3-D Mesh Generation Nonlinear Systems
Christon, M. A.; Dovey, D.; Stillman, D. W.; Hallquist, J. O.; Rainsberger, R. B
1994-04-07
INGRID is a general-purpose, three-dimensional mesh generator developed for use with finite element, nonlinear, structural dynamics codes. INGRID generates the large and complex input data files for DYNA3D, NIKE3D, FACET, and TOPAZ3D. One of the greatest advantages of INGRID is that virtually any shape can be described without resorting to wedge elements, tetrahedrons, triangular elements or highly distorted quadrilateral or hexahedral elements. Other capabilities available are in the areas of geometry and graphics. Exact surface equations and surface intersections considerably improve the ability to deal with accurate models, and a hidden line graphics algorithm is included which is efficient on the most complicated meshes. The primary new capability is associated with the boundary conditions, loads, and material properties required by nonlinear mechanics programs. Commands have been designed for each case to minimize user effort. This is particularly important since special processing is almost always required for each load or boundary condition.
Shape design sensitivities using fully automatic 3-D mesh generation
NASA Technical Reports Server (NTRS)
Botkin, M. E.
1990-01-01
Previous work in three dimensional shape optimization involved specifying design variables by associating parameters directly with mesh points. More recent work has shown the use of fully-automatic mesh generation based upon a parameterized geometric representation. Design variables have been associated with a mathematical model of the part rather than the discretized representation. The mesh generation procedure uses a nonuniform grid intersection technique to place nodal points directly on the surface geometry. Although there exists an associativity between the mesh and the geometrical/topological entities, there is no mathematical functional relationship. This poses a problem during certain steps in the optimization process in which geometry modification is required. For the large geometrical changes which occur at the beginning of each optimization step, a completely new mesh is created. However, for gradient calculations many small changes must be made and it would be too costly to regenerate the mesh for each design variable perturbation. For that reason, a local remeshing procedure has been implemented which operates only on the specific edges and faces associated with the design variable being perturbed. Two realistic design problems are presented which show the efficiency of this process and test the accuracy of the gradient computations.
Hex-dominant mesh generation using 3D constrained triangulation
OWEN,STEVEN J.
2000-05-30
A method for decomposing a volume with a prescribed quadrilateral surface mesh, into a hexahedral-dominated mesh is proposed. With this method, known as Hex-Morphing (H-Morph), an initial tetrahedral mesh is provided. Tetrahedral are transformed and combined starting from the boundary and working towards the interior of the volume. The quadrilateral faces of the hexahedra are treated as internal surfaces, which can be recovered using constrained triangulation techniques. Implementation details of the edge and face recovery process are included. Examples and performance of the H-Morph algorithm are also presented.
Isoparametric 3-D Finite Element Mesh Generation Using Interactive Computer Graphics
NASA Technical Reports Server (NTRS)
Kayrak, C.; Ozsoy, T.
1985-01-01
An isoparametric 3-D finite element mesh generator was developed with direct interface to an interactive geometric modeler program called POLYGON. POLYGON defines the model geometry in terms of boundaries and mesh regions for the mesh generator. The mesh generator controls the mesh flow through the 2-dimensional spans of regions by using the topological data and defines the connectivity between regions. The program is menu driven and the user has a control of element density and biasing through the spans and can also apply boundary conditions, loads interactively.
Lee, W; Kim, T-S; Cho, M; Lee, S
2005-01-01
In studying bioelectromagnetic problems, finite element method offers several advantages over other conventional methods such as boundary element method. It allows truly volumetric analysis and incorporation of material properties such as anisotropy. Mesh generation is the first requirement in the finite element analysis and there are many different approaches in mesh generation. However conventional approaches offered by commercial packages and various algorithms do not generate content-adaptive meshes, resulting in numerous elements in the smaller volume regions, thereby increasing computational load and demand. In this work, we present an improved content-adaptive mesh generation scheme that is efficient and fast along with options to change the contents of meshes. For demonstration, mesh models of the head from a volume MRI are presented in 2-D and 3-D.
Spear, A. D.; Hochhalter, J. D.; Cerrone, A. R.; ...
2016-04-27
In an effort to reproduce computationally the observed evolution of microstructurally small fatigue cracks (MSFCs), a method is presented for generating conformal, finite-element (FE), volume meshes from 3D measurements of MSFC propagation. The resulting volume meshes contain traction-free surfaces that conform to incrementally measured 3D crack shapes. Grain morphologies measured using near-field high-energy X-ray diffraction microscopy are also represented within the FE volume meshes. Proof-of-concept simulations are performed to demonstrate the utility of the mesh-generation method. The proof-of-concept simulations employ a crystal-plasticity constitutive model and are performed using the conformal FE meshes corresponding to successive crack-growth increments. Although the simulationsmore » for each crack increment are currently independent of one another, they need not be, and transfer of material-state information among successive crack-increment meshes is discussed. The mesh-generation method was developed using post-mortem measurements, yet it is general enough that it can be applied to in-situ measurements of 3D MSFC propagation.« less
A tetrahedral mesh generation approach for 3D marine controlled-source electromagnetic modeling
NASA Astrophysics Data System (ADS)
Um, Evan Schankee; Kim, Seung-Sep; Fu, Haohuan
2017-03-01
3D finite-element (FE) mesh generation is a major hurdle for marine controlled-source electromagnetic (CSEM) modeling. In this paper, we present a FE discretization operator (FEDO) that automatically converts a 3D finite-difference (FD) model into reliable and efficient tetrahedral FE meshes for CSEM modeling. FEDO sets up wireframes of a background seabed model that precisely honors the seafloor topography. The wireframes are then partitioned into multiple regions. Outer regions of the wireframes are discretized with coarse tetrahedral elements whose maximum size is as large as a skin depth of the regions. We demonstrate that such coarse meshes can produce accurate FE solutions because numerical dispersion errors of tetrahedral meshes do not accumulate but oscillates. In contrast, central regions of the wireframes are discretized with fine tetrahedral elements to describe complex geology in detail. The conductivity distribution is mapped from FD to FE meshes in a volume-averaged sense. To avoid excessive mesh refinement around receivers, we introduce an effective receiver size. Major advantages of FEDO are summarized as follow. First, FEDO automatically generates reliable and economic tetrahedral FE meshes without adaptive meshing or interactive CAD workflows. Second, FEDO produces FE meshes that precisely honor the boundaries of the seafloor topography. Third, FEDO derives multiple sets of FE meshes from a given FD model. Each FE mesh is optimized for a different set of sources and receivers and is fed to a subgroup of processors on a parallel computer. This divide and conquer approach improves the parallel scalability of the FE solution. Both accuracy and effectiveness of FEDO are demonstrated with various CSEM examples.
An Automatic 3D Mesh Generation Method for Domains with Multiple Materials ★
Zhang, Yongjie; Hughes, Thomas J.R.; Bajaj, Chandrajit L.
2009-01-01
This paper describes an automatic and efficient approach to construct unstructured tetrahedral and hexahedral meshes for a composite domain made up of heterogeneous materials. The boundaries of these material regions form non-manifold surfaces. In earlier papers, we developed an octree-based isocontouring method to construct unstructured 3D meshes for a single-material (homogeneous) domain with manifold boundary. In this paper, we introduce the notion of a material change edge and use it to identify the interface between two or several different materials. A novel method to calculate the minimizer point for a cell shared by more than two materials is provided, which forms a non-manifold node on the boundary. We then mesh all the material regions simultaneously and automatically while conforming to their boundaries directly from volumetric data. Both material change edges and interior edges are analyzed to construct tetrahedral meshes, and interior grid points are analyzed for proper hexahedral mesh construction. Finally, edge-contraction and smoothing methods are used to improve the quality of tetrahedral meshes, and a combination of pillowing, geometric flow and optimization techniques is used for hexahedral mesh quality improvement. The shrink set of pillowing schemes is defined automatically as the boundary of each material region. Several application results of our multi-material mesh generation method are also provided. PMID:20161555
Unstructured 3D Delaunay mesh generation applied to planes, trains and automobiles
NASA Technical Reports Server (NTRS)
Blake, Kenneth R.; Spragle, Gregory S.
1993-01-01
Technical issues associated with domain-tessellation production, including initial boundary node triangulation and volume mesh refinement, are presented for the 'TGrid' 3D Delaunay unstructured grid generation program. The approach employed is noted to be capable of preserving predefined triangular surface facets in the final tessellation. The capabilities of the approach are demonstrated by generating grids about an entire fighter aircraft configuration, a train, and a wind tunnel model of an automobile.
Mesh Generation and Microstructure Extraction based on 3D Porous Medium Images
NASA Astrophysics Data System (ADS)
Liu, Y.; Xing, H.; Guan, Z.
2009-12-01
With the development of SEM and/or MRI based techniques, it is increasingly easy to get the high quality 3D images of porous medium with the microscopic structure information. Once the pixel information for a block of porous medium is obtained, a point array description for this porous medium is defined, and both coordination and material property information are included. To analyze such related data and apply them into the further numerical modeling, a mesh generator is developed. It has following steps: (1) Reading data from a 3D image with material property/microstructure information and extracting points with the specified material property; (2) Performing a well-known Delaunay triangulation on the related points and constraining the boundary of different materials; (3) Extracting boundary which describes the microscopic structure of porous medium; (4) Smoothing boundary based on Curvature and shape of the porous medium including mesh coarsening/refining. (5) Using the smoothed boundary as an input closed triangular surface and taking a constrained Delaunay triangulation based on this surface; (6) Adaptively refining the generated tetrahedron and transporting the property of porous medium to the related tetrahedrons; (7) Output the mesh for the further numerical (e.g. FEM, FDM, FVM) analysis.
Fast precalculated triangular mesh algorithm for 3D binary computer-generated holograms.
Yang, Fan; Kaczorowski, Andrzej; Wilkinson, Tim D
2014-12-10
A new method for constructing computer-generated holograms using a precalculated triangular mesh is presented. The speed of calculation can be increased dramatically by exploiting both the precalculated base triangle and GPU parallel computing. Unlike algorithms using point-based sources, this method can reconstruct a more vivid 3D object instead of a "hollow image." In addition, there is no need to do a fast Fourier transform for each 3D element every time. A ferroelectric liquid crystal spatial light modulator is used to display the binary hologram within our experiment and the hologram of a base right triangle is produced by utilizing just a one-step Fourier transform in the 2D case, which can be expanded to the 3D case by multiplying by a suitable Fresnel phase plane. All 3D holograms generated in this paper are based on Fresnel propagation; thus, the Fresnel plane is treated as a vital element in producing the hologram. A GeForce GTX 770 graphics card with 2 GB memory is used to achieve parallel computing.
Spear, Ashley D.; Hochhalter, Jacob D.; Cerrone, Albert R.; Li, Shiu Fai; Lind, Jonathan F.; Suter, Robert M.; Ingraffea, Anthony R.
2016-04-27
In an effort to reproduce computationally the observed evolution of microstructurally small fatigue cracks (MSFCs), a method is presented for generating conformal, finite-element (FE), volume meshes from 3D measurements of MSFC propagation. The resulting volume meshes contain traction-free surfaces that conform to incrementally measured 3D crack shapes. Grain morphologies measured using near-field high-energy X-ray diffraction microscopy are also represented within the FE volume meshes. Proof-of-concept simulations are performed to demonstrate the utility of the mesh-generation method. The proof-of-concept simulations employ a crystal-plasticity constitutive model and are performed using the conformal FE meshes corresponding to successive crack-growth increments. Although the simulations for each crack increment are currently independent of one another, they need not be, and transfer of material-state information among successive crack-increment meshes is discussed. The mesh-generation method was developed using post-mortem measurements, yet it is general enough that it can be applied to in-situ measurements of 3D MSFC propagation.
Spear, Ashley D.; Hochhalter, Jacob D.; Cerrone, Albert R.; ...
2016-04-27
In an effort to reproduce computationally the observed evolution of microstructurally small fatigue cracks (MSFCs), a method is presented for generating conformal, finite-element (FE), volume meshes from 3D measurements of MSFC propagation. The resulting volume meshes contain traction-free surfaces that conform to incrementally measured 3D crack shapes. Grain morphologies measured using near-field high-energy X-ray diffraction microscopy are also represented within the FE volume meshes. Proof-of-concept simulations are performed to demonstrate the utility of the mesh-generation method. The proof-of-concept simulations employ a crystal-plasticity constitutive model and are performed using the conformal FE meshes corresponding to successive crack-growth increments. Although the simulationsmore » for each crack increment are currently independent of one another, they need not be, and transfer of material-state information among successive crack-increment meshes is discussed. The mesh-generation method was developed using post-mortem measurements, yet it is general enough that it can be applied to in-situ measurements of 3D MSFC propagation.« less
3D active shape models of human brain structures: application to patient-specific mesh generation
NASA Astrophysics Data System (ADS)
Ravikumar, Nishant; Castro-Mateos, Isaac; Pozo, Jose M.; Frangi, Alejandro F.; Taylor, Zeike A.
2015-03-01
The use of biomechanics-based numerical simulations has attracted growing interest in recent years for computer-aided diagnosis and treatment planning. With this in mind, a method for automatic mesh generation of brain structures of interest, using statistical models of shape (SSM) and appearance (SAM), for personalised computational modelling is presented. SSMs are constructed as point distribution models (PDMs) while SAMs are trained using intensity profiles sampled from a training set of T1-weighted magnetic resonance images. The brain structures of interest are, the cortical surface (cerebrum, cerebellum & brainstem), lateral ventricles and falx-cerebri membrane. Two methods for establishing correspondences across the training set of shapes are investigated and compared (based on SSM quality): the Coherent Point Drift (CPD) point-set registration method and B-spline mesh-to-mesh registration method. The MNI-305 (Montreal Neurological Institute) average brain atlas is used to generate the template mesh, which is deformed and registered to each training case, to establish correspondence over the training set of shapes. 18 healthy patients' T1-weightedMRimages form the training set used to generate the SSM and SAM. Both model-training and model-fitting are performed over multiple brain structures simultaneously. Compactness and generalisation errors of the BSpline-SSM and CPD-SSM are evaluated and used to quantitatively compare the SSMs. Leave-one-out cross validation is used to evaluate SSM quality in terms of these measures. The mesh-based SSM is found to generalise better and is more compact, relative to the CPD-based SSM. Quality of the best-fit model instance from the trained SSMs, to test cases are evaluated using the Hausdorff distance (HD) and mean absolute surface distance (MASD) metrics.
KNUPP,PATRICK; MITCHELL,SCOTT A.
1999-11-01
In an attempt to automatically produce high-quality all-hex meshes, we investigated a mesh improvement strategy: given an initial poor-quality all-hex mesh, we iteratively changed the element connectivity, adding and deleting elements and nodes, and optimized the node positions. We found a set of hex reconnection primitives. We improved the optimization algorithms so they can untangle a negative-Jacobian mesh, even considering Jacobians on the boundary, and subsequently optimize the condition number of elements in an untangled mesh. However, even after applying both the primitives and optimization we were unable to produce high-quality meshes in certain regions. Our experiences suggest that many boundary configurations of quadrilaterals admit no hexahedral mesh with positive Jacobians, although we have no proof of this.
MeshLab: 3D triangular meshes processing and editing
NASA Astrophysics Data System (ADS)
Cignoni, P.; Callieri, M.; Corsini, M.; Dellepiane, M.; Ganovelli, F.; Ranzuglia, G.
2017-09-01
MeshLab processes and edits 3D triangular meshes. It includes tools for editing, cleaning, healing, inspecting, rendering, texturing and converting meshes, and offers features for processing raw data produced by 3D digitization tools and devices and for preparing models for 3D printing.
The 2D and 3D hypersonic flows with unstructured meshes
NASA Technical Reports Server (NTRS)
Thareja, Rajiv
1993-01-01
Viewgraphs on 2D and 3D hypersonic flows with unstructured meshes are presented. Topics covered include: mesh generation, mesh refinement, shock-shock interaction, velocity contours, mesh movement, vehicle bottom surface, and adapted meshes.
Pavarino, E.; Neves, L. A.; Machado, J. M.; de Godoy, M. F.; Shiyou, Y.; Momente, J. C.; Zafalon, G. F. D.; Pinto, A. R.; Valêncio, C. R.
2013-01-01
The Finite Element Method is a well-known technique, being extensively applied in different areas. Studies using the Finite Element Method (FEM) are targeted to improve cardiac ablation procedures. For such simulations, the finite element meshes should consider the size and histological features of the target structures. However, it is possible to verify that some methods or tools used to generate meshes of human body structures are still limited, due to nondetailed models, nontrivial preprocessing, or mainly limitation in the use condition. In this paper, alternatives are demonstrated to solid modeling and automatic generation of highly refined tetrahedral meshes, with quality compatible with other studies focused on mesh generation. The innovations presented here are strategies to integrate Open Source Software (OSS). The chosen techniques and strategies are presented and discussed, considering cardiac structures as a first application context. PMID:23762031
NASA Technical Reports Server (NTRS)
Raju, I. S.
1992-01-01
A computer program that generates three-dimensional (3D) finite element models for cracked 3D solids was written. This computer program, gensurf, uses minimal input data to generate 3D finite element models for isotropic solids with elliptic or part-elliptic cracks. These models can be used with a 3D finite element program called surf3d. This report documents this mesh generator. In this manual the capabilities, limitations, and organization of gensurf are described. The procedures used to develop 3D finite element models and the input for and the output of gensurf are explained. Several examples are included to illustrate the use of this program. Several input data files are included with this manual so that the users can edit these files to conform to their crack configuration and use them with gensurf.
[Digital modeling for the individual mandibular 3D mesh scaffold based on 3D printing technology].
Yan, Rongzeng; Luo, Danmei; Qin, Xiaoyu; Li, Runxin; Rong, Qiguo; Hu, Min
2016-05-01
To investigate an ideal modeling method of designing 3D mesh scaffold substitutes based on tissue engineering to restore mandibular bone defects. By analyzing the theoretical model from titanium scaffolds fabricated by 3D printing, the feasibility and effectiveness of the proposed methodology were verified. Based on the CT scanned data of a subject, the Mimics 15.0 and Geomagic studio 12.0 reverse engineering software were adopted to generate surface model of mandibular bone and the defect area was separated from the 3D model of bone. Then prosthesis was designed via mirror algorithm, in which outer shape was used as the external shape of scaffold. Unigraphics software NX 8.5 was applied on Boolean calculation of subtraction between prosthesis and regular microstructure structure and ANSYS 14.0 software was used to design the inner construction of 3D mesh scaffolds. The topological structure and the geometrical parameters of 3D mesh titanium scaffolds were adjusted according to the aim of optimized structure and maximal strength with minimal weight. The 3D mesh scaffolds solid model through two kinds of computer-aided methods was input into 3D printing equipment to fabricate titanium scaffolds. Individual scaffolds were designed successfully by two modeling methods. The finite element optimization made 10% decrease of the stress peak and volume decrease of 43%, and the porosity increased to 76.32%. This modeling method was validated by 3D printing titanium scaffold to be feasible and effective. 3D printing technology combined with finite element topology optimization to obtain the ideal mandibular 3D mesh scaffold is feasible and effective.
Cerutti, Guillaume; Ali, Olivier; Godin, Christophe
2017-01-01
Context: The shoot apical meristem (SAM), origin of all aerial organs of the plant, is a restricted niche of stem cells whose growth is regulated by a complex network of genetic, hormonal and mechanical interactions. Studying the development of this area at cell level using 3D microscopy time-lapse imaging is a newly emerging key to understand the processes controlling plant morphogenesis. Computational models have been proposed to simulate those mechanisms, however their validation on real-life data is an essential step that requires an adequate representation of the growing tissue to be carried out. Achievements: The tool we introduce is a two-stage computational pipeline that generates a complete 3D triangular mesh of the tissue volume based on a segmented tissue image stack. DRACO (Dual Reconstruction by Adjacency Complex Optimization) is designed to retrieve the underlying 3D topological structure of the tissue and compute its dual geometry, while STEM (SAM Tissue Enhanced Mesh) returns a faithful triangular mesh optimized along several quality criteria (intrinsic quality, tissue reconstruction, visual adequacy). Quantitative evaluation tools measuring the performance of the method along those different dimensions are also provided. The resulting meshes can be used as input and validation for biomechanical simulations. Availability: DRACO-STEM is supplied as a package of the open-source multi-platform plant modeling library OpenAlea (http://openalea.github.io/) implemented in Python, and is freely distributed on GitHub (https://github.com/VirtualPlants/draco-stem) along with guidelines for installation and use.
Cerutti, Guillaume; Ali, Olivier; Godin, Christophe
2017-01-01
Context: The shoot apical meristem (SAM), origin of all aerial organs of the plant, is a restricted niche of stem cells whose growth is regulated by a complex network of genetic, hormonal and mechanical interactions. Studying the development of this area at cell level using 3D microscopy time-lapse imaging is a newly emerging key to understand the processes controlling plant morphogenesis. Computational models have been proposed to simulate those mechanisms, however their validation on real-life data is an essential step that requires an adequate representation of the growing tissue to be carried out. Achievements: The tool we introduce is a two-stage computational pipeline that generates a complete 3D triangular mesh of the tissue volume based on a segmented tissue image stack. DRACO (Dual Reconstruction by Adjacency Complex Optimization) is designed to retrieve the underlying 3D topological structure of the tissue and compute its dual geometry, while STEM (SAM Tissue Enhanced Mesh) returns a faithful triangular mesh optimized along several quality criteria (intrinsic quality, tissue reconstruction, visual adequacy). Quantitative evaluation tools measuring the performance of the method along those different dimensions are also provided. The resulting meshes can be used as input and validation for biomechanical simulations. Availability: DRACO-STEM is supplied as a package of the open-source multi-platform plant modeling library OpenAlea (http://openalea.github.io/) implemented in Python, and is freely distributed on GitHub (https://github.com/VirtualPlants/draco-stem) along with guidelines for installation and use. PMID:28424704
3D Finite Element Meshing of Stromboli and Mount Etna
NASA Astrophysics Data System (ADS)
Cianetti, S.; Casarotti, E.; Giunchi, C.
2008-12-01
The development of monitoring networks both at Mount Etna and Stromboli provided a fairly detailed database of geodetic and seismological observations during the unrest and eruptive/explosive phases of the last few years. These data reveal a tight interaction between magmatic and seismic activities. Their interpretation requires a new generation of numerical models of the volcanic edifices, based on the finite element method and characterized by realistic topography, anelastic rheology, internal discontinuities and lateral variations of mechanical parameters. We focus on the problem to make a flawless spatial discretization, which is an essential step for an accurate finite element simulation. If 3D unstructured tetrahedral meshes can be achieved quite easily with commercial or non-commercial algorithms, the creation of 3D non-structured hexahedral meshes is still recognized as a challenging issue. For complex models, as in the case of realistic geological volumes, generating a hexahedral mesh with the available meshing algorithms can require weeks or even months. Nevertheless, all-hexahedral meshes are still eagerly requested and, in some cases, preferred to all-tetrahedral ones, mainly because of the superior numerical accuracy and stability, but also for the lower computational cost. Taking advantage of CUBIT (www.cubit.sandia.gov) and of the expertise acquired in the meshing process for seismological problem, we present the mesh of the two most active italian volcanoes: Stromboli and Mount Etna. The grids are based upon updated and detailed digital elevation models with a resolution of tenth of meters in the zones where the most significant deformations are observed and include the major structural discontinuities. An unstructured scheme is implemented in order to obtain a lower resolution away from the volcano summit.
An efficient and robust 3D mesh compression based on 3D watermarking and wavelet transform
NASA Astrophysics Data System (ADS)
Zagrouba, Ezzeddine; Ben Jabra, Saoussen; Didi, Yosra
2011-06-01
The compression and watermarking of 3D meshes are very important in many areas of activity including digital cinematography, virtual reality as well as CAD design. However, most studies on 3D watermarking and 3D compression are done independently. To verify a good trade-off between protection and a fast transfer of 3D meshes, this paper proposes a new approach which combines 3D mesh compression with mesh watermarking. This combination is based on a wavelet transformation. In fact, the used compression method is decomposed to two stages: geometric encoding and topologic encoding. The proposed approach consists to insert a signature between these two stages. First, the wavelet transformation is applied to the original mesh to obtain two components: wavelets coefficients and a coarse mesh. Then, the geometric encoding is done on these two components. The obtained coarse mesh will be marked using a robust mesh watermarking scheme. This insertion into coarse mesh allows obtaining high robustness to several attacks. Finally, the topologic encoding is applied to the marked coarse mesh to obtain the compressed mesh. The combination of compression and watermarking permits to detect the presence of signature after a compression of the marked mesh. In plus, it allows transferring protected 3D meshes with the minimum size. The experiments and evaluations show that the proposed approach presents efficient results in terms of compression gain, invisibility and robustness of the signature against of many attacks.
3D Finite Element Trajectory Code with Adaptive Meshing
NASA Astrophysics Data System (ADS)
Ives, Lawrence; Bui, Thuc; Vogler, William; Bauer, Andy; Shephard, Mark; Beal, Mark; Tran, Hien
2004-11-01
Beam Optics Analysis, a new, 3D charged particle program is available and in use for the design of complex, 3D electron guns and charged particle devices. The code reads files directly from most CAD and solid modeling programs, includes an intuitive Graphical User Interface (GUI), and a robust mesh generator that is fully automatic. Complex problems can be set up, and analysis initiated in minutes. The program includes a user-friendly post processor for displaying field and trajectory data using 3D plots and images. The electrostatic solver is based on the standard nodal finite element method. The magnetostatic field solver is based on the vector finite element method and is also called during the trajectory simulation process to solve for self magnetic fields. The user imports the geometry from essentially any commercial CAD program and uses the GUI to assign parameters (voltages, currents, dielectric constant) and designate emitters (including work function, emitter temperature, and number of trajectories). The the mesh is generated automatically and analysis is performed, including mesh adaptation to improve accuracy and optimize computational resources. This presentation will provide information on the basic structure of the code, its operation, and it's capabilities.
LayTracks3D: A new approach for meshing general solids using medial axis transform
Quadros, William Roshan
2015-08-22
This study presents an extension of the all-quad meshing algorithm called LayTracks to generate high quality hex-dominant meshes of general solids. LayTracks3D uses the mapping between the Medial Axis (MA) and the boundary of the 3D domain to decompose complex 3D domains into simpler domains called Tracks. Tracks in 3D have no branches and are symmetric, non-intersecting, orthogonal to the boundary, and the shortest path from the MA to the boundary. These properties of tracks result in desired meshes with near cube shape elements at the boundary, structured mesh along the boundary normal with any irregular nodes restricted to the MA, and sharp boundary feature preservation. The algorithm has been tested on a few industrial CAD models and hex-dominant meshes are shown in the Results section. Work is underway to extend LayTracks3D to generate all-hex meshes.
3D-Meshes aus medizinischen Volumendaten
NASA Astrophysics Data System (ADS)
Zelzer, Sascha; Meinzer, Hans-Peter
Diese Arbeit beschreibt eine template-basierte Methode zur Erzeugung von adaptiven Hexaeder-Meshes aus Volumendaten, welche komplizierte konkave Strukturen aufweisen können. Es wird ein vollständiger Satz von Templates generiert der es erlaubt, die Ränder konkaver Regionen feiner zu zerlegen als angrenzende Bereiche und somit die Gesamtzahl an Hexaeder verringert. Der Algorithmus arbeitet mit beliebigen gelabelten Volumendaten und erzeugt ein adaptives, konformes, reines Hexaeder-Mesh.
Spherical geodesic mesh generation
Fung, Jimmy; Kenamond, Mark Andrew; Burton, Donald E.; Shashkov, Mikhail Jurievich
2015-02-27
In ALE simulations with moving meshes, mesh topology has a direct influence on feature representation and code robustness. In three-dimensional simulations, modeling spherical volumes and features is particularly challenging for a hydrodynamics code. Calculations on traditional spherical meshes (such as spin meshes) often lead to errors and symmetry breaking. Although the underlying differencing scheme may be modified to rectify this, the differencing scheme may not be accessible. This work documents the use of spherical geodesic meshes to mitigate solution-mesh coupling. These meshes are generated notionally by connecting geodesic surface meshes to produce triangular-prismatic volume meshes. This mesh topology is fundamentally different from traditional mesh topologies and displays superior qualities such as topological symmetry. This work describes the geodesic mesh topology as well as motivating demonstrations with the FLAG hydrocode.
Grover, Benjamin T.; Nissen, III, Walter I.
2007-02-02
The CMG is a small, lightweight, structured mesh generation code. It features a simple text input parser that allows setup of various meshes via a small set of text commands. Mesh generation data can be output to text, the silo file format, or the API can be directly queried by applications. It can run serially or in parallel via MPI. The CMG includes the ability to specify varius initial conditions on a mesh via mesh tags.
Combining 3d Volume and Mesh Models for Representing Complicated Heritage Buildings
NASA Astrophysics Data System (ADS)
Tsai, F.; Chang, H.; Lin, Y.-W.
2017-08-01
This study developed a simple but effective strategy to combine 3D volume and mesh models for representing complicated heritage buildings and structures. The idea is to seamlessly integrate 3D parametric or polyhedral models and mesh-based digital surfaces to generate a hybrid 3D model that can take advantages of both modeling methods. The proposed hybrid model generation framework is separated into three phases. Firstly, after acquiring or generating 3D point clouds of the target, these 3D points are partitioned into different groups. Secondly, a parametric or polyhedral model of each group is generated based on plane and surface fitting algorithms to represent the basic structure of that region. A "bare-bones" model of the target can subsequently be constructed by connecting all 3D volume element models. In the third phase, the constructed bare-bones model is used as a mask to remove points enclosed by the bare-bones model from the original point clouds. The remaining points are then connected to form 3D surface mesh patches. The boundary points of each surface patch are identified and these boundary points are projected onto the surfaces of the bare-bones model. Finally, new meshes are created to connect the projected points and original mesh boundaries to integrate the mesh surfaces with the 3D volume model. The proposed method was applied to an open-source point cloud data set and point clouds of a local historical structure. Preliminary results indicated that the reconstructed hybrid models using the proposed method can retain both fundamental 3D volume characteristics and accurate geometric appearance with fine details. The reconstructed hybrid models can also be used to represent targets in different levels of detail according to user and system requirements in different applications.
Documentation for MeshKit - Reactor Geometry (&mesh) Generator
Jain, Rajeev; Mahadevan, Vijay
2015-09-30
This report gives documentation for using MeshKit’s Reactor Geometry (and mesh) Generator (RGG) GUI and also briefly documents other algorithms and tools available in MeshKit. RGG is a program designed to aid in modeling and meshing of complex/large hexagonal and rectilinear reactor cores. RGG uses Argonne’s SIGMA interfaces, Qt and VTK to produce an intuitive user interface. By integrating a 3D view of the reactor with the meshing tools and combining them into one user interface, RGG streamlines the task of preparing a simulation mesh and enables real-time feedback that reduces accidental scripting mistakes that could waste hours of meshing. RGG interfaces with MeshKit tools to consolidate the meshing process, meaning that going from model to mesh is as easy as a button click. This report is designed to explain RGG v 2.0 interface and provide users with the knowledge and skills to pilot RGG successfully. Brief documentation of MeshKit source code, tools and other algorithms available are also presented for developers to extend and add new algorithms to MeshKit. RGG tools work in serial and parallel and have been used to model complex reactor core models consisting of conical pins, load pads, several thousands of axially varying material properties of instrumentation pins and other interstices meshes.
LayTracks3D: A new approach for meshing general solids using medial axis transform
Quadros, William Roshan
2015-08-22
This study presents an extension of the all-quad meshing algorithm called LayTracks to generate high quality hex-dominant meshes of general solids. LayTracks3D uses the mapping between the Medial Axis (MA) and the boundary of the 3D domain to decompose complex 3D domains into simpler domains called Tracks. Tracks in 3D have no branches and are symmetric, non-intersecting, orthogonal to the boundary, and the shortest path from the MA to the boundary. These properties of tracks result in desired meshes with near cube shape elements at the boundary, structured mesh along the boundary normal with any irregular nodes restricted to themore » MA, and sharp boundary feature preservation. The algorithm has been tested on a few industrial CAD models and hex-dominant meshes are shown in the Results section. Work is underway to extend LayTracks3D to generate all-hex meshes.« less
3D model retrieval method based on mesh segmentation
NASA Astrophysics Data System (ADS)
Gan, Yuanchao; Tang, Yan; Zhang, Qingchen
2012-04-01
In the process of feature description and extraction, current 3D model retrieval algorithms focus on the global features of 3D models but ignore the combination of global and local features of the model. For this reason, they show less effective performance to the models with similar global shape and different local shape. This paper proposes a novel algorithm for 3D model retrieval based on mesh segmentation. The key idea is to exact the structure feature and the local shape feature of 3D models, and then to compares the similarities of the two characteristics and the total similarity between the models. A system that realizes this approach was built and tested on a database of 200 objects and achieves expected results. The results show that the proposed algorithm improves the precision and the recall rate effectively.
3D unstructured mesh discontinuous finite element hydro
Prasad, M.K.; Kershaw, D.S.; Shaw, M.J.
1995-07-01
The authors present detailed features of the ICF3D hydrodynamics code used for inertial fusion simulations. This code is intended to be a state-of-the-art upgrade of the well-known fluid code, LASNEX. ICF3D employs discontinuous finite elements on a discrete unstructured mesh consisting of a variety of 3D polyhedra including tetrahedra, prisms, and hexahedra. The authors discussed details of how the ROE-averaged second-order convection was applied on the discrete elements, and how the C++ coding interface has helped to simplify implementing the many physics and numerics modules within the code package. The author emphasized the virtues of object-oriented design in large scale projects such as ICF3D.
Hough transform-based 3D mesh retrieval
NASA Astrophysics Data System (ADS)
Zaharia, Titus; Preteux, Francoise J.
2001-11-01
This papre addresses the issue of 3D mesh indexation by using shape descriptors (SDs) under constraints of geometric and topological invariance. A new shape descriptor, the Optimized 3D Hough Transform Descriptor (O3HTD) is here proposed. Intrinsically topologically stable, the O3DHTD is not invariant to geometric transformations. Nevertheless, we show mathematically how the O3DHTD can be optimally associated (in terms of compactness of representation and computational complexity) with a spatial alignment procedure which leads to a geometric invariant behavior. Experimental results have been carried out upon the MPEG-7 3D model database consisting of about 1300 meshes in VRML 2.0 format. Objective retrieval results, based upon the definition of a categorized ground truth subset, are reported in terms of Bull Eye Percentage (BEP) score and compared to those obtained by applying the MPEg-7 3D SD. It is shown that the O3DHTD outperforms the MPEg-7 3D SD of up to 28%.
Parallel 3D Mortar Element Method for Adaptive Nonconforming Meshes
NASA Technical Reports Server (NTRS)
Feng, Huiyu; Mavriplis, Catherine; VanderWijngaart, Rob; Biswas, Rupak
2004-01-01
High order methods are frequently used in computational simulation for their high accuracy. An efficient way to avoid unnecessary computation in smooth regions of the solution is to use adaptive meshes which employ fine grids only in areas where they are needed. Nonconforming spectral elements allow the grid to be flexibly adjusted to satisfy the computational accuracy requirements. The method is suitable for computational simulations of unsteady problems with very disparate length scales or unsteady moving features, such as heat transfer, fluid dynamics or flame combustion. In this work, we select the Mark Element Method (MEM) to handle the non-conforming interfaces between elements. A new technique is introduced to efficiently implement MEM in 3-D nonconforming meshes. By introducing an "intermediate mortar", the proposed method decomposes the projection between 3-D elements and mortars into two steps. In each step, projection matrices derived in 2-D are used. The two-step method avoids explicitly forming/deriving large projection matrices for 3-D meshes, and also helps to simplify the implementation. This new technique can be used for both h- and p-type adaptation. This method is applied to an unsteady 3-D moving heat source problem. With our new MEM implementation, mesh adaptation is able to efficiently refine the grid near the heat source and coarsen the grid once the heat source passes. The savings in computational work resulting from the dynamic mesh adaptation is demonstrated by the reduction of the the number of elements used and CPU time spent. MEM and mesh adaptation, respectively, bring irregularity and dynamics to the computer memory access pattern. Hence, they provide a good way to gauge the performance of computer systems when running scientific applications whose memory access patterns are irregular and unpredictable. We select a 3-D moving heat source problem as the Unstructured Adaptive (UA) grid benchmark, a new component of the NAS Parallel
Parallel 3D Mortar Element Method for Adaptive Nonconforming Meshes
NASA Technical Reports Server (NTRS)
Feng, Huiyu; Mavriplis, Catherine; VanderWijngaart, Rob; Biswas, Rupak
2004-01-01
High order methods are frequently used in computational simulation for their high accuracy. An efficient way to avoid unnecessary computation in smooth regions of the solution is to use adaptive meshes which employ fine grids only in areas where they are needed. Nonconforming spectral elements allow the grid to be flexibly adjusted to satisfy the computational accuracy requirements. The method is suitable for computational simulations of unsteady problems with very disparate length scales or unsteady moving features, such as heat transfer, fluid dynamics or flame combustion. In this work, we select the Mark Element Method (MEM) to handle the non-conforming interfaces between elements. A new technique is introduced to efficiently implement MEM in 3-D nonconforming meshes. By introducing an "intermediate mortar", the proposed method decomposes the projection between 3-D elements and mortars into two steps. In each step, projection matrices derived in 2-D are used. The two-step method avoids explicitly forming/deriving large projection matrices for 3-D meshes, and also helps to simplify the implementation. This new technique can be used for both h- and p-type adaptation. This method is applied to an unsteady 3-D moving heat source problem. With our new MEM implementation, mesh adaptation is able to efficiently refine the grid near the heat source and coarsen the grid once the heat source passes. The savings in computational work resulting from the dynamic mesh adaptation is demonstrated by the reduction of the the number of elements used and CPU time spent. MEM and mesh adaptation, respectively, bring irregularity and dynamics to the computer memory access pattern. Hence, they provide a good way to gauge the performance of computer systems when running scientific applications whose memory access patterns are irregular and unpredictable. We select a 3-D moving heat source problem as the Unstructured Adaptive (UA) grid benchmark, a new component of the NAS Parallel
Advanced numerical methods in mesh generation and mesh adaptation
Lipnikov, Konstantine; Danilov, A; Vassilevski, Y; Agonzal, A
2010-01-01
-based error estimates. We conclude that the quasi-optimal mesh must be quasi-uniform in this metric. All numerical experiments are based on the publicly available Ani3D package, the collection of advanced numerical instruments.
A Mechanistic Study of Wetting Superhydrophobic Porous 3D Meshes.
Yohe, Stefan T; Freedman, Jonathan D; Falde, Eric J; Colson, Yolonda L; Grinstaff, Mark W
2013-08-07
Superhydrophobic, porous, 3D materials composed of poly( ε -caprolactone) (PCL) and the hydrophobic polymer dopant poly(glycerol monostearate- co- ε -caprolactone) (PGC-C18) are fabricated using the electrospinning technique. These 3D materials are distinct from 2D superhydrophobic surfaces, with maintenance of air at the surface as well as within the bulk of the material. These superhydrophobic materials float in water, and when held underwater and pressed, an air bubble is released and will rise to the surface. By changing the PGC-C18 doping concentration in the meshes and/or the fiber size from the micro- to nanoscale, the long-term stability of the entrapped air layer is controlled. The rate of water infiltration into the meshes, and the resulting displacement of the entrapped air, is quantitatively measured using X-ray computed tomography. The properties of the meshes are further probed using surfactants and solvents of different surface tensions. Finally, the application of hydraulic pressure is used to quantify the breakthrough pressure to wet the meshes. The tools for fabrication and analysis of these superhydrophobic materials as well as the ability to control the robustness of the entrapped air layer are highly desirable for a number of existing and emerging applications.
A Mechanistic Study of Wetting Superhydrophobic Porous 3D Meshes
Yohe, Stefan T.; Freedman, Jonathan D.; Falde, Eric J.; Colson, Yolonda L.; Grinstaff, Mark W.
2014-01-01
Superhydrophobic, porous, 3D materials composed of poly( ε -caprolactone) (PCL) and the hydrophobic polymer dopant poly(glycerol monostearate-co- ε -caprolactone) (PGC-C18) are fabricated using the electrospinning technique. These 3D materials are distinct from 2D superhydrophobic surfaces, with maintenance of air at the surface as well as within the bulk of the material. These superhydrophobic materials float in water, and when held underwater and pressed, an air bubble is released and will rise to the surface. By changing the PGC-C18 doping concentration in the meshes and/or the fiber size from the micro- to nanoscale, the long-term stability of the entrapped air layer is controlled. The rate of water infiltration into the meshes, and the resulting displacement of the entrapped air, is quantitatively measured using X-ray computed tomography. The properties of the meshes are further probed using surfactants and solvents of different surface tensions. Finally, the application of hydraulic pressure is used to quantify the breakthrough pressure to wet the meshes. The tools for fabrication and analysis of these superhydrophobic materials as well as the ability to control the robustness of the entrapped air layer are highly desirable for a number of existing and emerging applications. PMID:25309305
A skinning prediction scheme for dynamic 3D mesh compression
NASA Astrophysics Data System (ADS)
Mamou, Khaled; Zaharia, Titus; Prêteux, Françoise
2006-08-01
This paper presents a new prediction-based compression technique for dynamic 3D meshes with constant connectivity and time-varying geometry. The core of the proposed algorithm is a skinning model used for motion compensation. The mesh is first partitioned within vertex clusters that can be described by a single affine motion model. The proposed segmentation technique automatically determines the number of clusters and relays on a decimation strategy privileging the simplification of vertices exhibiting the same affine motion over the whole animation sequence. The residual prediction errors are finally compressed using a temporal-DCT representation. The performances of our encoder are objectively evaluated on a data set of eight animation sequences with various sizes, geometries and topologies, and exhibiting both rigid and elastic motions. The experimental evaluation shows that the proposed compression scheme outperforms state of the art techniques such as MPEG-4/AFX, Dynapack, RT, GV, MCGV, TDCT, PCA and RT compression schemes.
Unstructured mesh generation and adaptivity
NASA Technical Reports Server (NTRS)
Mavriplis, D. J.
1995-01-01
An overview of current unstructured mesh generation and adaptivity techniques is given. Basic building blocks taken from the field of computational geometry are first described. Various practical mesh generation techniques based on these algorithms are then constructed and illustrated with examples. Issues of adaptive meshing and stretched mesh generation for anisotropic problems are treated in subsequent sections. The presentation is organized in an education manner, for readers familiar with computational fluid dynamics, wishing to learn more about current unstructured mesh techniques.
Conservative Patch Algorithm and Mesh Sequencing for PAB3D
NASA Technical Reports Server (NTRS)
Pao, S. P.; Abdol-Hamid, K. S.
2005-01-01
A mesh-sequencing algorithm and a conservative patched-grid-interface algorithm (hereafter Patch Algorithm ) have been incorporated into the PAB3D code, which is a computer program that solves the Navier-Stokes equations for the simulation of subsonic, transonic, or supersonic flows surrounding an aircraft or other complex aerodynamic shapes. These algorithms are efficient, flexible, and have added tremendously to the capabilities of PAB3D. The mesh-sequencing algorithm makes it possible to perform preliminary computations using only a fraction of the grid cells (provided the original cell count is divisible by an integer) along any grid coordinate axis, independently of the other axes. The patch algorithm addresses another critical need in multi-block grid situation where the cell faces of adjacent grid blocks may not coincide, leading to errors in calculating fluxes of conserved physical quantities across interfaces between the blocks. The patch algorithm, based on the Stokes integral formulation of the applicable conservation laws, effectively matches each of the interfacial cells on one side of the block interface to the corresponding fractional cell area pieces on the other side. This approach is comprehensive and unified such that all interface topology is automatically processed without user intervention. This algorithm is implemented in a preprocessing code that creates a cell-by-cell database that will maintain flux conservation at any level of full or reduced grid density as the user may choose by way of the mesh-sequencing algorithm. These two algorithms have enhanced the numerical accuracy of the code, reduced the time and effort for grid preprocessing, and provided users with the flexibility of performing computations at any desired full or reduced grid resolution to suit their specific computational requirements.
Composite mesh generator for CFD problems
NASA Astrophysics Data System (ADS)
Kalinin, E. I.; Mazo, A. B.; Isaev, S. A.
2016-11-01
In present paper a brief introduction of HybMesh grid generator which uses composite approach is given. The process of complicated area meshing using HybMesh generator consists of sequential building structured prototype grids in relatively simple geometry, mapping them to a non-regular domains and superposing to assemble resulting grid. Transitional areas between two superposed low level grids are filled with triangular cells. Currently only 2D algorithms of such approach are implemented; 3D grids can only be restored as a result of extrusion or revolution of 2D objects.
3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes
Guo, Xiaohu; Cai, Yiqi; Yang, Yin; Wang, Jing; Jia, Xun
2016-01-01
By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes. PMID:27019849
3D-2D Deformable Image Registration Using Feature-Based Nonuniform Meshes.
Zhong, Zichun; Guo, Xiaohu; Cai, Yiqi; Yang, Yin; Wang, Jing; Jia, Xun; Mao, Weihua
2016-01-01
By using prior information of planning CT images and feature-based nonuniform meshes, this paper demonstrates that volumetric images can be efficiently registered with a very small portion of 2D projection images of a Cone-Beam Computed Tomography (CBCT) scan. After a density field is computed based on the extracted feature edges from planning CT images, nonuniform tetrahedral meshes will be automatically generated to better characterize the image features according to the density field; that is, finer meshes are generated for features. The displacement vector fields (DVFs) are specified at the mesh vertices to drive the deformation of original CT images. Digitally reconstructed radiographs (DRRs) of the deformed anatomy are generated and compared with corresponding 2D projections. DVFs are optimized to minimize the objective function including differences between DRRs and projections and the regularity. To further accelerate the above 3D-2D registration, a procedure to obtain good initial deformations by deforming the volume surface to match 2D body boundary on projections has been developed. This complete method is evaluated quantitatively by using several digital phantoms and data from head and neck cancer patients. The feature-based nonuniform meshing method leads to better results than either uniform orthogonal grid or uniform tetrahedral meshes.
Polymer-Based Mesh as Supports for Multi-layered 3D Cell Culture and Assays
Simon, Karen A.; Park, Kyeng Min; Mosadegh, Bobak; Subramaniam, Anand Bala; Mazzeo, Aaron; Ngo, Phil M.; Whitesides, George M.
2013-01-01
Three-dimensional (3D) culture systems can mimic certain aspects of the cellular microenvironment found in vivo, but generation, analysis and imaging of current model systems for 3D cellular constructs and tissues remain challenging. This work demonstrates a 3D culture system – Cells-in-Gels-in-Mesh (CiGiM) – that uses stacked sheets of polymer-based mesh to support cells embedded in gels to form tissue-like constructs; the stacked sheets can be disassembled by peeling the sheets apart to analyze cultured cells—layer-by-layer—within the construct. The mesh sheets leave openings large enough for light to pass through with minimal scattering, and thus allowing multiple options for analysis—(i) using straightforward analysis by optical light microscopy, (ii) by high-resolution analysis with fluorescence microscopy, or (iii) with a fluorescence gel scanner. The sheets can be patterned into separate zones with paraffin film-based decals, in order to conduct multiple experiments in parallel; the paraffin-based decal films also block lateral diffusion of oxygen effectively. CiGiM simplifies the generation and analysis of 3D culture without compromising throughput, and quality of the data collected: it is especially useful in experiments that require control of oxygen levels, and isolation of adjacent wells in a multi-zone format. PMID:24095253
Polymer-based mesh as supports for multi-layered 3D cell culture and assays.
Simon, Karen A; Park, Kyeng Min; Mosadegh, Bobak; Subramaniam, Anand Bala; Mazzeo, Aaron D; Ngo, Philip M; Whitesides, George M
2014-01-01
Three-dimensional (3D) culture systems can mimic certain aspects of the cellular microenvironment found in vivo, but generation, analysis and imaging of current model systems for 3D cellular constructs and tissues remain challenging. This work demonstrates a 3D culture system-Cells-in-Gels-in-Mesh (CiGiM)-that uses stacked sheets of polymer-based mesh to support cells embedded in gels to form tissue-like constructs; the stacked sheets can be disassembled by peeling the sheets apart to analyze cultured cells-layer-by-layer-within the construct. The mesh sheets leave openings large enough for light to pass through with minimal scattering, and thus allowing multiple options for analysis-(i) using straightforward analysis by optical light microscopy, (ii) by high-resolution analysis with fluorescence microscopy, or (iii) with a fluorescence gel scanner. The sheets can be patterned into separate zones with paraffin film-based decals, in order to conduct multiple experiments in parallel; the paraffin-based decal films also block lateral diffusion of oxygen effectively. CiGiM simplifies the generation and analysis of 3D culture without compromising throughput, and quality of the data collected: it is especially useful in experiments that require control of oxygen levels, and isolation of adjacent wells in a multi-zone format.
3D Compressible Melt Transport with Adaptive Mesh Refinement
NASA Astrophysics Data System (ADS)
Dannberg, Juliane; Heister, Timo
2015-04-01
Melt generation and migration have been the subject of numerous investigations, but their typical time and length-scales are vastly different from mantle convection, which makes it difficult to study these processes in a unified framework. The equations that describe coupled Stokes-Darcy flow have been derived a long time ago and they have been successfully implemented and applied in numerical models (Keller et al., 2013). However, modelling magma dynamics poses the challenge of highly non-linear and spatially variable material properties, in particular the viscosity. Applying adaptive mesh refinement to this type of problems is particularly advantageous, as the resolution can be increased in mesh cells where melt is present and viscosity gradients are high, whereas a lower resolution is sufficient in regions without melt. In addition, previous models neglect the compressibility of both the solid and the fluid phase. However, experiments have shown that the melt density change from the depth of melt generation to the surface leads to a volume increase of up to 20%. Considering these volume changes in both phases also ensures self-consistency of models that strive to link melt generation to processes in the deeper mantle, where the compressibility of the solid phase becomes more important. We describe our extension of the finite-element mantle convection code ASPECT (Kronbichler et al., 2012) that allows for solving additional equations describing the behaviour of silicate melt percolating through and interacting with a viscously deforming host rock. We use the original compressible formulation of the McKenzie equations, augmented by an equation for the conservation of energy. This approach includes both melt migration and melt generation with the accompanying latent heat effects. We evaluate the functionality and potential of this method using a series of simple model setups and benchmarks, comparing results of the compressible and incompressible formulation and
RUNTHRU6.0. Translation, Enhancement, Filtering, and Visualization of Large 3D Triangle Mesh
Janucik, F.X.; Ross, D.M.; Sischo, K.F.
1997-01-01
The runthru system consists of five programs: workcell filter, just do it, transl8g, decim8, and runthru. The workcell filter program is useful if the source of your 3D triangle mesh model is IGRIP. It will traverse a directory structure of Deneb IGRIP files and filter out any IGRIP part files that are not referenced by an accompanying IGRIP work cell file. The just do it program automates translating and/or filtering of large numbers of parts that are organized in hierarchical directory structures. The transl8g program facilitates the interchange, topology generation, error checking, and enhancement of large 3D triangle meshes. Such data is frequently used to represent conceptual designs, scientific visualization volume modeling, or discrete sample data. Interchange is provided between several popular commercial and defacto standard geometry formats. Error checking is included to identify duplicate and zero area triangles. Model engancement features include common vertex joining, consistent triangle vertex ordering, vertex noemal vector averaging, and triangle strip generation. Many of the traditional O(n2) algorithms required to provide the above features have been recast and are o(nlog(n)) which support large mesh sizes. The decim8 program is based on a data filter algorithm that significantly reduces the number of triangles required to represent 3D models of geometry, scientific visualization results, and discretely sampled data. It eliminates local patches of triangles whose geometries are not appreciably different and replaces them with fewer, larger triangles. The algorithm has been used to reduce triangles in large conceptual design models to facilitate virtual walk throughs and to enable interactive viewing of large 3D iso-surface volume visualizations. The runthru program provides high performance interactive display and manipulation of 3D triangle mesh models.
Surface Generation and Cartesian Mesh Support
NASA Technical Reports Server (NTRS)
Haimes, Robert
2004-01-01
This document serves as the final report for the grant titled Surface Generation and Cartesian Mesh Support . This completed work was in algorithmic research into automatically generating surface triangulations from CAD geometries. NASA's OVERFLOW and Cart3D simulation packages use surface triangulations as an underlying geometry description and the ability to automatically generate these from CAD files (without translation) substantially reduces both the wall-clock time and expertise required to get geometry out of CAD and into mesh generation. This surface meshing was exercised greatly during the Shuttle investigation during the last year with success. The secondary efforts performed in this grant involve work on a visualization system cut-cell handling for Cartesian Meshes with embedded boundaries.
Parallel adaptive mesh refinement within the PUMAA3D Project
NASA Technical Reports Server (NTRS)
Freitag, Lori; Jones, Mark; Plassmann, Paul
1995-01-01
To enable the solution of large-scale applications on distributed memory architectures, we are designing and implementing parallel algorithms for the fundamental tasks of unstructured mesh computation. In this paper, we discuss efficient algorithms developed for two of these tasks: parallel adaptive mesh refinement and mesh partitioning. The algorithms are discussed in the context of two-dimensional finite element solution on triangular meshes, but are suitable for use with a variety of element types and with h- or p-refinement. Results demonstrating the scalability and efficiency of the refinement algorithm and the quality of the mesh partitioning are presented for several test problems on the Intel DELTA.
3D level set methods for evolving fronts on tetrahedral meshes with adaptive mesh refinement
Morgan, Nathaniel Ray; Waltz, Jacob I.
2017-03-02
The level set method is commonly used to model dynamically evolving fronts and interfaces. In this work, we present new methods for evolving fronts with a specified velocity field or in the surface normal direction on 3D unstructured tetrahedral meshes with adaptive mesh refinement (AMR). The level set field is located at the nodes of the tetrahedral cells and is evolved using new upwind discretizations of Hamilton–Jacobi equations combined with a Runge–Kutta method for temporal integration. The level set field is periodically reinitialized to a signed distance function using an iterative approach with a new upwind gradient. We discuss themore » details of these level set and reinitialization methods. Results from a range of numerical test problems are presented.« less
3D level set methods for evolving fronts on tetrahedral meshes with adaptive mesh refinement
NASA Astrophysics Data System (ADS)
Morgan, Nathaniel R.; Waltz, Jacob I.
2017-05-01
The level set method is commonly used to model dynamically evolving fronts and interfaces. In this work, we present new methods for evolving fronts with a specified velocity field or in the surface normal direction on 3D unstructured tetrahedral meshes with adaptive mesh refinement (AMR). The level set field is located at the nodes of the tetrahedral cells and is evolved using new upwind discretizations of Hamilton-Jacobi equations combined with a Runge-Kutta method for temporal integration. The level set field is periodically reinitialized to a signed distance function using an iterative approach with a new upwind gradient. The details of these level set and reinitialization methods are discussed. Results from a range of numerical test problems are presented.
Semantic segmentation of 3D textured meshes for urban scene analysis
NASA Astrophysics Data System (ADS)
Rouhani, Mohammad; Lafarge, Florent; Alliez, Pierre
2017-01-01
Classifying 3D measurement data has become a core problem in photogrammetry and 3D computer vision, since the rise of modern multiview geometry techniques, combined with affordable range sensors. We introduce a Markov Random Field-based approach for segmenting textured meshes generated via multi-view stereo into urban classes of interest. The input mesh is first partitioned into small clusters, referred to as superfacets, from which geometric and photometric features are computed. A random forest is then trained to predict the class of each superfacet as well as its similarity with the neighboring superfacets. Similarity is used to assign the weights of the Markov Random Field pairwise-potential and to account for contextual information between the classes. The experimental results illustrate the efficacy and accuracy of the proposed framework.
Improving segmentation of 3D touching cell nuclei using flow tracking on surface meshes.
Li, Gang; Guo, Lei
2012-01-01
Automatic segmentation of touching cell nuclei in 3D microscopy images is of great importance in bioimage informatics and computational biology. This paper presents a novel method for improving 3D touching cell nuclei segmentation. Given binary touching nuclei by the method in Li et al. (2007), our method herein consists of several steps: surface mesh reconstruction and curvature information estimation; direction field diffusion on surface meshes; flow tracking on surface meshes; and projection of surface mesh segmentation to volumetric images. The method is validated on both synthesised and real 3D touching cell nuclei images, demonstrating its validity and effectiveness.
3D Mesh Segmentation Based on Markov Random Fields and Graph Cuts
NASA Astrophysics Data System (ADS)
Shi, Zhenfeng; Le, Dan; Yu, Liyang; Niu, Xiamu
3D Mesh segmentation has become an important research field in computer graphics during the past few decades. Many geometry based and semantic oriented approaches for 3D mesh segmentation has been presented. However, only a few algorithms based on Markov Random Field (MRF) has been presented for 3D object segmentation. In this letter, we present a definition of mesh segmentation according to the labeling problem. Inspired by the capability of MRF combining the geometric information and the topology information of a 3D mesh, we propose a novel 3D mesh segmentation model based on MRF and Graph Cuts. Experimental results show that our MRF-based schema achieves an effective segmentation.
A 3-D upwind Euler solver for unstructured meshes
NASA Technical Reports Server (NTRS)
Barth, Timothy J.
1991-01-01
A three-dimensional finite-volume upwind Euler solver is developed for unstructured meshes. The finite-volume scheme solves for solution variables at vertices of the mesh and satisfies the integral conservation law on nonoverlapping polyhedral control volumes surrounding vertices of the mesh. The schene achieves improved solution accuracy by assuming a piecewise linear variation of the solution in each control volume. This improved spatial accuracy hinges heavily upon the calculation of the solution gradient in each control volume given pointwise values of the solution at vertices of the mesh. Several algorithms are discussed for obtaining these gradients. Details concerning implementation procedures and data structures are discussed. Sample calculations for inviscid Euler flow about isolated aircraft wings at subsonic and transonic speeds are compared with established Euler solvers as well as experiment.
Software for Automated Generation of Cartesian Meshes
NASA Technical Reports Server (NTRS)
Aftosmis, Michael J.; Melton, John E.; Berger, Marshal J.
2006-01-01
Cart3D is a collection of computer programs for generating Cartesian meshes [for computational fluid dynamics (CFD) and other applications] in volumes bounded by solid objects. Aspects of Cart3D at earlier stages of development were reported in "Robust and Efficient Generation of Cartesian Meshes for CFD" (ARC-14275), NASA Tech Briefs, Vol. 23, No. 8 (August 1999), page 30. The geometric input to Cart3D comprises surface triangulations like those commonly generated by computer-aided-design programs. Complexly shaped objects can be represented as assemblies of simpler ones. Cart3D deletes all portions of such an assembled object that are not on the exterior surface. Intersections between components are preserved in the resulting triangulation. A tie-breaking routine unambiguously resolves geometric degeneracies. Then taking the intersected surface triangulation as input, the volume mesh is generated through division of cells of an initially coarse hexahedral grid. Cells are subdivided to refine the grid in regions of increased surface curvature and/or increased flow gradients. Cells that become split into multiple unconnected regions by thin pieces of surface are identified.
Dubai 3d Textuerd Mesh Using High Quality Resolution Vertical/oblique Aerial Imagery
NASA Astrophysics Data System (ADS)
Tayeb Madani, Adib; Ziad Ahmad, Abdullateef; Christoph, Lueken; Hammadi, Zamzam; Manal Abdullah Sabeal, Manal Abdullah x.
2016-06-01
Providing high quality 3D data with reasonable quality and cost were always essential, affording the core data and foundation for developing an information-based decision-making tool of urban environments with the capability of providing decision makers, stakeholders, professionals, and public users with 3D views and 3D analysis tools of spatial information that enables real-world views. Helps and assist in improving users' orientation and also increase their efficiency in performing their tasks related to city planning, Inspection, infrastructures, roads, and cadastre management. In this paper, the capability of multi-view Vexcel UltraCam Osprey camera images is examined to provide a 3D model of building façades using an efficient image-based modeling workflow adopted by commercial software's. The main steps of this work include: Specification, point cloud generation, and 3D modeling. After improving the initial values of interior and exterior parameters at first step, an efficient image matching technique such as Semi Global Matching (SGM) is applied on the images to generate point cloud. Then, a mesh model of points is calculated using and refined to obtain an accurate model of buildings. Finally, a texture is assigned to mesh in order to create a realistic 3D model. The resulting model has provided enough LoD2 details of the building based on visual assessment. The objective of this paper is neither comparing nor promoting a specific technique over the other and does not mean to promote a sensor-based system over another systems or mechanism presented in existing or previous paper. The idea is to share experience.
TRANSL8GDECIM8. Data Translation and Filtering for Large 3D Triangle Mesh Models
Janucik, F.X.; Ross, D.M.
1993-09-01
The TRANSL8GDECIM8 system consists of two programs: TRANSL8G and DECIM8. The TRANSL8G program facilitates the interchange, topology generation, error checking, and enhancement of large 3D triangle meshes. Such data is frequently used to represent conceptual designs, scientific visualization volume modeling, or discrete sample data. Interchange is provided between several popular commercial and defacto standard geometry formats. Error checking is included to identify duplicate and zero area triangles. Model enhancement features include common vertex joining, consistent triangle vertex ordering, vertex normal vector averaging, and triangle strip generation. Many of the traditional O(n squared) algorithms required to provide the above features have been recast and are O(n) which support large mesh sizes. The DECIM8 program is based on a data filter algorithm that significantly reduces the number of triangles required to represent three dimensional (3D) models of geometry, scientific visualization results, and discretely sampled data. The algorithm uses a combined incremental and iterative strategy. It eliminates local patches of triangles whose geometries are not appreciably different and replaces them with fewer larger triangles. The algorithm has been used to reduce triangles in large conceptual design models to facilitate virtual walk throughs and to enable interactive viewing of large 3D iso-surface volume visualizations.
Nanowire mesh solar fuels generator
Yang, Peidong; Chan, Candace; Sun, Jianwei; Liu, Bin
2016-05-24
This disclosure provides systems, methods, and apparatus related to a nanowire mesh solar fuels generator. In one aspect, a nanowire mesh solar fuels generator includes (1) a photoanode configured to perform water oxidation and (2) a photocathode configured to perform water reduction. The photocathode is in electrical contact with the photoanode. The photoanode may include a high surface area network of photoanode nanowires. The photocathode may include a high surface area network of photocathode nanowires. In some embodiments, the nanowire mesh solar fuels generator may include an ion conductive polymer infiltrating the photoanode and the photocathode in the region where the photocathode is in electrical contact with the photoanode.
Han, Zhizhong; Liu, Zhenbao; Han, Junwei; Vong, Chi-Man; Bu, Shuhui; Chen, Chun Long Philip
2016-06-30
Discriminative features of 3-D meshes are significant to many 3-D shape analysis tasks. However, handcrafted descriptors and traditional unsupervised 3-D feature learning methods suffer from several significant weaknesses: 1) the extensive human intervention is involved; 2) the local and global structure information of 3-D meshes cannot be preserved, which is in fact an important source of discriminability; 3) the irregular vertex topology and arbitrary resolution of 3-D meshes do not allow the direct application of the popular deep learning models; 4) the orientation is ambiguous on the mesh surface; and 5) the effect of rigid and nonrigid transformations on 3-D meshes cannot be eliminated. As a remedy, we propose a deep learning model with a novel irregular model structure, called mesh convolutional restricted Boltzmann machines (MCRBMs). MCRBM aims to simultaneously learn structure-preserving local and global features from a novel raw representation, local function energy distribution. In addition, multiple MCRBMs can be stacked into a deeper model, called mesh convolutional deep belief networks (MCDBNs). MCDBN employs a novel local structure preserving convolution (LSPC) strategy to convolve the geometry and the local structure learned by the lower MCRBM to the upper MCRBM. LSPC facilitates resolving the challenging issue of the orientation ambiguity on the mesh surface in MCDBN. Experiments using the proposed MCRBM and MCDBN were conducted on three common aspects: global shape retrieval, partial shape retrieval, and shape correspondence. Results show that the features learned by the proposed methods outperform the other state-of-the-art 3-D shape features.
3D unstructured-mesh radiation transport codes
Morel, J.
1997-12-31
Three unstructured-mesh radiation transport codes are currently being developed at Los Alamos National Laboratory. The first code is ATTILA, which uses an unstructured tetrahedral mesh in conjunction with standard Sn (discrete-ordinates) angular discretization, standard multigroup energy discretization, and linear-discontinuous spatial differencing. ATTILA solves the standard first-order form of the transport equation using source iteration in conjunction with diffusion-synthetic acceleration of the within-group source iterations. DANTE is designed to run primarily on workstations. The second code is DANTE, which uses a hybrid finite-element mesh consisting of arbitrary combinations of hexahedra, wedges, pyramids, and tetrahedra. DANTE solves several second-order self-adjoint forms of the transport equation including the even-parity equation, the odd-parity equation, and a new equation called the self-adjoint angular flux equation. DANTE also offers three angular discretization options: $S{_}n$ (discrete-ordinates), $P{_}n$ (spherical harmonics), and $SP{_}n$ (simplified spherical harmonics). DANTE is designed to run primarily on massively parallel message-passing machines, such as the ASCI-Blue machines at LANL and LLNL. The third code is PERICLES, which uses the same hybrid finite-element mesh as DANTE, but solves the standard first-order form of the transport equation rather than a second-order self-adjoint form. DANTE uses a standard $S{_}n$ discretization in angle in conjunction with trilinear-discontinuous spatial differencing, and diffusion-synthetic acceleration of the within-group source iterations. PERICLES was initially designed to run on workstations, but a version for massively parallel message-passing machines will be built. The three codes will be described in detail and computational results will be presented.
Generation of multi-million element meshes for solid model-based geometries: The Dicer algorithm
Melander, D.J.; Benzley, S.E.; Tautges, T.J.
1997-06-01
The Dicer algorithm generates a fine mesh by refining each element in a coarse all-hexahedral mesh generated by any existing all-hexahedral mesh generation algorithm. The fine mesh is geometry-conforming. Using existing all-hexahedral meshing algorithms to define the initial coarse mesh simplifies the overall meshing process and allows dicing to take advantage of improvements in other meshing algorithms immediately. The Dicer algorithm will be used to generate large meshes in support of the ASCI program. The authors also plan to use dicing as the basis for parallel mesh generation. Dicing strikes a careful balance between the interactive mesh generation and multi-million element mesh generation processes for complex 3D geometries, providing an efficient means for producing meshes of varying refinement once the coarse mesh is obtained.
Iterative mesh transformation for 3D segmentation of livers with cancers in CT images.
Lu, Difei; Wu, Yin; Harris, Gordon; Cai, Wenli
2015-07-01
Segmentation of diseased liver remains a challenging task in clinical applications due to the high inter-patient variability in liver shapes, sizes and pathologies caused by cancers or other liver diseases. In this paper, we present a multi-resolution mesh segmentation algorithm for 3D segmentation of livers, called iterative mesh transformation that deforms the mesh of a region-of-interest (ROI) in a progressive manner by iterations between mesh transformation and contour optimization. Mesh transformation deforms the 3D mesh based on the deformation transfer model that searches the optimal mesh based on the affine transformation subjected to a set of constraints of targeting vertices. Besides, contour optimization searches the optimal transversal contours of the ROI by applying the dynamic-programming algorithm to the intersection polylines of the 3D mesh on 2D transversal image planes. The initial constraint set for mesh transformation can be defined by a very small number of targeting vertices, namely landmarks, and progressively updated by adding the targeting vertices selected from the optimal transversal contours calculated in contour optimization. This iterative 3D mesh transformation constrained by 2D optimal transversal contours provides an efficient solution to a progressive approximation of the mesh of the targeting ROI. Based on this iterative mesh transformation algorithm, we developed a semi-automated scheme for segmentation of diseased livers with cancers using as little as five user-identified landmarks. The evaluation study demonstrates that this semi-automated liver segmentation scheme can achieve accurate and reliable segmentation results with significant reduction of interaction time and efforts when dealing with diseased liver cases.
Iterative Mesh Transformation for 3D Segmentation of Livers with Cancers in CT Images
Lu, Difei; Wu, Yin; Harris, Gordon; Cai, Wenli
2015-01-01
Segmentation of diseased liver remains a challenging task in clinical applications due to the high inter-patient variability in liver shapes, sizes and pathologies caused by cancers or other liver diseases. In this paper, we present a multi-resolution mesh segmentation algorithm for 3D segmentation of livers, called iterative mesh transformation that deforms the mesh of a region-of-interest (ROI) in a progressive manner by iterations between mesh transformation and contour optimization. Mesh transformation deforms the 3D mesh based on the deformation transfer model that searches the optimal mesh based on the affine transformation subjected to a set of constraints of targeting vertices. Besides, contour optimization searches the optimal transversal contours of the ROI by applying the dynamic-programming algorithm to the intersection polylines of the 3D mesh on 2D transversal image planes. The initial constraint set for mesh transformation can be defined by a very small number of targeting vertices, namely landmarks, and progressively updated by adding the targeting vertices selected from the optimal transversal contours calculated in contour optimization. This iterative 3D mesh transformation constrained by 2D optimal transversal contours provides an efficient solution to a progressive approximation of the mesh of the targeting ROI. Based on this iterative mesh transformation algorithm, we developed a semi-automated scheme for segmentation of diseased livers with cancers using as little as five user-identified landmarks. The evaluation study demonstrates that this semiautomated liver segmentation scheme can achieve accurate and reliable segmentation results with significant reduction of interaction time and efforts when dealing with diseased liver cases. PMID:25728595
Joint synchronization and high capacity data hiding for 3D meshes
NASA Astrophysics Data System (ADS)
Itier, Vincent; Puech, William; Gesquière, Gilles; Pedeboy, Jean-Pierre
2015-03-01
Three-dimensional (3-D) meshes are already profusely used in lot of domains. In this paper, we propose a new high capacity data hiding scheme for vertex cloud. Our approach is based on very small displacements of vertices, that produce very low distortion of the mesh. Moreover this method can embed three bits per vertex relying only on the geometry of the mesh. As an application, we show how we embed a large binary logo for copyright purpose.
Refining 3D Earth models by unifying geological and geophysical information on unstructured meshes
NASA Astrophysics Data System (ADS)
Lelièvre, P. G.; Carter-McAuslan, A.; Tycholiz, C.; Farquharson, C. G.; Hurich, C. A.
2012-04-01
Earth models used for mineral exploration or other subsurface investigations should be consistent with all available geological and geophysical information. Geophysical inversion provides the means to integrate geological information, geophysical survey data, and physical property measurements taken on rock samples. Incorporation of geological information into inversions is always an iterative process. One begins with the geologists' best guess about the Earth (i.e. the geological model) and the models recovered from geophysical inversion may indicate that the geological model should be changed slightly prior to the next iteration of the procedure. In this way, geological and geophysical data can be combined through inversion and we can move towards the creation of a common Earth model consistent with all the available data. As more information is incorporated, the inherent non-uniqueness of the inverse problem is reduced, yielding a higher potential to resolve deeper features that are less well-constrained by the geophysical data alone. Geological ore deposit models are commonly created during delineation drilling. The accuracy of these models is crucial when used to determine if a deposit is economic. 3D geological Earth models typically comprise wireframe surfaces that represent the geological contacts between different rock units. The contacts may be known at points from down-hole intersections and surface mapping, and can be interpolated between boreholes and extrapolated outwards. Contacts may also be interpreted from seismic traces. Wireframe surfaces, comprising tessellated triangular facets, are sufficiently flexible to allow the representation of arbitrarily complicated geological structures. These surfaces can be honoured exactly within fully unstructured 3D volumetric tetrahedral meshes. In contrast, geophysical forward modelling and inversion algorithms typically work with rectilinear meshes when parameterizing the subsurface because this simplifies
Grid generation for 3D turbine configurations
Reymond, J.D.; Haeuser, J.; Xia, Y.
1996-12-31
Grid generation in domains with complex geometries presents the same degree of difficulty for both internal and external flow fields. A high degree of curvature of the flow bounding surfaces results in a mesh generation process, which has to exactly describe the geometry and therefore is not straightforward. However, for internal flow problems, such as an interblade channel of a turbine, the difficulties become particularly accute when the distance between the elements is relatively small (confined domains). It often occurs that the grids generated on the different surfaces of an internal domain are incompatible producing nonsmooth grids in some areas of the flow compartment. This incompatibility problem is particularly present if the distance between opposite surfaces varies considerably along the domain.
Simplified gaze-correction method using 3D mesh warping
NASA Astrophysics Data System (ADS)
Lee, Insuh; Jeon, Byeungwoo
2000-12-01
Under the typical video communication configuration in which a camera is placed on top or at lateral side of a monitor, the face-to-face video communication has an inherent difficulty of poor eye contacts since the users stare at the monitor screen rather than directly seeing the camera lens. In this paper, we propose an image warping technique for gaze-correction which performs 3D warping of face object in the given image by a certain correction angle. The correction angle which is the angle between the direction of eye gaze and that to the camera is estimated in an unsupervised way by using eye tracking technique. Experimental results with real image data shows much enhanced naturalness which the face-to-face video communication has to offer.
Irregular Grid Generation and Rapid 3D Color Display Algorithm
Wilson D. Chin, Ph.D.
2000-05-10
Computationally efficient and fast methods for irregular grid generation are developed to accurately characterize wellbore and fracture boundaries, and farfield reservoir boundaries, in oil and gas petroleum fields. Advanced reservoir simulation techniques are developed for oilfields described by such ''boundary conforming'' mesh systems. Very rapid, three-dimensional color display algorithms are also developed that allow users to ''interrogate'' 3D earth cubes using ''slice, rotate, and zoom'' functions. Based on expert system ideas, the new methods operate much faster than existing display methodologies and do not require sophisticated computer hardware or software. They are designed to operate with PC based applications.
Curved mesh generation and mesh refinement using Lagrangian solid mechanics
Persson, P.-O.; Peraire, J.
2008-12-31
We propose a method for generating well-shaped curved unstructured meshes using a nonlinear elasticity analogy. The geometry of the domain to be meshed is represented as an elastic solid. The undeformed geometry is the initial mesh of linear triangular or tetrahedral elements. The external loading results from prescribing a boundary displacement to be that of the curved geometry, and the final configuration is determined by solving for the equilibrium configuration. The deformations are represented using piecewise polynomials within each element of the original mesh. When the mesh is sufficiently fine to resolve the solid deformation, this method guarantees non-intersecting elements even for highly distorted or anisotropic initial meshes. We describe the method and the solution procedures, and we show a number of examples of two and three dimensional simplex meshes with curved boundaries. We also demonstrate how to use the technique for local refinement of non-curved meshes in the presence of curved boundaries.
1990-03-01
Bezier , B-Splines). the general form of 3-D elliptic grid generation equations can be used taking into account the constraints represented by Eqs.(2...has its maximum slope where the curvature of u(x) has its maximum curva - ture and its minimum slope where the curvature of u(x) is also minimal The...Among the many techniques available, we mention: analytic definition (for simple geometries), Bezier -patches, and transfinite mappings. Our experience
The use of 3D-printed titanium mesh tray in treating complex comminuted mandibular fractures
Ma, Junli; Ma, Limin; Wang, Zhifa; Zhu, Xiongjie; Wang, Weijian
2017-01-01
Abstract Rationale: Precise bony reduction and reconstruction of optimal contour in treating comminuted mandibular fractures is very difficult using traditional techniques and devices. The aim of this report is to introduce our experiences in using virtual surgery and three-dimensional (3D) printing technique in treating this clinical challenge. Patient concerns: A 26-year-old man presented with severe trauma in the maxillofacial area due to fall from height. Diagnosis: Computed tomography images revealed middle face fractures and comminuted mandibular fracture including bilateral condyles. Interventions and outcomes: The computed tomography data was used to construct the 3D cranio-maxillofacial models; then the displaced bone fragments were virtually reduced. On the basis of the finalized model, a customized titanium mesh tray was designed and fabricated using selective laser melting technology. During the surgery, a submandibular approach was adopted to repair the mandibular fracture. The reduction and fixation were performed according to preoperative plan, the bone defects in the mental area were reconstructed with iliac bone graft. The 3D-printed mesh tray served as an intraoperative template and carrier of bone graft. The healing process was uneventful, and the patient was satisfied with the mandible contour. Lessons: Virtual surgical planning combined with 3D printing technology enables surgeon to visualize the reduction process preoperatively and guide intraoperative reduction, making the reduction less time consuming and more precise. 3D-printed titanium mesh tray can provide more satisfactory esthetic outcomes in treating complex comminuted mandibular fractures. PMID:28682875
NASA Astrophysics Data System (ADS)
Yang, Dikun; Oldenburg, Douglas W.; Haber, Eldad
2014-03-01
Airborne electromagnetic (AEM) methods are highly efficient tools for assessing the Earth's conductivity structures in a large area at low cost. However, the configuration of AEM measurements, which typically have widely distributed transmitter-receiver pairs, makes the rigorous modelling and interpretation extremely time-consuming in 3-D. Excessive overcomputing can occur when working on a large mesh covering the entire survey area and inverting all soundings in the data set. We propose two improvements. The first is to use a locally optimized mesh for each AEM sounding for the forward modelling and calculation of sensitivity. This dedicated local mesh is small with fine cells near the sounding location and coarse cells far away in accordance with EM diffusion and the geometric decay of the signals. Once the forward problem is solved on the local meshes, the sensitivity for the inversion on the global mesh is available through quick interpolation. Using local meshes for AEM forward modelling avoids unnecessary computing on fine cells on a global mesh that are far away from the sounding location. Since local meshes are highly independent, the forward modelling can be efficiently parallelized over an array of processors. The second improvement is random and dynamic down-sampling of the soundings. Each inversion iteration only uses a random subset of the soundings, and the subset is reselected for every iteration. The number of soundings in the random subset, determined by an adaptive algorithm, is tied to the degree of model regularization. This minimizes the overcomputing caused by working with redundant soundings. Our methods are compared against conventional methods and tested with a synthetic example. We also invert a field data set that was previously considered to be too large to be practically inverted in 3-D. These examples show that our methodology can dramatically reduce the processing time of 3-D inversion to a practical level without losing resolution
Hybrid mesh generation using advancing reduction technique
USDA-ARS?s Scientific Manuscript database
This study presents an extension of the application of the advancing reduction technique to the hybrid mesh generation. The proposed algorithm is based on a pre-generated rectangle mesh (RM) with a certain orientation. The intersection points between the two sets of perpendicular mesh lines in RM an...
Multiscale mesh generation on the sphere
NASA Astrophysics Data System (ADS)
Lambrechts, Jonathan; Comblen, Richard; Legat, Vincent; Geuzaine, Christophe; Remacle, Jean-François
2008-12-01
A method for generating computational meshes for applications in ocean modeling is presented. The method uses a standard engineering approach for describing the geometry of the domain that requires meshing. The underlying sphere is parametrized using stereographic coordinates. Then, coastlines are described with cubic splines drawn in the stereographic parametric space. The mesh generation algorithm builds the mesh in the parametric plane using available techniques. The method enables to import coastlines from different data sets and, consequently, to build meshes of domains with highly variable length scales. The results include meshes together with numerical simulations of various kinds.
Blind robust watermarking schemes for copyright protection of 3D mesh objects.
Zafeiriou, Stefanos; Tefas, Anastasios; Pitas, Ioannis
2005-01-01
In this paper, two novel methods suitable for blind 3D mesh object watermarking applications are proposed. The first method is robust against 3D rotation, translation, and uniform scaling. The second one is robust against both geometric and mesh simplification attacks. A pseudorandom watermarking signal is cast in the 3D mesh object by deforming its vertices geometrically, without altering the vertex topology. Prior to watermark embedding and detection, the object is rotated and translated so that its center of mass and its principal component coincide with the origin and the z-axis of the Cartesian coordinate system. This geometrical transformation ensures watermark robustness to translation and rotation. Robustness to uniform scaling is achieved by restricting the vertex deformations to occur only along the r coordinate of the corresponding (r, theta, phi) spherical coordinate system. In the first method, a set of vertices that correspond to specific angles theta is used for watermark embedding. In the second method, the samples of the watermark sequence are embedded in a set of vertices that correspond to a range of angles in the theta domain in order to achieve robustness against mesh simplifications. Experimental results indicate the ability of the proposed method to deal with the aforementioned attacks.
Towards next generation 3D cameras
NASA Astrophysics Data System (ADS)
Gupta, Mohit
2017-03-01
We are in the midst of a 3D revolution. Robots enabled by 3D cameras are beginning to autonomously drive cars, perform surgeries, and manage factories. However, when deployed in the real-world, these cameras face several challenges that prevent them from measuring 3D shape reliably. These challenges include large lighting variations (bright sunlight to dark night), presence of scattering media (fog, body tissue), and optically complex materials (metal, plastic). Due to these factors, 3D imaging is often the bottleneck in widespread adoption of several key robotics technologies. I will talk about our work on developing 3D cameras based on time-of-flight and active triangulation that addresses these long-standing problems. This includes designing `all-weather' cameras that can perform high-speed 3D scanning in harsh outdoor environments, as well as cameras that recover shape of objects with challenging material properties. These cameras are, for the first time, capable of measuring detailed (<100 microns resolution) scans in extremely demanding scenarios with low-cost components. Several of these cameras are making a practical impact in industrial automation, being adopted in robotic inspection and assembly systems.
Triangular mesh establishment of 3D laser scanning data based on ellipsoidal projection
NASA Astrophysics Data System (ADS)
Zheng, De-hua; Xu, Jia; Li, Jia; Wang, Xin-sen
2011-10-01
The establishment of high quality triangular mesh is one of the key steps in 3D laser scanning data processing. Traditional triangulation algorithms have been proposed directly on the basis of adjacency relation between points in 3D space. However, when the point density is non-uniform or the noise exists, the problems such as surface hole, dough sheet overlapping and inconsistent normal appear easily. In this paper, a triangular mesh establishing algorithm based on ellipsoidal projection is proposed. After comparing the theory of ellipsoidal projection and cylindrical projection, the proposed triangular mesh establishing algorithm is analyzed in detail including basic idea and implementation method. To evaluate the performance and efficiency of the proposed algorithm, two experiments are then carried out on the 3D point cloud data of a foundation pit. The results indicate that though the computational efficiency of proposed algorithm is a little inferior to the algorithm based on cylindrical projection, the proposed algorithm is more effective for establishing point cloud of both top and bottom of the object and the original topological relation of 3D scanning points can be maintained better.
Accurate, finite-volume methods for 3D MHD on unstructured Lagrangian meshes
Barnes, D.C.; Rousculp, C.L.
1998-10-01
Previous 2D methods for magnetohydrodynamics (MHD) have contributed both to development of core code capability and to physics applications relevant to AGEX pulsed-power experiments. This strategy is being extended to 3D by development of a modular extension of an ASCI code. Extension to 3D not only increases complexity by problem size, but also introduces new physics, such as magnetic helicity transport. The authors have developed a method which incorporates all known conservation properties into the difference scheme on a Lagrangian unstructured mesh. Because the method does not depend on the mesh structure, mesh refinement is possible during a calculation to prevent the well known problem of mesh tangling. Arbitrary polyhedral cells are decomposed into tetrahedrons. The action of the magnetic vector potential, A {center_dot} {delta}l, is centered on the edges of this extended mesh. For ideal flow, this maintains {del} {center_dot} B = 0 to round-off error. Vertex forces are derived by the variation of magnetic energy with respect to vertex positions, F = {minus}{partial_derivative}W{sub B}/{partial_derivative}r. This assures symmetry as well as magnetic flux, momentum, and energy conservation. The method is local so that parallelization by domain decomposition is natural for large meshes. In addition, a simple, ideal-gas, finite pressure term has been included. The resistive diffusion part is calculated using the support operator method, to obtain an energy conservative, symmetric method on an arbitrary mesh. Implicit time difference equations are solved by preconditioned, conjugate gradient methods. Results of convergence tests are presented. Initial results of an annular Z-pinch implosion problem illustrate the application of these methods to multi-material problems.
3D meshes of carbon nanotubes guide functional reconnection of segregated spinal explants
Usmani, Sadaf; Aurand, Emily Rose; Medelin, Manuela; Fabbro, Alessandra; Scaini, Denis; Laishram, Jummi; Rosselli, Federica B.; Ansuini, Alessio; Zoccolan, Davide; Scarselli, Manuela; De Crescenzi, Maurizio; Bosi, Susanna; Prato, Maurizio; Ballerini, Laura
2016-01-01
In modern neuroscience, significant progress in developing structural scaffolds integrated with the brain is provided by the increasing use of nanomaterials. We show that a multiwalled carbon nanotube self-standing framework, consisting of a three-dimensional (3D) mesh of interconnected, conductive, pure carbon nanotubes, can guide the formation of neural webs in vitro where the spontaneous regrowth of neurite bundles is molded into a dense random net. This morphology of the fiber regrowth shaped by the 3D structure supports the successful reconnection of segregated spinal cord segments. We further observed in vivo the adaptability of these 3D devices in a healthy physiological environment. Our study shows that 3D artificial scaffolds may drive local rewiring in vitro and hold great potential for the development of future in vivo interfaces. PMID:27453939
Fruit bruise detection based on 3D meshes and machine learning technologies
NASA Astrophysics Data System (ADS)
Hu, Zilong; Tang, Jinshan; Zhang, Ping
2016-05-01
This paper studies bruise detection in apples using 3-D imaging. Bruise detection based on 3-D imaging overcomes many limitations of bruise detection based on 2-D imaging, such as low accuracy, sensitive to light condition, and so on. In this paper, apple bruise detection is divided into two parts: feature extraction and classification. For feature extraction, we use a framework that can directly extract local binary patterns from mesh data. For classification, we studies support vector machine. Bruise detection using 3-D imaging is compared with bruise detection using 2-D imaging. 10-fold cross validation is used to evaluate the performance of the two systems. Experimental results show that bruise detection using 3-D imaging can achieve better classification accuracy than bruise detection based on 2-D imaging.
3D meshes of carbon nanotubes guide functional reconnection of segregated spinal explants.
Usmani, Sadaf; Aurand, Emily Rose; Medelin, Manuela; Fabbro, Alessandra; Scaini, Denis; Laishram, Jummi; Rosselli, Federica B; Ansuini, Alessio; Zoccolan, Davide; Scarselli, Manuela; De Crescenzi, Maurizio; Bosi, Susanna; Prato, Maurizio; Ballerini, Laura
2016-07-01
In modern neuroscience, significant progress in developing structural scaffolds integrated with the brain is provided by the increasing use of nanomaterials. We show that a multiwalled carbon nanotube self-standing framework, consisting of a three-dimensional (3D) mesh of interconnected, conductive, pure carbon nanotubes, can guide the formation of neural webs in vitro where the spontaneous regrowth of neurite bundles is molded into a dense random net. This morphology of the fiber regrowth shaped by the 3D structure supports the successful reconnection of segregated spinal cord segments. We further observed in vivo the adaptability of these 3D devices in a healthy physiological environment. Our study shows that 3D artificial scaffolds may drive local rewiring in vitro and hold great potential for the development of future in vivo interfaces.
Method of generating a surface mesh
Shepherd, Jason F.; Benzley, Steven; Grover, Benjamin T.
2008-03-04
A method and machine-readable medium provide a technique to generate and modify a quadrilateral finite element surface mesh using dual creation and modification. After generating a dual of a surface (mesh), a predetermined algorithm may be followed to generate and modify a surface mesh of quadrilateral elements. The predetermined algorithm may include the steps of generating two-dimensional cell regions in dual space, determining existing nodes in primal space, generating new nodes in the dual space, and connecting nodes to form the quadrilateral elements (faces) for the generated and modifiable surface mesh.
3D unstructured mesh ALE hydrodynamics with the upwind discontinuous galerkin method
Kershaw, D S; Milovich, J L; Prasad, M K; Shaw, M J; Shestakov, A I
1999-05-07
The authors describe a numerical scheme to solve 3D Arbitrary Lagrangian-Eulerian (ALE) hydrodynamics on an unstructured mesh using a discontinuous Galerkin method (DGM) and an explicit Runge-Kutta time discretization. Upwinding is achieved through Roe's linearized Riemann solver with the Harten-Hyman entropy fix. For stabilization, a 3D quadratic programming generalization of van Leer's 1D minmod slope limiter is used along with a Lapidus type artificial viscosity. This DGM scheme has been tested on a variety of hydrodynamic test problems and appears to be robust making it the basis for the integrated 3D inertial confinement fusion modeling code (ICF3D). For efficient code development, they use C++ object oriented programming to easily separate the complexities of an unstructured mesh from the basic physics modules. ICF3D is fully parallelized using domain decomposition and the MPI message passing library. It is fully portable. It runs on uniprocessor workstations and massively parallel platforms with distributed and shared memory.
Rare meshes FEM scheme for quasi-stationary electromagnetic fields determination 3D problems
NASA Astrophysics Data System (ADS)
Chekmarev, D. T.; Kalinin, A. V.; Sadovsky, V. V.; Tiukhtina, A. A.
2016-11-01
The initial-boundary value problem for the quasi-stationary magnetic approximation of the Maxwell equations in inhomogeneous media is studied. The considered problem is reduced to the variational problem of determining the vector magnetic potential. The special gauge for vector magnetic and scalar electrical potentials is used. The well-posedness of the problems is established under general conditions on the coefficients and the applicability of the projection methods for these problems is validated. For the numerical solution of this problem provides to use the effective rare mesh FEM scheme for 3D problems. This scheme is well- proven in 3D elasticity and plasticity problems solving.
Xia, J; Wang, D; Samman, N; Yeung, R W; Tideman, H
2000-02-01
A scheme for texture mapping a 3D individualized color photo-realistic facial model from real color portraits and CT data is described. First, 3D CT images including both soft and hard tissues should be reconstructed from sequential CT slices, using a surface rendering technique. Facial features are extracted from 3D soft tissue. A generic mesh is individualized by correspondence matching and interpolation from those feature vertices. Three digitized color portraits with the "third" dimension from reconstructed soft tissue are blended and texture-mapped onto the 3D head model (mesh). A color simulated human head generated from frontal, right and left real color portraits can be viewed from an arbitrary angle in an inexpensive and user-friendly conventional personal computer. This scheme is the basic procedure in 3D computer-assisted simulation surgery.
Metal-mesh based transparent electrode on a 3-D curved surface by electrohydrodynamic jet printing
NASA Astrophysics Data System (ADS)
Seong, Baekhoon; Yoo, Hyunwoong; Dat Nguyen, Vu; Jang, Yonghee; Ryu, Changkook; Byun, Doyoung
2014-09-01
Invisible Ag mesh transparent electrodes (TEs), with a width of 7 μm, were prepared on a curved glass surface by electrohydrodynamic (EHD) jet printing. With a 100 μm pitch, the EHD jet printed the Ag mesh on the convex glass which had a sheet resistance of 1.49 Ω/□. The printing speed was 30 cm s-1 using Ag ink, which had a 10 000 cPs viscosity and a 70 wt% Ag nanoparticle concentration. We further showed the performance of a 3-D transparent heater using the Ag mesh transparent electrode. The EHD jet printed an invisible Ag grid transparent electrode with good electrical and optical properties with promising applications on printed optoelectronic devices.
Newe, Axel; Ganslandt, Thomas
2013-01-01
The usefulness of the 3D Portable Document Format (PDF) for clinical, educational, and research purposes has recently been shown. However, the lack of a simple tool for converting biomedical data into the model data in the necessary Universal 3D (U3D) file format is a drawback for the broad acceptance of this new technology. A new module for the image processing and rapid prototyping framework MeVisLab does not only provide a platform-independent possibility to create surface meshes out of biomedical/DICOM and other data and to export them into U3D--it also lets the user add meta data to these meshes to predefine colors and names that can be processed by a PDF authoring software while generating 3D PDF files. Furthermore, the source code of the respective module is available and well documented so that it can easily be modified for own purposes.
SHARP/PRONGHORN Interoperability: Mesh Generation
Avery Bingham; Javier Ortensi
2012-09-01
Progress toward collaboration between the SHARP and MOOSE computational frameworks has been demonstrated through sharing of mesh generation and ensuring mesh compatibility of both tools with MeshKit. MeshKit was used to build a three-dimensional, full-core very high temperature reactor (VHTR) reactor geometry with 120-degree symmetry, which was used to solve a neutron diffusion critical eigenvalue problem in PRONGHORN. PRONGHORN is an application of MOOSE that is capable of solving coupled neutron diffusion, heat conduction, and homogenized flow problems. The results were compared to a solution found on a 120-degree, reflected, three-dimensional VHTR mesh geometry generated by PRONGHORN. The ability to exchange compatible mesh geometries between the two codes is instrumental for future collaboration and interoperability. The results were found to be in good agreement between the two meshes, thus demonstrating the compatibility of the SHARP and MOOSE frameworks. This outcome makes future collaboration possible.
Chen, Luyun; Lenz, Florian; Alt, Céline D; Sohn, Christof; De Lancey, John O; Brocker, Kerstin A
2017-08-01
To demonstrate mesh magnetic resonance imaging (MRI) visibility in living women, the feasibility of reconstructing the full mesh course in 3D, and to document its spatial relationship to pelvic anatomical structures. This is a proof of concept study of three patients from a prospective multi-center trial evaluating women with anterior vaginal mesh repair using a MRI-visible Fe3O4 polypropylene implant for pelvic floor reconstruction. High-resolution sagittal T2-weighted (T2w) sequences, transverse T1-weighted (T1w) FLASH 2D, and transverse T1w FLASH 3D sequences were performed to evaluate Fe3O4 polypropylene mesh MRI visibility and overall post-surgical pelvic anatomy 3 months after reconstructive surgery. Full mesh course in addition to important pelvic structures were reconstructed using the 3D Slicer® software program based on T1w and T2w MRI. Three women with POP-Q grade III cystoceles were successfully treated with a partially absorbable MRI-visible anterior vaginal mesh with six fixation arms and showed no recurrent cystocele at the 3-month follow-up examination. The course of mesh in the pelvis was visible on MRI in all three women. The mesh body and arms could be reconstructed allowing visualization of the full course of the mesh in relationship to important pelvic structures such as the obturator or pudendal vessel nerve bundles in 3D. The use of MRI-visible Fe3O4 polypropylene meshes in combination with post-surgical 3D reconstruction of the mesh and adjacent structures is feasible suggesting that it might be a useful tool for evaluating mesh complications more precisely and a valuable interactive feedback tool for surgeons and mesh design engineers.
An efficient 3D traveltime calculation using coarse-grid mesh for shallow-depth source
NASA Astrophysics Data System (ADS)
Son, Woohyun; Pyun, Sukjoon; Lee, Ho-Young; Koo, Nam-Hyung; Shin, Changsoo
2016-10-01
3D Kirchhoff pre-stack depth migration requires an efficient algorithm to compute first-arrival traveltimes. In this paper, we exploited a wave-equation-based traveltime calculation algorithm, which is called the suppressed wave equation estimation of traveltime (SWEET), and the equivalent source distribution (ESD) algorithm. The motivation of using the SWEET algorithm is to solve the Laplace-domain wave equation using coarse grid spacing to calculate first-arrival traveltimes. However, if a real source is located at shallow-depth close to free surface, we cannot accurately calculate the wavefield using coarse grid spacing. So, we need an additional algorithm to correctly simulate the shallow source even for the coarse grid mesh. The ESD algorithm is a method to define a set of distributed nodal sources that approximate a point source at the inter-nodal location in a velocity model with large grid spacing. Thanks to the ESD algorithm, we can efficiently calculate the first-arrival traveltimes of waves emitted from shallow source point even when we solve the Laplace-domain wave equation using a coarse-grid mesh. The proposed algorithm is applied to the SEG/EAGE 3D salt model. From the result, we note that the combination of SWEET and ESD algorithms can be successfully used for the traveltime calculation under the condition of a shallow-depth source. We also confirmed that our algorithm using coarse-grid mesh requires less computational time than the conventional SWEET algorithm using relatively fine-grid mesh.
Chen, Shuo-Tsung; Chang, Cheng-Jen; Su, Wei-Chin; Chang, Lin-Wan; Chu, I-Hsuan; Lin, Muh-Shi
2015-01-01
Decompressive craniectomy (DC) is a treatment strategy used to reduce intracranial pressure in patients with traumatic brain injuries. However, this procedure has a number of shortcomings, such as excessive sinking of the skin flap, which can lead to cerebral compromise and negatively affect the appearance of the patient. The reconstruction of skull defects has been proposed as a means to overcome these disadvantages. Few previous studies have reported the reconstruction of frontal skull defects using titanium mesh. The aim of this study was to provide a comprehensive review of aesthetic and surgical outcomes associated with this procedure and to list the complications encountered during the repair of frontal skull defects using three-dimensional (3-D) titanium mesh. A retrospective review was conducted using records from seven adult patients (32-60 years of age) who received titanium mesh implants at a university hospital in Taiwan between January 2011 and June 2012. Aesthetic outcomes, the function of cranial nerves V and VII, and complications (hardware extrusions, meningitis, osteomyelitis, brain abscess, and pneumocephalus) were evaluated. An algorithm capable of accounting for bifrontal skull defects and median bone ridges was developed to improve computer-assisted design/manufacturing (CAD/CAM) of one-piece 3-D titanium mesh implants, thereby making it possible to repair bifrontal skull defects in a single operation. Following this procedure, aesthetic and functional outcomes were excellent and the implants in all patients appeared stable. However, extended healing times in two of the patients resulted in subclinical infections, which were resolved by administering antibiotics over a period of 2 weeks. No patients suffered trigeminal or facial dysfunction. Our findings support the use of 3-D titanium mesh in frontal skull reconstruction. Few complications were encountered, the contours of the forehead were faithfully rendered, and the cosmetic appearance of
Development of an Immersive Environment to Aid in Automatic Mesh Generation LDRD Final Report
Pavlakos, Constantine J.
1998-10-01
The purpose of this work was to explore the use of immersive technologies, such as those used in synthetic environments (commordy referred to as virtual realily, or VR), in enhancing the mesh- generation process for 3-dimensional (3D) engineering models. This work was motivated by the fact that automatic mesh generation systems are still imperfect - meshing algorithms, particularly in 3D, are sometimes unable to construct a mesh to completion, or they may produce anomalies or undesirable complexities in the resulting mesh. It is important that analysts and meshing code developers be able to study their meshes effectively in order to understand the topology and qualily of their meshes. We have implemented prototype capabilities that enable such exploration of meshes in a highly visual and intuitive manner. Since many applications are making use of increasingly large meshes, we have also investigated approaches to handle large meshes while maintaining interactive response. Ideally, it would also be possible to interact with the meshing process, allowing interactive feedback which corrects problems and/or somehow enables proper completion of the meshing process. We have implemented some functionality towards this end -- in doing so, we have explored software architectures that support such an interactive meshing process. This work has incorporated existing technologies developed at SandiaNational Laboratories, including the CUBIT mesh generation system, and the EIGEN/VR (previously known as MUSE) and FLIGHT systems, which allow applications to make use of immersive technologies and advanced human computer interfaces. 1
Three-dimensional (3D) printing of mouse primary hepatocytes to generate 3D hepatic structure.
Kim, Yohan; Kang, Kyojin; Jeong, Jaemin; Paik, Seung Sam; Kim, Ji Sook; Park, Su A; Kim, Wan Doo; Park, Jisun; Choi, Dongho
2017-02-01
The major problem in producing artificial livers is that primary hepatocytes cannot be cultured for many days. Recently, 3-dimensional (3D) printing technology draws attention and this technology regarded as a useful tool for current cell biology. By using the 3D bio-printing, these problems can be resolved. To generate 3D bio-printed structures (25 mm × 25 mm), cells-alginate constructs were fabricated by 3D bio-printing system. Mouse primary hepatocytes were isolated from the livers of 6-8 weeks old mice by a 2-step collagenase method. Samples of 4 × 10(7) hepatocytes with 80%-90% viability were printed with 3% alginate solution, and cultured with well-defined culture medium for primary hepatocytes. To confirm functional ability of hepatocytes cultured on 3D alginate scaffold, we conducted quantitative real-time polymerase chain reaction and immunofluorescence with hepatic marker genes. Isolated primary hepatocytes were printed with alginate. The 3D printed hepatocytes remained alive for 14 days. Gene expression levels of Albumin, HNF-4α and Foxa3 were gradually increased in the 3D structures. Immunofluorescence analysis showed that the primary hepatocytes produced hepatic-specific proteins over the same period of time. Our research indicates that 3D bio-printing technique can be used for long-term culture of primary hepatocytes. It can therefore be used for drug screening and as a potential method of producing artificial livers.
Three-dimensional (3D) printing of mouse primary hepatocytes to generate 3D hepatic structure
Kim, Yohan; Kang, Kyojin; Jeong, Jaemin; Paik, Seung Sam; Kim, Ji Sook; Park, Su A; Kim, Wan Doo; Park, Jisun
2017-01-01
Purpose The major problem in producing artificial livers is that primary hepatocytes cannot be cultured for many days. Recently, 3-dimensional (3D) printing technology draws attention and this technology regarded as a useful tool for current cell biology. By using the 3D bio-printing, these problems can be resolved. Methods To generate 3D bio-printed structures (25 mm × 25 mm), cells-alginate constructs were fabricated by 3D bio-printing system. Mouse primary hepatocytes were isolated from the livers of 6–8 weeks old mice by a 2-step collagenase method. Samples of 4 × 107 hepatocytes with 80%–90% viability were printed with 3% alginate solution, and cultured with well-defined culture medium for primary hepatocytes. To confirm functional ability of hepatocytes cultured on 3D alginate scaffold, we conducted quantitative real-time polymerase chain reaction and immunofluorescence with hepatic marker genes. Results Isolated primary hepatocytes were printed with alginate. The 3D printed hepatocytes remained alive for 14 days. Gene expression levels of Albumin, HNF-4α and Foxa3 were gradually increased in the 3D structures. Immunofluorescence analysis showed that the primary hepatocytes produced hepatic-specific proteins over the same period of time. Conclusion Our research indicates that 3D bio-printing technique can be used for long-term culture of primary hepatocytes. It can therefore be used for drug screening and as a potential method of producing artificial livers. PMID:28203553
3D model generation using an airborne swarm
NASA Astrophysics Data System (ADS)
Clark, R. A.; Punzo, G.; Dobie, G.; MacLeod, C. N.; Summan, R.; Pierce, G.; Macdonald, M.; Bolton, G.
2015-03-01
Using an artificial kinematic field to provide co-ordination between multiple inspection UAVs, the authors herein demonstrate full 3D modelling capability based on a photogrammetric system. The operation of the system is demonstrated by generating a full 3D surface model of an intermediate level nuclear waste storage drum. Such drums require periodic inspection to ensure that drum distortion or corrosion is carefully monitored. Performing this inspection with multiple airborne platforms enables rapid inspection of structures that are inaccessible to on-surface remote vehicles and are in human-hazardous environments. A three-dimensional surface-meshed model of the target can then be constructed in post-processing through photogrammetry analysis of the visual inspection data. The inspection environment uses a tracking system to precisely monitor the position of each aerial vehicle within the enclosure. The vehicles used are commercially available Parrot AR. Drone quadcopters, controlled through a computer interface connected over an IEEE 802.11n (WiFi) network, implementing a distributed controller for each vehicle. This enables the autonomous and distributed elements of the control scheme to be retained, while alleviating the vehicles of the control algorithm's computational load. The control scheme relies on a kinematic field defined with the target at its centre. This field defines the trajectory for all the drones in the volume relative to the central target, enabling the drones to circle the target at a set radius while avoiding drone collisions. This function enables complete coverage along the height of the object, which is assured by transitioning to another inspection band only after completing circumferential coverage. Using a swarm of vehicles, the time until complete coverage can be significantly reduced.
3D model generation using an airborne swarm
Clark, R. A.; Punzo, G.; Macdonald, M.; Dobie, G.; MacLeod, C. N.; Summan, R.; Pierce, G.; Bolton, G.
2015-03-31
Using an artificial kinematic field to provide co-ordination between multiple inspection UAVs, the authors herein demonstrate full 3D modelling capability based on a photogrammetric system. The operation of the system is demonstrated by generating a full 3D surface model of an intermediate level nuclear waste storage drum. Such drums require periodic inspection to ensure that drum distortion or corrosion is carefully monitored. Performing this inspection with multiple airborne platforms enables rapid inspection of structures that are inaccessible to on-surface remote vehicles and are in human-hazardous environments. A three-dimensional surface-meshed model of the target can then be constructed in post-processing through photogrammetry analysis of the visual inspection data. The inspection environment uses a tracking system to precisely monitor the position of each aerial vehicle within the enclosure. The vehicles used are commercially available Parrot AR. Drone quadcopters, controlled through a computer interface connected over an IEEE 802.11n (WiFi) network, implementing a distributed controller for each vehicle. This enables the autonomous and distributed elements of the control scheme to be retained, while alleviating the vehicles of the control algorithm’s computational load. The control scheme relies on a kinematic field defined with the target at its centre. This field defines the trajectory for all the drones in the volume relative to the central target, enabling the drones to circle the target at a set radius while avoiding drone collisions. This function enables complete coverage along the height of the object, which is assured by transitioning to another inspection band only after completing circumferential coverage. Using a swarm of vehicles, the time until complete coverage can be significantly reduced.
A method for generating 3D thermal models with decoupled acquisition.
Krefer, Andriy Guilherme; Lie, Maiko Min Ian; Borba, Gustavo Benvenutti; Gamba, Humberto Remigio; Lavarda, Marcos Dinís; Abreu de Souza, Mauren
2017-11-01
Both thermal imaging and 3D scanning offer convenient advantages for medical applications, namely, being contactless, non-invasive and fast. Consequently, many approaches have been proposed to combine both sensing modalities in order to acquire 3D thermal models. The predominant approach is to affix a 3D scanner and a thermal camera in the same support and calibrate them together. While this approach allows straightforward projection of thermal images over the 3D mesh, it requires their simultaneous acquisition. In this work, a method for generation of 3D thermal models that allows combination of separately acquired 3D mesh and thermal images is presented. Among the advantages of this decoupled acquisition are increased modularity of acquisition procedures and reuse of legacy equipment and data. The proposed method is based on the projection of thermal images over a 3D mesh. Unlike previous methods, it is considered that the 3D mesh and the thermal images are acquired separately, so camera pose estimation is required to determine the correct spatial positioning from which to project the images. This is done using Structure from Motion, which requires a series of interest points correspondences between the images, for which the SIFT method was used. As thermal images of human skin are predominantly homogeneous, an intensity transformation is proposed to increase the efficacy of interest point detection and make the approach feasible. Before projection, the adequate alignment of the 3D mesh in space is determined using Particle Swarm Optimization. For validation of the method, the design and implementation of a test object is presented. It can be used to validate other methods and can be reproduced with common printed circuit board manufacturing processes. The proposed approach is accurate, with an average displacement error of 1.41 mm (s = 0.74 mm) with the validation test object and 4.58 mm (s = 2.12 mm) with human subjects. The proposed method is able to
Large-Scale Parallel Unstructured Mesh Computations for 3D High-Lift Analysis
NASA Technical Reports Server (NTRS)
Mavriplis, D. J.; Pirzadeh, S.
1999-01-01
A complete "geometry to drag-polar" analysis capability for three-dimensional high-lift configurations is described. The approach is based on the use of unstructured meshes in order to enable rapid turnaround for complicated geometries which arise in high-lift con gurations. Special attention is devoted to creating a capability for enabling analyses on highly resolved grids. Unstructured meshes of several million vertices are initially generated on a work-station, and subsequently refined on a supercomputer. The flow is solved on these refined meshes on large parallel computers using an unstructured agglomeration multigrid algorithm. Good prediction of lift and drag throughout the range of incidences is demonstrated on a transport take-off configuration using up to 24.7 million grid points. The feasibility of using this approach in a production environment on existing parallel machines is demonstrated, as well as the scalability of the solver on machines using up to 1450 processors.
Large-scale Parallel Unstructured Mesh Computations for 3D High-lift Analysis
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.; Pirzadeh, S.
1999-01-01
A complete "geometry to drag-polar" analysis capability for the three-dimensional high-lift configurations is described. The approach is based on the use of unstructured meshes in order to enable rapid turnaround for complicated geometries that arise in high-lift configurations. Special attention is devoted to creating a capability for enabling analyses on highly resolved grids. Unstructured meshes of several million vertices are initially generated on a work-station, and subsequently refined on a supercomputer. The flow is solved on these refined meshes on large parallel computers using an unstructured agglomeration multigrid algorithm. Good prediction of lift and drag throughout the range of incidences is demonstrated on a transport take-off configuration using up to 24.7 million grid points. The feasibility of using this approach in a production environment on existing parallel machines is demonstrated, as well as the scalability of the solver on machines using up to 1450 processors.
Large-Scale Parallel Unstructured Mesh Computations for 3D High-Lift Analysis
NASA Technical Reports Server (NTRS)
Mavriplis, D. J.; Pirzadeh, S.
1999-01-01
A complete "geometry to drag-polar" analysis capability for three-dimensional high-lift configurations is described. The approach is based on the use of unstructured meshes in order to enable rapid turnaround for complicated geometries which arise in high-lift configurations. Special attention is devoted to creating a capability for enabling analyses on highly resolved grids. Unstructured meshes of several million vertices are initially generated on a work-station, and subsequently refined on a supercomputer. The flow is solved on these refined meshes on large parallel computers using an unstructured agglomeration multigrid algorithm. Good prediction of lift and drag throughout the range of incidences is demonstrated on a transport take-off configuration using up to 24.7 million grid points. The feasibility of using this approach in a production environment on existing parallel machines is demonstrated, as well as the scalability of the solver on machines using up to 1450 processors.
Robust and Blind 3D Mesh Watermarking in Spatial Domain Based on Faces Categorization and Sorting
NASA Astrophysics Data System (ADS)
Molaei, Amir Masoud; Ebrahimnezhad, Hossein; Sedaaghi, Mohammad Hossein
2016-06-01
In this paper, a 3D watermarking algorithm in spatial domain is presented with blind detection. In the proposed method, a negligible visual distortion is observed in host model. Initially, a preprocessing is applied on the 3D model to make it robust against geometric transformation attacks. Then, a number of triangle faces are determined as mark triangles using a novel systematic approach in which faces are categorized and sorted robustly. In order to enhance the capability of information retrieval by attacks, block watermarks are encoded using Reed-Solomon block error-correcting code before embedding into the mark triangles. Next, the encoded watermarks are embedded in spherical coordinates. The proposed method is robust against additive noise, mesh smoothing and quantization attacks. Also, it is stout next to geometric transformation, vertices and faces reordering attacks. Moreover, the proposed algorithm is designed so that it is robust against the cropping attack. Simulation results confirm that the watermarked models confront very low distortion if the control parameters are selected properly. Comparison with other methods demonstrates that the proposed method has good performance against the mesh smoothing attacks.
A 3D moving mesh Finite Element Method for two-phase flows
NASA Astrophysics Data System (ADS)
Anjos, G. R.; Borhani, N.; Mangiavacchi, N.; Thome, J. R.
2014-08-01
A 3D ALE Finite Element Method is developed to study two-phase flow phenomena using a new discretization method to compute the surface tension forces. The computational method is based on the Arbitrary Lagrangian-Eulerian formulation (ALE) and the Finite Element Method (FEM), creating a two-phase method with an improved model for the liquid-gas interface. An adaptive mesh update procedure is also proposed for effective management of the mesh to remove, add and repair elements, since the computational mesh nodes move according to the flow. The ALE description explicitly defines the two-phase interface position by a set of interconnected nodes which ensures a sharp representation of the boundary, including the role of the surface tension. The proposed methodology for computing the curvature leads to accurate results with moderate programming effort and computational cost. Static and dynamic tests have been carried out to validate the method and the results have compared well to analytical solutions and experimental results found in the literature, demonstrating that the new proposed methodology provides good accuracy to describe the interfacial forces and bubble dynamics. This paper focuses on the description of the proposed methodology, with particular emphasis on the discretization of the surface tension force, the new remeshing technique, and the validation results. Additionally, a microchannel simulation in complex geometry is presented for two elongated bubbles.
Structured mesh generation with smoothness controls
USDA-ARS?s Scientific Manuscript database
In geometrically complex domains, the RL (Ryskin and Leal) orthogonal mesh generation system may cause mesh distortion and overlapping problems when using the “weak constraint” method with specified boundary point distribution for all boundaries. To resolve these problems, an improved RL system with...
Robust Detection of Round Shaped Pits Lying on 3D Meshes: Application to Impact Crater Recognition
NASA Astrophysics Data System (ADS)
Schmidt, Martin-Pierre; Muscato, Jennifer; Viseur, Sophie; Jorda, Laurent; Bouley, Sylvain; Mari, Jean-Luc
2015-04-01
Most celestial bodies display impacts of collisions with asteroids and meteoroids. These traces are called craters. The possibility of observing and identifying these craters and their characteristics (radius, depth and morphology) is the only method available to measure the age of different units at the surface of the body, which in turn allows to constrain its conditions of formation. Interplanetary space probes always carry at least one imaging instrument on board. The visible images of the target are used to reconstruct high-resolution 3D models of its surface as a cloud of points in the case of multi-image dense stereo, or as a triangular mesh in the case of stereo and shape-from-shading. The goal of this work is to develop a methodology to automatically detect the craters lying on these 3D models. The robust extraction of feature areas on surface objects embedded in 3D, like circular pits, is a challenging problem. Classical approaches generally rely on image processing and template matching on a 2D flat projection of the 3D object (i.e.: a high-resolution photograph). In this work, we propose a full-3D method that mainly relies on curvature analysis. Mean and Gaussian curvatures are estimated on the surface. They are used to label vertices that belong to concave parts corresponding to specific pits on the surface. The surface is thus transformed into binary map distinguishing potential crater features to other types of features. Centers are located in the targeted surface regions, corresponding to potential crater features. Concentric rings are then built around the found centers. They consist in circular closed lines exclusively composed of edges of the initial mesh. The first built ring represents the nearest vertex neighborhood of the found center. The ring is then optimally expanded using a circularity constrain and the curvature values of the ring vertices. This method has been tested on a 3D model of the asteroid Lutetia observed by the ROSETTA (ESA
NASA Astrophysics Data System (ADS)
Gonizzi Barsanti, S.; Guidi, G.
2017-02-01
Conservation of Cultural Heritage is a key issue and structural changes and damages can influence the mechanical behaviour of artefacts and buildings. The use of Finite Elements Methods (FEM) for mechanical analysis is largely used in modelling stress behaviour. The typical workflow involves the use of CAD 3D models made by Non-Uniform Rational B-splines (NURBS) surfaces, representing the ideal shape of the object to be simulated. Nowadays, 3D documentation of CH has been widely developed through reality-based approaches, but the models are not suitable for a direct use in FEA: the mesh has in fact to be converted to volumetric, and the density has to be reduced since the computational complexity of a FEA grows exponentially with the number of nodes. The focus of this paper is to present a new method aiming at generate the most accurate 3D representation of a real artefact from highly accurate 3D digital models derived from reality-based techniques, maintaining the accuracy of the high-resolution polygonal models in the solid ones. The approach proposed is based on a wise use of retopology procedures and a transformation of this model to a mathematical one made by NURBS surfaces suitable for being processed by volumetric meshers typically embedded in standard FEM packages. The strong simplification with little loss of consistency possible with the retopology step is used for maintaining as much coherence as possible between the original acquired mesh and the simplified model, creating in the meantime a topology that is more favourable for the automatic NURBS conversion.
Joint sparse learning for 3-D facial expression generation.
Song, Mingli; Tao, Dacheng; Sun, Shengpeng; Chen, Chun; Bu, Jiajun
2013-08-01
3-D facial expression generation, including synthesis and retargeting, has received intensive attentions in recent years, because it is important to produce realistic 3-D faces with specific expressions in modern film production and computer games. In this paper, we present joint sparse learning (JSL) to learn mapping functions and their respective inverses to model the relationship between the high-dimensional 3-D faces (of different expressions and identities) and their corresponding low-dimensional representations. Based on JSL, we can effectively and efficiently generate various expressions of a 3-D face by either synthesizing or retargeting. Furthermore, JSL is able to restore 3-D faces with holes by learning a mapping function between incomplete and intact data. Experimental results on a wide range of 3-D faces demonstrate the effectiveness of the proposed approach by comparing with representative ones in terms of quality, time cost, and robustness.
Detection of impact crater in 3D mesh by extraction of feature lines
NASA Astrophysics Data System (ADS)
Jorda, L.; Mari, J.-L.; Viseur, S.; Bouley, S.
2013-09-01
Impact craters are observed at the surface of most solar system bodies: terrestrial planets, satellites and asteroids. The measurement of their size-frequency distribution (SFD) is the only method available to estimate the age of the observed geological units, assuming a rate and velocity distributions of impactors and a crater scaling law. The age of the geological units is fundamental to establish a chronology of events explaining the global evolution of the surface. In addition, the detailed characterization of the crater properties (depth-to-diameter ratio and radial profile) yields a better understanding of the geological processes which altered the observed surfaces. Crater detection is usually performed manually directly from the acquired images. However, this method can become prohibitive when dealing with small craters extracted from very large data sets. A large number of solar system objects is being mapped at a very high spatial resolution by space probes since a few decades, emphasizing the need for new automatic methods of crater detection. Powerful computers are now available to produce and analyze huge 3D models of the surface in the form of 3D meshes containing tens to hundreds of billions of facets. This motivates the development of a new family of automatic crater detection algorithms (CDAs). The automatic CDAs developed so far were mainly based on morphological analyses and pattern recognition techniques on 2D images (e.g., Bandeira et al., 2012). Since a few years, new CDAs based on 3D models are being developed (see, e.g., Salamuniccar and Loncaric, 2010). Our objective is to develop and test against existing methods an automatic CDA using a new approach based on the discrete differential properties of 3D meshes. The method (Kudelski et al., 2010, 2011a,b) produces the feature lines (the crest and the ravine lines) lying on the surface. It is based on a double step algorithm: first, the regions of interest are flagged according to curvature
Characterization of impact craters in 3D meshes using a feature lines approach
NASA Astrophysics Data System (ADS)
Jorda, L.; Mari, J.; Viseur, S.; Bouley, S.
2013-12-01
Impact craters are observed at the surface of most solar system bodies: terrestrial planets, satellites and asteroids.The measurement of their size-frequency distribution (SFD) is the only method available to estimate the age of the observed geological units, assuming a rate and velocity distributions of impactors and a crater scaling law. The age of the geological units is fundamental to establish a chronology of events explaining the global evolution of the surface. In addition, the detailed characterization of the crater properties (depth-to-diameter ratio and radial profile) yields a better understanding of the geological processes which altered the observed surfaces. Crater detection is usually performed manually directly from the acquired images. However, this method can become prohibitive when dealing with small craters extracted from very large data sets. A large number of solar system objects is being mapped at a very high spatial resolution by space probes since a few decades, emphasizing the need for new automatic methods of crater detection. Powerful computers are now available to produce and analyze huge 3D models of the surface in the form of 3D meshes containing tens to hundreds of billions of facets. This motivates the development of a new family of automatic crater detection algorithms (CDAs). The automatic CDAs developed so far were mainly based on morphological analyses and pattern recognition techniques on 2D images. Since a few years, new CDAs based on 3D models are being developed. Our objective is to develop and test against existing methods an automatic CDA using a new approach based on the discrete differential properties of 3D meshes. The method produces the feature lines (the crest and the ravine lines) lying on the surface. It is based on a double step algorithm: first, the regions of interest are flagged according to curvature properties, and then an original skeletonization approach is applied to extract the feature lines. This new
Zouhar, Alexander; Baloch, Sajjad; Tsin, Yanghai; Fang, Tong; Fuchs, Siegfried
2010-01-01
We address the problem of 3-D Mesh segmentation for categories of objects with known part structure. Part labels are derived from a semantic interpretation of non-overlapping subsurfaces. Our approach models the label distribution using a Conditional Random Field (CRF) that imposes constraints on the relative spatial arrangement of neighboring labels, thereby ensuring semantic consistency. To this end, each label variable is associated with a rich shape descriptor that is intrinsic to the surface. Randomized decision trees and cross validation are employed for learning the model, which is eventually applied using graph cuts. The method is flexible enough for segmenting even geometrically less structured regions and is robust to local and global shape variations.
Dynamic Implicit 3D Adaptive Mesh Refinement for Non-Equilibrium Radiation Diffusion
Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael
2014-01-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multiphysics systems: implicit time integration for efficient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent linear solver convergence.
A new high-order finite volume method for 3D elastic wave simulation on unstructured meshes
NASA Astrophysics Data System (ADS)
Zhang, Wensheng; Zhuang, Yuan; Zhang, Lina
2017-07-01
In this paper, we proposed a new efficient high-order finite volume method for 3D elastic wave simulation on unstructured tetrahedral meshes. With the relative coarse tetrahedral meshes, we make subdivision in each tetrahedron to generate a stencil for the high-order polynomial reconstruction. The subdivision algorithm guarantees the number of subelements is greater than the degrees of freedom of a complete polynomial. We perform the reconstruction on this stencil by using cell-averaged quantities based on the hierarchical orthonormal basis functions. Unlike the traditional high-order finite volume method, our new method has a very local property like DG and can be written as an inner-split computational scheme which is beneficial to reducing computational amount. Moreover, the stencil in our method is easy to generate for all tetrahedrons especially in the three-dimensional case. The resulting reconstruction matrix is invertible and remains unchanged for all tetrahedrons and thus it can be pre-computed and stored before time evolution. These special advantages facilitate the parallelization and high-order computations. We show convergence results obtained with the proposed method up to fifth order accuracy in space. The high-order accuracy in time is obtained by the Runge-Kutta method. Comparisons between numerical and analytic solutions show the proposed method can provide accurate wavefield information. Numerical simulation for a realistic model with complex topography demonstrates the effectiveness and potential applications of our method. Though the method is proposed based on the 3D elastic wave equation, it can be extended to other linear hyperbolic system.
Generating animated sequences from 3D whole-body scans
NASA Astrophysics Data System (ADS)
Pargas, Roy P.; Chhatriwala, Murtuza; Mulfinger, Daniel; Deshmukh, Pushkar; Vadhiyar, Sathish
1999-03-01
3D images of human subjects are, today, easily obtained using 3D wholebody scanners. 3D human images can provide static information about the physical characteristics of a person, information valuable to professionals such as clothing designers, anthropometrists, medical doctors, physical therapists, athletic trainers, and sculptors. Can 3D human images can be used to provide e more than static physical information. This research described in this paper attempts to answer the question by explaining a way that animated sequences may be generated from a single 3D scan. The process stars by subdividing the human image into segments and mapping the segments to those of a human model defined in a human-motion simulation package. The simulation software provides information used to display movement of the human image. Snapshots of the movement are captured and assembled to create an animated sequence. All of the postures and motion of the human images come from a single 3D scan. This paper describes the process involved in animating human figures from static 3D wholebody scans, presents an example of a generated animated sequence, and discusses possible applications of this approach.
NASA Astrophysics Data System (ADS)
Christoff, Nicole; Jorda, Laurent; Viseur, Sophie; Bouley, Sylvain; Manolova, Agata; Mari, Jean-Luc
2017-04-01
One of the challenges of Planetary Science is to estimate as accurately as possible the age of the geological units that crop out on the different space objects in the Solar system. This dating relies on the counting of the impact craters that cover the given outcrop surface. Using this technique, a chronology of the geological events can be determined and their formation and evolution processes can be understood. Over the last decade, several missions to asteroids and planets, such as Dawn to Vesta and Ceres, Messenger to Mercury, Mars Orbiter and Mars Express, produced a huge amount of images, from which equally huge DEMs have been generated. Planned missions, such as BepiColombo, will produce an even larger set of images. This rapidly growing amount of visible images and DEMs makes it more and more fastidious to manually identify craters. Acquisition data will become bigger and this will then require more accurate planetary surface analysis. Because of the importance of the problem, many Crater Detection Algorithm (CDA) were developed and applied onto either image data (2D) or DEM (2D1/5), and rarely onto full 3D data such as 3D topographic meshes. We propose a new approach, based on the detection of crater rim, which form a characteristic round shape. The proposed approach contains two main steps: 1) each vertex is labelled with the values of the mean curvature and minimal curvatures; 2) this curvature map is injected into a Neural Network (NN) to automatically process the region of interest. As a NN approach, it requires a training set of manually detected craters to estimate the optimal weights of the NN. Once trained, the NN can be applied onto the regions of interest for automatically extracting all the craters. As a result, it was observed that detecting forms using a two-dimensional map based on the computation of discrete differential estimators on the 3D mesh is more efficient than using a simple elevation map. This approach significantly reduces the
NASA Astrophysics Data System (ADS)
Bajc, Iztok; Hecht, Frédéric; Žumer, Slobodan
2016-09-01
This paper presents a 3D mesh adaptivity strategy on unstructured tetrahedral meshes by a posteriori error estimates based on metrics derived from the Hessian of a solution. The study is made on the case of a nonlinear finite element minimization scheme for the Landau-de Gennes free energy functional of nematic liquid crystals. Newton's iteration for tensor fields is employed with steepest descent method possibly stepping in. Aspects relating the driving of mesh adaptivity within the nonlinear scheme are considered. The algorithmic performance is found to depend on at least two factors: when to trigger each single mesh adaptation, and the precision of the correlated remeshing. Each factor is represented by a parameter, with its values possibly varying for every new mesh adaptation. We empirically show that the time of the overall algorithm convergence can vary considerably when different sequences of parameters are used, thus posing a question about optimality. The extensive testings and debugging done within this work on the simulation of systems of nematic colloids substantially contributed to the upgrade of an open source finite element-oriented programming language to its 3D meshing possibilities, as also to an outer 3D remeshing module.
The Feasibility of 3d Point Cloud Generation from Smartphones
NASA Astrophysics Data System (ADS)
Alsubaie, N.; El-Sheimy, N.
2016-06-01
This paper proposes a new technique for increasing the accuracy of direct geo-referenced image-based 3D point cloud generated from low-cost sensors in smartphones. The smartphone's motion sensors are used to directly acquire the Exterior Orientation Parameters (EOPs) of the captured images. These EOPs, along with the Interior Orientation Parameters (IOPs) of the camera/ phone, are used to reconstruct the image-based 3D point cloud. However, because smartphone motion sensors suffer from poor GPS accuracy, accumulated drift and high signal noise, inaccurate 3D mapping solutions often result. Therefore, horizontal and vertical linear features, visible in each image, are extracted and used as constraints in the bundle adjustment procedure. These constraints correct the relative position and orientation of the 3D mapping solution. Once the enhanced EOPs are estimated, the semi-global matching algorithm (SGM) is used to generate the image-based dense 3D point cloud. Statistical analysis and assessment are implemented herein, in order to demonstrate the feasibility of 3D point cloud generation from the consumer-grade sensors in smartphones.
A 3D stand generator for central Appalachian hardwood forests
Jingxin Wang; Yaoxiang Li; Gary W. Miller
2002-01-01
A 3-dimensional (3D) stand generator was developed for central Appalachian hardwood forests. It was designed for a harvesting simulator to examine the interactions of stand, harvest, and machine. The Component Object Model (COM) was used to design and implement the program. Input to the generator includes species composition, stand density, and spatial pattern. Output...
Generating 3D building models from architectural drawings: a survey.
Yin, Xuetao; Wonka, Peter; Razdan, Anshuman
2009-01-01
Automatically generating 3D building models from 2D architectural drawings has many useful applications in the architecture engineering and construction community. This survey of model generation from paper and CAD-based architectural drawings covers the common pipeline and compares various algorithms for each step of the process.
A multistage mesh generator for solving the average-passage equation system
NASA Technical Reports Server (NTRS)
Mulac, Richard A.
1988-01-01
One means of numerically simulating the 3-D flow field within a multistage turbomachine is through the solution of the average-passage equation system. One requirement of a current algorithm used to solve this system of equations has been the ability to generate multiple blade row meshes which satisfy specific geometrical constraints. In addition to meeting this criterion, one desires a mesh generation code which requires minimal user input, utilizes variable mesh control parameters, generates diagnostics helpful to the user, and possesses the capability to handle widely varying geometries. A mesh generation code with these features was written and has been used in solving the inviscid form of the average-passing equation system for both ducted and unducted multiple blade row geometries. This paper serves as a user reference guide, with a description of the mesh generation algorithm, a sample input file, and examples of typical meshes generated.
Fast generation of virtual X-ray images for reconstruction of 3D anatomy.
Ehlke, Moritz; Ramm, Heiko; Lamecker, Hans; Hege, Hans-Christian; Zachow, Stefan
2013-12-01
We propose a novel GPU-based approach to render virtual X-ray projections of deformable tetrahedral meshes. These meshes represent the shape and the internal density distribution of a particular anatomical structure and are derived from statistical shape and intensity models (SSIMs). We apply our method to improve the geometric reconstruction of 3D anatomy (e.g. pelvic bone) from 2D X-ray images. For that purpose, shape and density of a tetrahedral mesh are varied and virtual X-ray projections are generated within an optimization process until the similarity between the computed virtual X-ray and the respective anatomy depicted in a given clinical X-ray is maximized. The OpenGL implementation presented in this work deforms and projects tetrahedral meshes of high resolution (200.000+ tetrahedra) at interactive rates. It generates virtual X-rays that accurately depict the density distribution of an anatomy of interest. Compared to existing methods that accumulate X-ray attenuation in deformable meshes, our novel approach significantly boosts the deformation/projection performance. The proposed projection algorithm scales better with respect to mesh resolution and complexity of the density distribution, and the combined deformation and projection on the GPU scales better with respect to the number of deformation parameters. The gain in performance allows for a larger number of cycles in the optimization process. Consequently, it reduces the risk of being stuck in a local optimum. We believe that our approach will improve treatments in orthopedics, where 3D anatomical information is essential.
Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion
NASA Astrophysics Data System (ADS)
Philip, B.; Wang, Z.; Berrill, M. A.; Birke, M.; Pernice, M.
2014-04-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion
B. Philip; Z. Wang; M.A. Berrill; M. Birke; M. Pernice
2014-04-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton–Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
Scalable and Adaptive Streaming of 3D Mesh to Heterogeneous Devices
NASA Astrophysics Data System (ADS)
Abderrahim, Zeineb; Bouhlel, Mohamed Salim
2016-12-01
This article comprises a presentation of a web platform for the diffusion and visualization of 3D compressed data on the web. Indeed, the major goal of this work resides in the proposal of the transfer adaptation of the three-dimensional data to resources (network bandwidth, the type of visualization terminals, display resolution, user's preferences...). Also, it is an attempt to provide an effective consultation adapted to the user's request (preferences, levels of the requested detail, etc.). Such a platform can adapt the levels of detail to the change in the bandwidth and the rendering time when loading the mesh at the client level. In addition, the levels of detail are adapted to the distance between the object and the camera. These features are able to minimize the latency time and to make the real time interaction possible. The experiences as well as the comparison with the existing solutions show auspicious results in terms of latency, scalability and the quality of the experience offered to the users.
2D nearly orthogonal mesh generation
NASA Astrophysics Data System (ADS)
Zhang, Yaoxin; Jia, Yafei; Wang, Sam S. Y.
2004-11-01
The Ryskin and Leal (RL) system is the most widely used mesh generation system for the orthogonal mapping. However, when this system is used in domains with complex geometry, particularly in those with sharp corners and strong curvatures, serious distortion or overlapping of mesh lines may occur and an acceptable solution may not be possible. In the present study, two methods are proposed to generate nearly orthogonal meshes with the smoothness control. In the first method, the original RL system is modified by introducing smoothness control functions, which are formulated through the blending of the conformal mapping and the orthogonal mapping; while in the second method, the RL system is modified by introducing the contribution factors. A hybrid system of both methods is also developed. The proposed methods are illustrated by several test examples. Applications of these methods in a natural river channel are demonstrated. It is shown that the modified RL systems are capable of producing meshes with an adequate balance between the orthogonality and the smoothness for complex computational domains without mesh distortions and overlapping.
3D Model Generation From the Engineering Drawing
NASA Astrophysics Data System (ADS)
Vaský, Jozef; Eliáš, Michal; Bezák, Pavol; Červeňanská, Zuzana; Izakovič, Ladislav
2010-01-01
The contribution deals with the transformation of engineering drawings in a paper form into a 3D computer representation. A 3D computer model can be further processed in CAD/CAM system, it can be modified, archived, and a technical drawing can be then generated from it as well. The transformation process from paper form to the data one is a complex and difficult one, particularly owing to the different types of drawings, forms of displayed objects and encountered errors and deviations from technical standards. The algorithm for 3D model generating from an orthogonal vector input representing a simplified technical drawing of the rotational part is described in this contribution. The algorithm was experimentally implemented as ObjectARX application in the AutoCAD system and the test sample as the representation of the rotational part was used for verificaton.
Kondo, Kosuke; Harada, Naoyuki; Masuda, Hiroyuki; Sugo, Nobuo; Terazono, Sayaka; Okonogi, Shinichi; Sakaeyama, Yuki; Fuchinoue, Yutaka; Ando, Syunpei; Fukushima, Daisuke; Nomoto, Jun; Nemoto, Masaaki
2016-06-01
Deep regions are not visible in three-dimensional (3D) printed rapid prototyping (RP) models prepared from opaque materials, which is not the case with translucent images. The objectives of this study were to develop an RP model in which a skull base tumor was simulated using mesh, and to investigate its usefulness for surgical simulations by evaluating the visibility of its deep regions. A 3D printer that employs binder jetting and is mainly used to prepare plaster models was used. RP models containing a solid tumor, no tumor, and a mesh tumor were prepared based on computed tomography, magnetic resonance imaging, and angiographic data for four cases of petroclival tumor. Twelve neurosurgeons graded the three types of RP model into the following four categories: 'clearly visible,' 'visible,' 'difficult to see,' and 'invisible,' based on the visibility of the internal carotid artery, basilar artery, and brain stem through a craniotomy performed via the combined transpetrosal approach. In addition, the 3D positional relationships between these structures and the tumor were assessed. The internal carotid artery, basilar artery, and brain stem and the positional relationships of these structures with the tumor were significantly more visible in the RP models with mesh tumors than in the RP models with solid or no tumors. The deep regions of PR models containing mesh skull base tumors were easy to visualize. This 3D printing-based method might be applicable to various surgical simulations.
NASA Astrophysics Data System (ADS)
Gansen, A.; Hachemi, M. El; Belouettar, S.; Hassan, O.; Morgan, K.
2016-09-01
The standard Yee algorithm is widely used in computational electromagnetics because of its simplicity and divergence free nature. A generalization of the classical Yee scheme to 3D unstructured meshes is adopted, based on the use of a Delaunay primal mesh and its high quality Voronoi dual. This allows the problem of accuracy losses, which are normally associated with the use of the standard Yee scheme and a staircased representation of curved material interfaces, to be circumvented. The 3D dual mesh leapfrog-scheme which is presented has the ability to model both electric and magnetic anisotropic lossy materials. This approach enables the modelling of problems, of current practical interest, involving structured composites and metamaterials.
3D measurement system based on computer-generated gratings
NASA Astrophysics Data System (ADS)
Zhu, Yongjian; Pan, Weiqing; Luo, Yanliang
2010-08-01
A new kind of 3D measurement system has been developed to achieve the 3D profile of complex object. The principle of measurement system is based on the triangular measurement of digital fringe projection, and the fringes are fully generated from computer. Thus the computer-generated four fringes form the data source of phase-shifting 3D profilometry. The hardware of system includes the computer, video camera, projector, image grabber, and VGA board with two ports (one port links to the screen, another to the projector). The software of system consists of grating projection module, image grabbing module, phase reconstructing module and 3D display module. A software-based synchronizing method between grating projection and image capture is proposed. As for the nonlinear error of captured fringes, a compensating method is introduced based on the pixel-to-pixel gray correction. At the same time, a least square phase unwrapping is used to solve the problem of phase reconstruction by using the combination of Log Modulation Amplitude and Phase Derivative Variance (LMAPDV) as weight. The system adopts an algorithm from Matlab Tool Box for camera calibration. The 3D measurement system has an accuracy of 0.05mm. The execution time of system is 3~5s for one-time measurement.
Analysis of 3D multi-layer microfluidic gradient generator.
Ha, Jang Ho; Kim, Tae Hyeon; Lee, Jong Min; Ahrberg, Christian D; Chung, Bong Geun
2017-01-01
We developed a three-dimensional (3D) simple multi-layer microfluidic gradient generator to create molecular gradients on the centimeter scale with a wide range of flow rates. To create the concentration gradients, a main channel (MC) was orthogonally intersected with vertical side microchannel (SC) in a 3D multi-layer microfluidic device. Through sequential dilution from the SC, a spatial gradient was generated in the MC. Two theoretical models were created to assist in the design of the 3D multi-layer microfluidic gradient generator and to compare its performance against a two-dimensional equivalent. A first mass balance model was used to predict the steady-state concentrations reached, while a second computational fluid dynamic model was employed to predict spatial development of the gradient by considering convective as well as diffusive mass transport. Furthermore, the theoretical simulations were verified through experiments to create molecular gradients in a 3D multi-layer microfluidic gradient generator. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Ma, Junli; Ma, Limin; Wang, Zhifa; Zhu, Xiongjie; Wang, Weijian
2017-07-01
Precise bony reduction and reconstruction of optimal contour in treating comminuted mandibular fractures is very difficult using traditional techniques and devices. The aim of this report is to introduce our experiences in using virtual surgery and three-dimensional (3D) printing technique in treating this clinical challenge. A 26-year-old man presented with severe trauma in the maxillofacial area due to fall from height. Computed tomography images revealed middle face fractures and comminuted mandibular fracture including bilateral condyles. The computed tomography data was used to construct the 3D cranio-maxillofacial models; then the displaced bone fragments were virtually reduced. On the basis of the finalized model, a customized titanium mesh tray was designed and fabricated using selective laser melting technology. During the surgery, a submandibular approach was adopted to repair the mandibular fracture. The reduction and fixation were performed according to preoperative plan, the bone defects in the mental area were reconstructed with iliac bone graft. The 3D-printed mesh tray served as an intraoperative template and carrier of bone graft. The healing process was uneventful, and the patient was satisfied with the mandible contour. Virtual surgical planning combined with 3D printing technology enables surgeon to visualize the reduction process preoperatively and guide intraoperative reduction, making the reduction less time consuming and more precise. 3D-printed titanium mesh tray can provide more satisfactory esthetic outcomes in treating complex comminuted mandibular fractures.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.
1999-05-01
Koide et al have investigated the dynamics of an accretion disk initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code on a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics. 3-D RMHD simulations wil be also performed to investigate the dynamics of a jet with a helical mangetic field in it.
Multiple footprint stereo algorithms for 3D display content generation
NASA Astrophysics Data System (ADS)
Boughorbel, Faysal
2007-02-01
This research focuses on the conversion of stereoscopic video material into an image + depth format which is suitable for rendering on the multiview auto-stereoscopic displays of Philips. The recent interest shown in the movie industry for 3D significantly increased the availability of stereo material. In this context the conversion from stereo to the input formats of 3D displays becomes an important task. In this paper we present a stereo algorithm that uses multiple footprints generating several depth candidates for each image pixel. We characterize the various matching windows and we devise a robust strategy for extracting high quality estimates from the resulting depth candidates. The proposed algorithm is based on a surface filtering method that employs simultaneously the available depth estimates in a small local neighborhood while ensuring correct depth discontinuities by the inclusion of image constraints. The resulting highquality image-aligned depth maps proved an excellent match with our 3D displays.
Generation of 3D Collagen Gels with Controlled Diverse Architectures.
Doyle, Andrew D
2016-09-01
Rat tail collagen solutions have been used as polymerizable in vitro three dimensional (3D) extracellular matrix (ECM) gels for single and collective cell migration assays as well as spheroid formation. Factors such as ECM concentration, pH, ionic concentration, and temperature can alter collagen polymerization and ECM architecture. This unit describes how to generate 3D collagen gels that have distinct architectures ranging from a highly reticular meshwork of short thin fibrils with small pores to a loose matrix consisting of stiff, parallel-bundled long fibrils by changing collagen polymerization temperature. This permits analysis of 3D cell migration in different ECM architectures found in vivo while maintaining a similar ECM concentration. Also included are collagen labeling techniques helpful for ECM visualization during live fluorescence imaging. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.
V-Man Generation for 3-D Real Time Animation. Chapter 5
NASA Technical Reports Server (NTRS)
Nebel, Jean-Christophe; Sibiryakov, Alexander; Ju, Xiangyang
2007-01-01
The V-Man project has developed an intuitive authoring and intelligent system to create, animate, control and interact in real-time with a new generation of 3D virtual characters: The V-Men. It combines several innovative algorithms coming from Virtual Reality, Physical Simulation, Computer Vision, Robotics and Artificial Intelligence. Given a high-level task like "walk to that spot" or "get that object", a V-Man generates the complete animation required to accomplish the task. V-Men synthesise motion at runtime according to their environment, their task and their physical parameters, drawing upon its unique set of skills manufactured during the character creation. The key to the system is the automated creation of realistic V-Men, not requiring the expertise of an animator. It is based on real human data captured by 3D static and dynamic body scanners, which is then processed to generate firstly animatable body meshes, secondly 3D garments and finally skinned body meshes.
Constrained CVT Meshes and a Comparison of Triangular Mesh Generators
Nguyen, Hoa; Burkardt, John; Gunzburger, Max; Ju, Lili; Saka, Yuki
2009-01-01
Mesh generation in regions in Euclidean space is a central task in computational science, and especially for commonly used numerical methods for the solution of partial differential equations, e.g., finite element and finite volume methods. We focus on the uniform Delaunay triangulation of planar regions and, in particular, on how one selects the positions of the vertices of the triangulation. We discuss a recently developed method, based on the centroidal Voronoi tessellation (CVT) concept, for effecting such triangulations and present two algorithms, including one new one, for CVT-based grid generation. We also compare several methods, including CVT-based methods, for triangulating planar domains. To this end, we define several quantitative measures of the quality of uniform grids. We then generate triangulations of several planar regions, including some having complexities that are representative of what one may encounter in practice. We subject the resulting grids to visual and quantitative comparisons and conclude that all the methods considered produce high-quality uniform grids and that the CVT-based grids are at least as good as any of the others.
Tool-assisted mesh generation based on a tissue-growth model.
Smirnov, A V
2003-07-01
An heuristic mesh generation technique is proposed that is based on the model of forced particle motion, an edgewise cell-splitting algorithm and a moving tool concept. The method differs from conventional mesh generators in that it uses outward growth of the mesh, in contrast to the inward growth used in traditional meshing techniques. The method does not require prior meshing and patching of two-dimensional (2D) boundary surfaces. Instead, it uses a pre-defined skeleton of one-dimensional segments, or an arbitrary tool motion in three-dimensional (3D) space. In this respect, the technique can be considered as a 3D extension of a 2D drawing tool and can find applications in virtual reality systems. The method also guarantees the smoothness of the outer boundary of the mesh at each step of mesh generation, which is not the case with traditional propagating-front methods. The approach is based on the model of tissue growth and is suitable for meshing complex networks of bifurcating branches commonly found in biological structures: blood vessels, lungs, neural networks, plants etc. The generated meshes were used in solving unsteady flow and particle transport problems in lungs.
An Adaptive Mesh Algorithm: Mesh Structure and Generation
Scannapieco, Anthony J.
2016-06-21
The purpose of Adaptive Mesh Refinement is to minimize spatial errors over the computational space not to minimize the number of computational elements. The additional result of the technique is that it may reduce the number of computational elements needed to retain a given level of spatial accuracy. Adaptive mesh refinement is a computational technique used to dynamically select, over a region of space, a set of computational elements designed to minimize spatial error in the computational model of a physical process. The fundamental idea is to increase the mesh resolution in regions where the physical variables are represented by a broad spectrum of modes in k-space, hence increasing the effective global spectral coverage of those physical variables. In addition, the selection of the spatially distributed elements is done dynamically by cyclically adjusting the mesh to follow the spectral evolution of the system. Over the years three types of AMR schemes have evolved; block, patch and locally refined AMR. In block and patch AMR logical blocks of various grid sizes are overlaid to span the physical space of interest, whereas in locally refined AMR no logical blocks are employed but locally nested mesh levels are used to span the physical space. The distinction between block and patch AMR is that in block AMR the original blocks refine and coarsen entirely in time, whereas in patch AMR the patches change location and zone size with time. The type of AMR described herein is a locally refi ned AMR. In the algorithm described, at any point in physical space only one zone exists at whatever level of mesh that is appropriate for that physical location. The dynamic creation of a locally refi ned computational mesh is made practical by a judicious selection of mesh rules. With these rules the mesh is evolved via a mesh potential designed to concentrate the nest mesh in regions where the physics is modally dense, and coarsen zones in regions where the physics is modally
NASA Astrophysics Data System (ADS)
Beguet, Florian; Bali, Sarah; Christoff, Nicole; Jorda, Laurent; Viseur, Sophie; Bouley, Sylvain; Manolova, Agata; Mari, Jean-Luc
2016-04-01
Impact craters is a typical feature observed at the surface of most bodies in the solar system: terrestrial planets, their satellites, asteroids and even possibly cometary nuclei exhibit impact craters. Their spatial density yields the estimation of the age of the surface, a key parameter required for subsequent geological studies. With the development of interplanetary missions, a large number of solar system objects have been mapped at a high spatial resolution, emphasizing the need for new automatic methods of crater detection and counting. In this work, we present such a method using a new approach based on the analysis of reconstructed 3D meshes instead of 2D images. The robust extraction of feature areas on surface objects embedded in 3D, like circular shapes, is a challenging problem. Classical approaches generally rely on image processing and template matching on a 2D flat projection of the 3D object (for instance a high-resolution picture). In this paper, we propose a full 3D method that mainly relies on curvature analysis. Mean and Gaussian curvatures are estimated on the surface. They are used to label vertices that belong to concave parts corresponding to specific pits on the surface. Centers are located in the targeted surface regions, corresponding to potential crater features. Then "best fit circles" are extracted, based on the rims of the circular shapes. They consist in closed lines exclusively composed of edges of the initial mesh. This approach has been applied to the detection of craters on the asteroid Vesta. Keywords: geometric modeling, 3D meshes, shape recognition, mesh processing, discrete curvatures, asteroids, crater detection, geology, geomorphology.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.
1999-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.
2001-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.
2000-12-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.
3-D General Relativistic MHD Simulations of Generating Jets
NASA Astrophysics Data System (ADS)
Nishikawa, Ken-Ichi; Koide, Shinji; Shibata, Kazunari; Kudoh, Takashiro; Sol, Helene; Hughes, John
2002-04-01
We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J × B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.
DISCO: A 3D Moving-mesh Magnetohydrodynamics Code Designed for the Study of Astrophysical Disks
NASA Astrophysics Data System (ADS)
Duffell, Paul C.
2016-09-01
This work presents the publicly available moving-mesh magnetohydrodynamics (MHD) code DISCO. DISCO is efficient and accurate at evolving orbital fluid motion in two and three dimensions, especially at high Mach numbers. DISCO employs a moving-mesh approach utilizing a dynamic cylindrical mesh that can shear azimuthally to follow the orbital motion of the gas. The moving mesh removes diffusive advection errors and allows for longer time-steps than a static grid. MHD is implemented in DISCO using an HLLD Riemann solver and a novel constrained transport (CT) scheme that is compatible with the mesh motion. DISCO is tested against a wide variety of problems, which are designed to test its stability, accuracy, and scalability. In addition, several MHD tests are performed which demonstrate the accuracy and stability of the new CT approach, including two tests of the magneto-rotational instability, one testing the linear growth rate and the other following the instability into the fully turbulent regime.
NASA Astrophysics Data System (ADS)
Danilov, A. A.; Salamatova, V. Yu; Vassilevski, Yu V.
2012-12-01
Here, a workflow for high-resolution efficient numerical modeling of bioimpedance measurements is suggested that includes 3D image segmentation, adaptive mesh generation, finite-element discretization, and the analysis of simulation results. Using the adaptive unstructured tetrahedral meshes enables to decrease significantly a number of mesh elements while keeping model accuracy. The numerical results illustrate current, potential, and sensitivity field distributions for a conventional Kubicek-like scheme of bioimpedance measurements using segmented geometric model of human torso based on Visible Human Project data. The whole body VHP man computational mesh is constructed that contains 574 thousand vertices and 3.3 million tetrahedrons.
Nune, K C; Kumar, A; Misra, R D K; Li, S J; Hao, Y L; Yang, R
2017-02-01
We elucidate here the osteoblasts functions and cellular activity in 3D printed interconnected porous architecture of functionally gradient Ti-6Al-4V alloy mesh structures in terms of cell proliferation and growth, distribution of cell nuclei, synthesis of proteins (actin, vinculin, and fibronectin), and calcium deposition. Cell culture studies with pre-osteoblasts indicated that the interconnected porous architecture of functionally gradient mesh arrays was conducive to osteoblast functions. However, there were statistically significant differences in the cellular response depending on the pore size in the functionally gradient structure. The interconnected porous architecture contributed to the distribution of cells from the large pore size (G1) to the small pore size (G3), with consequent synthesis of extracellular matrix and calcium precipitation. The gradient mesh structure significantly impacted cell adhesion and influenced the proliferation stage, such that there was high distribution of cells on struts of the gradient mesh structure. Actin and vinculin showed a significant difference in normalized expression level of protein per cell, which was absent in the case of fibronectin. Osteoblasts present on mesh struts formed a confluent sheet, bridging the pores through numerous cytoplasmic extensions. The gradient mesh structure fabricated by electron beam melting was explored to obtain fundamental insights on cellular activity with respect to osteoblast functions. Copyright © 2016 Elsevier B.V. All rights reserved.
Cartesian-cell based grid generation and adaptive mesh refinement
NASA Technical Reports Server (NTRS)
Coirier, William J.; Powell, Kenneth G.
1993-01-01
Viewgraphs on Cartesian-cell based grid generation and adaptive mesh refinement are presented. Topics covered include: grid generation; cell cutting; data structures; flow solver formulation; adaptive mesh refinement; and viscous flow.
Köhler, G; Hofmann, A; Lechner, M; Mayer, F; Wundsam, H; Emmanuel, K; Fortelny, R H
2016-02-01
In patients with terminal ostomies, parastomal hernias (PSHs) occur on a frequent basis. They are commonly associated with various degrees of complaints and occasionally lead to life-threatening complications. Various strategies and measures have been tested and evaluated, but to date there is a lack of published evidence with regard to the best surgical technique for the prevention of PSH development. We conducted a retrospective analysis of prospectively collected data of eighty patients, who underwent elective permanent ostomy formation between 2009 and 2014 by means of prophylactic implantation of a three-dimensional (3D) funnel mesh in intraperitoneal onlay (IPOM) position. PSH developed in three patients (3.75%). No mesh-related complications were encountered and none of the implants had to be removed. Ostomy-related complications had to be noted in seven (8.75%) cases. No manifestation of ostomy prolapse occurred. Follow-up time was a median 21 (range 3-47) months. The prophylactical implantation of a specially shaped, 3D mesh implant in IPOM technique during initial formation of a terminal enterostomy is safe, highly efficient and comparatively easy to perform. As opposed to what can be achieved with flat or keyhole meshes, the inner boundary areas of the ostomy itself can be well covered and protected from the surging viscera with the 3D implants. At the same time, the vertical, tunnel-shaped part of the mesh provides sufficient protection from an ostomy prolapse. Further studies will be needed to compare the efficacy of various known approaches to PSH prevention.
Simplified 3D protocol capable of generating early cortical neuroepithelium
Holmes, Dwayne B.
2017-01-01
ABSTRACT Here, we report a 3D cerebellar differentiation protocol with quick startup method, defined medium and no special materials or handling requirements. Three fibroblast growth factors (FGF2, 4 and 8) were used for cerebellar patterning and smoothened agonist (SAG) for granule cell development. After 35 days, differentiation products exhibited similar structures and neuronal markers reported in prior ‘organoid’ and ‘spheroid’ protocols. This included cells positive for KIRREL2 (a marker of early cerebellar neuroepithelium) and ZIC1 (a marker for granule cells). Follow-up tests indicated that addition of FGFs, if helpful, was not required to generate observed structures and cell types. This suggests that intrinsic production of patterning factors by aggregates themselves may be adequate for region-specific 3D modeling. This protocol may be used as a quick, easy and cost-efficient method for 3D culture, whether to research development of the early cerebellar neuroepithelium, a base to generate mature cortical structures, or to optimize minimal-factor protocols for other brain regions. PMID:28167491
Generation and use of human 3D-CAD models
NASA Astrophysics Data System (ADS)
Grotepass, Juergen; Speyer, Hartmut; Kaiser, Ralf
2002-05-01
Individualized Products are one of the ten mega trends of the 21st Century with human modeling as the key issue for tomorrow's design and product development. The use of human modeling software for computer based ergonomic simulations within the production process increases quality while reducing costs by 30- 50 percent and shortening production time. This presentation focuses on the use of human 3D-CAD models for both, the ergonomic design of working environments and made to measure garment production. Today, the entire production chain can be designed, individualized models generated and analyzed in 3D computer environments. Anthropometric design for ergonomics is matched to human needs, thus preserving health. Ergonomic simulation includes topics as human vision, reachability, kinematics, force and comfort analysis and international design capabilities. In German more than 17 billions of Mark are moved to other industries, because clothes do not fit. Individual clothing tailored to the customer's preference means surplus value, pleasure and perfect fit. The body scanning technology is the key to generation and use of human 3D-CAD models for both, the ergonomic design of working environments and made to measure garment production.
Recent Enhancements To The FUN3D Flow Solver For Moving-Mesh Applications
NASA Technical Reports Server (NTRS)
Biedron, Robert T,; Thomas, James L.
2009-01-01
An unsteady Reynolds-averaged Navier-Stokes solver for unstructured grids has been extended to handle general mesh movement involving rigid, deforming, and overset meshes. Mesh deformation is achieved through analogy to elastic media by solving the linear elasticity equations. A general method for specifying the motion of moving bodies within the mesh has been implemented that allows for inherited motion through parent-child relationships, enabling simulations involving multiple moving bodies. Several example calculations are shown to illustrate the range of potential applications. For problems in which an isolated body is rotating with a fixed rate, a noninertial reference-frame formulation is available. An example calculation for a tilt-wing rotor is used to demonstrate that the time-dependent moving grid and noninertial formulations produce the same results in the limit of zero time-step size.
Reddy, A.V.; Kothe, D.B.; Lam, K.L.
1997-06-01
The Los Alamos National Laboratory (LANL) is currently developing a new casting simulation tool (known as Telluride) that employs robust, high-resolution finite volume algorithms for incompressible fluid flow, volume tracking of interfaces, and solidification physics on three-dimensional (3-D) unstructured meshes. Their finite volume algorithms are based on colocated cell-centered schemes that are formally second order in time and space. The flow algorithm is a 3-D extension of recent work on projection method solutions of the Navier-Stokes (NS) equations. Their volume tracking algorithm can accurately track topologically complex interfaces by approximating the interface geometry as piecewise planar. Coupled to their fluid flow algorithm is a comprehensive binary alloy solidification model that incorporates macroscopic descriptions of heat transfer, solute redistribution, and melt convection as well as a microscopic description of segregation. The finite volume algorithms, which are efficient, parallel, and robust, can yield high-fidelity solutions on a variety of meshes, ranging from those that are structured orthogonal to fully unstructured (finite element). The authors discuss key computer science issues that have enabled them to efficiently parallelize their unstructured mesh algorithms on both distributed and shared memory computing platforms. These include their functionally object-oriented use of Fortran 90 and new parallel libraries for gather/scatter functions (PGSLib) and solutions of linear systems of equations (JTpack90). Examples of their current capabilities are illustrated with simulations of mold filling and solidification of complex 3-D components currently being poured in LANL foundries.
Vertical-Axis Wind Turbine Mesh Generator
2014-01-24
VAWTGen is a mesh generator for creating a finite element beam mesh of arbitrary vertical-axis wind turbines (VAWT). The software accepts input files specifying tower and blade structural and aerodynamic descriptions and constructs a VAWT using a minimal set of inputs. VAWTs with an arbitrary number of blades can be constructed with or without a central tower. Strut connections between the tower and blades can be specified in an arbitrary manner. The software also facilitates specifying arbitrary joints between structural components and concentrated structural tenns (mass and stiffness). The output files which describe the VAWT configuration are intended to be used with the Offshore Wind ENergy Simulation (OWENS) Toolkit software for structural dynamics analysis of VAWTs. Furthermore, VAWTGen is useful for visualizing output from the OWENS analysis software.
Structured mesh generation with smoothness controls
NASA Astrophysics Data System (ADS)
Zhang, Yaoxin; Jia, Yafei; Wang, Sam S. Y.
2006-08-01
In geometrically complex domains, the Ryskin and Leal (RL) orthogonal mesh generation system may cause mesh distortion and overlapping problems when using the weak constraint method with specified boundary point distribution for all boundaries. To resolve these problems, an improved RL system with automatic smoothness control is proposed. In this improved RL system, the automatic smoothness control mechanism is based on five types of smoothness conditions and includes the self-adjustment mechanism and the auto-evaluation mechanism for an empirical parameter. The proposed system is illustrated using several test examples. Several applications to natural domains are also demonstrated. It is shown that the improved RL system is capable of resolving the above problems at little cost of orthogonality.
Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems
NASA Technical Reports Server (NTRS)
Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John
2010-01-01
Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.
CUBIT mesh generation environment. Volume 1: Users manual
Blacker, T.D.; Bohnhoff, W.J.; Edwards, T.L.
1994-05-01
The CUBIT mesh generation environment is a two- and three-dimensional finite element mesh generation tool which is being developed to pursue the goal of robust and unattended mesh generation--effectively automating the generation of quadrilateral and hexahedral elements. It is a solid-modeler based preprocessor that meshes volume and surface solid models for finite element analysis. A combination of techniques including paving, mapping, sweeping, and various other algorithms being developed are available for discretizing the geometry into a finite element mesh. CUBIT also features boundary layer meshing specifically designed for fluid flow problems. Boundary conditions can be applied to the mesh through the geometry and appropriate files for analysis generated. CUBIT is specifically designed to reduce the time required to create all-quadrilateral and all-hexahedral meshes. This manual is designed to serve as a reference and guide to creating finite element models in the CUBIT environment.
Note: 3D printed spheroid for uniform magnetic field generation
NASA Astrophysics Data System (ADS)
Öztürk, Y.; Aktaş, B.
2016-10-01
This article is focused on a novel and practical production method for a uniform magnetic field generator. The method involves building of a surface coil template using a desktop 3D printer and winding of a conducting wire onto the structure using surface grooves as a guide. Groove pattern was based on the parametric spheroidal helical coil formula. The coil was driven by a current source and the magnetic field inside was measured using a Hall probe placed into the holes on the printed structure. The measurements are found to be in good agreement with our finite element analysis results and indicate a fairly uniform field inside.
An overset mesh approach for 3D mixed element high-order discretizations
NASA Astrophysics Data System (ADS)
Brazell, Michael J.; Sitaraman, Jayanarayanan; Mavriplis, Dimitri J.
2016-10-01
A parallel high-order Discontinuous Galerkin (DG) method is used to solve the compressible Navier-Stokes equations in an overset mesh framework. The DG solver has many capabilities including: hp-adaption, curved cells, support for hybrid, mixed-element meshes, and moving meshes. Combining these capabilities with overset grids allows the DG solver to be used in problems with bodies in relative motion and in a near-body off-body solver strategy. The overset implementation is constructed to preserve the design accuracy of the baseline DG discretization. Multiple simulations are carried out to validate the accuracy and performance of the overset DG solver. These simulations demonstrate the capability of the high-order DG solver to handle complex geometry and large scale parallel simulations in an overset framework.
A density driven mesh generator guided by a neural network
Lowther, D.A.; Dyck, D.N. )
1993-03-01
A neural network guided mesh generator is described. The mesh generator used density information provided by the neural network to determine the size and placement of elements. This system is coupled with an adaptive meshing and solving process and is shown to have major computational benefits compared with adaptation alone.
Cubit Mesh Generation Toolkit V11.1
HANKS, BYRON; KERR, ROBERT; KNUPP, PATRICK; MAEZ, JONATHAN; WHITE, DAVID; MITCHELL, SCOTT; OWEN, STEVEN; SHEPHERD, JASON; TAUTGES, TIMOTHY; MELANDER, DARRYL; BLACKER, TEDDY; BORDEN, MICHAEL; BREWER, MICHAEL; CLARK, BRETT; FORTIER, LESLIE; KALLAHER, JENNA; PEBAY, PHILIPPE; STATEN, MATTHEW; VINEYARD, CRAIG; GROVER, BENJAMIN; BENZLEY, STEVEN; SIMPSON, CLINTON; NIELSON, ERIC; KOPP, JOEL; STORM, STEVE; NUGENT, MARK; WALTON, KIRK; BORDEN, MIKE; ERNST, CORY; FOWLER, JOHN; KRAFTCHECL, JASON; STEPHNSON, MIKE; YEOU, RAMMAGAY; MERKLEY, KARL; METERS, RAY; DEWET, MARK; RICHARDS, SARA; PENDLEY, KEVIN; MORRIS, RANDY; RICHARDSON, MARK; VYAS, VED; SHOWMAN, SAM; HAYS, ALEX; TIDWELL, BOYD; MILLAR, ALEX
2009-03-25
CUBIT prepares models to be used in computer-based simulation of real-world events. CUBIT is a full-featured software toolkit for robust generation of two- and three-dimensional finite element meshes (grids) and geometry preparation. Its main goal is to reduce the time to generate meshes, particularly large hex meshes of complicated, interlocking assemblies.
On Adaptive Mesh Generation in Two-Dimensions
D'Azevedo, E.
1999-10-11
This work considers the effectiveness of using anisotropic coordinate transformation in adaptive mesh generation. The anisotropic coordinate transformation is derived by interpreting the Hessian matrix of the data function as a metric tensor that measures the local approximation error. The Hessian matrix contains information about the local curvature of the surface and gives guidance in the aspect ratio and orientation for mesh generation. Since theoretically, an asymptotically optimally efficient mesh can be produced by transforming a regular mesh of optimal shape elements, it would be interesting to compare this approach with existing techniques in solution adaptive meshes. PLTMG , a general elliptic solver, is used to generate solution adapted triangular meshes for comparison. The solver has the capability of performing a posteriori error estimates in performing longest edge refinement, vertex unrefinement and mesh smoothing. Numerical experiments on three simple problems suggest the methodology employed in PLTMG is effective in generating near optimally efficient meshes.
Update on Development of Mesh Generation Algorithms in MeshKit
Jain, Rajeev; Vanderzee, Evan; Mahadevan, Vijay
2015-09-30
MeshKit uses a graph-based design for coding all its meshing algorithms, which includes the Reactor Geometry (and mesh) Generation (RGG) algorithms. This report highlights the developmental updates of all the algorithms, results and future work. Parallel versions of algorithms, documentation and performance results are reported. RGG GUI design was updated to incorporate new features requested by the users; boundary layer generation and parallel RGG support were added to the GUI. Key contributions to the release, upgrade and maintenance of other SIGMA1 libraries (CGM and MOAB) were made. Several fundamental meshing algorithms for creating a robust parallel meshing pipeline in MeshKit are under development. Results and current status of automated, open-source and high quality nuclear reactor assembly mesh generation algorithms such as trimesher, quadmesher, interval matching and multi-sweeper are reported.
Drag Prediction for the NASA CRM Wing-Body-Tail Using CFL3D and OVERFLOW on an Overset Mesh
NASA Technical Reports Server (NTRS)
Sclafani, Anthony J.; DeHaan, Mark A.; Vassberg, John C.; Rumsey, Christopher L.; Pulliam, Thomas H.
2010-01-01
In response to the fourth AIAA CFD Drag Prediction Workshop (DPW-IV), the NASA Common Research Model (CRM) wing-body and wing-body-tail configurations are analyzed using the Reynolds-averaged Navier-Stokes (RANS) flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built for DPW-IV. Grid Family 1 (GF1) consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 (GF2) is an extension of the first and includes a superfine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on GF1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on GF1 and to obtain results for GF2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes.
Adaptive optimal quantization for 3D mesh representation in the spherical coordinate system
NASA Astrophysics Data System (ADS)
Ahn, Jeong-Hwan; Ho, Yo-Sung
1998-12-01
In recent days, applications using 3D models are increasing. Since the 3D model contains a huge amount of information, compression of the 3D model data is necessary for efficient storage or transmission. In this paper, we propose an adaptive encoding scheme to compress the geometry information of the 3D model. Using the Levinson-Durbin algorithm, the encoder first predicts vertex positions along a vertex spanning tree. After each prediction error is normalized, the prediction error vector of each vertex point is represented in the spherical coordinate system (r,(theta) ,(phi) ). Each r is then quantizes by an optimal uniform quantizer. A pair of each ((theta) ,(phi) ) is also successively encoded by partitioning the surface of the sphere according to the quantized value of r. The proposed scheme demonstrates improved coding efficiency by exploiting the statistical properties of r and ((theta) ,(phi) ).
NASA Astrophysics Data System (ADS)
Sun, Lu; Yeh, Gour-Tsyh; Zhao, Guoqun
2017-05-01
This paper developed an automatic mesh generator used for simulating real-world problems of hydrological cycles, fluid flow, salinity and thermal transport, sediment and water quality transport, etc. The 2-D overland area was discretized with quadrilaterals based on conformal mapping technique. A position-percent interpolation equation was established to determine nodal vertical-coordinates and match boundaries. For 3-D simulations of subsurface zones, an additional mesh generation method was proposed to create quadrilaterals for filling the empty regions along river reaches and around junctions with storage, ponds or lakes. In order to deal with special storage region with an odd number of boundary nodes, an additional triangle was inserted. Five topological optimization templates were proposed to improve the quality of degenerated elements. This paper proposed the basic algorithms to generate quadrilateral-prism meshes through stretching the quadrilateral mesh along vertical directions based on material domains. Aiming at four types of fractures, corresponding extraction methods were presented to preserve geometric features. In order to accommodate the need for overland and subsurface simulations, 1-D/2-D/3-D correspondence was established between rivers, junctions, ponds, lakes, control structures and finite element meshes. Finally, several realistic hydrologic and geologic examples for meshing multi-domain areas were provided to demonstrate the accuracy and effectiveness of the mesh generator developed in this paper.
NASA Astrophysics Data System (ADS)
Wendling, A.; Daniel, J. L.; Hivet, G.; Vidal-Sallé, E.; Boisse, P.
2015-12-01
Numerical simulation is a powerful tool to predict the mechanical behavior and the feasibility of composite parts. Among the available numerical approaches, as far as woven reinforced composites are concerned, 3D finite element simulation at the mesoscopic scale leads to a good compromise between realism and complexity. At this scale, the fibrous reinforcement is modeled by an interlacement of yarns assumed to be homogeneous that have to be accurately represented. Among the numerous issues induced by these simulations, the first one consists in providing a representative meshed geometrical model of the unit cell at the mesoscopic scale. The second one consists in enabling a fast data input in the finite element software (contacts definition, boundary conditions, elements reorientation, etc.) so as to obtain results within reasonable time. Based on parameterized 3D CAD modeling tool of unit-cells of dry fabrics already developed, this paper presents an efficient strategy which permits an automated meshing of the models with 3D hexahedral elements and to accelerate of several orders of magnitude the simulation data input. Finally, the overall modeling strategy is illustrated by examples of finite element simulation of the mechanical behavior of fabrics.
Mitton, D; Landry, C; Véron, S; Skalli, W; Lavaste, F; De Guise, J A
2000-03-01
Standard 3D reconstruction of bones using stereoradiography is limited by the number of anatomical landmarks visible in more than one projection. The proposed technique enables the 3D reconstruction of additional landmarks that can be identified in only one of the radiographs. The principle of this method is the deformation of an elastic object that respects stereocorresponding and non-stereocorresponding observations available in different projections. This technique is based on the principle that any non-stereocorresponding point belongs to a line joining the X-ray source and the projection of the point in one view. The aim is to determine the 3D position of these points on their line of projection when submitted to geometrical and topological constraints. This technique is used to obtain the 3D geometry of 18 cadaveric upper cervical vertebrae. The reconstructed geometry obtained is compared with direct measurements using a magnetic digitiser. The order of precision determined with the point-to-surface distance between the reconstruction obtained with that technique and reference measurements is about 1 mm, depending on the vertebrae studied. Comparison results indicate that the obtained reconstruction is close to the actual vertebral geometry. This method can therefore be proposed to obtain the 3D geometry of vertebrae.
The generation of hexahedral meshes for assembly geometries: A survey
TAUTGES,TIMOTHY J.
2000-02-14
The finite element method is being used today to model component assemblies in a wide variety of application areas, including structural mechanics, fluid simulations, and others. Generating hexahedral meshes for these assemblies usually requires the use of geometry decomposition, with different meshing algorithms applied to different regions. While the primary motivation for this approach remains the lack of an automatic, reliable all-hexahedral meshing algorithm, requirements in mesh quality and mesh configuration for typical analyses are also factors. For these reasons, this approach is also sometimes required when producing other types of unstructured meshes. This paper will review progress to date in automating many parts of the hex meshing process, which has halved the time to produce all-hex meshes for large assemblies. Particular issues which have been exposed due to this progress will also be discussed, along with their applicability to the general unstructured meshing problem.
A 3-D adaptive mesh refinement algorithm for multimaterial gas dynamics
Puckett, E.G. ); Saltzman, J.S. )
1991-08-12
Adaptive Mesh Refinement (AMR) in conjunction with high order upwind finite difference methods has been used effectively on a variety of problems. In this paper we discuss an implementation of an AMR finite difference method that solves the equations of gas dynamics with two material species in three dimensions. An equation for the evolution of volume fractions augments the gas dynamics system. The material interface is preserved and tracked from the volume fractions using a piecewise linear reconstruction technique. 14 refs., 4 figs.
Mesh generation by conformal and quasiconformal mappings
NASA Technical Reports Server (NTRS)
Mastin, C. W.; Thompson, J. F.
1981-01-01
It is pointed out that many recent advances in the finite-difference solution of elliptic equations have been limited to regions whose boundary contours coincide with coordinate lines of the Cartesian coordinate system. The reason for this is related to the fact that in the case of an arbitrary curvilinear coordinate system the original equation becomes much more complex. However, there is no added complexity if an orthogonal coordinate system is generated from a conformal mapping. In the present investigation, a finite difference method developed for the construction of conformal mappings has been generalized to construct quasi-conformal mappings. It is expected that the use of more sophisticated numerical algorithms could lead to improvements in both speed and accuracy. Quasi-conformal mappings have applications not only in the solution of elliptic equations but also in other areas such as orthogonal mesh generation on surfaces and the solution of certain fluid flow problems.
3D High Resolution Mesh Deformation Based on Multi Library Wavelet Neural Network Architecture
NASA Astrophysics Data System (ADS)
Dhibi, Naziha; Elkefi, Akram; Bellil, Wajdi; Amar, Chokri Ben
2016-12-01
This paper deals with the features of a novel technique for large Laplacian boundary deformations using estimated rotations. The proposed method is based on a Multi Library Wavelet Neural Network structure founded on several mother wavelet families (MLWNN). The objective is to align features of mesh and minimize distortion with a fixed feature that minimizes the sum of the distances between all corresponding vertices. New mesh deformation method worked in the domain of Region of Interest (ROI). Our approach computes deformed ROI, updates and optimizes it to align features of mesh based on MLWNN and spherical parameterization configuration. This structure has the advantage of constructing the network by several mother wavelets to solve high dimensions problem using the best wavelet mother that models the signal better. The simulation test achieved the robustness and speed considerations when developing deformation methodologies. The Mean-Square Error and the ratio of deformation are low compared to other works from the state of the art. Our approach minimizes distortions with fixed features to have a well reconstructed object.
Atlas-Based Automatic Generation of Subject-Specific Finite Element Tongue Meshes.
Bijar, Ahmad; Rohan, Pierre-Yves; Perrier, Pascal; Payan, Yohan
2016-01-01
Generation of subject-specific 3D finite element (FE) models requires the processing of numerous medical images in order to precisely extract geometrical information about subject-specific anatomy. This processing remains extremely challenging. To overcome this difficulty, we present an automatic atlas-based method that generates subject-specific FE meshes via a 3D registration guided by Magnetic Resonance images. The method extracts a 3D transformation by registering the atlas' volume image to the subject's one, and establishes a one-to-one correspondence between the two volumes. The 3D transformation field deforms the atlas' mesh to generate the subject-specific FE mesh. To preserve the quality of the subject-specific mesh, a diffeomorphic non-rigid registration based on B-spline free-form deformations is used, which guarantees a non-folding and one-to-one transformation. Two evaluations of the method are provided. First, a publicly available CT-database is used to assess the capability to accurately capture the complexity of each subject-specific Lung's geometry. Second, FE tongue meshes are generated for two healthy volunteers and two patients suffering from tongue cancer using MR images. It is shown that the method generates an appropriate representation of the subject-specific geometry while preserving the quality of the FE meshes for subsequent FE analysis. To demonstrate the importance of our method in a clinical context, a subject-specific mesh is used to simulate tongue's biomechanical response to the activation of an important tongue muscle, before and after cancer surgery.
NASA Astrophysics Data System (ADS)
Kaiser, Markus; John, Matthias; Borsdorf, Anja; Mountney, Peter; Ionasec, Razvan; Nöttling, Alois; Kiefer, Philipp; Seeburger, Jörg; Neumuth, Thomas
2013-03-01
For transcatheter-based minimally invasive procedures in structural heart disease ultrasound and X-ray are the two enabling imaging modalities. A live fusion of both real-time modalities can potentially improve the workflow and the catheter navigation by combining the excellent instrument imaging of X-ray with the high-quality soft tissue imaging of ultrasound. A recently published approach to fuse X-ray fluoroscopy with trans-esophageal echo (TEE) registers the ultrasound probe to X-ray images by a 2D-3D registration method which inherently provides a registration of ultrasound images to X-ray images. In this paper, we significantly accelerate the 2D-3D registration method in this context. The main novelty is to generate the projection images (DRR) of the 3D object not via volume ray-casting but instead via a fast rendering of triangular meshes. This is possible, because in the setting for TEE/X-ray fusion the 3D geometry of the ultrasound probe is known in advance and their main components can be described by triangular meshes. We show that the new approach can achieve a speedup factor up to 65 and does not affect the registration accuracy when used in conjunction with the gradient correlation similarity measure. The improvement is independent of the underlying registration optimizer. Based on the results, a TEE/X-ray fusion could be performed with a higher frame rate and a shorter time lag towards real-time registration performance. The approach could potentially accelerate other applications of 2D-3D registrations, e.g. the registration of implant models with X-ray images.
Efficient texture mapping by adaptive mesh division in mesh-based computer generated hologram.
Ji, Yeong-Min; Yeom, Hanju-; Park, Jae-Hyeung
2016-11-28
We propose a method that achieves efficient texture mapping in fully-analytic computer generated holograms based on triangular meshes. In computer graphics, the texture mapping is commonly used to represent the details of objects without increasing the number of the triangular meshes. In fully-analytic triangular-mesh-based computer generated holograms, however, those methods cannot be directly applied because each mesh cannot have arbitrary amplitude distribution inside the triangular mesh area in order to keep the analytic representation. In this paper, we propose an efficient texture mapping method for fully-analytic mesh-based computer generated hologram. The proposed method uses an adaptive triangular mesh division to minimize the increase of the number of the triangular meshes for the given texture image data. The geometrical similarity relationship between the original triangular mesh and the divided one is also exploited to obtain the angular spectrum of the divided mesh from pre-calculated data for the original one. As a result, the proposed method enables to obtain the computer generated hologram of high details with much smaller computation time in comparison with the brute-force approach. The feasibility of the proposed method is confirmed by simulations and optical experiments.
Array-based Hierarchical Mesh Generation in Parallel
Ray, Navamita; Grindeanu, Iulian; Zhao, Xinglin; ...
2015-11-03
In this paper, we describe an array-based hierarchical mesh generation capability through uniform refinement of unstructured meshes for efficient solution of PDE's using finite element methods and multigrid solvers. A multi-degree, multi-dimensional and multi-level framework is designed to generate the nested hierarchies from an initial mesh that can be used for a number of purposes such as multi-level methods to generating large meshes. The capability is developed under the parallel mesh framework “Mesh Oriented dAtaBase” a.k.a MOAB. We describe the underlying data structures and algorithms to generate such hierarchies and present numerical results for computational efficiency and mesh quality. Inmore » conclusion, we also present results to demonstrate the applicability of the developed capability to a multigrid finite-element solver.« less
Array-based Hierarchical Mesh Generation in Parallel
Ray, Navamita; Grindeanu, Iulian; Zhao, Xinglin; Mahadevan, Vijay; Jiao, Xiangmin
2015-11-03
In this paper, we describe an array-based hierarchical mesh generation capability through uniform refinement of unstructured meshes for efficient solution of PDE's using finite element methods and multigrid solvers. A multi-degree, multi-dimensional and multi-level framework is designed to generate the nested hierarchies from an initial mesh that can be used for a number of purposes such as multi-level methods to generating large meshes. The capability is developed under the parallel mesh framework “Mesh Oriented dAtaBase” a.k.a MOAB. We describe the underlying data structures and algorithms to generate such hierarchies and present numerical results for computational efficiency and mesh quality. In conclusion, we also present results to demonstrate the applicability of the developed capability to a multigrid finite-element solver.
Model Development for Solving 3D Landslide Generated Tsunami.
NASA Astrophysics Data System (ADS)
Hu, Shun-Kai; Wu, Tso-Ren
2017-04-01
Landslide generated tsunami often caused severe damage in the near-source coastal area. However, the dynamics of the wave generation between landslide and tsunami has not been well studied. In this paper, we explored the generation process numerically. Surface-piercing rock slide was one of the focuses. The kinematic of the rocks was described by the newly developed egg-shape Moving-Solid-Algorithm (MSA). The egg-shape, including ellipsoid-shape and sphere, was divided into four curvatures. Discrete-Element-Method (DEM) will be adopted to calculate the solid motion. The result was coupled with a fluid dynamic model, Splash3D, by solving the full Navier-Stokes equations. The violent breaking waves was described by Volume-of-Fluid (VOF) method with Piecewise-Linear-Interface-Calculation (PLIC) surface reconstruction algorithm. In this study, we present a series of numerical experiment to validation the accuracy of MSA. Cases of floating block and landslide box were performed. Good comparison results can be seen. As for the egg-shape MSA, the case of water entry sphere was chosen for validation. Very good results in terms of the displacement and the shape of air cavity can be seen. The characteristics of landslide tsunamis were presented. At the end, the boulder pushed by high-energy waves will simulated and discussed.
An interface-fitted mesh generator and virtual element methods for elliptic interface problems
NASA Astrophysics Data System (ADS)
Chen, Long; Wei, Huayi; Wen, Min
2017-04-01
A simple and efficient interface-fitted mesh generation algorithm which can produce a semi-structured interface-fitted mesh in two and three dimensions quickly is developed in this paper. Elements in such interface-fitted meshes are not restricted to simplices but can be polygons or polyhedra. Especially in 3D, the polyhedra instead of tetrahedra can avoid slivers. Virtual element methods are applied to solve elliptic interface problems with solutions and flux jump conditions. Algebraic multigrid solvers are used to solve the resulting linear algebraic system. Numerical results are presented to illustrate the effectiveness of our method.
Garcia-Cantero, Juan J.; Brito, Juan P.; Mata, Susana; Bayona, Sofia; Pastor, Luis
2017-01-01
Gaining a better understanding of the human brain continues to be one of the greatest challenges for science, largely because of the overwhelming complexity of the brain and the difficulty of analyzing the features and behavior of dense neural networks. Regarding analysis, 3D visualization has proven to be a useful tool for the evaluation of complex systems. However, the large number of neurons in non-trivial circuits, together with their intricate geometry, makes the visualization of a neuronal scenario an extremely challenging computational problem. Previous work in this area dealt with the generation of 3D polygonal meshes that approximated the cells’ overall anatomy but did not attempt to deal with the extremely high storage and computational cost required to manage a complex scene. This paper presents NeuroTessMesh, a tool specifically designed to cope with many of the problems associated with the visualization of neural circuits that are comprised of large numbers of cells. In addition, this method facilitates the recovery and visualization of the 3D geometry of cells included in databases, such as NeuroMorpho, and provides the tools needed to approximate missing information such as the soma’s morphology. This method takes as its only input the available compact, yet incomplete, morphological tracings of the cells as acquired by neuroscientists. It uses a multiresolution approach that combines an initial, coarse mesh generation with subsequent on-the-fly adaptive mesh refinement stages using tessellation shaders. For the coarse mesh generation, a novel approach, based on the Finite Element Method, allows approximation of the 3D shape of the soma from its incomplete description. Subsequently, the adaptive refinement process performed in the graphic card generates meshes that provide good visual quality geometries at a reasonable computational cost, both in terms of memory and rendering time. All the described techniques have been integrated into NeuroTessMesh
Generation Of 3d Periodic Internal Wave Beams:
NASA Astrophysics Data System (ADS)
Chashechkin, Yuli D.; Vasiliev, Alexey Yu.
We study generation of 2D and 3D periodic internal wave beams in continuously strat- ified viscous liquid basing on a complete set of governing equations and exact bound- ary conditions that is no-slip for velocity and attenuation of all disturbances at infinite distance from the source. The linearized governing equations are solved by an integral transform method. A total set of dispersion equation roots contains terms correspond- ing to internal waves and additional roots describing two kinds of periodic boundary layers. The first one is a viscous boundary layer and has an analogue that is a periodic or Stokes' layer in a homogeneous fluid. Its thickness is defined by a kinematic viscos- ity coefficient and a buoyancy frequency. The second one, that is an internal boundary layer, is a specific feature of stratified flows. Its thickness besides the Stokes' scale contains additional factor depending on relative wave frequency and geometry of the problem that is on the local slope of emitting surface and a direction of the waves propagation. We have constructed exact solutions of linear problems describing gen- eration of 2D waves by a strip and 3D by a rectangular with an arbitrary ratio of sides moving along or normally to a sloping plane. We also calculated the wave pattern gen- erated by a part of a vertical cylinder surface with different ratios of intrinsic scales that is of cylinder radius, thickness of the boundary layer and internal viscous scale. All solutions are regularly matched between themselves in limiting cases. The spatial decay of the waves depends on dimension and geometry of the problem. Non-linear generation of internal waves by the Stokes' boundary layer on a periodically rotating horizontal disk or by interacting boundary layers on an arbitrary moving strip is in- vestigated. We found conditions of generation of the main frequency and its second harmonic. In experiments periodic waves beams from different sources are visualised by the
3D Adaptive Mesh Refinement Simulations of Pellet Injection in Tokamaks
R. Samtaney; S.C. Jardin; P. Colella; D.F. Martin
2003-10-20
We present results of Adaptive Mesh Refinement (AMR) simulations of the pellet injection process, a proven method of refueling tokamaks. AMR is a computationally efficient way to provide the resolution required to simulate realistic pellet sizes relative to device dimensions. The mathematical model comprises of single-fluid MHD equations with source terms in the continuity equation along with a pellet ablation rate model. The numerical method developed is an explicit unsplit upwinding treatment of the 8-wave formulation, coupled with a MAC projection method to enforce the solenoidal property of the magnetic field. The Chombo framework is used for AMR. The role of the E x B drift in mass redistribution during inside and outside pellet injections is emphasized.
Registration of 3D point clouds and meshes: a survey from rigid to nonrigid.
Tam, Gary K L; Cheng, Zhi-Quan; Lai, Yu-Kun; Langbein, Frank C; Liu, Yonghuai; Marshall, David; Martin, Ralph R; Sun, Xian-Fang; Rosin, Paul L
2013-07-01
Three-dimensional surface registration transforms multiple three-dimensional data sets into the same coordinate system so as to align overlapping components of these sets. Recent surveys have covered different aspects of either rigid or nonrigid registration, but seldom discuss them as a whole. Our study serves two purposes: 1) To give a comprehensive survey of both types of registration, focusing on three-dimensional point clouds and meshes and 2) to provide a better understanding of registration from the perspective of data fitting. Registration is closely related to data fitting in which it comprises three core interwoven components: model selection, correspondences and constraints, and optimization. Study of these components 1) provides a basis for comparison of the novelties of different techniques, 2) reveals the similarity of rigid and nonrigid registration in terms of problem representations, and 3) shows how overfitting arises in nonrigid registration and the reasons for increasing interest in intrinsic techniques. We further summarize some practical issues of registration which include initializations and evaluations, and discuss some of our own observations, insights and foreseeable research trends.
3D Boltzmann Simulation of the Io's Plasma Environment with Adaptive Mesh and Particle Refinement
NASA Astrophysics Data System (ADS)
Lipatov, A. S.; Combi, M. R.
2002-12-01
The global dynamics of the ionized and neutral components in the environment of Io plays an important role in the interaction of Jupiter's corotating magnetospheric plasma with Io [Combi et al., 2002; 1998; Kabin et al., 2001]. The stationary simulation of this problem was done in the MHD [Combi et al., 1998; Linker et al, 1998; Kabin et al., 2001] and the electrodynamic [Saur et al., 1999] approaches. In this report, we develop a method of kinetic ion-neutral simulation, which is based on a multiscale adaptive mesh, particle and algorithm refinement. This method employs the fluid description for electrons whereas for ions the drift-kinetic and particle approaches are used. This method takes into account charge-exchange and photoionization processes. The first results of such simulation of the dynamics of ions in the Io's environment are discussed in this report. ~ M R Combi et al., J. Geophys. Res., 103, 9071, 1998. M R Combi, T I Gombosi, K Kabin, Atmospheres in the Solar System: Comparative\\ Aeronomy. Geophys. Monograph Series, 130, 151, 2002. K Kabin et al., Planetary and Space Sci., 49, 337, 2001. J A Linker et al., J. Geophys. Res., 103(E9), 19867, 1998. J Saur et al., J. Geophys. Res., 104, 25105, 1999.
3D Numerical Simulation on the Rockslide Generated Tsunamis
NASA Astrophysics Data System (ADS)
Chuang, M.; Wu, T.; Wang, C.; Chu, C.
2013-12-01
The rockslide generated tsunami is one of the most devastating nature hazards. However, the involvement of the moving obstacle and dynamic free-surface movement makes the numerical simulation a difficult task. To describe both the fluid motion and solid movement at the same time, we newly developed a two-way fully-coupled moving solid algorithm with 3D LES turbulent model. The free-surface movement is tracked by volume of fluid (VOF) method. The two-step projection method is adopted to solve the Navier-Stokes type government equations. In the new moving solid algorithm, a fictitious body force is implicitly prescribed in MAC correction step to make the cell-center velocity satisfied with the obstacle velocity. We called this method the implicit velocity method (IVM). Because no extra terms are added to the pressure Poission correction, the pressure field of the fluid part is stable, which is the key of the two-way fluid-solid coupling. Because no real solid material is presented in the IVM, the time marching step is not restricted to the smallest effective grid size. Also, because the fictitious force is implicitly added to the correction step, the resulting velocity is accurate and fully coupled with the resulting pressure field. We validated the IVM by simulating a floating box moving up and down on the free-surface. We presented the time-history obstacle trajectory and compared it with the experimental data. Very accurate result can be seen in terms of the oscillating amplitude and the period (Fig. 1). We also presented the free-surface comparison with the high-speed snapshots. At the end, the IVM was used to study the rock-slide generated tsunamis (Liu et al., 2005). Good validations on the slide trajectory and the free-surface movement will be presented in the full paper. From the simulation results (Fig. 2), we observed that the rockslide generated waves are manly caused by the rebounding waves from two sides of the sliding rock after the water is dragging
High resolution 3D imaging of synchrotron generated microbeams
Gagliardi, Frank M.; Cornelius, Iwan; Blencowe, Anton; Franich, Rick D.; Geso, Moshi
2015-12-15
Purpose: Microbeam radiation therapy (MRT) techniques are under investigation at synchrotrons worldwide. Favourable outcomes from animal and cell culture studies have proven the efficacy of MRT. The aim of MRT researchers currently is to progress to human clinical trials in the near future. The purpose of this study was to demonstrate the high resolution and 3D imaging of synchrotron generated microbeams in PRESAGE® dosimeters using laser fluorescence confocal microscopy. Methods: Water equivalent PRESAGE® dosimeters were fabricated and irradiated with microbeams on the Imaging and Medical Beamline at the Australian Synchrotron. Microbeam arrays comprised of microbeams 25–50 μm wide with 200 or 400 μm peak-to-peak spacing were delivered as single, cross-fire, multidirectional, and interspersed arrays. Imaging of the dosimeters was performed using a NIKON A1 laser fluorescence confocal microscope. Results: The spatial fractionation of the MRT beams was clearly visible in 2D and up to 9 mm in depth. Individual microbeams were easily resolved with the full width at half maximum of microbeams measured on images with resolutions of as low as 0.09 μm/pixel. Profiles obtained demonstrated the change of the peak-to-valley dose ratio for interspersed MRT microbeam arrays and subtle variations in the sample positioning by the sample stage goniometer were measured. Conclusions: Laser fluorescence confocal microscopy of MRT irradiated PRESAGE® dosimeters has been validated in this study as a high resolution imaging tool for the independent spatial and geometrical verification of MRT beam delivery.
Automated robust generation of compact 3D statistical shape models
NASA Astrophysics Data System (ADS)
Vrtovec, Tomaz; Likar, Bostjan; Tomazevic, Dejan; Pernus, Franjo
2004-05-01
Ascertaining the detailed shape and spatial arrangement of anatomical structures is important not only within diagnostic settings but also in the areas of planning, simulation, intraoperative navigation, and tracking of pathology. Robust, accurate and efficient automated segmentation of anatomical structures is difficult because of their complexity and inter-patient variability. Furthermore, the position of the patient during image acquisition, the imaging device and protocol, image resolution, and other factors induce additional variations in shape and appearance. Statistical shape models (SSMs) have proven quite successful in capturing structural variability. A possible approach to obtain a 3D SSM is to extract reference voxels by precisely segmenting the structure in one, reference image. The corresponding voxels in other images are determined by registering the reference image to each other image. The SSM obtained in this way describes statistically plausible shape variations over the given population as well as variations due to imperfect registration. In this paper, we present a completely automated method that significantly reduces shape variations induced by imperfect registration, thus allowing a more accurate description of variations. At each iteration, the derived SSM is used for coarse registration, which is further improved by describing finer variations of the structure. The method was tested on 64 lumbar spinal column CT scans, from which 23, 38, 45, 46 and 42 volumes of interest containing vertebra L1, L2, L3, L4 and L5, respectively, were extracted. Separate SSMs were generated for each vertebra. The results show that the method is capable of reducing the variations induced by registration errors.
Tomographic mesh generation for OSEM reconstruction of SPECT images
NASA Astrophysics Data System (ADS)
Lu, Yao; Yu, Bo; Vogelsang, Levon; Krol, Andrzej; Xu, Yuesheng; Hu, Xiaofei; Feiglin, David
2009-02-01
To improve quality of OSEM SPECT reconstruction in the mesh domain, we implemented an adaptive mesh generation method that produces tomographic mesh consisting of triangular elements with size and density commensurate with geometric detail of the objects. Node density and element size change smoothly as a function of distance from the edges and edge curvature without creation of 'bad' elements. Tomographic performance of mesh-based OSEM reconstruction is controlled by the tomographic mesh structure, i.e. node density distribution, which in turn is ruled by the number of key points on the boundaries. A greedy algorithm is used to influence the distribution of nodes on the boundaries. The relationship between tomographic mesh properties and OSEM reconstruction quality has been investigated. We conclude that by selecting adequate number of key points, one can produce a tomographic mesh with lowest number of nodes that is sufficient to provide desired quality of reconstructed images, appropriate for the imaging system properties.
Developments and trends in three-dimensional mesh generation
NASA Technical Reports Server (NTRS)
Baker, Timothy J.
1989-01-01
An intense research effort over the last few years has produced several competing and apparently diverse methods for generating meshes. Recent progress is reviewed and the central themes are emphasized which form a solid foundation for future developments in mesh generation.
Amato, Giuseppe; Romano, Giorgio; Agrusa, Antonino; Marasa, Salvatore; Cocorullo, Gianfranco; Gulotta, Gaspare; Goetze, Thorsten; Puleio, Roberto
2015-01-01
Despite improvements in prosthetics and surgical techniques, the rate of complications following inguinal hernia repair remains high. Among these, discomfort and chronic pain have become a source of increasing concern among surgeons. Poor quality of tissue ingrowth, such as thin scar plates or shrinking scars-typical results with conventional static implants and plugs-may contribute to these adverse events. Recently, a new type of 3D dynamically responsive implant was introduced to the market. This device, designed to be placed fixation-free, seems to induce ingrowth of viable and structured tissue instead of regressive fibrotic scarring. To elucidate the differences in biologic response between the conventional static meshes and this 3D dynamically responsive implant, a histological comparison was planned. The aim of this study was to determine the quality of tissue incorporation in both types of implants excised after short, medium, and long periods post-implantation. The results showed large differences in the biologic responses between the two implant types. Histologically, the 3D dynamic implant showed development of tissue elements more similar to natural abdominal wall structures, such as the ingrowth of loose and well-hydrated connective tissue, well-formed vascular structures, elastic fibers, and mature nerves, with negligible or absent inflammatory response. All these characteristics were completely absent in the conventional static implants, where a persistent inflammatory reaction was associated with thin, hardened, and shrunken fibrotic scar formation. Consequently, as herniation is a degenerative process, the 3D dynamic implants, which induce regeneration of the typical groin components, seem to address its pathogenesis.
3-D grid refinement using the University of Michigan adaptive mesh library for a pure advective test
NASA Astrophysics Data System (ADS)
Oehmke, R.; Vandenberg, D.; Andronova, N.; Penner, J.; Stout, Q.; Zubov, V.; Jablonowski, C.
2008-05-01
The numerical representation of the partial differential equations (PDE) for high resolution atmospheric dynamical and physical features requires division of the atmospheric volume into a set of 3D grids, each of which has a not quite rectangular form. Each location on the grid contains multiple data that together represent the state of Earth's atmosphere. For successful numerical integration of the PDEs the size of each grid box is used to define the Courant-Friedrichs-Levi criterion in setting the time step. 3D adaptive representations of a sphere are needed to represent the evolution of clouds. In this paper we present the University of Michigan adaptive mesh library - a library that supports the production of parallel codes with use of adaptation on a sphere. The library manages the block-structured data layout, handles ghost cell updates among neighboring blocks and splits blocks as refinements occur. The library has several modules that provide a layer of abstraction for adaptive refinement: blocks, which contain individual cells of user data; shells — the global geometry for the problem, including a sphere, reduced sphere, and now a 3D sphere; a load balancer for placement of blocks onto processors; and a communication support layer which encapsulates all data movement. Users provide data manipulation functions for performing interpolation of user data when refining blocks. We rigorously test the library using refinement of the modeled vertical transport of a tracer with prescribed atmospheric sources and sinks. It is both a 2 and a 3D test, and bridges the performance of the model's dynamics and physics needed for inclusion of cloud formation.
A two-dimensional adaptive mesh generation method
NASA Astrophysics Data System (ADS)
Altas, Irfan; Stephenson, John W.
1991-05-01
The present, two-dimensional adaptive mesh-generation method allows selective modification of a small portion of the mesh without affecting large areas of adjacent mesh-points, and is applicable with or without boundary-fitted coordinate-generation procedures. The cases of differential equation discretization by, on the one hand, classical difference formulas designed for uniform meshes, and on the other the present difference formulas, are illustrated through the application of the method to the Hiemenz flow for which the Navier-Stokes equation's exact solution is known, as well as to a two-dimensional viscous internal flow problem.
Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images
NASA Astrophysics Data System (ADS)
Su, Yi; Teo, S.-K.; Lim, C. W.; Zhong, L.; Tan, R. S.
2015-03-01
In this work, we develop an automatic method to generate a set of 4D 1-to-1 corresponding surface meshes of the left ventricle (LV) endocardial surface which are motion registered over the whole cardiac cycle. These 4D meshes have 1- to-1 point correspondence over the entire set, and is suitable for advanced computational processing, such as shape analysis, motion analysis and finite element modelling. The inputs to the method are the set of 3D LV endocardial surface meshes of the different frames/phases of the cardiac cycle. Each of these meshes is reconstructed independently from border-delineated MR images and they have no correspondence in terms of number of vertices/points and mesh connectivity. To generate point correspondence, the first frame of the LV mesh model is used as a template to be matched to the shape of the meshes in the subsequent phases. There are two stages in the mesh correspondence process: (1) a coarse matching phase, and (2) a fine matching phase. In the coarse matching phase, an initial rough matching between the template and the target is achieved using a radial basis function (RBF) morphing process. The feature points on the template and target meshes are automatically identified using a 16-segment nomenclature of the LV. In the fine matching phase, a progressive mesh projection process is used to conform the rough estimate to fit the exact shape of the target. In addition, an optimization-based smoothing process is used to achieve superior mesh quality and continuous point motion.
NASA Astrophysics Data System (ADS)
Cai, Hongzhu; Hu, Xiangyun; Li, Jianhui; Endo, Masashi; Xiong, Bin
2017-02-01
We solve the 3D controlled-source electromagnetic (CSEM) problem using the edge-based finite element method. The modeling domain is discretized using unstructured tetrahedral mesh. We adopt the total field formulation for the quasi-static variant of Maxwell's equation and the computation cost to calculate the primary field can be saved. We adopt a new boundary condition which approximate the total field on the boundary by the primary field corresponding to the layered earth approximation of the complicated conductivity model. The primary field on the modeling boundary is calculated using fast Hankel transform. By using this new type of boundary condition, the computation cost can be reduced significantly and the modeling accuracy can be improved. We consider that the conductivity can be anisotropic. We solve the finite element system of equations using a parallelized multifrontal solver which works efficiently for multiple source and large scale electromagnetic modeling.
3D Moving-Mesh Simulations of Galactic Center Cloud G2
NASA Astrophysics Data System (ADS)
Wilson, Julia; Fragile, P. C.; Anninos, P.; Murray, S. D.
2013-01-01
Using three-dimensional, moving-mesh simulations, we investigate the future evolution of the recently discovered gas cloud G2 traveling through the galactic center. We consider the case of a spherical cloud initially in pressure equilibrium with the background. Our suite of simulations explores the following parameters: the equation of state, radial profiles of the background gas, and start times for the evolution. Our primary focus is on how the fate of this cloud will affect the future activity of Sgr A*. From our simulations we expect an average feeding rate in the range of 5 - 19 × 10-8M⊙ yr-1 beginning in 2013 and lasting for at least 7 years (our simulations stop in year 2020). The accretion varies by less than a factor of three on timescales ≤ 1 month, and shows no more than a factor of 10 difference between the maximum and minimum observed rates within any given model. These rates are comparable to the current estimated accretion rate in the immediate vicinity of Sgr A*, although they represent only a small (≤ 5%) increase over the current expected feeding rate at the effective inner boundary of our simulations (r = 750RS ≈ 1015 cm), where RS is the Schwarzschild radius of the black hole. Therefore, the break up of cloud G2 may have only a minimal effect on the brightness and variability of Sgr A* over the next decade. This is because current models of the galactic center predict that most of the gas will be caught up in outflows. However, if the accreted G2 material can remain cold, it may not mix well with the hot, diffuse background gas, and instead accrete efficiently onto Sgr A*. Further observations of G2 will give us an unprecedented opportunity to test this idea. The break up of the cloud itself may also be observable. By tracking the amount of cloud energy that is dissipated during our simulations, we are able to get a rough estimate of the luminosity associated with its tidal disruption; we find values of a few 1036 erg s-1.
Some mesh generation requirements and methods
NASA Technical Reports Server (NTRS)
Dickson, L. J.
1978-01-01
Discretized solution algorithms, which find solutions of field equations in a two or three dimensional field, generally use meshes which are fitted to the field boundary to allow convenient formulation of boundary conditions there. A mesh is defined to be the image of a rectangular grid in computational space under a mesh mapping which maps computational space into physical space. It is not necessary that all of computational space be mapped onto the region of interest in physical space. Parts of it can be excised to give a better fit to the boundary. Many different excisions can be made to fit a single boundary; the choice depends on the mesh arrangement desired in the field.
Chedid, R.; Najjar, N.
1996-09-01
One of the inconveniences associated with the existing finite-element packages is the need for an educated user to develop a correct mesh at the preprocessing level. Procedures which start with a coarse mesh and attempt serious refinements, as is the case in most adaptive finite-element packages, are time consuming and costly. Hence, it is very important to develop a tool that can provide a mesh that either leads immediately to an acceptable solution, or would require fewer correcting steps to achieve better results. In this paper, the authors present a technique for automatic mesh generation based on artificial neural networks (ANN). The essence of this technique is to predict the mesh density distribution of a given model, and then supply this information to a Kohonen neural network which provides the final mesh. Prediction of mesh density is accomplished by a simple feedforward neural network which has the ability to learn the relationship between mesh density and model geometric features. It will be shown that ANN are able to recognize delicate areas where a sharp variation of the magnetic field is expected. Examples of 2-D models are provided to illustrate the usefulness of the proposed technique.
NASA Astrophysics Data System (ADS)
O'Hara, Ryan P.; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M.; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N.
2016-03-01
Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.
From medical images to flow computations without user-generated meshes.
Dillard, Seth I; Mousel, John A; Shrestha, Liza; Raghavan, Madhavan L; Vigmostad, Sarah C
2014-10-01
Biomedical flow computations in patient-specific geometries require integrating image acquisition and processing with fluid flow solvers. Typically, image-based modeling processes involve several steps, such as image segmentation, surface mesh generation, volumetric flow mesh generation, and finally, computational simulation. These steps are performed separately, often using separate pieces of software, and each step requires considerable expertise and investment of time on the part of the user. In this paper, an alternative framework is presented in which the entire image-based modeling process is performed on a Cartesian domain where the image is embedded within the domain as an implicit surface. Thus, the framework circumvents the need for generating surface meshes to fit complex geometries and subsequent creation of body-fitted flow meshes. Cartesian mesh pruning, local mesh refinement, and massive parallelization provide computational efficiency; the image-to-computation techniques adopted are chosen to be suitable for distributed memory architectures. The complete framework is demonstrated with flow calculations computed in two 3D image reconstructions of geometrically dissimilar intracranial aneurysms. The flow calculations are performed on multiprocessor computer architectures and are compared against calculations performed with a standard multistep route.
From medical images to flow computations without user-generated meshes
Dillard, Seth I.; Mousel, John A.; Shrestha, Liza; Raghavan, Madhavan L.; Vigmostad, Sarah C.
2014-01-01
SUMMARY Biomedical flow computations in patient-specific geometries require integrating image acquisition and processing with fluid flow solvers. Typically, image-based modeling processes involve several steps, such as image segmentation, surface mesh generation, volumetric flow mesh generation, and finally computational simulation. These steps are performed separately, often using separate pieces of software, and each step requires considerable expertise and investment of time on the part of the user. In this paper an alternative framework is presented in which the entire image-based modeling process is performed on a Cartesian domain where the image is embedded within the domain as an implicit surface. Thus the framework circumvents the need for generating surface meshes to fit complex geometries and subsequent creation of body-fitted flow meshes. Cartesian mesh pruning, local mesh refinement, and massive parallelization provide computational efficiency; the image-to-computation techniques adopted are chosen to be suitable for distributed memory architectures. The complete framework is demonstrated with flow calculations computed in two 3D image reconstructions of geometrically dissimilar intracranial aneurysms. The flow calculations are performed on multiprocessor computer architectures and are compared against calculations performed with a standard multi-step route. PMID:24753504
Hexahedral mesh generation via the dual arrangement of surfaces
Mitchell, S.A.; Tautges, T.J.
1997-12-31
Given a general three-dimensional geometry with a prescribed quadrilateral surface mesh, the authors consider the problem of constructing a hexahedral mesh of the geometry whose boundary is exactly the prescribed surface mesh. Due to the specialized topology of hexahedra, this problem is more difficult than the analogous one for tetrahedra. Folklore has maintained that a surface mesh must have a constrained structure in order for there to exist a compatible hexahedral mesh. However, they have proof that a surface mesh need only satisfy mild parity conditions, depending on the topology of the three-dimensional geometry, for there to exist a compatible hexahedral mesh. The proof is based on the realization that a hexahedral mesh is dual to an arrangement of surfaces, and the quadrilateral surface mesh is dual to the arrangement of curves bounding these surfaces. The proof is constructive and they are currently developing an algorithm called Whisker Weaving (WW) that mirrors the proof steps. Given the bounding curves, WW builds the topological structure of an arrangement of surfaces having those curves as its boundary. WW progresses in an advancing front manner. Certain local rules are applied to avoid structures that lead to poor mesh quality. Also, after the arrangement is constructed, additional surfaces are inserted to separate features, so e.g., no two hexahedra share more than one quadrilateral face. The algorithm has generated meshes for certain non-trivial problems, but is currently unreliable. The authors are exploring strategies for consistently selecting which portion of the surface arrangement to advance based on the existence proof. This should lead us to a robust algorithm for arbitrary geometries and surface meshes.
The 3D Euler solutions using automated Cartesian grid generation
NASA Technical Reports Server (NTRS)
Melton, John E.; Enomoto, Francis Y.; Berger, Marsha J.
1993-01-01
Viewgraphs on 3-dimensional Euler solutions using automated Cartesian grid generation are presented. Topics covered include: computational fluid dynamics (CFD) and the design cycle; Cartesian grid strategy; structured body fit; grid generation; prolate spheroid; and ONERA M6 wing.
Volume Decomposition and Feature Recognition for Hexahedral Mesh Generation
GADH,RAJIT; LU,YONG; TAUTGES,TIMOTHY J.
1999-09-27
Considerable progress has been made on automatic hexahedral mesh generation in recent years. Several automatic meshing algorithms have proven to be very reliable on certain classes of geometry. While it is always worth pursuing general algorithms viable on more general geometry, a combination of the well-established algorithms is ready to take on classes of complicated geometry. By partitioning the entire geometry into meshable pieces matched with appropriate meshing algorithm the original geometry becomes meshable and may achieve better mesh quality. Each meshable portion is recognized as a meshing feature. This paper, which is a part of the feature based meshing methodology, presents the work on shape recognition and volume decomposition to automatically decompose a CAD model into meshable volumes. There are four phases in this approach: (1) Feature Determination to extinct decomposition features, (2) Cutting Surfaces Generation to form the ''tailored'' cutting surfaces, (3) Body Decomposition to get the imprinted volumes; and (4) Meshing Algorithm Assignment to match volumes decomposed with appropriate meshing algorithms. The feature determination procedure is based on the CLoop feature recognition algorithm that is extended to be more general. Results are demonstrated over several parts with complicated topology and geometry.
Vertical Scan (V-SCAN) for 3-D Grid Adaptive Mesh Refinement for an atmospheric Model Dynamical Core
NASA Astrophysics Data System (ADS)
Andronova, N. G.; Vandenberg, D.; Oehmke, R.; Stout, Q. F.; Penner, J. E.
2009-12-01
One of the major building blocks of a rigorous representation of cloud evolution in global atmospheric models is a parallel adaptive grid MPI-based communication library (an Adaptive Blocks for Locally Cartesian Topologies library -- ABLCarT), which manages the block-structured data layout, handles ghost cell updates among neighboring blocks and splits a block as refinements occur. The library has several modules that provide a layer of abstraction for adaptive refinement: blocks, which contain individual cells of user data; shells - the global geometry for the problem, including a sphere, reduced sphere, and now a 3D sphere; a load balancer for placement of blocks onto processors; and a communication support layer which encapsulates all data movement. A major performance concern with adaptive mesh refinement is how to represent calculations that have need to be sequenced in a particular order in a direction, such as calculating integrals along a specific path (e.g. atmospheric pressure or geopotential in the vertical dimension). This concern is compounded if the blocks have varying levels of refinement, or are scattered across different processors, as can be the case in parallel computing. In this paper we describe an implementation in ABLCarT of a vertical scan operation, which allows computing along vertical paths in the correct order across blocks transparent to their resolution and processor location. We test this functionality on a 2D and a 3D advection problem, which tests the performance of the model’s dynamics (transport) and physics (sources and sinks) for different model resolutions needed for inclusion of cloud formation.
Hyperchaos generated from 3D chaotic systems using PI controller
NASA Astrophysics Data System (ADS)
Devi, V. R.; Farooq, Farsana; Gopakumar, K.
2017-07-01
Hyperchaotic systems have chaotic behavior with at least two positive Lyapunov exponents and the minimum required system dimension is four. In this paper, a 3D chaotic system is converted into hyperchaotic system using PI controller in the feedback path. Integral controller is responsible for increase in order of the system. The hyperchaotic nature is verified by the existence of two positive Lyapunov exponents and using bifurcation diagrams. The system is hyperchaotic in several different regions of the parameters. The result shows that this method can not only enhance or suppress chaotic behavior, but also induces chaos in non-chaotic parameter ranges. The proposed method is applied to a secure communication system by means of encryption and decryption of a message using hyperchaotic system.
Adaptive mesh generation for viscous flows using Delaunay triangulation
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.
1990-01-01
A method for generating an unstructured triangular mesh in two dimensions, suitable for computing high Reynolds number flows over arbitrary configurations is presented. The method is based on a Delaunay triangulation, which is performed in a locally stretched space, in order to obtain very high aspect ratio triangles in the boundary layer and the wake regions. It is shown how the method can be coupled with an unstructured Navier-Stokes solver to produce a solution adaptive mesh generation procedure for viscous flows.
Adaptive mesh generation for viscous flows using Delaunay triangulation
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.
1988-01-01
A method for generating an unstructured triangular mesh in two dimensions, suitable for computing high Reynolds number flows over arbitrary configurations is presented. The method is based on a Delaunay triangulation, which is performed in a locally stretched space, in order to obtain very high aspect ratio triangles in the boundary layer and the wake regions. It is shown how the method can be coupled with an unstructured Navier-Stokes solver to produce a solution adaptive mesh generation procedure for viscous flows.
Drag Prediction for the DLR-F6 Wing/Body and DPW Wing using CFL3D and OVERFLOW Overset Mesh
NASA Technical Reports Server (NTRS)
Sclanfani, Anthony J.; Vassberg, John C.; Harrison, Neal A.; DeHaan, Mark A.; Rumsey, Christopher L.; Rivers, S. Melissa; Morrison, Joseph H.
2007-01-01
A series of overset grids was generated in response to the 3rd AIAA CFD Drag Prediction Workshop (DPW-III) which preceded the 25th Applied Aerodynamics Conference in June 2006. DPW-III focused on accurate drag prediction for wing/body and wing-alone configurations. The grid series built for each configuration consists of a coarse, medium, fine, and extra-fine mesh. The medium mesh is first constructed using the current state of best practices for overset grid generation. The medium mesh is then coarsened and enhanced by applying a factor of 1.5 to each (I,J,K) dimension. The resulting set of parametrically equivalent grids increase in size by a factor of roughly 3.5 from one level to the next denser level. CFD simulations were performed on the overset grids using two different RANS flow solvers: CFL3D and OVERFLOW. The results were post-processed using Richardson extrapolation to approximate grid converged values of lift, drag, pitching moment, and angle-of-attack at the design condition. This technique appears to work well if the solution does not contain large regions of separated flow (similar to that seen n the DLR-F6 results) and appropriate grid densities are selected. The extra-fine grid data helped to establish asymptotic grid convergence for both the OVERFLOW FX2B wing/body results and the OVERFLOW DPW-W1/W2 wing-alone results. More CFL3D data is needed to establish grid convergence trends. The medium grid was utilized beyond the grid convergence study by running each configuration at several angles-of-attack so drag polars and lift/pitching moment curves could be evaluated. The alpha sweep results are used to compare data across configurations as well as across flow solvers. With the exception of the wing/body drag polar, the two codes compare well qualitatively showing consistent incremental trends and similar wing pressure comparisons.
NASA Astrophysics Data System (ADS)
Fang, F.; Zhang, T.; Pavlidis, D.; Pain, C. C.; Buchan, A. G.; Navon, I. M.
2014-10-01
A novel reduced order model (ROM) based on proper orthogonal decomposition (POD) has been developed for a finite-element (FE) adaptive mesh air pollution model. A quadratic expansion of the non-linear terms is employed to ensure the method remained efficient. This is the first time such an approach has been applied to air pollution LES turbulent simulation through three dimensional landscapes. The novelty of this work also includes POD's application within a FE-LES turbulence model that uses adaptive resolution. The accuracy of the reduced order model is assessed and validated for a range of 2D and 3D urban street canyon flow problems. By comparing the POD solutions against the fine detail solutions obtained from the full FE model it is shown that the accuracy is maintained, where fine details of the air flows are captured, whilst the computational requirements are reduced. In the examples presented below the size of the reduced order models is reduced by factors up to 2400 in comparison to the full FE model while the CPU time is reduced by up to 98% of that required by the full model.
Finite-element mesh generation from mappable features
Kuniansky, Eve L.; Lowther, Robert A.
1993-01-01
A vector-based geographical information system (GIS) is used to generate a variably-sized triangular element finite-element mesh from mappable features. Important digitally-mapped features are automatically linked to nodes in the finite-element model, ensuring an efficient, virtually error-free alternative to the tedious process of mesh design and data-input preparation by other methods. The procedure permits the user to work interactively with graphically-displayed hydrologic information about the study area allowing different mesh sizes to be used as needed, based on hydrologic complexity. The mesh-generaiion programs are stand-alone macros within the GIS that set up the basic data defining a finite-element mesh for many different finite-element model programs.
Numerical interactive grid generation for 3-D flow calculations
NASA Astrophysics Data System (ADS)
Jacobs, J. M. J. W.; Kassies, A.; Boerstoel, J. W.; Buijsen, F.; Kuijvenhoven, J. L.
1988-08-01
A method for the generation of three-dimensional block-structured grids is described. The grid generation process is decomposed into two major stages: block decomposition of the flow domain and construction of a grid in each block. Examples of grids are shown together with flow solver results. Improvements and future extensions of the present concepts are discussed.
Generation of Delaunay meshes in implicit domains with edge sharpening
NASA Astrophysics Data System (ADS)
Belokrys-Fedotov, A. I.; Garanzha, V. A.; Kudryavtseva, L. N.
2016-11-01
A variational algorithm for the construction of 3D Delaunay meshes in implicit domains with a nonsmooth boundary is proposed. The algorithm is based on the self-organization of an elastic network in which each Delaunay edge is interpreted as an elastic strut. The elastic potential is constructed as a combination of the repulsion potential and the sharpening potential. The sharpening potential is applied only on the boundary and is used to minimize the deviation of the outward normals to the boundary faces from the direction of the gradient of the implicit function. Numerical experiments showed that in the case when the implicit function specifying the domain is considerably different from the signed distance function, the use of the sharpening potential proposed by Belyaev and Ohtake in 2002 leads to the mesh instability. A stable version of the sharpening potential is proposed. The numerical experiments showed that acceptable Delaunay meshes for complex shaped domains with sharp curved boundary edges can be constructed.
Bland, M; Wondra, J; Nunan, S; Walters, D
1998-12-01
A graphical user interface (GUI) is under development for the MEEC family of SGEMP and SREMP simulation codes. These codes are workhorse legacy codes that have been in use for nearly two decades, with modifications and enhanced physics models added throughout the years. The MEEC codes are currently being evaluated for use by the DOE in the Dual Revalidation program and experiments at NIF. The new GUI makes the codes more accessible and less prone to input errors by automatically generating the parameters and grids that previously had to be designed by hand. physics-based algorithms define the simulation volume with expanding meshes. Users are able to specify objects, materials, and emission surfaces through dialogs and input boxes. 3D and orthographic views are available to view objects in the volume. Zone slice views are available for stepping through the overlay of objects on the mesh in planes aligned with the primary axes.
Bland, M; Walters, D; Wondra, J
1999-06-01
A graphical user interface (GUI) is under development for the MEEC family of SGEMP and SREMP simulation codes [1,2]. These codes are ''workhorse'' legacy codes that have been in use for nearly two decades, with modifications and enhanced physics models added throughout the years. The MEEC codes are currently being evaluated for use by the DOE in the Dual Revalidation Program and experiments at NIF. The new GUI makes the codes more accessible and less prone to input errors by automatically generating the parameters and grids that previously had to be designed ''by hand''. Physics-based algorithms define the simulation volume with expanding meshes. Users are able to specify objects, materials, and emission surfaces through dialogs and input boxes. 3D and orthographic views are available to view objects in the volume. Zone slice views are available for stepping through the overlay of objects on the mesh in planes aligned with the primary axes.
2011-01-01
A 63 year-old male with a huge odontogenic lesion of sinus maxillaris was treated with computer-assisted surgery. After resection of the odontogenic lesion, the sinus wall was reconstructed with a prebended 3D titanium-mesh using CAD/CAM technique. This work provides a new treatment device for maxillary reconstruction via rapid prototyping procedures. PMID:22070833
Extraction and applications of skeletons in finite element mesh generation.
Quadros, William Roshan
2010-05-01
This paper focuses on the extraction of skeletons of CAD models and its applications in finite element (FE) mesh generation. The term 'skeleton of a CAD model' can be visualized as analogous to the 'skeleton of a human body'. The skeletal representations covered in this paper include medial axis transform (MAT), Voronoi diagram (VD), chordal axis transform (CAT), mid surface, digital skeletons, and disconnected skeletons. In the literature, the properties of a skeleton have been utilized in developing various algorithms for extracting skeletons. Three main approaches include: (1) the bisection method where the skeleton exists at equidistant from at least two points on boundary, (2) the grassfire propagation method in which the skeleton exists where the opposing fronts meet, and (3) the duality method where the skeleton is a dual of the object. In the last decade, the author has applied different skeletal representations in all-quad meshing, hex meshing, mid-surface meshing, mesh size function generation, defeaturing, and decomposition. A brief discussion on the related work from other researchers in the area of tri meshing, tet meshing, and anisotropic meshing is also included. This paper concludes by summarizing the strengths and weaknesses of the skeleton-based approaches in solving various geometry-centered problems in FE mesh generation. The skeletons have proved to be a great shape abstraction tool in analyzing the geometric complexity of CAD models as they are symmetric, simpler (reduced dimension), and provide local thickness information. However, skeletons generally require some cleanup, and stability and sensitivity of the skeletons should be controlled during extraction. Also, selecting a suitable application-specific skeleton and a computationally efficient method of extraction is critical.
Numerical grid generation in 3D Euler-flow simulation
NASA Astrophysics Data System (ADS)
Boerstoel, J. W.
1988-04-01
The technical problems with grid generation are analyzed and an overview of proposed solutions is given. The usefulness of grid-generation techniques, for the numerical simulation of Euler (and Navier-Stokes) flows around complex three-dimensional aerodynamic configurations, is illustrated. It is shown that the core of the grid-generation problem is a topology problem. The following remarks are sketched: grid generation is a subtask in a numerical simulation of a flow in industrial and research environments; the design requirements of a grid generation concern the geometrical imput, the desired grid as output, the technical means to control grid resolution and quality and turnaround time performance; the construction of a blocked grid can be subdivided in a block-decomposition task and a grid-point distribution task. A technique for using connectivity relations to define conventions about local coordinate systems in edges, faces and blocks is presented. Experiences are reported and an example concerning a 96-blocked grid around a complex aerodynamic configuration is given. Concepts for improvements in the presented technique are discussed.
Fast Generation of body conforming grids for 3-D
NASA Technical Reports Server (NTRS)
Dulikravich, O.
1980-01-01
A fast algorithm was developed for accurately generating boundary conforming, three dimensional, consecutively refined, computational grids applicable to arbitrary axial turbomachinery geometry. The method is based on using a single analytic function to generate two dimensional grids on a number of coaxial axisymmetric surfaces positioned between the hub and the shroud. These grids are of the "O" type and are characterized by quasi-orthogonality, geometric periodicity, and an adequate resolution throughout the flowfield. Due to the built in additional nonorthogonal coordinate stretching and shearing, the grid lines leaving the trailing of the blade end at downstream infinity, thus simplifying the numerical treatment of the three dimensional trailing vortex sheet.
PREDICTING TSUNAMIS GENERATED BY 3D GRANULAR LANDSLIDES
NASA Astrophysics Data System (ADS)
Mohammed, F.; Fritz, H. M.
2009-12-01
Landslides can trigger tsunamis with locally high amplitudes and runup, which can cause devastating effects in the near field region such as at Lituya Bay (1958), Papua New Guinea (1998) and Java (2006). Tsunamis generated by granular landslides were studied in the three dimensional NEES tsunami wave basin (TWB) at Oregon State University (OSU) based on the generalized Froude similarity. A novel pneumatic landslide generator was deployed to simulate deformable granular landslides with varying geometry and kinematics. Measurement techniques such as particle image velocimetry (PIV), multiple above and underwater video cameras, multiple acoustic transducer arrays (MTA), as well as resistance wave and runup gauges were applied. The wave generation was characterized by an extremely unsteady three phase flow consisting of the slide granulate, water and air entrained into the flow. The landslide deformation during the impact and the subsequent underwater motion was studied by underwater cameras while the MTA provided the shapes of the slide deposits on the basin bottom. The generated waves depend on determined non-dimensional landslide and water body parameters such as the slide Froude number and relative slide shape at impact, among others. The experimental data was used to obtain predictive equations for the wave amplitudes and time periods based on landslide characteristics at impact. The partition between wave crests and troughs departed from equipartition with wave profiles dominated either by a trough or a crest depending on the source. Attenuation functions of the leading wave crest amplitude, the lateral wave runup on the hill slope, the wave length and the time period were obtained to describe the wave behavior in the near field and to quantify the wave amplitude decay away from the landslide source. The measured wave celerity of the leading wave corresponds well to the theoretical approximation of the solitary wave speed while the trailing waves are considerably
Characteristics of tsunamis generated by 3D deformable granular landslides
NASA Astrophysics Data System (ADS)
Mohammed, F.; Fritz, H. M.; McFall, B.
2010-12-01
Landslides can trigger tsunamis with locally high amplitudes and runup, which can cause devastating effects in the near field region. The events of 1958 Lituya Bay, 1998 Papua New Guinea and 2006 Java tsunamis are reminders of the hazards associated with impulse waves. Tsunamis generated by granular landslides were studied in the three dimensional NEES tsunami wave basin (TWB) at Oregon State University (OSU) based on the generalized Froude similarity. A novel pneumatic landslide generator was deployed to simulate landslides with varying geometry and kinematics. Granular materials were used to model deformable landslides. Measurement techniques such as particle image velocimetry (PIV), multiple above and underwater video cameras, multiple acoustic transducer arrays (MTA), as well as resistance wave and runup gauges were applied. Tsunami wave generation and propagation is studied off a hill slope, in fjords and around curved headlands. The wave generation was characterized by an extremely unsteady three phase flow consisting of the slide granulate, water and air entrained into the flow. Landslide deformation is quantified and the slide kinematics with reference to slide surface velocity distribution and slide front velocity is obtained. Empirical equations for predicting the wave amplitude, period and wavelength are obtained. The generated waves depend on determined non-dimensional landslide and water body parameters such as the slide Froude number and relative slide shape at impact, among others. Attenuation functions of the leading wave crest amplitude, the lateral wave runup on the hill slope, the wave length and the time period were obtained to describe the wave behavior in the near field and to quantify the wave amplitude decay away from the landslide source. The measured wave celerity of the leading wave corresponds well to the solitary wave speed while the trailing waves are considerably slower in propagation. The individual waves in the wave train span from
Mesh Generation via Local Bisection Refinement of Triangulated Grids
2015-06-01
bucketing techniques in computational geometry, in Computational Geometry, Vol. 2 of Machine Intelligence and Pattern Recognition , Elsevier, North Holland...UNCLASSIFIED Mesh Generation via Local Bisection Refinement of Triangulated Grids Jason R. Looker Joint and Operations Analysis Division Defence...triangles. The mesh refinement algorithm is tested and shown to achieve the anticipated linear running time with respect to the number of triangles in the
Three dimensional mesh generation by triangulation of arbitrary point sets
NASA Technical Reports Server (NTRS)
Baker, Timothy J.
1987-01-01
A method for generating an unstructured mesh is described. The approach is quite general and joins an arbitrary set of points to produce a covering of three dimensional space by tetrahedra. After removing the tetrahedra that connect surface points, a mesh suitable for a finite element based flow solver is obtained. Details of the triangulation algorithm are provided together with an analysis of the algorithm efficiency and validity.
3D automatic Cartesian grid generation for Euler flows
NASA Technical Reports Server (NTRS)
Melton, John E.; Enomoto, Francis Y.; Berger, Marsha J.
1993-01-01
We describe a Cartesian grid strategy for the study of three dimensional inviscid flows about arbitrary geometries that uses both conventional and CAD/CAM surface geometry databases. Initial applications of the technique are presented. The elimination of the body-fitted constraint allows the grid generation process to be automated, significantly reducing the time and effort required to develop suitable computational grids for inviscid flowfield simulations.
3D automatic Cartesian grid generation for Euler flows
NASA Technical Reports Server (NTRS)
Melton, John E.; Enomoto, Francis Y.; Berger, Marsha J.
1993-01-01
We describe a Cartesian grid strategy for the study of three dimensional inviscid flows about arbitrary geometries that uses both conventional and CAD/CAM surface geometry databases. Initial applications of the technique are presented. The elimination of the body-fitted constraint allows the grid generation process to be automated, significantly reducing the time and effort required to develop suitable computational grids for inviscid flowfield simulations.
Computer generated holograms from three dimensional meshes using an analytic light transport model
NASA Astrophysics Data System (ADS)
Ahrenberg, Lukas; Benzie, Philip; Magnor, Marcus; Watson, John
2008-04-01
We present a method to analytically compute the light distribution of triangles directly in frequency space. This allows for fast evaluation, shading, and propagation of light from 3D mesh objects using angular spectrum methods. The algorithm complexity is only dependent on the hologram resolution and the polygon count of the 3D model. In contrast to other polygon based computer generated holography methods we do not need to perform a Fourier transform per surface. The theory behind the approach is derived, and a suitable algorithm to compute a digital hologram from a general triangle mesh is presented. We review some first results rendered on a spatial-light-modulator-based display by our proof-of-concept software.
Computer generated holograms from three dimensional meshes using an analytic light transport model.
Ahrenberg, Lukas; Benzie, Philip; Magnor, Marcus; Watson, John
2008-04-01
We present a method to analytically compute the light distribution of triangles directly in frequency space. This allows for fast evaluation, shading, and propagation of light from 3D mesh objects using angular spectrum methods. The algorithm complexity is only dependent on the hologram resolution and the polygon count of the 3D model. In contrast to other polygon based computer generated holography methods we do not need to perform a Fourier transform per surface. The theory behind the approach is derived, and a suitable algorithm to compute a digital hologram from a general triangle mesh is presented. We review some first results rendered on a spatial-light-modulator-based display by our proof-of-concept software.
Georeferenced LiDAR 3D Vine Plantation Map Generation
Llorens, Jordi; Gil, Emilio; Llop, Jordi; Queraltó, Meritxell
2011-01-01
The use of electronic devices for canopy characterization has recently been widely discussed. Among such devices, LiDAR sensors appear to be the most accurate and precise. Information obtained with LiDAR sensors during reading while driving a tractor along a crop row can be managed and transformed into canopy density maps by evaluating the frequency of LiDAR returns. This paper describes a proposed methodology to obtain a georeferenced canopy map by combining the information obtained with LiDAR with that generated using a GPS receiver installed on top of a tractor. Data regarding the velocity of LiDAR measurements and UTM coordinates of each measured point on the canopy were obtained by applying the proposed transformation process. The process allows overlap of the canopy density map generated with the image of the intended measured area using Google Earth®, providing accurate information about the canopy distribution and/or location of damage along the rows. This methodology was applied and tested on different vine varieties and crop stages in two important vine production areas in Spain. The results indicate that the georeferenced information obtained with LiDAR sensors appears to be an interesting tool with the potential to improve crop management processes. PMID:22163952
Georeferenced LiDAR 3D vine plantation map generation.
Llorens, Jordi; Gil, Emilio; Llop, Jordi; Queraltó, Meritxell
2011-01-01
The use of electronic devices for canopy characterization has recently been widely discussed. Among such devices, LiDAR sensors appear to be the most accurate and precise. Information obtained with LiDAR sensors during reading while driving a tractor along a crop row can be managed and transformed into canopy density maps by evaluating the frequency of LiDAR returns. This paper describes a proposed methodology to obtain a georeferenced canopy map by combining the information obtained with LiDAR with that generated using a GPS receiver installed on top of a tractor. Data regarding the velocity of LiDAR measurements and UTM coordinates of each measured point on the canopy were obtained by applying the proposed transformation process. The process allows overlap of the canopy density map generated with the image of the intended measured area using Google Earth(®), providing accurate information about the canopy distribution and/or location of damage along the rows. This methodology was applied and tested on different vine varieties and crop stages in two important vine production areas in Spain. The results indicate that the georeferenced information obtained with LiDAR sensors appears to be an interesting tool with the potential to improve crop management processes.
A simple and low-cost 3d-printed emulsion generator
NASA Astrophysics Data System (ADS)
Zhang, J. M.; Aguirre-Pablo, A. A.; Li, E. Q.; Thoroddsen, S. T.
2015-11-01
The technique traditionally utilized to fabricate microfluidic emulsion generators, i.e. soft-lithography, is complex and expensive for producing three-dimensional (3D) structures. Here we apply 3D printing technology to fabricate a simple and low-cost 3D printed microfluidic device for emulsion generation without the need for surface treatment on the channel walls. This 3D-printed emulsion generator has been successfully tested over a range of conditions. We also formulate and demonstrate uniform scaling laws for emulsion droplets generated in different regimes for the first time, by incorporating the dynamic contact angle effects during the drop formation. Magnetically responsive microspheres are also produced with our emulsion templates, demonstrating the potential applications of this 3D emulsion generator in material and chemical engineering.
The role of the cytoskeleton in cellular force generation in 2D and 3D environments
NASA Astrophysics Data System (ADS)
Kraning-Rush, Casey M.; Carey, Shawn P.; Califano, Joseph P.; Smith, Brooke N.; Reinhart-King, Cynthia A.
2011-02-01
To adhere and migrate, cells generate forces through the cytoskeleton that are transmitted to the surrounding matrix. While cellular force generation has been studied on 2D substrates, less is known about cytoskeletal-mediated traction forces of cells embedded in more in vivo-like 3D matrices. Recent studies have revealed important differences between the cytoskeletal structure, adhesion, and migration of cells in 2D and 3D. Because the cytoskeleton mediates force, we sought to directly compare the role of the cytoskeleton in modulating cell force in 2D and 3D. MDA-MB-231 cells were treated with agents that perturbed actin, microtubules, or myosin, and analyzed for changes in cytoskeletal organization and force generation in both 2D and 3D. To quantify traction stresses in 2D, traction force microscopy was used; in 3D, force was assessed based on single cell-mediated collagen fibril reorganization imaged using confocal reflectance microscopy. Interestingly, even though previous studies have observed differences in cell behaviors like migration in 2D and 3D, our data indicate that forces generated on 2D substrates correlate with forces within 3D matrices. Disruption of actin, myosin or microtubules in either 2D or 3D microenvironments disrupts cell-generated force. These data suggest that despite differences in cytoskeletal organization in 2D and 3D, actin, microtubules and myosin contribute to contractility and matrix reorganization similarly in both microenvironments.
Feature based volume decomposition for automatic hexahedral mesh generation
LU,YONG; GADH,RAJIT; TAUTGES,TIMOTHY J.
2000-02-21
Much progress has been made through these years to achieve automatic hexahedral mesh generation. While general meshing algorithms that can take on general geometry are not there yet; many well-proven automatic meshing algorithms now work on certain classes of geometry. This paper presents a feature based volume decomposition approach for automatic Hexahedral Mesh generation. In this approach, feature recognition techniques are introduced to determine decomposition features from a CAD model. The features are then decomposed and mapped with appropriate automatic meshing algorithms suitable for the correspondent geometry. Thus a formerly unmeshable CAD model may become meshable. The procedure of feature decomposition is recursive: sub-models are further decomposed until either they are matched with appropriate meshing algorithms or no more decomposition features are detected. The feature recognition methods employed are convexity based and use topology and geometry information, which is generally available in BREP solid models. The operations of volume decomposition are also detailed in the paper. The final section, the capability of the feature decomposer is demonstrated over some complicated manufactured parts.
Automated Mosaicking of Multiple 3d Point Clouds Generated from a Depth Camera
NASA Astrophysics Data System (ADS)
Kim, H.; Yoon, W.; Kim, T.
2016-06-01
In this paper, we propose a method for automated mosaicking of multiple 3D point clouds generated from a depth camera. A depth camera generates depth data by using ToF (Time of Flight) method and intensity data by using intensity of returned signal. The depth camera used in this paper was a SR4000 from MESA Imaging. This camera generates a depth map and intensity map of 176 x 44 pixels. Generated depth map saves physical depth data with mm of precision. Generated intensity map contains texture data with many noises. We used texture maps for extracting tiepoints and depth maps for assigning z coordinates to tiepoints and point cloud mosaicking. There are four steps in the proposed mosaicking method. In the first step, we acquired multiple 3D point clouds by rotating depth camera and capturing data per rotation. In the second step, we estimated 3D-3D transformation relationships between subsequent point clouds. For this, 2D tiepoints were extracted automatically from the corresponding two intensity maps. They were converted into 3D tiepoints using depth maps. We used a 3D similarity transformation model for estimating the 3D-3D transformation relationships. In the third step, we converted local 3D-3D transformations into a global transformation for all point clouds with respect to a reference one. In the last step, the extent of single depth map mosaic was calculated and depth values per mosaic pixel were determined by a ray tracing method. For experiments, 8 depth maps and intensity maps were used. After the four steps, an output mosaicked depth map of 454x144 was generated. It is expected that the proposed method would be useful for developing an effective 3D indoor mapping method in future.
Generation of flat viewing zone in DFVZ autostereoscopic multiview 3D display by weighting factor
NASA Astrophysics Data System (ADS)
Kim, Sung-Kyu; Yoon, Seon-Kyu; Yoon, Ky-Hyuk
2013-05-01
A new method is introduced to reduce three crosstalk problems and the brightness variation in 3D image by means of the dynamic fusion of viewing zones (DFVZ) using weighting factor. The new method effectively generates the flat viewing zone at the center of viewing zone. The new type autostereoscopic 3D display can give less brightness variation of 3D image when observer moves.
Rapid mesh generation for finite element analysis of investment castings
Lober, R.R.; Bohnhoff, W.J.; Meyers, R.J.
1992-11-01
FASTCAST is a Sandia National Laboratories program to produce investment cast prototypical hardware faster by integrating experimental and computational technologies into the casting process. FASTCAST uses the finite element method to characterize the metal flow and solidification processes to reduce uncertainty in the mold design. For the casting process to benefit from finite element analysis, analysis results must be available in a very short time frame. By focusing on the bottleneck of finite element model creation, automated mesh generation can drastically reduce the time span between geometry definition (design) and accurate analysis results. The increased availability of analysis results will diminish the need for trial and error approaches to acquiring production worthy mold and gating systems for investment casting. The CUBIT meshing tool kit is being developed to address the need for rapid mesh generation. CUBIT is being designed to effectively automate the generation of quadrilateral and hexahedral elements. It is a solid-modeler based, two- and three-dimensional preprocessor that prepares solid models for finite element analysis. CUBIT contains several meshing algorithms including two- and three-dimensional mapping, two- and three-dimensional paving (patented), and a general two and one-half dimensional sweeper based upon the plastering algorithm. This paper describes progress in the development of the CUBIT meshing toolkit.
Rapid mesh generation for finite element analysis of investment castings
Lober, R.R.; Bohnhoff, W.J.; Meyers, R.J.
1992-01-01
FASTCAST is a Sandia National Laboratories program to produce investment cast prototypical hardware faster by integrating experimental and computational technologies into the casting process. FASTCAST uses the finite element method to characterize the metal flow and solidification processes to reduce uncertainty in the mold design. For the casting process to benefit from finite element analysis, analysis results must be available in a very short time frame. By focusing on the bottleneck of finite element model creation, automated mesh generation can drastically reduce the time span between geometry definition (design) and accurate analysis results. The increased availability of analysis results will diminish the need for trial and error approaches to acquiring production worthy mold and gating systems for investment casting. The CUBIT meshing tool kit is being developed to address the need for rapid mesh generation. CUBIT is being designed to effectively automate the generation of quadrilateral and hexahedral elements. It is a solid-modeler based, two- and three-dimensional preprocessor that prepares solid models for finite element analysis. CUBIT contains several meshing algorithms including two- and three-dimensional mapping, two- and three-dimensional paving (patented), and a general two and one-half dimensional sweeper based upon the plastering algorithm. This paper describes progress in the development of the CUBIT meshing toolkit.
Customised 3D Printing: An Innovative Training Tool for the Next Generation of Orbital Surgeons.
Scawn, Richard L; Foster, Alex; Lee, Bradford W; Kikkawa, Don O; Korn, Bobby S
2015-01-01
Additive manufacturing or 3D printing is the process by which three dimensional data fields are translated into real-life physical representations. 3D printers create physical printouts using heated plastics in a layered fashion resulting in a three-dimensional object. We present a technique for creating customised, inexpensive 3D orbit models for use in orbital surgical training using 3D printing technology. These models allow trainee surgeons to perform 'wet-lab' orbital decompressions and simulate upcoming surgeries on orbital models that replicate a patient's bony anatomy. We believe this represents an innovative training tool for the next generation of orbital surgeons.
Dry particle generation with a 3-D printed fluidized bed generator
Roesch, Michael; Roesch, Carolin; Cziczo, Daniel J.
2017-06-02
We describe the design and testing of PRIZE (PRinted fluidIZed bed gEnerator), a compact fluidized bed aerosol generator manufactured using stereolithography (SLA) printing. Dispersing small quantities of powdered materials – due to either rarity or expense – is challenging due to a lack of small, low-cost dry aerosol generators. With this as motivation, we designed and built a generator that uses a mineral dust or other dry powder sample mixed with bronze beads that sit atop a porous screen. A particle-free airflow is introduced, dispersing the sample as airborne particles. The total particle number concentrations and size distributions were measured duringmore » different stages of the assembling process to show that the SLA 3-D printed generator did not generate particles until the mineral dust sample was introduced. Furthermore, time-series measurements with Arizona Test Dust (ATD) showed stable total particle number concentrations of 10–150 cm-3, depending on the sample mass, from the sub- to super-micrometer size range. Additional tests with collected soil dust samples are also presented. PRIZE is simple to assemble, easy to clean, inexpensive and deployable for laboratory and field studies that require dry particle generation.« less
Dry particle generation with a 3-D printed fluidized bed generator
NASA Astrophysics Data System (ADS)
Roesch, Michael; Roesch, Carolin; Cziczo, Daniel J.
2017-06-01
Here we describe the design and testing of PRIZE (PRinted fluidIZed bed gEnerator), a compact fluidized bed aerosol generator manufactured using stereolithography (SLA) printing. Dispersing small quantities of powdered materials - due to either rarity or expense - is challenging due to a lack of small, low-cost dry aerosol generators. With this as motivation, we designed and built a generator that uses a mineral dust or other dry powder sample mixed with bronze beads that sit atop a porous screen. A particle-free airflow is introduced, dispersing the sample as airborne particles. Total particle number concentrations and size distributions were measured during different stages of the assembling process to show that the SLA 3-D printed generator did not generate particles until the mineral dust sample was introduced. Time-series measurements with Arizona Test Dust (ATD) showed stable total particle number concentrations of 10-150 cm-3, depending on the sample mass, from the sub- to super-micrometer size range. Additional tests with collected soil dust samples are also presented. PRIZE is simple to assemble, easy to clean, inexpensive and deployable for laboratory and field studies that require dry particle generation.
Manual for automatic generation of finite element models of spiral bevel gears in mesh
NASA Technical Reports Server (NTRS)
Bibel, G. D.; Reddy, S.; Kumar, A.
1994-01-01
The goal of this research is to develop computer programs that generate finite element models suitable for doing 3D contact analysis of faced milled spiral bevel gears in mesh. A pinion tooth and a gear tooth are created and put in mesh. There are two programs: Points.f and Pat.f to perform the analysis. Points.f is based on the equation of meshing for spiral bevel gears. It uses machine tool settings to solve for an N x M mesh of points on the four surfaces, pinion concave and convex, and gear concave and convex. Points.f creates the file POINTS.OUT, an ASCI file containing N x M points for each surface. (N is the number of node points along the length of the tooth, and M is nodes along the height.) Pat.f reads POINTS.OUT and creates the file tl.out. Tl.out is a series of PATRAN input commands. In addition to the mesh density on the tooth face, additional user specified variables are the number of finite elements through the thickness, and the number of finite elements along the tooth full fillet. A full fillet is assumed to exist for both the pinion and gear.
Loft: An Automated Mesh Generator for Stiffened Shell Aerospace Vehicles
NASA Technical Reports Server (NTRS)
Eldred, Lloyd B.
2011-01-01
Loft is an automated mesh generation code that is designed for aerospace vehicle structures. From user input, Loft generates meshes for wings, noses, tanks, fuselage sections, thrust structures, and so on. As a mesh is generated, each element is assigned properties to mark the part of the vehicle with which it is associated. This property assignment is an extremely powerful feature that enables detailed analysis tasks, such as load application and structural sizing. This report is presented in two parts. The first part is an overview of the code and its applications. The modeling approach that was used to create the finite element meshes is described. Several applications of the code are demonstrated, including a Next Generation Launch Technology (NGLT) wing-sizing study, a lunar lander stage study, a launch vehicle shroud shape study, and a two-stage-to-orbit (TSTO) orbiter. Part two of the report is the program user manual. The manual includes in-depth tutorials and a complete command reference.
Generating unstructured nuclear reactor core meshes in parallel
Jain, Rajeev; Tautges, Timothy J.
2014-10-24
Recent advances in supercomputers and parallel solver techniques have enabled users to run large simulations problems using millions of processors. Techniques for multiphysics nuclear reactor core simulations are under active development in several countries. Most of these techniques require large unstructured meshes that can be hard to generate in a standalone desktop computers because of high memory requirements, limited processing power, and other complexities. We have previously reported on a hierarchical lattice-based approach for generating reactor core meshes. Here, we describe efforts to exploit coarse-grained parallelism during reactor assembly and reactor core mesh generation processes. We highlight several reactor coremore » examples including a very high temperature reactor, a full-core model of the Korean MONJU reactor, a ¼ pressurized water reactor core, the fast reactor Experimental Breeder Reactor-II core with a XX09 assembly, and an advanced breeder test reactor core. The times required to generate large mesh models, along with speedups obtained from running these problems in parallel, are reported. A graphical user interface to the tools described here has also been developed.« less
Generating unstructured nuclear reactor core meshes in parallel
Jain, Rajeev; Tautges, Timothy J.
2014-10-24
Recent advances in supercomputers and parallel solver techniques have enabled users to run large simulations problems using millions of processors. Techniques for multiphysics nuclear reactor core simulations are under active development in several countries. Most of these techniques require large unstructured meshes that can be hard to generate in a standalone desktop computers because of high memory requirements, limited processing power, and other complexities. We have previously reported on a hierarchical lattice-based approach for generating reactor core meshes. Here, we describe efforts to exploit coarse-grained parallelism during reactor assembly and reactor core mesh generation processes. We highlight several reactor core examples including a very high temperature reactor, a full-core model of the Korean MONJU reactor, a ¼ pressurized water reactor core, the fast reactor Experimental Breeder Reactor-II core with a XX09 assembly, and an advanced breeder test reactor core. The times required to generate large mesh models, along with speedups obtained from running these problems in parallel, are reported. A graphical user interface to the tools described here has also been developed.
Fantino, Erika; Chiappone, Annalisa; Roppolo, Ignazio; Manfredi, Diego; Bongiovanni, Roberta; Pirri, Candido Fabrizio; Calignano, Flaviana
2016-05-01
On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures by coupling the photo-reduction of metal precursors with 3D printing technology. The generated structures consist of metal nanoparticles embedded in a polymer matrix shaped into complex multilayered architectures. 3D conductive structures are fabricated with a digital light-processing printer incorporating silver salt into photocurable formulations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Approaches to the automatic generation and control of finite element meshes
NASA Technical Reports Server (NTRS)
Shephard, Mark S.
1987-01-01
The algorithmic approaches being taken to the development of finite element mesh generators capable of automatically discretizing general domains without the need for user intervention are discussed. It is demonstrated that because of the modeling demands placed on a automatic mesh generator, all the approaches taken to date produce unstructured meshes. Consideration is also given to both a priori and a posteriori mesh control devices for automatic mesh generators as well as their integration with geometric modeling and adaptive analysis procedures.
NASA Astrophysics Data System (ADS)
Prashanth, B. N.; Roy, Kingshuk
2017-07-01
Three Dimensional (3D) maintenance data provides a link between design and technical documentation creating interactive 3D graphical training and maintenance material. It becomes difficult for an operator to always go through huge paper manuals or come running to the computer for doing maintenance of a machine which makes the maintenance work fatigue. Above being the case, a 3D animation makes maintenance work very simple since, there is no language barrier. The research deals with the generation of 3D maintenance data of any given machine. The best tool for obtaining the 3D maintenance is selected and the tool is analyzed. Using the same tool, a detailed process for extracting the 3D maintenance data for any machine is set. This project aims at selecting the best tool for obtaining 3D maintenance data and to select the detailed process for obtaining 3D maintenance data. 3D maintenance reduces use of big volumes of manuals which creates human errors and makes the work of an operator fatiguing. Hence 3-D maintenance would help in training and maintenance and would increase productivity. 3Dvia when compared with Cortona 3D and Deep Exploration proves to be better than them. 3Dvia is good in data translation and it has the best renderings compared to the other two 3D maintenance software. 3Dvia is very user friendly and it has various options for creating 3D animations. Its Interactive Electronic Technical Publication (IETP) integration is also better than the other two software. Hence 3Dvia proves to be the best software for obtaining 3D maintenance data of any machine.
NASA Technical Reports Server (NTRS)
Marvriplis, D. J.; Venkatakrishnan, V.
1995-01-01
An agglomeration multigrid strategy is developed and implemented for the solution of three-dimensional steady viscous flows. The method enables convergence acceleration with minimal additional memory overheads, and is completely automated, in that it can deal with grids of arbitrary construction. The multigrid technique is validated by comparing the delivered convergence rates with those obtained by a previously developed overset-mesh multigrid approach, and by demonstrating grid independent convergence rates for aerodynamic problems on very large grids. Prospects for further increases in multigrid efficiency for high-Reynolds number viscous flows on highly stretched meshes are discussed.
A finite-element mesh generator based on growing neural networks.
Triantafyllidis, D G; Labridis, D P
2002-01-01
A mesh generator for the production of high-quality finite-element meshes is being proposed. The mesh generator uses an artificial neural network, which grows during the training process in order to adapt itself to a prespecified probability distribution. The initial mesh is a constrained Delaunay triangulation of the domain to be triangulated. Two new algorithms to accelerate the location of the best matching unit are introduced. The mesh generator has been found able to produce meshes of high quality in a number of classic cases examined and is highly suited for problems where the mesh density vector can be calculated in advance.
Efficient generation of 3D hologram for American Sign Language using look-up table
NASA Astrophysics Data System (ADS)
Park, Joo-Sup; Kim, Seung-Cheol; Kim, Eun-Soo
2010-02-01
American Sign Language (ASL) is one of the languages giving the greatest help for communication of the hearing impaired person. Current 2-D broadcasting, 2-D movies are used the ASL to give some information, help understand the situation of the scene and translate the foreign language. These ASL will not be disappeared in future three-dimensional (3-D) broadcasting or 3-D movies because the usefulness of the ASL. On the other hands, some approaches for generation of CGH patterns have been suggested like the ray-tracing method and look-up table (LUT) method. However, these methods have some drawbacks that needs much time or needs huge memory size for look-up table. Recently, a novel LUT (N-LUT) method for fast generation of CGH patterns of 3-D objects with a dramatically reduced LUT without the loss of computational speed was proposed. Therefore, we proposed the method to efficiently generate the holographic ASL in holographic 3DTV or 3-D movies using look-up table method. The proposed method is largely consisted of five steps: construction of the LUT for each ASL images, extraction of characters in scripts or situation, call the fringe patterns for characters in the LUT for each ASL, composition of hologram pattern for 3-D video and hologram pattern for ASL and reconstruct the holographic 3D video with ASL. Some simulation results confirmed the feasibility of the proposed method in efficient generation of CGH patterns for ASL.
NASA Astrophysics Data System (ADS)
Huang, Sujuan; Wang, Duocheng; He, Chao
2012-11-01
A new method of synthesizing computer-generated hologram of three-dimensional (3D) objects is proposed from their projection images. A series of projection images of 3D objects are recorded with one-dimensional azimuth scanning. According to the principles of paraboloid of revolution in 3D Fourier space and 3D central slice theorem, spectra information of 3D objects can be gathered from their projection images. Considering quantization error of horizontal and vertical directions, the spectrum information from each projection image is efficiently extracted in double circle and four circles shape, to enhance the utilization of projection spectra. Then spectra information of 3D objects from all projection images is encoded into computer-generated hologram based on Fourier transform using conjugate-symmetric extension. The hologram includes 3D information of objects. Experimental results for numerical reconstruction of the CGH at different distance validate the proposed methods and show its good performance. Electro-holographic reconstruction can be realized by using an electronic addressing reflective liquid-crystal display (LCD) spatial light modulator. The CGH from the computer is loaded onto the LCD. By illuminating a reference light from a laser source to the LCD, the amplitude and phase information included in the CGH will be reconstructed due to the diffraction of the light modulated by the LCD.
In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures.
Fantino, Erika; Chiappone, Annalisa; Calignano, Flaviana; Fontana, Marco; Pirri, Fabrizio; Roppolo, Ignazio
2016-07-19
Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP) system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs) in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites.
In Situ Thermal Generation of Silver Nanoparticles in 3D Printed Polymeric Structures
Fantino, Erika; Chiappone, Annalisa; Calignano, Flaviana; Fontana, Marco; Pirri, Fabrizio; Roppolo, Ignazio
2016-01-01
Polymer nanocomposites have always attracted the interest of researchers and industry because of their potential combination of properties from both the nanofillers and the hosting matrix. Gathering nanomaterials and 3D printing could offer clear advantages and numerous new opportunities in several application fields. Embedding nanofillers in a polymeric matrix could improve the final material properties but usually the printing process gets more difficult. Considering this drawback, in this paper we propose a method to obtain polymer nanocomposites by in situ generation of nanoparticles after the printing process. 3D structures were fabricated through a Digital Light Processing (DLP) system by disolving metal salts in the starting liquid formulation. The 3D fabrication is followed by a thermal treatment in order to induce in situ generation of metal nanoparticles (NPs) in the polymer matrix. Comprehensive studies were systematically performed on the thermo-mechanical characteristics, morphology and electrical properties of the 3D printed nanocomposites. PMID:28773716
RESTRUCTURING RELAP5-3D FOR NEXT GENERATION NUCLEAR PLANT ANALYSIS
Donna Post Guillen; George L. Mesina; Joshua M. Hykes
2006-06-01
RELAP5-3D is used worldwide for analyzing nuclear reactors under both operational transients and postulated accident conditions. Development of the RELAP code series began in 1975 and since that time the code has been continuously improved, enhanced, verified and validated [1]. Since RELAP5-3D will continue to be the premier thermal hydraulics tool well into the future, it is necessary to modernize the code to accommodate the incorporation of additional capabilities to support the development of the next generation of nuclear reactors [2]. This paper discusses the reengineering of RELAP5-3D into structured code.
NASA Astrophysics Data System (ADS)
Delandmeter, Philippe; Lambrechts, Jonathan; Vallaeys, Valentin; Naithani, Jaya; Remacle, Jean-François; Legat, Vincent; Deleersnijder, Eric
2017-04-01
Vertical discretisation is crucial in the modelling of lake thermocline oscillations. For finite element methods, a simple way to increase the resolution close to the oscillating thermocline is to use vertical adaptive coordinates. With an Arbitrary Lagrangian-Eulerian (ALE) formulation, the mesh can be adapted to increase the resolution in regions with strong shear or stratification. In such an application, consistency and conservativity must be strictly enforced. SLIM 3D, a discontinuous-Galerkin finite element model for shallow-water flows (www.climate.be/slim, e.g. Kärnä et al., 2013, Delandmeter et al., 2015), was designed to be strictly consistent and conservative in its discrete formulation. In this context, special care must be paid to the coupling of the external and internal modes of the model and the moving mesh algorithm. In this framework, the mesh can be adapted arbitrarily in the vertical direction. Two moving mesh algorithms were implemented: the first one computes an a-priori optimal mesh; the second one diffuses vertically the mesh (Burchard et al., 2004, Hofmeister et al., 2010). The criteria used to define the optimal mesh and the diffusion function are related to a suitable measure of shear and stratification. We will present in detail the design of the model and how the consistency and conservativity is obtained. Then we will apply it to both idealised benchmarks and the wind-forced thermocline oscillations in Lake Tanganyika (Naithani et al. 2002). References Tuomas Kärnä, Vincent Legat and Eric Deleersnijder. A baroclinic discontinuous Galerkin finite element model for coastal flows, Ocean Modelling, 61:1-20, 2013. Philippe Delandmeter, Stephen E Lewis, Jonathan Lambrechts, Eric Deleersnijder, Vincent Legat and Eric Wolanski. The transport and fate of riverine fine sediment exported to a semi-open system. Estuarine, Coastal and Shelf Science, 167:336-346, 2015. Hans Burchard and Jean-Marie Beckers. Non-uniform adaptive vertical grids in
Microstructure extraction and automatic quadrilateral mesh generation from rock images
NASA Astrophysics Data System (ADS)
Liu, Y.; Xing, H.
2011-12-01
With the development of SEM and/or MRI based techniques, digital images are nowadays widely used to describe the complicated material structures. It is possible to automatically establish complex models in the format of images but such kind of digital models are very difficult and even impossible to use in the conventional numerical analysis, and thus an automatic quadrilateral mesh generator is developed. It has following steps: (1) Reading data from a image with material property/microstructure information and extracting points with the specified material property; (2) smoothing the extracted digital image (i.e. noise removal) for a better image according to the user's prescribed parameters/requirements for resolution; (3) extracting and generating boundaries to identify microstructures according to pixel colors; (4) fixing ambiguous connections; (5) smoothing the above boundaries and then discretising them into edges; (6) taking the generated edges as input line constraints for automatic quadrilateral mesh generation; (7) Output the mesh for the further numerical (e.g. FEM, FDM, FVM) analysis.
NASA Astrophysics Data System (ADS)
Tonello, N.; Eude, Y.; de Laage de Meux, B.; Ferrand, M.
2017-01-01
The steady-state operation of the Francis-99, Tokke turbine [1-3] has been simulated numerically at different loads using the open source, CAD and CFD software, SALOME [4] Code_Saturne [5]. The full 3D mesh of the Tokke turbine provided for the Second Francis-99 Workshop has been adapted and modified to work with the solver. Results are compared for the frozen-rotor and the unsteady, conservative sliding mesh approach over three operating points, showing that good agreement with the experimental data is obtained with both models without having to tune the CFD models for each operating point. Approaches to the simulation of transient operation are also presented with results of work in progress.
Towards a theory of automated elliptic mesh generation
NASA Technical Reports Server (NTRS)
Cordova, J. Q.
1992-01-01
The theory of elliptic mesh generation is reviewed and the fundamental problem of constructing computational space is discussed. It is argued that the construction of computational space is an NP-Complete problem and therefore requires a nonstandard approach for its solution. This leads to the development of graph-theoretic, combinatorial optimization and integer programming algorithms. Methods for the construction of two dimensional computational space are presented.
Cartesian based grid generation/adaptive mesh refinement
NASA Technical Reports Server (NTRS)
Coirier, William J.
1992-01-01
Grid adaptation has recently received attention in the computational fluid dynamics (CFD) community as a means to capture the salient features of a flowfield by either moving grid points of a structured or by adding cells in an unstructured manner. An approach based on a background cartesian mesh is investigated from which the geometry is 'cut' out of the mesh. Once the mesh is obtained, a solution on this coarse grid is found, that indicates which cells need to be refined. This process of refining/solving continues until the flow is grid refined in terms of a user specified global parameter (such as drag coefficient etc.). The advantages of this approach are twofold: the generation of the base grid is independent of the topology of the bodies or surfaces around/through which the flow is to be computed, and the resulting grid (in uncut regions) is highly isotropic, so that the truncation error is low. The flow solver (which, along with the grid generation is still under development) uses a completely unstructured data base, and is a finite volume, upwinding scheme. Current and future work will address generating Navier-Stokes suitable grids by using locally aligned and normal face/cell refining. The attached plot shows a simple grid about two turbine blades.
NASA Astrophysics Data System (ADS)
Yang, Dan; Liu, Juan; Zhang, Yingxi; Li, Xin; Wang, Yongtian
2016-10-01
Holographic display has been considered as a promising display technology. Currently, low-speed generation of holograms with big holographic data is one of crucial bottlenecks for three dimensional (3D) dynamic holographic display. To solve this problem, the acceleration method computation platform is presented based on look-up table point source method. The computer generated holograms (CGHs) acquisition is sped up by offline file loading and inline calculation optimization, where a pure phase CGH with gigabyte data is encoded to record an object with 10 MB sampling data. Both numerical simulation and optical experiment demonstrate that the CGHs with 1920×1080 resolution by the proposed method can be applied to the 3D objects reconstruction with high quality successfully. It is believed that the CGHs with huge data can be generated by the proposed method with high speed for 3D dynamic holographic display in near future.
Generation of compartmentalized pressure by a nuclear piston governs cell motility in a 3D matrix.
Petrie, Ryan J; Koo, Hyun; Yamada, Kenneth M
2014-08-29
Cells use actomyosin contractility to move through three-dimensional (3D) extracellular matrices. Contractility affects the type of protrusions cells use to migrate in 3D, but the mechanisms are unclear. In this work, we found that contractility generated high-pressure lobopodial protrusions in human cells migrating in a 3D matrix. In these cells, the nucleus physically divided the cytoplasm into forward and rear compartments. Actomyosin contractility with the nucleoskeleton-intermediate filament linker protein nesprin-3 pulled the nucleus forward and pressurized the front of the cell. Reducing expression of nesprin-3 decreased and equalized the intracellular pressure. Thus, the nucleus can act as a piston that physically compartmentalizes the cytoplasm and increases the hydrostatic pressure between the nucleus and the leading edge of the cell to drive lamellipodia-independent 3D cell migration. Copyright © 2014, American Association for the Advancement of Science.
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.
A Novel Coarsening Method for Scalable and Efficient Mesh Generation
Yoo, A; Hysom, D; Gunney, B
2010-12-02
matrix-vector multiplication can be performed locally on each processor and hence to minimize communication. Furthermore, a good graph partitioning scheme ensures the equal amount of computation performed on each processor. Graph partitioning is a well known NP-complete problem, and thus the most commonly used graph partitioning algorithms employ some forms of heuristics. These algorithms vary in terms of their complexity, partition generation time, and the quality of partitions, and they tend to trade off these factors. A significant challenge we are currently facing at the Lawrence Livermore National Laboratory is how to partition very large meshes on massive-size distributed memory machines like IBM BlueGene/P, where scalability becomes a big issue. For example, we have found that the ParMetis, a very popular graph partitioning tool, can only scale to 16K processors. An ideal graph partitioning method on such an environment should be fast and scale to very large meshes, while producing high quality partitions. This is an extremely challenging task, as to scale to that level, the partitioning algorithm should be simple and be able to produce partitions that minimize inter-processor communications and balance the load imposed on the processors. Our goals in this work are two-fold: (1) To develop a new scalable graph partitioning method with good load balancing and communication reduction capability. (2) To study the performance of the proposed partitioning method on very large parallel machines using actual data sets and compare the performance to that of existing methods. The proposed method achieves the desired scalability by reducing the mesh size. For this, it coarsens an input mesh into a smaller size mesh by coalescing the vertices and edges of the original mesh into a set of mega-vertices and mega-edges. A new coarsening method called brick algorithm is developed in this research. In the brick algorithm, the zones in a given mesh are first grouped into fixed size
MeSH indexing based on automatically generated summaries
2013-01-01
Background MEDLINE citations are manually indexed at the U.S. National Library of Medicine (NLM) using as reference the Medical Subject Headings (MeSH) controlled vocabulary. For this task, the human indexers read the full text of the article. Due to the growth of MEDLINE, the NLM Indexing Initiative explores indexing methodologies that can support the task of the indexers. Medical Text Indexer (MTI) is a tool developed by the NLM Indexing Initiative to provide MeSH indexing recommendations to indexers. Currently, the input to MTI is MEDLINE citations, title and abstract only. Previous work has shown that using full text as input to MTI increases recall, but decreases precision sharply. We propose using summaries generated automatically from the full text for the input to MTI to use in the task of suggesting MeSH headings to indexers. Summaries distill the most salient information from the full text, which might increase the coverage of automatic indexing approaches based on MEDLINE. We hypothesize that if the results were good enough, manual indexers could possibly use automatic summaries instead of the full texts, along with the recommendations of MTI, to speed up the process while maintaining high quality of indexing results. Results We have generated summaries of different lengths using two different summarizers, and evaluated the MTI indexing on the summaries using different algorithms: MTI, individual MTI components, and machine learning. The results are compared to those of full text articles and MEDLINE citations. Our results show that automatically generated summaries achieve similar recall but higher precision compared to full text articles. Compared to MEDLINE citations, summaries achieve higher recall but lower precision. Conclusions Our results show that automatic summaries produce better indexing than full text articles. Summaries produce similar recall to full text but much better precision, which seems to indicate that automatic summaries can
MeSH indexing based on automatically generated summaries.
Jimeno-Yepes, Antonio J; Plaza, Laura; Mork, James G; Aronson, Alan R; Díaz, Alberto
2013-06-26
MEDLINE citations are manually indexed at the U.S. National Library of Medicine (NLM) using as reference the Medical Subject Headings (MeSH) controlled vocabulary. For this task, the human indexers read the full text of the article. Due to the growth of MEDLINE, the NLM Indexing Initiative explores indexing methodologies that can support the task of the indexers. Medical Text Indexer (MTI) is a tool developed by the NLM Indexing Initiative to provide MeSH indexing recommendations to indexers. Currently, the input to MTI is MEDLINE citations, title and abstract only. Previous work has shown that using full text as input to MTI increases recall, but decreases precision sharply. We propose using summaries generated automatically from the full text for the input to MTI to use in the task of suggesting MeSH headings to indexers. Summaries distill the most salient information from the full text, which might increase the coverage of automatic indexing approaches based on MEDLINE. We hypothesize that if the results were good enough, manual indexers could possibly use automatic summaries instead of the full texts, along with the recommendations of MTI, to speed up the process while maintaining high quality of indexing results. We have generated summaries of different lengths using two different summarizers, and evaluated the MTI indexing on the summaries using different algorithms: MTI, individual MTI components, and machine learning. The results are compared to those of full text articles and MEDLINE citations. Our results show that automatically generated summaries achieve similar recall but higher precision compared to full text articles. Compared to MEDLINE citations, summaries achieve higher recall but lower precision. Our results show that automatic summaries produce better indexing than full text articles. Summaries produce similar recall to full text but much better precision, which seems to indicate that automatic summaries can efficiently capture the most
Kilo-scale droplet generation in three-dimensional monolithic elastomer device (3D MED).
Jeong, Heon-Ho; Yelleswarapu, Venkata R; Yadavali, Sagar; Issadore, David; Lee, Daeyeon
2015-12-07
Droplet-based microfluidics has led to transformational new approaches in diverse areas including materials synthesis and high-throughput biological assays. However, the translation of droplet microfluidics technology into commercial applications requires scale-up of droplet generation from the laboratory (<10 mL h(-1)) to the industrial (>1 L h(-1)) scale. To address this challenge, we develop a three-dimensional monolithic elastomer device (3D MED) for mass production of monodisperse emulsion droplets. Using double-sided imprinting, 3D microchannels are formed in a single elastomer piece that has 1000 parallel flow focusing generators (k-FFGs). Compared to previous work that parallelizes droplet generation, the 3D MED eliminates the needs for alignment and bonding of multiple pieces and thus makes it possible to achieve the high flow rates and pressure necessary for the kilo-scale generation of droplets. Using this approach, we demonstrate mass production of water-in-oil (W/O) emulsion droplets at production rates as high as 1.5 L h(-1) (>30 billion 45 μm diameter droplets per hour), with a coefficient of variation of droplet diameter of only 6.6%. Because of the simplicity, robustness, and manufacturability of our 3D MED architecture, it is well suited to bridge the gap between the continuously growing library of promising microfluidic technologies to generate microparticles that have been demonstrated in laboratory settings and their successful application in industry.
Software for browsing sectioned images of a dog body and generating a 3D model.
Park, Jin Seo; Jung, Yong Wook
2016-01-01
The goals of this study were (1) to provide accessible and instructive browsing software for sectioned images and a portable document format (PDF) file that includes three-dimensional (3D) models of an entire dog body and (2) to develop techniques for segmentation and 3D modeling that would enable an investigator to perform these tasks without the aid of a computer engineer. To achieve these goals, relatively important or large structures in the sectioned images were outlined to generate segmented images. The sectioned and segmented images were then packaged into browsing software. In this software, structures in the sectioned images are shown in detail and in real color. After 3D models were made from the segmented images, the 3D models were exported into a PDF file. In this format, the 3D models could be manipulated freely. The browsing software and PDF file are available for study by students, for lecture for teachers, and for training for clinicians. These files will be helpful for anatomical study by and clinical training of veterinary students and clinicians. Furthermore, these techniques will be useful for researchers who study two-dimensional images and 3D models.
Accuracy Based Generation of Thermodynamic Properties for Light Water in RELAP5-3D
Cliff B. Davis
2010-09-01
RELAP5-3D interpolates to obtain thermodynamic properties for use in its internal calculations. The accuracy of the interpolation was determined for the original steam tables currently used by the code. This accuracy evaluation showed that the original steam tables are generally detailed enough to allow reasonably accurate interpolations in most areas needed for typical analyses of nuclear reactors cooled by light water. However, there were some regions in which the original steam tables were judged to not provide acceptable accurate results. Revised steam tables were created that used a finer thermodynamic mesh between 4 and 21 MPa and 530 and 640 K. The revised steam tables solved most of the problems observed with the original steam tables. The accuracies of the original and revised steam tables were compared throughout the thermodynamic grid.
Coupling of a 3-D vortex particle-mesh method with a finite volume near-wall solver
NASA Astrophysics Data System (ADS)
Marichal, Y.; Lonfils, T.; Duponcheel, M.; Chatelain, P.; Winckelmans, G.
2011-11-01
This coupling aims at improving the computational efficiency of high Reynolds number bluff body flow simulations by using two complementary methods and exploiting their respective advantages in distinct parts of the domain. Vortex particle methods are particularly well suited for free vortical flows such as wakes or jets (the computational domain -with non zero vorticity- is then compact and dispersion errors are negligible). Finite volume methods, however, can handle boundary layers much more easily due to anisotropic mesh refinement. In the present approach, the vortex method is used in the whole domain (overlapping domain technique) but its solution is highly underresolved in the vicinity of the wall. It thus has to be corrected by the near-wall finite volume solution at each time step. Conversely, the vortex method provides the outer boundary conditions for the near-wall solver. A parallel multi-resolution vortex particle-mesh approach is used here along with an Immersed Boundary method in order to take the walls into account. The near-wall flow is solved by OpenFOAM® using the PISO algorithm. We validate the methodology on the flow past a sphere at a moderate Reynolds number. F.R.S. - FNRS Research Fellow.
NASA Astrophysics Data System (ADS)
Destrez, Raphaël.; Albouy-Kissi, Benjamin; Treuillet, Sylvie; Lucas, Yves
2015-04-01
Computer aided planning for orthodontic treatment requires knowing occlusion of separately scanned dental casts. A visual guided registration is conducted starting by extracting corresponding features in both photographs and 3D scans. To achieve this, dental neck and occlusion surface are firstly extracted by image segmentation and 3D curvature analysis. Then, an iterative registration process is conducted during which feature positions are refined, guided by previously found anatomic edges. The occlusal edge image detection is improved by an original algorithm which follows Canny's poorly detected edges using a priori knowledge of tooth shapes. Finally, the influence of feature extraction and position optimization is evaluated in terms of the quality of the induced registration. Best combination of feature detection and optimization leads to a positioning average error of 1.10 mm and 2.03°.
3D conductive coupling for efficient generation of prominent Fano resonances in metamaterials
NASA Astrophysics Data System (ADS)
Liu, Zhiguang; Liu, Zhe; Li, Jiafang; Li, Wuxia; Li, Junjie; Gu, Changzhi; Li, Zhi-Yuan
2016-06-01
We demonstrate a 3D conductive coupling mechanism for the efficient generation of prominent and robust Fano resonances in 3D metamaterials (MMs) formed by integrating vertical U-shape split-ring resonators (SRRs) or vertical rectangular plates along a planar metallic hole array with extraordinary optical transmission (EOT). In such a configuration, intensified vertical E-field is induced along the metallic holes and naturally excites the electric resonances of the vertical structures, which form non-radiative “dark” modes. These 3D conductive “dark” modes strongly interfere with the “bright” resonance mode of the EOT structure, generating significant Fano resonances with both prominent destructive and constructive interferences. The demonstrated 3D conductive coupling mechanism is highly universal in that both 3D MMs with vertical SRRs and vertical plates exhibit the same prominent Fano resonances despite their dramatic structural difference, which is conceptually different from conventional capacitive and inductive coupling mechanisms that degraded drastically upon small structural deviations.
3D dendritic gold nanostructures: seeded growth of a multi-generation fractal architecture.
Pan, Ming; Xing, Shuangxi; Sun, Ting; Zhou, Wenwen; Sindoro, Melinda; Teo, Hui Hian; Yan, Qingyu; Chen, Hongyu
2010-10-14
In this report, we focus on the synthetic challenges for nanoscale 3D fractal architectures, namely the multi-generation growth with control in both size uniformity and colloidal stability; by directing the simultaneous growth of Au and polyaniline on Au seeds, fractal nanoparticles can be achieved with a topology distinctively different from those of spheres, cubes or rods.
Fonseca, T C Ferreira; Bogaerts, R; Lebacq, A L; Mihailescu, C L; Vanhavere, F
2014-04-01
A realistic computational 3D human body library, called MaMP and FeMP (Male and Female Mesh Phantoms), based on polygonal mesh surface geometry, has been created to be used for numerical calibration of the whole body counter (WBC) system of the nuclear power plant (NPP) in Doel, Belgium. The main objective was to create flexible computational models varying in gender, body height, and mass for studying the morphology-induced variation of the detector counting efficiency (CE) and reducing the measurement uncertainties. First, the counting room and an HPGe detector were modeled using MCNPX (Monte Carlo radiation transport code). The validation of the model was carried out for different sample-detector geometries with point sources and a physical phantom. Second, CE values were calculated for a total of 36 different mesh phantoms in a seated position using the validated Monte Carlo model. This paper reports on the validation process of the in vivo whole body system and the CE calculated for different body heights and weights. The results reveal that the CE is strongly dependent on the individual body shape, size, and gender and may vary by a factor of 1.5 to 3 depending on the morphology aspects of the individual to be measured.
Automatic generation of 3D motifs for classification of protein binding sites
Nebel, Jean-Christophe; Herzyk, Pawel; Gilbert, David R
2007-01-01
Background Since many of the new protein structures delivered by high-throughput processes do not have any known function, there is a need for structure-based prediction of protein function. Protein 3D structures can be clustered according to their fold or secondary structures to produce classes of some functional significance. A recent alternative has been to detect specific 3D motifs which are often associated to active sites. Unfortunately, there are very few known 3D motifs, which are usually the result of a manual process, compared to the number of sequential motifs already known. In this paper, we report a method to automatically generate 3D motifs of protein structure binding sites based on consensus atom positions and evaluate it on a set of adenine based ligands. Results Our new approach was validated by generating automatically 3D patterns for the main adenine based ligands, i.e. AMP, ADP and ATP. Out of the 18 detected patterns, only one, the ADP4 pattern, is not associated with well defined structural patterns. Moreover, most of the patterns could be classified as binding site 3D motifs. Literature research revealed that the ADP4 pattern actually corresponds to structural features which show complex evolutionary links between ligases and transferases. Therefore, all of the generated patterns prove to be meaningful. Each pattern was used to query all PDB proteins which bind either purine based or guanine based ligands, in order to evaluate the classification and annotation properties of the pattern. Overall, our 3D patterns matched 31% of proteins with adenine based ligands and 95.5% of them were classified correctly. Conclusion A new metric has been introduced allowing the classification of proteins according to the similarity of atomic environment of binding sites, and a methodology has been developed to automatically produce 3D patterns from that classification. A study of proteins binding adenine based ligands showed that these 3D patterns are not
MESH2D GRID GENERATOR DESIGN AND USE
Flach, G.; Smith, F.
2012-01-20
Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j{sub 0}) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations. The overall mesh is constructed from grid zones that are typically then subdivided into a collection of smaller grid cells. The grid zones usually correspond to distinct materials or larger-scale geometric shapes. The structured grid zones are identified through uppercase indices (I,J). Subdivision of zonal regions into grid cells can be done uniformly, or nonuniformly using either a polynomial or geometric skewing algorithm. Grid cells may be concentrated backward, forward, or toward both ends. Figure 1 illustrates the above concepts in the context of a simple four zone grid.
Unified framework for generation of 3D web visualization for mechatronic systems
NASA Astrophysics Data System (ADS)
Severa, O.; Goubej, M.; Konigsmarkova, J.
2015-11-01
The paper deals with development of a unified framework for generation of 3D visualizations of complex mechatronic systems. It provides a high-fidelity representation of executed motion by allowing direct employment of a machine geometry model acquired from a CAD system. Open-architecture multi-platform solution based on latest web standards is achieved by utilizing a web browser as a final 3D renderer. The results are applicable both for simulations and development of real-time human machine interfaces. Case study of autonomous underwater vehicle control is provided to demonstrate the applicability of the proposed approach.
3D calculation of boiling in complex geometry of steam generator
Ravnikar, I.; Petelin, S.
1996-11-01
The D4 steam generator of nuclear power plant Krsko was analyzed from a thermal-hydraulic point of view using the 3D PHOENICS computer code. The calculations were carried out for different operating conditions based on plugging study that was performed using 1D steam generator model SMUP computer code. Void fraction, velocity and enthalpy distributions were then obtained in the U-tube riser section.
Sentís, Manuel Lorenzo; Gable, Carl Walter
2017-06-01
There are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools will providemore » more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 (Pruess et al., 1999) to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. Here in this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.« less
A novel design for a wearable thermoelectric generator based on 3D fabric structure
NASA Astrophysics Data System (ADS)
Wu, Qian; Hu, Jinlian
2017-04-01
A flexible and wearable thermoelectric generator (TEG) could enable the conversion of human body heat into electrical power, which would help to realize a self-powered wearable electronic system. To overcome the difficulty of wearing existing flexible film TEGs, a novel 3D fabric TEG structure is designed in this study. By using a 3D fabric as the substrate and yarns coated with thermoelectric materials as legs, a wearable and flexible TEG can be realized. The designed generator has a sandwich structure, similar to the classical inorganic generator, which allows the generation of a temperature difference in the fabric thickness direction, thus making it wearable and showing promising application in body heat conversion. To verify the effectiveness of the designed generator structure, a prototype was fabricated, using a locknit spacer fabric as the substrate and yarns coated with waterborne polyurethane/carbon nanotube thermoelectric composites as legs. The results suggest that the fabricated spacer fabric TEG prototype could work successfully, although the performance of this prototype is of a low level. To further improve the efficiency of the 3D fabric generator and apply it in wearable electronics in the future, highly efficient inorganic thermoelectric materials can be applied, and modifications on the conductive connections can be made.
Microchip-based 3D-Cell Culture Using Polymer Nanofibers Generated by Solution Blow Spinning.
Chen, Chengpeng; Townsend, Alexandra D; Sell, Scott A; Martin, R Scott
2017-06-14
Polymer nano/micro fibers have found many applications including 3D cell culture and the creation of wound dressings. The fibers can be produced by a variety of techniques that include electrospinning, the primary disadvantage of which include the requirement for a high voltage supply (which may cause issues such as polymer denaturation) and lack of portability. More recently, solution blow spinning, where a high velocity sheath gas is used instead of high voltage, has been used to generate polymer fibers. In this work, we used blow spinning to create nano/microfibers for microchip-based 3D cell culture. First, we thoroughly investigated fiber generation from a 3D printed gas sheath device using two polymers that are amenable to cell culture (polycaprolactone, PCL and polystyrene, PS) as well as the parameters that can affect PCL and PS fiber quality. Using the 3D printed sheath device, it was found that the pressure of the sheath N2 and the concentration of polymer solutions determine if fibers can be produced as well as the resulting fiber morphology. In addition, we showed how these fibers can be used for 3D cell culture by directly depositing PCL fibers in petri dishes and well plates. It is shown the fibers have good compatibility with RAW 264.7 macrophages and the PCL fiber scaffold can be as thick as 178 ± 14 μm. PCL fibers created from solution blow spinning (with the 3D printed sheath device) were then integrated with a microfluidic device for the first time to fabricate a 3D cell culture scaffold with a flow component. After culturing and stimulating macrophages on the fluidic device, it was found that the integrated 3D fibrous scaffold is a better mimic of the extracellular matrix (as opposed to a flat, 2D substrate), with enhanced nitrite accumulation (product of nitric oxide release) from macrophages stimulated with lipopolysaccharide. PS fibers were also made and integrated in a microfluidic device for 3D culture of endothelial cells, which stayed
Radon transform based automatic metal artefacts generation for 3D threat image projection
NASA Astrophysics Data System (ADS)
Megherbi, Najla; Breckon, Toby P.; Flitton, Greg T.; Mouton, Andre
2013-10-01
Threat Image Projection (TIP) plays an important role in aviation security. In order to evaluate human security screeners in determining threats, TIP systems project images of realistic threat items into the images of the passenger baggage being scanned. In this proof of concept paper, we propose a 3D TIP method which can be integrated within new 3D Computed Tomography (CT) screening systems. In order to make the threat items appear as if they were genuinely located in the scanned bag, appropriate CT metal artefacts are generated in the resulting TIP images according to the scan orientation, the passenger bag content and the material of the inserted threat items. This process is performed in the projection domain using a novel methodology based on the Radon Transform. The obtained results using challenging 3D CT baggage images are very promising in terms of plausibility and realism.
Unconstrained paving and plastering method for generating finite element meshes
Staten, Matthew L.; Owen, Steven J.; Blacker, Teddy D.; Kerr, Robert
2010-03-02
Computer software for and a method of generating a conformal all quadrilateral or hexahedral mesh comprising selecting an object with unmeshed boundaries and performing the following while unmeshed voids are larger than twice a desired element size and unrecognizable as either a midpoint subdividable or pave-and-sweepable polyhedra: selecting a front to advance; based on sizes of fronts and angles with adjacent fronts, determining which adjacent fronts should be advanced with the selected front; advancing the fronts; detecting proximities with other nearby fronts; resolving any found proximities; forming quadrilaterals or unconstrained columns of hexahedra where two layers cross; and establishing hexahedral elements where three layers cross.
3D texture analysis for classification of second harmonic generation images of human ovarian cancer
NASA Astrophysics Data System (ADS)
Wen, Bruce; Campbell, Kirby R.; Tilbury, Karissa; Nadiarnykh, Oleg; Brewer, Molly A.; Patankar, Manish; Singh, Vikas; Eliceiri, Kevin. W.; Campagnola, Paul J.
2016-10-01
Remodeling of the collagen architecture in the extracellular matrix (ECM) has been implicated in ovarian cancer. To quantify these alterations we implemented a form of 3D texture analysis to delineate the fibrillar morphology observed in 3D Second Harmonic Generation (SHG) microscopy image data of normal (1) and high risk (2) ovarian stroma, benign ovarian tumors (3), low grade (4) and high grade (5) serous tumors, and endometrioid tumors (6). We developed a tailored set of 3D filters which extract textural features in the 3D image sets to build (or learn) statistical models of each tissue class. By applying k-nearest neighbor classification using these learned models, we achieved 83–91% accuracies for the six classes. The 3D method outperformed the analogous 2D classification on the same tissues, where we suggest this is due the increased information content. This classification based on ECM structural changes will complement conventional classification based on genetic profiles and can serve as an additional biomarker. Moreover, the texture analysis algorithm is quite general, as it does not rely on single morphological metrics such as fiber alignment, length, and width but their combined convolution with a customizable basis set.
3D texture analysis for classification of second harmonic generation images of human ovarian cancer
Wen, Bruce; Campbell, Kirby R.; Tilbury, Karissa; Nadiarnykh, Oleg; Brewer, Molly A.; Patankar, Manish; Singh, Vikas; Eliceiri, Kevin. W.; Campagnola, Paul J.
2016-01-01
Remodeling of the collagen architecture in the extracellular matrix (ECM) has been implicated in ovarian cancer. To quantify these alterations we implemented a form of 3D texture analysis to delineate the fibrillar morphology observed in 3D Second Harmonic Generation (SHG) microscopy image data of normal (1) and high risk (2) ovarian stroma, benign ovarian tumors (3), low grade (4) and high grade (5) serous tumors, and endometrioid tumors (6). We developed a tailored set of 3D filters which extract textural features in the 3D image sets to build (or learn) statistical models of each tissue class. By applying k-nearest neighbor classification using these learned models, we achieved 83–91% accuracies for the six classes. The 3D method outperformed the analogous 2D classification on the same tissues, where we suggest this is due the increased information content. This classification based on ECM structural changes will complement conventional classification based on genetic profiles and can serve as an additional biomarker. Moreover, the texture analysis algorithm is quite general, as it does not rely on single morphological metrics such as fiber alignment, length, and width but their combined convolution with a customizable basis set. PMID:27767180
Falomir, Zoe; Kluth, Thomas
2017-06-24
The challenge of describing 3D real scenes is tackled in this paper using qualitative spatial descriptors. A key point to study is which qualitative descriptors to use and how these qualitative descriptors must be organized to produce a suitable cognitive explanation. In order to find answers, a survey test was carried out with human participants which openly described a scene containing some pieces of furniture. The data obtained in this survey are analysed, and taking this into account, the QSn3D computational approach was developed which uses a XBox 360 Kinect to obtain 3D data from a real indoor scene. Object features are computed on these 3D data to identify objects in indoor scenes. The object orientation is computed, and qualitative spatial relations between the objects are extracted. These qualitative spatial relations are the input to a grammar which applies saliency rules obtained from the survey study and generates cognitive natural language descriptions of scenes. Moreover, these qualitative descriptors can be expressed as first-order logical facts in Prolog for further reasoning. Finally, a validation study is carried out to test whether the descriptions provided by QSn3D approach are human readable. The obtained results show that their acceptability is higher than 82%.
The Evaluation of Steam Generator Level Measurement Model for OPR1000 Using RETRAN-3D
Doo Yong Lee; Soon Joon Hong; Byung Chul Lee; Heok Soon Lim
2006-07-01
Steam generator level measurement is important factor for plant transient analyses using best estimate thermal hydraulic computer codes since the value of steam generator level is used for steam generator level control system and plant protection system. Because steam generator is in the saturation condition which includes steam and liquid together and is the place that heat exchange occurs from primary side to secondary side, computer codes are hard to calculate steam generator level realistically without appropriate level measurement model. In this paper, we prepare the steam generator models using RETRAN-3D that include geometry models, full range feedwater control system and five types of steam generator level measurement model. Five types of steam generator level measurement model consist of level measurement model using elevation difference in downcomer, 1D level measurement model using fluid mass, 1D level measurement model using fluid volume, 2D level measurement model using power and fluid mass, and 2D level measurement model using power and fluid volume. And we perform the evaluation of the capability of each steam generator level measurement model by simulating the real plant transient condition, the title is 'Reactor Trip by The Failure of The Deaerator Level Control Card of Ulchin Unit 3'. The comparison results between real plant data and RETRAN-3D analyses for each steam generator level measurement model show that 2D level measurement model using power and fluid mass or fluid volume has more realistic prediction capability compared with other level measurement models. (authors)
Generation of arbitrary order Bessel beams via 3D printed axicons at the terahertz frequency range.
Wei, Xuli; Liu, Changming; Niu, Liting; Zhang, Zhongqi; Wang, Kejia; Yang, Zhengang; Liu, Jinsong
2015-12-20
We present the generation of arbitrary order Bessel beams at 0.3 THz through the implementation of suitably designed axicons based on 3D printing technology. The helical axicons, which possess thickness gradients in both radial and azimuthal directions, can convert the incident Gaussian beam into a high-order Bessel beam with spiral phase structure. The evolution of the generated Bessel beams are characterized experimentally with a three-dimensional field scanner. Moreover, the topological charges carried by the high-order Bessel beams are determined by the fork-like interferograms. This 3D-printing-based Bessel beam generation technique is useful not only for THz imaging systems with zero-order Bessel beams but also for future orbital-angular-momentum-based THz free-space communication with higher-order Bessel beams.
Sabhachandani, P; Motwani, V; Cohen, N; Sarkar, S; Torchilin, V; Konry, T
2016-02-07
Here we describe a robust, microfluidic technique to generate and analyze 3D tumor spheroids, which resembles tumor microenvironment and can be used as a more effective preclinical drug testing and screening model. Monodisperse cell-laden alginate droplets were generated in polydimethylsiloxane (PDMS) microfluidic devices that combine T-junction droplet generation and external gelation for spheroid formation. The proposed approach has the capability to incorporate multiple cell types. For the purposes of our study, we generated spheroids with breast cancer cell lines (MCF-7 drug sensitive and resistant) and co-culture spheroids of MCF-7 together with a fibroblast cell line (HS-5). The device has the capability to house 1000 spheroids on chip for drug screening and other functional analysis. Cellular viability of spheroids in the array part of the device was maintained for two weeks by continuous perfusion of complete media into the device. The functional performance of our 3D tumor models and a dose dependent response of standard chemotherapeutic drug, doxorubicin (Dox) and standard drug combination Dox and paclitaxel (PCT) was analyzed on our chip-based platform. Altogether, our work provides a simple and novel, in vitro platform to generate, image and analyze uniform, 3D monodisperse alginate hydrogel tumors for various omic studies and therapeutic efficiency screening, an important translational step before in vivo studies.
Nava, José L; Sirés, Ignasi; Brillas, Enric
2014-01-01
This paper compares the performance of 2D (plate) and 3D (mesh) boron-doped diamond (BDD) electrodes, fitted into a filter-press reactor, during the electrochemical incineration of indigo textile dye as a model organic compound in chloride medium. The electrolyses were carried out in the FM01-LC reactor at mean fluid velocities between 0.9 ≤ u ≤ 10.4 and 1.2 ≤ u ≤ 13.9 cm s(-1) for the 2D BDD and the 3D BDD electrodes, respectively, at current densities of 5.63 and 15 mA cm(-2). The oxidation of the organic matter was promoted, on the one hand, via the physisorbed hydroxyl radicals (BDD(·OH)) formed from water oxidation at the BDD surface and, on the other hand, via active chlorine formed from the oxidation of chloride ions on BDD. The performance of 2D BDD and 3D BDD electrodes in terms of current efficiency, energy consumption, and charge passage during the treatments is discussed.
A Depth Map Generation Algorithm Based on Saliency Detection for 2D to 3D Conversion
NASA Astrophysics Data System (ADS)
Yang, Yizhong; Hu, Xionglou; Wu, Nengju; Wang, Pengfei; Xu, Dong; Rong, Shen
2017-09-01
In recent years, 3D movies attract people's attention more and more because of their immersive stereoscopic experience. However, 3D movies is still insufficient, so estimating depth information for 2D to 3D conversion from a video is more and more important. In this paper, we present a novel algorithm to estimate depth information from a video via scene classification algorithm. In order to obtain perceptually reliable depth information for viewers, the algorithm classifies them into three categories: landscape type, close-up type, linear perspective type firstly. Then we employ a specific algorithm to divide the landscape type image into many blocks, and assign depth value by similar relative height cue with the image. As to the close-up type image, a saliency-based method is adopted to enhance the foreground in the image and the method combine it with the global depth gradient to generate final depth map. By vanishing line detection, the calculated vanishing point which is regarded as the farthest point to the viewer is assigned with deepest depth value. According to the distance between the other points and the vanishing point, the entire image is assigned with corresponding depth value. Finally, depth image-based rendering is employed to generate stereoscopic virtual views after bilateral filter. Experiments show that the proposed algorithm can achieve realistic 3D effects and yield satisfactory results, while the perception scores of anaglyph images lie between 6.8 and 7.8.
Mixing in 3D Sparse Multi-Scale Grid Generated Turbulence
NASA Astrophysics Data System (ADS)
Usama, Syed; Kopec, Jacek; Tellez, Jackson; Kwiatkowski, Kamil; Redondo, Jose; Malik, Nadeem
2017-04-01
Flat 2D fractal grids are known to alter turbulence characteristics downstream of the grid as compared to the regular grids with the same blockage ratio and the same mass inflow rates [1]. This has excited interest in the turbulence community for possible exploitation for enhanced mixing and related applications. Recently, a new 3D multi-scale grid design has been proposed [2] such that each generation of length scale of turbulence grid elements is held in its own frame, the overall effect is a 3D co-planar arrangement of grid elements. This produces a 'sparse' grid system whereby each generation of grid elements produces a turbulent wake pattern that interacts with the other wake patterns downstream. A critical motivation here is that the effective blockage ratio in the 3D Sparse Grid Turbulence (3DSGT) design is significantly lower than in the flat 2D counterpart - typically the blockage ratio could be reduced from say 20% in 2D down to 4% in the 3DSGT. If this idea can be realized in practice, it could potentially greatly enhance the efficiency of turbulent mixing and transfer processes clearly having many possible applications. Work has begun on the 3DSGT experimentally using Surface Flow Image Velocimetry (SFIV) [3] at the European facility in the Max Planck Institute for Dynamics and Self-Organization located in Gottingen, Germany and also at the Technical University of Catalonia (UPC) in Spain, and numerically using Direct Numerical Simulation (DNS) at King Fahd University of Petroleum & Minerals (KFUPM) in Saudi Arabia and in University of Warsaw in Poland. DNS is the most useful method to compare the experimental results with, and we are studying different types of codes such as Imcompact3d, and OpenFoam. Many variables will eventually be investigated for optimal mixing conditions. For example, the number of scale generations, the spacing between frames, the size ratio of grid elements, inflow conditions, etc. We will report upon the first set of findings
Dense 3d Point Cloud Generation from Uav Images from Image Matching and Global Optimazation
NASA Astrophysics Data System (ADS)
Rhee, S.; Kim, T.
2016-06-01
3D spatial information from unmanned aerial vehicles (UAV) images is usually provided in the form of 3D point clouds. For various UAV applications, it is important to generate dense 3D point clouds automatically from over the entire extent of UAV images. In this paper, we aim to apply image matching for generation of local point clouds over a pair or group of images and global optimization to combine local point clouds over the whole region of interest. We tried to apply two types of image matching, an object space-based matching technique and an image space-based matching technique, and to compare the performance of the two techniques. The object space-based matching used here sets a list of candidate height values for a fixed horizontal position in the object space. For each height, its corresponding image point is calculated and similarity is measured by grey-level correlation. The image space-based matching used here is a modified relaxation matching. We devised a global optimization scheme for finding optimal pairs (or groups) to apply image matching, defining local match region in image- or object- space, and merging local point clouds into a global one. For optimal pair selection, tiepoints among images were extracted and stereo coverage network was defined by forming a maximum spanning tree using the tiepoints. From experiments, we confirmed that through image matching and global optimization, 3D point clouds were generated successfully. However, results also revealed some limitations. In case of image-based matching results, we observed some blanks in 3D point clouds. In case of object space-based matching results, we observed more blunders than image-based matching ones and noisy local height variations. We suspect these might be due to inaccurate orientation parameters. The work in this paper is still ongoing. We will further test our approach with more precise orientation parameters.
Unstructured Grid Generation for Complex 3D High-Lift Configurations
NASA Technical Reports Server (NTRS)
Pirzadeh, Shahyar Z.
1999-01-01
The application of an unstructured grid methodology on a three-dimensional high-lift configuration is presented. The focus of this paper is on the grid generation aspect of an integrated effort for the development of an unstructured-grid computational fluid dynamics (CFD) capability at the NASA Langley Research Center. The meshing approach is based on tetrahedral grids generated by the advancing-front and the advancing-layers procedures. The capability of the method for solving high-lift problems is demonstrated on an aircraft model referred to as the energy efficient transport configuration. The grid generation issues, including the pros and cons of the present approach, are discussed in relation to the high-lift problems. Limited viscous flow results are presented to demonstrate the viability of the generated grids. A corresponding Navier-Stokes solution capability, along with further computations on the present grid, is presented in a companion SAE paper.
2012-01-04
GEN3D is a three-dimensional mesh generation program. The three-dimensional mesh is generated by mapping a two-dimensional mesh into threedimensions according to one of four types of transformations: translating, rotating, mapping onto a spherical surface, and mapping onto a cylindrical surface. The generated three-dimensional mesh can then be reoriented by offsetting, reflecting about an axis, and revolving about an axis. GEN3D can be used to mesh geometries that are axisymmetric or planar, but, due to three-dimensional loading or boundary conditions, require a three-dimensional finite element mesh and analysis. More importantly, it can be used to mesh complex three-dimensional geometries composed of several sections when the sections can be defined in terms of transformations of two dimensional geometries. The code GJOIN is then used to join the separate sections into a single body. GEN3D reads and writes twodimensional and threedimensional mesh databases in the GENESIS database format; therefore, it is compatible with the preprocessing, postprocessing, and analysis codes used by the Engineering Analysis Department at Sandia National Laboratories, Albuquerque, NM.
3D SPH numerical simulation of the wave generated by the Vajont rockslide
NASA Astrophysics Data System (ADS)
Vacondio, R.; Mignosa, P.; Pagani, S.
2013-09-01
A 3D numerical modeling of the wave generated by the Vajont slide, one of the most destructive ever occurred, is presented in this paper. A meshless Lagrangian Smoothed Particle Hydrodynamics (SPH) technique was adopted to simulate the highly fragmented violent flow generated by the falling slide in the artificial reservoir. The speed-up achievable via General Purpose Graphic Processing Units (GP-GPU) allowed to adopt the adequate resolution to describe the phenomenon. The comparison with the data available in literature showed that the results of the numerical simulation reproduce satisfactorily the maximum run-up, also the water surface elevation in the residual lake after the event. Moreover, the 3D velocity field of the flow during the event and the discharge hydrograph which overtopped the dam, were obtained.
Design and verification of diffractive optical elements for speckle generation of 3-D range sensors
NASA Astrophysics Data System (ADS)
Du, Pei-Qin; Shih, Hsi-Fu; Chen, Jenq-Shyong; Wang, Yi-Shiang
2016-12-01
The optical projection using speckles is one of the structured light methods that have been applied to three-dimensional (3-D) range sensors. This paper investigates the design and fabrication of diffractive optical elements (DOEs) for generating the light field with uniformly distributed speckles. Based on the principles of computer generated holograms, the iterative Fourier transform algorithm was adopted for the DOE design. It was used to calculate the phase map for diffracting the incident laser beam into a goal pattern with distributed speckles. Four patterns were designed in the study. Their phase maps were first examined by a spatial light modulator and then fabricated on glass substrates by microfabrication processes. Finally, the diffraction characteristics of the fabricated devices were verified. The experimental results show that the proposed methods are applicable to the DOE design of 3-D range sensors. Furthermore, any expected diffraction area and speckle density could be possibly achieved according to the relations presented in the paper.
Hortolà, Policarp
2010-01-01
When dealing with microscopic still images of some kinds of samples, the out-of-focus problem represents a particularly serious limiting factor for the subsequent generation of fully sharp 3D animations. In order to produce fully-focused 3D animations of strongly uneven surface microareas, a vertical stack of six digital secondary-electron SEM micrographs of a human bloodstain microarea was acquired. Afterwards, single combined images were generated using a macrophotography and light microscope image post-processing software. Subsequently, 3D animations of texture and topography were obtained in different formats using a combination of software tools. Finally, a 3D-like animation of a texture-topography composite was obtained in different formats using another combination of software tools. By one hand, results indicate that the use of image post-processing software not concerned primarily with electron micrographs allows to obtain, in an easy way, fully-focused images of strongly uneven surface microareas of bloodstains from small series of partially out-of-focus digital SEM micrographs. On the other hand, results also indicate that such small series of electron micrographs can be utilized for generating 3D and 3D-like animations that can subsequently be converted into different formats, by using certain user-friendly software facilities not originally designed for use in SEM, that are easily available from Internet. Although the focus of this study was on bloodstains, the methods used in it well probably are also of relevance for studying the surface microstructures of other organic or inorganic materials whose sharp displaying is difficult of obtaining from a single SEM micrograph.
Generation of 3-D surface maps in waste storage silos using a structured light source
NASA Technical Reports Server (NTRS)
Burks, B. L.; Rowe, J. C.; Dinkins, M. A.; Christensen, B.; Selleck, C.; Jacoboski, D.; Markus, R.
1992-01-01
Surface contours inside the large waste storage tanks typical of the Department of Energy (DOE) complex are, in general, highly irregular. In addition to pipes and other pieces of equipment in the tanks, the surfaces may have features such as mounds, fissures, crystalline structures, and mixed solid and liquid forms. Prior to remediation activities, it will be necessary to characterize the waste to determine the most effective remediation approaches. Surface contour data will be required both prior to and during remediation. The use is described of a structured light source to generate 3-D surface contour maps of the interior of waste storage silos at the Feed Materials Production Center at Fernald, OH. The landscape inside these large waste storage tanks bears a strong resemblance to some of the landscapes that might be encountered during lunar or planetary exploration. Hence, these terrestrial 3-D mapping techniques may be directly applicable to extraterrestrial exploration. In further development, it will be demonstrated that these 3-D data can be used for robotic task planning just as 3-D surface contour data of a satellite could be used to plan maintenance tasks for a space-based servicing robot.
Generation of 3-D surface maps in waste storage silos using a structured light source
NASA Technical Reports Server (NTRS)
Burks, B. L.; Rowe, J. C.; Dinkins, M. A.; Christensen, B.; Selleck, C.; Jacoboski, D.; Markus, R.
1992-01-01
Surface contours inside the large waste storage tanks typical of the Department of Energy (DOE) complex are, in general, highly irregular. In addition to pipes and other pieces of equipment in the tanks, the surfaces may have features such as mounds, fissures, crystalline structures, and mixed solid and liquid forms. Prior to remediation activities, it will be necessary to characterize the waste to determine the most effective remediation approaches. Surface contour data will be required both prior to and during remediation. The use is described of a structured light source to generate 3-D surface contour maps of the interior of waste storage silos at the Feed Materials Production Center at Fernald, OH. The landscape inside these large waste storage tanks bears a strong resemblance to some of the landscapes that might be encountered during lunar or planetary exploration. Hence, these terrestrial 3-D mapping techniques may be directly applicable to extraterrestrial exploration. In further development, it will be demonstrated that these 3-D data can be used for robotic task planning just as 3-D surface contour data of a satellite could be used to plan maintenance tasks for a space-based servicing robot.
NASA Astrophysics Data System (ADS)
Patil, Umakant; Lee, Su Chan; Kulkarni, Sachin; Sohn, Ji Soo; Nam, Min Sik; Han, Suhyun; Jun, Seong Chan
2015-04-01
Nowadays, advancement in performance of proficient multifarious electrode materials lies conclusively at the core of research concerning energy storage devices. To accomplish superior capacitance performance the requirements of high capacity, better cyclic stability and good rate capability can be expected from integration of electrochemical double layer capacitor based carbonaceous materials (high power density) and pseudocapacitive based metal hydroxides/oxides or conducting polymers (high energy density). The envisioned three dimensional (3D) graphene foams are predominantly advantageous to extend potential applicability by offering a large active surface area and a highly conductive continuous porous network for fast charge transfer with decoration of nanosized pseudocapacitive materials. In this article, we review the latest methodologies and performance evaluation for several 3D graphene based metal oxides/hydroxides and conducting polymer electrodes with improved electrochemical properties for next-generation supercapacitors. The most recent research advancements of our and other groups in the field of 3D graphene based electrode materials for supercapacitors are discussed. To assess the studied materials fully, a careful interpretation and rigorous scrutiny of their electrochemical characteristics is essential. Auspiciously, both nano-structuration as well as confinement of metal hydroxides/oxides and conducting polymers onto a conducting porous 3D graphene matrix play a great role in improving the performance of electrodes mainly due to: (i) active material access over large surface area with fast charge transportation; (ii) synergetic effect of electric double layer and pseudocapacitive based charge storing.
4DCBCT-based motion modeling and 3D fluoroscopic image generation for lung cancer radiotherapy
NASA Astrophysics Data System (ADS)
Dhou, Salam; Hurwitz, Martina; Mishra, Pankaj; Berbeco, Ross; Lewis, John
2015-03-01
A method is developed to build patient-specific motion models based on 4DCBCT images taken at treatment time and use them to generate 3D time-varying images (referred to as 3D fluoroscopic images). Motion models are built by applying Principal Component Analysis (PCA) on the displacement vector fields (DVFs) estimated by performing deformable image registration on each phase of 4DCBCT relative to a reference phase. The resulting PCA coefficients are optimized iteratively by comparing 2D projections captured at treatment time with projections estimated using the motion model. The optimized coefficients are used to generate 3D fluoroscopic images. The method is evaluated using anthropomorphic physical and digital phantoms reproducing real patient trajectories. For physical phantom datasets, the average tumor localization error (TLE) and (95th percentile) in two datasets were 0.95 (2.2) mm. For digital phantoms assuming superior image quality of 4DCT and no anatomic or positioning disparities between 4DCT and treatment time, the average TLE and the image intensity error (IIE) in six datasets were smaller using 4DCT-based motion models. When simulating positioning disparities and tumor baseline shifts at treatment time compared to planning 4DCT, the average TLE (95th percentile) and IIE were 4.2 (5.4) mm and 0.15 using 4DCT-based models, while they were 1.2 (2.2) mm and 0.10 using 4DCBCT-based ones, respectively. 4DCBCT-based models were shown to perform better when there are positioning and tumor baseline shift uncertainties at treatment time. Thus, generating 3D fluoroscopic images based on 4DCBCT-based motion models can capture both inter- and intra- fraction anatomical changes during treatment.
Next-generation regenerative medicine: organogenesis from stem cells in 3D culture.
Sasai, Yoshiki
2013-05-02
The behavior of stem cells, when they work collectively, can be much more sophisticated than one might expect from their individual programming. This Perspective covers recent discoveries about the dynamic patterning and structural self-formation of complex organ buds in 3D stem cell culture, including the generation of various neuroectodermal and endodermal tissues. For some tissues, epithelial-mesenchymal interactions can also be manipulated in coculture to guide organogenesis. This new area of stem cell research-the spatiotemporal control of dynamic cellular interactions-will open a new avenue for next-generation regenerative medicine.
Modeling a Helical-coil Steam Generator in RELAP5-3D for the Next Generation Nuclear Plant
Nathan V. Hoffer; Piyush Sabharwall; Nolan A. Anderson
2011-01-01
Options for the primary heat transport loop heat exchangers for the Next Generation Nuclear Plant are currently being evaluated. A helical-coil steam generator is one heat exchanger design under consideration. Safety is an integral part of the helical-coil steam generator evaluation. Transient analysis plays a key role in evaluation of the steam generators safety. Using RELAP5-3D to model the helical-coil steam generator, a loss of pressure in the primary side of the steam generator is simulated. This report details the development of the steam generator model, the loss of pressure transient, and the response of the steam generator primary and secondary systems to the loss of primary pressure. Back ground on High Temperature Gas-cooled reactors, steam generators, the Next Generation Nuclear Plant is provided to increase the readers understanding of the material presented.
Lee, W H; Kim, T S; Kim, Andrew T; Lee, S Y
2008-01-01
Realistic finite element (FE) head models have been successfully applied to bioelectromagnetic problems due to a realistic representation of arbitrary head geometry with inclusion of anisotropic material properties. In this paper, we propose a new automatic FE mesh generation scheme to generate a diffusion tensor MRI (DT-MRI) white matter anisotropy content-adaptive FE head model. We term this kind of mesh as wMesh. With this meshing technique, the anisotropic electrical conductivities derived from DT-MRIs can be best incorporated into the model. The influence of the white matter anisotropy on the EEG forward solutions has been studied via our wMesh head models. The scalp potentials computed from the anisotropic wMesh models against those of the isotropic models have been compared. The results describe that there are substantial changes in the scalp electrical potentials between the isotropic and anisotropic models, indicating that the inclusion of the white matter anisotropy is critical for accurate computation of E/MEG forward and inverse solutions. This fully automatic anisotropy-adaptive wMesh meshing scheme could be useful for modeling of individual-specific FE head models with better incorporation of the white matter anisotropic property towards bioelectromagnetic imaging.
3D Spectrum of Equatorial Density Irregularities Generated from Observed 1D Spectra
NASA Astrophysics Data System (ADS)
Bust, G. S.; Rodrigues, F. S.; Psiake, M.; Kelley, M. C.; Roddy, P. A.
2009-12-01
ASTRA and Cornell University have a joint project underway to develop an inverse diffraction tomography algorithm suitable for a two-dimensional array of GPS receivers located in the equatorial region. A significant component of the research involves development of an accurate, realistic electro-magnetic propagation forward model that goes from the GPS satellites to the array of ground receivers. The forward model will be used to test the accuracy of the inverse diffraction tomography algorithm, help select the optimal method of doing the inversion, allow for comprehensive, sophisticated non-linear inversions, and help provide insight to the science that will result from the inversion analysis. The method of approach to the forward model includes a realistic 3D model of the electron density irregularities, arbitrary time-varying geometry between satellite and ground receiver array and multiple phase screens to allow for strong scattering. The focus of this talk is on the development of the 3D spectrum of the irregularities, and how the 3D spectrum can be generated from observed in-situ 1D spectra from rockets or satellites such C/NOFS. The C/NOFS satellite has an in-situ Plasma Langmuir Probe (PLP) sensor that is capable of measuring electron density fluctuations at sample rates of 512 Hz. Preliminary analysis has been performed on these fluctuations. Spectra have been calculated for a number of different altitudes and local times. Preliminary results are presented from this research and, assuming a power law form for the spectra, spectral indices are calculated. Given observed 1D spectra of the irregularities, a theoretical analysis will be presented that allows recovery of the 3D spectrum of irregularities from the observed 1D spectra. Preliminary calculations of such 3D spectra derived from the observed C/NOFS 1D spectra will be presented.
Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A.; Itoh, Munenari; Christiano, Angela M.
2015-01-01
The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes. PMID:26308443
Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A; Itoh, Munenari; Christiano, Angela M
2015-01-01
The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes.
Automation of three-dimensional structured mesh generation for turbomachinery blade passages
NASA Technical Reports Server (NTRS)
Ascoli, Edward P.; Prueger, George H.
1995-01-01
Hybrid tools have been developed which greatly reduce the time required to generate three-dimensional structured CFD meshes for turbomachinery blade passages. RAGGS, an existing Rockwell proprietary, general purpose mesh generation and visualization system, provides the starting point and framework for tool development. Utilities which manipulate and interface with RAGGS tools have been developed to (1) facilitate blade geometry inputs from point or CAD representations, (2) automate auxiliary surface creation, and (3) streamline and automate edge, surface, and subsequent volume mesh generation from minimal inputs. The emphasis of this approach has been to maintain all the functionality of the general purpose mesh generator while simultaneously eliminating the bulk of the repetitive and tediuos manual steps in the mesh generation process. Using this approach, mesh generation cycle times have been reduced from the order of days down to the order of hours.
NASA Astrophysics Data System (ADS)
Patchimpattapong, Apisit
This dissertation develops an expert system for generating an effective spatial mesh distribution for the discrete ordinates particle transport method in a parallel environment. This expert system consists of two main parts: (1) an algorithm for generating an effective mesh distribution in a serial environment, and (2) an algorithm for inference of an effective domain decomposition strategy for parallel computing. The mesh generation algorithm consists of four steps: creation of a geometric model as partitioned into coarse meshes, determination of an approximate flux shape, selection of appropriate differencing schemes, and generation of an effective fine mesh distribution. A geometric model was created using AutoCAD. A parallel code PENFC (Parallel Environment Neutral-Particle First Collision) has been developed to calculate an uncollided flux in a 3-D Cartesian geometry. The appropriate differencing schemes were selected based on the uncollided flux distribution using a least squares methodology. A menu-driven serial code PENXMSH has been developed to generate an effective spatial mesh distribution that preserves problem geometry and physics. The domain decomposition selection process involves evaluation of the four factors that affect parallel performance, which include number of processors and memory available per processor, load balance, granularity, and degree-of-coupling among processors. These factors are used to derive a parallel-performance-index that provides expected performance of a parallel algorithm depending on computing environment and resources. A large index indicates a high granularity algorithm with relatively low coupling among processors. This expert system has been successfully tested within the PENTRAN (Parallel Environment Neutral-Particle Transport) code system for simulating real-life shielding problems: the VENUS-3 experimental facility and the BWR core shroud.
Drag Prediction for the DLR-F4 Wing/Body using OVERFLOW and CFL3D on an Overset Mesh
NASA Technical Reports Server (NTRS)
Vassberg, John C.; Buning, Pieter G.; Rumsey, Christopher L.
2002-01-01
This paper reviews the importance of numerical drag prediction in an aircraft design environment. A chronicle of collaborations between the authors and colleagues is discussed. This retrospective provides a road-map which illustrates some of the actions taken in the past seven years in pursuit of accurate drag prediction. The advances made possible through these collaborations have changed the manner in which business is conducted during the design of all-new aircraft. The subject of this study is the DLR-F4 wing/body transonic model. Specifically, the work conducted herein was in support of the 1st CFD Drag Prediction Workshop, which was held in conjunction with the 19th Applied Aerodynamics Conference in Anaheim, CA during June, 2001. Comprehensive sets of OVERFLOW simulations were independently performed by several users on a variety of computational platforms. CFL3D was used on a limited basis for additional comparison on the same overset mesh. Drag polars based on this database were constructed with a CFD-to-Test correction applied and compared with test data from three facilities. These comparisons show that the predicted drag polars fall inside the scatter band of the test data, at least for pre-buffet conditions. This places the corrected drag levels within 1% of the averaged experimental values. At the design point, the OVERFLOW and CFL3D drag predictions are within 1-2% of each other. In addition, drag-rise characteristics and a boundary of drag-divergence Mach number are presented.
Performance of an improved first generation optical CT scanner for 3D dosimetry
NASA Astrophysics Data System (ADS)
Qian, Xin; Adamovics, John; Wuu, Cheng-Shie
2013-12-01
Performance analysis of a modified 3D dosimetry optical scanner based on the first generation optical CT scanner OCTOPUS is presented. The system consists of PRESAGE™ dosimeters, the modified 3D scanner, and a new developed in-house user control panel written in Labview program which provides more flexibility to optimize mechanical control and data acquisition technique. The total scanning time has been significantly reduced from initial 8 h to ∼2 h by using the modified scanner. The functional performance of the modified scanner has been evaluated in terms of the mechanical integrity uncertainty of the data acquisition process. Optical density distribution comparison between the modified scanner, OCTOPUS and the treatment plan system has been studied. It has been demonstrated that the agreement between the modified scanner and treatment plans is comparable with that between the OCTOPUS and treatment plans.
Automatic Generation of 3D Caricatures Based on Artistic Deformation Styles.
Clarke, Lyndsey; Chen, Min; Mora, Benjamin
2011-06-01
Caricatures are a form of humorous visual art, usually created by skilled artists for the intention of amusement and entertainment. In this paper, we present a novel approach for automatic generation of digital caricatures from facial photographs, which capture artistic deformation styles from hand-drawn caricatures. We introduced a pseudo stress-strain model to encode the parameters of an artistic deformation style using "virtual" physical and material properties. We have also developed a software system for performing the caricaturistic deformation in 3D which eliminates the undesirable artifacts in 2D caricaturization. We employed a Multilevel Free-Form Deformation (MFFD) technique to optimize a 3D head model reconstructed from an input facial photograph, and for controlling the caricaturistic deformation. Our results demonstrated the effectiveness and usability of the proposed approach, which allows ordinary users to apply the captured and stored deformation styles to a variety of facial photographs.
Performance of an improved first generation optical CT scanner for 3D dosimetry.
Qian, Xin; Adamovics, John; Wuu, Cheng-Shie
2013-12-21
Performance analysis of a modified 3D dosimetry optical scanner based on the first generation optical CT scanner OCTOPUS is presented. The system consists of PRESAGE dosimeters, the modified 3D scanner, and a new developed in-house user control panel written in Labview program which provides more flexibility to optimize mechanical control and data acquisition technique. The total scanning time has been significantly reduced from initial 8 h to ∼2 h by using the modified scanner. The functional performance of the modified scanner has been evaluated in terms of the mechanical integrity uncertainty of the data acquisition process. Optical density distribution comparison between the modified scanner, OCTOPUS and the treatment plan system has been studied. It has been demonstrated that the agreement between the modified scanner and treatment plans is comparable with that between the OCTOPUS and treatment plans.
Ball, A D; Job, P A; Walker, A E L
2017-08-01
The method we present here uses a scanning electron microscope programmed via macros to automatically capture dozens of images at suitable angles to generate accurate, detailed three-dimensional (3D) surface models with micron-scale resolution. We demonstrate that it is possible to use these Scanning Electron Microscope (SEM) images in conjunction with commercially available software originally developed for photogrammetry reconstructions from Digital Single Lens Reflex (DSLR) cameras and to reconstruct 3D models of the specimen. These 3D models can then be exported as polygon meshes and eventually 3D printed. This technique offers the potential to obtain data suitable to reconstruct very tiny features (e.g. diatoms, butterfly scales and mineral fabrics) at nanometre resolution. Ultimately, we foresee this as being a useful tool for better understanding spatial relationships at very high resolution. However, our motivation is also to use it to produce 3D models to be used in public outreach events and exhibitions, especially for the blind or partially sighted. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.
Advances in Parallelization for Large Scale Oct-Tree Mesh Generation
NASA Technical Reports Server (NTRS)
O'Connell, Matthew; Karman, Steve L.
2015-01-01
Despite great advancements in the parallelization of numerical simulation codes over the last 20 years, it is still common to perform grid generation in serial. Generating large scale grids in serial often requires using special "grid generation" compute machines that can have more than ten times the memory of average machines. While some parallel mesh generation techniques have been proposed, generating very large meshes for LES or aeroacoustic simulations is still a challenging problem. An automated method for the parallel generation of very large scale off-body hierarchical meshes is presented here. This work enables large scale parallel generation of off-body meshes by using a novel combination of parallel grid generation techniques and a hybrid "top down" and "bottom up" oct-tree method. Meshes are generated using hardware commonly found in parallel compute clusters. The capability to generate very large meshes is demonstrated by the generation of off-body meshes surrounding complex aerospace geometries. Results are shown including a one billion cell mesh generated around a Predator Unmanned Aerial Vehicle geometry, which was generated on 64 processors in under 45 minutes.
Using Openstreetmap Data to Generate Building Models with Their Inner Structures for 3d Maps
NASA Astrophysics Data System (ADS)
Wang, Z.; Zipf, A.
2017-09-01
With the development of Web 2.0, more and more data related to indoor environments has been collected within the volunteered geographic information (VGI) framework, which creates a need for construction of indoor environments from VGI. In this study, we focus on generating 3D building models from OpenStreetMap (OSM) data, and provide an approach to support construction and visualization of indoor environments on 3D maps. In this paper, we present an algorithm which can extract building information from OSM data, and can construct building structures as well as inner building components (e.g., doors, rooms, and windows). A web application is built to support the processing and visualization of the building models on a 3D map. We test our approach with an indoor dataset collected from the field. The results show the feasibility of our approach and its potentials to provide support for a wide range of applications, such as indoor and outdoor navigation, urban planning, and incident management.
Generating 3D depletion distribution in an achromatic single-channel monolithic system
NASA Astrophysics Data System (ADS)
Fallet, Clement; Lindberg, Arvid; Sirat, Gabriel Y.
2016-02-01
Recent developments have shown that conical diffraction by a biaxial crystal can create a vortex beam for use in 2D STED microscopy. It has been shown that this concept can be extended and also generate the depletion distributions used for 3D STED microscopy. A single beam passes through a biaxial crystal that creates two co-propagating, co-localized beams; the first one is used for lateral depletion, and the other one for axial depletion. The two beams are crossed-polarized and thus do not interfere. We will show that the 3D distribution can be made achromatic, i.e. several depletion wavelengths can travel through a common path and still be shaped into the appropriate pattern by optimizing the geometry of the system. This system enables true one-channel 3D depletion at multiple wavelengths ranging from 580nm to 770nm, thus covering most of the conventional depletion wavelengths currently used. Preliminary results of depletion PSFs will be presented and the advantages and limitations of this system will be discussed as well as the experimental considerations required to successfully obtain the desired PSFs.
Kozhevnikov, Maria; Dhond, Rupali P.
2012-01-01
Most research on three-dimensional (3D) visual-spatial processing has been conducted using traditional non-immersive 2D displays. Here we investigated how individuals generate and transform mental images within 3D immersive (3DI) virtual environments, in which the viewers perceive themselves as being surrounded by a 3D world. In Experiment 1, we compared participants’ performance on the Shepard and Metzler (1971) mental rotation (MR) task across the following three types of visual presentation environments; traditional 2D non-immersive (2DNI), 3D non-immersive (3DNI – anaglyphic glasses), and 3DI (head mounted display with position and head orientation tracking). In Experiment 2, we examined how the use of different backgrounds affected MR processes within the 3DI environment. In Experiment 3, we compared electroencephalogram data recorded while participants were mentally rotating visual-spatial images presented in 3DI vs. 2DNI environments. Overall, the findings of the three experiments suggest that visual-spatial processing is different in immersive and non-immersive environments, and that immersive environments may require different image encoding and transformation strategies than the two other non-immersive environments. Specifically, in a non-immersive environment, participants may utilize a scene-based frame of reference and allocentric encoding whereas immersive environments may encourage the use of a viewer-centered frame of reference and egocentric encoding. These findings also suggest that MR performed in laboratory conditions using a traditional 2D computer screen may not reflect spatial processing as it would occur in the real world. PMID:22908003
Inflight performance of a second-generation photon-counting 3D imaging lidar
NASA Astrophysics Data System (ADS)
Degnan, John; Machan, Roman; Leventhal, Ed; Lawrence, David; Jodor, Gabriel; Field, Christopher
2008-04-01
Sigma Space Corporation has recently developed a compact 3D imaging and polarimetric lidar suitable for use in a small aircraft or mini-UAV. A frequency-doubled Nd:YAG microchip laser generates 6 microjoule, subnanosecond pulses at fire rates up to 22 kHz. A Diffractive Optical Element (DOE) breaks the 532 nm beam into a 10x10 array of Gaussian beamlets, each containing about 1 mW of laser power (50 nJ @ 20 kHz). The reflected radiation in each beamlet is imaged by the receive optics onto individual pixels of a high efficiency, 10x10 pixel, multistop detector. Each pixel is then input to one channel of a 100 channel, multistop timer demonstrated to have a 93 picosecond timing (1.4 cm range) resolution and an event recovery time of only 1.6 nsec. Thus, each green laser pulse produces a 100 pixel volumetric 3D image. The residual infrared energy at 1064 nm is used for polarimetry. The scan pattern and frequency of a dual wedge optical scanner, synchronized to the laser fire rate, are tailored to provide contiguous coverage of a ground scene in a single overflight. In both rooftop and preliminary flight tests, the lidar has produced high spatial resolution 3D images of terrain, buildings, tree structures, power lines, and bridges with a data acquisition rate up to 2.2 million multistop 3D pixels per second. Current tests are aimed at defining the lidar's ability to image through water columns and tree canopies.
Automatic generation of dynamic 3D models for medical segmentation tasks
NASA Astrophysics Data System (ADS)
Dornheim, Lars; Dornheim, Jana; Tönnies, Klaus D.
2006-03-01
Models of geometry or appearance of three-dimensional objects may be used for locating and specifying object instances in 3D image data. Such models are necessary for segmentation if the object to be segmented is not separable based on image information only. They provide a-priori knowledge about the expected shape of the target structure. The success of such a segmentation task depends on the incorporated model knowledge. We present an automatic method to generate such a model for a given target structure. This knowledge is created in the form of a 3D Stable Mass-Spring Model (SMSM) and can be computed from a single sample segmentation. The model is built from different image features using a bottom-up strategy, which allows for different levels of model abstraction. We show the adequacy of the generated models in two practical medical applications: the anatomical segmentation of the left ventricle in myocardial perfusion SPECT, and the segmentation of the thyroid cartilage of the larynx in CT datasets. In both cases, the model generation was performed in a few seconds.
Monte Carlo generators for studies of the 3D structure of the nucleon
Avakian, Harut; D'Alesio, U.; Murgia, F.
2015-01-23
In this study, extraction of transverse momentum and space distributions of partons from measurements of spin and azimuthal asymmetries requires development of a self consistent analysis framework, accounting for evolution effects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.
GPU accelerated generation of digitally reconstructed radiographs for 2-D/3-D image registration.
Dorgham, Osama M; Laycock, Stephen D; Fisher, Mark H
2012-09-01
Recent advances in programming languages for graphics processing units (GPUs) provide developers with a convenient way of implementing applications which can be executed on the CPU and GPU interchangeably. GPUs are becoming relatively cheap, powerful, and widely available hardware components, which can be used to perform intensive calculations. The last decade of hardware performance developments shows that GPU-based computation is progressing significantly faster than CPU-based computation, particularly if one considers the execution of highly parallelisable algorithms. Future predictions illustrate that this trend is likely to continue. In this paper, we introduce a way of accelerating 2-D/3-D image registration by developing a hybrid system which executes on the CPU and utilizes the GPU for parallelizing the generation of digitally reconstructed radiographs (DRRs). Based on the advancements of the GPU over the CPU, it is timely to exploit the benefits of many-core GPU technology by developing algorithms for DRR generation. Although some previous work has investigated the rendering of DRRs using the GPU, this paper investigates approximations which reduce the computational overhead while still maintaining a quality consistent with that needed for 2-D/3-D registration with sufficient accuracy to be clinically acceptable in certain applications of radiation oncology. Furthermore, by comparing implementations of 2-D/3-D registration on the CPU and GPU, we investigate current performance and propose an optimal framework for PC implementations addressing the rigid registration problem. Using this framework, we are able to render DRR images from a 256×256×133 CT volume in ~24 ms using an NVidia GeForce 8800 GTX and in ~2 ms using NVidia GeForce GTX 580. In addition to applications requiring fast automatic patient setup, these levels of performance suggest image-guided radiation therapy at video frame rates is technically feasible using relatively low cost PC
Zhang, Zhiwei; Tian, Jiwei; Qiu, Bo; Zhao, Wei; Chang, Ping; Wu, Dexing; Wan, Xiuquan
2016-01-01
Oceanic mesoscale eddies with horizontal scales of 50–300 km are the most energetic form of flows in the ocean. They are the oceanic analogues of atmospheric storms and are effective transporters of heat, nutrients, dissolved carbon, and other biochemical materials in the ocean. Although oceanic eddies have been ubiquitously observed in the world oceans since 1960s, our understanding of their three-dimensional (3D) structure, generation, and dissipation remains fragmentary due to lack of systematic full water-depth measurements. To bridge this knowledge gap, we designed and conducted a multi-months field campaign, called the South China Sea Mesoscale Eddy Experiment (S-MEE), in the northern South China Sea in 2013/2014. The S-MEE for the first time captured full-depth 3D structures of an anticyclonic and cyclonic eddy pair, which are characterized by a distinct vertical tilt of their axes. By observing the eddy evolution at an upstream versus downstream location and conducting an eddy energy budget analysis, the authors further proposed that generation of submesoscale motions most likely constitutes the dominant dissipation mechanism for the observed eddies. PMID:27074710
NASA Astrophysics Data System (ADS)
Zhang, Zhiwei; Tian, Jiwei; Qiu, Bo; Zhao, Wei; Chang, Ping; Wu, Dexing; Wan, Xiuquan
2016-04-01
Oceanic mesoscale eddies with horizontal scales of 50–300 km are the most energetic form of flows in the ocean. They are the oceanic analogues of atmospheric storms and are effective transporters of heat, nutrients, dissolved carbon, and other biochemical materials in the ocean. Although oceanic eddies have been ubiquitously observed in the world oceans since 1960s, our understanding of their three-dimensional (3D) structure, generation, and dissipation remains fragmentary due to lack of systematic full water-depth measurements. To bridge this knowledge gap, we designed and conducted a multi-months field campaign, called the South China Sea Mesoscale Eddy Experiment (S-MEE), in the northern South China Sea in 2013/2014. The S-MEE for the first time captured full-depth 3D structures of an anticyclonic and cyclonic eddy pair, which are characterized by a distinct vertical tilt of their axes. By observing the eddy evolution at an upstream versus downstream location and conducting an eddy energy budget analysis, the authors further proposed that generation of submesoscale motions most likely constitutes the dominant dissipation mechanism for the observed eddies.
Zhang, Zhiwei; Tian, Jiwei; Qiu, Bo; Zhao, Wei; Chang, Ping; Wu, Dexing; Wan, Xiuquan
2016-04-14
Oceanic mesoscale eddies with horizontal scales of 50-300 km are the most energetic form of flows in the ocean. They are the oceanic analogues of atmospheric storms and are effective transporters of heat, nutrients, dissolved carbon, and other biochemical materials in the ocean. Although oceanic eddies have been ubiquitously observed in the world oceans since 1960s, our understanding of their three-dimensional (3D) structure, generation, and dissipation remains fragmentary due to lack of systematic full water-depth measurements. To bridge this knowledge gap, we designed and conducted a multi-months field campaign, called the South China Sea Mesoscale Eddy Experiment (S-MEE), in the northern South China Sea in 2013/2014. The S-MEE for the first time captured full-depth 3D structures of an anticyclonic and cyclonic eddy pair, which are characterized by a distinct vertical tilt of their axes. By observing the eddy evolution at an upstream versus downstream location and conducting an eddy energy budget analysis, the authors further proposed that generation of submesoscale motions most likely constitutes the dominant dissipation mechanism for the observed eddies.
A second generation of physical anthropomorphic 3D breast phantoms based on human subject data
NASA Astrophysics Data System (ADS)
Nolte, Adam; Kiarashi, Nooshin; Samei, Ehsan; Segars, W. P.; Lo, Joseph Y.
2014-03-01
Previous fabrication of anthropomorphic breast phantoms has demonstrated their viability as a model for 2D (mammography) and 3D (tomosynthesis) breast imaging systems. Further development of these models will be essential for the evaluation of breast x-ray systems. There is also the potential to use them as the ground truth in virtual clinical trials. The first generation of phantoms was segmented from human subject dedicated breast computed tomography data and fabricated into physical models using highresolution 3D printing. Two variations were made. The first was a multi-material model (doublet) printed with two photopolymers to represent glandular and adipose tissues with the greatest physical contrast available, mimicking 75% and 35% glandular tissue. The second model was printed with a single 75% glandular equivalent photopolymer (singlet) to represent glandular tissue, which can be filled independently with an adipose-equivalent material such as oil. For this study, we have focused on improving the latter, the singlet phantom. First, the temporary oil filler has been replaced with a permanent adipose-equivalent urethane-based polymer. This offers more realistic contrast as compared to the multi-material approach at the expense of air bubbles and pockets that form during the filling process. Second, microcalcification clusters have been included in the singlet model via crushed eggshells, which have very similar chemical composition to calcifications in vivo. The results from these new prototypes demonstrate significant improvement over the first generation of anthropomorphic physical phantoms.
NASA Technical Reports Server (NTRS)
Parikh, Paresh; Pirzadeh, Shahyar; Loehner, Rainald
1990-01-01
A set of computer programs for 3-D unstructured grid generation, fluid flow calculations, and flow field visualization was developed. The grid generation program, called VGRID3D, generates grids over complex configurations using the advancing front method. In this method, the point and element generation is accomplished simultaneously, VPLOT3D is an interactive, menudriven pre- and post-processor graphics program for interpolation and display of unstructured grid data. The flow solver, VFLOW3D, is an Euler equation solver based on an explicit, two-step, Taylor-Galerkin algorithm which uses the Flux Corrected Transport (FCT) concept for a wriggle-free solution. Using these programs, increasingly complex 3-D configurations of interest to aerospace community were gridded including a complete Space Transportation System comprised of the space-shuttle orbitor, the solid-rocket boosters, and the external tank. Flow solutions were obtained on various configurations in subsonic, transonic, and supersonic flow regimes.
Efficient and Robust Cartesian Mesh Generation for Building-Cube Method
NASA Astrophysics Data System (ADS)
Ishida, Takashi; Takahashi, Shun; Nakahashi, Kazuhiro
In this study, an efficient and robust Cartesian mesh generation method for Building-Cube Method (BCM) is proposed. It can handle “dirty” geometry data whose surface has cracks, overlaps, and reverse of triangle. BCM mesh generation is implemented by two procedures; cube generation and cell generation in each cube. The cell generation procedure in this study is managed in each cube individually, and parallelized by OpenMP. Efficiency of the parallelized BCM mesh generation is demonstrated for several three-dimensional test cases using a multi-core PC.
Composite structured mesh generation with automatic domain decomposition in complex geometries
USDA-ARS?s Scientific Manuscript database
This paper presents a novel automatic domain decomposition method to generate quality composite structured meshes in complex domains with arbitrary shapes, in which quality structured mesh generation still remains a challenge. The proposed decomposition algorithm is based on the analysis of an initi...
3D printer generated thorax phantom with mobile tumor for radiation dosimetry.
Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B
2015-07-01
This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor's trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between
3D printer generated thorax phantom with mobile tumor for radiation dosimetry
NASA Astrophysics Data System (ADS)
Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B.
2015-07-01
This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor's trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between
3D printer generated thorax phantom with mobile tumor for radiation dosimetry
Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B.
2015-07-15
This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor’s trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between
Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Grasso, Salvatore; Sakka, Yoshio; Tok, Alfred; Su, Liap Tat; Bosman, Michael; Ma, Jan
2012-02-01
Boron carbide B4C powders were subject to reactive spark plasma sintering (also known as field assisted sintering, pulsed current sintering or plasma assisted sintering) under nitrogen atmosphere. For an optimum hexagonal BN (h-BN) content estimated from X-ray diffraction measurements at approximately 0.4 wt%, the as-prepared BaCb-(BxOy/BN) ceramic shows values of Berkovich and Vickers hardness of 56.7 +/- 3.1 GPa and 39.3 +/- 7.6 GPa, respectively. These values are higher than for the vacuum SPS processed B4C pristine sample and the h-BN -mechanically-added samples. XRD and electronic microscopy data suggest that in the samples produced by reactive SPS in N2 atmosphere, and containing an estimated amount of 0.3-1.5% h-BN, the crystallite size of the boron carbide grains is decreasing with the increasing amount of N2, while for the newly formed lamellar h-BN the crystallite size is almost constant (approximately 30-50 nm). BN is located at the grain boundaries between the boron carbide grains and it is wrapped and intercalated by a thin layer of boron oxide. BxOy/BN forms a fine and continuous 3D mesh-like structure that is a possible reason for good mechanical properties.
Yeom, Han-Ju; Park, Jae-Hyeung
2016-08-22
We propose a method to obtain a computer-generated hologram that renders reflectance distributions of individual mesh surfaces of three-dimensional objects. Unlike previous methods which find phase distribution inside each mesh, the proposed method performs convolution of angular spectrum of the mesh to obtain desired reflectance distribution. Manipulation in the angular spectrum domain enables its application to fully-analytic mesh based computer generated hologram, removing the necessity for resampling of the spatial frequency grid. It is also computationally inexpensive as the convolution can be performed efficiently using Fourier transform. In this paper, we present principle, error analysis, simulation, and experimental verification results of the proposed method.
View generation for 3D-TV using image reconstruction from irregularly spaced samples
NASA Astrophysics Data System (ADS)
Vázquez, Carlos
2007-02-01
Three-dimensional television (3D-TV) will become the next big step in the development of advanced TV systems. One of the major challenges for the deployment of 3D-TV systems is the diversity of display technologies and the high cost of capturing multi-view content. Depth image-based rendering (DIBR) has been identified as a key technology for the generation of new views for stereoscopic and multi-view displays from a small number of views captured and transmitted. We propose a disparity compensation method for DIBR that does not require spatial interpolation of the disparity map. We use a forward-mapping disparity compensation with real precision. The proposed method deals with the irregularly sampled image resulting from this disparity compensation process by applying a re-sampling algorithm based on a bi-cubic spline function space that produces smooth images. The fact that no approximation is made on the position of the samples implies that geometrical distortions in the final images due to approximations in sample positions are minimized. We also paid attention to the occlusion problem. Our algorithm detects the occluded regions in the newly generated images and uses simple depth-aware inpainting techniques to fill the gaps created by newly exposed areas. We tested the proposed method in the context of generation of views needed for viewing on SynthaGram TM auto-stereoscopic displays. We used as input either a 2D image plus a depth map or a stereoscopic pair with the associated disparity map. Our results show that this technique provides high quality images to be viewed on different display technologies such as stereoscopic viewing with shutter glasses (two views) and lenticular auto-stereoscopic displays (nine views).
Wang, Junchen; Suenaga, Hideyuki; Liao, Hongen; Hoshi, Kazuto; Yang, Liangjing; Kobayashi, Etsuko; Sakuma, Ichiro
2015-03-01
Autostereoscopic 3D image overlay for augmented reality (AR) based surgical navigation has been studied and reported many times. For the purpose of surgical overlay, the 3D image is expected to have the same geometric shape as the original organ, and can be transformed to a specified location for image overlay. However, how to generate a 3D image with high geometric fidelity and quantitative evaluation of 3D image's geometric accuracy have not been addressed. This paper proposes a graphics processing unit (GPU) based computer-generated integral imaging pipeline for real-time autostereoscopic 3D display, and an automatic closed-loop 3D image calibration paradigm for displaying undistorted 3D images. Based on the proposed methods, a novel AR device for 3D image surgical overlay is presented, which mainly consists of a 3D display, an AR window, a stereo camera for 3D measurement, and a workstation for information processing. The evaluation on the 3D image rendering performance with 2560×1600 elemental image resolution shows the rendering speeds of 50-60 frames per second (fps) for surface models, and 5-8 fps for large medical volumes. The evaluation of the undistorted 3D image after the calibration yields sub-millimeter geometric accuracy. A phantom experiment simulating oral and maxillofacial surgery was also performed to evaluate the proposed AR overlay device in terms of the image registration accuracy, 3D image overlay accuracy, and the visual effects of the overlay. The experimental results show satisfactory image registration and image overlay accuracy, and confirm the system usability.
NASA Astrophysics Data System (ADS)
Palevicius, Arvydas; Grigaliunas, Viktoras; Janusas, Giedrius; Palevicius, Paulius; Sakalys, Rokas
2016-04-01
The main focus of the paper is the development of technological route of the production of complex 3D microstructure, from designing it by the method of computer generated holography till its physical 3D patterning by exploiting the process of electron beam lithography and thermal replication which is used for biomedical application. A phase data of a complex 3D microstructure was generated by using Gerchberg-Saxton algorithm which later was used to produce a computer generated hologram. Physical implementation of microstructure was done using a single layer polymethyl methacrylate (PMMA) as a basis for 3D microstructure, which was exposed using e-beam lithography system e-Line and replicated, using high frequency vibration. Manufactured 3D microstructure is used for designing micro sensor for biomedical applications.
Hambach, Lothar; Buser, Andreas; Vermeij, Marcel; Pouw, Nadine; van der Kwast, Theo; Goulmy, Els
2016-01-01
Cellular immunotherapy targeting human tumor antigens is a promising strategy to treat solid tumors. Yet clinical results of cellular immunotherapy are disappointing. Moreover, the currently available in vitro human tumor models are not designed to study the optimization of T-cell therapies of solid tumors. Here, we describe a novel assay for multiparametric in situ analysis of therapeutic effects on individual human three-dimensional (3D) tumors. In this assay, tumors of several millimeter diameter are generated from human cancer cell lines of different tumor entities in a collagen type I microenvironment. A newly developed approach for efficient morphological analysis reveals that these in vitro tumors resemble many characteristics of the corresponding clinical cancers such as histological features, immunohistochemical staining patterns, distinct tumor growth compartments and heterogeneous protein expression. To assess the response to therapy with tumor antigen specific T-cells, standardized protocols are described to determine T-cell infiltration and tumor destruction by monitoring soluble factors and tumor growth. Human tumors engineered in 3D collagen scaffolds are excellent in vitro surrogates for avascular tumor stages allowing integrated analyses of the antitumor efficacy of cancer specific immunotherapy in situ.
NASA Astrophysics Data System (ADS)
Andreazzoli, Massimiliano; Angeloni, Debora; Broccoli, Vania; Demontis, Gian C.
2017-04-01
Space is a challenging environment for the human body, due to the combined effects of reduced gravity (microgravity) and cosmic radiation. Known effects of microgravity range from the blood redistribution that affects the cardiovascular system and the eye to muscle wasting, bone loss, anemia and immune depression. About cosmic radiation, the shielding provided by the spaceship hull is far less efficient than that afforded at ground level by the combined effects of the Earth atmosphere and magnetic field. The eye and its nervous layer (the retina) are affected by both microgravity and heavy ions exposure. Considering the importance of sight for long-term manned flights, visual research aimed at devising measures to protect the eye from environmental conditions of the outer space represents a special challenge to meet. In this review we focus on the impact of microgravity on embryonic development, discussing the roles of mechanical forces in the context of the neutral buoyancy the embryo experiences in the womb. At variance with its adverse effects on the adult human body, simulated microgravity may provide a unique tool for understanding the biomechanical events involved in the development and assembly in vitro of three-dimensional (3D) ocular tissues. Prospective benefits are the development of novel safety measures to protect the human eye from cosmic radiation in microgravity during long-term manned spaceflights in the outer space, as well as the generation of human 3D-retinas with its supporting structures to develop innovative and effective therapeutic options for degenerative eye diseases.
NASA Astrophysics Data System (ADS)
Dahdouh, S.; Varsier, N.; Serrurier, A.; De la Plata, J.-P.; Anquez, J.; Angelini, E. D.; Wiart, J.; Bloch, I.
2014-08-01
Fetal dosimetry studies require the development of accurate numerical 3D models of the pregnant woman and the fetus. This paper proposes a 3D articulated fetal growth model covering the main phases of pregnancy and a pregnant woman model combining the utero-fetal structures and a deformable non-pregnant woman body envelope. The structures of interest were automatically or semi-automatically (depending on the stage of pregnancy) segmented from a database of images and surface meshes were generated. By interpolating linearly between fetal structures, each one can be generated at any age and in any position. A method is also described to insert the utero-fetal structures in the maternal body. A validation of the fetal models is proposed, comparing a set of biometric measurements to medical reference charts. The usability of the pregnant woman model in dosimetry studies is also investigated, with respect to the influence of the abdominal fat layer.
3D numerical investigation on landslide generated tsunamis around a conical island
NASA Astrophysics Data System (ADS)
Montagna, Francesca; Bellotti, Giorgio
2010-05-01
This paper presents numerical computations of tsunamis generated by subaerial and submerged landslides falling along the flank of a conical island. The study is inspired by the tsunamis that on 30th December 2002 attacked the coast of the volcanic island of Stromboli (South Tyrrhenian sea, Italy). In particular this paper analyzes the important feature of the lateral spreading of landside generated tsunamis and the associated flooding hazard. The numerical model used in this study is the full three dimensional commercial code FLOW-3D. The model has already been successfully used (Choi et al., 2007; 2008; Chopakatla et al, 2008) to study the interaction of waves and structures. In the simulations carried out in this work a particular feature of the code has been employed: the GMO (General Moving Object) algorithm. It allows to reproduce the interaction between moving objects, as a landslide, and the water. FLOW-3D has been firstly validated using available 3D experiments reproducing tsunamis generated by landslides at the flank of a conical island. The experiments have been carried out in the LIC laboratory of the Polytechnic of Bari, Italy (Di Risio et al., 2009). Numerical and experimental time series of run-up and sea level recorded at gauges located at the flanks of the island and offshore have been successfully compared. This analysis shows that the model can accurately represent the generation, the propagation and the inundation of landslide generated tsunamis and suggests the use of the numerical model as a tool for preparing inundation maps. At the conference we will present the validation of the model and parametric analyses aimed to investigate how wave properties depend on the landslide kinematic and on further parameters such as the landslide volume and shape, as well as the radius of the island. The expected final results of the research are precomputed inundation maps that depend on the characteristics of the landslide and of the island. Finally we
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1984-05-01
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Kennedy, T.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories, and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1993-11-30
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-d Finite Element Code Postprocessor
Whirley, R.G.
1991-05-01
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-d Finite Element Code Postprocessor
Whirley, R.G.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
TAURUS. 3-D Finite Element Code Postprocessor
Whirley, R.G.
1992-03-03
TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.
Design Curve Generation for 3D SiC Fiber Architecture
NASA Technical Reports Server (NTRS)
Lang, Jerry; Dicarlo, James A.
2014-01-01
The design tool provides design curves that allow a simple and quick way to examine multiple factors that can influence the processing and key properties of the preforms and their final SiC-reinforced ceramic composites without over obligating financial capital for the fabricating of materials. Tool predictions for process and fiber fraction properties have been validated for a HNS 3D preform.The virtualization aspect of the tool will be used to provide a quick generation of solid models with actual fiber paths for finite element evaluation to predict mechanical and thermal properties of proposed composites as well as mechanical displacement behavior due to creep and stress relaxation to study load sharing characteristic between constitutes for better performance.Tool predictions for the fiber controlled properties of the SiCSiC CMC fabricated from the HNS preforms will be valuated and up-graded from the measurements on these CMC
NASA Astrophysics Data System (ADS)
Boerstoel, J. W.
1986-08-01
Aproaches to grid generation are analyzed. A grid-generation procedure for complex aircraft configurations could be based on a combination of three subprocesses: decomposition of the flow domain into 100 hexahedronal blocks; trilinear transfinite interpolation to generate initial grid point distributions; and elliptic mesh-size tuning and smoothing. To get insight into this procedure, mathematical models of the subprocesses were worked out. The results of the analysis are technical concepts required or desirable in the grid-generation procedure.
Recent progress on fully analytic mesh based computer-generated holography
NASA Astrophysics Data System (ADS)
Park, Jae-Hyeung
2016-10-01
Computer generated holography plays a main role in the contents generation for holographic displays and digital archiving of three-dimensional objects. The fully analytic mesh based computer generated holography finds exact complex optical field for each triangular mesh of the three-dimensional objects for given sampling interval in the hologram plane without any approximation, enhancing the quality of the reconstruction. The mesh based processing rather than conventional point based one makes it compatible with most computer graphics techniques and efficient especially for large objects. In this paper, we present a few recent progress on fully analytic mesh based computer generated holography techniques including the dark line artifact removal, continuous shading of each mesh surface, the implementation of the angular reflectance distribution of the object surface and application of the texture map.
Carbon nanotubes leading the way forward in new generation 3D tissue engineering.
Hopley, Erin Leigh; Salmasi, Shima; Kalaskar, Deepak M; Seifalian, Alexander M
2014-01-01
Statistics from the NHS Blood and Transplant Annual Review show that total organ transplants have increased to 4213 in 2012, while the number of people waiting to receive an organ rose to 7613 that same year. Human donors as the origin of transplanted organs no longer meet the ever-increasing demand, and so interest has shifted to synthetic organ genesis as a form of supply. This focus has given rise to new generation tissue and organ engineering, in the hope of one day designing 3D organs in vitro. While research in this field has been conducted for several decades, leading to the first synthetic trachea transplant in 2011, scaffold design for optimising complex tissue growth is still underexplored and underdeveloped. This is mostly the result of the complexity required in scaffolds, as they need to mimic the cells' native extracellular matrix. This is an intricate nanostructured environment that provides cells with physical and chemical stimuli for optimum cell attachment, proliferation and differentiation. Carbon nanotubes are a popular addition to synthetic scaffolds and have already begun to revolutionise regenerative medicine. Discovered in 1991, these are traditionally used in various areas of engineering and technology; however, due to their excellent mechanical, chemical and electrical properties their potential is now being explored in areas of drug delivery, in vivo biosensor application and tissue engineering. The incorporation of CNTs into polymer scaffolds displays a variety of structural and chemical enhancements, some of which include: increased scaffold strength and flexibility, improved biocompatibility, reduction in cancerous cell division, induction of angiogenesis, reduced thrombosis, and manipulation of gene expression in developing cells. Moreover CNTs' tensile properties open doors for dynamic scaffold design, while their thermal and electrical properties provide opportunities for the development of neural, bone and cardiac tissue constructs
NASA Astrophysics Data System (ADS)
McFall, B. C.; Fritz, H. M.; Horrillo, J. J.; Mohammed, F.
2014-12-01
Landslide generated tsunamis such as Lituya Bay, Alaska 1958 account for some of highest recorded tsunami runup heights. Source and runup scenarios based on real world events are physically modeled using generalized Froude similarity in the three dimensional NEES tsunami wave basin at Oregon State University. A novel pneumatic landslide tsunami generator (LTG) was deployed to simulate landslides with varying geometry and kinematics. The bathymetric and topographic scenarios tested with the LTG are the basin-wide propagation and runup, fjord, curved headland fjord and a conical island setting representing a landslide off an island or a volcano flank collapse. The LTG consists of a sliding box filled with 1,350 kg of landslide material which is accelerated by pneumatic pistons down slope. Two different landslide materials are used to study the granulometry effects: naturally rounded river gravel and cobble mixtures. Water surface elevations are recorded by an array of resistance wave gauges. The landslide deformation is measured from above and underwater camera recordings. The landslide deposit is measured on the basin floor with a multiple transducer acoustic array (MTA). Landslide surface reconstruction and kinematics are determined with a stereo particle image velocimetry (PIV) system. Wave runup is recorded with resistance wave gauges along the slope and verified with video image processing. The measured landslide and wave parameters are compared between the planar hill slope used in various scenarios and the convex hill slope of the conical island. The energy conversion rates from the landslide motion to the wave train is quantified for the planar and convex hill slopes. The wave runup data on the opposing headland is analyzed and evaluated with wave theories. The measured landslide and tsunami data serve to validate and advance three-dimensional numerical landslide tsunami prediction models. Two 3D Navier-Stokes models were tested, the commercial code FLOW-3D
PARC3D calculations of the F/A-18A HARV inlet vortex generators
NASA Technical Reports Server (NTRS)
Podleski, Steve D.
1995-01-01
NASA Lewis Research Center is currently engaged in a research effort as a team member of the High Alpha Technology Program within the NASA agency. This program uses a specially-equipped F/A-18A aircraft called the High Alpha Research Vehicle (HARV), in an effort to improve the maneuverability of high performance military aircraft at low-subsonic-speed, high-angle-of-attack conditions. The overall objective of the NASA Lewis effort is to develop inlet analysis technology towards efficient airflow delivery to the engine during these maneuvers. One portion of this inlet analysis technology uses computational fluid dynamics to predict installed inlet performance. Most of the F/A-18A HARV geometry, which includes the ramp/splitter plate, side diverter and slot, inlet lip and upper diverter, and deflected leading-edge flap has been modeled. The empennage and rear fuselage have not. A pair of vortex generators located on the bottom wall of the inlet were not modeled initially. These vortex generators were installed to alleviate any flow separation that may be induced by the wheel well protrusion into the inlet wall. Calculations completed with the PARC3D code showed that the pressure recovery has been underpredicted and the flow distortion over-predicted. To improve the correlation of PARC3D predictions with flight and wind tunnel tests, the vortex generators were included in the grid geometry and the results are presented in this report. The grid totals 27 blocks or 1.3 million grid points for the half model, which includes the vortex generator grid blocks. Two flight cases were calculated, a high speed case with a Mach number of 0.8 and angle of attack of 3.4; and a low speed case with a Mach number of 0.43 and angle of attack of 32.2. The vortex generators have a significant effect on the inlet boundary layers at high speed, low angle of attack; and have no effect at low speed, high angle of attack.
Lober, R.R.; Tautges, T.J.; Vaughan, C.T.
1997-03-01
Paving is an automated mesh generation algorithm which produces all-quadrilateral elements. It can additionally generate these elements in varying sizes such that the resulting mesh adapts to a function distribution, such as an error function. While powerful, conventional paving is a very serial algorithm in its operation. Parallel paving is the extension of serial paving into parallel environments to perform the same meshing functions as conventional paving only on distributed, discretized models. This extension allows large, adaptive, parallel finite element simulations to take advantage of paving`s meshing capabilities for h-remap remeshing. A significantly modified version of the CUBIT mesh generation code has been developed to host the parallel paving algorithm and demonstrate its capabilities on both two dimensional and three dimensional surface geometries and compare the resulting parallel produced meshes to conventionally paved meshes for mesh quality and algorithm performance. Sandia`s {open_quotes}tiling{close_quotes} dynamic load balancing code has also been extended to work with the paving algorithm to retain parallel efficiency as subdomains undergo iterative mesh refinement.
MeshGUI: A Mesh Generation and Editing Toolset for the ADCIRC Model
2008-02-08
40 APPENDIX II: Creating Input Data for Meshcreate…………………….. 42 a. Bathymetric Data: Extraction from NRL-DBDB2 Database...The first data file is a boundary file that describes the geographic limits of the mesh to be created . Often the boundary file represents a coastline...constructed to include overland areas as long as supporting topographic information is available. The boundary file can be created using an auxiliary
General application of rapid 3-D digitizing and tool path generation for complex shapes
Kwok, K.S.; Loucks, C.S.; Driessen, B.J.
1997-09-01
A system for automatic tool path generation was developed at Sandia National Laboratories for finish machining operations. The system consists of a commercially available 5-axis milling machine controlled by Sandia developed software. This system was used to remove overspray on cast turbine blades. A laser-based, structured-light sensor, mounted on a tool holder, is used to collect 3D data points around the surface of the turbine blade. Using the digitized model of the blade, a tool path is generated which will drive a 0.375 inch grinding pin around the tip of the blade. A fuzzified digital filter was developed to properly eliminate false sensor readings caused by burrs, holes and overspray. The digital filter was found to successfully generate the correct tool path for a blade with intentionally scanned holes and defects. The fuzzified filter improved the computation efficiency by a factor of 25. For application to general parts, an adaptive scanning algorithm was developed and presented with simulation and experimental results. A right pyramid and an ellipsoid were scanned successfully with the adaptive algorithm in simulation studies. In actual experiments, a nose cone and a turbine blade were successfully scanned. A complex shaped turbine blade was successfully scanned and finished machined using these algorithms.
Lift and thrust generation by a butterfly-like 3D flapping wing model
NASA Astrophysics Data System (ADS)
Suzuki, Kosuke; Inamuro, Takaji
2013-11-01
The flapping flight of tiny insects such as a butterfly is of fundamental interest not only in biology itself but also in its practical use for the development of micro air vehicles. It is known that a butterfly flaps downward for generating lift force and backward for generating thrust force. In this study, we consider a simple butterfly-like 3D flapping wing model whose body is a thin rod, wings are rigid and rectangular, and wing motion is simplified. We investigate the lift and thrust generation by the butterfly-like flapping wing model by using the immersed boundary-lattice Boltzmann method. Firstly, we compute the lift and thrust forces when the body of the model is fixed for Reynolds numbers in the range of 50 - 1000. In addition, we evaluate the supportable mass for each Reynolds number by using the computed lift force. Secondly, we simulate the free flight where the body can move translationally but cannot rotate. As results, we find that the evaluated supportable mass can be supported even in the free flight, and the wing model with the mass and the Reynolds number of a fruit fly can go upward against the gravity. Finally, we simulate the effect of the rotation of the body. As results, we find that the body has a large pitching motion and consequently gets off-balance.
Generation of the 30 M-Mesh Global Digital Surface Model by Alos Prism
NASA Astrophysics Data System (ADS)
Tadono, T.; Nagai, H.; Ishida, H.; Oda, F.; Naito, S.; Minakawa, K.; Iwamoto, H.
2016-06-01
Topographical information is fundamental to many geo-spatial related information and applications on Earth. Remote sensing satellites have the advantage in such fields because they are capable of global observation and repeatedly. Several satellite-based digital elevation datasets were provided to examine global terrains with medium resolutions e.g. the Shuttle Radar Topography Mission (SRTM), the global digital elevation model by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM). A new global digital surface model (DSM) dataset using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi") has been completed on March 2016 by Japan Aerospace Exploration Agency (JAXA) collaborating with NTT DATA Corp. and Remote Sensing Technology Center, Japan. This project is called "ALOS World 3D" (AW3D), and its dataset consists of the global DSM dataset with 0.15 arcsec. pixel spacing (approx. 5 m mesh) and ortho-rectified PRISM image with 2.5 m resolution. JAXA is also processing the global DSM with 1 arcsec. spacing (approx. 30 m mesh) based on the AW3D DSM dataset, and partially releasing it free of charge, which calls "ALOS World 3D 30 m mesh" (AW3D30). The global AW3D30 dataset will be released on May 2016. This paper describes the processing status, a preliminary validation result of the AW3D30 DSM dataset, and its public release status. As a summary of the preliminary validation of AW3D30 DSM, 4.40 m (RMSE) of the height accuracy of the dataset was confirmed using 5,121 independent check points distributed in the world.
Semi-automatic surface and volume mesh generation for subject-specific biomedical geometries.
Sazonov, Igor; Nithiarasu, Perumal
2012-01-01
An overview of surface and volume mesh generation techniques for creating valid meshes to carry out biomedical flows is provided. The methods presented are designed for robust numerical modelling of biofluid flow through subject-specific geometries. The applications of interest are haemodynamics in blood vessels and air flow in upper human respiratory tract. The methods described are designed to minimize distortion to a given domain boundary. They are also designed to generate a triangular surface mesh first and then volume mesh (tetrahedrons) with high quality surface and volume elements. For blood flow applications, a simple procedure to generate a boundary layer mesh is also described. The methods described here are semi-automatic in nature because of the fact that the geometries are complex, and automation of the procedures may be possible if high quality scans are used.
Unstructured and adaptive mesh generation for high Reynolds number viscous flows
NASA Technical Reports Server (NTRS)
Mavriplis, Dimitri J.
1991-01-01
A method for generating and adaptively refining a highly stretched unstructured mesh suitable for the computation of high-Reynolds-number viscous flows about arbitrary two-dimensional geometries was developed. The method is based on the Delaunay triangulation of a predetermined set of points and employs a local mapping in order to achieve the high stretching rates required in the boundary-layer and wake regions. The initial mesh-point distribution is determined in a geometry-adaptive manner which clusters points in regions of high curvature and sharp corners. Adaptive mesh refinement is achieved by adding new points in regions of large flow gradients, and locally retriangulating; thus, obviating the need for global mesh regeneration. Initial and adapted meshes about complex multi-element airfoil geometries are shown and compressible flow solutions are computed on these meshes.
Towards the Next Generation Upper-Mantle 3D Anelastic Tomography
NASA Astrophysics Data System (ADS)
Karaoglu, H.; Romanowicz, B. A.
2015-12-01
In order to distinguish the thermal and compositional heterogeneities in the mantle, it is crucial to resolve the lateral variations not only in seismic velocities but also in intrinsic attenuation. Indeed, the high sensitivity of intrinsic attenuation to temperature and water content, governed by a form of Arrhenius equation, contrasts with the quasi-linear dependence of velocities on both temperature and major element composition. The major challenge in imaging attenuation lies in separating its effects on seismic waves from the elastic ones. The latter originate from the wave propagation in media with strong lateral elastic gradients causing (de)focusing and scattering. We have previously developed a 3D upper-mantle shear attenuation model based on time domain waveform inversion of long period (T > 60s) fundamental and overtone surface wave data (Gung & Romanowicz, 2004). However, at that time, resolution was limited to very long wavelength structure, because elastic models were still rather smooth, and the effects of focusing could only be estimated approximately, using asymptotic normal mode perturbation theory.With recent progress in constraining global mantle shear velocity from waveform tomography based on the Spectral Element Method (e.g. SEMUCB_WM1, French & Romanowicz, 2014), we are now in a position to develop an improved global 3D model of shear attenuation in the upper mantle. In doing so, we use a similar time domain waveform inversion approach, but (1) start with a higher resolution elastic model with better constraints on lateral elastic gradients and (2) jointly invert, in an iterative fashion, for shear attenuation and elastic parameters. Here, we present the results of synthetic tests that confirm our inversion strategy, as well as preliminary results towards the construction of the next generation upper-mantle anelastic model.
Fast DRR generation for 2D to 3D registration on GPUs.
Tornai, Gábor János; Cserey, György; Pappas, Ion
2012-08-01
The generation of digitally reconstructed radiographs (DRRs) is the most time consuming step on the CPU in intensity based two-dimensional x-ray to three-dimensional (CT or 3D rotational x-ray) medical image registration, which has application in several image guided interventions. This work presents optimized DRR rendering on graphical processor units (GPUs) and compares performance achievable on four commercially available devices. A ray-cast based DRR rendering was implemented for a 512 × 512 × 72 CT volume. The block size parameter was optimized for four different GPUs for a region of interest (ROI) of 400 × 225 pixels with different sampling ratios (1.1%-9.1% and 100%). Performance was statistically evaluated and compared for the four GPUs. The method and the block size dependence were validated on the latest GPU for several parameter settings with a public gold standard dataset (512 × 512 × 825 CT) for registration purposes. Depending on the GPU, the full ROI is rendered in 2.7-5.2 ms. If sampling ratio of 1.1%-9.1% is applied, execution time is in the range of 0.3-7.3 ms. On all GPUs, the mean of the execution time increased linearly with respect to the number of pixels if sampling was used. The presented results outperform other results from the literature. This indicates that automatic 2D to 3D registration, which typically requires a couple of hundred DRR renderings to converge, can be performed quasi on-line, in less than a second or depending on the application and hardware in less than a couple of seconds. Accordingly, a whole new field of applications is opened for image guided interventions, where the registration is continuously performed to match the real-time x-ray.
Fast DRR generation for 2D to 3D registration on GPUs
Tornai, Gabor Janos; Cserey, Gyoergy
2012-08-15
Purpose: The generation of digitally reconstructed radiographs (DRRs) is the most time consuming step on the CPU in intensity based two-dimensional x-ray to three-dimensional (CT or 3D rotational x-ray) medical image registration, which has application in several image guided interventions. This work presents optimized DRR rendering on graphical processor units (GPUs) and compares performance achievable on four commercially available devices. Methods: A ray-cast based DRR rendering was implemented for a 512 Multiplication-Sign 512 Multiplication-Sign 72 CT volume. The block size parameter was optimized for four different GPUs for a region of interest (ROI) of 400 Multiplication-Sign 225 pixels with different sampling ratios (1.1%-9.1% and 100%). Performance was statistically evaluated and compared for the four GPUs. The method and the block size dependence were validated on the latest GPU for several parameter settings with a public gold standard dataset (512 Multiplication-Sign 512 Multiplication-Sign 825 CT) for registration purposes. Results: Depending on the GPU, the full ROI is rendered in 2.7-5.2 ms. If sampling ratio of 1.1%-9.1% is applied, execution time is in the range of 0.3-7.3 ms. On all GPUs, the mean of the execution time increased linearly with respect to the number of pixels if sampling was used. Conclusions: The presented results outperform other results from the literature. This indicates that automatic 2D to 3D registration, which typically requires a couple of hundred DRR renderings to converge, can be performed quasi on-line, in less than a second or depending on the application and hardware in less than a couple of seconds. Accordingly, a whole new field of applications is opened for image guided interventions, where the registration is continuously performed to match the real-time x-ray.
Comparative Analysis of 3d Point Clouds Generated from a Freeware and Terrestrial Laser Scanner
NASA Astrophysics Data System (ADS)
Dayal, K. R.; Raghavendra, S.; Pande, H.; Tiwari, P. S.; Chauhan, I.
2017-07-01
In the recent past, several heritage structures have faced destruction due to both human-made incidents and natural calamities that have caused a great loss to the human race regarding its cultural achievements. In this context, the importance of documenting such structures to create a substantial database cannot be emphasised enough. The Clock Tower of Dehradun, India is one such structure. There is a lack of sufficient information in the digital domain, which justified the need to carry out this study. Thus, an attempt has been made to gauge the possibilities of using open source 3D tools such as VSfM to quickly and easily obtain point clouds of an object and assess its quality. The photographs were collected using consumer grade cameras with reasonable effort to ensure overlap. The sparse reconstruction and dense reconstruction were carried out to generate a 3D point cloud model of the tower. A terrestrial laser scanner (TLS) was also used to obtain a point cloud of the tower. The point clouds obtained from the two methods were analyzed to understand the quality of the information present; TLS acquired point cloud being a benchmark to assess the VSfM point cloud. They were compared to analyze the point density and subjected to a plane-fitting test for sample flat portions on the structure. The plane-fitting test revealed the planarity
of the point clouds. A Gauss distribution fit yielded a standard deviation of 0.002 and 0.01 for TLS and VSfM, respectively. For more insight, comparisons with Agisoft Photoscan results were also made.
Lee, W H; Kim, T-S; Cho, M H; Ahn, Y B; Lee, S Y
2006-12-07
In studying bioelectromagnetic problems, finite element analysis (FEA) offers several advantages over conventional methods such as the boundary element method. It allows truly volumetric analysis and incorporation of material properties such as anisotropic conductivity. For FEA, mesh generation is the first critical requirement and there exist many different approaches. However, conventional approaches offered by commercial packages and various algorithms do not generate content-adaptive meshes (cMeshes), resulting in numerous nodes and elements in modelling the conducting domain, and thereby increasing computational load and demand. In this work, we present efficient content-adaptive mesh generation schemes for complex biological volumes of MR images. The presented methodology is fully automatic and generates FE meshes that are adaptive to the geometrical contents of MR images, allowing optimal representation of conducting domain for FEA. We have also evaluated the effect of cMeshes on FEA in three dimensions by comparing the forward solutions from various cMesh head models to the solutions from the reference FE head model in which fine and equidistant FEs constitute the model. The results show that there is a significant gain in computation time with minor loss in numerical accuracy. We believe that cMeshes should be useful in the FEA of bioelectromagnetic problems.
NASA Astrophysics Data System (ADS)
Lee, W. H.; Kim, T.-S.; Cho, M. H.; Ahn, Y. B.; Lee, S. Y.
2006-12-01
In studying bioelectromagnetic problems, finite element analysis (FEA) offers several advantages over conventional methods such as the boundary element method. It allows truly volumetric analysis and incorporation of material properties such as anisotropic conductivity. For FEA, mesh generation is the first critical requirement and there exist many different approaches. However, conventional approaches offered by commercial packages and various algorithms do not generate content-adaptive meshes (cMeshes), resulting in numerous nodes and elements in modelling the conducting domain, and thereby increasing computational load and demand. In this work, we present efficient content-adaptive mesh generation schemes for complex biological volumes of MR images. The presented methodology is fully automatic and generates FE meshes that are adaptive to the geometrical contents of MR images, allowing optimal representation of conducting domain for FEA. We have also evaluated the effect of cMeshes on FEA in three dimensions by comparing the forward solutions from various cMesh head models to the solutions from the reference FE head model in which fine and equidistant FEs constitute the model. The results show that there is a significant gain in computation time with minor loss in numerical accuracy. We believe that cMeshes should be useful in the FEA of bioelectromagnetic problems.
2D nearly orthogonal mesh generation with controls on distortion functions
USDA-ARS?s Scientific Manuscript database
A method to control the distortion function of the Ryskin and Leal (RL) orthogonal mesh generation system is presented. The proposed method considers the effects from not only the local orthogonal condition but also the local smoothness condition (the geometry and the mesh size) on the distortion fu...
Grid generation and adaptation via Monge-Kantorovich optimization in 2D and 3D
NASA Astrophysics Data System (ADS)
Delzanno, Gian Luca; Chacon, Luis; Finn, John M.
2008-11-01
In a recent paper [1], Monge-Kantorovich (MK) optimization was proposed as a method of grid generation/adaptation in two dimensions (2D). The method is based on the minimization of the L2 norm of grid point displacement, constrained to producing a given positive-definite cell volume distribution (equidistribution constraint). The procedure gives rise to the Monge-Amp'ere (MA) equation: a single, non-linear scalar equation with no free-parameters. The MA equation was solved in Ref. [1] with the Jacobian Free Newton-Krylov technique and several challenging test cases were presented in squared domains in 2D. Here, we extend the work of Ref. [1]. We first formulate the MK approach in physical domains with curved boundary elements and in 3D. We then show the results of applying it to these more general cases. We show that MK optimization produces optimal grids in which the constraint is satisfied numerically to truncation error. [1] G.L. Delzanno, L. Chac'on, J.M. Finn, Y. Chung, G. Lapenta, A new, robust equidistribution method for two-dimensional grid generation, submitted to Journal of Computational Physics (2008).
NASA Astrophysics Data System (ADS)
Shalbaf, Farzaneh; Dokos, Socrates; Lovell, Nigel H.; Turuwhenua, Jason; Vaghefi, Ehsan
2015-12-01
Retinal prosthesis has been proposed to restore vision for those suffering from the retinal pathologies that mainly affect the photoreceptors layer but keep the inner retina intact. Prior to costly risky experimental studies computational modelling of the retina will help to optimize the device parameters and enhance the outcomes. Here, we developed an anatomically detailed computational model of the retina based on OCT data sets. The consecutive OCT images of individual were subsequently segmented to provide a 3D representation of retina in the form of finite elements. Thereafter, the electrical properties of the retina were modelled by implementing partial differential equation on the 3D mesh. Different electrode configurations, that is bipolar and hexapolar configurations, were implemented and the results were compared with the previous computational and experimental studies. Furthermore, the possible effects of the curvature of retinal layers on the current steering through the retina were proposed and linked to the clinical observations.
3D Printing of Conductive Complex Structures with In Situ Generation of Silver Nanoparticles.
Fantino, Erika; Chiappone, Annalisa; Roppolo, Ignazio; Manfredi, Diego; Bongiovanni, Roberta; Pirri, Candido Fabrizio; Calignano, Flaviana
2016-05-01
Coupling the photoreduction of a metal precursor with 3D-printing technology is shown to allow the fabrication of conductive 3D hybrid structures consisting of metal nanoparticles and organic polymers shaped in complex multilayered architectures. 3D conductive structures are fabricated incorporating silver nitrate into a photocurable oligomer in the presence of suitable photoinitiators and exposing them to a digital light system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
NASA Astrophysics Data System (ADS)
Hashimoto, Chihiro; Fukuyama, Eiichi; Matsu'ura, Mitsuhiro
2014-08-01
The generation of interplate earthquakes can be regarded as a process of tectonic stress accumulation and release, driven by relative plate motion. We completed a physics-based simulation system for earthquake generation cycles at plate interfaces in the Japan region, where the Pacific plate is descending beneath the North American and Philippine Sea plates, and the Philippine Sea plate is descending beneath the North American and Eurasian plates. The system is composed of a quasi-static tectonic loading model and a dynamic rupture propagation model, developed on a realistic 3-D plate interface model. The driving force of the system is relative plate motion. In the quasi-static tectonic loading model, mechanical interaction at plate interfaces is rationally represented by the increase of tangential displacement discontinuity (fault slip) across them on the basis of dislocation theory for an elastic surface layer overlying Maxwell-type viscoelastic half-space. In the dynamic rupture propagation model, stress changes due to fault slip motion on non-planar plate interfaces are evaluated with the boundary integral equation method. The progress of seismic (dynamic) or aseismic (quasi-static) fault slip on plate interfaces is governed by a slip- and time-dependent fault constitutive law. As an example, we numerically simulated earthquake generation cycles at the source region of the 1968 Tokachi-oki earthquake on the North American-Pacific plate interface. From the numerical simulation, we can see that postseismic stress relaxation in the asthenosphere accelerates stress accumulation in the source region. When the stress state of the source region is close to a critical level, dynamic rupture is rapidly accelerated and develops over the whole source region. When the stress state is much lower than the critical level, the rupture is not accelerated. This means that the stress state realized by interseismic tectonic loading essentially controls the subsequent dynamic
TOBAGO — a semi-automated approach for the generation of 3-D building models
NASA Astrophysics Data System (ADS)
Gruen, Armin
3-D city models are in increasing demand for a great number of applications. Photogrammetry is a relevant technology that can provide an abundance of geometric, topologic and semantic information concerning these models. The pressure to generate a large amount of data with high degree of accuracy and completeness poses a great challenge to phtogrammetry. The development of automated and semi-automated methods for the generation of those data sets is therefore a key issue in photogrammetric research. We present in this article a strategy and methodology for an efficient generation of even fairly complex building models. Within this concept we request the operator to measure the house roofs from a stereomodel in form of an unstructured point cloud. According to our experience this can be done very quickly. Even a non-experienced operator can measure several hundred roofs or roof units per day. In a second step we fit generic building models fully automatically to these point clouds. The structure information is inherently included in these building models. In such a way geometric, topologic and even semantic data can be handed over to a CAD-system, in our case AutoCad, for further visualization and manipulation. The structuring is achieved in three steps. In a first step a classifier is initiated which recognizes the class of houses a particular roof point cloud belongs to. This recognition step is primarily based on the analysis of the number of ridge points. In the second and third steps the concrete topological relations between roof points are investigated and generic building models are fitted to the point clouds. Based on the technique of constraint-based reasoning two geometrical parsers are solving this problem. We have tested the methodology under a variety of different conditions in several pilot projects. The results will indicate the good performance of our approach. In addition we will demonstrate how the results can be used for visualization (texture
ESCHER: An interactive mesh-generating editor for preparing finite-element input
NASA Technical Reports Server (NTRS)
Oakes, W. R., Jr.
1984-01-01
ESCHER is an interactive mesh generation and editing program designed to help the user create a finite-element mesh, create additional input for finite-element analysis, including initial conditions, boundary conditions, and slidelines, and generate a NEUTRAL FILE that can be postprocessed for input into several finite-element codes, including ADINA, ADINAT, DYNA, NIKE, TSAAS, and ABUQUS. Two important ESCHER capabilities, interactive geometry creation and mesh archival storge are described in detail. Also described is the interactive command language and the use of interactive graphics. The archival storage and restart file is a modular, entity-based mesh data file. Modules of this file correspond to separate editing modes in the mesh editor, with data definition syntax preserved between the interactive commands and the archival storage file. Because ESCHER was expected to be highly interactive, extensive user documentation was provided in the form of an interactive HELP package.
McBride, Cory L. (Elemental Technologies, American Fort, UT); Yarberry, Victor R.; Schmidt, Rodney Cannon; Meyers, Ray J.
2006-11-01
This report describes the SummitView 1.0 computer code developed at Sandia National Laboratories. SummitView is designed to generate a 3D solid model, amenable to visualization and meshing, that represents the end state of a microsystem fabrication process such as the SUMMiT (Sandia Ultra-Planar Multilevel MEMS Technology) V process. Functionally, SummitView performs essentially the same computational task as an earlier code called the 3D Geometry modeler [1]. However, because SummitView is based on 2D instead of 3D data structures and operations, it has significant speed and robustness advantages. As input it requires a definition of both the process itself and the collection of individual 2D masks created by the designer and associated with each of the process steps. The definition of the process is contained in a special process definition file [2] and the 2D masks are contained in MEM format files [3]. The code is written in C++ and consists of a set of classes and routines. The classes represent the geometric data and the SUMMiT V process steps. Classes are provided for the following process steps: Planar Deposition, Planar Etch, Conformal Deposition, Dry Etch, Wet Etch and Release Etch. SummitView is built upon the 2D Boolean library GBL-2D [4], and thus contains all of that library's functionality.
TACO3D. 3-D Finite Element Heat Transfer Code
Mason, W.E.
1992-03-04
TACO3D is a three-dimensional, finite-element program for heat transfer analysis. An extension of the two-dimensional TACO program, it can perform linear and nonlinear analyses and can be used to solve either transient or steady-state problems. The program accepts time-dependent or temperature-dependent material properties, and materials may be isotropic or orthotropic. A variety of time-dependent and temperature-dependent boundary conditions and loadings are available including temperature, flux, convection, and radiation boundary conditions and internal heat generation. Additional specialized features treat enclosure radiation, bulk nodes, and master/slave internal surface conditions (e.g., contact resistance). Data input via a free-field format is provided. A user subprogram feature allows for any type of functional representation of any independent variable. A profile (bandwidth) minimization option is available. The code is limited to implicit time integration for transient solutions. TACO3D has no general mesh generation capability. Rows of evenly-spaced nodes and rows of sequential elements may be generated, but the program relies on separate mesh generators for complex zoning. TACO3D does not have the ability to calculate view factors internally. Graphical representation of data in the form of time history and spatial plots is provided through links to the POSTACO and GRAPE postprocessor codes.
Articular cartilage zonal differentiation via 3D Second-Harmonic Generation imaging microscopy.
Chaudhary, Rajeev; Campbell, Kirby R; Tilbury, Karissa B; Vanderby, Ray; Block, Walter F; Kijowski, Richard; Campagnola, Paul J
2015-04-01
The collagen structure throughout the patella has not been thoroughly investigated by 3D imaging, where the majority of the existing data come from histological cross sections. It is important to have a better understanding of the architecture in normal tissues, where this could then be applied to imaging of diseased states. To address this shortcoming, we investigated the combined use of collagen-specific Second-Harmonic Generation (SHG) imaging and measurement of bulk optical properties to characterize collagen fiber orientations of the histologically defined zones of bovine articular cartilage. Forward and backward SHG intensities of sections from superficial, middle and deep zones were collected as a function of depth and analyzed by Monte Carlo simulations to extract the SHG creation direction, which is related to the fibrillar assembly. Our results revealed differences in SHG forward-backward response between the three zones, where these are consistent with a previously developed model of SHG emission. Some of the findings are consistent with that from other modalities; however, SHG analysis showed the middle zone had the most organized fibril assembly. While not distinct, we also report bulk optical property values for these different zones within the patella. Collectively, these results provide quantitative measurements of structural changes at both the fiber and fibril assembly of the different cartilage zones and reveals structural information not possible by other microscope modalities. This can provide quantitative insight to the collagen fiber network in normal cartilage, which may ultimately be developed as a biomarker for osteoarthritis.
Patchimpattapong, Apisit; Haghighat, Alireza
2001-06-17
The discrete ordinates (S{sub N}) method is widely used to obtain numerical solutions of the transport equation, but there are problems associated with it. To overcome these, an expert system for input preparation is being developed as a tool to reduce users' time and effort. The expert system consists of two parts: an algorithm for generation of an effective mesh distribution for a serial calculation and an algorithm for extension to parallel computing. The first part, discussed in this paper, comprises the following four steps: creation of a geometric model and coarse meshes, calculation of uncollided flux, selection of differencing schemes, and generation of fine-mesh distribution. For the uncollided flux calculation, the code PENFC for calculating uncollided and first-collision fluxes for 3-D Cartesian geometry was developed. The algorithm for calculating the uncollided flux and selecting differencing scheme was tested using the simplified VENUS-3 model. PENFC, which demonstrated good load balancing, yielded good agreement in the uncollided flux calculation compared to PENTRAN.
A 2D-3D strategy for resolving tsunami-generated debris flow in urban environments
NASA Astrophysics Data System (ADS)
Birjukovs Canelas, Ricardo; Conde, Daniel; Garcia-Feal, Orlando; João Telhado, Maria; Ferreira, Rui M. L.
2017-04-01
The incorporation of solids, either sediment from the natural environment or remains from buildings or infrastructures is a relevant feature of tsunami run-up in urban environments, greatly increasing the destructive potential of tsunami propagation. Two-dimensional (2D) models have been used to assess the propagation of the bore, even in dense urban fronts. Computational advances are introduced in this work, namely a fully lagrangian, 3D description of the fluid-solid flow, coupled with a high performance meshless implementation capable of dealing with large domains and fine discretizations. A Smoothed Particle Hydrodynamics (SPH) Navier-Stokes discretization and a Distributed Contact Discrete Element Method (DCDEM) description of solid-solid interactions provide a state-of the-art fluid-solid flow description. Together with support for arbitrary geometries, centimetre scale resolution simulations of a city section in Lisbon downtown are presented. 2D results are used as boundary conditions for the 3D model, characterizing the incoming wave as it approaches the coast. It is shown that the incoming bore is able to mobilize and incorporate standing vehicles and other urban hardware. Such fully featured simulation provides explicit description of the interactions among fluid, floating debris (vehicles and urban furniture), the buildings and the pavement. The proposed model presents both an innovative research tool for the study of these flows and a powerful and robust approach to study, design and test mitigation solutions at the local scale. At the same time, due to the high time and space resolution of these methodologies, new questions are raised: scenario-building and initial configurations play a crucial role but they do not univocally determine the final configuration of the simulation, as the solution of the Navier-Stokes equations for high Reynolds numbers possesses a high number of degrees of freedom. This calls for conducting the simulations in a
NASA Astrophysics Data System (ADS)
Gould, C. A.; Shammas, N. Y. A.; Grainger, S.; Taylor, I.; Simpson, K.
2012-06-01
This paper documents the 3D modeling and simulation of a three couple thermoelectric module using the Synopsys Technology Computer Aided Design (TCAD) semiconductor simulation software. Simulation results are presented for thermoelectric power generation, cooling and heating, and successfully demonstrate the basic thermoelectric principles. The 3D TCAD simulation model of a three couple thermoelectric module can be used in the future to evaluate different thermoelectric materials, device structures, and improve the efficiency and performance of thermoelectric modules.
2015-01-07
AFRL-OSR-VA-TR-2015-0039 High-Fidelity Geometric Modeling and Mesh Generation for Mechanics Characterization of Polycrystalline Materials Yongjie...0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing...From - To) Oct 1, 2011-Sep 30, 2014 4. TITLE AND SUBTITLE High-Fidelity Geometric Modeling and Mesh Generation for Mechanics Characterization of
NASA Astrophysics Data System (ADS)
Colangelo, Antonio C.
2010-05-01
each cell in synthetic slope systems performed by relief unity emulator. The central methodological strategy is to locate the potential rupture surfaces (prs), main material discontinuities, like soil-regolith or regolith-rock transitions. Inner these "prs", we would to outline the effective potential rupture surfaces (eprs). This surface is a sub-set of the "prs" that presents safety factor less than unity (f<1), the sub-region in the "prs" equal or deeper than critical depths. When the effective potential rupture surface acquires significant extension with respect the thickness of critical depth and retaining walls, the "slope stability simulator" generates a synthetic mass movement. The overlay material will slide until that a new equilibrium be attained at residual shear strength. These devices generate graphic 3D cinematic sequences of experiments in synthetic slope systems and numerical results about physical and morphological data about scars and deposits. Thus, we have a detailed geotechnical, morphological, topographic and morphometric description of these mass movements prototypes, for deal with effective mass movements found in the real environments.
3D Printed, Microgroove Pattern-Driven Generation of Oriented Ligamentous Architectures.
Park, Chan Ho; Kim, Kyoung-Hwa; Lee, Yong-Moo; Giannobile, William V; Seol, Yang-Jo
2017-09-08
Specific orientations of regenerated ligaments are crucially required for mechanoresponsive properties and various biomechanical adaptations, which are the key interplay to support mineralized tissues. Although various 2D platforms or 3D printing systems can guide cellular activities or aligned organizations, it remains a challenge to develop ligament-guided, 3D architectures with the angular controllability for parallel, oblique or perpendicular orientations of cells required for biomechanical support of organs. Here, we show the use of scaffold design by additive manufacturing for specific topographies or angulated microgroove patterns to control cell orientations such as parallel (0°), oblique (45°) and perpendicular (90°) angulations. These results demonstrate that ligament cells displayed highly predictable and controllable orientations along microgroove patterns on 3D biopolymeric scaffolds. Our findings demonstrate that 3D printed topographical approaches can regulate spatiotemporal cell organizations that offer strong potential for adaptation to complex tissue defects to regenerate ligament-bone complexes.
Sando, Yusuke; Barada, Daisuke; Yatagai, Toyohiko
2012-09-10
We have derived the basic spectral relation between a 3-D object and its 2-D diffracted wavefront by interpreting the diffraction calculation in the 3-D Fourier domain. Information on the 3-D object, which is inherent in the diffracted wavefront, becomes clear by using this relation. After the derivation, a method for obtaining the Fourier spectrum that is required to synthesize a hologram with a realistic sampling number for visible light is described. Finally, to verify the validity and the practicality of the above-mentioned spectral relation, fast calculation of a series of wavefronts radially diffracted from a 3-D voxel-based object is demonstrated.
Gibelli, Daniele; De Angelis, Danilo; Poppa, Pasquale; Sforza, Chiarella; Cattaneo, Cristina
2017-03-01
Techniques of 2D-3D superimposition are widely used in cases of personal identification from video surveillance systems. However, the progressive improvement of 3D image acquisition technology will enable operators to perform also 3D-3D facial superimposition. This study aims at analyzing the possible applications of 3D-3D superimposition to personal identification, although from a theoretical point of view. Twenty subjects underwent a facial 3D scan by stereophotogrammetry twice at different time periods. Scans were superimposed two by two according to nine landmarks, and root-mean-square (RMS) value of point-to-point distances was calculated. When the two superimposed models belonged to the same individual, RMS value was 2.10 mm, while it was 4.47 mm in mismatches with a statistically significant difference (p < 0.0001). This experiment shows the potential of 3D-3D superimposition: Further studies are needed to ascertain technical limits which may occur in practice and to improve methods useful in the forensic practice. © 2016 American Academy of Forensic Sciences.
Marsano, Anna; Conficconi, Chiara; Lemme, Marta; Occhetta, Paola; Gaudiello, Emanuele; Votta, Emiliano; Cerino, Giulia; Redaelli, Alberto; Rasponi, Marco
2016-02-07
In the past few years, microfluidic-based technology has developed microscale models recapitulating key physical and biological cues typical of the native myocardium. However, the application of controlled physiological uniaxial cyclic strains on a defined three-dimension cellular environment is not yet possible. Two-dimension mechanical stimulation was particularly investigated, neglecting the complex three-dimensional cell-cell and cell-matrix interactions. For this purpose, we developed a heart-on-a-chip platform, which recapitulates the physiologic mechanical environment experienced by cells in the native myocardium. The device includes an array of hanging posts to confine cell-laden gels, and a pneumatic actuation system to induce homogeneous uniaxial cyclic strains to the 3D cell constructs during culture. The device was used to generate mature and highly functional micro-engineered cardiac tissues (μECTs), from both neonatal rat and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), strongly suggesting the robustness of our engineered cardiac micro-niche. Our results demonstrated that the cyclic strain was effectively highly uniaxial and uniformly transferred to cells in culture. As compared to control, stimulated μECTs showed superior cardiac differentiation, as well as electrical and mechanical coupling, owing to a remarkable increase in junction complexes. Mechanical stimulation also promoted early spontaneous synchronous beating and better contractile capability in response to electric pacing. Pacing analyses of hiPSC-CM constructs upon controlled administration of isoprenaline showed further promising applications of our platform in drug discovery, delivery and toxicology fields. The proposed heart-on-a-chip device represents a relevant step forward in the field, providing a standard functional three-dimensional cardiac model to possibly predict signs of hypertrophic changes in cardiac phenotype by mechanical and biochemical co-stimulation.
NASA Astrophysics Data System (ADS)
Griesbaum, Luisa; Marx, Sabrina; Höfle, Bernhard
2017-07-01
In recent years, the number of people affected by flooding caused by extreme weather events has increased considerably. In order to provide support in disaster recovery or to develop mitigation plans, accurate flood information is necessary. Particularly pluvial urban floods, characterized by high temporal and spatial variations, are not well documented. This study proposes a new, low-cost approach to determining local flood elevation and inundation depth of buildings based on user-generated flood images. It first applies close-range digital photogrammetry to generate a geo-referenced 3-D point cloud. Second, based on estimated camera orientation parameters, the flood level captured in a single flood image is mapped to the previously derived point cloud. The local flood elevation and the building inundation depth can then be derived automatically from the point cloud. The proposed method is carried out once for each of 66 different flood images showing the same building façade. An overall accuracy of 0.05 m with an uncertainty of ±0.13 m for the derived flood elevation within the area of interest as well as an accuracy of 0.13 m ± 0.10 m for the determined building inundation depth is achieved. Our results demonstrate that the proposed method can provide reliable flood information on a local scale using user-generated flood images as input. The approach can thus allow inundation depth maps to be derived even in complex urban environments with relatively high accuracies.
Choi, Kyongsik; Kim, Joohwan; Lim, Yongjun; Lee, Byoungho
2005-12-26
A novel full parallax and viewing-angle enhanced computer-generated holographic (CGH) three-dimensional (3D) display system is proposed and implemented by combining an integral lens array and colorized synthetic phase holograms displayed on a phase-type spatial light modulator. For analyzing the viewing-angle limitations of our CGH 3D display system, we provide some theoretical background and introduce a simple ray-tracing method for 3D image reconstruction. From our method we can get continuously varying full parallax 3D images with the viewing angle about +/-6 degrees . To design the colorized phase holograms, we used a modified iterative Fourier transform algorithm and we could obtain a high diffraction efficiency (~92.5%) and a large signal-to-noise ratio (~11dB) from our simulation results. Finally we show some experimental results that verify our concept and demonstrate the full parallax viewing-angle enhanced color CGH display system.
NASA Astrophysics Data System (ADS)
Zhang, Zhao; Liu, Juan; Jia, Jia; Li, Xin; Pan, Yijie; Han, Jian; Hu, Bin; Wang, Yongtian
2013-12-01
The real-time holographic display encounters heavy computational load of computer-generated holograms and precisely intensity modulation of 3D images reconstructed by phase-only holograms. In this study, we demonstrate a method for reducing memory usage and modulating the intensity in 3D holographic display. The proposed method can eliminate the redundant information of holograms by employing the non-uniform sampling technique. By combining with the novel look-up table method, 70% reduction in the storage amount can be reached. The gray-scale modulation of 3D images reconstructed by phase-only holograms can be extended either. We perform both numerical simulations and optical experiments to verify the practicability of this method, and the results match well with each other. It is believed that the proposed method can be used in 3D dynamic holographic display and design of the diffractive phase elements.
Generation of a tumor spheroid in a microgravity environment as a 3D model of melanoma.
Marrero, Bernadette; Messina, Jane L; Heller, Richard
2009-10-01
An in vitro 3D model was developed utilizing a synthetic microgravity environment to facilitate studying the cell interactions. 2D monolayer cell culture models have been successfully used to understand various cellular reactions that occur in vivo. There are some limitations to the 2D model that are apparent when compared to cells grown in a 3D matrix. For example, some proteins that are not expressed in a 2D model are found up-regulated in the 3D matrix. In this paper, we discuss techniques used to develop the first known large, free-floating 3D tissue model used to establish tumor spheroids. The bioreactor system known as the High Aspect Ratio Vessel (HARVs) was used to provide a microgravity environment. The HARVs promoted aggregation of keratinocytes (HaCaT) that formed a construct that served as scaffolding for the growth of mouse melanoma. Although there is an emphasis on building a 3D model with the proper extracellular matrix and stroma, we were able to develop a model that excluded the use of matrigel. Immunohistochemistry and apoptosis assays provided evidence that this 3D model supports B16.F10 cell growth, proliferation, and synthesis of extracellular matrix. Immunofluorescence showed that melanoma cells interact with one another displaying observable cellular morphological changes. The goal of engineering a 3D tissue model is to collect new information about cancer development and develop new potential treatment regimens that can be translated to in vivo models while reducing the use of laboratory animals.
Geospatial Data Processing for 3d City Model Generation, Management and Visualization
NASA Astrophysics Data System (ADS)
Toschi, I.; Nocerino, E.; Remondino, F.; Revolti, A.; Soria, G.; Piffer, S.
2017-05-01
Recent developments of 3D technologies and tools have increased availability and relevance of 3D data (from 3D points to complete city models) in the geospatial and geo-information domains. Nevertheless, the potential of 3D data is still underexploited and mainly confined to visualization purposes. Therefore, the major challenge today is to create automatic procedures that make best use of available technologies and data for the benefits and needs of public administrations (PA) and national mapping agencies (NMA) involved in "smart city" applications. The paper aims to demonstrate a step forward in this process by presenting the results of the SENECA project (Smart and SustaiNablE City from Above - http://seneca.fbk.eu). State-of-the-art processing solutions are investigated in order to (i) efficiently exploit the photogrammetric workflow (aerial triangulation and dense image matching), (ii) derive topologically and geometrically accurate 3D geo-objects (i.e. building models) at various levels of detail and (iii) link geometries with non-spatial information within a 3D geo-database management system accessible via web-based client. The developed methodology is tested on two case studies, i.e. the cities of Trento (Italy) and Graz (Austria). Both spatial (i.e. nadir and oblique imagery) and non-spatial (i.e. cadastral information and building energy consumptions) data are collected and used as input for the project workflow, starting from 3D geometry capture and modelling in urban scenarios to geometry enrichment and management within a dedicated webGIS platform.
Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T. III
2013-04-15
Purpose: The authors previously reported on a three-dimensional computer-generated breast phantom, based on empirical human image data, including a realistic finite-element based compression model that was capable of simulating multimodality imaging data. The computerized breast phantoms are a hybrid of two phantom generation techniques, combining empirical breast CT (bCT) data with flexible computer graphics techniques. However, to date, these phantoms have been based on single human subjects. In this paper, the authors report on a new method to generate multiple phantoms, simulating additional subjects from the limited set of original dedicated breast CT data. The authors developed an image morphing technique to construct new phantoms by gradually transitioning between two human subject datasets, with the potential to generate hundreds of additional pseudoindependent phantoms from the limited bCT cases. The authors conducted a preliminary subjective assessment with a limited number of observers (n= 4) to illustrate how realistic the simulated images generated with the pseudoindependent phantoms appeared. Methods: Several mesh-based geometric transformations were developed to generate distorted breast datasets from the original human subject data. Segmented bCT data from two different human subjects were used as the 'base' and 'target' for morphing. Several combinations of transformations were applied to morph between the 'base' and 'target' datasets such as changing the breast shape, rotating the glandular data, and changing the distribution of the glandular tissue. Following the morphing, regions of skin and fat were assigned to the morphed dataset in order to appropriately assign mechanical properties during the compression simulation. The resulting morphed breast was compressed using a finite element algorithm and simulated mammograms were generated using techniques described previously. Sixty-two simulated mammograms, generated from morphing three human
Li, Yiju; Gao, Tingting; Yang, Zhi; Chen, Chaoji; Luo, Wei; Song, Jianwei; Hitz, Emily; Jia, Chao; Zhou, Yubing; Liu, Boyang; Yang, Bao; Hu, Liangbing
2017-07-01
Using solar energy to generate steam is a clean and sustainable approach to addressing the issue of water shortage. The current challenge for solar steam generation is to develop easy-to-manufacture and scalable methods which can convert solar irradiation into exploitable thermal energy with high efficiency. Although various material and structure designs have been reported, high efficiency in solar steam generation usually can be achieved only at concentrated solar illumination. For the first time, 3D printing to construct an all-in-one evaporator with a concave structure for high-efficiency solar steam generation under 1 sun illumination is used. The solar-steam-generation device has a high porosity (97.3%) and efficient broadband solar absorption (>97%). The 3D-printed porous evaporator with intrinsic low thermal conductivity enables heat localization and effectively alleviates thermal dissipation to the bulk water. As a result, the 3D-printed evaporator has a high solar steam efficiency of 85.6% under 1 sun illumination (1 kW m(-2) ), which is among the best compared with other reported evaporators. The all-in-one structure design using the advanced 3D printing fabrication technique offers a new approach to solar energy harvesting for high-efficiency steam generation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
An anisotropic scale-invariant unstructured mesh generator suitable for volumetric imaging data
Kuprat, Andrew P.; Einstein, Daniel R.
2009-01-01
We present a boundary-fitted, scale-invariant unstructured tetrahedral mesh generation algorithm that enables registration of element size to local feature size. Given an input triangulated surface mesh, a feature size field is determined by casting rays normal to the surface and into the geometry and then performing gradient-limiting operations to enforce continuity of the resulting field. Surface mesh density is adjusted to be proportional to the feature size field and then a layered anisotropic volume mesh is generated. This mesh is “scale-invariant” in that roughly the same number of layers of mesh exist in mesh cross-sections, between a minimum scale size Lmin and a maximum scale size Lmax. We illustrate how this field can be used to produce quality grids for computational fluid dynamics based simulations of challenging, topologically complex biological surfaces derived from magnetic resonance images. The algorithm is implemented in the Pacific Northwest National Laboratory (PNNL) version of the Los Alamos grid toolbox LaGriT[14]. Research funded by the National Heart and Blood Institute Award 1RO1HL073598-01A1. PMID:19784397
FORTRAN program for generating a two-dimensional orthogonal mesh between two arbitrary boundaries
NASA Technical Reports Server (NTRS)
Mcnally, W. D.
1972-01-01
A FORTRAN 4 program is presented which computes and plots coordinates for a two-dimensional orthogonal mesh in the region between the walls of a flow channel. The program is designed for a channel containing a body about which flow passes and which spans the channel from one wall to the other. However, the condition that the channel contain an immersed body can be easily removed from the program. Input to the program consists of spline points of the channel walls and the body geometry. Output includes printed and plotted coordinates of the generated orthogonal mesh and angles of the mesh with the horizontal plane.
2D nearly orthogonal mesh generation with controls on distortion function
NASA Astrophysics Data System (ADS)
Zhang, Yaoxin; Jia, Yafei; Wang, Sam S. Y.
2006-11-01
A method to control the distortion function of the Ryskin and Leal (RL) orthogonal mesh generation system is presented. The proposed method considers the effects from not only the local orthogonal condition but also the local smoothness condition (the geometry and the mesh size) on the distortion function. The distortion function is determined by both the scale factors and the averaged scale factors of the constant mesh lines. Two adjustable parameters are used to control the local balance of the orthogonality and the smoothness. The proposed method is successfully applied to several benchmark examples and the natural river channels with complex geometries.
Lithographically-generated 3D lamella layers and their structural color.
Zhang, Sichao; Chen, Yifang; Lu, Bingrui; Liu, Jianpeng; Shao, Jinhai; Xu, Chen
2016-04-28
Inspired by the structural color from the multilayer nanophotonic structures in Morpho butterfly wing scales, 3D lamellae layers in dielectric polymers (polymethyl methacrylate, PMMA) with n ∼ 1.5 were designed and fabricated by standard top-down electron beam lithography with one-step exposure followed by an alternating development/dissolution process of PMMA/LOR (lift-off resist) multilayers. This work offers direct proof of the structural blue/green color via lithographically-replicated PMMA/air multilayers, analogous to those in real Morpho butterfly wings. The success of nanolithography in this work for the 3D lamellae structures in dielectric polymers not only enables us to gain deeper insight into the mysterious blue color of the Morpho butterfly wings, but also breaks through the bottleneck in technical development toward broad applications in gas/liquid sensors, 3D meta-materials, coloring media, and infrared imaging devices, etc.
Lithographically-generated 3D lamella layers and their structural color
NASA Astrophysics Data System (ADS)
Zhang, Sichao; Chen, Yifang; Lu, Bingrui; Liu, Jianpeng; Shao, Jinhai; Xu, Chen
2016-04-01
Inspired by the structural color from the multilayer nanophotonic structures in Morpho butterfly wing scales, 3D lamellae layers in dielectric polymers (polymethyl methacrylate, PMMA) with n ~ 1.5 were designed and fabricated by standard top-down electron beam lithography with one-step exposure followed by an alternating development/dissolution process of PMMA/LOR (lift-off resist) multilayers. This work offers direct proof of the structural blue/green color via lithographically-replicated PMMA/air multilayers, analogous to those in real Morpho butterfly wings. The success of nanolithography in this work for the 3D lamellae structures in dielectric polymers not only enables us to gain deeper insight into the mysterious blue color of the Morpho butterfly wings, but also breaks through the bottleneck in technical development toward broad applications in gas/liquid sensors, 3D meta-materials, coloring media, and infrared imaging devices, etc.
NASA Astrophysics Data System (ADS)
Samian, R. S.; Abbassi, A.; Ghazanfarian, J.
2013-09-01
The thermal performance of two-dimensional (2D) field-effect transistors (FET) is investigated frequently by solving the Fourier heat diffusion law and the Boltzmann transport equation (BTE). With the introduction of the new generation of 3D FETs in which their thickness is less than the phonon mean-free-path it is necessary to carefully simulate the thermal performance of such devices. This paper numerically integrates the BTE in common 2D transistors including planar single layer and Silicon-On-Insulator (SOI) transistor, and the new generation of 3D transistors including FinFET and Tri-Gate devices. In order to decrease the directional dependency of results in 3D simulations; the Legendre equal-weight (PN-EW) quadrature set has been employed. It is found that if similar switching time is assumed for 3D and 2D FETs while the new generation of 3D FETs has less net energy consumption, they have higher hot-spot temperature. The results show continuous heat flux distribution normal to the silicon/oxide interface while the temperature jump is seen at the interface in double layer transistors.
Generating fractal-like surfaces on general purpose mesh-connected computers
NASA Technical Reports Server (NTRS)
Wainer, Michael
1988-01-01
Realistic images of natural surfaces are often generated using computationally expensive stochastic modeling techniques. Here a parallel procedure to generate such models is presented. The target machines are general-purpose mesh-connected computers. The complexity of the procedure is similar to that of a proposed special-purpose parallel fractal generator.
Improved Second-Generation 3-D Volumetric Display System. Revision 2
1998-10-01
submarines operate in littoral waters, awareness of the ocean bottom has increased. In the case of the Navy’s new 3-D display, sonar data of the ocean...color for group viewing in the Submarine Attack Center to guide the submarine in shallow waters, live and in real time. In the case of the 3-D Volu...considering the following. In the case of volumetric scanning, a typical volume with a resolution of 1000 voxels on each side would contain (1000)3
Human hepatocytes loaded in 3D bioprinting generate mini-liver.
Zhong, Cheng; Xie, Hai-Yang; Zhou, Lin; Xu, Xiao; Zheng, Shu-Sen
2016-10-01
Because of an increasing discrepancy between the number of potential liver graft recipients and the number of organs available, scientists are trying to create artificial liver to mimic normal liver function and therefore, to support the patient's liver when in dysfunction. 3D printing technique meets this purpose. The present study was to test the feasibility of 3D hydrogel scaffolds for liver engineering. We fabricated 3D hydrogel scaffolds with a bioprinter. The biocompatibility of 3D hydrogel scaffolds was tested. Sixty nude mice were randomly divided into four groups, with 15 mice in each group: control, hydrogel, hydrogel with L02 (cell line HL-7702), and hydrogel with hepatocyte growth factor (HGF). Cells were cultured and deposited in scaffolds which were subsequently engrafted into livers after partial hepatectomy and radiation-induced liver damage (RILD). The engrafted tissues were examined after two weeks. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, total bilirubin, CYP1A2, CYP2C9, glutathione S-transferase (a-GST), and UDP-glucuronosyl transferase (UGT-2) were compared among the groups. Hematoxylin-eosin (HE) staining and immunohistochemistry of cKit and cytokeratin 18 (CK18) of engrafted tissues were evaluated. The survival time of the mice was also compared among the four groups. 3D hydrogel scaffolds did not impact the viability of cells. The levels of ALT, AST, albumin, total bilirubin, CYP1A2, CYP2C9, a-GST and UGT-2 were significantly improved in mice engrafted with 3D scaffold loaded with L02 compared with those in control and scaffold only (P<0.05). HE staining showed clear liver tissue and immunohistochemistry of cKit and CK18 were positive in the engrafted tissue. Mice treated with 3D scaffold+L02 cells had longer survival time compared with those in control and scaffold only (P<0.05). 3D scaffold has the potential of recreating liver tissue and partial liver functions and can be used in the
Sparsity-based fast CGH generation using layer-based approach for 3D point cloud model
NASA Astrophysics Data System (ADS)
Kim, Hak Gu; Jeong, Hyunwook; Ro, Yong Man
2017-03-01
Computer generated hologram (CGH) is becoming increasingly important for a 3-D display in various applications including virtual reality. In the CGH, holographic fringe patterns are generated by numerically calculating them on computer simulation systems. However, a heavy computational cost is required to calculate the complex amplitude on CGH plane for all points of 3D objects. This paper proposes a new fast CGH generation based on the sparsity of CGH for 3D point cloud model. The aim of the proposed method is to significantly reduce computational complexity while maintaining the quality of the holographic fringe patterns. To that end, we present a new layer-based approach for calculating the complex amplitude distribution on the CGH plane by using sparse FFT (sFFT). We observe the CGH of a layer of 3D objects is sparse so that dominant CGH is rapidly generated from a small set of signals by sFFT. Experimental results have shown that the proposed method is one order of magnitude faster than recently reported fast CGH generation.
NASA Astrophysics Data System (ADS)
Wibowo, Arief C.; Smith, Mark D.; Yeon, Jeongho; Halasyamani, P. Shiv; zur Loye, Hans-Conrad
2012-11-01
Two new 3D bismuth containing coordination polymers are reported along with their single crystal structures and SHG properties. Compound 1: Bi2O2(pydc) (pydc=pyridine-2, 5-dicarboxylate), crystallizes in the monoclinic, polar space group, P21 (a=9.6479(9) Å, b=4.2349(4) Å, c=11.9615(11) Å, β=109.587(1)°), which contains Bi2O2 chains that are connected into a 3D structure via the pydc ligands. Compound 2: Bi4Na4(1R3S-cam)8(EtOH)3.1(H2O)3.4 (1R3S cam=1R3S-camphoric acid) crystallizes in the monoclinic, polar space group, P21 (a=19.0855(7) Å, b=13.7706(5) Å, c=19.2429(7) Å, β=90.701(1)°) and is a true 3D coordination polymer. These are two example of SHG compounds prepared using unsymmetric ligands (compound 1) or chiral ligands (compound 2), together with metals that often exhibit stereochemically-active lone pairs, such as Bi3+, a synthetic approach that resulted in polar, non-centrosymmetric, 3D metal-organic coordination polymer.
Modeling, mesh generation, and adaptive numerical methods for partial differential equations
Babuska, I.; Henshaw, W.D.; Oliger, J.E.; Flaherty, J.E.; Hopcroft, J.E.; Tezduyar, T.
1995-12-31
Mesh generation is one of the most time consuming aspects of computational solutions of problems involving partial differential equations. It is, furthermore, no longer acceptable to compute solutions without proper verification that specified accuracy criteria are being satisfied. Mesh generation must be related to the solution through computable estimates of discretization errors. Thus, an iterative process of alternate mesh and solution generation evolves in an adaptive manner with the end result that the solution is computed to prescribed specifications in an optimal, or at least efficient, manner. While mesh generation and adaptive strategies are becoming available, major computational challenges remain. One, in particular, involves moving boundaries and interfaces, such as free-surface flows and fluid-structure interactions. A 3-week program was held from July 5 to July 23, 1993 with 173 participants and 66 keynote, invited, and contributed presentations. This volume represents written versions of 21 of these lectures. These proceedings are organized roughly in order of their presentation at the workshop. Thus, the initial papers are concerned with geometry and mesh generation and discuss the representation of physical objects and surfaces on a computer and techniques to use this data to generate, principally, unstructured meshes of tetrahedral or hexahedral elements. The remainder of the papers cover adaptive strategies, error estimation, and applications. Several submissions deal with high-order p- and hp-refinement methods where mesh refinement/coarsening (h-refinement) is combined with local variation of method order (p-refinement). Combinations of mathematically verified and physically motivated approaches to error estimation are represented. Applications center on fluid mechanics. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Han, Dong Ju; Jung, Jae Hwan; Choi, Jong Seob; Kim, Yong Tae; Seo, Tae Seok
2013-10-21
Spherical 3D graphite microballs (3D GMs) and their nanohybrids (3D GM-Fe3O4 nanoparticles) were synthesized by using a microfluidic droplet generator and a thermal evaporation-induced capillary compression method. Using the 3D GM-Fe3O4 nanoparticle as a support for polymerization, 3D GM-polypyrrole composites were produced with a unique core-shell structure.
Wibowo, Arief C.; Smith, Mark D.; Yeon, Jeongho; Halasyamani, P. Shiv; Loye, Hans-Conrad zur
2012-11-15
Two new 3D bismuth containing coordination polymers are reported along with their single crystal structures and SHG properties. Compound 1: Bi{sub 2}O{sub 2}(pydc) (pydc=pyridine-2, 5-dicarboxylate), crystallizes in the monoclinic, polar space group, P2{sub 1} (a=9.6479(9) A, b=4.2349(4) A, c=11.9615(11) A, {beta}=109.587(1) Degree-Sign ), which contains Bi{sub 2}O{sub 2} chains that are connected into a 3D structure via the pydc ligands. Compound 2: Bi{sub 4}Na{sub 4}(1R3S-cam){sub 8}(EtOH){sub 3.1}(H{sub 2}O){sub 3.4} (1R3S cam=1R3S-camphoric acid) crystallizes in the monoclinic, polar space group, P2{sub 1} (a=19.0855(7) A, b=13.7706(5) A, c=19.2429(7) A, {beta}=90.701(1) Degree-Sign ) and is a true 3D coordination polymer. These are two example of SHG compounds prepared using unsymmetric ligands (compound 1) or chiral ligands (compound 2), together with metals that often exhibit stereochemically-active lone pairs, such as Bi{sup 3+}, a synthetic approach that resulted in polar, non-centrosymmetric, 3D metal-organic coordination polymer. - Graphical Abstract: Structures of two new, polar, 3D Bismuth(III)-based coordination polymers: Bi{sub 2}O{sub 2}(pydc) (compound 1), and Bi{sub 4}Na{sub 4}(1R3S-cam){sub 8}(EtOH){sub 3.1}(H{sub 2}O){sub 3.4} (compound 2). Highlights: Black-Right-Pointing-Pointer New, polar, 3D Bismuth(III)-based coordination polymers. Black-Right-Pointing-Pointer First polar bismuth-based coordination polymers synthesized via a 'hybrid' strategy. Black-Right-Pointing-Pointer Combination of stereochemically-active lone pairs and unsymmetrical or chiral ligands. Black-Right-Pointing-Pointer Synthesis of class C-SHG materials based on Kurtz-Perry categories.
Automated and integrated mask generation from a CAD constructed 3D model.
Schiek, Richard Louis; Schmidt, Rodney Cannon
2005-03-01
We have developed and implemented a method which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micromachining. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology to the model. The 3D model is first separated into bodies that are non-intersecting, made from different materials or only linked through a ground plane. Next, for each body unique horizontal cross sections are located and arranged into a tree based on their topological relationship. A branch-wise search of the tree uncovers locations where deposition boundaries must lie and identifies candidate masks creating a generic mask set for the 3D model. Finally, in the last step specific process requirements are considered that may constrain the generic mask set.
Generation of orientation tools for automated zebrafish screening assays using desktop 3D printing
2014-01-01
Background The zebrafish has been established as the main vertebrate model system for whole organism screening applications. However, the lack of consistent positioning of zebrafish embryos within wells of microtiter plates remains an obstacle for the comparative analysis of images acquired in automated screening assays. While technical solutions to the orientation problem exist, dissemination is often hindered by the lack of simple and inexpensive ways of distributing and duplicating tools. Results Here, we provide a cost effective method for the production of 96-well plate compatible zebrafish orientation tools using a desktop 3D printer. The printed tools enable the positioning and orientation of zebrafish embryos within cavities formed in agarose. Their applicability is demonstrated by acquiring lateral and dorsal views of zebrafish embryos arrayed within microtiter plates using an automated screening microscope. This enables the consistent visualization of morphological phenotypes and reporter gene expression patterns. Conclusions The designs are refined versions of previously demonstrated devices with added functionality and strongly reduced production costs. All corresponding 3D models are freely available and digital design can be easily shared electronically. In combination with the increasingly widespread usage of 3D printers, this provides access to the developed tools to a wide range of zebrafish users. Finally, the design files can serve as templates for other additive and subtractive fabrication methods. PMID:24886511
3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation
Yang, Fan; Bhutani, Nidhi
2015-01-01
Human articular cartilage is highly susceptible to damage and has limited self-repair and regeneration potential. Cell-based strategies to engineer cartilage tissue offer a promising solution to repair articular cartilage. To select the optimal cell source for tissue repair, it is important to develop an appropriate culture platform to systematically examine the biological and biomechanical differences in the tissue-engineered cartilage by different cell sources. Here we applied a three-dimensional (3D) biomimetic hydrogel culture platform to systematically examine cartilage regeneration potential of juvenile, adult, and osteoarthritic (OA) chondrocytes. The 3D biomimetic hydrogel consisted of synthetic component poly(ethylene glycol) and bioactive component chondroitin sulfate, which provides a physiologically relevant microenvironment for in vitro culture of chondrocytes. In addition, the scaffold may be potentially used for cell delivery for cartilage repair in vivo. Cartilage tissue engineered in the scaffold can be evaluated using quantitative gene expression, immunofluorescence staining, biochemical assays, and mechanical testing. Utilizing these outcomes, we were able to characterize the differential regenerative potential of chondrocytes of varying age, both at the gene expression level and in the biochemical and biomechanical properties of the engineered cartilage tissue. The 3D culture model could be applied to investigate the molecular and functional differences among chondrocytes and progenitor cells from different stages of normal or aberrant development. PMID:26484414
Unstructured Polyhedral Mesh Thermal Radiation Diffusion
Palmer, T.S.; Zika, M.R.; Madsen, N.K.
2000-07-27
Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.
NASA Astrophysics Data System (ADS)
Zacharek, M.; Delis, P.; Kedzierski, M.; Fryskowska, A.
2017-05-01
These studies have been conductedusing non-metric digital camera and dense image matching algorithms, as non-contact methods of creating monuments documentation.In order toprocess the imagery, few open-source software and algorithms of generating adense point cloud from images have been executed. In the research, the OSM Bundler, VisualSFM software, and web application ARC3D were used. Images obtained for each of the investigated objects were processed using those applications, and then dense point clouds and textured 3D models were created. As a result of post-processing, obtained models were filtered and scaled.The research showedthat even using the open-source software it is possible toobtain accurate 3D models of structures (with an accuracy of a few centimeters), but for the purpose of documentation and conservation of cultural and historical heritage, such accuracy can be insufficient.
NASA Astrophysics Data System (ADS)
Castillo, Carlos; Zarco-Tejada, Pablo; Laredo, Mario; Gómez, Jose Alfonso
2013-04-01
Major advances have been made recently in automatic 3D photo-reconstruction techniques using uncalibrated and non-metric cameras (James and Robson, 2012). However, its application on soil conservation studies and landscape feature identification is currently at the outset. The aim of this work is to compare the performance of a remote sensing technique using a digital camera mounted on an airborne platform, with 3D photo-reconstruction, a method already validated for gully erosion assessment purposes (Castillo et al., 2012). A field survey was conducted in November 2012 in a 250 m-long gully located in field crops on a Vertisol in Cordoba (Spain). The airborne campaign was conducted with a 4000x3000 digital camera installed onboard an aircraft flying at 300 m above ground level to acquire 6 cm resolution imagery. A total of 990 images were acquired over the area ensuring a large overlap in the across- and along-track direction of the aircraft. An ortho-mosaic and the digital surface model (DSM) were obtained through automatic aerial triangulation and camera calibration methods. For the field-level photo-reconstruction technique, the gully was divided in several reaches to allow appropriate reconstruction (about 150 pictures taken per reach) and, finally, the resulting point clouds were merged into a unique mesh. A centimetric-accuracy GPS provided a benchmark dataset for gully perimeter and distinguishable reference points in order to allow the assessment of measurement errors of the airborne technique and the georeferenciation of the photo-reconstruction 3D model. The uncertainty on the gully limits definition was explicitly addressed by comparison of several criteria obtained by 3D models (slope and second derivative) with the outer perimeter obtained by the GPS operator identifying visually the change in slope at the top of the gully walls. In this study we discussed the magnitude of planimetric and altimetric errors and the differences observed between the
Analysis automation with paving: A new quadrilateral meshing technique
Blacker, T.D. ); Stephenson, M.B.; Canann, S. )
1990-01-01
This paper describes the impact of paving, a new automatic mesh generation algorithm, on the analysis portion of the design process. Paving generates an all-quadrilateral mesh in arbitrary 2D geometries. The paving technique significantly impacts the analysis process by drastically reducing the time and expertise requirements of traditional mesh generation. Paving produces a high quality mesh based on geometric boundary definitions and user specified element sizing constraints. In this paper we describe the paving algorithm, discuss varying aspects of the impact of the technique on design automation, and elaborate on current research into 3D all-hexahedral mesh generation. 11 refs., 10 figs.
Detecting Translation Errors in CAD Surfaces and Preparing Geometries for Mesh Generation
Petersson, N Anders; Chand, K K
2001-08-27
The authors have developed tools for the efficient preparation of CAD geometries for mesh generation. Geometries are read from IGES files and then maintained in a boundary-representation consisting of a patchwork of trimmed and untrimmed surfaces. Gross errors in the geometry can be identified and removed automatically while a user interface is provided for manipulating the geometry (such as correcting invalid trimming curves or removing unwanted details). Modifying the geometry by adding or deleting surfaces and/or sectioning it by arbitrary planes (e.g. symmetry planes) is also supported. These tools are used for robust and accurate geometry models for initial mesh generation and will be applied to in situ mesh generation requirements of moving and adaptive grid simulations.
NASA Astrophysics Data System (ADS)
Jansen, Gunnar; Sohrabi, Reza; Miller, Stephen A.
2017-02-01
Short for Hexahedra from Unique Location in (K)convex Polyhedra - HULK is a simple and efficient algorithm to generate hexahedral meshes from generic STL files describing a geological model to be used in simulation tools based on the finite element, finite volume or finite difference methods. Using binary space partitioning of the input geometry and octree refinement on the grid, a successive increase in accuracy of the mesh is achieved. We present the theoretical basis as well as the implementation procedure with three geological models with varying complexity, providing the basis on which the algorithm is evaluated. HULK generates high accuracy discretizations with cell counts suitable for state-of-the-art subsurface simulators and provides a new method for hexahedral mesh generation in geological settings.
Adil, Maroof M.; Rodrigues, Gonçalo M. C.; Kulkarni, Rishikesh U.; Rao, Antara T.; Chernavsky, Nicole E.; Miller, Evan W.; Schaffer, David V.
2017-01-01
Pluripotent stem cells (PSCs) have major potential as an unlimited source of functional cells for many biomedical applications; however, the development of cell manufacturing systems to enable this promise faces many challenges. For example, there have been major recent advances in the generation of midbrain dopaminergic (mDA) neurons from stem cells for Parkinson’s Disease (PD) therapy; however, production of these cells typically involves undefined components and difficult to scale 2D culture formats. Here, we used a fully defined, 3D, thermoresponsive biomaterial platform to rapidly generate large numbers of action-potential firing mDA neurons after 25 days of differentiation (~40% tyrosine hydroxylase (TH) positive, maturing into 25% cells exhibiting mDA neuron-like spiking behavior). Importantly, mDA neurons generated in 3D exhibited a 30-fold increase in viability upon implantation into rat striatum compared to neurons generated on 2D, consistent with the elevated expression of survival markers FOXA2 and EN1 in 3D. A defined, scalable, and resource-efficient cell culture platform can thus rapidly generate high quality differentiated cells, both neurons and potentially other cell types, with strong potential to accelerate both basic and translational research. PMID:28091566
Stokes, Harold T; Campbell, Branton J; van Smaalen, Sander
2011-01-01
A complete table of (3 + 1)D, (3 + 2)D and (3 + 3)D superspace groups (SSGs) has been enumerated that corrects omissions and duplicate entries in previous tables of superspace groups and Bravais classes. The theoretical methods employed are not new, though the implementation is both novel and robust. The paper also describes conventions for assigning a unique one-line symbol for each group in the table. Finally, a new online data repository is introduced that delivers more complete information about each SSG than has been presented previously.
Binzoni, Tiziano; Torricelli, Alessandro; Giust, Remo; Sanguinetti, Bruno; Bernhard, Paul; Spinelli, Lorenzo
2014-01-01
A bone tissue phantom prototype allowing to test, in general, optical flowmeters at large interoptode spacings, such as laser-Doppler flowmetry or diffuse correlation spectroscopy, has been developed by 3D-stereolithography technique. It has been demonstrated that complex tissue vascular systems of any geometrical shape can be conceived. Absorption coefficient, reduced scattering coefficient and refractive index of the optical phantom have been measured to ensure that the optical parameters reasonably reproduce real human bone tissue in vivo. An experimental demonstration of a possible use of the optical phantom, utilizing a laser-Doppler flowmeter, is also presented. PMID:25136496
NASA Astrophysics Data System (ADS)
Zhao, Christine; Solomon, Justin; Sturgeon, Gregory M.; Gehm, Michael E.; Catenacci, Matthew; Wiley, Benjamin J.; Samei, Ehsan; Lo, Joseph Y.
2017-03-01
Physical breast phantoms provide a standard method to test, optimize, and develop clinical mammography systems, including new digital breast tomosynthesis (DBT) systems. In previous work, we produced an anthropomorphic phantom based on 500x500x500 μm breast CT data using commercial 3D printing. We now introduce an improved phantom based on a new cohort of virtual models with 155x155x155 μm voxels and fabricated through voxelized 3D printing and dithering, which confer higher resolution and greater control over contrast. This new generation includes a uniform chest wall extension for evaluating conventional QC metrics. The uniform region contains a grayscale step wedge, chest wall coverage markers, fiducial markers, spheres, and metal ink stickers of line pairs and edges to assess contrast, resolution, artifact spread function, MTF, and other criteria. We also experimented with doping photopolymer material with calcium, iodine, and zinc to increase our current contrast. In particular, zinc was discovered to significantly increase attenuation beyond 100% breast density with a linear relationship between zinc concentration and attenuation or breast density. This linear relationship was retained when the zinc-doped material was applied in conjunction with 3D printing. As we move towards our long term goal of phantoms that are indistinguishable from patients, this new generation of anthropomorphic physical breast phantom validates our voxelized printing process, demonstrates the utility of a uniform QC region with features from 3D printing and metal ink stickers, and shows potential for improved contrast via doping.
Wood, Scott T; Dean, Brian C; Dean, Delphine
2013-04-01
This paper presents a novel computer vision algorithm to analyze 3D stacks of confocal images of fluorescently stained single cells. The goal of the algorithm is to create representative in silico model structures that can be imported into finite element analysis software for mechanical characterization. Segmentation of cell and nucleus boundaries is accomplished via standard thresholding methods. Using novel linear programming methods, a representative actin stress fiber network is generated by computing a linear superposition of fibers having minimum discrepancy compared with an experimental 3D confocal image. Qualitative validation is performed through analysis of seven 3D confocal image stacks of adherent vascular smooth muscle cells (VSMCs) grown in 2D culture. The presented method is able to automatically generate 3D geometries of the cell's boundary, nucleus, and representative F-actin network based on standard cell microscopy data. These geometries can be used for direct importation and implementation in structural finite element models for analysis of the mechanics of a single cell to potentially speed discoveries in the fields of regenerative medicine, mechanobiology, and drug discovery.
Joo, Kyung-Il; Kim, Mugeon; Park, Min-Kyu; Park, Heewon; Kim, Byeonggon; Hahn, JoonKu; Kim, Hak-Rin
2016-01-01
We propose a liquid crystal (LC)-based 3D optical surface profilometer that can utilize multiple fringe patterns to extract an enhanced 3D surface depth profile. To avoid the optical phase ambiguity and enhance the 3D depth extraction, 16 interference patterns were generated by the LC-based dynamic fringe pattern generator (DFPG) using four-step phase shifting and four-step spatial frequency varying schemes. The DFPG had one common slit with an electrically controllable birefringence (ECB) LC mode and four switching slits with a twisted nematic LC mode. The spatial frequency of the projected fringe pattern could be controlled by selecting one of the switching slits. In addition, moving fringe patterns were obtainable by applying voltages to the ECB LC layer, which varied the phase difference between the common and the selected switching slits. Notably, the DFPG switching time required to project 16 fringe patterns was minimized by utilizing the dual-frequency modulation of the driving waveform to switch the LC layers. We calculated the phase modulation of the DFPG and reconstructed the depth profile of 3D objects using a discrete Fourier transform method and geometric optical parameters. PMID:27801812
NASA Astrophysics Data System (ADS)
Sanzana, P.; Jankowfsky, S.; Branger, F.; Braud, I.; Vargas, X.; Hitschfeld, N.; Gironás, J.
2013-08-01
Distributed hydrological models rely on a spatial discretization composed of homogeneous units representing different areas within the catchment. Hydrological Response Units (HRUs) typically form the basis of such a discretization. HRUs are generally obtained by intersecting raster or vector layers of land uses, soil types, geology and sub-catchments. Polylines maps representing ditches and river drainage networks can also be used. However this overlapping may result in a mesh with numerical and topological problems not highly representative of the terrain. Thus, a pre-processing is needed to improve the mesh in order to avoid negative effects on the performance of the hydrological model. This paper proposes computer-assisted mesh generation tools to obtain a more regular and physically meaningful mesh of HRUs suitable for hydrologic modeling. We combined existing tools with newly developed scripts implemented in GRASS GIS. The developed scripts address the following problems: (1) high heterogeneity in Digital Elevation Model derived properties within the HRUs, (2) correction of concave polygons or polygons with holes inside, (3) segmentation of very large polygons, and (4) bad estimations of units' perimeter and distances among them. The improvement process was applied and tested using two small catchments in France. The improvement of the spatial discretization was further assessed by comparing the representation and arrangement of overland flow paths in the original and improved meshes. Overall, a more realistic physical representation was obtained with the improved meshes, which should enhance the computation of surface and sub-surface flows in a hydrologic model.
A procedure for generating quantitative 3-D camera views of tokamak divertors
Edmonds, P.H.; Medley, S.S.
1996-05-01
A procedure is described for precision modeling of the views for imaging diagnostics monitoring tokamak internal components, particularly high heat flux divertor components. These models are required to enable predictions of resolution and viewing angle for the available viewing locations. Because of the oblique views expected for slot divertors, fully 3-D perspective imaging is required. A suite of matched 3-D CAD, graphics and animation applications are used to provide a fast and flexible technique for reproducing these views. An analytic calculation of the resolution and viewing incidence angle is developed to validate the results of the modeling procedures. The calculation is applicable to any viewed surface describable with a coordinate array. The Tokamak Physics Experiment (TPX) diagnostics for infrared viewing are used as an example to demonstrate the implementation of the tools. For the TPX experiment the available locations are severely constrained by access limitations at the end resulting images are marginal in both resolution and viewing incidence angle. Full coverage of the divertor is possible if an array of cameras is installed at 45 degree toroidal intervals. Two poloidal locations are required in order to view both the upper and lower divertors. The procedures described here provide a complete design tool for in-vessel viewing, both for camera location and for identification of viewed surfaces. Additionally these same tools can be used for the interpretation of the actual images obtained by the actual diagnostic.
Carlson, Aaron L.; Bennett, Neal K.; Francis, Nicola L.; Halikere, Apoorva; Clarke, Stephen; Moore, Jennifer C.; Hart, Ronald P.; Paradiso, Kenneth; Wernig, Marius; Kohn, Joachim; Pang, Zhiping P.; Moghe, Prabhas V.
2016-01-01
Cell replacement therapy with human pluripotent stem cell-derived neurons has the potential to ameliorate neurodegenerative dysfunction and central nervous system injuries, but reprogrammed neurons are dissociated and spatially disorganized during transplantation, rendering poor cell survival, functionality and engraftment in vivo. Here, we present the design of three-dimensional (3D) microtopographic scaffolds, using tunable electrospun microfibrous polymeric substrates that promote in situ stem cell neuronal reprogramming, neural network establishment and support neuronal engraftment into the brain. Scaffold-supported, reprogrammed neuronal networks were successfully grafted into organotypic hippocampal brain slices, showing an ∼3.5-fold improvement in neurite outgrowth and increased action potential firing relative to injected isolated cells. Transplantation of scaffold-supported neuronal networks into mouse brain striatum improved survival ∼38-fold at the injection site relative to injected isolated cells, and allowed delivery of multiple neuronal subtypes. Thus, 3D microscale biomaterials represent a promising platform for the transplantation of therapeutic human neurons with broad neuro-regenerative relevance. PMID:26983594
Numerical investigation of the 3D flow field generated by a self-propelling manta ray
NASA Astrophysics Data System (ADS)
Pederzani, Jean-Noel; Haj-Hariri, Hossein
2010-11-01
A mixed Lagrangian-Eulerian approach is used to solve the three dimensional Navier-Stokes equation around a self-propelling manta ray. The motion of the manta ray is prescribed using a kinematic model fitted to actual biological data. The dependence of thrust production mechanism on Strouhal and Reynolds numbers is investigated. The vortex core structures are accurately plotted using the λ2 criteria; and a correlation between wake structures and propulsive performance is established. This insight is critical in understanding the key flow features that a bio-inspired autonomous vehicle should reproduce in order to swim efficiently. The solution method is implemented on a block-structured Cartesian grid using a volume of fluid approach. To enhance the computational efficiency, a parallel adaptive mesh refinement technique is used. The present method is validated for the flow around a sphere. A basic station keeping control problem for a pitching and lagging wing is also analyzed to show the capability of the code to aid in controller design and stability analysis.
Progress in off-plane computer-generated waveguide holography for near-to-eye 3D display
NASA Astrophysics Data System (ADS)
Jolly, Sundeep; Savidis, Nickolaos; Datta, Bianca; Bove, V. Michael; Smalley, Daniel
2016-03-01
Waveguide holography refers to the use of holographic techniques for the control of guided-wave light in integrated optical devices (e.g., off-plane grating couplers and in-plane distributed Bragg gratings for guided-wave optical filtering). Off-plane computer-generated waveguide holography (CGWH) has also been employed in the generation of simple field distributions for image display. We have previously depicted the design and fabrication of a binary-phase CGWH operating in the Raman-Nath regime for the purposes of near-to-eye 3-D display and as a precursor to a dynamic, transparent flat-panel guided-wave holographic video display. In this paper, we describe design algorithms and fabrication techniques for multilevel phase CGWHs for near-to-eye 3-D display.
EISCAT 3D - The Next Generation European Incoherent Scatter Radar System
NASA Astrophysics Data System (ADS)
Turunen, E.
2009-04-01
A major new research European infrastructure will be constructed in Northern Scandinavia, combining several very large phased-array transmitters/receivers with multiple receiver arrays. The new EISCAT 3D radar system has a design goal of ten times higher temporal and spatial resolution than the present radars, a volumetric radar imaging capability in an extended spatial area with simultaneous full-vector drift velocities, avoiding spatial and temporal ambiguities, having continuous operation modes, short baseline interferometry capability for imaging sub-beamwidth scales, real-time data access for applications and extensive data archiving facilities. Some arrays are very large, in the scale of 30 000 individual antenna elements. The receiver arrays will be located at 50-150 km distance from the illuminators, so that the total system will comprise in the order of 100 000 elements. These extremely large scale atmospheric and space environment radar arrays open up unprecedented science and technology application opportunities, well beyond the traditional ground-based ionospheric remote sensing role of the old incoherent scatter radars. EISCAT 3D was accepted on the European Roadmap for Research Infrastructures by the European Strategy Forum on Research Infrastructures in December 2008. The facility will be constructed as a modular concept by year 2015. The current status of the project is approaching the end of the first 4 MEUR design study, conducted during 2005-2009 by EISCAT Scientific Association, University of Tromsø, Luleå University of Technology, Swedish Institute of Space Physics, Rutherford Appleton Laboratory, and supported by EU FP6 funding. EISCAT Scientific Association operates currently three incoherent scatter radars in Northern Scandinavia on behalf of its associate members in Finland, China, Germany, Japan, Norway, Sweden and United Kingdom, as well as currently supporting partners in France and Russia.
Generation of Multi-Lod 3d City Models in Citygml with the Procedural Modelling Engine RANDOM3DCITY
NASA Astrophysics Data System (ADS)
Biljecki, F.; Ledoux, H.; Stoter, J.
2016-09-01
The production and dissemination of semantic 3D city models is rapidly increasing benefiting a growing number of use cases. However, their availability in multiple LODs and in the CityGML format is still problematic in practice. This hinders applications and experiments where multi-LOD datasets are required as input, for instance, to determine the performance of different LODs in a spatial analysis. An alternative approach to obtain 3D city models is to generate them with procedural modelling, which is - as we discuss in this paper - well suited as a method to source multi-LOD datasets useful for a number of applications. However, procedural modelling has not yet been employed for this purpose. Therefore, we have developed RANDOM3DCITY, an experimental procedural modelling engine for generating synthetic datasets of buildings and other urban features. The engine is designed to produce models in CityGML and does so in multiple LODs. Besides the generation of multiple geometric LODs, we implement the realisation of multiple levels of spatiosemantic coherence, geometric reference variants, and indoor representations. As a result of their permutations, each building can be generated in 392 different CityGML representations, an unprecedented number of modelling variants of the same feature. The datasets produced by RANDOM3DCITY are suited for several applications, as we show in this paper with documented uses. The developed engine is available under an open-source licence at Github at 3d/Random3Dcity"target="_blank">http://github.com/tudelft3d/Random3Dcity.
TMSmesh: A Robust Method for Molecular Surface Mesh Generation Using a Trace Technique.
Chen, Minxin; Lu, Benzhuo
2011-01-11
Qualified, stable, and efficient molecular surface meshing appears to be necessitated by recent developments for realistic mathematical modeling and numerical simulation of biomolecules, especially in implicit solvent modeling (e.g., see a review in B. Z. Lu et al. Commun. Comput. Phys. 2008, 3, 973-1009). In this paper, we present a new method: tracing molecular surface for meshing (TMSmesh) the Gaussian surface of biomolecules. The method computes the surface points by solving a nonlinear equation directly, polygonizes by connecting surface points through a trace technique, and finally outputs a triangulated mesh. TMSmesh has a linear complexity with respect to the number of atoms and is shown to be capable of handling molecules consisting of more than one million atoms, which is usually difficult for the existing methods for surface generation used in molecular visualization and geometry analysis. Moreover, the meshes generated by TMSmesh are successfully tested in boundary element solutions of the Poisson-Boltzmann equation, which directly gives rise to a route to simulate electrostatic solvation of large-scale molecular systems. The binary version of TMSmesh and a set of representative PQR benchmark molecules are downloadable at our Web page http://lsec.cc.ac.cn/∼lubz/Meshing.html .
Investigation of three-dimensional mesh generation with precise controls
NASA Astrophysics Data System (ADS)
Eiseman, Peter R.
1989-01-01
In the grant, a number of accomplishments were made in a variety of ways and in a variety of topics. The ways in which this was achieved were in oral communication with others, in the organization of conferences, in the journal publications, in the direction of graduate studies, and in the computer demonstration of theoretical developments. The topics include a study of shock-vortex interaction and a number of studies in grid generation. Those studies covered algebraic and interactive aspects here converged with the establishment of a powerful control point formulation for arbitrary grid generation.
Generation and Comparison of Tls and SFM Based 3d Models of Solid Shapes in Hydromechanic Research
NASA Astrophysics Data System (ADS)
Zhang, R.; Schneider, D.; Strauß, B.
2016-06-01
The aim of a current study at the Institute of Hydraulic Engineering and Technical Hydromechanics at TU Dresden is to develop a new injection method for quick and economic sealing of dikes or dike bodies, based on a new synthetic material. To validate the technique, an artificial part of a sand dike was built in an experimental hall. The synthetic material was injected, which afterwards spreads in the inside of the dike. After the material was fully solidified, the surrounding sand was removed with an excavator. In this paper, two methods, which applied terrestrial laser scanning (TLS) and structure from motion (SfM) respectively, for the acquisition of a 3D point cloud of the remaining shapes are described and compared. Combining with advanced software packages, a triangulated 3D model was generated and subsequently the volume of vertical sections of the shape were calculated. As the calculation of the volume revealed differences between the TLS and the SfM 3D model, a thorough qualitative comparison of the two models will be presented as well as a detailed accuracy assessment. The main influence of the accuracy is caused by generalisation in case of gaps due to occlusions in the 3D point cloud. Therefore, improvements for the data acquisition with TLS and SfM for such kind of objects are suggested in the paper.
Geometry modeling and grid generation using 3D NURBS control volume
NASA Technical Reports Server (NTRS)
Yu, Tzu-Yi; Soni, Bharat K.; Shih, Ming-Hsin
1995-01-01
The algorithms for volume grid generation using NURBS geometric representation are presented. The parameterization algorithm is enhanced to yield a desired physical distribution on the curve, surface and volume. This approach bridges the gap between CAD surface/volume definition and surface/volume grid generation. Computational examples associated with practical configurations have shown the utilization of these algorithms.
Automated Tetrahedral Mesh Generation for CFD Analysis of Aircraft in Conceptual Design
NASA Technical Reports Server (NTRS)
Ordaz, Irian; Li, Wu; Campbell, Richard L.
2014-01-01
The paper introduces an automation process of generating a tetrahedral mesh for computational fluid dynamics (CFD) analysis of aircraft configurations in early conceptual design. The method was developed for CFD-based sonic boom analysis of supersonic configurations, but can be applied to aerodynamic analysis of aircraft configurations in any flight regime.
An improved nearly-orthogonal structured mesh generation system with smoothness control functions
USDA-ARS?s Scientific Manuscript database
This paper presents an improved nearly-orthogonal structured mesh generation system with a set of smoothness control functions, which were derived based on the ratio between the Jacobian of the transformation matrix and the Jacobian of the metric tensor. The proposed smoothness control functions are...
Generating 3D Images of Sub-glacial Landscapes: Three Antarctic Case Studies
NASA Astrophysics Data System (ADS)
King, E. C.
2011-12-01
The formation mechanism of subglacial landforms such as drumlins and mega-scale glacial lineations remains controversial. Factors include the type and properties of subglacial sediments; the availability and pressurization of water; and the thickness and flow speed of the overlying ice. While new survey techniques have allowed increasingly sophisticated quantification of the morphology of palaeo-bedforms, observation of contemporary examples has remained difficult, thus inhibiting the development of viable models of formation. I have undertaken ground-radar surveys of three currently-active Antarctic ice streams (Rutford Ice Stream, Talutis Inlet and Pine Island Glacier) to map the type and distribution of subglacial landforms to provide primary observations to inform this debate. Each survey used a low frequency (2-4 MHz) impulse radar towed behind a snowmobile. Line spacing was 500 m and along-track trace interval was c. 7.5 m. The processing techniques used to turn raw profile data into 3D landscape images will be described. The technique works well for elongate sub-glacial bedforms but has limitations in accurately mapping bedform terminations and complex bedrock outcrop landscapes. Developments underway for the future include using a robot snowmobile for data acquisition and airborne survey with similar geometry.
3D-Hydrogel Based Polymeric Nanoreactors for Silver Nano-Antimicrobial Composites Generation
Soto-Quintero, Albanelly; Romo-Uribe, Ángel; Bermúdez-Morales, Víctor H.; Quijada-Garrido, Isabel
2017-01-01
This study underscores the development of Ag hydrogel nanocomposites, as smart substrates for antibacterial uses, via innovative in situ reactive and reduction pathways. To this end, two different synthetic strategies were used. Firstly thiol-acrylate (PSA) based hydrogels were attained via thiol-ene and radical polymerization of polyethylene glycol (PEG) and polycaprolactone (PCL). As a second approach, polyurethane (PU) based hydrogels were achieved by condensation polymerization from diisocyanates and PCL and PEG diols. In fact, these syntheses rendered active three-dimensional (3D) hydrogel matrices which were used as nanoreactors for in situ reduction of AgNO3 to silver nanoparticles. A redox chemistry of stannous catalyst in PU hydrogel yielded spherical AgNPs formation, even at 4 °C in the absence of external reductant; and an appropriate thiol-functionalized polymeric network promoted spherical AgNPs well dispersed through PSA hydrogel network, after heating up the swollen hydrogel at 103 °C in the presence of citrate-reductant. Optical and swelling behaviors of both series of hydrogel nanocomposites were investigated as key factors involved in their antimicrobial efficacy over time. Lastly, in vitro antibacterial activity of Ag loaded hydrogels exposed to Pseudomona aeruginosa and Escherichia coli strains indicated a noticeable sustained inhibitory effect, especially for Ag–PU hydrogel nanocomposites with bacterial inhibition growth capabilities up to 120 h cultivation. PMID:28763050
3D-Hydrogel Based Polymeric Nanoreactors for Silver Nano-Antimicrobial Composites Generation.
Soto-Quintero, Albanelly; Romo-Uribe, Ángel; Bermúdez-Morales, Víctor H; Quijada-Garrido, Isabel; Guarrotxena, Nekane
2017-08-01
This study underscores the development of Ag hydrogel nanocomposites, as smart substrates for antibacterial uses, via innovative in situ reactive and reduction pathways. To this end, two different synthetic strategies were used. Firstly thiol-acrylate (PSA) based hydrogels were attained via thiol-ene and radical polymerization of polyethylene glycol (PEG) and polycaprolactone (PCL). As a second approach, polyurethane (PU) based hydrogels were achieved by condensation polymerization from diisocyanates and PCL and PEG diols. In fact, these syntheses rendered active three-dimensional (3D) hydrogel matrices which were used as nanoreactors for in situ reduction of AgNO₃ to silver nanoparticles. A redox chemistry of stannous catalyst in PU hydrogel yielded spherical AgNPs formation, even at 4 °C in the absence of external reductant; and an appropriate thiol-functionalized polymeric network promoted spherical AgNPs well dispersed through PSA hydrogel network, after heating up the swollen hydrogel at 103 °C in the presence of citrate-reductant. Optical and swelling behaviors of both series of hydrogel nanocomposites were investigated as key factors involved in their antimicrobial efficacy over time. Lastly, in vitro antibacterial activity of Ag loaded hydrogels exposed to Pseudomona aeruginosa and Escherichia coli strains indicated a noticeable sustained inhibitory effect, especially for Ag-PU hydrogel nanocomposites with bacterial inhibition growth capabilities up to 120 h cultivation.
Preliminary Results from the Application of Automated Adjoint Code Generation to CFL3D
NASA Technical Reports Server (NTRS)
Carle, Alan; Fagan, Mike; Green, Lawrence L.
1998-01-01
This report describes preliminary results obtained using an automated adjoint code generator for Fortran to augment a widely-used computational fluid dynamics flow solver to compute derivatives. These preliminary results with this augmented code suggest that, even in its infancy, the automated adjoint code generator can accurately and efficiently deliver derivatives for use in transonic Euler-based aerodynamic shape optimization problems with hundreds to thousands of independent design variables.
Savkovic, Vuk; Flämig, Franziska; Schneider, Marie; Sülflow, Katharina; Loth, Tina; Lohrenz, Andrea; Hacker, Michael Christian; Schulz-Siegmund, Michaela; Simon, Jan-Christoph
2016-01-01
Melanocytes differentiated from the stem cells of human hair follicle outer root sheath (ORS) have the potential for developing non-invasive treatments for skin disorders out of a minimal sample: of hair root. With a robust procedure for melanocyte cultivation from the ORS of human hair follicle at hand, this study focused on the identification of a suitable biocompatible, biodegradable carrier as the next step toward their clinical implementation. Polycaprolactone (PCL) is a known biocompatible material used for a number of medical devices. In this study, we have populated electrospun PCL fiber meshes with normal human epidermal melanocytes (NHEM) as well as with hair-follicle-derived human melanocytes from the outer root sheath (HUMORS) and tested their functionality in vitro. PCL fiber meshes evidently provided a niche for melanocytes and supported their melanotic properties. The cells were tested for gene expression of PAX3, PMEL, TYR and MITF, as well as for proliferation, expression of melanocyte marker proteins tyrosinase and glycoprotein 100 (gp100), L-DOPA-tautomerase enzymatic activity and melanin content. Reduced mitochondrial activity and PAX-3 gene expression indicated that the three-dimensional PCL scaffold supported differentiation rather than proliferation of melanocytes. The monitored melanotic features of both the NHEM and HUMORS cultivated on PCL scaffolds significantly exceeded those of two-dimensional adherent cultures.
NASA Technical Reports Server (NTRS)
Steinthorsson, E.; Shih, T. I-P.; Roelke, R. J.
1991-01-01
In order to generate good quality systems for complicated three-dimensional spatial domains, the grid-generation method used must be able to exert rather precise controls over grid-point distributions. Several techniques are presented that enhance control of grid-point distribution for a class of algebraic grid-generation methods known as the two-, four-, and six-boundary methods. These techniques include variable stretching functions from bilinear interpolation, interpolating functions based on tension splines, and normalized K-factors. The techniques developed in this study were incorporated into a new version of GRID3D called GRID3D-v2. The usefulness of GRID3D-v2 was demonstrated by using it to generate a three-dimensional grid system in the coolent passage of a radial turbine blade with serpentine channels and pin fins.
Alessandrini, Martino; De Craene, Mathieu; Bernard, Olivier; Giffard-Roisin, Sophie; Allain, Pascal; Weese, Juergen; Saloux, Eric; Delingette, Herve; Sermesant, Maxime; D'hooge, Jan
2015-01-27
Quantification of cardiac deformation and strain with 3D ultrasound takes considerable research efforts. Nevertheless, a widespread use of these techniques in clinical practice is still held back due to the lack of a solid verification process to quantify and compare performance. In this context, the use of fully synthetic sequences has become an established tool for initial in silico evaluation. Nevertheless, the realism of existing simulation techniques is still too limited to represent reliable benchmarking data. Moreover, the fact that different centers typically make use of in-house developed simulation pipelines makes a fair comparison difficult. In this context, this paper introduces a novel pipeline for the generation of synthetic 3D cardiac ultrasound image sequences. State-of-the art solutions in the fields of electromechanical modeling and ultrasound simulation are combined within an original framework that exploits a real ultrasound recording to learn and simulate realistic speckle textures. The simulated images show typical artifacts that make motion tracking in ultrasound challenging. The ground-truth displacement field is available voxelwise and is fully controlled by the electromechanical model. By progressively modifying mechanical and ultrasound parameters, the sensitivity of 3D strain algorithms to pathology and image properties can be evaluated. The proposed pipeline is used to generate an initial library of 8 sequences including healthy and pathological cases, which is made freely accessible to the research community via our project web-page..
Mittag, U.; Kriechbaumer, A.; Rittweger, J.
2017-01-01
The authors propose a new 3D interpolation algorithm for the generation of digital geometric 3D-models of bones from existing image stacks obtained by peripheral Quantitative Computed Tomography (pQCT) or Magnetic Resonance Imaging (MRI). The technique is based on the interpolation of radial gray value profiles of the pQCT cross sections. The method has been validated by using an ex-vivo human tibia and by comparing interpolated pQCT images with images from scans taken at the same position. A diversity index of <0.4 (1 meaning maximal diversity) even for the structurally complex region of the epiphysis, along with the good agreement of mineral-density-weighted cross-sectional moment of inertia (CSMI), demonstrate the high quality of our interpolation approach. Thus the authors demonstrate that this interpolation scheme can substantially improve the generation of 3D models from sparse scan sets, not only with respect to the outer shape but also with respect to the internal gray-value derived material property distribution. PMID:28574415
Prediction of Tsunami Waves and Runup Generated by 3d Granular Landslides
NASA Astrophysics Data System (ADS)
Mohammed, F.; Fritz, H. M.
2008-12-01
Subaerial and submarine landslides can trigger tsunamis with locally high amplitudes and runup, which can cause devastating effects in the near field region. The 50th anniversary of the Lituya Bay 1958 landslide impact generated mega tsunami recalls the largest tsunami runup of 524m in recorded history. In contrast to earthquake generated tsunamis, landslide generated tsunami sources are not confined to active tectonic regions and therefore are of particular importance for the Atlantic Ocean. Landslide generated tsunamis were studied in the three dimensional NEES tsunami wave basin TWB at OSU based on the generalized Froude similarity. A novel pneumatic landslide generator was deployed to control the landslide geometry and kinematics. Granular materials were used to model deformable landslides. Measurement techniques such as particle image velocimetry (PIV), multiple above and underwater video cameras, multiple acoustic transducer arrays (MTA), as well as resistance wave and runup gauges were applied. The wave generation was characterized by an extremely unsteady three phase flow consisting of the slide granulate, water and air entrained into the flow. The underwater cameras and the MTA provide data on the landslide deformation as it impacts the water surface, penetrates the water and finally deposits on the bottom of the basin. The influence of the landslide volume, shape and the impact speed on the generated tsunami wave characteristics were extensively studied. The experimental data provides prediction models for the generated tsunami wave characteristics based on the initial landslide characteristics and the final slide deposits. PIV provided instantaneous surface velocity vector fields, which gave insight into the kinematics of the landslide and wave generation process. At high impact velocities flow separation occurred on the slide shoulder resulting in a hydrodynamic impact crater. The recorded wave profiles yielded information on the wave propagation and
Walsh, Brian K; Betit, Peter; Fink, James B; Pereira, Luis M; Arnold, John
2016-05-01
Ribavirin is an antiviral drug that can be administered by inhalation. Despite advancements in the oral delivery of this medication, there has been a renewed interested in delivering ribavirin via the pulmonary system. Although data are not conclusive that inhaled ribavirin improves outcomes, we set out to determine whether delivery by a newer generation nebulizer, the vibrating mesh micropump, was as effective as the recommended small-particle aerosol generator system. We compared the physicochemical makeup and concentrations of ribavirin before and after nebulization with 0.9% NaCl and sterile water. An Andersen cascade impactor was used to determine particle size distribution and mass median aerodynamic diameter, and an absolute filter was used to measure total aerosol emitted output and inhaled dose during mechanical ventilation and spontaneous breathing. Ribavirin was analyzed and quantified using high-performance liquid chromatography with tandem mass spectrometric detection. Ribavirin was found to be stable in both 0.9% aqueous NaCl and sterile water with an r(2) value of 0.96 and identical coefficients of variation with no difference in drug concentration before and after nebulization with the vibrating mesh micropump. The small-particle aerosol generator produced a smaller mass median aerodynamic diameter (1.84 μm) than the vibrating mesh micropump (3.63 μm, P = .02); however, there was no significant difference in the proportion of drug mass in the 0.7-4.7-μm particle range. Total drug delivery was similar with the small-particle aerosol generator and vibrating mesh micropump in both spontaneously breathing (P = .77) and mechanical ventilation (P = .48) models. The vibrating mesh micropump nebulizer may provide an effective alternative to the small-particle aerosol generator in administration of ribavirin using NaCl or sterile water, both on and off the ventilator. Further clinical studies are needed to compare efficacy. Copyright © 2016 by Daedalus
Chen, H F; Dong, X C; Zen, B S; Gao, K; Yuan, S G; Panaye, A; Doucet, J P; Fan, B T
2003-08-01
An efficient virtual and rational drug design method is presented. It combines virtual bioactive compound generation with 3D-QSAR model and docking. Using this method, it is possible to generate a lot of highly diverse molecules and find virtual active lead compounds. The method was validated by the study of a set of anti-tumor drugs. With the constraints of pharmacophore obtained by DISCO implemented in SYBYL 6.8, 97 virtual bioactive compounds were generated, and their anti-tumor activities were predicted by CoMFA. Eight structures with high activity were selected and screened by the 3D-QSAR model. The most active generated structure was further investigated by modifying its structure in order to increase the activity. A comparative docking study with telomeric receptor was carried out, and the results showed that the generated structures could form more stable complexes with receptor than the reference compound selected from experimental data. This investigation showed that the proposed method was a feasible way for rational drug design with high screening efficiency.
Thin film passivation of laser generated 3D micro patterns in lithium manganese oxide cathodes
NASA Astrophysics Data System (ADS)
Pröll, J.; Kohler, R.; Bruns, M.; Oberst, V.; Weidler, P. G.; Heißler, S.; Kübel, C.; Scherer, T.; Prang, R.; Seifert, H. J.; Pfleging, W.
2013-03-01
The increasing need for long-life lithium-ion batteries requires the further development of electrode materials. Especially on the cathode side new materials or material composites are needed to increase the cycle lifetime. On the one hand, spinel-type lithium manganese oxide is a promising candidate to be used as cathode material due to its non-toxicity, low cost and good thermal stability. On the other hand, the spinel structure suffers from change in the oxidation state of manganese during cycling which is also accompanied by loss of active material into the liquid electrolyte. The general trend is to enhance the active surface area of the cathode in order to increase lithium-ion mobility through the electrode/electrolyte interface, while an enhanced surface area will also promote chemical degradation. In this work, laser microstructuring of lithium manganese oxide thin films was applied in a first step to increase the active surface area. This was done by using 248 nm excimer laser radiation and chromium/quartz mask imaging techniques. In a second step, high power diode laser-annealing operating at a wavelength of 940 nm was used for forming a cubic spinel-like battery phase. This was verified by means of Raman spectroscopy and cyclic voltammetric measurements. In a last step, the laser patterned thin films were coated with indium tin oxide (ITO) layers with a thickness of 10 nm to 50 nm. The influence of the 3D surface topography as well as the ITO thickness on the electrochemical performance was studied by cyclic voltammetry. Post-mortem studies were carried out by using scanning electron microscopy and focused ion beam analysis.
Patel, Mumukshu D; Cha, Eunho; Choudhary, Nitin; Kang, Chiwon; Lee, Wonki; Hwang, Jun Yeon; Choi, Wonbong
2016-12-09
The advent of advanced electrode materials has led to performance enhancement of traditional lithium ion batteries (LIBs). We present novel binder-free MoS2 coated three-dimensional carbon nanotubes (3D CNTs) as an anode in LIBs. Scanning transmission electron microscopy analysis shows that vertically oriented MoS2 nanoflakes are strongly bonded to CNTs, which provide a high surface area and active electrochemical sites, and enhanced ion conductivity at the interface. The electrochemical performance shows a very high areal capacity of ~1.65 mAh cm(-2) with an areal density of ~0.35 mg cm(-2) at 0.5 C rate and coulombic efficiency of ~99% up to 50 cycles. The unique architecture of 3D CNTs-MoS2 is indicative to be a promising anode for next generation Li-ion batteries with high capacity and long cycle life.
NASA Astrophysics Data System (ADS)
Patel, Mumukshu D.; Cha, Eunho; Choudhary, Nitin; Kang, Chiwon; Lee, Wonki; Hwang, Jun Yeon; Choi, Wonbong
2016-12-01
The advent of advanced electrode materials has led to performance enhancement of traditional lithium ion batteries (LIBs). We present novel binder-free MoS2 coated three-dimensional carbon nanotubes (3D CNTs) as an anode in LIBs. Scanning transmission electron microscopy analysis shows that vertically oriented MoS2 nanoflakes are strongly bonded to CNTs, which provide a high surface area and active electrochemical sites, and enhanced ion conductivity at the interface. The electrochemical performance shows a very high areal capacity of ~1.65 mAh cm-2 with an areal density of ~0.35 mg cm-2 at 0.5 C rate and coulombic efficiency of ~99% up to 50 cycles. The unique architecture of 3D CNTs-MoS2 is indicative to be a promising anode for next generation Li-ion batteries with high capacity and long cycle life.
Linden, Katharina; Dewald, Oliver; Gatzweiler, Eva; Seehase, Matthias; Duerr, Georg Daniel; Dörner, Jonas; Kleppe, Stephanie
2016-01-01
Background Pressure-volume loops (PVL) provide vital information regarding ventricular performance and pathophysiology in cardiac disease. Unfortunately, acquisition of PVL by conductance technology is not feasible in neonates and small children due to the available human catheter size and resulting invasiveness. The aim of the study was to validate the accuracy of PVL in small hearts using volume data obtained by real-time three-dimensional echocardiography (3DE) and simultaneously acquired pressure data. Methods In 17 piglets (weight range: 3.6–8.0 kg) left ventricular PVL were generated by 3DE and simultaneous recordings of ventricular pressure using a mini pressure wire (PVL3D). PVL3D were compared to conductance catheter measurements (PVLCond) under various hemodynamic conditions (baseline, alpha-adrenergic stimulation with phenylephrine, beta-adrenoreceptor-blockage using esmolol). In order to validate the accuracy of 3D volumetric data, cardiac magnetic resonance imaging (CMR) was performed in another 8 piglets. Results Correlation between CMR- and 3DE-derived volumes was good (enddiastolic volume: mean bias -0.03ml ±1.34ml). Computation of PVL3D in small hearts was feasible and comparable to results obtained by conductance technology. Bland-Altman analysis showed a low bias between PVL3D and PVLCond. Systolic and diastolic parameters were closely associated (Intraclass-Correlation Coefficient for: systolic myocardial elastance 0.95, arterial elastance 0.93, diastolic relaxation constant tau 0.90, indexed end-diastolic volume 0.98). Hemodynamic changes under different conditions were well detected by both methods (ICC 0.82 to 0.98). Inter- and intra-observer coefficients of variation were below 5% for all parameters. Conclusions PVL3D generated from 3DE combined with mini pressure wire represent a novel, feasible and reliable method to assess different hemodynamic conditions of cardiac function in hearts comparable to neonate and infant size. This
Parallel octree-based hexahedral mesh generation for eulerian to lagrangian conversion.
Staten, Matthew L.; Owen, Steven James
2010-09-01
Computational simulation must often be performed on domains where materials are represented as scalar quantities or volume fractions at cell centers of an octree-based grid. Common examples include bio-medical, geotechnical or shock physics calculations where interface boundaries are represented only as discrete statistical approximations. In this work, we introduce new methods for generating Lagrangian computational meshes from Eulerian-based data. We focus specifically on shock physics problems that are relevant to ASC codes such as CTH and Alegra. New procedures for generating all-hexahedral finite element meshes from volume fraction data are introduced. A new primal-contouring approach is introduced for defining a geometric domain. New methods for refinement, node smoothing, resolving non-manifold conditions and defining geometry are also introduced as well as an extension of the algorithm to handle tetrahedral meshes. We also describe new scalable MPI-based implementations of these procedures. We describe a new software module, Sculptor, which has been developed for use as an embedded component of CTH. We also describe its interface and its use within the mesh generation code, CUBIT. Several examples are shown to illustrate the capabilities of Sculptor.
Methodology for generating a 3D computerized breast phantom from empirical data
Li, Christina M.; Segars, W. Paul; Tourassi, Georgia D.; Boone, John M.; Dobbins, James T.
2009-01-01
The initial process for creating a flexible three-dimensional computer-generated breast phantom based on empirical data is described. Dedicated breast computed-tomography data were processed to suppress noise and scatter artifacts in the reconstructed image set. An automated algorithm was developed to classify the breast into its primary components. A preliminary phantom defined using subdivision surfaces was generated from the segmented data. To demonstrate potential applications of the phantom, simulated mammographic image data were acquired of the phantom using a simplistic compression model and an analytic projection algorithm directly on the surface model. The simulated image was generated using a model for a polyenergetic cone-beam projection of the compressed phantom. The methods used to create the breast phantom generate resulting images that have a high level of tissue structure detail available and appear similar to actual mammograms. Fractal dimension measurements of simulated images of the phantom are comparatively similar to measurements from images of real human subjects. A realistic and geometrically defined breast phantom that can accurately simulate imaging data may have many applications in breast imaging research. PMID:19673211
A new-generation 3D ozone FACE (Free Air Controlled Exposure).
Paoletti, Elena; Materassi, Alessandro; Fasano, Gianni; Hoshika, Yasutomo; Carriero, Giulia; Silaghi, Diana; Badea, Ovidiu
2017-01-01
To artificially simulate the impacts of ground-level ozone (O3) on vegetation, ozone FACE (Free Air Controlled Exposure) systems are increasingly recommended. We describe here a new-generation, three-dimensional ozone FACE, with O3 diffusion through laser-generated micro-holes, pre-mixing of air and O3, O3 generator with integral oxygen generator, continuous (day/night) exposure and full replication. Based on three O3 levels and assumptions on the pre-industrial O3 levels, we describe principles to calculate relative yield/biomass and estimate impacts even at lower-than-ambient O3 levels. The case study is called FO3X, and is at present the only ozone FACE in Mediterranean climate and one of the very few ozone FACEs investigating more than one stressor at a time. The results presented here will give further impulse to the research on O3 impacts on vegetation all over the world. Copyright © 2016 Elsevier B.V. All rights reserved.
q-plate for the Generation of Terahertz Cylindrical Vector Beams Fabricated by 3D Printing
NASA Astrophysics Data System (ADS)
Hernandez-Serrano, A. I.; Castro-Camus, E.; Lopez-Mago, D.
2017-08-01
We present the design, fabrication, and characterization of a q-plate with continuous birefringence variation at terahertz frequencies. This q-plate was fabricated by three-dimensional printing and is a simple solution for the generation of cylindrical vector beams. This device can find a number of applications in future terahertz technologies such as telecommunications.
A density-controlled triangular and quadrilateral element mesh automatic generation system
NASA Astrophysics Data System (ADS)
Sun, L.; Yeh, G.; Lin, F.; Zhao, G.
2013-12-01
We made an intensive study to develop an automatic mesh generation system based on the theory of Voronoi diagram and front advancing. The objective of this system is to create meshes for numerical modeling of practical engineering problems in the fields of geomechanics, hydrology, hydraulics, and water resources. The input data of the system is a set of given points to form the boundary contour of the analyzed geometry, containing the coordinates, the connections and the point spacing specified by users. Boundary points are generated by recursively inserting midpoints according to the spacing of the input points. For the curved boundaries, B-splines are constructed to interpolate midpoints. For the geometries with concave features and long thin domains, boundary loss problem may occur after generating the Voronoi diagram of boundary points. This problem is resolved by recursively inserting pseudo-points at the midpoints of the missing edges until all the original boundary edges are fully described. In order to ensure the curvature accuracy of curved boundaries, pseudo-points should be eliminated again by corresponding modes. Two criteria for selecting removal modes are employed, the Jacobian and minimum angle. Two methods are used to generate interior points. One is direct method and the other is pre-test method. A comparison of the two methods is also made. Laplacian method is used to smooth the interior points of triangles. For the geometries with several sub-domains, it is required to ensure the conformity of the elements and points on the intersecting boundaries between adjacent sub-domains. We establish corresponding methods to treat the overlapped boundary edges and implement the reasonable distribution and excellent conformity of the triangles and points on the overlapped boundaries. On the basis of the triangular mesh created by Delaunay triangulation, a front-advancing method is used to further generate quadrilateral mesh by combining two connected
Zhang, Wenlu; Feng, Daming; Li, Rongjian; Chernikov, Andrey; Chrisochoides, Nikos; Osgood, Christopher; Konikoff, Charlotte; Newfeld, Stuart; Kumar, Sudhir; Ji, Shuiwang
2013-12-28
Multicellular organisms consist of cells of many different types that are established during development. Each type of cell is characterized by the unique combination of expressed gene products as a result of spatiotemporal gene regulation. Currently, a fundamental challenge in regulatory biology is to elucidate the gene expression controls that generate the complex body plans during development. Recent advances in high-throughput biotechnologies have generated spatiotemporal expression patterns for thousands of genes in the model organism fruit fly Drosophila melanogaster. Existing qualitative methods enhanced by a quantitative analysis based on computational tools we present in this paper would provide promising ways for addressing key scientific questions. We develop a set of computational methods and open source tools for identifying co-expressed embryonic domains and the associated genes simultaneously. To map the expression patterns of many genes into the same coordinate space and account for the embryonic shape variations, we develop a mesh generation method to deform a meshed generic ellipse to each individual embryo. We then develop a co-clustering formulation to cluster the genes and the mesh elements, thereby identifying co-expressed embryonic domains and the associated genes simultaneously. Experimental results indicate that the gene and mesh co-clusters can be correlated to key developmental events during the stages of embryogenesis we study. The open source software tool has been made available at http://compbio.cs.odu.edu/fly/. Our mesh generation and machine learning methods and tools improve upon the flexibility, ease-of-use and accuracy of existing methods.
Ye, Hongqiang; Ma, Qijun; Hou, Yuezhong; Li, Man; Zhou, Yongsheng
2017-04-25
Digital techniques are not clinically applied for 1-piece maxillary prostheses containing an obturator and removable partial denture retained by the remaining teeth because of the difficulty in obtaining sufficiently accurate 3-dimensional (3D) images. The purpose of this pilot clinical study was to generate 3D digital casts of maxillary defects, including the defective region and the maxillary dentition, based on multisource data registration and to evaluate their effectiveness. Twelve participants with maxillary defects were selected. The maxillofacial region was scanned with spiral computer tomography (CT), and the maxillary arch and palate were scanned using an intraoral optical scanner. The 3D images from the CT and intraoral scanner were registered and merged to form a 3D digital cast of the maxillary defect containing the anatomic structures needed for the maxillary prosthesis. This included the defect cavity, maxillary dentition, and palate. Traditional silicone impressions were also made, and stone casts were poured. The accuracy of the digital cast in comparison with that of the stone cast was evaluated by measuring the distance between 4 anatomic landmarks. Differences and consistencies were assessed using paired Student t tests and the intraclass correlation coefficient (ICC). In 3 participants, physical resin casts were produced by rapid prototyping from digital casts. Based on the resin casts, maxillary prostheses were fabricated by using conventional methods and then evaluated in the participants to assess the clinical applicability of the digital casts. Digital casts of the maxillary defects were generated and contained all the anatomic details needed for the maxillary prosthesis. Comparing the digital and stone casts, a paired Student t test indicated that differences in the linear distances between landmarks were not statistically significant (P>.05). High ICC values (0.977 to 0.998) for the interlandmark distances further indicated the high
NASA Technical Reports Server (NTRS)
Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.
2006-01-01
Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.
NASA Technical Reports Server (NTRS)
Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.
2006-01-01
Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.
Magneto Hydrodynamic Simulations of a Magnetic Flux Compression Generator Using ALE3D
2017-07-13
of seed-current for a fast high current when large capacitor banks are not available. A magnetic flux device consists of coils surrounding a...and measured inductance evolution ....... 9 Fig. 7 Generator total magnetic strength for 70-, 117-, and 220-kA s eed-currents...114.30 mm. The initial inductance was approximately 2955 nH, and the final inductance was approximately 160 nH. The stator consisted of a helical coil
Summary on several key techniques in 3D geological modeling.
Mei, Gang
2014-01-01
Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized.
Summary on Several Key Techniques in 3D Geological Modeling
2014-01-01
Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized. PMID:24772029
Shape reconstruction from medical images and quality mesh generation via implicit surfaces
NASA Astrophysics Data System (ADS)
Peiró, J.; Formaggia, L.; Gazzola, M.; Radaelli, A.; Rigamonti, V.
2007-03-01
The ability of automatically reconstructing physiological shapes, of generating computational meshes, and of calculating flow solutions from medical images is enabling the introduction of computational fluid dynamics (CFD) techniques as an additional tool to aid clinical practice.This article presents a set of procedures for the shape reconstruction and triangulation of geometries derived from a set of medical images representing planar cross sections of the object. The reconstruction of the shape of the boundary is based on the interpolation of an implicit function through a set of points obtained from the segmentation of the images. This approach is favoured for its ability of smoothly interpolating between sections of different topology. The boundary of the object is an iso-surface of the implicit function that is approximated by a triangulation extracted by the method of marching cubes. The quality of this triangulation is often neither suitable for mesh generation nor for flow solution. We discuss the use of mesh enhancement techniques to maximize the quality of the triangulation together with curvature adaption to optimize mesh resolution.The proposed methodology is applied to the reconstruction and discretization of two physiological geometries: a femoral by-pass graft and a nasal cavity.
The 3D Recognition, Generation, Fusion, Update and Refinement (RG4) Concept
NASA Technical Reports Server (NTRS)
Maluf, David A.; Cheeseman, Peter; Smelyanskyi, Vadim N.; Kuehnel, Frank; Morris, Robin D.; Norvig, Peter (Technical Monitor)
2001-01-01
This paper describes an active (real time) recognition strategy whereby information is inferred iteratively across several viewpoints in descent imagery. We will show how we use inverse theory within the context of parametric model generation, namely height and spectral reflection functions, to generate model assertions. Using this strategy in an active context implies that, from every viewpoint, the proposed system must refine its hypotheses taking into account the image and the effect of uncertainties as well. The proposed system employs probabilistic solutions to the problem of iteratively merging information (images) from several viewpoints. This involves feeding the posterior distribution from all previous images as a prior for the next view. Novel approaches will be developed to accelerate the inversion search using novel statistic implementations and reducing the model complexity using foveated vision. Foveated vision refers to imagery where the resolution varies across the image. In this paper, we allow the model to be foveated where the highest resolution region is called the foveation region. Typically, the images will have dynamic control of the location of the foveation region. For descent imagery in the Entry, Descent, and Landing (EDL) process, it is possible to have more than one foveation region. This research initiative is directed towards descent imagery in connection with NASA's EDL applications. Three-Dimensional Model Recognition, Generation, Fusion, Update, and Refinement (RGFUR or RG4) for height and the spectral reflection characteristics are in focus for various reasons, one of which is the prospect that their interpretation will provide for real time active vision for automated EDL.
Generation of programmable 3D optical vortex structures through devil's vortex-lens arrays.
Calabuig, Alejandro; Sánchez-Ruiz, Sergio; Martínez-León, Lluís; Tajahuerce, Enrique; Fernández-Alonso, Mercedes; Furlan, Walter D; Monsoriu, Juan A; Pons-Martí, Amparo
2013-08-10
Different spatial distributions of optical vortices have been generated and characterized by implementing arrays of devil's vortex lenses in a reconfigurable spatial light modulator. A simple design procedure assigns the preferred position and topological charge value to each vortex in the structure, tuning the desired angular momentum. Distributions with charges and momenta of the opposite sign have been experimentally demonstrated. The angular velocity exhibited by the phase distribution around the focal plane has been visualized, showing an excellent agreement with the simulations. The practical limits of the method, with interest for applications involving particle transfer and manipulation, have been evaluated.
Computer-generated 3D ultrasound images of the carotid artery
NASA Technical Reports Server (NTRS)
Selzer, Robert H.; Lee, Paul L.; Lai, June Y.; Frieden, Howard J.; Blankenhorn, David H.
1989-01-01
A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.
Computer-generated 3D ultrasound images of the carotid artery
NASA Astrophysics Data System (ADS)
Selzer, Robert H.; Lee, Paul L.; Lai, June Y.; Frieden, Howard J.; Blankenhorn, David H.
A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.
Rigas, Fotis; Sklavounos, Spyros
2005-05-20
Accidental blast wave generation and propagation in the surroundings poses severe threats for people and property. The prediction of overpressure maxima and its change with time at specified distances can lead to useful conclusions in quantitative risk analysis applications. In this paper, the use of a computational fluid dynamics (CFD) code CFX-5.6 on dense explosive detonation events is described. The work deals with the three-dimensional simulation of overpressure wave propagation generated by the detonation of a dense explosive within a small-scale branched tunnel. It also aids at validating the code against published experimental data as well as to study the way that the resulting shock wave propagates in a confined space configuration. Predicted overpressure histories were plotted and compared versus experimental measurements showing a reasonably good agreement. Overpressure maxima and corresponding times were found close to the measured ones confirming that CFDs may constitute a useful tool in explosion hazard assessment procedures. Moreover, it was found that blast wave propagates preserving supersonic speed along the tunnel accompanied by high overpressure levels, and indicating that space confinement favors the formation and maintenance of a shock rather than a weak pressure wave.
Validation of "AW3D" Global Dsm Generated from Alos Prism
NASA Astrophysics Data System (ADS)
Takaku, Junichi; Tadono, Takeo; Tsutsui, Ken; Ichikawa, Mayumi
2016-06-01
Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), one of onboard sensors carried by Advanced Land Observing Satellite (ALOS), was designed to generate worldwide topographic data with its optical stereoscopic observation. It has an exclusive ability to perform a triplet stereo observation which views forward, nadir, and backward along the satellite track in 2.5 m ground resolution, and collected its derived images all over the world during the mission life of the satellite from 2006 through 2011. A new project, which generates global elevation datasets with the image archives, was started in 2014. The data is processed in unprecedented 5 m grid spacing utilizing the original triplet stereo images in 2.5 m resolution. As the number of processed data is growing steadily so that the global land areas are almost covered, a trend of global data qualities became apparent. This paper reports on up-to-date results of the validations for the accuracy of data products as well as the status of data coverage in global areas. The accuracies and error characteristics of datasets are analyzed by the comparison with existing global datasets such as Ice, Cloud, and land Elevation Satellite (ICESat) data, as well as ground control points (GCPs) and the reference Digital Elevation Model (DEM) derived from the airborne Light Detection and Ranging (LiDAR).
Evaluating the Potential of Rtk-Uav for Automatic Point Cloud Generation in 3d Rapid Mapping
NASA Astrophysics Data System (ADS)
Fazeli, H.; Samadzadegan, F.; Dadrasjavan, F.
2016-06-01
During disaster and emergency situations, 3D geospatial data can provide essential information for decision support systems. The utilization of geospatial data using digital surface models as a basic reference is mandatory to provide accurate quick emergency response in so called rapid mapping activities. The recipe between accuracy requirements and time restriction is considered critical in this situations. UAVs as alternative platforms for 3D point cloud acquisition offer potentials because of their flexibility and practicability combined with low cost implementations. Moreover, the high resolution data collected from UAV platforms have the capabilities to provide a quick overview of the disaster area. The target of this paper is to experiment and to evaluate a low-cost system for generation of point clouds using imagery collected from a low altitude small autonomous UAV equipped with customized single frequency RTK module. The customized multi-rotor platform is used in this study. Moreover, electronic hardware is used to simplify user interaction with the UAV as RTK-GPS/Camera synchronization, and beside the synchronization, lever arm calibration is done. The platform is equipped with a Sony NEX-5N, 16.1-megapixel camera as imaging sensor. The lens attached to camera is ZEISS optics, prime lens with F1.8 maximum aperture and 24 mm focal length to deliver outstanding images. All necessary calibrations are performed and flight is implemented over the area of interest at flight height of 120 m above the ground level resulted in 2.38 cm GSD. Earlier to image acquisition, 12 signalized GCPs and 20 check points were distributed in the study area and measured with dualfrequency GPS via RTK technique with horizontal accuracy of σ = 1.5 cm and vertical accuracy of σ = 2.3 cm. results of direct georeferencing are compared to these points and experimental results show that decimeter accuracy level for 3D points cloud with proposed system is achievable, that is suitable
NASA Astrophysics Data System (ADS)
Abraham, Thomas; Scott, Alex; Carthy, Jon; McManus, Bruce
2011-03-01
The structural remodeling of collagen is important in several biological processes such as wound healing, tendon repair, fibrosis and developmental morphogenesis. Multiphoton microscopy, which uses ultra-short femto-second laser pulses as an excitation source, is efficient in the multiphoton excitation fluorescence (MPEF) of exogenous fluorescent labels tagged to various cellular macromolecular objects, as well as in the induction of a highly specific second harmonic generation (SHG) signal from non-centrosymmetric macromolecules such as fibrillar collagens. Although the non-descanned detectors in the reflection geometry have normally been employed for capturing the backward scattered SHG as well as the MPEF signals, considering the wide range of engineered thick tissue imaging applications, there are still un-answered questions about the generated 3D collagen structures because of the directional pattern of SHG signals. The present study dealt with an in vitro collagen-fibroblast raft model in which the stimulation of fibroblast cells induced the lateral orientation of collagen molecules. The SHG signals originating from the 3D collagen matrix were captured simultaneously in both forward and backward scattering directions to understand the collagen structural differences and to generate a comprehensive understanding of collagen matrix remodeling.
NASA Astrophysics Data System (ADS)
Madden, Christopher S.; Richards, Noel J.; Culpepper, Joanne B.
2016-10-01
This paper investigates the ability to develop synthetic scenes in an image generation tool, E-on Vue, and a gaming engine, Unity 3D, which can be used to generate synthetic imagery of target objects across a variety of conditions in land environments. Developments within these tools and gaming engines have allowed the computer gaming industry to dramatically enhance the realism of the games they develop; however they utilise short cuts to ensure that the games run smoothly in real-time to create an immersive effect. Whilst these short cuts may have an impact upon the realism of the synthetic imagery, they do promise a much more time efficient method of developing imagery of different environmental conditions and to investigate the dynamic aspect of military operations that is currently not evaluated in signature analysis. The results presented investigate how some of the common image metrics used in target acquisition modelling, namely the Δμ1, Δμ2, Δμ3, RSS, and Doyle metrics, perform on the synthetic scenes generated by E-on Vue and Unity 3D compared to real imagery of similar scenes. An exploration of the time required to develop the various aspects of the scene to enhance its realism are included, along with an overview of the difficulties associated with trying to recreate specific locations as a virtual scene. This work is an important start towards utilising virtual worlds for visible signature evaluation, and evaluating how equivalent synthetic imagery is to real photographs.
Tsunami Generation and Propagation by 3D deformable Landslides and Application to Scenarios
NASA Astrophysics Data System (ADS)
McFall, Brian C.; Fritz, Hermann M.
2014-05-01
Tsunamis generated by landslides and volcano flank collapse account for some of the most catastrophic natural disasters recorded and can be particularly devastative in the near field region due to locally high wave amplitudes and runup. The events of 1958 Lituya Bay, 1963 Vajont reservoir, 1980 Spirit Lake, 2002 Stromboli and 2010 Haiti demonstrate the danger of tsunamis generated by landslides or volcano flank collapses. Unfortunately critical field data from these events is lacking. Source and runup scenarios based on real world events are physically modeled using generalized Froude similarity in the three dimensional NEES tsunami wave basin at Oregon State University. A novel pneumatic landslide tsunami generator (LTG) was deployed to simulate landslides with varying geometry and kinematics. The bathymetric and topographic scenarios tested with the LTG are the basin-wide propagation and runup, fjord, curved headland fjord and a conical island setting representing a landslide off an island or a volcano flank collapse. The LTG consists of a sliding box filled with 1,350 kg of landslide material which is accelerated by means of four pneumatic pistons down a 2H:1V slope. The landslide is launched from the sliding box and continues to accelerate by gravitational forces up to velocities of 5 m/s. The landslide Froude number at impact with the water is in the range 1
Measuring nonlinear stresses generated by defects in 3D colloidal crystals
NASA Astrophysics Data System (ADS)
Lin, Neil Y. C.; Bierbaum, Matthew; Schall, Peter; Sethna, James P.; Cohen, Itai
2016-11-01
The mechanical, structural and functional properties of crystals are determined by their defects, and the distribution of stresses surrounding these defects has broad implications for the understanding of transport phenomena. When the defect density rises to levels routinely found in real-world materials, transport is governed by local stresses that are predominantly nonlinear. Such stress fields however, cannot be measured using conventional bulk and local measurement techniques. Here, we report direct and spatially resolved experimental measurements of the nonlinear stresses surrounding colloidal crystalline defect cores, and show that the stresses at vacancy cores generate attractive interactions between them. We also directly visualize the softening of crystalline regions surrounding dislocation cores, and find that stress fluctuations in quiescent polycrystals are uniformly distributed rather than localized at grain boundaries, as is the case in strained atomic polycrystals. Nonlinear stress measurements have important implications for strain hardening, yield and fatigue.
Tsunamis generated by 3D granular landslides in various scenarios from fjords to conical islands
NASA Astrophysics Data System (ADS)
McFall, Brian C.; Fritz, Hermann M.
2015-04-01
Landslide generated tsunamis such as in Lituya Bay, Alaska 1958 account for some of the highest recorded tsunami runup heights. Source and runup scenarios based on real world events are physically modeled using generalized Froude similarity in the three dimensional NEES tsunami wave basin at Oregon State University. A novel pneumatic landslide tsunami generator (LTG) was deployed to simulate landslides with varying geometry and kinematics. The bathymetric and topographic scenarios tested with the LTG are the basin-wide propagation and runup, fjord, curved headland fjord and a conical island setting representing a landslide off an island or a volcano flank collapse. The LTG consists of a sliding box filled with 1,350 kg of landslide material which is accelerated by pneumatic pistons down slope. Two different landslide materials are used to study the granulometry effects: naturally rounded river gravel and cobble mixtures. Water surface elevations are recorded by an array of resistance wave gauges. The landslide deformation is measured from above and underwater camera recordings. The landslide deposit is measured on the basin floor with a multiple transducer acoustic array (MTA). Landslide surface reconstruction and kinematics are determined with a stereo particle image velocimetry (PIV) system. Wave runup is recorded with resistance wave gauges along the slope and verified with video image processing. The measured landslide and wave parameters are compared between the planar hill slope used in various scenarios and the convex hill slope of the conical island. The energy conversion rates from the landslide motion to the wave train is quantified for the planar and convex hill slopes. The wave runup data on the opposing headland is analyzed and evaluated with wave theories. The measured landslide and tsunami data serve to validate and advance three-dimensional numerical landslide tsunami prediction models.
Second generation airborne 3D imaging lidars based on photon counting
NASA Astrophysics Data System (ADS)
Degnan, John J.; Wells, David; Machan, Roman; Leventhal, Edward
2007-09-01
The first successful photon-counting airborne laser altimeter was demonstrated in 2001 under NASA's Instrument Incubator Program (IIP). This "micro-altimeter" flew at altitudes up to 22,000 ft (6.7 km) and, using single photon returns in daylight, successfully recorded high resolution images of the underlying topography including soil, low-lying vegetation, tree canopies, water surfaces, man-made structures, ocean waves, and moving vehicles. The lidar, which operated at a wavelength of 532 nm near the peak of the solar irradiance curve, was also able to see the underlying terrain through trees and thick atmospheric haze and performed shallow water bathymetry to depths of a few meters over the Atlantic Ocean and Assawoman Bay off the Virginia coast. Sigma Space Corporation has recently developed second generation systems suitable f