/3D gravity and seismic reflection surveys have also been conducted to clarify and corroborate results.

  10. Pore Pressure prediction in shale gas reservoirs using neural network and fuzzy logic with an application to Barnett Shale.

    NASA Astrophysics Data System (ADS)

    Aliouane, Leila; Ouadfeul, Sid-Ali; Boudella, Amar

    2015-04-01

    The main goal of the proposed idea is to use the artificial intelligence such as the neural network and fuzzy logic to predict the pore pressure in shale gas reservoirs. Pore pressure is a very important parameter that will be used or estimation of effective stress. This last is used to resolve well-bore stability problems, failure plan identification from Mohr-Coulomb circle and sweet spots identification. Many models have been proposed to estimate the pore pressure from well-logs data; we can cite for example the equivalent depth model, the horizontal model for undercompaction called the Eaton's model…etc. All these models require a continuous measurement of the slowness of the primary wave, some thing that is not easy during well-logs data acquisition in shale gas formtions. Here, we suggest the use the fuzzy logic and the multilayer perceptron neural network to predict the pore pressure in two horizontal wells drilled in the lower Barnett shale formation. The first horizontal well is used for the training of the fuzzy set and the multilayer perecptron, the input is the natural gamma ray, the neutron porosity, the slowness of the compression and shear wave, however the desired output is the estimated pore pressure using Eaton's model. Data of another horizontal well are used for generalization. Obtained results clearly show the power of the fuzzy logic system than the multilayer perceptron neural network machine to predict the pore pressure in shale gas reservoirs. Keywords: artificial intelligence, fuzzy logic, pore pressure, multilayer perecptron, Barnett shale.

  11. Self-Assembled 3D Graphene Monolith from Solution.

    PubMed

    Lv, Wei; Zhang, Chen; Li, Zhengjie; Yang, Quan-Hong

    2015-02-19

    Three-dimensional (3D) graphene-assembled monoliths (GAs), especially ones prepared by self-assembly in the liquid phase, represent promising forms to realize the practical applications of graphene due to their high surface utilization and operability. However, the understanding of the assembly process and structure control of 3D GAs, as a new class of carbon materials, is quite inadequate. In this Perspective, we give a demonstration of the assembly process and discuss the key factors involved in the structure control of 3D GAs to pave the way for their future applications. It is shown that the assembly process starts with the phase separation, which is responsible for the formation of the 3D networked structure and liquid phase as the spacers avoid the parallel overlap of graphene layers and help form an interlinked pore system. Well-tailored graphene sheets and selected assembly media must be a precondition for a well-controlled assembly process and microstructure of a 3D GA. The potential applications in energy storage featuring high rate and high volumetric energy density demonstrate advantages of 3D GAs in real applications. PMID:26262482

  12. 3-D inversion of borehole-to-surface electrical data using a back-propagation neural network

    NASA Astrophysics Data System (ADS)

    Ho, Trong Long

    2009-08-01

    The "fluid-flow tomography", an advanced technique for geoelectrical survey based on the conventional mise-à-la-masse measurement, has been developed by Exploration Geophysics Laboratory at the Kyushu University. This technique is proposed to monitor fluid-flow behavior during water injection and production in a geothermal field. However data processing of this technique is very costly. In this light, this paper will discuss the solution to cost reduction by applying a neural network in the data processing. A case study in the Takigami geothermal field in Japan will be used to illustrate this. The achieved neural network in this case study is three-layered and feed-forward. The most successful learning algorithm in this network is the Resilient Propagation (RPROP). Consequently, the study advances the pragmatism of the "fluid-flow tomography" technique which can be widely used for geothermal fields. Accuracy of the solution is then verified by using root mean square (RMS) misfit error as an indicator.

  13. A one-dimensional analysis of sol-gel film-coating drying: Pore evolution, network shrinkage and stress development

    SciTech Connect

    Chen, K.S.; Schunk, P.R.

    1998-02-01

    Highly porous sol-gel films have potential applications as electrical and thermal insulators, catalyst supports, sensors, and membranes for gas separations. Pore dimensions in these sol-gel films are usually small e.g., on the order of tens of nanometers or less. Their successful fabrications, however, greatly depend on the fundamental understanding of mechanisms that underlie the phenomena of pore evolution, network shrinkage, and stress development since the final microstructure of a solid gel film is strongly affected by composition of its starting sol and its processing conditions. This report documents a simplified one-dimensional analysis of drying a solidifying sol-gel thin film coating supported by an impermeable solid substrate. Portions of this work were presented at the 1994 Annual Joint Meeting of the New Mexico Section of the American Ceramic Society and Materials Research Society in Albuquerque. The authors considered the solid/liquid two phase coexistent regime during the drying solidifying process in which solvent is removed continuously via evaporation, the solid phase grows significantly in mechanical strength, and pore space shrinks appreciably. From overall and differential mass balances and a force balance at equilibrium, coupled with empirical correlations of solid phase modulus and permeability to strain or deformation, the authors followed the evolution of pore space, solid phase elastic stress, and liquid phase hydrodynamic pressure; they also determined their respective values at equilibrium. By assuming microscopic pore shape models, they estimated and compared the predicted mean pore radii. Their simplified one-dimensional analysis shows that the final mean pore radius is controlled by four parameters: pore-liquid surface tension, solid phase modulus, mean pore radius, and porosity at the initial stress-free state. The one-dimensional model can be employed to guide process design and optimization in sol-gel film fabrications.

  14. Efficient training of convolutional deep belief networks in the frequency domain for application to high-resolution 2D and 3D images.

    PubMed

    Brosch, Tom; Tam, Roger

    2015-01-01

    Deep learning has traditionally been computationally expensive, and advances in training methods have been the prerequisite for improving its efficiency in order to expand its application to a variety of image classification problems. In this letter, we address the problem of efficient training of convolutional deep belief networks by learning the weights in the frequency domain, which eliminates the time-consuming calculation of convolutions. An essential consideration in the design of the algorithm is to minimize the number of transformations to and from frequency space. We have evaluated the running time improvements using two standard benchmark data sets, showing a speed-up of up to 8 times on 2D images and up to 200 times on 3D volumes. Our training algorithm makes training of convolutional deep belief networks on 3D medical images with a resolution of up to 128×128×128 voxels practical, which opens new directions for using deep learning for medical image analysis. PMID:25380341

  15. Enhanced Retention of Chemotactic Bacteria in a Pore Network with Residual NAPL Contamination

    NASA Astrophysics Data System (ADS)

    Ford, R.; Wang, X.

    2013-12-01

    Nonaqueous phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil matrix. Residual NAPL ganglia remain trapped in regions where the hydraulic conductivity is relatively low. Bioremediation processes depend on adequate mixing of microbial populations and the groundwater contaminants that they degrade. The ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, known as chemotaxis, can enhance the mixing of bacteria with contaminant sources that may not be readily accessible by advection and dispersion alone. The impact of chemotaxis on bacterial abundance within a low conductivity NAPL-contaminated region of a well-characterized porous matrix was investigated. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater system. NAPL ganglia (toluene) were trapped within a fine pore network, and bacteria were injected into the system through a highly conductive adjacent channel. Chemotactic bacteria (P. putida F1) migrated preferentially towards and accumulated in the vicinity of NAPL contaminant sources. The accumulation of chemotactic bacteria was 15% greater in comparison to a nonchemotactic mutant (P. putida F1 CheA). Bacteria in the microfluidic device were subjected to different flow velocities from 0.25 to 5 m/d encompassing the range of typical groundwater flow rates. Chemotactic bacteria exhibited greater accumulation near the intersection between the macrochannel and the porous network at a flow velocity of 0.5 m/d than both the nonchemotactic mutant control and the chemotactic bacteria at a higher flow velocity of 5 m/d. Breakthrough curves observed at the outlet provided indirect evidence that chemotactic bacteria were retained within the contaminated low permeable region for a longer time than the nonchemotactic bacteria at a flow velocity of 0.25 m/d. This retention was

  16. 3-D components of a biological neural network visualized in computer generated imagery. I - Macular receptive field organization

    NASA Technical Reports Server (NTRS)

    Ross, Muriel D.; Cutler, Lynn; Meyer, Glenn; Lam, Tony; Vaziri, Parshaw

    1990-01-01

    Computer-assisted, 3-dimensional reconstructions of macular receptive fields and of their linkages into a neural network have revealed new information about macular functional organization. Both type I and type II hair cells are included in the receptive fields. The fields are rounded, oblong, or elongated, but gradations between categories are common. Cell polarizations are divergent. Morphologically, each calyx of oblong and elongated fields appears to be an information processing site. Intrinsic modulation of information processing is extensive and varies with the kind of field. Each reconstructed field differs in detail from every other, suggesting that an element of randomness is introduced developmentally and contributes to endorgan adaptability.

  17. A novel method for identifying a graph-based representation of 3-D microvascular networks from fluorescence microscopy image stacks.

    PubMed

    Almasi, Sepideh; Xu, Xiaoyin; Ben-Zvi, Ayal; Lacoste, Baptiste; Gu, Chenghua; Miller, Eric L

    2015-02-01

    A novel approach to determine the global topological structure of a microvasculature network from noisy and low-resolution fluorescence microscopy data that does not require the detailed segmentation of the vessel structure is proposed here. The method is most appropriate for problems where the tortuosity of the network is relatively low and proceeds by directly computing a piecewise linear approximation to the vasculature skeleton through the construction of a graph in three dimensions whose edges represent the skeletal approximation and vertices are located at Critical Points (CPs) on the microvasculature. The CPs are defined as vessel junctions or locations of relatively large curvature along the centerline of a vessel. Our method consists of two phases. First, we provide a CP detection technique that, for junctions in particular, does not require any a priori geometric information such as direction or degree. Second, connectivity between detected nodes is determined via the solution of a Binary Integer Program (BIP) whose variables determine whether a potential edge between nodes is or is not included in the final graph. The utility function in this problem reflects both intensity-based and structural information along the path connecting the two nodes. Qualitative and quantitative results confirm the usefulness and accuracy of this method. This approach provides a mean of correctly capturing the connectivity patterns in vessels that are missed by more traditional segmentation and binarization schemes because of imperfections in the images which manifest as dim or broken vessels. PMID:25515433

  18. Architectural improvements and 28 nm FPGA implementation of the APEnet+ 3D Torus network for hybrid HPC systems

    NASA Astrophysics Data System (ADS)

    Ammendola, Roberto; Biagioni, Andrea; Frezza, Ottorino; Lo Cicero, Francesca; Stanislao Paolucci, Pier; Lonardo, Alessandro; Rossetti, Davide; Simula, Francesco; Tosoratto, Laura; Vicini, Piero

    2014-06-01

    Modern Graphics Processing Units (GPUs) are now considered accelerators for general purpose computation. A tight interaction between the GPU and the interconnection network is the strategy to express the full potential on capability computing of a multi-GPU system on large HPC clusters; that is the reason why an efficient and scalable interconnect is a key technology to finally deliver GPUs for scientific HPC. In this paper we show the latest architectural and performance improvement of the APEnet+ network fabric, a FPGA-based PCIe board with 6 fully bidirectional off-board links with 34 Gbps of raw bandwidth per direction, and X8 Gen2 bandwidth towards the host PC. The board implements a Remote Direct Memory Access (RDMA) protocol that leverages upon peer-to-peer (P2P) capabilities of Fermi- and Kepler-class NVIDIA GPUs to obtain real zero-copy, low-latency GPU-to-GPU transfers. Finally, we report on the development activities for 2013 focusing on the adoption of the latest generation 28 nm FPGAs and the preliminary tests performed on this new platform.

  19. A coupled 3D-1D numerical monodomain solver for cardiac electrical activation in the myocardium with detailed Purkinje network

    NASA Astrophysics Data System (ADS)

    Vergara, Christian; Lange, Matthias; Palamara, Simone; Lassila, Toni; Frangi, Alejandro F.; Quarteroni, Alfio

    2016-03-01

    We present a model for the electrophysiology in the heart to handle the electrical propagation through the Purkinje system and in the myocardium, with two-way coupling at the Purkinje-muscle junctions. In both the subproblems the monodomain model is considered, whereas at the junctions a resistor element is included that induces an orthodromic propagation delay from the Purkinje network towards the heart muscle. We prove a sufficient condition for convergence of a fixed-point iterative algorithm to the numerical solution of the coupled problem. Numerical comparison of activation patterns is made with two different combinations of models for the coupled Purkinje network/myocardium system, the eikonal/eikonal and the monodomain/monodomain models. Test cases are investigated for both physiological and pathological activation of a model left ventricle. Finally, we prove the reliability of the monodomain/monodomain coupling on a realistic scenario. Our results underlie the importance of using physiologically realistic Purkinje-trees with propagation solved using the monodomain model for simulating cardiac activation.

  20. The 3D structure of the collagen fibril network in human trabecular bone: relation to trabecular organization.

    PubMed

    Reznikov, Natalie; Chase, Hila; Brumfeld, Vlad; Shahar, Ron; Weiner, Steve

    2015-02-01

    Trabecular bone is morphologically and functionally different from compact bone at the tissue level, but both are composed of lamellae at the micrometer-scale level. We present a three-dimensional study of the collagenous network of human trabecular lamellar bone from the proximal femur using the FIB-SEM serial surface view method. The results are compared to human compact lamellar bone of the femoral shaft, studied by the same method. Both demineralized trabecular and compact lamellar bone display the same overall structural organization, namely the presence of ordered and disordered materials and the confinement of the canalicular network to the disordered material. However, in trabecular bone lamellae a significant proportion of the ordered collagen fibril arrays is aligned with the long axis of the trabecula and, unlike in compact bone, is not related to the anatomical axis of the whole femur. The remaining ordered collagen fibrils are offset from the axis of a trabecula either by about 30° or 70°. Interestingly, at the tissue scale of millimeters, the most abundant angles between any two connected trabeculae - the inter-trabecular angles - center around 30° and 70°. This implies that within a framework of interconnected trabeculae the same lamellar structure will always have a significant component of the fibrils aligned with the long axes of connected trabeculae. This structural complementarity at different hierarchical levels presumably reflects an adaptation of trabecular bone to function. PMID:25445457

  1. A novel method for identifying a graph-based representation of 3-D microvascular networks from fluorescence microscopy image stacks

    PubMed Central

    Xu, Xiaoyin; Ben-Zvi, Ayal; Lacoste, Baptiste; Gu, Chenghua; Miller, Eric L.

    2016-01-01

    A novel approach to determine the global topological structure of a microvasculature network from noisy and low-resolution fluorescence microscopy data that does not require the detailed segmentation of the vessel structure is proposed here. The method is most appropriate for problems where the tortuosity of the network is relatively low and proceeds by directly computing a piecewise linear approximation to the vasculature skeleton through the construction of a graph in three dimensions whose edges represent the skeletal approximation and vertices are located at Critical Points (CPs) on the microvasculature. The CPs are defined as vessel junctions or locations of relatively large curvature along the centerline of a vessel. Our method consists of two phases. First, we provide a CP detection technique that, for junctions in particular, does not require any a priori geometric information such as direction or degree. Second, connectivity between detected nodes is determined via the solution of a Binary Integer Program (BIP) whose variables determine whether a potential edge between nodes is or is not included in the final graph. The utility function in this problem reflects both intensity-based and structural information along the path connecting the two nodes. Qualitative and quantitative results confirm the usefulness and accuracy of this method. This approach provides a mean of correctly capturing the connectivity patterns in vessels that are missed by more traditional segmentation and binarization schemes because of imperfections in the images which manifest as dim or broken vessels. PMID:25515433

  2. Integrated approach for quantification of fractured tight reservoir rocks: Porosity, permeability analyses and 3D fracture network characterisation on fractured dolomite samples

    NASA Astrophysics Data System (ADS)

    Voorn, Maarten; Barnhoorn, Auke; Exner, Ulrike; Baud, Patrick; Reuschlé, Thierry

    2015-04-01

    Fractured reservoir rocks make up an important part of the hydrocarbon reservoirs worldwide. A detailed analysis of fractures and fracture networks in reservoir rock samples is thus essential to determine the potential of these fractured reservoirs. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this study, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna Basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. 3D μCT data is used to extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. The 3D analyses are complemented with thin sections made to provide some 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) of the µCT results towards more realistic reservoir conditions. Our results show that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and other

  3. Using genetic algorithms to optimize an active sensor network on a stiffened aerospace panel with 3D scanning laser vibrometry data

    NASA Astrophysics Data System (ADS)

    Marks, R.; Clarke, A.; Featherston, C.; Kawashita, L.; Paget, C.; Pullin, R.

    2015-07-01

    With the increasing complexity of aircraft structures and materials there is an essential need to continually monitor the structure for damage. This also drives the requirement for optimizing the location of sensors for damage detection to ensure full damage detection coverage of the structure whilst minimizing the number of sensors required, hence reducing costs, weight and data processing. An experiment was carried out to investigate the optimal sensor locations of an active sensor network for detecting adhesive disbonds of a stiffened panel. A piezoelectric transducer was coupled to two different stiffened aluminium panels; one healthy and one with a 25.4mm long disbond. The transducer was positioned at five individual locations to assess the effectiveness of damage detection at different transmission locations. One excitation frequency of 100kHz was used for this study. The panels were scanned with a 3D scanning laser vibrometer which represented a network of ‘ideal’ receiving transducers. The responses measured on the disbonded panel were cross- correlated with those measured on the healthy panel at a large number of potential sensor locations. This generated a cost surface which a genetic algorithm could interrogate in order to find the optimal sensor locations for a given size of sensor network. Probabilistic techniques were used to consider multiple disbond location scenarios, in order to optimise the sensor network for maximum probability of detection across a range of disbond locations.

  4. 3D modelling of the active normal fault network in the Apulian Ridge (Eastern Mediterranean Sea): Integration of seismic and bathymetric data with implicit surface methods

    NASA Astrophysics Data System (ADS)

    Bistacchi, Andrea; Pellegrini, Caludio; Savini, Alessandra; Marchese, Fabio

    2016-04-01

    The Apulian ridge (North-eastern Ionian Sea, Mediterranean), interposed between the facing Apennines and Hellenides subduction zones (to the west and east respectively), is characterized by thick cretaceous carbonatic sequences and discontinuous tertiary deposits crosscut by a penetrative network of NNW-SSE normal faults. These are exposed onshore in Puglia, and are well represented offshore in a dataset composed of 2D seismics and wells collected by oil companies from the '60s to the '80s, more recent seismics collected during research projects in the '90s, recent very high resolution seismics (VHRS - Sparker and Chirp-sonar data), multibeam echosounder bathymetry, and sedimentological and geo-chronological analyses of sediment samples collected on the seabed. Faults are evident in 2D seismics at all scales, and their along-strike geometry and continuity can be characterized with multibeam bathymetric data, which show continuous fault scarps on the seabed (only partly reworked by currents and covered by landslides). Fault scarps also reveal the finite displacement accumulated in the Holocene-Pleistocene. We reconstructed a 3D model of the fault network and suitable geological boundaries (mainly unconformities due to the discontinuous distribution of quaternary and tertiary sediments) with implicit surface methods implemented in SKUA/GOCAD. This approach can be considered very effective and allowed reconstructing in details complex structures, like the frequent relay zones that are particularly well imaged by seafloor geomorphology. Mutual cross-cutting relationships have been recognized between fault scarps and submarine mass-wasting deposits (Holocene-Pleistocene), indicating that, at least in places, these features are coeval, hence the fault network should be considered active. At the regional scale, the 3D model allowed measuring the horizontal WSW-ENE stretching, which can be associated to the bending moment applied to the Apulian Plate by the combined effect

  5. Euro3D Science Conference

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.

    2004-02-01

    The Euro3D RTN is an EU funded Research Training Network to foster the exploitation of 3D spectroscopy in Europe. 3D spectroscopy is a general term for spectroscopy of an area of the sky and derives its name from its two spatial + one spectral dimensions. There are an increasing number of instruments which use integral field devices to achieve spectroscopy of an area of the sky, either using lens arrays, optical fibres or image slicers, to pack spectra of multiple pixels on the sky (``spaxels'') onto a 2D detector. On account of the large volume of data and the special methods required to reduce and analyse 3D data, there are only a few centres of expertise and these are mostly involved with instrument developments. There is a perceived lack of expertise in 3D spectroscopy spread though the astronomical community and its use in the armoury of the observational astronomer is viewed as being highly specialised. For precisely this reason the Euro3D RTN was proposed to train young researchers in this area and develop user tools to widen the experience with this particular type of data in Europe. The Euro3D RTN is coordinated by Martin M. Roth (Astrophysikalisches Institut Potsdam) and has been running since July 2002. The first Euro3D science conference was held in Cambridge, UK from 22 to 23 May 2003. The main emphasis of the conference was, in keeping with the RTN, to expose the work of the young post-docs who are funded by the RTN. In addition the team members from the eleven European institutes involved in Euro3D also presented instrumental and observational developments. The conference was organized by Andy Bunker and held at the Institute of Astronomy. There were over thirty participants and 26 talks covered the whole range of application of 3D techniques. The science ranged from Galactic planetary nebulae and globular clusters to kinematics of nearby galaxies out to objects at high redshift. Several talks were devoted to reporting recent observations with newly

  6. Supercritical CO2 Dissolution and Mass Transfer in a Heterogeneous Pore Network under Drainage and Imbibition Conditions

    NASA Astrophysics Data System (ADS)

    Kneafsey, T. J.; Chang, C.; Zhou, Q.; Oostrom, M.; Wietsma, T. W.; Yu, Q.

    2015-12-01

    Dissolution trapping of supercritical CO2 (scCO2) is usually modeled by assuming instantaneous scCO2 dissolution and equilibrium phase partitioning. Our recent core-scale imbibition experiments show a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In our 2D sandstone-analogue micromodel experimental study, pore-scale scCO2 dissolution was inferred from imaging (1) drainage using a pH-sensitive water dye and (2) imbibition using a scCO2 dye. The drainage experiment was conducted by injecting scCO2 into the dissolved-CO2 (dsCO2)-free water-filled pore network. The time-lapse images of non-uniform dye intensities indicating varying pH show that dsCO2 concentration varies from zero to solubility in individual pores and pore clusters and the average concentration gradually increases with time. The different rates of dissolution in different pores/clusters can be attributed to (1) fast scCO2 dissolution at scCO2-water interfaces, (2) rate-limited mass transfer due to limited interface areas, and (3) a transition from rate-limited to diffusion-limited mass transfer, revealed by detailed analysis on selected pores and pore clusters. The imbibition experiments conducted by injecting deionized water at different rates show (1) water flow in channels bypassing scCO2 at high residual saturations, (2) subsequent, slow scCO2 depletion by dissolution and mass transfer as effluent dsCO2 concentration varies from 0.06% to 4.44% of solubility, and (3) creation of new water flow paths by dissolution, enhancing scCO2 depletion by coupled displacement and dissolution. Both the drainage and imbibitions experiments indicate non-equilibrium scCO2 dissolution in the centimeter-scale pore network over 4.5 hours and up to 14 hours, respectively. The pore-scale imaging can help better understand the effects of pore-throat characteristics on scCO2 dissolution and mass transfer during drainage and imbibition and the interplay between displacement and

  7. Europeana and 3D

    NASA Astrophysics Data System (ADS)

    Pletinckx, D.

    2011-09-01

    The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.

  8. Dual FIB-SEM 3D imaging and lattice boltzmann modeling of porosimetry and multiphase flow in chalk.

    SciTech Connect

    Rinehart, Alex; Petrusak, Robin; Heath, Jason E.; Dewers, Thomas A.; Yoon, Hongkyu

    2010-12-01

    Mercury intrusion porosimetry (MIP) is an often-applied technique for determining pore throat distributions and seal analysis of fine-grained rocks. Due to closure effects, potential pore collapse, and complex pore network topologies, MIP data interpretation can be ambiguous, and often biased toward smaller pores in the distribution. We apply 3D imaging techniques and lattice-Boltzmann modeling in interpreting MIP data for samples of the Cretaceous Selma Group Chalk. In the Mississippi Interior Salt Basin, the Selma Chalk is the apparent seal for oil and gas fields in the underlying Eutaw Fm., and, where unfractured, the Selma Chalk is one of the regional-scale seals identified by the Southeast Regional Carbon Sequestration Partnership for CO2 injection sites. Dual focused ion - scanning electron beam and laser scanning confocal microscopy methods are used for 3D imaging of nanometer-to-micron scale microcrack and pore distributions in the Selma Chalk. A combination of image analysis software is used to obtain geometric pore body and throat distributions and other topological properties, which are compared to MIP results. 3D data sets of pore-microfracture networks are used in Lattice Boltzmann simulations of drainage (wetting fluid displaced by non-wetting fluid via the Shan-Chen algorithm), which in turn are used to model MIP procedures. Results are used in interpreting MIP results, understanding microfracture-matrix interaction during multiphase flow, and seal analysis for underground CO2 storage.

  9. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    DOE PAGESBeta

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; Gable, Carl W.; Karra, Satish

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates massmore » balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.« less

  10. Particle tracking approach for transport in three-dimensional discrete fracture networks: Particle tracking in 3-D DFNs

    SciTech Connect

    Makedonska, Nataliia; Painter, Scott L.; Bui, Quan M.; Gable, Carl W.; Karra, Satish

    2015-09-16

    The discrete fracture network (DFN) model is a method to mimic discrete pathways for fluid flow through a fractured low-permeable rock mass, and may be combined with particle tracking simulations to address solute transport. However, experience has shown that it is challenging to obtain accurate transport results in three-dimensional DFNs because of the high computational burden and difficulty in constructing a high-quality unstructured computational mesh on simulated fractures. We present a new particle tracking capability, which is adapted to control volume (Voronoi polygons) flow solutions on unstructured grids (Delaunay triangulations) on three-dimensional DFNs. The locally mass-conserving finite-volume approach eliminates mass balance-related problems during particle tracking. The scalar fluxes calculated for each control volume face by the flow solver are used to reconstruct a Darcy velocity at each control volume centroid. The groundwater velocities can then be continuously interpolated to any point in the domain of interest. The control volumes at fracture intersections are split into four pieces, and the velocity is reconstructed independently on each piece, which results in multiple groundwater velocities at the intersection, one for each fracture on each side of the intersection line. This technique enables detailed particle transport representation through a complex DFN structure. Verified for small DFNs, the new simulation capability enables numerical experiments on advective transport in large DFNs to be performed. As a result, we demonstrate this particle transport approach on a DFN model using parameters similar to those of crystalline rock at a proposed geologic repository for spent nuclear fuel in Forsmark, Sweden.

  11. Global motions of the nuclear pore complex: insights from elastic network models.

    PubMed

    Lezon, Timothy R; Sali, Andrej; Bahar, Ivet

    2009-09-01

    The nuclear pore complex (NPC) is the gate to the nucleus. Recent determination of the configuration of proteins in the yeast NPC at approximately 5 nm resolution permits us to study the NPC global dynamics using coarse-grained structural models. We investigate these large-scale motions by using an extended elastic network model (ENM) formalism applied to several coarse-grained representations of the NPC. Two types of collective motions (global modes) are predicted by the ENMs to be intrinsically favored by the NPC architecture: global bending and extension/contraction from circular to elliptical shapes. These motions are shown to be robust against tested variations in the representation of the NPC, and are largely captured by a simple model of a toroid with axially varying mass density. We demonstrate that spoke multiplicity significantly affects the accessible number of symmetric low-energy modes of motion; the NPC-like toroidal structures composed of 8 spokes have access to highly cooperative symmetric motions that are inaccessible to toroids composed of 7 or 9 spokes. The analysis reveals modes of motion that may facilitate macromolecular transport through the NPC, consistent with previous experimental observations. PMID:19730674

  12. Characterizing two-phase flow relative permeabilities in chemicalflooding using a pore-scale network model

    SciTech Connect

    Liu, Qingjie; Shen, Pingping; Wu, Yu-Shu

    2004-03-15

    A dynamic pore-scale network model is presented for investigating the effects of interfacial tension and oil-water viscosity on relative permeability during chemical flooding. This model takes into account both viscous and capillary forces in analyzing the impact of chemical properties on flow behavior or displacement configuration, as opposed to the conventional or invasion percolation algorithm which incorporates capillary pressure only. The study results indicate that both water and oil relative-permeability curves are dependent strongly on interfacial tension as well as an oil-water viscosity ratio. In particular, water and oil relative-permeability curves are both found to shift upward as interfacial tension is reduced, and they both tend to become linear versus saturation once interfacial tension is at low values. In addition, the oil-water viscosity ratio appears to have only a small effect under conditions of high interfacial tension. When the interfacial tension is low, however, water relative permeability decreases more rapidly (with the increase in the aqueous-phase viscosity) than oil relative permeability. The breakthrough saturation of the aqueous phase during chemical flooding tends to decrease with the reduction of interfacial tension and may also be affected by the oil-water viscosity ratio.

  13. Late rectal bleeding after 3D-CRT for prostate cancer: development of a neural-network-based predictive model

    NASA Astrophysics Data System (ADS)

    Tomatis, S.; Rancati, T.; Fiorino, C.; Vavassori, V.; Fellin, G.; Cagna, E.; Mauro, F. A.; Girelli, G.; Monti, A.; Baccolini, M.; Naldi, G.; Bianchi, C.; Menegotti, L.; Pasquino, M.; Stasi, M.; Valdagni, R.

    2012-03-01

    The aim of this study was to develop a model exploiting artificial neural networks (ANNs) to correlate dosimetric and clinical variables with late rectal bleeding in prostate cancer patients undergoing radical radiotherapy and to compare the ANN results with those of a standard logistic regression (LR) analysis. 718 men included in the AIROPROS 0102 trial were analyzed. This multicenter protocol was characterized by the prospective evaluation of rectal toxicity, with a minimum follow-up of 36 months. Radiotherapy doses were between 70 and 80 Gy. Information was recorded for comorbidity, previous abdominal surgery, use of drugs and hormonal therapy. For each patient, a rectal dose-volume histogram (DVH) of the whole treatment was recorded and the equivalent uniform dose (EUD) evaluated as an effective descriptor of the whole DVH. Late rectal bleeding of grade ≥ 2 was considered to define positive events in this study (52 of 718 patients). The overall population was split into training and verification sets, both of which were involved in model instruction, and a test set, used to evaluate the predictive power of the model with independent data. Fourfold cross-validation was also used to provide realistic results for the full dataset. The LR was performed on the same data. Five variables were selected to predict late rectal bleeding: EUD, abdominal surgery, presence of hemorrhoids, use of anticoagulants and androgen deprivation. Following a receiver operating characteristic analysis of the independent test set, the areas under the curves (AUCs) were 0.704 and 0.655 for ANN and LR, respectively. When evaluated with cross-validation, the AUC was 0.714 for ANN and 0.636 for LR, which differed at a significance level of p = 0.03. When a practical discrimination threshold was selected, ANN could classify data with sensitivity and specificity both equal to 68.0%, whereas these values were 61.5% for LR. These data provide reasonable evidence that results obtained with

  14. 2D and 3D soil moisture imaging using a sensor-based platform moving inside a subsurface network of pipes

    NASA Astrophysics Data System (ADS)

    Gravalos, I.; Moshou, D.; Loutridis, S.; Gialamas, Th.; Kateris, D.; Bompolas, E.; Tsiropoulos, Z.; Xyradakis, P.; Fountas, S.

    2013-08-01

    In this study a prototype sensor-based platform moving inside a subsurface network of pipes with the task of monitoring the soil moisture content is presented. It comprises of a mobile platform, a modified commercial soil moisture sensor (Diviner 2000), a network of subsurface polyvinylchloride (PVC) access pipes, driving hardware and image processing software. The software allows the composition of two-dimensional (2D) or three-dimensional (3D) images with high accuracy and at a large scale. The 3D soil moisture images are created by using 2D slices for better illustration of the soil moisture variability. Three case studies of varying soil moisture content using an experimental soil tank were examined. In the first case study, the irrigation water was applied uniformly on the entire tank surface. In second and third case studies, the irrigation water was applied uniformly only on the surface of the intermediate and last part of the soil tank respectively. The processed images give a detailed description of the soil moisture distribution of a layer at 15 cm depth under the soil surface in the tank. In all case studies that have been investigated, the distribution of soil moisture was characterized by a significant variability (difference between poorly and well-drained regions) of the soil tank. A very poorly-drained region was located in the middle of the soil tank, while well-drained soil areas were located southwest and northeast. The knowledge of the spatial and temporal distribution of soil moisture is a valuable tool for proper management of crop irrigation.

  15. Structural Variations in the Uranyl/4,4'-Biphenyldicarboxylate System. Rare Examples of 2D → 3D Polycatenated Uranyl-Organic Networks.

    PubMed

    Thuéry, Pierre; Harrowfield, Jack

    2015-08-17

    4,4'-Biphenyldicarboxylic acid (H2L) was reacted with uranyl ions under solvo-hydrothermal conditions with variations in the experimental procedure (organic cosolvent, presence of additional 3d-block metal cations, and N-donor species), thus giving six complexes of the fully deprotonated acid that were characterized by their crystal structure and, in most cases, their emission spectrum. The three complexes [UO2(L)(DMA)] (1), [UO2(L)(NMP)] (2), and [UO2(L)(NMP)] (3) include the cosolvent as a coligand, and they crystallize as two-dimensional (2D) assemblies, with different combinations of the chelating and bridging-bidentate carboxylate coordination modes, resulting in two different topologies. Complex 4, [Ni(bipy)3][(UO2)2(L)2(C2O4)]·H2O, includes oxalate coligands generated in situ and contains an anionic planar two-dimensional (2D) assembly with a {6(3)} honeycomb topology. The same hexagonal geometry is found in the homoleptic complexes [Ni(bipy)3][(UO2)2(L)3]·6H2O (5) and [Ni(phen)3][(UO2)2(L)3]·4H2O (6), but the large size of the hexagonal rings in these cases (∼27 Å in the longest dimension) allows 2D → three-dimensional (3D) inclined polycatenation to occur, with the two families of networks either orthogonal in tetragonal complex 5 or at an angle of 73.4° in orthorhombic complex 6. The parallel networks are arranged in closely spaced groups of two, with possible π···π stacking interactions, and as many as four rods from four parallel nets pass through each ring of the inclined family of nets, an unusually high degree of catenation. These are the second cases only of 2D → 3D inclined polycatenation in uranyl-organic species. Emission spectra measured in the solid state show the usual vibronic fine structure, with variations in intensity and positions of maxima that are not simply connected with the number of equatorial donors and the presence of additional metal cations. PMID:26241368

  16. Temperature-Dependent Pore Space of Sea Ice: X-ray Computed-Tomography and Dual Model Network Analysis

    NASA Astrophysics Data System (ADS)

    Pringle, D.; Miner, J.; Glantz, R.; Hilpert, M.; Eicken, H.

    2006-12-01

    Sea ice provides a mechanical and thermal barrier between the atmosphere and ocean at high latitudes and is an important component of the climate system. It is a composite material with temperature- and salinity- dependent volume fractions of ice, brine and air. Our present interest is the microstructural control of the (hydraulic) permeability, which affects the melt-season albedo (shortwave reflectance) of sea ice by enabling or restricting the drainage of surface meltwater, and is also relevant for other processes including nutrient delivery to microorganisms colonizing the lower layers of the ice sheet. At low temperatures, the relative brine volume (porosity) is small, the inclusions are disconnected, and the permeability is small. The relative brine volume increases with temperature, and the permeability increases strongly above a porosity of ~5%. We have imaged the pore space of natural and laboratory-grown sea ice with x-ray micro-computed tomography (CT) over a temperature range typical of that in the Arctic ( - 25°C to -3°C) and which spans corresponding changes in the permeability by several orders of magnitude. Based on our `Dual Model' approach, we identify pore bodies and throats from the segmented CT data to eventually derive a pore network. We characterize the temperature-dependence of the pore space connectivity and apply critical path analysis to investigate the dependence of permeability on pore microstructural evolution.

  17. Micro-CT scan reveals an unexpected high-volume and interconnected pore network in a Cretaceous Sanagasta dinosaur eggshell.

    PubMed

    Hechenleitner, E Martín; Grellet-Tinner, Gerald; Foley, Matthew; Fiorelli, Lucas E; Thompson, Michael B

    2016-03-01

    The Cretaceous Sanagasta neosauropod nesting site (La Rioja, Argentina) was the first confirmed instance of extinct dinosaurs using geothermal-generated heat to incubate their eggs. The nesting strategy and hydrothermal activities at this site led to the conclusion that the surprisingly 7 mm thick-shelled eggs were adapted to harsh hydrothermal microenvironments. We used micro-CT scans in this study to obtain the first three-dimensional microcharacterization of these eggshells. Micro-CT-based analyses provide a robust assessment of gas conductance in fossil dinosaur eggshells with complex pore canal systems, allowing calculation, for the first time, of the shell conductance through its thickness. This novel approach suggests that the shell conductance could have risen during incubation to seven times more than previously estimated as the eggshell erodes. In addition, micro-CT observations reveal that the constant widening and branching of pore canals form a complex funnel-like pore canal system. Furthermore, the high density of pore canals and the presence of a lateral canal network in the shell reduce the risks of pore obstruction during the extended incubation of these eggs in a relatively highly humid and muddy nesting environment. PMID:27009182

  18. Simulating the Gas Diffusion Coefficient in Macropore Network Images: Influences of Soil Pore Morphology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of the diffusion coefficient is necessary for modeling gas transport in soils and other porous media. This study was conducted to determine the relationship between the diffusion coefficient and pore structure parameters, such as the fractal dimension of pores (Dmp), the shortest path leng...

  19. 3d-3d correspondence revisited

    NASA Astrophysics Data System (ADS)

    Chung, Hee-Joong; Dimofte, Tudor; Gukov, Sergei; Sułkowski, Piotr

    2016-04-01

    In fivebrane compactifications on 3-manifolds, we point out the importance of all flat connections in the proper definition of the effective 3d {N}=2 theory. The Lagrangians of some theories with the desired properties can be constructed with the help of homological knot invariants that categorify colored Jones polynomials. Higgsing the full 3d theories constructed this way recovers theories found previously by Dimofte-Gaiotto-Gukov. We also consider the cutting and gluing of 3-manifolds along smooth boundaries and the role played by all flat connections in this operation.

  20. Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure.

    PubMed

    Grate, Jay W; Kelly, Ryan T; Suter, Jonathan; Anheier, Norm C

    2012-11-21

    Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water-wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen-sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges of oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain defined spatial structure in the sensor image. PMID:22995983

  1. Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure

    SciTech Connect

    Grate, Jay W.; Kelly, Ryan T.; Suter, Jonathan D.; Anheier, Norman C.

    2012-11-21

    Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The micromodel can be imaged from either side. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges dissolved oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain spatial information in the sensor image.

  2. Remote 3D Medical Consultation

    NASA Astrophysics Data System (ADS)

    Welch, Greg; Sonnenwald, Diane H.; Fuchs, Henry; Cairns, Bruce; Mayer-Patel, Ketan; Yang, Ruigang; State, Andrei; Towles, Herman; Ilie, Adrian; Krishnan, Srinivas; Söderholm, Hanna M.

    Two-dimensional (2D) video-based telemedical consultation has been explored widely in the past 15-20 years. Two issues that seem to arise in most relevant case studies are the difficulty associated with obtaining the desired 2D camera views, and poor depth perception. To address these problems we are exploring the use of a small array of cameras to synthesize a spatially continuous range of dynamic three-dimensional (3D) views of a remote environment and events. The 3D views can be sent across wired or wireless networks to remote viewers with fixed displays or mobile devices such as a personal digital assistant (PDA). The viewpoints could be specified manually or automatically via user head or PDA tracking, giving the remote viewer virtual head- or hand-slaved (PDA-based) remote cameras for mono or stereo viewing. We call this idea remote 3D medical consultation (3DMC). In this article we motivate and explain the vision for 3D medical consultation; we describe the relevant computer vision/graphics, display, and networking research; we present a proof-of-concept prototype system; and we present some early experimental results supporting the general hypothesis that 3D remote medical consultation could offer benefits over conventional 2D televideo.

  3. Strong and fast-recovery organic/inorganic hybrid AuNPs-supramolecular gels based on loofah-like 3D networks.

    PubMed

    He, Huiwen; Chen, Si; Tong, Xiaoqian; Chen, Yining; Wu, Bozhen; Ma, Meng; Wang, Xiaosong; Wang, Xu

    2016-01-21

    Super strong and fast-recovery organic/inorganic hybrid gold nanoparticle (AuNPs)-supramolecular gels based on a three-dimensional loofah-like nanoscale network self-assembled by polyhedral oligomeric silsesquioxane (POSS) core supramolecular gelators are reported for the first time. Two series of POSS core organic/inorganic hybrid gelators, POSS-BOC-l-Homophenylalanine (POSS-Hpy) and POSS-Boc-Cys(Bzl)-OH (POSS-Cys), with two types of peripherals having different abilities for driving the self-assembly of AuNPs in gels were designed and synthesized, both of which self-assembled into three-dimensional loofah-like nanoscale gel networks producing hybrid physical gels with fast-recovery behaviors. The mechanical properties of the resultant hybrid gels were dramatically increased by as much as 100 times in the system of sulfur containing POSS-Cys gelators without destroying the fast-recovery behaviors, with the addition of AuNPs, which had direct interaction with AuNPs to give S-Au non-covalent driving force to lead AuNPs self-assemble onto the 3D loofah-like network nanofibres in the supramolecular hybrid gel system. However, in the POSS-Hpy gelator system without sulfur, no strong interaction with AuNPs existed and the POSS-Hpy nanocomposites showed no clear changes in morphology, thermal stability or rheological properties, confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), tube-inversion and rotational rheometer measurements. This indicated that the organic/inorganic hybrid gelator POSS-Cys could be applied to the formation of soft materials in which AuNPs were self-assembled and closely arranged into three-dimensional nanoscale networks. This hybrid material has great potential for applications in self-recovery, nano- and micron-scale electronic devices, because it has both a large mechanical strength and a fast-recovery capability. PMID:26568047

  4. Tuning Pore Size in Square-Lattice Coordination Networks for Size-Selective Sieving of CO2.

    PubMed

    Chen, Kai-Jie; Madden, David G; Pham, Tony; Forrest, Katherine A; Kumar, Amrit; Yang, Qing-Yuan; Xue, Wei; Space, Brian; Perry, John J; Zhang, Jie-Peng; Chen, Xiao-Ming; Zaworotko, Michael J

    2016-08-22

    Porous materials capable of selectively capturing CO2 from flue-gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size-exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore-size in a coordination network, [Cu(quinoline-5-carboxyate)2 ]n (Qc-5-Cu) ena+bles ultra-high selectivity for CO2 over N2 (SCN ≈40 000) and CH4 (SCM ≈3300). Qc-5-Cu-sql-β, a narrow pore polymorph of the square lattice (sql) coordination network Qc-5-Cu-sql-α, adsorbs CO2 while excluding both CH4 and N2 . Experimental measurements and molecular modeling validate and explain the performance. Qc-5-Cu-sql-β is stable to moisture and its separation performance is unaffected by humidity. PMID:27439315

  5. Dual simulations of fluid flow and seismic wave propagation in a fractured network: effects of pore pressure on seismic signature

    NASA Astrophysics Data System (ADS)

    Vlastos, S.; Liu, E.; Main, I. G.; Schoenberg, M.; Narteau, C.; Li, X. Y.; Maillot, B.

    2006-08-01

    Fluid flow in the Earth's crust plays an important role in a number of geological processes. In relatively tight rock formations such flow is usually controlled by open macrofractures, with significant implications for ground water flow and hydrocarbon reservoir management. The movement of fluids in the fractured media will result in changes in the pore pressure and consequently will cause changes to the effective stress, traction and elastic properties. The main purpose of this study is to numerically examine the effect of pore pressure changes on seismic wave propagation (i.e. the effects of pore pressures on amplitude, arrival time, frequency content). This is achieved by using dual simulations of fluid flow and seismic propagation in a common 2-D fracture network. Note that the dual simulations are performed separately as the coupled simulations of fluid flow and seismic wave propagations in such fracture network is not possible because the timescales of fluid flow and wave propagation are considerably different (typically, fluid flows in hours, whereas wave propagation in seconds). The flow simulation updates the pore pressure at consecutive time steps, and thus the elastic properties of the rock, for the seismic modelling. In other words, during each time step of the flow simulations, we compute the elastic response corresponding to the pore pressure distribution. The relationship between pore pressure and fractures is linked via an empirical relationship given by Schoenberg and the elastic response of fractures is computed using the equivalent medium theory described by Hudson and Liu. Therefore, we can evaluate the possibility of inferring the changes of fluid properties directly from seismic data. Our results indicate that P waves are not as sensitive to pore pressure changes as S and coda (or scattered) waves. The increase in pore pressure causes a shift of the energy towards lower frequencies, as shown from the spectrum (as a result of scattering

  6. 3D Networked Tin Oxide/Graphene Aerogel with a Hierarchically Porous Architecture for High-Rate Performance Sodium-Ion Batteries.

    PubMed

    Xie, Xiuqiang; Chen, Shuangqiang; Sun, Bing; Wang, Chengyin; Wang, Guoxiu

    2015-09-01

    Low-cost and sustainable sodium-ion batteries are regarded as a promising technology for large-scale energy storage and conversion. The development of high-rate anode materials is highly desirable for sodium-ion batteries. The optimization of mass transport and electron transfer is crucial in the discovery of electrode materials with good high-rate performances. Herein, we report the synthesis of 3 D interconnected SnO2 /graphene aerogels with a hierarchically porous structure as anode materials for sodium-ion batteries. The unique 3 D architecture was prepared by a facile in situ process, during which cross-linked 3 D conductive graphene networks with macro-/meso-sized hierarchical pores were formed and SnO2 nanoparticles were dispersed uniformly on the graphene surface simultaneously. Such a 3 D functional architecture not only facilitates the electrode-electrolyte interaction but also provides an efficient electron pathway within the graphene networks. When applied as anode materials in sodium-ion batteries, the as-prepared SnO2 /graphene aerogel exhibited high reversible capacity, improved cycling performance compared to SnO2 , and promising high-rate capability. PMID:26079600

  7. Single-Crystal to Single-Crystal Phase Transition and Segmented Thermochromic Luminescence in a Dynamic 3D Interpenetrated Ag(I) Coordination Network.

    PubMed

    Yan, Zhi-Hao; Li, Xiao-Yu; Liu, Li-Wei; Yu, Si-Qi; Wang, Xing-Po; Sun, Di

    2016-02-01

    A new 3D Ag(I)-based coordination network, [Ag2(pz)(bdc)·H2O]n (1; pz = pyrazine and H2bdc = benzene-1,3-dicarboxylic acid), was constructed by one-pot assembly and structurally established by single-crystal X-ray diffraction at different temperatures. Upon cooling from 298 to 93 K, 1 undergo an interesting single-crystal to single-crystal phase transition from orthorhombic Ibca (Z = 16) to Pccn (Z = 32) at around 148 K. Both phases show a rare 2-fold-interpenetrated 4-connected lvt network but incorporate different [Ag2(COO)2] dimeric secondary building units. It is worth mentioning that complex 1 shows red- and blue-shifted luminescences in the 290-170 and 140-80 K temperature ranges, respectively. The variable-temperature single-crystal X-ray crystallographic studies suggest that the argentophilic interactions and rigidity of the structure dominated the luminescence chromism trends at the respective temperature ranges. Upon being mechanically ground, 1 exhibits a slight mechanoluminescence red shift from 589 to 604 nm at 298 K. PMID:26828950

  8. 3D and Education

    NASA Astrophysics Data System (ADS)

    Meulien Ohlmann, Odile

    2013-02-01

    Today the industry offers a chain of 3D products. Learning to "read" and to "create in 3D" becomes an issue of education of primary importance. 25 years professional experience in France, the United States and Germany, Odile Meulien set up a personal method of initiation to 3D creation that entails the spatial/temporal experience of the holographic visual. She will present some different tools and techniques used for this learning, their advantages and disadvantages, programs and issues of educational policies, constraints and expectations related to the development of new techniques for 3D imaging. Although the creation of display holograms is very much reduced compared to the creation of the 90ies, the holographic concept is spreading in all scientific, social, and artistic activities of our present time. She will also raise many questions: What means 3D? Is it communication? Is it perception? How the seeing and none seeing is interferes? What else has to be taken in consideration to communicate in 3D? How to handle the non visible relations of moving objects with subjects? Does this transform our model of exchange with others? What kind of interaction this has with our everyday life? Then come more practical questions: How to learn creating 3D visualization, to learn 3D grammar, 3D language, 3D thinking? What for? At what level? In which matter? for whom?

  9. A high-resolution 3D seismic velocity model of the 2010 Mw 8.8 Maule, Chile earthquake rupture zone using land & OBS networks

    NASA Astrophysics Data System (ADS)

    Hicks, S. P.; Rietbrock, A.; Ryder, I. M.; Miller, M.; Lee, C.

    2013-12-01

    Knowledge of seismic properties along a subduction megathrust can shed light on the composition and structure of rocks along the fault. By comparing seismic velocity structure with models of interseismic locking, co-seismic slip and afterslip, we can begin to understand how physical properties may affect fault dynamics throughout the subduction seismic cycle. The Maule earthquake, which hit the coast of central Chile in 2010, is the 6th largest earthquake ever recorded, rupturing a 500 x 80 km area of the Chilean megathrust. Published models demonstrate a complex bilateral rupture, with most co-seismic slip occurring to the north of the mainshock epicentre, although significant slip likely stopped short of the trench and the continental Moho. Here, we show a new high-resolution 3D velocity model (vp and vp/vs ratio) of the central Chilean margin Our velocity model is based on manually picked P- and S-wave arrival times from 670 aftershocks recorded by the International Maule Aftershock Deployment (IMAD) network. Seismic properties of the marine forearc are poorly understood in subduction zones, but by incorporating picks from two ocean-bottom seismometer (OBS) networks, we can resolve the velocity structure of the megathrust as far as the trench. In total, the catalogue used for the tomographic inversion yields a total of ~50,000 high quality P- and S-wave picks. We analyse the quality of our model by analysis of the resolution matrix and by testing characteristic models. The 3D velocity model shows the main structures associated within a subduction forearc: the marine forearc basin (vp < 6.0 km/s), continental mantle (vp > 7.5 km/s), and subducting oceanic crust (vp ~ 7.7 km/s). The plate interface is well defined by relocated aftershock seismicity. P-wave velocities along the megathrust range from 6.5 km/s beneath the marine forearc to 7.7 km/s at the intersection of the megathrust with the continental Moho. We infer several high vp anomalies within the South

  10. Porosity-controlled eggshell membrane as 3D SERS-active substrate.

    PubMed

    Lin, Pei-Ying; Hsieh, Chiung-Wen; Tsai, Pei-Chuan; Hsieh, Shuchen

    2014-06-01

    We report on the fabrication of a surface-enhanced Raman scattering (SERS) platform, comprised of a three-dimensional (3D) porous eggshell membrane (ESM) scaffold decorated with Ag nanoparticles (NPs). Both native and treated ESM were used, where the treated ESM pore size and fiber crossing density was controlled by timed exposure to hydrogen peroxide (H2O2). Ag NPs were synthesized in situ by reduction of silver nitrate with ascorbic acid. Our results demonstrate that H2O2-treated Ag-ESM provides a more densely packed 3D network of active material, which leads to consistently higher SERS enhancement than untreated Ag-ESM substrates. PMID:24590917

  11. 3D Imaging.

    ERIC Educational Resources Information Center

    Hastings, S. K.

    2002-01-01

    Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

  12. Individual 3D region-of-interest atlas of the human brain: automatic training point extraction for neural-network-based classification of brain tissue types

    NASA Astrophysics Data System (ADS)

    Wagenknecht, Gudrun; Kaiser, Hans-Juergen; Obladen, Thorsten; Sabri, Osama; Buell, Udalrich

    2000-04-01

    Individual region-of-interest atlas extraction consists of two main parts: T1-weighted MRI grayscale images are classified into brain tissues types (gray matter (GM), white matter (WM), cerebrospinal fluid (CSF), scalp/bone (SB), background (BG)), followed by class image analysis to define automatically meaningful ROIs (e.g., cerebellum, cerebral lobes, etc.). The purpose of this algorithm is the automatic detection of training points for neural network-based classification of brain tissue types. One transaxial slice of the patient data set is analyzed. Background separation is done by simple region growing. A random generator extracts spatially uniformly distributed training points of class BG from that region. For WM training point extraction (TPE), the homogeneity operator is the most important. The most homogeneous voxels define the region for WM TPE. They are extracted by analyzing the cumulative histogram of the homogeneity operator response. Assuming a Gaussian gray value distribution in WM, a random number is used as a probabilistic threshold for TPE. Similarly, non-white matter and non-background regions are analyzed for GM and CSF training points. For SB TPE, the distance from the BG region is an additional feature. Simulated and real 3D MRI images are analyzed and error rates for TPE and classification calculated.

  13. Concerted Motions Networking Pores and Distant Ferroxidase Centers Enable Bacterioferritin Function and Iron Traffic£ξ

    PubMed Central

    Yao, Huili; Rui, Huan; Kumar, Ritesh; Eshelman, Kate; Lovell, Scott; Battaile, Kevin P.; Im, Wonpil; Rivera, Mario

    2015-01-01

    X-ray crystallography, molecular dynamics (MD) simulations and biochemistry were utilized to investigate the effect of introducing hydrophobic interactions in the 4-fold (N148L and Q151L) and B-pores (D34F) of Pseudomonas aeruginosa bacterioferritin B (BfrB) on BfrB function. The structures show only local structural perturbations and confirm the anticipated hydrophobic interactions. Surprisingly, structures obtained after soaking crystals in Fe2+-containing crystallization solution revealed that although iron loads into the ferroxidase centers of the mutants, the side chains of ferroxidase ligands E51 and H130 do not reorganize to bind the iron ions, as is seen in the wt BfrB structures. Similar experiments with a double mutant (C89S/K96C) prepared to introduce changes outside the pores show competent ferroxidase centers that function akin to those in wt BfrB. MD simulations comparing wt BfrB with the D34F and N148L mutants show that the mutants exhibit significantly reduced flexibility, and reveal a network of concerted motions linking ferroxidase centers and 4-fold and B-pores, which are important for imparting ferroxidase centers in BfrB with the required flexibility to function efficiently. In agreement, the efficiency of Fe2+ oxidation and uptake of the 4-fold and B-pore mutants in solution is significantly compromised relative to wt or C89S/K96C BfrB. Finally, our structures show a large number of previously unknown iron binding sites in the interior cavity and B-pores of BfrB, which reveal in unprecedented detail conduits followed by iron and phosphate ions across the BfrB shell, as well as paths in the interior cavity that may facilitate nucleation of the iron phosphate mineral. PMID:25640193

  14. Evaluation of two-phase relative permeability and capillary pressure relations for unstable displacements in a pore network

    SciTech Connect

    Dehoff, Karl J.; Oostrom, Martinus; Zhang, Changyong; Grate, Jay W.

    2012-10-29

    A series of displacement experiments was conducted using five wetting-nonwetting immiscible fluid pairs in a homogenous and uniform pore network. The micromodel was initially saturated with either polyethylene glycol 200 (PEG) or water as a wetting fluid, which was subsequently displaced by a nonwetting fluid (dodecane, hexadecane, or mineral oil) at different flow rates. The experiments were designed to allow determinations of nonwetting fluid relative permeabilities ( ), fluid saturations ( ), and capillary pressure heads ( ). In the displacements, nonwetting fluid saturations increased with increasing flow rates for all five fluid pairs, and viscous fingering, capillary fingering, and stable displacement were observed. Viscous fingering occurred when PEG was displaced by either dodecane or hexadecane. For the water displacements, capillary fingers were observed at low capillary numbers. Due to unstable fingering phenomena, values for the PEG displacements were smaller than for the water displacements. A fitting exercise using the Brooks-Corey (1964) relationship showed that the fitted entry pressure heads are reasonably close to the computed entry pressure head. The fitted pore geometry factor, Sn values for the displacements are considerably lower than what is expected for displacements in homogeneous, highly uniform, porous systems, demonstrating the impact of unstable displacement on the apparent value of Sn. It was shown that a continuum-based multiphase model could be used to predict the average behavior for wetting fluid drainage in a pore network as long as independently fitted - and - relations are used. The use of a coupled approach through the Brooks-Corey pore geometry factor underpredicts observed values.

  15. 3D-calibration of three- and four-sensor hot-film probes based on collocated sonic using neural networks

    NASA Astrophysics Data System (ADS)

    Kit, Eliezer; Liberzon, Dan

    2016-09-01

    High resolution measurements of turbulence in the atmospheric boundary layer (ABL) are critical to the understanding of physical processes and parameterization of important quantities, such as the turbulent kinetic energy dissipation. Low spatio-temporal resolution of standard atmospheric instruments, sonic anemometers and LIDARs, limits their suitability for fine-scale measurements of ABL. The use of miniature hot-films is an alternative technique, although such probes require frequent calibration, which is logistically untenable in field setups. Accurate and truthful calibration is crucial for the multi-hot-films applications in atmospheric studies, because the ability to conduct calibration in situ ultimately determines the turbulence measurements quality. Kit et al (2010 J. Atmos. Ocean. Technol. 27 23–41) described a novel methodology for calibration of hot-film probes using a collocated sonic anemometer combined with a neural network (NN) approach. An important step in the algorithm is the generation of a calibration set for NN training by an appropriate low-pass filtering of the high resolution voltages, measured by the hot-film-sensors and low resolution velocities acquired by the sonic. In Kit et al (2010 J. Atmos. Ocean. Technol. 27 23–41), Kit and Grits (2011 J. Atmos. Ocean. Technol. 28 104–10) and Vitkin et al (2014 Meas. Sci. Technol. 25 75801), the authors reported on successful use of this approach for in situ calibration, but also on the method’s limitations and restricted range of applicability. In their earlier work, a jet facility and a probe, comprised of two orthogonal x-hot-films, were used for calibration and for full dataset generation. In the current work, a comprehensive laboratory study of 3D-calibration of two multi-hot-film probes (triple- and four-sensor) using a grid flow was conducted. The probes were embedded in a collocated sonic, and their relative pitch and yaw orientation to the mean flow was changed by means of

  16. 3-D P-wave velocity structure and seismicity in Central Costa Rica from Local Earthquake Tomography using an amphibic network

    NASA Astrophysics Data System (ADS)

    Arroyo, I.; Husen, S.; Flueh, E.; Alvarado, G. E.

    2008-12-01

    The Central Pacific sector of the erosional margin in Costa Rica shows a high seismicity rate, coincident with the subduction of rough-relief ocean floor, and generates earthquakes up to Mw 7. Precise earthquake locations and detailed knowledge of the 3-D velocity structure provide key insights into the dynamics of subduction zones. To this end, we performed a 3-D Local Earthquake Tomography using P-wave traveltimes from 595 selected events recorded by a seismological network of off- and onshore stations, deployed for 6 months in the area. The results reflect the complexity associated to subduction of bathymetric highs and the transition from normal to thickened oceanic crust (Cocos Ridge). The slab is imaged as a high-velocity anomaly with a band of low velocities (LVB) on top enclosing the intraslab events deeper than ~30 km. Below the margin slope, the LVB is locally thickened by at least two seamounts. We observe an abrupt, eastward widening of the LVB, preceded by a low-velocity anomaly under the continental shelf, which we interpret as a big seamount. The thickening coincides with an inverted basin at the inner forearc and a low-velocity anomaly under it. The latter appears in a sector where blocks of inner forearc are uplifted, possibly by underplating of eroded material against the base of the crust. The anomaly promotes seismicity by high-friction with the upper plate, and could be linked to a Mw 6.4 earthquake in 2004. In the west part of the area, the interplate seismicity forms a cluster beneath the continental shelf. Its updip limit coincides with the 150° C isotherm and an increase in Vp along the plate boundary. This further supports a proposed model in which the seismicity onset along the plate interface is mainly due to a decrease in the abundance of the fluids released by subducted sediments. Higher seismicity rates locally concur with seamounts present at the seismogenic zone, while seamounts under the margin slope may shallow the onset of

  17. Real-time prediction and gating of respiratory motion in 3D space using extended Kalman filters and Gaussian process regression network.

    PubMed

    Bukhari, W; Hong, S-M

    2016-03-01

    The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the radiation treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting respiratory motion in 3D space and realizing a gating function without pre-specifying a particular phase of the patient's breathing cycle. The algorithm, named EKF-GPRN(+) , first employs an extended Kalman filter (EKF) independently along each coordinate to predict the respiratory motion and then uses a Gaussian process regression network (GPRN) to correct the prediction error of the EKF in 3D space. The GPRN is a nonparametric Bayesian algorithm for modeling input-dependent correlations between the output variables in multi-output regression. Inference in GPRN is intractable and we employ variational inference with mean field approximation to compute an approximate predictive mean and predictive covariance matrix. The approximate predictive mean is used to correct the prediction error of the EKF. The trace of the approximate predictive covariance matrix is utilized to capture the uncertainty in EKF-GPRN(+) prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification enables us to pause the treatment beam over such instances. EKF-GPRN(+) implements a gating function by using simple calculations based on the trace of the predictive covariance matrix. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPRN(+) . The experimental results show that the EKF-GPRN(+) algorithm reduces the patient-wise prediction error to 38%, 40% and 40% in root-mean-square, compared to no prediction, at lookahead lengths of 192 ms, 384 ms and 576 ms, respectively. The EKF-GPRN(+) algorithm can further reduce the prediction error by employing the gating

  18. Real-time prediction and gating of respiratory motion in 3D space using extended Kalman filters and Gaussian process regression network

    NASA Astrophysics Data System (ADS)

    Bukhari, W.; Hong, S.-M.

    2016-03-01

    The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the radiation treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting respiratory motion in 3D space and realizing a gating function without pre-specifying a particular phase of the patient’s breathing cycle. The algorithm, named EKF-GPRN+ , first employs an extended Kalman filter (EKF) independently along each coordinate to predict the respiratory motion and then uses a Gaussian process regression network (GPRN) to correct the prediction error of the EKF in 3D space. The GPRN is a nonparametric Bayesian algorithm for modeling input-dependent correlations between the output variables in multi-output regression. Inference in GPRN is intractable and we employ variational inference with mean field approximation to compute an approximate predictive mean and predictive covariance matrix. The approximate predictive mean is used to correct the prediction error of the EKF. The trace of the approximate predictive covariance matrix is utilized to capture the uncertainty in EKF-GPRN+ prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification enables us to pause the treatment beam over such instances. EKF-GPRN+ implements a gating function by using simple calculations based on the trace of the predictive covariance matrix. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPRN+ . The experimental results show that the EKF-GPRN+ algorithm reduces the patient-wise prediction error to 38%, 40% and 40% in root-mean-square, compared to no prediction, at lookahead lengths of 192 ms, 384 ms and 576 ms, respectively. The EKF-GPRN+ algorithm can further reduce the prediction error by employing the gating function, albeit

  19. Macroscopic Carbon Nanotube-based 3D Monoliths.

    PubMed

    Du, Ran; Zhao, Qiuchen; Zhang, Na; Zhang, Jin

    2015-07-15

    Carbon nanotubes (CNTs) are one of the most promising carbon allotropes with incredible diverse physicochemical properties, thereby enjoying continuous worldwide attention since their discovery about two decades ago. From the point of view of practical applications, assembling individual CNTs into macroscopic functional and high-performance materials is of paramount importance. For example, multiscaled CNT-based assemblies including 1D fibers, 2D films, and 3D monoliths have been developed. Among all of these, monolithic 3D CNT architectures with porous structures have attracted increasing interest in the last few years. In this form, theoretically all individual CNTs are well connected and fully expose their surfaces. These 3D architectures have huge specific surface areas, hierarchical pores, and interconnected conductive networks, resulting in enhanced mass/electron transport and countless accessible active sites for diverse applications (e.g. catalysis, capacitors, and sorption). More importantly, the monolithic form of 3D CNT assemblies can impart additional application potentials to materials, such as free-standing electrodes, sensors, and recyclable sorbents. However, scaling the properties of individual CNTs to 3D assemblies, improving use of the diverse, structure-dependent properties of CNTs, and increasing the performance-to-cost ratio are great unsolved challenges for their real commercialization. This review aims to provide a comprehensive introduction of this young and energetic field, i.e., CNT-based 3D monoliths, with a focus on the preparation principles, current synthetic methods, and typical applications. Opportunities and challenges in this field are also presented. PMID:25740457

  20. Pore Network Modeling and Synchrotron Imaging of Liquid Water in the Gas Diffusion Layer of Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Hinebaugh, James Thomas

    Polymer electrolyte membrane (PEM) fuel cells operate at levels of high humidity, leading to condensation throughout the cell components. The porous gas diffusion layer (GDL) must not become over-saturated with liquid water, due to its responsibility in providing diffusion pathways to and from the embedded catalyst sites. Due to the opaque and microscale nature of the GDL, a current challenge of the fuel cell industry is to identify the characteristics that make the GDL more or less robust against flooding. Modeling the system as a pore network is an attractive investigative strategy; however, for flooding simulations to provide meaningful material comparisons, accurate GDL topology and condensation distributions must be provided. The focus of this research is to provide the foundational tools with which to capture both of these requirements. The method of pore network modeling on topologically representative pore networks is demonstrated to describe flooding phenomena within GDL materials. A stochastic modeling algorithm is then developed to create pore spaces with the relevant features of GDL materials. Then, synchrotron based X-ray visualization experiments are developed and conducted to provide insight into condensation conditions. It was found that through-plane porosity distributions have significant effects on the GDL saturation levels. Some GDL manufacturing processes result in high porosity regions which are predicted to become heavily saturated with water if they are positioned between the condensation sites and the exhaust channels. Additionally, it was found that fiber diameter and the volume fraction of binding material applied to the GDL have significant impacts on the GDL heterogeneity and pore size distribution. Representative stochastic models must accurately describe these three material characteristics. In situ, dynamic liquid water behavior was visualized at the Canadian Light source, Inc. synchrotron using imaging and image processing

  1. TRACE 3-D documentation

    SciTech Connect

    Crandall, K.R.

    1987-08-01

    TRACE 3-D is an interactive beam-dynamics program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined transport system. TRACE 3-D provides an immediate graphics display of the envelopes and the phase-space ellipses and allows nine types of beam-matching options. This report describes the beam-dynamics calculations and gives detailed instruction for using the code. Several examples are described in detail.

  2. Encapsulated discrete octameric water cluster, 1D water tape, and 3D water aggregate network in diverse MOFs based on bisimidazolium ligands

    NASA Astrophysics Data System (ADS)

    Shi, Ruo-Bing; Pi, Min; Jiang, Shuang-Shuang; Wang, Yuan-Yuan; Jin, Chuan-Ming

    2014-08-01

    Four new metal-organic frameworks, [Zn(2-mBIM)2(SO3CF3)2·(H2O)4] (1), [Zn(BMIE)(1,4-BDC)]·(H2O)3 (2), [Cd(BIM)2(OH)(H2O)2(PF6)]·(H2O)4 (3), and [Cd(PA-BIM)2 (ClO4)2]·11.33H2O (4) (2-mBIM = bis(2-methylimidazol-1-yl)methane, BMIE = 1,2-bis[1-(2-methylimidazole)-diethoxy]ethane, BIM = bis(imidazol-1-yl)methane, and PA-BIM = 1,1-bis [(2-phenylazo)imidazol-1-yl]methane) have been prepared and structurally characterized. Complex 1 exhibits an infinite 1D cationic beaded-chain structure, which encapsulated discrete octameric water clusters that are comprised of a chair-like hexameric water cluster with two extra water molecules dangling on two diagonal vertices of the chair. Complex 2 forms a 1D infinite zigzag metal-organic chain structure with a 1D T4(0)A(4) water tape. Complexes 3 show a 2D grid-like sheet structure with the 1D water tape T4(0)A(0)2(0) motif. Complex 4 is a porous 3D MOF with tetrahedron-coordinated Cd(II) centers and trans-conformation PA-BIM ligands. These holes are occupied by a fascinating three-dimensional water clathrate network, which consists of cage-shaped structural tetradecameric water cluster (H2O)14 units and six independent bridged water molecules. The results suggest that the bisimidazolium ligands and anions play crucial roles in the formation of the different host structures and different guest water aggregations. Additionally, the thermal stabilities and photoluminescence spectra of the complexes have been discussed.

  3. A functional relation for field-scale nonaqueous phase liquid dissolution developed using a pore network model

    USGS Publications Warehouse

    Dillard, L.A.; Essaid, H.I.; Blunt, M.J.

    2001-01-01

    A pore network model with cubic chambers and rectangular tubes was used to estimate the nonaqueous phase liquid (NAPL) dissolution rate coefficient, Kdissai, and NAPL/water total specific interfacial area, ai. Kdissai was computed as a function of modified Peclet number (Pe???) for various NAPL saturations (SN) and ai during drainage and imbibition and during dissolution without displacement. The largest contributor to ai was the interfacial area in the water-filled corners of chambers and tubes containing NAPL. When Kdissai was divided by ai, the resulting curves of dissolution coefficient, Kdiss versus Pe??? suggested that an approximate value of Kdiss could be obtained as a weak function of hysteresis or SN. Spatially and temporally variable maps of Kdissai calculated using the network model were used in field-scale simulations of NAPL dissolution. These simulations were compared to simulations using a constant value of Kdissai and the empirical correlation of Powers et al. [Water Resour. Res. 30(2) (1994b) 321]. Overall, a methodology was developed for incorporating pore-scale processes into field-scale prediction of NAPL dissolution. Copyright ?? 2001 .

  4. Number of microstates and configurational entropy for steady-state two-phase flows in pore networks

    NASA Astrophysics Data System (ADS)

    Daras, T.; Valavanides, M. S.

    2015-01-01

    Steady-state two-phase flow in porous media is a process whereby a wetting phase displaces a non-wetting phase within a pore network. It is a stationary, off equilibrium process -in the sense that it is maintained in dynamic equilibrium on the expense of energy supplied to the system. The efficiency of the process depends on its spontaneity, measurable by the rate of global entropy production. The latter has been proposed to comprise two components: the rate of mechanical energy dissipation at constant temperature (a thermal entropy component, Q/T, in the continuum mechanics scale) and a configurational entropy production component (a Boltzmann-type statistical-entropy component, klnW), due to the existence of a canonical ensemble of flow configurations, physically admissible to the externally imposed macrostate stationary conditions. Here, the number of microstates, lnW, in steady-state two-phase flows in pore networks is estimated in three stages: Combinatorics are implemented to evaluate the number of identified microstates per physically admissible internal flow arrangement compatible with the imposed stationary flow conditions. Then, "Stirling's approximation limiting procedure" is applied to downscale the computational effort associated with the operations between large factorial numbers. Finally, the number of microstates is estimated by contriving a limiting procedure over the canonical ensemble of the physically admissible flow configurations. Counting the microstates is a prerequisite for estimating the process configurational entropy in order to implement the Maximum Entropy Production principle and justify the existence of optimum operating conditions.

  5. Radiochromic 3D Detectors

    NASA Astrophysics Data System (ADS)

    Oldham, Mark

    2015-01-01

    Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.

  6. Bootstrapping 3D fermions

    NASA Astrophysics Data System (ADS)

    Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran

    2016-03-01

    We study the conformal bootstrap for a 4-point function of fermions < ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T . We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N . We also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  7. Geometric and Topological Analysis of Three-Dimensional Porous Media: Pore Space Partitioning Based on Morphological Skeletonization.

    PubMed

    Liang; Ioannidis; Chatzis

    2000-01-01

    This article presents a versatile, rigorous, and efficient methodology for extracting various geometric and topological parameters of 3D discrete porous media. The new approach takes advantage of the morphological skeleton of the pore structure-a lower dimensional representation of the pore space akin to the topological "deformation retract". The skeleton is derived by a fully parallel thinning algorithm that fulfils two essential requirements: it generates a medial axis and preserves the connectivity of the pore space. Topological analysis is accomplished by classifying all skeleton points as node or link (branch) points according to the concept of lambda-adjacency in 3D discrete space. In this manner, node coordination number and link length distributions are directly obtained from the skeleton. Pore necks (throats) are identified through a search for minima in the hydraulic radius of individual pore space channels outlined by skeleton links. In addition to the determination of the size distribution of the constrictions (pore necks) that control nonwetting phase invasion, improved estimates of the distributions of effective hydraulic and electric conductivity of individual pore space channels are obtained. Furthermore, erection of planes at the location of pore necks results in partitioning of the pore space into its constituent pores. This enables the characterization of the pore space in terms of a pore volume distribution. The new methodology is illustrated by application to a regular cubic pore network and irregularly shaped 2D and 3D pore networks generated by stochastic simulation. In the latter case, important new results are obtained concerning the sensitivity of geometric and topological properties of the microstructure to the parameters of stochastic simulation, namely, the porosity and correlation function. It is found that model porous media reconstructed from the same porosity and correlation function can exhibit marked differences in geometry and

  8. 3D-printing of undisturbed soil imaged by X-ray

    NASA Astrophysics Data System (ADS)

    Bacher, Matthias; Koestel, John; Schwen, Andreas

    2014-05-01

    The unique pore structures in Soils are altered easily by water flow. Each sample has a different morphology and the results of repetitions vary as well. Soil macropores in 3D-printed durable material avoid erosion and have a known morphology. Therefore potential and limitations of reproducing an undisturbed soil sample by 3D-printing was evaluated. We scanned an undisturbed soil column of Ultuna clay soil with a diameter of 7 cm by micro X-ray computer tomography at a resolution of 51 micron. A subsample cube of 2.03 cm length with connected macropores was cut out from this 3D-image and printed in five different materials by a 3D-printing service provider. The materials were ABS, Alumide, High Detail Resin, Polyamide and Prime Grey. The five print-outs of the subsample were tested on their hydraulic conductivity by using the falling head method. The hydrophobicity was tested by an adapted sessile drop method. To determine the morphology of the print-outs and compare it to the real soil also the print-outs were scanned by X-ray. The images were analysed with the open source program ImageJ. The five 3D-image print-outs copied from the subsample of the soil column were compared by means of their macropore network connectivity, porosity, surface volume, tortuosity and skeleton. The comparison of pore morphology between the real soil and the print-outs showed that Polyamide reproduced the soil macropore structure best while Alumide print-out was the least detailed. Only the largest macropore was represented in all five print-outs. Printing residual material or printing aid material remained in and clogged the pores of all print-out materials apart from Prime Grey. Therefore infiltration was blocked in these print-outs and the materials are not suitable even though the 3D-printed pore shapes were well reproduced. All of the investigated materials were insoluble. The sessile drop method showed angles between 53 and 85 degrees. Prime Grey had the fastest flow rate; the

  9. 3D Model of Melt Distribution in Partially Molten Dunite

    NASA Astrophysics Data System (ADS)

    Garapic, G.; Faul, U.; Brisson, E.

    2010-12-01

    The currently existing model of grain-scale melt geometry in the Earth’s upper mantle is derived from theoretical considerations that stem from material science research, combined with relatively low-resolution observations of polished two-dimensional surfaces. This model predicts a simple, interconnected network of melt along three-grain edges in static surface energy equilibrium. However, due to a continuous rearrangements of neighboring grains caused by grain growth, melt forms complex shapes among the grains. As a result, it is impossible to construct a 3D image of the pore space from 2D surfaces, which makes it particularly challenging to resolve the current controversy on whether all two-grain boundaries are wetted or melt-free. We present a new method for reconstruction of the 3D pore space in partially molten rocks. The method consists of serial sectioning and high resolution imaging (Field Emission SEM) of polished surfaces, followed by image alignment and rendering. The ablation rate during serial sectioning is determined by measuring the depth of a laser hole by interferometry. We removed a total of 25 layers with a spacing of of 1.3.microns between layers. Each layer consists of a mosaic of images approximately 300 x 320 microns in size. Melt regions are identified within each layer by hand-digitizing SEM images. We obtain a 3D model by stacking the slices, registering each slice, and using alpha shapes as a surface reconstruction technique. The sample we investigated is a partially molten dunite consisting of Fo90 olivine with a mean grain size of 33 microns and 4% melt. It was run in a piston cylinder at 1350°C and 1 GPa for 432 hours to achieve steady state grain growth. Rendering of the 3D pore space shows that the larger melt pockets at multi-grain junctions change within only a few microns in depth, whereas thin inclusions along two-grain boundaries persist over the entire depth of the imaged volume, which is similar to the mean grain size

  10. Dual FIB-SEM 3D Imaging and Lattice Boltzmann Modeling of Porosimetry and Multiphase Flow in Chalk

    NASA Astrophysics Data System (ADS)

    Rinehart, A. J.; Yoon, H.; Dewers, T. A.; Heath, J. E.; Petrusak, R.

    2010-12-01

    Mercury intrusion porosimetry (MIP) is an often-applied technique for determining pore throat distributions and seal analysis of fine-grained rocks. Due to closure effects, potential pore collapse, and complex pore network topologies, MIP data interpretation can be ambiguous, and often biased toward smaller pores in the distribution. We apply 3D imaging techniques and lattice-Boltzmann modeling in interpreting MIP data for samples of the Cretaceous Selma Group Chalk. In the Mississippi Interior Salt Basin, the Selma Chalk is the apparent seal for oil and gas fields in the underlying Eutaw Fm., and, where unfractured, the Selma Chalk is one of the regional-scale seals identified by the Southeast Regional Carbon Sequestration Partnership for CO2 injection sites. Dual focused ion - scanning electron beam and laser scanning confocal microscopy methods are used for 3D imaging of nanometer-to-micron scale microcrack and pore distributions in the Selma Chalk. A combination of image analysis software is used to obtain geometric pore body and throat distributions and other topological properties, which are compared to MIP results. 3D data sets of pore-microfracture networks are used in Lattice Boltzmann simulations of drainage (wetting fluid displaced by non-wetting fluid via the Shan-Chen algorithm), which in turn are used to model MIP procedures. Results are used in interpreting MIP results, understanding microfracture-matrix interaction during multiphase flow, and seal analysis for underground CO2 storage. This work was supported by the US Department of Energy, Office of Basic Energy Sciences as part of an Energy Frontier Research Center. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

  11. 3D microscope

    NASA Astrophysics Data System (ADS)

    Iizuka, Keigo

    2008-02-01

    In order to circumvent the fact that only one observer can view the image from a stereoscopic microscope, an attachment was devised for displaying the 3D microscopic image on a large LCD monitor for viewing by multiple observers in real time. The principle of operation, design, fabrication, and performance are presented, along with tolerance measurements relating to the properties of the cellophane half-wave plate used in the design.

  12. Three 3D hybrid networks based on octamolybdates and different Cu{sup I}/Cu{sup II}-bis(triazole) motifs

    SciTech Connect

    Zhang, Chun-Jing; Pang, Hai-Jun; Tang, Qun; Wang, Hui-Yuan; Chen, Ya-Guang

    2010-12-15

    Three 3D compounds based on octamolybdate clusters and various Cu{sup I}/Cu{sup II}-bis(triazole) motifs, [Cu{sup I}{sub 2}btb][{beta}-Mo{sub 8}O{sub 26}]{sub 0.5} (1), [Cu{sup I}{sub 2}btpe][{beta}-Mo{sub 8}O{sub 26}]{sub 0.5} (2), and [Cu{sup II}(btpe){sub 2}][{beta}-Mo{sub 8}O{sub 26}]{sub 0.5} (3) [btb=1,4-bis(1,2,4-triazol-1-yl)butane, btpe=1,5-bis(1,2,4-triazol-1-yl)pentane], were isolated via tuning flexible ligand spacer length and metal coordination preferences. In 1, the copper(I)-btb motif is a one-dimensional (1D) chain which is further linked by hexadentate {beta}-[Mo{sub 8}O{sub 26}]{sup 4-} clusters via coordinating to Cu{sup I} cations giving a 3D structure. In 2, the copper(I)-btpe motif exhibits a 'stairs'-like [Cu{sup I}{sub 2}btpe]{sup 2+} sheet, and the tetradentate {beta}-[Mo{sub 8}O{sub 26}]{sup 4-} clusters interact with two neighboring [Cu{sup I}{sub 2}btpe]{sup 2+} sheets constructing a 3D framework. In 3, the copper(II)-btpe motif possesses a novel (2D{yields}3D) interdigitated structure, which is further connected by the tetradentate {beta}-[Mo{sub 8}O{sub 26}]{sup 4-} clusters forming a 3D framework. The thermal stability and luminescent properties of 1-3 are investigated in the solid state. -- Graphical abstract: Three 3D compounds based on {beta}-[Mo{sub 8}O{sub 26}]{sup 4-} clusters with different Cu{sup I}/Cu{sup II}-bis(triazole) motifs were synthesized by regularly tuning flexible ligand spacer length and metal coordination preferences. Display Omitted

  13. Experimental study on nonmonotonicity of capillary desaturation curves in a 2-D pore-network

    SciTech Connect

    Rodriquez de Castro, Antonio; Shokri, Nima; Karadimitriou, Nikolaos; Oostrom, Martinus; Joekar-Niasar, Vahid

    2015-10-28

    Immiscible displacement in a porous medium is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two-phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oils saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigate the CDC as influenced by the viscosity ratio. A comprehensive series of experiments using a high-resolution microscope and state-of-the-art micromodels were conducted. The CDCs were calculated and the effects of Ca and M on phase entrapments were quantified. The results show that CDCs are not necessarily monotonic for all M.

  14. Experimental study on nonmonotonicity of Capillary Desaturation Curves in a 2-D pore network

    NASA Astrophysics Data System (ADS)

    Rodríguez de Castro, Antonio; Shokri, Nima; Karadimitriou, Nikolaos; Oostrom, Mart; Joekar-Niasar, Vahid

    2015-10-01

    Immiscible displacement in porous media is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two-phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oil saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigated the CDC as influenced by the viscosity ratio. To do so, we have conducted a comprehensive series of experiments using a high-resolution microscope and state-of-art micromodels to investigate the dynamics and patterns of phase entrapment at different Ca and M. By postprocessing of the experimental high-resolution images, we calculated the CDC and quantified the effects of the Ca and M on the phase entrapment and number of blobs trapped in the micromodel and their size distributions during immiscible two-phase flow. Our results show that CDCs are not necessarily monotonic for all M, and the physical mechanisms causing this nonmonotonic behavior are discussed.

  15. Template-free synthesis of functional 3D BN architecture for removal of dyes from water.

    PubMed

    Liu, Dan; Lei, Weiwei; Qin, Si; Chen, Ying

    2014-01-01

    Three-dimensional (3D) architectures are of interest in applications in electronics, catalysis devices, sensors and adsorption materials. However, it is still a challenge to fabricate 3D BN architectures by a simple method. Here, we report the direct synthesis of 3D BN architectures by a simple thermal treatment process. A 3D BN architecture consists of an interconnected flexible network of nanosheets. The typical nitrogen adsorption/desorption results demonstrate that the specific surface area for the as-prepared samples is up to 1156 m(2) g(-1), and the total pore volume is about 1.17 cm(3) g(-1). The 3D BN architecture displays very high adsorption rates and large capacities for organic dyes in water without any other additives due to its low densities, high resistance to oxidation, good chemical inertness and high surface area. Importantly, 88% of the starting adsorption capacity is maintained after 15 cycles. These results indicate that the 3D BN architecture is potential environmental materials for water purification and treatment. PMID:24663292

  16. Multiviewer 3D monitor

    NASA Astrophysics Data System (ADS)

    Kostrzewski, Andrew A.; Aye, Tin M.; Kim, Dai Hyun; Esterkin, Vladimir; Savant, Gajendra D.

    1998-09-01

    Physical Optics Corporation has developed an advanced 3-D virtual reality system for use with simulation tools for training technical and military personnel. This system avoids such drawbacks of other virtual reality (VR) systems as eye fatigue, headaches, and alignment for each viewer, all of which are due to the need to wear special VR goggles. The new system is based on direct viewing of an interactive environment. This innovative holographic multiplexed screen technology makes it unnecessary for the viewer to wear special goggles.

  17. 3D Audio System

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Ames Research Center research into virtual reality led to the development of the Convolvotron, a high speed digital audio processing system that delivers three-dimensional sound over headphones. It consists of a two-card set designed for use with a personal computer. The Convolvotron's primary application is presentation of 3D audio signals over headphones. Four independent sound sources are filtered with large time-varying filters that compensate for motion. The perceived location of the sound remains constant. Possible applications are in air traffic control towers or airplane cockpits, hearing and perception research and virtual reality development.

  18. Regional geothermal 3D modelling in Denmark

    NASA Astrophysics Data System (ADS)

    Poulsen, S. E.; Balling, N.; Bording, T. S.; Nielsen, S. B.

    2012-04-01

    In the pursuit of sustainable and low carbon emission energy sources, increased global attention has been given to the exploration and exploitation of geothermal resources within recent decades. In 2009 a national multi-disciplinary geothermal research project was established. As a significant part of this project, 3D temperature modelling is to be carried out, with special emphasis on temperatures of potential geothermal reservoirs in the Danish area. The Danish subsurface encompasses low enthalpy geothermal reservoirs of mainly Triassic and Jurassic age. Geothermal plants at Amager (Copenhagen) and Thisted (Northern Jutland) have the capacity of supplying the district heating network with up to 14 MW and 7 MW, respectively, by withdrawing warm pore water from the Gassum (Lower Jurassic/Upper Triassic) and Bunter (Lower Triassic) sandstone reservoirs, respectively. Explorative studies of the subsurface temperature regime typically are based on a combination of observations and modelling. In this study, the open-source groundwater modelling code MODFLOW is modified to simulate the subsurface temperature distribution in three dimensions by taking advantage of the mathematical similarity between saturated groundwater flow (Darcy flow) and heat conduction. A numerical model of the subsurface geology in Denmark is built and parameterized from lithological information derived from joint interpretation of seismic surveys and borehole information. Boundary conditions are constructed from knowledge about the heat flow from the Earth's interior and the shallow ground temperature. Matrix thermal conductivities have been estimated from analysis of high-resolution temperature logs measured in deep wells and porosity-depth relations are included using interpreted main lithologies. The model takes into account the dependency of temperature and pressure on thermal conductivity. Moreover, a transient model based correction of the paleoclimatic thermal disturbance caused by the

  19. 3D Surgical Simulation

    PubMed Central

    Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael

    2009-01-01

    This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308

  20. Reconstruction of 3D structure using stochastic methods: morphology and transport properties

    NASA Astrophysics Data System (ADS)

    Karsanina, Marina; Gerke, Kirill; Čapek, Pavel; Vasilyev, Roman; Korost, Dmitry; Skvortsova, Elena

    2013-04-01

    One of the main factors defining numerous flow phenomena in rocks, soils and other porous media, including fluid and solute movements, is pore structure, e.g., pore sizes and their connectivity. Numerous numerical methods were developed to quantify single and multi-phase flow in such media on microscale. Among most popular ones are: 1) a wide range of finite difference/element/volume solutions of Navier-Stokes equations and its simplifications; 2) lattice-Boltzmann method; 3) pore-network models, among others. Each method has some advantages and shortcomings, so that different research teams usually utilize more than one, depending on the study case. Recent progress in 3D imaging of internal structure, e.g., X-ray tomography, FIB-SEM and confocal microscopy, made it possible to obtain digitized input pore parameters for such models, however, a trade-off between resolution and sample size is usually unavoidable. There are situations then only standard two-dimensional information of porous structure is known due to tomography high cost or resolution limitations. However, physical modeling on microscale requires 3D information. There are three main approaches to reconstruct (using 2D cut(s) or some other limited information/properties) porous media: 1) statistical methods (correlation functions and simulated annealing, multi-point statistics, entropy methods), 2) sequential methods (sphere or other granular packs) and 3) morphological methods. Stochastic reconstructions using correlation functions possess some important advantage - they provide a statistical description of the structure, which is known to have relationships with all physical properties. In addition, this method is more flexible for other applications to characterize porous media. Taking different 3D scans of natural and artificial porous materials (sandstones, soils, shales, ceramics) we choose some 2D cut/s as sources of input correlation functions. Based on different types of correlation functions

  1. A FUNCTIONAL RELATION FOR FIELD-SCALE NONAQUEOUS PHASE LIQUID DISSOLUTION DEVELOPED USING A PORE NETWORK MODEL. (R825689C080)

    EPA Science Inventory

    Abstract

    A pore network model with cubic chambers and rectangular tubes was used to estimate the nonaqueous phase liquid (NAPL) dissolution rate coefficient, Kdissai, and NAPL/water total specific interfacial area, ai

  2. A FUNCTIONAL RELATION FOR FIELD-SCALE NONAQUEOUS PHASE LIQUID DISSOLUTION DEVELOPED USING A PORE NETWORK MODEL. (R825689C079)

    EPA Science Inventory

    Abstract

    A pore network model with cubic chambers and rectangular tubes was used to estimate the nonaqueous phase liquid (NAPL) dissolution rate coefficient, Kdissai, and NAPL/water total specific interfacial area, ai

  3. Large-Pore Mesoporous Silica with Three-Dimensional Wormhole Framework Structures.

    PubMed

    Park, In; Pinnavaia, Thomas J

    2009-02-01

    Large-pore mesoporous silica with 3D wormhole framework structures (denoted MSU-J) are prepared through a supramolecular hydrogen-bonding assembly pathway from low-cost sodium silicate as the silica source and commercially available mono- and triamine Jeffamine and Surfonamine surfactants as structure-directing porogens. The calcined mesostructures exhibit large pore sizes (up to 8.2 nm), surface areas (632-1030 m(2)/g) and pore volumes (0.5-2.0 cm(3)/g), depending on the surfactant chain length and synthesis temperature (25-65 °C). The textural properties of these new wormhole mesostructures are comparable to those of hexagonal SBA-15 derivatives and large pore MCM-48. However, unlike the SBA-15 structure type, wherein the 3D pore network is formed by connecting 1D cylindrical mesopores through micropores, MSU-J mesophases have wormhole framework structures containing fully interconnected 3D mesopores that can minimize the diffusion limitations often encountered in adsorption and chemical catalysis. Also, unlike large pore MCM-48, which requires cost-intensive tetraethylorthosilicate as a silica source and the use of a co-surfactant as a pore expander under strong acid conditions, MSU-J mesostructures are assembled from low cost sodium silicate in the presence of a single Jeffamine or Surfonamine porogen at near-neutral pH. PMID:20126285

  4. Biomass Growth and Clogging in Porous Media: From Microscale and Mesoscale Observations in Silicon Pore Imaging Elements to the Modeling of Aggregates in Network Models Using Material Mechanics

    NASA Astrophysics Data System (ADS)

    Dupin, H. J.; Mccarty, P. L.; Kitanidis, P. K.

    2002-05-01

    An apparatus for non-destructive continuous visualization of biological growth and clogging in porous media has been constructed. Silicon Pore Imaging Elements (micromodels featuring two-dimensional pore networks) were seeded with mixed cultures. A feed solution was then continuously forced through the SPIEs. Subsequently, several forms of biomass developped simultaneously: aggregates, biofilms and filaments ressembling mycellia. Clogging appeared mostly related to the presence of aggregates along preferential flow paths. Due to clogging, mesocale flow paths were modified, and flow was reversed in channels. A novel numerical model was then developped to investigate bioclogging of two-dimensional pore networks by aggregates. Each pore (channel) is seeded with initial biomass that consumes an electron donor and an electron acceptor according to dual Monod kinetics. Biomass is modeled as a continuous uniform isotropic hyperelastic material, whose expansion and deformation are governed by material mechanics stress-strain relations, unlike traditional approaches that use ad hoc empirical schemes. The Stokes flow, the advection-diffusion- reaction mass transport, and the biomass deformation partial differential equations are solved using finite elements. Simple networks are investigated to identify phenomena of interest: four channels of different width operating in parallel to study the effect of local heterogeneity; a periodic network to quantify the effects of distance from the injection point on clogging and substrate utilization; and square lattice 5 x 5 random width networks. Although square-lattice random-width networks are deemed better approximations of porous media, the simpler networks exhibit all the phenomena of interest, with the added advantage of these phenomena being decoupled. Results of numerical simulations for different network types under various boundary conditions show that aggregates have a far greater potential than biofilms to clog a porous

  5. 3D polarimetric purity

    NASA Astrophysics Data System (ADS)

    Gil, José J.; San José, Ignacio

    2010-11-01

    From our previous definition of the indices of polarimetric purity for 3D light beams [J.J. Gil, J.M. Correas, P.A. Melero and C. Ferreira, Monogr. Semin. Mat. G. de Galdeano 31, 161 (2004)], an analysis of their geometric and physical interpretation is presented. It is found that, in agreement with previous results, the first parameter is a measure of the degree of polarization, whereas the second parameter (called the degree of directionality) is a measure of the mean angular aperture of the direction of propagation of the corresponding light beam. This pair of invariant, non-dimensional, indices of polarimetric purity contains complete information about the polarimetric purity of a light beam. The overall degree of polarimetric purity is obtained as a weighted quadratic average of the degree of polarization and the degree of directionality.

  6. 3D field harmonics

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-03-30

    We have developed an harmonic representation for the three dimensional field components within the windings of accelerator magnets. The form by which the field is presented is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). The field components can be calculated with high precision and reduced cup time at any location (r,{theta},z) inside the magnet bore. The same conductor geometry which is used to simulate line currents is also used in CAD with modifications more readily available. It is our hope that the format used here for magnetic fields can be used not only as a means of delivering fields but also as a way by which beam dynamics can suggest correction to the conductor geometry. 5 refs., 70 figs.

  7. 'Bonneville' in 3-D!

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Mars Exploration Rover Spirit took this 3-D navigation camera mosaic of the crater called 'Bonneville' after driving approximately 13 meters (42.7 feet) to get a better vantage point. Spirit's current position is close enough to the edge to see the interior of the crater, but high enough and far enough back to get a view of all of the walls. Because scientists and rover controllers are so pleased with this location, they will stay here for at least two more martian days, or sols, to take high resolution panoramic camera images of 'Bonneville' in its entirety. Just above the far crater rim, on the left side, is the rover's heatshield, which is visible as a tiny reflective speck.

  8. Salinity effects on cracking morphology and dynamics in 3-D desiccating clays

    NASA Astrophysics Data System (ADS)

    DeCarlo, Keita F.; Shokri, Nima

    2014-04-01

    Saline conditions induce not only chemical but physical changes in swelling clays, and have a significant influence on the crack dynamics and morphology of desiccating clays. In this study, we used X-ray microtomography to experimentally investigate the effects of sodium chloride on the morphology and dynamics of desiccation cracks in three-dimensional mixtures of sand-bentonite slurry under varying rheological conditions. Rectangular glass containers were packed with slurries of different salt concentrations, with the top boundary exposed to air for evaporation. The growth and propagation of the cracking network that subsequently formed was visualized in 3-D at multiple intervals. The characterization of cracking and branching behavior shows a high extent of localized surficial crack networks at low salinity, with a transition to less extensive but more centralized crack networks with increased salinity. The observed behavior was described in the context of the physicochemical properties of the montmorillonite clay, where shifts from an "entangled" (large platelet spacing, small pore structure) to a "stacked" (small platelet spacing, open pore structure) network influence fluid distribution and thus extent of cracking and branching behavior. This is further corroborated by vertical profiles of water distribution, which shows localized desiccation fronts that shift to uniform desaturation with increasing salt concentration. Our results provide new insights regarding the formation, dynamics, and patterns of desiccation cracks formed during evaporation from 3-D saline clay structures, which will be useful in hydrological applications including water management, land surface evaporation, and subsurface contaminant transport.

  9. Scoops3D: software to analyze 3D slope stability throughout a digital landscape

    USGS Publications Warehouse

    Reid, Mark E.; Christian, Sarah B.; Brien, Dianne L.; Henderson, Scott T.

    2015-01-01

    The computer program, Scoops3D, evaluates slope stability throughout a digital landscape represented by a digital elevation model (DEM). The program uses a three-dimensional (3D) method of columns approach to assess the stability of many (typically millions) potential landslides within a user-defined size range. For each potential landslide (or failure), Scoops3D assesses the stability of a rotational, spherical slip surface encompassing many DEM cells using a 3D version of either Bishop’s simplified method or the Ordinary (Fellenius) method of limit-equilibrium analysis. Scoops3D has several options for the user to systematically and efficiently search throughout an entire DEM, thereby incorporating the effects of complex surface topography. In a thorough search, each DEM cell is included in multiple potential failures, and Scoops3D records the lowest stability (factor of safety) for each DEM cell, as well as the size (volume or area) associated with each of these potential landslides. It also determines the least-stable potential failure for the entire DEM. The user has a variety of options for building a 3D domain, including layers or full 3D distributions of strength and pore-water pressures, simplistic earthquake loading, and unsaturated suction conditions. Results from Scoops3D can be readily incorporated into a geographic information system (GIS) or other visualization software. This manual includes information on the theoretical basis for the slope-stability analysis, requirements for constructing and searching a 3D domain, a detailed operational guide (including step-by-step instructions for using the graphical user interface [GUI] software, Scoops3D-i) and input/output file specifications, practical considerations for conducting an analysis, results of verification tests, and multiple examples illustrating the capabilities of Scoops3D. Easy-to-use software installation packages are available for the Windows or Macintosh operating systems; these packages

  10. Objective assessment of the contribution of the RECOPESCA network to the monitoring of 3D coastal ocean variables in the Bay of Biscay and the English Channel

    NASA Astrophysics Data System (ADS)

    Lamouroux, Julien; Charria, Guillaume; De Mey, Pierre; Raynaud, Stéphane; Heyraud, Catherine; Craneguy, Philippe; Dumas, Franck; Le Hénaff, Matthieu

    2016-04-01

    In the Bay of Biscay and the English Channel, in situ observations represent a key element to monitor and to understand the wide range of processes in the coastal ocean and their direct impacts on human activities. An efficient way to measure the hydrological content of the water column over the main part of the continental shelf is to consider ships of opportunity as the surface to cover is wide and could be far from the coast. In the French observation strategy, the RECOPESCA programme, as a component of the High frequency Observation network for the environment in coastal SEAs (HOSEA), aims to collect environmental observations from sensors attached to fishing nets. In the present study, we assess that network using the Array Modes (ArM) method (a stochastic implementation of Le Hénaff et al. Ocean Dyn 59: 3-20. doi: 10.1007/s10236-008-0144-7, 2009). That model ensemble-based method is used here to compare model and observation errors and to quantitatively evaluate the performance of the observation network at detecting prior (model) uncertainties, based on hypotheses on error sources. A reference network, based on fishing vessel observations in 2008, is assessed using that method. Considering the various seasons, we show the efficiency of the network at detecting the main model uncertainties. Moreover, three scenarios, based on the reference network, a denser network in 2010 and a fictive network aggregated from a pluri-annual collection of profiles, are also analysed. Our sensitivity study shows the importance of the profile positions with respect to the sheer number of profiles for ensuring the ability of the network to describe the main error modes. More generally, we demonstrate the capacity of this method, with a low computational cost, to assess and to design new in situ observation networks.

  11. Spatially orthogonal chemical functionalization of a hierarchical pore network for catalytic cascade reactions

    NASA Astrophysics Data System (ADS)

    Parlett, Christopher M. A.; Isaacs, Mark A.; Beaumont, Simon K.; Bingham, Laura M.; Hondow, Nicole S.; Wilson, Karen; Lee, Adam F.

    2016-02-01

    The chemical functionality within porous architectures dictates their performance as heterogeneous catalysts; however, synthetic routes to control the spatial distribution of individual functions within porous solids are limited. Here we report the fabrication of spatially orthogonal bifunctional porous catalysts, through the stepwise template removal and chemical functionalization of an interconnected silica framework. Selective removal of polystyrene nanosphere templates from a lyotropic liquid crystal-templated silica sol-gel matrix, followed by extraction of the liquid crystal template, affords a hierarchical macroporous-mesoporous architecture. Decoupling of the individual template extractions allows independent functionalization of macropore and mesopore networks on the basis of chemical and/or size specificity. Spatial compartmentalization of, and directed molecular transport between, chemical functionalities affords control over the reaction sequence in catalytic cascades; herein illustrated by the Pd/Pt-catalysed oxidation of cinnamyl alcohol to cinnamic acid. We anticipate that our methodology will prompt further design of multifunctional materials comprising spatially compartmentalized functions.

  12. Three-dimensional mixed-wet random pore-scale network modeling of two- and three-phase flow in porous media. I. Model description

    NASA Astrophysics Data System (ADS)

    Piri, Mohammad; Blunt, Martin J.

    2005-02-01

    We present a three-dimensional network model to simulate two- and three-phase capillary dominated processes at the pore level. The displacement mechanisms incorporated in the model are based on the physics of multiphase flow observed in micromodel experiments. All the important features of immiscible fluid flow at the pore scale, such as wetting layers, spreading layers of the intermediate-wet phase, hysteresis, and wettability alteration are implemented in the model. Wettability alteration allows any values for the advancing and receding oil-water, gas-water, and gas-oil contact angles to be assigned. Multiple phases can be present in each pore or throat (element), in wetting and spreading layers, as well as occupying the center of the pore space. In all, some 30 different generic fluid configurations for two- and three-phase flow are analyzed. Double displacement and layer formation are implemented as well as direct two-phase displacement and layer collapse events. Every element has a circular, square, or triangular cross section. A random network that represents the pore space in Berea sandstone is used in this study. The model computes relative permeabilities, saturation paths, and capillary pressures for any displacement sequence. A methodology to track a given three-phase saturation path is presented that enables us to compare predicted and measured relative permeabilities on a point-by-point basis. A robust displacement-based clustering algorithm is also presented.

  13. Three-dimensional mixed-wet random pore-scale network modeling of two- and three-phase flow in porous media. I. Model description.

    PubMed

    Piri, Mohammad; Blunt, Martin J

    2005-02-01

    We present a three-dimensional network model to simulate two- and three-phase capillary dominated processes at the pore level. The displacement mechanisms incorporated in the model are based on the physics of multiphase flow observed in micromodel experiments. All the important features of immiscible fluid flow at the pore scale, such as wetting layers, spreading layers of the intermediate-wet phase, hysteresis, and wettability alteration are implemented in the model. Wettability alteration allows any values for the advancing and receding oil-water, gas-water, and gas-oil contact angles to be assigned. Multiple phases can be present in each pore or throat (element), in wetting and spreading layers, as well as occupying the center of the pore space. In all, some 30 different generic fluid configurations for two- and three-phase flow are analyzed. Double displacement and layer formation are implemented as well as direct two-phase displacement and layer collapse events. Every element has a circular, square, or triangular cross section. A random network that represents the pore space in Berea sandstone is used in this study. The model computes relative permeabilities, saturation paths, and capillary pressures for any displacement sequence. A methodology to track a given three-phase saturation path is presented that enables us to compare predicted and measured relative permeabilities on a point-by-point basis. A robust displacement-based clustering algorithm is also presented. PMID:15783413

  14. Fusion of multisensor passive and active 3D imagery

    NASA Astrophysics Data System (ADS)

    Fay, David A.; Verly, Jacques G.; Braun, Michael I.; Frost, Carl E.; Racamato, Joseph P.; Waxman, Allen M.

    2001-08-01

    We have extended our previous capabilities for fusion of multiple passive imaging sensors to now include 3D imagery obtained from a prototype flash ladar. Real-time fusion of low-light visible + uncooled LWIR + 3D LADAR, and SWIR + LWIR + 3D LADAR is demonstrated. Fused visualization is achieved by opponent-color neural networks for passive image fusion, which is then textured upon segmented object surfaces derived from the 3D data. An interactive viewer, coded in Java3D, is used to examine the 3D fused scene in stereo. Interactive designation, learning, recognition and search for targets, based on fused passive + 3D signatures, is achieved using Fuzzy ARTMAP neural networks with a Java-coded GUI. A client-server web-based architecture enables remote users to interact with fused 3D imagery via a wireless palmtop computer.

  15. 3D Soil Images Structure Quantification using Relative Entropy

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Gonzalez-Nieto, P. L.; Bird, N. R. A.

    2012-04-01

    Soil voids manifest the cumulative effect of local pedogenic processes and ultimately influence soil behavior - especially as it pertains to aeration and hydrophysical properties. Because of the relatively weak attenuation of X-rays by air, compared with liquids or solids, non-disruptive CT scanning has become a very attractive tool for generating three-dimensional imagery of soil voids. One of the main steps involved in this analysis is the thresholding required to transform the original (greyscale) images into the type of binary representation (e.g., pores in white, solids in black) needed for fractal analysis or simulation with Lattice-Boltzmann models (Baveye et al., 2010). The objective of the current work is to apply an innovative approach to quantifying soil voids and pore networks in original X-ray CT imagery using Relative Entropy (Bird et al., 2006; Tarquis et al., 2008). These will be illustrated using typical imagery representing contrasting soil structures. Particular attention will be given to the need to consider the full 3D context of the CT imagery, as well as scaling issues, in the application and interpretation of this index.

  16. The 2D versus 3D imaging trade-off: The impact of over- or under-estimating small throats for simulating permeability in porous media

    NASA Astrophysics Data System (ADS)

    Peters, C. A.; Crandell, L. E.; Um, W.; Jones, K. W.; Lindquist, W. B.

    2011-12-01

    Geochemical reactions in the subsurface can alter the porosity and permeability of a porous medium through mineral precipitation and dissolution. While effects on porosity are relatively well understood, changes in permeability are more difficult to estimate. In this work, pore-network modeling is used to estimate the permeability of a porous medium using pore and throat size distributions. These distributions can be determined from 2D Scanning Electron Microscopy (SEM) images of thin sections or from 3D X-ray Computed Tomography (CT) images of small cores. Each method has unique advantages as well as unique sources of error. 3D CT imaging has the advantage of reconstructing a 3D pore network without the inherent geometry-based biases of 2D images but is limited by resolutions around 1 μm. 2D SEM imaging has the advantage of higher resolution, and the ability to examine sub-grain scale variations in porosity and mineralogy, but is limited by the small size of the sample of pores that are quantified. A pore network model was created to estimate flow permeability in a sand-packed experimental column investigating reaction of sediments with caustic radioactive tank wastes in the context of the Hanford, WA site. Before, periodically during, and after reaction, 3D images of the porous medium in the column were produced using the X2B beam line facility at the National Synchrotron Light Source (NSLS) at Brookhaven National Lab. These images were interpreted using 3DMA-Rock to characterize the pore and throat size distributions. After completion of the experiment, the column was sectioned and imaged using 2D SEM in backscattered electron mode. The 2D images were interpreted using erosion-dilation to estimate the pore and throat size distributions. A bias correction was determined by comparison with the 3D image data. A special image processing method was developed to infer the pore space before reaction by digitally removing the precipitate. The different sets of pore

  17. Prominent rocks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. Wedge is at lower left; Shark, Half-Dome, and Pumpkin are at center. Flat Top, about four inches high, is at lower right. The horizon in the distance is one to two kilometers away.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  18. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  19. Gold Nanoparticle Synthesis by 3D Integrated Micro-solution Plasma in a 3D Printed Artificial Porous Dielectric Material

    NASA Astrophysics Data System (ADS)

    Sotoda, Naoya; Tanaka, Kenji; Shirafuji, Tatsuru

    2015-09-01

    Plasma in contact with HAuCl4 aqueous solution can promote the synthesis of gold nanoparticles. To scale up this process, we have developed 3D integrated micro-solution plasma (3D IMSP). It can generate a large number of argon microplasmas in contact with the aqueous solution flowing in a porous dielectric material. The porous dielectric material in our prototype 3D IMSP reactor, however, consists of non-regularly arranged random-sized pores. These pore parameters may be the parameters for controlling the size and dispersion of synthesized gold nanoparticles. We have hence fabricated a 3D IMSP reactor with an artificial porous dielectric material that has regularly arranged same-sized pores by using a 3D printer. We have applied the reactor to the gold- nanoparticle synthesis. We have confirmed the synthesis of gold nanoparticles through the observation of a plasmon resonance absorption peak at 550 nm in the HAuCl4 aqueous solution treated with 3D IMSP. The size and distribution of the synthesized gold nanoparticles are under investigation. We expect that these characteristics of the gold nanoparticles can be manipulated by changing pore size and their distribution in the porous dielectric material.

  20. Anionic 3D cage networks self-assembled by iodine and V-shaped pentaiodides using dimeric oxoammonium cations produced in situ as templates.

    PubMed

    Pang, Xue; Wang, Hui; Zhao, Xiao Ran; Jin, Wei Jun

    2013-06-28

    A novel co-crystal, [(BTEMPO)2(2+)·4I2·2I5(-)] (BTEMPO(+) = 4-benzoyloxy-2,2,6,6-tetramethylpiperidinyl-1-oxoammonium cation), was successfully constructed using iodine and 4-benzoyloxy-2,2,6,6-tetramethylpiperidinyl-1-oxy free radical (BTEMPO) as starting materials and was well characterized by XRD, Raman and calculation. The co-crystal possesses a fascinating 3D anionic cage structure formed by V-shaped-pentaiodides and iodine via multiple halogen bonding and on a template of dimeric (BTEMPO)2(2+) cations. The cationic dimers are held together by a pair of reversed C-H···O=C hydrogen bonds and stabilized the 3D cage structure by C-H···I hydrogen bonds between methyl-protons of BTEMPO(+) and iodine in the framework. The reaction mechanism of producing BTEMPO(+) and I5(-) is proposed and verified by UV-Vis spectroscopy and ESI-MS, which initially goes through a halogen bonding complex between iodine and BTEMPO free radical and then Milliken inner charge transfer and charge separation reaction. UV-Vis absorption spectroscopy confirms the halogen bonding complex between I2 and BTEMPO with a formation constant of 6.94 M(-1) and a 1 : 1 stoichiometry in chloroform. The ESI-MS directly led to observation of the less stable intermediates in the mechanism. It is believed that the mechanism proposed here is helpful in understanding the interactions between I2 and organic electron donors, which are debated frequently, and fills the gaps in the reaction mechanism of I2 with free radicals or analogues. PMID:23640048

  1. A quasi steady state method for solving transient Darcy flow in complex 3D fractured networks accounting for matrix to fracture flow

    NASA Astrophysics Data System (ADS)

    Nœtinger, B.

    2015-02-01

    Modeling natural Discrete Fracture Networks (DFN) receives more and more attention in applied geosciences, from oil and gas industry, to geothermal recovery and aquifer management. The fractures may be either natural, or artificial in case of well stimulation. Accounting for the flow inside the fracture network, and accounting for the transfers between the matrix and the fractures, with the same level of accuracy is an important issue for calibrating the well architecture and for setting up optimal resources recovery strategies. Recently, we proposed an original method allowing to model transient pressure diffusion in the fracture network only [1]. The matrix was assumed to be impervious. A systematic approximation scheme was built, allowing to model the initial DFN by a set of N unknowns located at each identified intersection between fractures. The higher N, the higher the accuracy of the model. The main assumption was using a quasi steady state hypothesis, that states that the characteristic diffusion time over one single fracture is negligible compared with the characteristic time of the macroscopic problem, e.g. change of boundary conditions. In that context, the lowest order approximation N = 1 has the form of solving a transient problem in a resistor/capacitor network, a so-called pipe network. Its topology is the same as the network of geometrical intersections between fractures. In this paper, we generalize this approach in order to account for fluxes from matrix to fractures. The quasi steady state hypothesis at the fracture level is still kept. Then, we show that in the case of well separated time scales between matrix and fractures, the preceding model needs only to be slightly modified in order to incorporate these fluxes. The additional knowledge of the so-called matrix to fracture transfer function allows to modify the mass matrix that becomes a time convolution operator. This is reminiscent of existing space averaged transient dual porosity models.

  2. Test-Bed Design and Implementation of High-Definition Multimedia Interface Based 3D Broadcast Coarse Wavelength-Division Multiplexing Access Network

    NASA Astrophysics Data System (ADS)

    Mizusawa, Jun-Ichi

    2011-10-01

    Test-bed operations of three real-time transmission types are described: a three-dimensional (+two-dimensional) high-definition multimedia interface broadcast on point-to-multi-point connections, a two-dimensional high-definition multimedia interface broadcast on multi-point-to-multi-point connections, and a three-dimensional high-definition multimedia interface full duplex on a point-to-point connection. The network design has an optical broadcast topology centered with an "optical hub." This article first introduces the design and implementation, then explains the issues and further considerations for implementing a high-definition multimedia interface based three-dimensional broadcast access network.

  3. Concentrated hydroxyapatite inks for direct-write assembly of 3-D periodic scaffolds.

    PubMed

    Michna, Sarah; Wu, Willie; Lewis, Jennifer A

    2005-10-01

    Hydroxyapatite (HA) scaffolds with a 3-D periodic architecture and multiscale porosity have been fabricated by direct-write assembly. Concentrated HA inks with tailored viscoelastic properties were developed to enable the construction of complex 3-D architectures comprised of self-supporting cylindrical rods in a layer-by-layer patterning sequence. By controlling their lattice constant and sintering conditions, 3-D periodic HA scaffolds were produced with a bimodal pore size distribution. Mercury intrusion porosimetry (MIP) was used to determine the characteristic pore size and volume associated with the interconnected pore channels between HA rods and the finer pores within the partially sintered HA rods. PMID:15878368

  4. 3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, and River Reservation, Arapaho and Shoshone Tribes, Wyoming

    SciTech Connect

    La Pointe, Paul R.; Hermanson, Jan

    2002-09-09

    The goal of this project is to improve the recovery of oil from the Circle Ridge Oilfield, located on the Wind River Reservation in Wyoming, through an innovative integration of matrix characterization, structural reconstruction, and the characterization of the fracturing in the reservoir through the use of discrete fracture network models.

  5. Probing Local Mineralogy in 3D with Dual Energy X-Ray Microscopy

    NASA Astrophysics Data System (ADS)

    Gelb, J.; Yun, S.; Doerr, D.; Hunter, L.; Johnson, B.; Merkle, A.; Fahey, K.

    2013-12-01

    In recent years, 3D imaging of rock microstructures has become routine practice for determining pore-scale properties in the geosciences. X-Ray imaging techniques, such as X-Ray Microscopy (XRM), have demonstrated several unique capabilities: namely, the ability to characterize the same sample across a range of length scales and REVs (from millimeters to nanometers), and to perform these characterizations on the same sample over a range of times/treatments (e.g., to observe fluid transporting through the pore networks in a flow cell). While the XRM technique is a popular choice for structural (i.e., pore) characterization, historically it has provided little mineralogical information. This means that resulting simulations are either based on pore structure alone, or rely on correlative chemical mapping techniques for compositionally-sensitive models. Recent advancements in XRM techniques are now enabling compositional sensitivity for a variety of geological sample types. By collecting high-resolution 3D tomography data sets at two different source settings (energies), results may be mixed together to enhance the appearance (contrast) of specific materials. This approach is proving beneficial, for example, to mining applications to locate and identify precious metals, as well as for oil & gas applications to map local hydrophobicity. Here, we will introduce the technique of dual energy X-Ray microscopy, showing how it extends the capabilities of traditional XRM techniques, affording the same high resolution structural information while adding 3D compositional data. Application examples will be shown to illustrate its effectiveness at both the single to sub-micron length scale for mining applications as well as at the 150 nm length scale for shale rock analysis.

  6. 3-D sediment-basement tomography of the Northern Marmara trough by a dense OBS network at the nodes of a grid of controlled source profiles along the North Anatolian fault

    NASA Astrophysics Data System (ADS)

    Bayrakci, G.; Laigle, M.; Bécel, A.; Hirn, A.; Taymaz, T.; Yolsal-Çevikbilen, S.; Seismarmara Team

    2013-09-01

    A 3-D tomographic inversion of first arrival times of shot profiles recorded by a dense 2-D OBS network provides an unprecedented constraint on the P-wave velocities heterogeneity of the upper-crustal part of the North Marmara Trough (NMT), over a region of 180 km long by 50 km wide. One of the specific aims of this controlled source tomography is to provide a 3-D initial model for the local earthquake tomography (LET). Hence, in an original way, the controlled source inversion has been performed by using a code dedicated to LET. After several tests to check the results trade-off with the inversion parameters, we build up a 3-D a priori velocity model, in which the sea-bottom topography, the acoustic and the crystalline basements and the Moho interfaces have been considered. The reliability of the obtained features has been checked by checkerboard tests and also by their comparison with the deep-penetration multichannel seismic profiles, and with the wide-angle reflection and refraction modelled profiles. This study provides the first 3-D view of the basement topography along the active North Anatolian fault beneath the Marmara Sea, even beneath the deepest part of three sedimentary basins of NMT. Clear basement depressions reaching down 6 km depth below the sea level (bsl) have been found beneath these basins. The North Imrali Basin located on the southern continental shelf is observed with a similar sedimentary thickness as its northern neighbours. Between Central and Çinarcik basins, the Central High rises up to 3 km depth below (bsl). Its crest position is offset by 10 km northwestward relatively to the bathymetric crest. On the contrary, Tekirdağ and Central basins appear linked, forming a 60-km-long basement depression. Beneath the bathymetric relief of Western High low velocities are observed down to 6 km depth (bsl) and no basement high have been found. The obtained 3-D Vp heterogeneity model allows the consideration of the 3-D supracrustal heterogeneity

  7. 3D model reconstruction of underground goaf

    NASA Astrophysics Data System (ADS)

    Fang, Yuanmin; Zuo, Xiaoqing; Jin, Baoxuan

    2005-10-01

    Constructing 3D model of underground goaf, we can control the process of mining better and arrange mining work reasonably. However, the shape of goaf and the laneway among goafs are very irregular, which produce great difficulties in data-acquiring and 3D model reconstruction. In this paper, we research on the method of data-acquiring and 3D model construction of underground goaf, building topological relation among goafs. The main contents are as follows: a) The paper proposed an efficient encoding rule employed to structure the field measurement data. b) A 3D model construction method of goaf is put forward, which by means of combining several TIN (triangulated irregular network) pieces, and an efficient automatic processing algorithm of boundary of TIN is proposed. c) Topological relation of goaf models is established. TIN object is the basic modeling element of goaf 3D model, and the topological relation among goaf is created and maintained by building the topological relation among TIN objects. Based on this, various 3D spatial analysis functions can be performed including transect and volume calculation of goaf. A prototype is developed, which can realized the model and algorithm proposed in this paper.

  8. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications.

    PubMed

    Wang, I-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy. PMID:27483492

  9. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    NASA Astrophysics Data System (ADS)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  10. Comment on "Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry" by M. Mahanthappa, G. Sorenson and A. Schmitt.

    PubMed

    Fischer, Michael G; Hyde, Stephen T; Schröder-Turk, Gerd E

    2015-02-14

    The article by Sorenson et al. (Soft Matter10, 8229, 2014) reports a novel phase formed by gemini surfactants in water, of symmetry P63/mcm and based on a triple intergrowth of three identical degree-three networks, known as 3etc(193). This phase is the first lyotropic liquid crystalline phase based on the intergrowth of a triplet of network- or labyrinth-like hydrophobic domains. We provide here results from self-consistent field theory that demonstrate that the same morphology is almost stable in standard AB diblock copolymer melts; at the phase transition between the double gyroid phase and the hexagonal columnar phase, the 3etc(193) morphology only incurs a marginal free energy penalty compared to the equilibrium phases. Interestingly, the ratio of lattice parameters c/a = 0.955 of the 3etc(193) as a diblock morphology is very close to that of the gemini surfactant phase and of the related IBN-9 mesoporous silicate phase (Han et al., Nat. Chem.1, 123, 2009). Based on the combination of these results, we hypothesise that the 3etc(193) morphology is likely a generic phase in soft materials, rather than an oddity. PMID:25600886

  11. Crowdsourcing Based 3d Modeling

    NASA Astrophysics Data System (ADS)

    Somogyi, A.; Barsi, A.; Molnar, B.; Lovas, T.

    2016-06-01

    Web-based photo albums that support organizing and viewing the users' images are widely used. These services provide a convenient solution for storing, editing and sharing images. In many cases, the users attach geotags to the images in order to enable using them e.g. in location based applications on social networks. Our paper discusses a procedure that collects open access images from a site frequently visited by tourists. Geotagged pictures showing the image of a sight or tourist attraction are selected and processed in photogrammetric processing software that produces the 3D model of the captured object. For the particular investigation we selected three attractions in Budapest. To assess the geometrical accuracy, we used laser scanner and DSLR as well as smart phone photography to derive reference values to enable verifying the spatial model obtained from the web-album images. The investigation shows how detailed and accurate models could be derived applying photogrammetric processing software, simply by using images of the community, without visiting the site.

  12. 3D Spectroscopy in Astronomy

    NASA Astrophysics Data System (ADS)

    Mediavilla, Evencio; Arribas, Santiago; Roth, Martin; Cepa-Nogué, Jordi; Sánchez, Francisco

    2011-09-01

    Preface; Acknowledgements; 1. Introductory review and technical approaches Martin M. Roth; 2. Observational procedures and data reduction James E. H. Turner; 3. 3D Spectroscopy instrumentation M. A. Bershady; 4. Analysis of 3D data Pierre Ferruit; 5. Science motivation for IFS and galactic studies F. Eisenhauer; 6. Extragalactic studies and future IFS science Luis Colina; 7. Tutorials: how to handle 3D spectroscopy data Sebastian F. Sánchez, Begona García-Lorenzo and Arlette Pécontal-Rousset.

  13. 3D Elevation Program—Virtual USA in 3D

    USGS Publications Warehouse

    Lukas, Vicki; Stoker, J.M.

    2016-01-01

    The U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) uses a laser system called ‘lidar’ (light detection and ranging) to create a virtual reality map of the Nation that is very accurate. 3D maps have many uses with new uses being discovered all the time.  

  14. Three-dimensional morphology of pores and cracks in intact and mechanically deformed sandstones

    NASA Astrophysics Data System (ADS)

    Menendez, B.; David, C.; Wong, T.-F.; Martinez-Nistal, A.

    2003-04-01

    We have studied four different sandstones under confocal laser scanning microscopy (CLSM). In order to discriminate the void space from the grains, the samples were impregnated with a fluorescent dyed (Rhodamine B) resin and thin-sections with a thickness larger than usual were prepared and studied with CSLM. Two different kinds of samples have been studied: mechanically deformed samples of Darley Dale and Berea sandstones and intact samples of Rothbach and Bentheim sandstones. On each sample several three dimensional blocks have been investigated with size 228 by 152 microns and depths ranging from 35 to 100 microns. From each block a series of tens of parallel "virtual sections" has been recorded, separated by 1 or 2 microns in depth. First we show some examples on Darley Dale and Berea sandstone samples deformed in triaxial experiments. Rotating animations are built from series of 3D views of reconstructed crack networks taken step by step for different block orientations. When put together these 3D views nicely simulate a rotation of the 3D block. To create and run the animations we used the Confocal Assistant free software on a PC. Spectacular 3D animations representing crack networks in mechanically deformed samples are obtained this way in a very short time: some examples will be shown on the screen. Secondly we show on a poster some static 3D reconstructions of the pore and/or crack networks obtained using the Slicer Dicer software. For the intact samples we observe that pore (or grain) walls are smoother in Bentheim sandstone whereas in Rothbach sandstone the presence of a significant amount of coating clay minerals results in a visible surface roughness. Some differences in pore size and pore shape were also observed, with a more homogeneous distribution in Bentheim sandstone than in Rothbach sandstone. In both sandstones we observe the classical pore-to-throats junctions. Complex contact geometry between adjacent grains are sometimes observed. In the

  15. Slope instability in complex 3D topography promoted by convergent 3D groundwater flow

    NASA Astrophysics Data System (ADS)

    Reid, M. E.; Brien, D. L.

    2012-12-01

    Slope instability in complex topography is generally controlled by the interaction between gravitationally induced stresses, 3D strengths, and 3D pore-fluid pressure fields produced by flowing groundwater. As an example of this complexity, coastal bluffs sculpted by landsliding commonly exhibit a progression of undulating headlands and re-entrants. In this landscape, stresses differ between headlands and re-entrants and 3D groundwater flow varies from vertical rainfall infiltration to lateral groundwater flow on lower permeability layers with subsequent discharge at the curved bluff faces. In plan view, groundwater flow converges in the re-entrant regions. To investigate relative slope instability induced by undulating topography, we couple the USGS 3D limit-equilibrium slope-stability model, SCOOPS, with the USGS 3D groundwater flow model, MODFLOW. By rapidly analyzing the stability of millions of potential failures, the SCOOPS model can determine relative slope stability throughout the 3D domain underlying a digital elevation model (DEM), and it can utilize both fully 3D distributions of pore-water pressure and material strength. The two models are linked by first computing a groundwater-flow field in MODFLOW, and then computing stability in SCOOPS using the pore-pressure field derived from groundwater flow. Using these two models, our analyses of 60m high coastal bluffs in Seattle, Washington showed augmented instability in topographic re-entrants given recharge from a rainy season. Here, increased recharge led to elevated perched water tables with enhanced effects in the re-entrants owing to convergence of groundwater flow. Stability in these areas was reduced about 80% compared to equivalent dry conditions. To further isolate these effects, we examined groundwater flow and stability in hypothetical landscapes composed of uniform and equally spaced, oscillating headlands and re-entrants with differing amplitudes. The landscapes had a constant slope for both

  16. Reconstructing input for artificial neural networks based on embedding theory and mutual information to simulate soil pore water salinity in tidal floodplain

    NASA Astrophysics Data System (ADS)

    Zheng, Fawen; Wan, Yongshan; Song, Keunyea; Sun, Detong; Hedgepeth, Marion

    2016-01-01

    Soil pore water salinity plays an important role in the distribution of vegetation and biogeochemical processes in coastal floodplain ecosystems. In this study, artificial neural networks (ANNs) were applied to simulate the pore water salinity of a tidal floodplain in Florida. We present an approach based on embedding theory with mutual information to reconstruct ANN model input time series from one system state variable. Mutual information between system output and input was computed and the local minimum mutual information points were used to determine a time lag vector for time series embedding and reconstruction, with which the mutual information weighted average method was developed to compute the components of reconstructed time series. The optimal embedding dimension was obtained by optimizing model performance. The method was applied to simulate soil pore water salinity dynamics at 12 probe locations in the tidal floodplain influenced by saltwater intrusion using 4 years (2005-2008) data, in which adjacent river water salinity was used to reconstruct model input. The simulated electrical conductivity of the pore water showed close agreement with field observations (RMSE and ), suggesting the reconstructed input by the proposed approach provided adequate input information for ANN modeling. Multiple linear regression model, partial mutual information algorithm for input variable selection, k-NN algorithm, and simple time delay embedding were also used to further verify the merit of the proposed approach.

  17. Global optimization of data quality checks on 2-D and 3-D networks of GPR cross-well tomographic data for automatic correction of unknown well deviations

    SciTech Connect

    Sassen, D. S.; Peterson, J. E.

    2010-03-15

    Significant errors related to poor time zero estimation, well deviation or mislocation of the transmitter (TX) and receiver (RX) stations can render even the most sophisticated modeling and inversion routine useless. Previous examples of methods for the analysis and correction of data errors in geophysical tomography include the works of Maurer and Green (1997), Squires et al. (1992) and Peterson (2001). Here we follow the analysis and techniques of Peterson (2001) for data quality control and error correction. Through our data acquisition and quality control procedures we have very accurate control on the surface locations of wells, the travel distance of both the transmitter and receiver within the boreholes, and the change in apparent zero time. However, we often have poor control on well deviations, either because of economic constraints or the nature of the borehole itself prevented the acquisition of well deviation logs. Also, well deviation logs can sometimes have significant errors. Problems with borehole deviations can be diagnosed prior to inversion of travel-time tomography data sets by plotting the apparent velocity of a straight ray connecting a transmitter (TX) to a receiver (RX) against the take-off angle of the ray. Issues with the time-zero pick or distances between wells appear as symmetric smiles or frown in these QC plots. Well deviation or dipping-strong anisotropy will result in an asymmetric correlation between apparent velocity and take-off angle (Figure 1-B). In addition, when a network of interconnected GPR tomography data is available, one has the additional quality constraint of insuring that there is continuity in velocity between immediately adjacent tomograms. A sudden shift in the mean velocity indicates that either position deviations are present or there is a shift in the pick times. Small errors in well geometry may be effectively treated during inversion by including weighting, or relaxation, parameters into the inversion (e

  18. Modular 3-D Transport model

    EPA Science Inventory

    MT3D was first developed by Chunmiao Zheng in 1990 at S.S. Papadopulos & Associates, Inc. with partial support from the U.S. Environmental Protection Agency (USEPA). Starting in 1990, MT3D was released as a pubic domain code from the USEPA. Commercial versions with enhanced capab...

  19. Market study: 3-D eyetracker

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A market study of a proposed version of a 3-D eyetracker for initial use at NASA's Ames Research Center was made. The commercialization potential of a simplified, less expensive 3-D eyetracker was ascertained. Primary focus on present and potential users of eyetrackers, as well as present and potential manufacturers has provided an effective means of analyzing the prospects for commercialization.

  20. LLNL-Earth3D

    2013-10-01

    Earth3D is a computer code designed to allow fast calculation of seismic rays and travel times through a 3D model of the Earth. LLNL is using this for earthquake location and global tomography efforts and such codes are of great interest to the Earth Science community.

  1. [3-D ultrasound in gastroenterology].

    PubMed

    Zoller, W G; Liess, H

    1994-06-01

    Three-dimensional (3D) sonography represents a development of noninvasive diagnostic imaging by real-time two-dimensional (2D) sonography. The use of transparent rotating scans, comparable to a block of glass, generates a 3D effect. The objective of the present study was to optimate 3D presentation of abdominal findings. Additional investigations were made with a new volumetric program to determine the volume of selected findings of the liver. The results were compared with the estimated volumes of 2D sonography and 2D computer tomography (CT). For the processing of 3D images, typical parameter constellations were found for the different findings, which facilitated processing of 3D images. In more than 75% of the cases examined we found an optimal 3D presentation of sonographic findings with respect to the evaluation criteria developed by us for the 3D imaging of processed data. Great differences were found for the estimated volumes of the findings of the liver concerning the three different techniques applied. 3D ultrasound represents a valuable method to judge morphological appearance in abdominal findings. The possibility of volumetric measurements enlarges its potential diagnostic significance. Further clinical investigations are necessary to find out if definite differentiation between benign and malign findings is possible. PMID:7919882

  2. 3D World Building System

    SciTech Connect

    2013-10-30

    This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

  3. 3D World Building System

    ScienceCinema

    None

    2014-02-26

    This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

  4. PLOT3D user's manual

    NASA Technical Reports Server (NTRS)

    Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.

    1990-01-01

    PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.

  5. 3D printing in dentistry.

    PubMed

    Dawood, A; Marti Marti, B; Sauret-Jackson, V; Darwood, A

    2015-12-01

    3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery. PMID:26657435

  6. 3-D Shear Wave Velocity Model of Mexico and South US: Bridging Seismic Networks with Ambient Noise Cross-Correlations (C1) and Correlation of Coda of Correlations (C3).

    NASA Astrophysics Data System (ADS)

    Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba Montiel, Francisco; Iglesias, Arturo

    2016-07-01

    This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group travel times are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.

  7. 3-D shear wave velocity model of Mexico and South US: bridging seismic networks with ambient noise cross-correlations (C1) and correlation of coda of correlations (C3)

    NASA Astrophysics Data System (ADS)

    Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba-Montiel, Francisco; Iglesias, Arturo

    2016-09-01

    This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group traveltimes are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.

  8. Three-Dimensional Scaffolds for Tissue Engineering Applications: Role of Porosity and Pore Size

    PubMed Central

    Loh, Qiu Li

    2013-01-01

    Tissue engineering applications commonly encompass the use of three-dimensional (3D) scaffolds to provide a suitable microenvironment for the incorporation of cells or growth factors to regenerate damaged tissues or organs. These scaffolds serve to mimic the actual in vivo microenvironment where cells interact and behave according to the mechanical cues obtained from the surrounding 3D environment. Hence, the material properties of the scaffolds are vital in determining cellular response and fate. These 3D scaffolds are generally highly porous with interconnected pore networks to facilitate nutrient and oxygen diffusion and waste removal. This review focuses on the various fabrication techniques (e.g., conventional and rapid prototyping methods) that have been employed to fabricate 3D scaffolds of different pore sizes and porosity. The different pore size and porosity measurement methods will also be discussed. Scaffolds with graded porosity have also been studied for their ability to better represent the actual in vivo situation where cells are exposed to layers of different tissues with varying properties. In addition, the ability of pore size and porosity of scaffolds to direct cellular responses and alter the mechanical properties of scaffolds will be reviewed, followed by a look at nature's own scaffold, the extracellular matrix. Overall, the limitations of current scaffold fabrication approaches for tissue engineering applications and some novel and promising alternatives will be highlighted. PMID:23672709

  9. PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into

  10. PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into

  11. Culturing Cells in 3D Ordered Cellular Solids

    NASA Astrophysics Data System (ADS)

    Lin, Keng-Hui; Lin, Wang-Jung; Lin, Jing-Ying

    2011-03-01

    Constructing a well-defined 3D microenvironment for cell growth is a key step for tissue engineering and mechanobiology. We demonstrate high-throughput fabrication of gelatin-based ordered cellular solids with tunable pore size and solid fraction. This process involves generating monodisperse liquid foam with a cross-flow microfluidic device. The monodisperse liquid foam was further processed into open-cell solid foam, which was used as scaffolds for 3D cell culture. Three distinct cell types were cultured under these conditions and displayed appropriate physiological, morphological, and functional characteristics. Epithelial cells formed cyst-like structures and were polarized inside pores, myoblasts adopted a tubular structure and fused into myotubes, and fibroblasts exhibited wide varieties of morphologies depending on their location inside the scaffolds. These ordered cellular solids therefore make possible the study of pore-size effects on cells.

  12. Temperature dependent structural variation from 2D supramolecular network to 3D interpenetrated metal–organic framework: In situ cleavage of S–S and C–S bonds

    SciTech Connect

    Ugale, Bharat; Singh, Divyendu; Nagaraja, C.M.

    2015-03-15

    Two new Zn(II)–organic compounds, [Zn(muco)(dbds){sub 2}(H{sub 2}O){sub 2}] (1) and [Zn(muco)(dbs)] (2) (where, muco=trans, trans-muconate dianion, dbds=4,4′-dipyridyldisulfide and dbs=4,4′-dipyridylsulfide) have been synthesized from same precursors but at two different temperatures. Both the compounds have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectroscopy, thermal analysis and photoluminescence studies. Compound 1 prepared at room temperature possesses a molecular structure extended to 2D supramolecular network through (H–O…H) hydrogen-bonding interactions. Compound 2, obtained at high temperature (100 °C) shows a 3-fold interpenetrating 3D framework constituted by an in situ generated dbs linker by the cleavage of S–S and C–S bonds of dbds linker. Thus, the influence of reaction temperature on the formation of two structural phases has been demonstrated. Both 1 and 2 exhibit ligand based luminescence emission owing to n→π⁎ and π→π⁎ transitions and also high thermal stabilities. - Graphical abstract: The influence of temperature on the formation of two structural phases, a 2D supramolecular network and a 3D 3-fold interpenetrating framework has been demonstrated and their luminescence emission is measured. - Highlights: • Two new Zn(II)–organic compounds were synthesized by tuning reaction temperatures. • Temperature induced in situ generation of dbs linker has been observed. • The compounds exhibit high thermal stability and luminescence emission properties. • The effect of temperature on structure, dimension and topology has been presented.

  13. Surface water, groundwater and unified 3D-crack network as a triple coupling dynamic system for a river watershed functioning - manifestation in catastrophic floods

    NASA Astrophysics Data System (ADS)

    Trifonova, Tatiana; Tulenev, Nikita; Trifonov, Dmitriy; Arakelian, Sergei

    2014-05-01

    1. Surface water and groundwater interaction model under conditions of huge level of precipitation in catastrophic floods and mudflows for mountain river watershed is introduced. Seismic processes and volcanic activity impact on the formation of disastrous floods due to dramatic change of the pressure field in groundwater horizons, is under discussion for such a triple coupling system, i.e. surface water - groundwater - crack network. Under the conception we analyze recent (2013) catastrophic water events: the catastrophic floods in Western Europe (May-June, 2013), in the Amur river basin, Russia/China (Aug.-Sept, 2013) and in Colorado, USA (Sept. 12-15,2013). In addition, a separate analysis is carried out for debris event in the Krimsk-city, Caucasus (Krasnodar) region, Russia (July 06-07, 2012). 2. There is a group of problems determined by dramatic discrepancies in water mass balance and other vital parameters, on the one hand, by estimation for different types of atmospheric precipitation (both torrential rain and continuous precipitations) and, on the other hand, for observable natural water events (i.e. catastrophic floods and/or mudflows/debris) on concrete territory. Analysis of many facts result in conclusion that we have the hard comparable/coincidence parameters under traditional conception for discussed events as an isolated/closed (river + rain) runoff-system. In contrast, the reasonable point of view does exist if we take into account the contribution of extra water source, which should be localized in river channel, i.e. functioning of open [(river + rain) + groundwater] flow-system has a principal meaning to understand the events occurrence. 3. The analysis and modeling for the events are carried out by us taking into account the following databases: (i) groundwater map dislocation, it resources and flow balance in studied areas, especially near the land surface being unstable in hydrological sense by many reasons, as well due to heavy rain

  14. Three-dimensional mixed-wet random pore-scale network modeling of two- and three-phase flow in porous media. II. Results

    NASA Astrophysics Data System (ADS)

    Piri, Mohammad; Blunt, Martin J.

    2005-02-01

    We use the model described in Piri and Blunt [Phys. Rev. E 71, 026301 (2005)] to predict two- and three-phase relative permeabilities of Berea sandstone using a random network to represent the pore space. We predict measured relative permeabilities for two-phase flow in a water-wet system. We then successfully predict the steady-state oil, water, and gas three-phase relative permeabilities measured by Oak (Proceedings of the SPE/DOE Seventh Symposium on Enhanced Oil Recovery, Tulsa, OK, 1990). We also study secondary and tertiary gas injection into media of different wettability and initial oil saturation and interpret the results in terms of pore-scale displacement processes.

  15. Three-dimensional mixed-wet random pore-scale network modeling of two- and three-phase flow in porous media. II. Results.

    PubMed

    Piri, Mohammad; Blunt, Martin J

    2005-02-01

    We use the model described in Piri and Blunt [Phys. Rev. E 71, 026301 (2005)] to predict two- and three-phase relative permeabilities of Berea sandstone using a random network to represent the pore space. We predict measured relative permeabilities for two-phase flow in a water-wet system. We then successfully predict the steady-state oil, water, and gas three-phase relative permeabilities measured by Oak (Proceedings of the SPE/DOE Seventh Symposium on Enhanced Oil Recovery, Tulsa, OK, 1990). We also study secondary and tertiary gas injection into media of different wettability and initial oil saturation and interpret the results in terms of pore-scale displacement processes. PMID:15783414

  16. Recent Advances in Characterizing Depositional Facies and Pore Network Modeling in Context of Carbon Capture Storage: An Example from the Cambrian Mt. Simon Sandstone in the Illinois Basin

    NASA Astrophysics Data System (ADS)

    Freiburg, J. T.; Nathan, W.; Best, J.; Reesink, A.; Ritzi, R. W., Jr.; Pendleton, J.; Dominic, D. F.; Tudek, J.; Kohanpur, A. H.

    2015-12-01

    In order to understand subsurface flow dynamics, including CO2 plume migration and capillary trapping, a diverse set of geologic properties within the reservoir, from the pore scale to the basin scale, must be understood and quantified. The uncertainty about site-specific geology stems from the inherent variation in rock types, depositional environments, and diagenesis. In collaboration with geocellular and multiphase modeling, detailed characterization of the Lower Mt. Simon Sandstone (LMSS), a reservoir utilized for carbon capture storage, is supporting data-driven conceptual models to better understand reservoir heterogeneity and its relationship to reservoir properties. This includes characterization of sedimentary facies and pore scale modeling of the reservoir The Cambrian-age Lower Mt. Simon Sandstone (LMSS) is a reservoir utilized for two-different carbon capture storage projects in the Illinois Basin, USA. The LMSS is interpreted to have formed in a braided river environment comprising a hierarchy of stratification, with larger scale depositional facies comprising assemblages of smaller scale facies. The proportions, geometries, length scales, and petrophysical attributes of the depositional facies, and of the textural facies they comprise, are being quantified. Based on examination of core and analog outcrop in adjacent areas, the LMSS is comprised of five dominant depositional facies, the most abundant facies being planar to trough cross-bedded sandstones produced by subaqueous sand dunes. This facies has the best reservoir conditions with porosity up to 27% and permeability up to 470 mD. Three-dimensional pore network modeling via micro computed tomography of this facies shows well-connected and unobstructed pore throats and pore space. This presentation will outline the depositional heterogeneity of the LMSS, its relationship to diagenetic fabrics, and its influence on fluid movement within the reservoir.

  17. Characterization of geologic media using Minkowski functionals and applying pore connectivity as an extra ruling factor when estimating permeability

    NASA Astrophysics Data System (ADS)

    Rodrigues, L. M.; Anwar, S.

    2013-12-01

    Over the last two decades, several approaches to characterize porous medium were developed. One of them being the topology based Minkowski functionals, which are basic geometric measures defined for binary image of porous media. By segmenting three-dimensional (3D) pore space representations, it is possible to characterize quantitatively structural features at the pore scale such as porosity, pore mean curvature, specific surficial area, and pore connectivity using these measures. Structural features are believed to strongly control the permeability of porous media; however a rigorous mathematical validation of such relationship between structural features and the hydraulic property is missing in the literature. We hypothesize that rock permeability not only depend on the macroscopic properties such as porosity and grain size distribution but also depend on the structural features of porous media such as pore connectivity, specific surficial area, and pore mean curvature. We aim to develop a relationship between such structural features of porous media that occurs at pore scale with macroscopic properties such as hydraulic conductivity. Our hypothesis is tested by using a numerical scheme for computational fluid dynamics called Lattice Boltzmann method (LBM), which enables the estimation of hydraulic parameters such as tortuosity and permeability which are relatively difficult and time consuming when obtained from laboratory experiments. 3D pore networks with similar porosity but significantly different structural properties are numerically generated using SGeMS. A series of LBM based flow simulations in different 3D pore networks are designed to understand the correlation between the structural property of porous media and its permeability.

  18. Bioprinting of 3D hydrogels.

    PubMed

    Stanton, M M; Samitier, J; Sánchez, S

    2015-08-01

    Three-dimensional (3D) bioprinting has recently emerged as an extension of 3D material printing, by using biocompatible or cellular components to build structures in an additive, layer-by-layer methodology for encapsulation and culture of cells. These 3D systems allow for cell culture in a suspension for formation of highly organized tissue or controlled spatial orientation of cell environments. The in vitro 3D cellular environments simulate the complexity of an in vivo environment and natural extracellular matrices (ECM). This paper will focus on bioprinting utilizing hydrogels as 3D scaffolds. Hydrogels are advantageous for cell culture as they are highly permeable to cell culture media, nutrients, and waste products generated during metabolic cell processes. They have the ability to be fabricated in customized shapes with various material properties with dimensions at the micron scale. 3D hydrogels are a reliable method for biocompatible 3D printing and have applications in tissue engineering, drug screening, and organ on a chip models. PMID:26066320

  19. Unassisted 3D camera calibration

    NASA Astrophysics Data System (ADS)

    Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.

    2012-03-01

    With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.

  20. Fdf in US3D

    NASA Astrophysics Data System (ADS)

    Otis, Collin; Ferrero, Pietro; Candler, Graham; Givi, Peyman

    2013-11-01

    The scalar filtered mass density function (SFMDF) methodology is implemented into the computer code US3D. This is an unstructured Eulerian finite volume hydrodynamic solver and has proven very effective for simulation of compressible turbulent flows. The resulting SFMDF-US3D code is employed for large eddy simulation (LES) on unstructured meshes. Simulations are conducted of subsonic and supersonic flows under non-reacting and reacting conditions. The consistency and the accuracy of the simulated results are assessed along with appraisal of the overall performance of the methodology. The SFMDF-US3D is now capable of simulating high speed flows in complex configurations.

  1. Wavefront construction in 3-D

    SciTech Connect

    Chilcoat, S.R. Hildebrand, S.T.

    1995-12-31

    Travel time computation in inhomogeneous media is essential for pre-stack Kirchhoff imaging in areas such as the sub-salt province in the Gulf of Mexico. The 2D algorithm published by Vinje, et al, has been extended to 3D to compute wavefronts in complicated inhomogeneous media. The 3D wavefront construction algorithm provides many advantages over conventional ray tracing and other methods of computing travel times in 3D. The algorithm dynamically maintains a reasonably consistent ray density without making a priori guesses at the number of rays to shoot. The determination of caustics in 3D is a straight forward geometric procedure. The wavefront algorithm also enables the computation of multi-valued travel time surfaces.

  2. Heterodyne 3D ghost imaging

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Zhang, Yong; Yang, Chenghua; Xu, Lu; Wang, Qiang; Zhao, Yuan

    2016-06-01

    Conventional three dimensional (3D) ghost imaging measures range of target based on pulse fight time measurement method. Due to the limit of data acquisition system sampling rate, range resolution of the conventional 3D ghost imaging is usually low. In order to take off the effect of sampling rate to range resolution of 3D ghost imaging, a heterodyne 3D ghost imaging (HGI) system is presented in this study. The source of HGI is a continuous wave laser instead of pulse laser. Temporal correlation and spatial correlation of light are both utilized to obtain the range image of target. Through theory analysis and numerical simulations, it is demonstrated that HGI can obtain high range resolution image with low sampling rate.

  3. Combinatorial 3D Mechanical Metamaterials

    NASA Astrophysics Data System (ADS)

    Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin

    2015-03-01

    We present a class of elastic structures which exhibit 3D-folding motion. Our structures consist of cubic lattices of anisotropic unit cells that can be tiled in a complex combinatorial fashion. We design and 3d-print this complex ordered mechanism, in which we combine elastic hinges and defects to tailor the mechanics of the material. Finally, we use this large design space to encode smart functionalities such as surface patterning and multistability.

  4. From 3D view to 3D print

    NASA Astrophysics Data System (ADS)

    Dima, M.; Farisato, G.; Bergomi, M.; Viotto, V.; Magrin, D.; Greggio, D.; Farinato, J.; Marafatto, L.; Ragazzoni, R.; Piazza, D.

    2014-08-01

    In the last few years 3D printing is getting more and more popular and used in many fields going from manufacturing to industrial design, architecture, medical support and aerospace. 3D printing is an evolution of bi-dimensional printing, which allows to obtain a solid object from a 3D model, realized with a 3D modelling software. The final product is obtained using an additive process, in which successive layers of material are laid down one over the other. A 3D printer allows to realize, in a simple way, very complex shapes, which would be quite difficult to be produced with dedicated conventional facilities. Thanks to the fact that the 3D printing is obtained superposing one layer to the others, it doesn't need any particular work flow and it is sufficient to simply draw the model and send it to print. Many different kinds of 3D printers exist based on the technology and material used for layer deposition. A common material used by the toner is ABS plastics, which is a light and rigid thermoplastic polymer, whose peculiar mechanical properties make it diffusely used in several fields, like pipes production and cars interiors manufacturing. I used this technology to create a 1:1 scale model of the telescope which is the hardware core of the space small mission CHEOPS (CHaracterising ExOPlanets Satellite) by ESA, which aims to characterize EXOplanets via transits observations. The telescope has a Ritchey-Chrétien configuration with a 30cm aperture and the launch is foreseen in 2017. In this paper, I present the different phases for the realization of such a model, focusing onto pros and cons of this kind of technology. For example, because of the finite printable volume (10×10×12 inches in the x, y and z directions respectively), it has been necessary to split the largest parts of the instrument in smaller components to be then reassembled and post-processed. A further issue is the resolution of the printed material, which is expressed in terms of layers

  5. Using outcrop observations, 3D discrete feature network (DFN) fluid-flow simulations, and subsurface data to constrain the impact of normal faults and opening mode fractures on fluid flow in an active asphalt mine

    NASA Astrophysics Data System (ADS)

    Wilson, C. E.; Aydin, A.; Durlofsky, L.; Karimi-Fard, M.; Brownlow, D. T.

    2008-12-01

    An active quarry near Uvalde, TX which mines asphaltic limestone from the Anacacho Formation offers an ideal setting to study fluid-flow in fractured and faulted carbonate rocks. Semi-3D exposures of normal faults and fractures in addition to visual evidence of asphalt concentrations in the quarry help constrain relationships between geologic structures and the flow and transport of hydrocarbons. Furthermore, a subsurface dataset which includes thin sections and measured asphalt concentration from the surrounding region provides a basis to estimate asphalt concentrations and constrain the depositional architecture of both the previously mined portions of the quarry and the un-mined surrounding rock volume. We characterized a series of normal faults and opening mode fractures at the quarry and documented a correlation between the intensity and distribution of these structures with increased concentrations of asphalt. The three-dimensional depositional architecture of the Anacacho Formation was characterized using the subsurface thin sections. Then outcrop exposures of faults, fractured beds, and stratigraphic contacts were mapped and their three-dimensional positions were recorded with differential gps devices. These two datasets were assimilated and a quarry-scale, geologically realistic, three-dimensional Discrete Feature Network (DFN) which represents the geometries and material properties of the matrix, normal faults, and fractures within the quarry was constructed. We then performed two-point flux, control-volume finite- difference fluid-flow simulations with the DFN to investigate the 3D flow and transport of fluids. The results were compared and contrasted with available asphalt concentration estimates from the mine and the aforementioned data from the surrounding drill cores.

  6. Pore-Scale X-ray Micro-CT Imaging and Analysis of Oil Shales

    NASA Astrophysics Data System (ADS)

    Saif, T.

    2015-12-01

    The pore structure and the connectivity of the pore space during the pyrolysis of oil shales are important characteristics which determine hydrocarbon flow behaviour and ultimate recovery. We study the effect of temperature on the evolution of pore space and subsequent permeability on five oil shale samples: (1) Vernal Utah United States, (2) El Lajjun Al Karak Jordan, (3) Gladstone Queensland Australia (4) Fushun China and (5) Kimmerdige United Kingdom. Oil Shale cores of 5mm in diameter were pyrolized at 300, 400 and 500 °C. 3D imaging of 5mm diameter core samples was performed at 1μm voxel resolution using X-ray micro computed tomography (CT) and the evolution of the pore structures were characterized. The experimental results indicate that the thermal decomposition of kerogen at high temperatures is a major factor causing micro-scale changes in the internal structure of oil shales. At the early stage of pyrolysis, micron-scale heterogeneous pores were formed and with a further increase in temperature, the pores expanded and became interconnected by fractures. Permeability for each oil shale sample at each temperature was computed by simulation directly on the image voxels and by pore network extraction and simulation. Future work will investigate different samples and pursue insitu micro-CT imaging of oil shale pyrolysis to characterize the time evolution of the pore space.

  7. YouDash3D: exploring stereoscopic 3D gaming for 3D movie theaters

    NASA Astrophysics Data System (ADS)

    Schild, Jonas; Seele, Sven; Masuch, Maic

    2012-03-01

    Along with the success of the digitally revived stereoscopic cinema, events beyond 3D movies become attractive for movie theater operators, i.e. interactive 3D games. In this paper, we present a case that explores possible challenges and solutions for interactive 3D games to be played by a movie theater audience. We analyze the setting and showcase current issues related to lighting and interaction. Our second focus is to provide gameplay mechanics that make special use of stereoscopy, especially depth-based game design. Based on these results, we present YouDash3D, a game prototype that explores public stereoscopic gameplay in a reduced kiosk setup. It features live 3D HD video stream of a professional stereo camera rig rendered in a real-time game scene. We use the effect to place the stereoscopic effigies of players into the digital game. The game showcases how stereoscopic vision can provide for a novel depth-based game mechanic. Projected trigger zones and distributed clusters of the audience video allow for easy adaptation to larger audiences and 3D movie theater gaming.

  8. Speaking Volumes About 3-D

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In 1999, Genex submitted a proposal to Stennis Space Center for a volumetric 3-D display technique that would provide multiple users with a 360-degree perspective to simultaneously view and analyze 3-D data. The futuristic capabilities of the VolumeViewer(R) have offered tremendous benefits to commercial users in the fields of medicine and surgery, air traffic control, pilot training and education, computer-aided design/computer-aided manufacturing, and military/battlefield management. The technology has also helped NASA to better analyze and assess the various data collected by its satellite and spacecraft sensors. Genex capitalized on its success with Stennis by introducing two separate products to the commercial market that incorporate key elements of the 3-D display technology designed under an SBIR contract. The company Rainbow 3D(R) imaging camera is a novel, three-dimensional surface profile measurement system that can obtain a full-frame 3-D image in less than 1 second. The third product is the 360-degree OmniEye(R) video system. Ideal for intrusion detection, surveillance, and situation management, this unique camera system offers a continuous, panoramic view of a scene in real time.

  9. Java 3D Interactive Visualization for Astrophysics

    NASA Astrophysics Data System (ADS)

    Chae, K.; Edirisinghe, D.; Lingerfelt, E. J.; Guidry, M. W.

    2003-05-01

    We are developing a series of interactive 3D visualization tools that employ the Java 3D API. We have applied this approach initially to a simple 3-dimensional galaxy collision model (restricted 3-body approximation), with quite satisfactory results. Running either as an applet under Web browser control, or as a Java standalone application, this program permits real-time zooming, panning, and 3-dimensional rotation of the galaxy collision simulation under user mouse and keyboard control. We shall also discuss applications of this technology to 3-dimensional visualization for other problems of astrophysical interest such as neutron star mergers and the time evolution of element/energy production networks in X-ray bursts. *Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.

  10. 3D-Printed Microfluidics.

    PubMed

    Au, Anthony K; Huynh, Wilson; Horowitz, Lisa F; Folch, Albert

    2016-03-14

    The advent of soft lithography allowed for an unprecedented expansion in the field of microfluidics. However, the vast majority of PDMS microfluidic devices are still made with extensive manual labor, are tethered to bulky control systems, and have cumbersome user interfaces, which all render commercialization difficult. On the other hand, 3D printing has begun to embrace the range of sizes and materials that appeal to the developers of microfluidic devices. Prior to fabrication, a design is digitally built as a detailed 3D CAD file. The design can be assembled in modules by remotely collaborating teams, and its mechanical and fluidic behavior can be simulated using finite-element modeling. As structures are created by adding materials without the need for etching or dissolution, processing is environmentally friendly and economically efficient. We predict that in the next few years, 3D printing will replace most PDMS and plastic molding techniques in academia. PMID:26854878

  11. Computational study of 3-D hot-spot initiation in shocked insensitive high-explosive

    NASA Astrophysics Data System (ADS)

    Najjar, F. M.; Howard, W. M.; Fried, L. E.; Manaa, M. R.; Nichols, A., III; Levesque, G.

    2012-03-01

    High-explosive (HE) material consists of large-sized grains with micron-sized embedded impurities and pores. Under various mechanical/thermal insults, these pores collapse generating hightemperature regions leading to ignition. A hydrodynamic study has been performed to investigate the mechanisms of pore collapse and hot spot initiation in TATB crystals, employing a multiphysics code, ALE3D, coupled to the chemistry module, Cheetah. This computational study includes reactive dynamics. Two-dimensional high-resolution large-scale meso-scale simulations have been performed. The parameter space is systematically studied by considering various shock strengths, pore diameters and multiple pore configurations. Preliminary