A New Approach to Fully Automatic Mesh Generation
闵卫东; 张征明; 等
1995-01-01
Automatic mesh generation is one of the most important parts in CIMS (Computer Integrated Manufacturing System).A method based on mesh grading propagation which automatically produces a triangular mesh in a multiply connected planar region is presented in this paper.The method decomposes the planar region into convex subregions,using algorithms which run in linear time.For every subregion,an algorithm is used to generate shrinking polygons according to boundary gradings and form delaunay triangulation between two adjacent shrinking polygons,both in linear time.It automatically propagates boundary gradings into the interior of the region and produces satisfactory quasi-uniform mesh.
Procedure for the automatic mesh generation of innovative gear teeth
Radicella Andrea Chiaramonte
2016-01-01
Full Text Available After having described gear wheels with teeth having the two sides constituted by different involutes and their importance in engineering applications, we stress the need for an efficient procedure for the automatic mesh generation of innovative gear teeth. First, we describe the procedure for the subdivision of the tooth profile in the various possible cases, then we show the method for creating the subdivision mesh, defined by two series of curves called meridians and parallels. Finally, we describe how the above procedure for automatic mesh generation is able to solve specific cases that may arise when dealing with teeth having the two sides constituted by different involutes.
Automatic Mesh Generation on a Regular Background Grid
LO S.H; 刘剑飞
2002-01-01
This paper presents an automatic mesh generation procedure on a 2D domainbased on a regular background grid. The idea is to devise a robust mesh generation schemewith equal emphasis on quality and efficiency. Instead of using a traditional regular rectangulargrid, a mesh of equilateral triangles is employed to ensure triangular element of the best qualitywill be preserved in the interior of the domain.As for the boundary, it is to be generated by a node/segment insertion process. Nodes areinserted into the background mesh one by one following the sequence of the domain boundary.The local structure of the mesh is modified based on the Delaunay criterion with the introduc-tion of each node. Those boundary segments, which are not produced in the phase of nodeinsertion, will be recovered through a systematic element swap process. Two theorems will bepresented and proved to set up the theoretical basic of the boundary recovery part. Exampleswill be presented to demonstrate the robustness and the quality of the mesh generated by theproposed technique.
Shape design sensitivities using fully automatic 3-D mesh generation
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.
The mesh-matching algorithm: an automatic 3D mesh generator for Finite element structures
Couteau, B; Lavallee, S; Payan, Yohan; Lavallee, St\\'{e}phane
2000-01-01
Several authors have employed Finite Element Analysis (FEA) for stress and strain analysis in orthopaedic biomechanics. Unfortunately, the use of three-dimensional models is time consuming and consequently the number of analysis to be performed is limited. The authors have investigated a new method allowing automatically 3D mesh generation for structures as complex as bone for example. This method called Mesh-Matching (M-M) algorithm generated automatically customized 3D meshes of bones from an already existing model. The M-M algorithm has been used to generate FE models of ten proximal human femora from an initial one which had been experimentally validated. The new meshes seemed to demonstrate satisfying results.
Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images
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.
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. PMID:26577253
Applications of automatic mesh generation and adaptive methods in computational medicine
Schmidt, J.A.; Macleod, R.S. [Univ. of Utah, Salt Lake City, UT (United States); Johnson, C.R.; Eason, J.C. [Duke Univ., Durham, NC (United States)
1995-12-31
Important problems in Computational Medicine exist that can benefit from the implementation of adaptive mesh refinement techniques. Biological systems are so inherently complex that only efficient models running on state of the art hardware can begin to simulate reality. To tackle the complex geometries associated with medical applications we present a general purpose mesh generation scheme based upon the Delaunay tessellation algorithm and an iterative point generator. In addition, automatic, two- and three-dimensional adaptive mesh refinement methods are presented that are derived from local and global estimates of the finite element error. Mesh generation and adaptive refinement techniques are utilized to obtain accurate approximations of bioelectric fields within anatomically correct models of the heart and human thorax. Specifically, we explore the simulation of cardiac defibrillation and the general forward and inverse problems in electrocardiography (ECG). Comparisons between uniform and adaptive refinement techniques are made to highlight the computational efficiency and accuracy of adaptive methods in the solution of field problems in computational medicine.
Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long
2014-11-01
The authors have developed a method to automatically generate non-uniform CFD mesh for image-based human airway models. The sizes of generated tetrahedral elements vary in both radial and longitudinal directions to account for boundary layer and multiscale nature of pulmonary airflow. The proposed method takes advantage of our previously developed centerline-based geometry reconstruction method. In order to generate the mesh branch by branch in parallel, we used the open-source programs Gmsh and TetGen for surface and volume meshes, respectively. Both programs can specify element sizes by means of background mesh. The size of an arbitrary element in the domain is a function of wall distance, element size on the wall, and element size at the center of airway lumen. The element sizes on the wall are computed based on local flow rate and airway diameter. The total number of elements in the non-uniform mesh (10 M) was about half of that in the uniform mesh, although the computational time for the non-uniform mesh was about twice longer (170 min). The proposed method generates CFD meshes with fine elements near the wall and smooth variation of element size in longitudinal direction, which are required, e.g., for simulations with high flow rate. NIH Grants R01-HL094315, U01-HL114494, and S10-RR022421. Computer time provided by XSEDE.
An expert system for generating an effective mesh distribution for the SN particle transport simulation has been developed. 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. For the first part, the algorithm prepares an effective mesh distribution considering problem physics and the spatial differencing scheme. For the second part, the algorithm determines a parallel-performance-index (PPI), which is defined as the ratio of the granularity to the degree-of-coupling. The parallel-performance-index provides expected performance of an 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. (authors)
Spherical geodesic mesh generation
Fung, Jimmy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kenamond, Mark Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burton, Donald E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shashkov, Mikhail Jurievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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.
Motta, R.S.; Afonso, S.M.B.; Willmersdorf, R.B.; Lyra, P.R.M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Cabral, H.L.D. [TRANSPETRO, Rio de Janeiro, RJ (Brazil); Andrade, E.Q. [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)
2009-07-01
Although the Finite Element Method (FEM) has proved to be a powerful tool to predict the failure pressure of corroded pipes, the generation of good computational models of pipes with corrosion defects can take several days. This makes the use of computational simulation procedure difficult to apply in practice. The main purpose of this work is to develop a set of computational tools to produce automatically models of pipes with defects, ready to be analyzed with commercial FEM programs, starting from a few parameters that locate and provide the main dimensions of the defect or a series of defects. Here these defects can be internal and external and also assume general spatial locations along the pipe. Idealized rectangular and elliptic geometries can be generated. These tools were based on MSC.PATRAN pre and post-processing programs and were written with PCL (Patran Command Language). The program for the automatic generation of models (PIPEFLAW) has a simplified and customized graphical interface, so that an engineer with basic notions of computational simulation with the FEM can generate rapidly models that result in precise and reliable simulations. Some examples of models of pipes with defects generated by the PIPEFLAW system are shown, and the results of numerical analyses, done with the tools presented in this work, are compared with, empiric results. (author)
Milašinović Danko Z.
2008-01-01
Full Text Available Cardiovascular diseases are common and a special difficulty in their curing is diagnostics. Modern medical instruments can provide data that is much more adequate for computer modeling. Computer simulations of blood flow through the cardiovascular organs give powerful advantages to scientists today. The motivation for this work is raw data that our Center recently received from the University Clinical center in Heidelberg from a multislice CT scanner. In this work raw data from CT scanner was used for creating a 3D model of the aorta. In this process we used Gmsh, TetGen (Hang Si as well as our own software tools, and the result was the 8-node (brick mesh on which the calculation was run. The results obtained were very satisfactory so...
Scandalously Parallelizable Mesh Generation
Bortz, David
2011-01-01
We propose a novel approach which employs random sampling to generate an accurate non-uniform mesh for numerically solving Partial Differential Equation Boundary Value Problems (PDE-BVP's). From a uniform probability distribution U over a 1D domain, we sample M discretizations of size N where M>>N. The statistical moments of the solutions to a given BVP on each of the M ultra-sparse meshes provide insight into identifying highly accurate non-uniform meshes. Essentially, we use the pointwise mean and variance of the coarse-grid solutions to construct a mapping Q(x) from uniformly to non-uniformly spaced mesh-points. The error convergence properties of the approximate solution to the PDE-BVP on the non-uniform mesh are superior to a uniform mesh for a certain class of BVP's. In particular, the method works well for BVP's with locally non-smooth solutions. We present a framework for studying the sampled sparse-mesh solutions and provide numerical evidence for the utility of this approach as applied to a set of e...
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.
Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long
2013-11-01
The authors propose a method to automatically generate three-dimensional subject-specific airway geometries and meshes for computational fluid dynamics (CFD) studies of aerosol delivery in the human lungs. The proposed method automatically expands computed tomography (CT)-based airway skeleton to generate the centerline (CL)-based model, and then fits it to the CT-segmented geometry to generate the hybrid CL-CT-based model. To produce a turbulent laryngeal jet known to affect aerosol transport, we developed a physiologically-consistent laryngeal model that can be attached to the trachea of the above models. We used Gmsh to automatically generate the mesh for the above models. To assess the quality of the models, we compared the regional aerosol distributions in a human lung predicted by the hybrid model and the manually generated CT-based model. The aerosol distribution predicted by the hybrid model was consistent with the prediction by the CT-based model. We applied the hybrid model to 8 healthy and 16 severe asthmatic subjects, and average geometric error was 3.8% of the branch radius. The proposed method can be potentially applied to the branch-by-branch analyses of a large population of healthy and diseased lungs. NIH Grants R01-HL-094315 and S10-RR-022421, CT data provided by SARP, and computer time provided by XSEDE.
Automated quadrilateral mesh generation for digital image structures
无
2011-01-01
With the development of advanced imaging technology, digital images are widely used. This paper proposes an automatic quadrilateral mesh generation algorithm for multi-colour imaged structures. It takes an original arbitrary digital image as an input for automatic quadrilateral mesh generation, this includes removing the noise, extracting and smoothing the boundary geometries between different colours, and automatic all-quad mesh generation with the above boundaries as constraints. An application example is...
Problem-adapted mesh generation with FEM-features
Werner, Horst; Weber, Christian; Schilke, Martin
2000-01-01
Today automatic meshing of CAD geometry is the most common method of FEM mesh generation. However, to get results of acceptable accuracy with universal meshing algorithms it is necessary to use rather small-sized elements which leads to high memory and CPU time consumption. Furthermore, the irregularity of automatically generatated meshes makes it difficult to create well-defined local areas with different material properties. A solution for this problem is the application of predefined build...
Cardiovascular and lung mesh generation based on centerlines.
Marchandise, E; Geuzaine, C; Remacle, J F
2013-06-01
We present a fully automatic procedure for the mesh generation of tubular geometries such as blood vessels or airways. The procedure is implemented in the open-source Gmsh software and relies on a centerline description of the input geometry. The presented method can generate different type of meshes: isotropic tetrahedral meshes, anisotropic tetrahedral meshes, and mixed hexahedral/tetrahedral meshes. Additionally, a multiple layered arterial wall can be generated with a variable thickness. All the generated meshes rely on a mesh size field and a mesh metric that is based on centerline descriptions, namely the distance to the centerlines and a local reference system based on the tangent and the normal directions to the centerlines. Different examples show that the proposed method is very efficient and robust and leads to high quality computational meshes. PMID:23606344
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.
GENERATION OF IRREGULAR HEXAGONAL MESHES
Vlasov Aleksandr Nikolaevich
2012-07-01
Decomposition is performed in a constructive way and, as option, it involves meshless representation. Further, this mapping method is used to generate the calculation mesh. In this paper, the authors analyze different cases of mapping onto simply connected and bi-connected canonical domains. They represent forward and backward mapping techniques. Their potential application for generation of nonuniform meshes within the framework of the asymptotic homogenization theory is also performed to assess and project effective characteristics of heterogeneous materials (composites.
Documentation for MeshKit - Reactor Geometry (&mesh) Generator
Jain, Rajeev [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay [Argonne National Lab. (ANL), Argonne, IL (United States)
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.
Pescarini, M.; Orsi, R.; Martinelli, T. [ENEA, Ente per le Nuove Tecnologie, l' Energia e l' Ambiente, Centro Ricerche Ezio Clementel Bologna (Italy)
2003-07-01
In many practical radiation transport applications today the cost for solving refined, large size and complex multi-dimensional problems is not so much computing but is linked to the cumbersome effort required by an expert to prepare a detailed geometrical model, verify and validate that it is correct and represents, to a specified tolerance, the real design or facility. This situation is, in particular, relevant and frequent in reactor core criticality and shielding calculations, with three-dimensional (3D) general purpose radiation transport codes, requiring a very large number of meshes and high performance computers. The need for developing tools that make easier the task to the physicist or engineer, by reducing the time required, by facilitating through effective graphical display the verification of correctness and, finally, that help the interpretation of the results obtained, has clearly emerged. The paper shows the results of efforts in this field through detailed simulations of a complex shielding benchmark experiment. In the context of the activities proposed by the OECD/NEA Nuclear Science Committee (NSC) Task Force on Computing Radiation Dose and Modelling of Radiation-Induced Degradation of Reactor Components (TFRDD), the ENEA-Bologna Nuclear Data Centre contributed with an analysis of the VENUS-3 low-flux neutron shielding benchmark experiment (SCK/CEN-Mol, Belgium). One of the targets of the work was to test the BOT3P system, originally developed at the Nuclear Data Centre in ENEA-Bologna and actually released to OECD/NEA Data Bank for free distribution. BOT3P, ancillary system of the DORT (2D) and TORT (3D) SN codes, permits a flexible automatic generation of spatial mesh grids in Cartesian or cylindrical geometry, through combinatorial geometry algorithms, following a simplified user-friendly approach. This system demonstrated its validity also in core criticality analyses, as for example the Lewis MOX fuel benchmark, permitting to easily
In many practical radiation transport applications today the cost for solving refined, large size and complex multi-dimensional problems is not so much computing but is linked to the cumbersome effort required by an expert to prepare a detailed geometrical model, verify and validate that it is correct and represents, to a specified tolerance, the real design or facility. This situation is, in particular, relevant and frequent in reactor core criticality and shielding calculations, with three-dimensional (3D) general purpose radiation transport codes, requiring a very large number of meshes and high performance computers. The need for developing tools that make easier the task to the physicist or engineer, by reducing the time required, by facilitating through effective graphical display the verification of correctness and, finally, that help the interpretation of the results obtained, has clearly emerged. The paper shows the results of efforts in this field through detailed simulations of a complex shielding benchmark experiment. In the context of the activities proposed by the OECD/NEA Nuclear Science Committee (NSC) Task Force on Computing Radiation Dose and Modelling of Radiation-Induced Degradation of Reactor Components (TFRDD), the ENEA-Bologna Nuclear Data Centre contributed with an analysis of the VENUS-3 low-flux neutron shielding benchmark experiment (SCK/CEN-Mol, Belgium). One of the targets of the work was to test the BOT3P system, originally developed at the Nuclear Data Centre in ENEA-Bologna and actually released to OECD/NEA Data Bank for free distribution. BOT3P, ancillary system of the DORT (2D) and TORT (3D) SN codes, permits a flexible automatic generation of spatial mesh grids in Cartesian or cylindrical geometry, through combinatorial geometry algorithms, following a simplified user-friendly approach. This system demonstrated its validity also in core criticality analyses, as for example the Lewis MOX fuel benchmark, permitting to easily
Gaussian curvature analysis allows for automatic block placement in multi-block hexahedral meshing.
Ramme, Austin J; Shivanna, Kiran H; Magnotta, Vincent A; Grosland, Nicole M
2011-10-01
Musculoskeletal finite element analysis (FEA) has been essential to research in orthopaedic biomechanics. The generation of a volumetric mesh is often the most challenging step in a FEA. Hexahedral meshing tools that are based on a multi-block approach rely on the manual placement of building blocks for their mesh generation scheme. We hypothesise that Gaussian curvature analysis could be used to automatically develop a building block structure for multi-block hexahedral mesh generation. The Automated Building Block Algorithm incorporates principles from differential geometry, combinatorics, statistical analysis and computer science to automatically generate a building block structure to represent a given surface without prior information. We have applied this algorithm to 29 bones of varying geometries and successfully generated a usable mesh in all cases. This work represents a significant advancement in automating the definition of building blocks. PMID:20924860
Volume Decomposition and Feature Recognition for Hexahedral Mesh Generation
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
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.
Automatic Dance Lesson Generation
Yang, Yang; Leung, H.; Yue, Lihua; Deng, LiQun
2012-01-01
In this paper, an automatic lesson generation system is presented which is suitable in a learning-by-mimicking scenario where the learning objects can be represented as multiattribute time series data. The dance is used as an example in this paper to illustrate the idea. Given a dance motion sequence as the input, the proposed lesson generation…
Dancette, S.; Browet, A.; Martin, G.; Willemet, M.; Delannay, L.
2016-06-01
A new procedure for microstructure-based finite element modeling of polycrystalline aggregates is presented. The proposed method relies (i) on an efficient graph-based community detection algorithm for crystallographic data segmentation and feature contour extraction and (ii) on the generation of selectively refined meshes conforming to grain boundaries. It constitutes a versatile and close to automatic environment for meshing complex microstructures. The procedure is illustrated with polycrystal microstructures characterized by orientation imaging microscopy. Hot deformation of a Duplex stainless steel is investigated based on ex-situ EBSD measurements performed on the same region of interest before and after deformation. A finite element mesh representing the initial microstructure is generated and then used in a crystal plasticity simulation of the plane strain compression. Simulation results and experiments are in relatively good agreement, confirming a large potential for such directly coupled experimental and modeling analyses, which is facilitated by the present image-based meshing procedure.
Adaptive mesh generation for image registration and segmentation
Fogtmann, Mads; Larsen, Rasmus
This paper deals with the problem of generating quality tetrahedral meshes for image registration. From an initial coarse mesh the approach matches the mesh to the image volume by combining red-green subdivision and mesh evolution through mesh-to-image matching regularized with a mesh quality...
Three-dimensional modeling and highly refined mesh generation of the aorta artery and its tunics
This paper describes strategies and techniques to perform modeling and automatic mesh generation of the aorta artery and its tunics (adventitia, media and intima walls), using open source codes. The models were constructed in the Blender package and Python scripts were used to export the data necessary for the mesh generation in TetGen. The strategies proposed are able to provide meshes of complicated and irregular volumes, with a large number of mesh elements involved (12,000,000 tetrahedrons approximately). These meshes can be used to perform computational simulations by Finite Element Method (FEM).
Mesh Generation and Adaption for High Reynolds Number RANS Computations Project
National Aeronautics and Space Administration — This proposal offers to provide NASA with an automatic mesh generator for the simulation of aerodynamic flows using Reynolds-Averages Navier-Stokes (RANS) models....
Mesh Generation and Adaption for High Reynolds Number RANS Computations Project
National Aeronautics and Space Administration — The innovation of our Phase II STTR program is to develop and provide to NASA automatic mesh generation software for the simulation of fluid flows using...
Generating quality tetrahedral meshes from binary volumes
Hansen, Mads Fogtmann; Bærentzen, Jakob Andreas; Larsen, Rasmus
2010-01-01
use these measures to generate high quality meshes from signed distance maps. This paper also describes an approach for computing (smooth) signed distance maps from binary volumes as volumetric data in many cases originate from segmentation of objects from imaging techniques such as CT, MRI, etc. The...
Automatic Tooth Segmentation of Dental Mesh Based on Harmonic Fields.
Liao, Sheng-hui; Liu, Shi-jian; Zou, Bei-ji; Ding, Xi; Liang, Ye; Huang, Jun-hui
2015-01-01
An important preprocess in computer-aided orthodontics is to segment teeth from the dental models accurately, which should involve manual interactions as few as possible. But fully automatic partition of all teeth is not a trivial task, since teeth occur in different shapes and their arrangements vary substantially from one individual to another. The difficulty is exacerbated when severe teeth malocclusion and crowding problems occur, which is a common occurrence in clinical cases. Most published methods in this area either are inaccurate or require lots of manual interactions. Motivated by the state-of-the-art general mesh segmentation methods that adopted the theory of harmonic field to detect partition boundaries, this paper proposes a novel, dental-targeted segmentation framework for dental meshes. With a specially designed weighting scheme and a strategy of a priori knowledge to guide the assignment of harmonic constraints, this method can identify teeth partition boundaries effectively. Extensive experiments and quantitative analysis demonstrate that the proposed method is able to partition high-quality teeth automatically with robustness and efficiency. PMID:26413507
Automatic Tooth Segmentation of Dental Mesh Based on Harmonic Fields
Sheng-hui Liao
2015-01-01
Full Text Available An important preprocess in computer-aided orthodontics is to segment teeth from the dental models accurately, which should involve manual interactions as few as possible. But fully automatic partition of all teeth is not a trivial task, since teeth occur in different shapes and their arrangements vary substantially from one individual to another. The difficulty is exacerbated when severe teeth malocclusion and crowding problems occur, which is a common occurrence in clinical cases. Most published methods in this area either are inaccurate or require lots of manual interactions. Motivated by the state-of-the-art general mesh segmentation methods that adopted the theory of harmonic field to detect partition boundaries, this paper proposes a novel, dental-targeted segmentation framework for dental meshes. With a specially designed weighting scheme and a strategy of a priori knowledge to guide the assignment of harmonic constraints, this method can identify teeth partition boundaries effectively. Extensive experiments and quantitative analysis demonstrate that the proposed method is able to partition high-quality teeth automatically with robustness and efficiency.
Constrained CVT Meshes and a Comparison of Triangular Mesh Generators
Nguyen, Hoa [Florida State University; Burkardt, John [Florida State University; Gunzburger, Max [Florida State University; Ju, Lili [University of South Carolina; Saka, Yuki [Florida State University
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.
Stochastic domain decomposition for time dependent adaptive mesh generation
Bihlo, Alexander; Walsh, Emily J
2015-01-01
The efficient generation of meshes is an important component in the numerical solution of problems in physics and engineering. Of interest are situations where global mesh quality and a tight coupling to the solution of the physical partial differential equation (PDE) is important. We consider parabolic PDE mesh generation and present a method for the construction of adaptive meshes in two spatial dimensions using stochastic domain decomposition that is suitable for an implementation in a multi- or many-core environment. Methods for mesh generation on periodic domains are also provided. The mesh generator is coupled to a time dependent physical PDE and the system is evolved using an alternating solution procedure. The method uses the stochastic representation of the exact solution of a parabolic linear mesh generator to find the location of an adaptive mesh along the (artificial) subdomain interfaces. The deterministic evaluation of the mesh over each subdomain can then be obtained completely independently us...
An Adaptive Mesh Algorithm: Mesh Structure and Generation
Scannapieco, Anthony J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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.
CUBIT mesh generation environment. Volume 1: Users manual
Blacker, T.D.; Bohnhoff, W.J.; Edwards, T.L. [and others
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.
Polygonal Prism Mesh in the Viscous Layers for the Polyhedral Mesh Generator, PolyGen
Polyhedral mesh has been known to have some benefits over the tetrahedral mesh. Efforts have been made to set up a polyhedral mesh generation system with open source programs SALOME and TetGen. The evaluation has shown that the polyhedral mesh generation system is promising. But it is necessary to extend the capability of the system to handle the viscous layers to be a generalized mesh generator. A brief review to the previous works on the mesh generation for the viscous layers will be made in section 2. Several challenging issues for the polygonal prism mesh generation will be discussed as well. The procedure to generate a polygonal prism mesh will be discussed in detail in section 3. Conclusion will be followed in section 4. A procedure to generate meshes in the viscous layers with PolyGen has been successfully designed. But more efforts have to be exercised to find the best way for the generating meshes for viscous layers. Using the extrusion direction of the STL data will the first of the trials in the near future
Update on Development of Mesh Generation Algorithms in MeshKit
Jain, Rajeev [Argonne National Lab. (ANL), Argonne, IL (United States); Vanderzee, Evan [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay [Argonne National Lab. (ANL), Argonne, IL (United States)
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.
Automatic generation of documents
Rosa Gini; Jacopo Pasquini
2006-01-01
This paper describes a natural interaction between Stata and markup languages. Stata’s programming and analysis features, together with the flexibility in output formatting of markup languages, allow generation and/or update of whole documents (reports, presentations on screen or web, etc.). Examples are given for both LaTeX and HTML. Stata’s commands are mainly dedicated to analysis of data on a computer screen and output of analysis stored in a log file available to researchers for later re...
Automatic Generation of Technical Documentation
Reiter, Ehud; Mellish, Chris; Levine, John
1994-01-01
Natural-language generation (NLG) techniques can be used to automatically produce technical documentation from a domain knowledge base and linguistic and contextual models. We discuss this application of NLG technology from both a technical and a usefulness (costs and benefits) perspective. This discussion is based largely on our experiences with the IDAS documentation-generation project, and the reactions various interested people from industry have had to IDAS. We hope that this summary of ...
Image-Based Geometric Modeling and Mesh Generation
2013-01-01
As a new interdisciplinary research area, “image-based geometric modeling and mesh generation” integrates image processing, geometric modeling and mesh generation with finite element method (FEM) to solve problems in computational biomedicine, materials sciences and engineering. It is well known that FEM is currently well-developed and efficient, but mesh generation for complex geometries (e.g., the human body) still takes about 80% of the total analysis time and is the major obstacle to reduce the total computation time. It is mainly because none of the traditional approaches is sufficient to effectively construct finite element meshes for arbitrarily complicated domains, and generally a great deal of manual interaction is involved in mesh generation. This contributed volume, the first for such an interdisciplinary topic, collects the latest research by experts in this area. These papers cover a broad range of topics, including medical imaging, image alignment and segmentation, image-to-mesh conversion,...
Automatic Generation of Technical Documentation
Reiter, E R; Levine, J; Reiter, Ehud; Mellish, Chris; Levine, John
1994-01-01
Natural-language generation (NLG) techniques can be used to automatically produce technical documentation from a domain knowledge base and linguistic and contextual models. We discuss this application of NLG technology from both a technical and a usefulness (costs and benefits) perspective. This discussion is based largely on our experiences with the IDAS documentation-generation project, and the reactions various interested people from industry have had to IDAS. We hope that this summary of our experiences with IDAS and the lessons we have learned from it will be beneficial for other researchers who wish to build technical-documentation generation systems.
STL Triangular Mesh Generation Based on SAT Model
Yuwei Zhang
2013-06-01
Full Text Available Mesh generation is a fundamental technique in multiple domains. In this study, a STL triangular mesh generation method based on SAT model is proposed. Two novel triangulation methods, the constrained Delaunay algorithm and the grid subtraction algorithm, are employed on the multi-loop planer regions and the curved surfaces respectively. For the use of node adjustment, the mesh nodes on the surface boundary are strictly matched, with no cracks created on the joint of model surfaces. Experiments show that the proposed solution works effectively and high quality of the mesh model is achieved.
Balaven-Clermidy, S.
2001-12-01
Oil reservoir simulations study multiphase flows in porous media. These flows are described and evaluated through numerical schemes on a discretization of the reservoir domain. In this thesis, we were interested in this spatial discretization and a new kind of hybrid mesh has been proposed where the radial nature of flows in the vicinity of wells is directly taken into account in the geometry. Our modular approach described wells and their drainage area through radial circular meshes. These well meshes are inserted in a structured reservoir mesh (a Corner Point Geometry mesh) made up with hexahedral cells. Finally, in order to generate a global conforming mesh, proper connections are realized between the different kinds of meshes through unstructured transition ones. To compute these transition meshes that we want acceptable in terms of finite volume methods, an automatic method based on power diagrams has been developed. Our approach can deal with a homogeneous anisotropic medium and allows the user to insert vertical or horizontal wells as well as secondary faults in the reservoir mesh. Our work has been implemented, tested and validated in 2D and 2D1/2. It can also be extended in 3D when the geometrical constraints are simplicial ones: points, segments and triangles. (author)
METHOD FOR ADAPTIVE MESH GENERATION BASED ON GEOMETRICAL FEATURES OF 3D SOLID
HUANG Xiaodong; DU Qungui; YE Bangyan
2006-01-01
In order to provide a guidance to specify the element size dynamically during adaptive finite element mesh generation, adaptive criteria are firstly defined according to the relationships between the geometrical features and the elements of 3D solid. Various modes based on different datum geometrical elements, such as vertex, curve, surface, and so on, are then designed for generating local refmed mesh. With the guidance of the defined criteria, different modes are automatically selected to apply on the appropriate datum objects to program the element size in the local special areas. As a result, the control information of element size is successfully programmed coveting the entire domain based on the geometrical features of 3D solid. A new algorithm based on Delaunay triangulation is then developed for generating 3D adaptive fmite element mesh, in which the element size is dynamically specified to catch the geometrical features and suitable tetrahedron facets are selected to locate interior nodes continuously. As a result, adaptive mesh with good-quality elements is generated. Examples show that the proposed method can be successfully applied to adaptive finite element mesh automatic generation based on the geometrical features of 3D solid.
Towards Unstructured Mesh Generation Using the Inverse Poisson Problem
Bunin, Guy
2008-01-01
A novel approach to unstructured quadrilateral mesh generation for planar domains is presented. Away from irregular vertices, the resulting meshes have the properties of nearly conformal grids. The technique is based on a theoretical relation between the present problem, and the inverse Poisson (IP) problem with point sources. An IP algorithm is described, which constructs a point-source distribution, whose sources correspond to the irregular vertices of the mesh. Both the background theory a...
Hex-dominant mesh generation for basin modeling with complex geometry
Basin modeling aims to reconstruct the geological history of a basin and its oil system by means of fluid flow simulations, which is done by using a series of meshes describing basin geometry at each geological instant. These meshes are preferably hexahedral rather than tetrahedral in virtue for better numerical results. The basin can simply consist of geological layers delimited one from another by horizons. It can be geometrically complex with one or more faults interrupting the layers, which is barely studied but increasingly demanded. This paper exposes an automatic method which generates hex-dominant meshes for basin modeling with complex geometry. Firstly, based on their triangulations at the latest instant, 3D surface grids are generated with identical topology for all the horizons, and with some quadrilaterals being split across the diagonals to adapt to fault traces. Afterwards, all instants are iterated to generate corresponding meshes by firstly applying horizon and fault displacement on the mesh generated for precedent instant; the method then connects the bottom and top surface grids of the new layer along corresponding nodes, and splits certain cells along faults when necessary. Simulations have been carried out on generated meshes with satisfactory results.
Robust Generation of Signed Distance Fields from Triangle Meshes
Bærentzen, Jakob Andreas
A new method for robust generation of distance fields from triangle meshes is presented. Graphics hardware is used to accelerate a technique for generating layered depth images. From multiple layered depth images, a binary volume and a point representation are extracted. The point information is...... iso-surface of the distance field and fit it to the point set. Using this method, one may recover sharp edge information. Examples are given where the method for generating distance fields coupled with mesh fitting is used to perform Boolean and morphological operations on triangle meshes....
Finite Element Meshes Auto-Generation for the Welted Bifurcation
YUANMei; LIYa-ping
2004-01-01
In this paper, firstly, a mathematical model for a specific kind of welted bifurcation is established, the parametric equation for the intersecting curve is resulted in. Secondly, a method for partitioning finite element meshes of the welted bifurcation is put forward, its main idea is that developing the main pipe surface and the branch pipe surface respectively, dividing meshes on each developing plane and obtaining meshes points, then transforming their plane coordinates into space coordinates. Finally, an applied program for finite element meshes auto-generation is simply introduced, which adopt ObjectARX technique and its running result can be shown in AutoCAD. The meshes generated in AutoCAD can be exported conveniently to most of finite element analysis soft wares, and the finite element computing result can satisfy the engineering precision requirement.
Delaunay mesh generation for an unstructured-grid ocean general circulation model
Legrand, S.; Legat, V.; E. Deleersnijder
2000-01-01
An incremental method is presented to generate automatically boundary-fitted Delaunay triangulations of the global ocean. The method takes into account Earth curvature and allows local mesh refinement in order to resolve topological or dynamical features like midocean ridges or western boundary currents. Crucial issues like the nodes insertion process, the boundary integrity problem or the creation of inner nodes are explained. Finally, the quality of generated triangulations is discussed.
Using Multi-threading for the Automatic Load Balancing of 2D Adaptive Finite Element Meshes
Heber, Gerd; Biswas, Rupak; Thulasiraman, Parimala; Gao, Guang R.; Saini, Subhash (Technical Monitor)
1998-01-01
In this paper, we present a multi-threaded approach for the automatic load balancing of adaptive finite element (FE) meshes The platform of our choice is the EARTH multi-threaded system which offers sufficient capabilities to tackle this problem. We implement the adaption phase of FE applications oil triangular meshes and exploit the EARTH token mechanism to automatically balance the resulting irregular and highly nonuniform workload. We discuss the results of our experiments oil EARTH-SP2, on implementation of EARTH on the IBM SP2 with different load balancing strategies that are built into the runtime system.
Hexahedral mesh generation via the dual arrangement of surfaces
Mitchell, S.A.; Tautges, T.J. [Sandia National Labs., Albuquerque, NM (United States)
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.
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.
Mesh generation technology for nuclear reactor simulation; barriers and opportunities
Mesh generation in support of nuclear reactor simulation has much in common with the requirements of other application areas, such as computational fluid dynamics (CFD). Indeed, fluid dynamics analysis of the coolant behavior inside the reactor core is an internal flow problem that requires the resolution of spatial and temporal variations in the flow caused by complex component configurations, fluids/structure interaction, turbulence, and thermal heating of the coolant. Typical concerns of meshing complex geometries; the use of hexahedral vs. tetrahedral elements, element geometric quality, mesh smoothness, use of anisotropic elements in the thermal boundary layer, etc., are all considerations important to the reactor meshing problem. Reactor meshing begins to become more specialized as the need to employ reactor simulation as a predictive design and safety analysis capability grows in importance. First, a predictive capability will require more precise physical models to be included, and these models will need to be supported by a computational science framework that will allow them to be accurately approximated both spatially and temporally during the reactor core analysis. Both the multiphysical nature of the composite reactor model and details of the physics algorithms themselves will place new requirements on the meshing process needed to support multidimensional reactor simulation. This article discusses the current state of meshing technology applied to reactor simulation and examines a set of issues that are important in the generation of high-quality reactor meshes today and in the future
Medical Image Processing for Fully Integrated Subject Specific Whole Brain Mesh Generation
Chih-Yang Hsu
2015-05-01
Full Text Available Currently, anatomically consistent segmentation of vascular trees acquired with magnetic resonance imaging requires the use of multiple image processing steps, which, in turn, depend on manual intervention. In effect, segmentation of vascular trees from medical images is time consuming and error prone due to the tortuous geometry and weak signal in small blood vessels. To overcome errors and accelerate the image processing time, we introduce an automatic image processing pipeline for constructing subject specific computational meshes for entire cerebral vasculature, including segmentation of ancillary structures; the grey and white matter, cerebrospinal fluid space, skull, and scalp. To demonstrate the validity of the new pipeline, we segmented the entire intracranial compartment with special attention of the angioarchitecture from magnetic resonance imaging acquired for two healthy volunteers. The raw images were processed through our pipeline for automatic segmentation and mesh generation. Due to partial volume effect and finite resolution, the computational meshes intersect with each other at respective interfaces. To eliminate anatomically inconsistent overlap, we utilized morphological operations to separate the structures with a physiologically sound gap spaces. The resulting meshes exhibit anatomically correct spatial extent and relative positions without intersections. For validation, we computed critical biometrics of the angioarchitecture, the cortical surfaces, ventricular system, and cerebrospinal fluid (CSF spaces and compared against literature values. Volumina and surface areas of the computational mesh were found to be in physiological ranges. In conclusion, we present an automatic image processing pipeline to automate the segmentation of the main intracranial compartments including a subject-specific vascular trees. These computational meshes can be used in 3D immersive visualization for diagnosis, surgery planning with haptics
Automatic generation of tourist brochures
Birsak, Michael
2014-05-01
We present a novel framework for the automatic generation of tourist brochures that include routing instructions and additional information presented in the form of so-called detail lenses. The first contribution of this paper is the automatic creation of layouts for the brochures. Our approach is based on the minimization of an energy function that combines multiple goals: positioning of the lenses as close as possible to the corresponding region shown in an overview map, keeping the number of lenses low, and an efficient numbering of the lenses. The second contribution is a route-aware simplification of the graph of streets used for traveling between the points of interest (POIs). This is done by reducing the graph consisting of all shortest paths through the minimization of an energy function. The output is a subset of street segments that enable traveling between all the POIs without considerable detours, while at the same time guaranteeing a clutter-free visualization. © 2014 The Author(s) Computer Graphics Forum © 2014 The Eurographics Association and John Wiley & Sons Ltd. Published by John Wiley & Sons Ltd.
Automatic Tooth Segmentation of Dental Mesh Based on Harmonic Fields
Sheng-hui Liao; Shi-jian Liu; Bei-ji Zou; Xi Ding; Ye Liang; Jun-hui Huang
2015-01-01
An important preprocess in computer-aided orthodontics is to segment teeth from the dental models accurately, which should involve manual interactions as few as possible. But fully automatic partition of all teeth is not a trivial task, since teeth occur in different shapes and their arrangements vary substantially from one individual to another. The difficulty is exacerbated when severe teeth malocclusion and crowding problems occur, which is a common occurrence in clinical cases. Most publi...
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
Chi Wan Lim
Full Text Available We propose an automatic algorithm for the reconstruction of patient-specific cardiac mesh models with 1-to-1 vertex correspondence. In this framework, a series of 3D meshes depicting the endocardial surface of the heart at each time step is constructed, based on a set of border delineated magnetic resonance imaging (MRI data of the whole cardiac cycle. The key contribution in this work involves a novel reconstruction technique to generate a 4D (i.e., spatial-temporal model of the heart with 1-to-1 vertex mapping throughout the time frames. The reconstructed 3D model from the first time step is used as a base template model and then deformed to fit the segmented contours from the subsequent time steps. A method to determine a tree-based connectivity relationship is proposed to ensure robust mapping during mesh deformation. The novel feature is the ability to handle intra- and inter-frame 2D topology changes of the contours, which manifests as a series of merging and splitting of contours when the images are viewed either in a spatial or temporal sequence. Our algorithm has been tested on five acquisitions of cardiac MRI and can successfully reconstruct the full 4D heart model in around 30 minutes per subject. The generated 4D heart model conforms very well with the input segmented contours and the mesh element shape is of reasonably good quality. The work is important in the support of downstream computational simulation activities.
ORMGEN3D, 3-D Crack Geometry FEM Mesh Generator
1 - Description of program or function: ORMGEN3D is a finite element mesh generator for computational fracture mechanics analysis. The program automatically generates a three-dimensional finite element model for six different crack geometries. These geometries include flat plates with straight or curved surface cracks and cylinders with part-through cracks on the outer or inner surface. Mathematical or user-defined crack shapes may be considered. The curved cracks may be semicircular, semi-elliptical, or user-defined. A cladding option is available that allows for either an embedded or penetrating crack in the clad material. 2 - Method of solution: In general, one eighth or one-quarter of the structure is modelled depending on the configuration or option selected. The program generates a core of special wedge or collapsed prism elements at the crack front to introduce the appropriate stress singularity at the crack tip. The remainder of the structure is modelled with conventional 20-node iso-parametric brick elements. Element group I of the finite element model consists of an inner core of special crack tip elements surrounding the crack front enclosed by a single layer of conventional brick elements. Eight element divisions are used in a plane orthogonal to the crack front, while the number of element divisions along the arc length of the crack front is user-specified. The remaining conventional brick elements of the model constitute element group II. 3 - Restrictions on the complexity of the problem: Maxima of 5,500 nodes, 4 layers of clad elements
Robust Generation of Signed Distance Fields from Triangle Meshes
Bærentzen, Jakob Andreas
2005-01-01
A new method for robust generation of distance fields from triangle meshes is presented. Graphics hardware is used to accelerate a technique for generating layered depth images. From multiple layered depth images, a binary volume and a point representation are extracted. The point information is...... then used to convert the binary volume into a distance field. The method is robust and handles holes, spurious triangles and ambiguities. Moreover, the method lends itself to Boolean operations between solids. Since a point cloud as well as a signed distance is generated, it is possible to extract an...... iso-surface of the distance field and fit it to the point set. Using this method, one may recover sharp edge information. Examples are given where the method for generating distance fields coupled with mesh fitting is used to perform Boolean and morphological operations on triangle meshes....
Adaptive mesh refinement and automatic remeshing in crystal plasticity finite element simulations
In finite element simulations dedicated to the modelling of microstructure evolution, the mesh has to be fine enough to: (i) accurately describe the geometry of the constituents; (ii) capture local strain gradients stemming from the heterogeneity in material properties. In this paper, 3D polycrystalline aggregates are discretized into unstructured meshes and a level set framework is used to represent the grain boundaries. The crystal plasticity finite element method is used to simulate the plastic deformation of these aggregates. A mesh sensitivity analysis based on the deformation energy distribution shows that the predictions are, on average, more sensitive near grain boundaries. An anisotropic mesh refinement strategy based on the level set description is introduced and it is shown that it offers a good compromise between accuracy requirements on the one hand and computation time on the other hand. As the aggregates deform, mesh distortion inevitably occurs and ultimately causes the breakdown of the simulations. An automatic remeshing tool is used to periodically reconstruct the mesh and appropriate transfer of state variables is performed. It is shown that the diffusion related to data transfer is not significant. Finally, remeshing is performed repeatedly in a highly resolved 500 grains polycrystal subjected to about 90% thickness reduction in rolling. The predicted texture is compared with the experimental data and with the predictions of a standard Taylor model
Development of unstructured mesh generator on parallel computers
A general-purpose unstructured mesh generator, 'GRID3D/UNST', has been developed on parallel computers. High-speed operations and large-scale memory capacity of parallel computers enable the system to generate a large-scale mesh at high speed. As a matter of fact, the system generates large-scale mesh composed of 2,400,000 nodes and 14,000,000 elements about 1.5 hours on HITACHI SR2201, 64 PEs (Processing Elements) through 2.5 hours pre-process on SUN. Also the system is built on standard FORTRAN, C and Motif, and therefore has high portability. The system enables us to solve a large-scale problem that has been impossible to be solved, and to break new ground in the field of science and engineering. (author)
Generating Signed Distance Fields From Triangle Meshes
Bærentzen, Jakob Andreas; Aanæs, Henrik
A method for generating a discrete, signed 3D distance field is proposed. Distance fields are used in a number of contexts. In particular the popular level set method is usually initialized by a distance field. The main focus of our work is on simplifying the computation of the sign when generating...... leads to a method for generating signed distance fields which is a simple and straightforward extension of the method for generating unsigned distance fields. We prove that our choice of pseudo normal leads to a correct technique for computing the sign....
Traceability Through Automatic Program Generation
Richardson, Julian; Green, Jeff
2003-01-01
Program synthesis is a technique for automatically deriving programs from specifications of their behavior. One of the arguments made in favour of program synthesis is that it allows one to trace from the specification to the program. One way in which traceability information can be derived is to augment the program synthesis system so that manipulations and calculations it carries out during the synthesis process are annotated with information on what the manipulations and calculations were and why they were made. This information is then accumulated throughout the synthesis process, at the end of which, every artifact produced by the synthesis is annotated with a complete history relating it to every other artifact (including the source specification) which influenced its construction. This approach requires modification of the entire synthesis system - which is labor-intensive and hard to do without influencing its behavior. In this paper, we introduce a novel, lightweight technique for deriving traceability from a program specification to the corresponding synthesized code. Once a program has been successfully synthesized from a specification, small changes are systematically made to the specification and the effects on the synthesized program observed. We have partially automated the technique and applied it in an experiment to one of our program synthesis systems, AUTOFILTER, and to the GNU C compiler, GCC. The results are promising: 1. Manual inspection of the results indicates that most of the connections derived from the source (a specification in the case of AUTOFILTER, C source code in the case of GCC) to its generated target (C source code in the case of AUTOFILTER, assembly language code in the case of GCC) are correct. 2. Around half of the lines in the target can be traced to at least one line of the source. 3. Small changes in the source often induce only small changes in the target.
Computational mesh generation for vascular structures with deformable surfaces
Computational blood flow and vessel wall mechanics simulations for vascular structures are becoming an important research tool for patient-specific surgical planning and intervention. An important step in the modelling process for patient-specific simulations is the creation of the computational mesh based on the segmented geometry. Most known solutions either require a large amount of manual processing or lead to a substantial difference between the segmented object and the actual computational domain. We have developed a chain of algorithms that lead to a closely related implementation of image segmentation with deformable models and 3D mesh generation. The resulting processing chain is very robust and leads both to an accurate geometrical representation of the vascular structure as well as high quality computational meshes. The chain of algorithms has been tested on a wide variety of shapes. A benchmark comparison of our mesh generation application with five other available meshing applications clearly indicates that the new approach outperforms the existing methods in the majority of cases. (orig.)
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
Aranha: a 2D mesh generator for triangular finite elements
A method for generating unstructured meshes for linear and quadratic triangular finite elements is described in this paper. Some topics on the C language data structure used in the development of the program Aranha are also presented. The applicability for adaptive remeshing is shown and finally several examples are included to illustrate the performance of the method in irregular connected planar domains. (author)
Automatic mesh adaptivity for CADIS and FW-CADIS neutronics modeling of difficult shielding problems
The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. First, a macro-material approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm de-couples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility. Using these algorithms resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, obviating the need for a world-class super computer. (authors)
Conforming restricted Delaunay mesh generation for piecewise smooth complexes
Engwirda, Darren
2016-01-01
A Frontal-Delaunay refinement algorithm for mesh generation in piecewise smooth domains is described. Built using a restricted Delaunay framework, this new algorithm combines a number of novel features, including: (i) a consistent, conforming restricted Delaunay representation for domains specified as a (non-manifold) collection of piecewise smooth surface patches and curve constraints, (ii) a `protection' strategy for domains containing 1-dimensional features that meet at sharply acute angle...
AUTOMATIC CAPTION GENERATION FOR ELECTRONICS TEXTBOOKS
Veena Thakur; Trupti Gedam
2015-01-01
Automatic or semi-automatic approaches for developing Technology Supported Learning Systems (TSLS) are required to lighten their development cost. The main objective of this paper is to automate the generation of a caption module; it aims at reproducing the way teachers prepare their lessons and the learning material they will use throughout the course. Teachers tend to choose one or more textbooks that cover the contents of their subjects, determine the topics to be addressed, and identify...
The ACR-program for automatic finite element model generation for part through cracks
The ACR-program (Automatic Finite Element Model Generation for Part Through Cracks) has been developed at the Technical Research Centre of Finland (VTT) for automatic finite element model generation for surface flaws using three dimensional solid elements. Circumferential or axial cracks can be generated on the inner or outer surface of a cylindrical or toroidal geometry. Several crack forms are available including the standard semi-elliptical surface crack. The program can be used in the development of automated systems for fracture mechanical analyses of structures. The tests for the accuracy of the FE-mesh have been started with two-dimensional models. The results indicate that the accuracy of the standard mesh is sufficient for practical analyses. Refinement of the standard mesh is needed in analyses with high load levels well over the limit load of the structure
Terrain-driven unstructured mesh development through semi-automatic vertical feature extraction
Bilskie, Matthew V.; Coggin, David; Hagen, Scott C.; Medeiros, Stephen C.
2015-12-01
validation techniques are necessary for state-of-the-art flood inundation models. In addition, the semi-automated, unstructured mesh generation process presented herein increases the overall accuracy of simulated storm surge across the floodplain without reliance on hand digitization or sacrificing computational cost.
Automatic generation of multilingual sports summaries
Hasan, Fahim Muhammad
2011-01-01
Natural Language Generation is a subfield of Natural Language Processing, which is concerned with automatically creating human readable text from non-linguistic forms of information. A template-based approach to Natural Language Generation utilizes base formats for different types of sentences, which are subsequently transformed to create the final readable forms of the output. In this thesis, we investigate the suitability of a template-based approach to multilingual Natural Language Generat...
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.
Exploiting MeSH indexing in MEDLINE to generate a data set for word sense disambiguation
McInnes Bridget T
2011-06-01
Full Text Available Abstract Background Evaluation of Word Sense Disambiguation (WSD methods in the biomedical domain is difficult because the available resources are either too small or too focused on specific types of entities (e.g. diseases or genes. We present a method that can be used to automatically develop a WSD test collection using the Unified Medical Language System (UMLS Metathesaurus and the manual MeSH indexing of MEDLINE. We demonstrate the use of this method by developing such a data set, called MSH WSD. Methods In our method, the Metathesaurus is first screened to identify ambiguous terms whose possible senses consist of two or more MeSH headings. We then use each ambiguous term and its corresponding MeSH heading to extract MEDLINE citations where the term and only one of the MeSH headings co-occur. The term found in the MEDLINE citation is automatically assigned the UMLS CUI linked to the MeSH heading. Each instance has been assigned a UMLS Concept Unique Identifier (CUI. We compare the characteristics of the MSH WSD data set to the previously existing NLM WSD data set. Results The resulting MSH WSD data set consists of 106 ambiguous abbreviations, 88 ambiguous terms and 9 which are a combination of both, for a total of 203 ambiguous entities. For each ambiguous term/abbreviation, the data set contains a maximum of 100 instances per sense obtained from MEDLINE. We evaluated the reliability of the MSH WSD data set using existing knowledge-based methods and compared their performance to that of the results previously obtained by these algorithms on the pre-existing data set, NLM WSD. We show that the knowledge-based methods achieve different results but keep their relative performance except for the Journal Descriptor Indexing (JDI method, whose performance is below the other methods. Conclusions The MSH WSD data set allows the evaluation of WSD algorithms in the biomedical domain. Compared to previously existing data sets, MSH WSD contains a larger
Techniques on mesh generation for the brain shift simulation
Lobos, Claudio; Payan, Yohan; Hitschfeld, Nancy
2007-01-01
Neurosurgery interventions involve complex tracking systems because a tissue deformation takesplace. The neuronavigation system relies only on preoperative images. In order to overcome the soft tissue deformations and guarantee the accuracy of the navigation a biomechanical model can be used during surgery to simulate the deformation of the brain. Therefore, a mesh generation for an optimal real-time Finite Element Model (FEM) becomes crucial. In this work we present different alternatives from a meshgeneration point of view that were evaluated to optimize the process in terms of elements quantity and quality as well as constraints of a intraoperative application and patient specific data.
Generating Semi-Markov Models Automatically
Johnson, Sally C.
1990-01-01
Abstract Semi-Markov Specification Interface to SURE Tool (ASSIST) program developed to generate semi-Markov model automatically from description in abstract, high-level language. ASSIST reads input file describing failure behavior of system in abstract language and generates Markov models in format needed for input to Semi-Markov Unreliability Range Evaluator (SURE) program (COSMIC program LAR-13789). Facilitates analysis of behavior of fault-tolerant computer. Written in PASCAL.
A Novel Tetrahedral Mesh Generation Method for Rotating Machines Including End-Coil Region
Yamashita, Hideo; Yamaji, Akihisa; Cingoski, Vlatko; Kaneda, Kazufumi
1996-01-01
In this paper, a novel method for generating tetrahedral finite-element meshes suitable for 3-D finite element analysis of rotating machines is presented. The proposed method enables the easy development of 3-D meshes for various rotating machines, especially in the end-coil region and the surrounding air region. Tessellation of the 3-D region is made possible by simple extension of a previously generated 2-D triangular mesh, used as a model mesh, into the third dimension.
A GENERATIVE CAD MODEL OF A WORM GEAR MESHING
Angelika WRONKOWICZ
2014-03-01
Full Text Available This article introduces the term of a generative CAD model, its origins and, thus, a need of creating such a type of models. A process of generative model creation as well as specific forms of knowledge recording applied in the implementation phase in various CAD systems are briefly discussed. The example of a worm gear meshing realized by the CATIA software encapsulates the methodology of generative model construction. Sources and types of knowledge for design and construction required for development of the aforementioned model as well as the UML language as a method of formal knowledge recording are presented. The concept of model creation, i.e. assumptions and the structure as well as logic of the model operation are described. Also, the paper addresses selected elements of the project that present the manner in which the model was constructed.
Unstructured Mesh Movement and Viscous Mesh Generation for CFD-Based Design Optimization Project
National Aeronautics and Space Administration — The innovations proposed are twofold: 1) a robust unstructured mesh movement method able to handle isotropic (Euler), anisotropic (viscous), mixed element (hybrid)...
Group-wise automatic mesh-based analysis of cortical thickness
Vachet, Clement; Cody Hazlett, Heather; Niethammer, Marc; Oguz, Ipek; Cates, Joshua; Whitaker, Ross; Piven, Joseph; Styner, Martin
2011-03-01
The analysis of neuroimaging data from pediatric populations presents several challenges. There are normal variations in brain shape from infancy to adulthood and normal developmental changes related to tissue maturation. Measurement of cortical thickness is one important way to analyze such developmental tissue changes. We developed a novel framework that allows group-wise automatic mesh-based analysis of cortical thickness. Our approach is divided into four main parts. First an individual pre-processing pipeline is applied on each subject to create genus-zero inflated white matter cortical surfaces with cortical thickness measurements. The second part performs an entropy-based group-wise shape correspondence on these meshes using a particle system, which establishes a trade-off between an even sampling of the cortical surfaces and the similarity of corresponding points across the population using sulcal depth information and spatial proximity. A novel automatic initial particle sampling is performed using a matched 98-lobe parcellation map prior to a particle-splitting phase. Third, corresponding re-sampled surfaces are computed with interpolated cortical thickness measurements, which are finally analyzed via a statistical vertex-wise analysis module. This framework consists of a pipeline of automated 3D Slicer compatible modules. It has been tested on a small pediatric dataset and incorporated in an open-source C++ based high-level module called GAMBIT. GAMBIT's setup allows efficient batch processing, grid computing and quality control. The current research focuses on the use of an average template for correspondence and surface re-sampling, as well as thorough validation of the framework and its application to clinical pediatric studies.
Moving mesh generation with a sequential approach for solving PDEs
physical and mesh equations suffers typically from long computation time due to highly nonlinear coupling between the two equations. Moreover, the extended system (physical and mesh equations) may be sensitive to the tuning parameters such as a temporal relaxation factor. It is therefore useful to design a......In moving mesh methods, physical PDEs and a mesh equation derived from equidistribution of an error metrics (so-called the monitor function) are simultaneously solved and meshes are dynamically concentrated on steep regions (Lim et al., 2001). However, the simultaneous solution procedure of...... adaptive grid method (local refinement by adding/deleting the meshes at a discrete time level) as well as of efficiency for the dynamic adaptive grid method (or moving mesh method) where the number of meshes is not changed. For illustration, a phase change problem is solved with the decomposition algorithm....
Automatic Test Pattern Generation for Digital Circuits
S. Hemalatha
2014-04-01
Full Text Available Digital circuits complexity and density are increasing and at the same time it should have more quality and reliability. It leads with high test costs and makes the validation more complex. The main aim is to develop a complete behavioral fault simulation and automatic test pattern generation (ATPG system for digital circuits modeled in verilog and VHDL. An integrated Automatic Test Generation (ATG and Automatic Test Executing/Equipment (ATE system for complex boards is developed here. An approach to use memristors (resistors with memory in programmable analog circuits. The Main idea consists in a circuit design in which low voltages are applied to memristors during their operation as analog circuit elements and high voltages are used to program the memristor’s states. This way, as it was demonstrated in recent experiments, the state of memristors does not essentially change during analog mode operation. As an example of our approach, we have built several programmable analog circuits demonstrating memristor -based programming of threshold, gain and frequency. In these circuits the role of memristor is played by a memristor emulator developed by us. A multiplexer is developed to generate a class of minimum transition sequences. The entire hardware is realized as digital logical circuits and the test results are simulated in Model sim software. The results of this research show that behavioral fault simulation will remain as a highly attractive alternative for the future generation of VLSI and system-on-chips (SoC.
Different Manhattan project: automatic statistical model generation
Yap, Chee Keng; Biermann, Henning; Hertzmann, Aaron; Li, Chen; Meyer, Jon; Pao, Hsing-Kuo; Paxia, Salvatore
2002-03-01
We address the automatic generation of large geometric models. This is important in visualization for several reasons. First, many applications need access to large but interesting data models. Second, we often need such data sets with particular characteristics (e.g., urban models, park and recreation landscape). Thus we need the ability to generate models with different parameters. We propose a new approach for generating such models. It is based on a top-down propagation of statistical parameters. We illustrate the method in the generation of a statistical model of Manhattan. But the method is generally applicable in the generation of models of large geographical regions. Our work is related to the literature on generating complex natural scenes (smoke, forests, etc) based on procedural descriptions. The difference in our approach stems from three characteristics: modeling with statistical parameters, integration of ground truth (actual map data), and a library-based approach for texture mapping.
Linguistics Computation, Automatic Model Generation, and Intensions
Nourani, Cyrus F.
1994-01-01
Techniques are presented for defining models of computational linguistics theories. The methods of generalized diagrams that were developed by this author for modeling artificial intelligence planning and reasoning are shown to be applicable to models of computation of linguistics theories. It is shown that for extensional and intensional interpretations, models can be generated automatically which assign meaning to computations of linguistics theories for natural languages. Keywords: Computa...
XML-Based Automatic Test Data Generation
Halil Ibrahim Bulbul; Turgut Bakir
2012-01-01
Software engineering aims at increasing quality and reliability while decreasing the cost of the software. Testing is one of the most time-consuming phases of the software development lifecycle. Improvement in software testing results in decrease in cost and increase in quality of the software. Automation in software testing is one of the most popular ways of software cost reduction and reliability improvement. In our work we propose a system called XML-based automatic test data generation th...
Automatic Caption Generation for Electronics Textbooks
Veena Thakur
2014-12-01
Full Text Available Automatic or semi-automatic approaches for developing Technology Supported Learning Systems (TSLS are required to lighten their development cost. The main objective of this paper is to automate the generation of a caption module; it aims at reproducing the way teachers prepare their lessons and the learning material they will use throughout the course. Teachers tend to choose one or more textbooks that cover the contents of their subjects, determine the topics to be addressed, and identify the parts of the textbooks which may be helpful for the students it describes the entities, attributes, role and their relationship plus the constraints that govern the problem domain. The caption model is created in order to represent the vocabulary and key concepts of the problem domain. The caption model also identifies the relationships among all the entities within the scope of the problem domain, and commonly identifies their attributes. It defines a vocabulary and is helpful as a communication tool. DOM-Sortze, a framework that enables the semi-automatic generation of the Caption Module for technology supported learning system (TSLS from electronic textbooks. The semiautomatic generation of the Caption Module entails the identification and elicitation of knowledge from the documents to which end Natural Language Processing (NLP techniques are combined with ontologies and heuristic reasoning.
AUTOMATIC CAPTION GENERATION FOR ELECTRONICS TEXTBOOKS
Veena Thakur
2015-10-01
Full Text Available Automatic or semi-automatic approaches for developing Technology Supported Learning Systems (TSLS are required to lighten their development cost. The main objective of this paper is to automate the generation of a caption module; it aims at reproducing the way teachers prepare their lessons and the learning material they will use throughout the course. Teachers tend to choose one or more textbooks that cover the contents of their subjects, determine the topics to be addressed, and identify the parts of the textbooks which may be helpful for the students it describes the entities, attributes, role and their relationship plus the constraints that govern the problem domain. The caption model is created in order to represent the vocabulary and key concepts of the problem domain. The caption model also identifies the relationships among all the entities within the scope of the problem domain, and commonly identifies their attributes. It defines a vocabulary and is helpful as a communication tool. DOM-Sortze, a framework that enables the semi-automatic generation of the Caption Module for technology supported learning system (TSLS from electronic textbooks. The semiautomatic generation of the Caption Module entails the identification and elicitation of knowledge from the documents to which end Natural Language Processing (NLP techniques are combined with ontologies and heuristic reasoning.
Semi-automatic construction of the Chinese-English MeSH using Web-based term translation method.
Lu, Wen-Hsiang; Lin, Shih-Jui; Chan, Yi-Che; Chen, Kuan-Hsi
2005-01-01
Due to language barrier, non-English users are unable to retrieve the most updated medical information from the U.S. authoritative medical websites, such as PubMed and MedlinePlus. A few cross-language medical information retrieval (CLMIR) systems have been utilizing MeSH (Medical Subject Heading) with multilingual thesaurus to bridge the gap. Unfortunately, MeSH has yet not been translated into traditional Chinese currently. We proposed a semi-automatic approach to constructing Chinese-English MeSH based on Web-based term translation. The system provides knowledge engineers with candidate terms mining from anchor texts and search-result pages. The result is encouraging. Currently, more than 19,000 Chinese-English MeSH entries have been complied. This thesaurus will be used in Chinese-English CLMIR in the future. PMID:16779085
Automatic generation of combinatorial test data
Zhang, Jian; Ma, Feifei
2014-01-01
This book reviews the state-of-the-art in combinatorial testing, with particular emphasis on the automatic generation of test data. It describes the most commonly used approaches in this area - including algebraic construction, greedy methods, evolutionary computation, constraint solving and optimization - and explains major algorithms with examples. In addition, the book lists a number of test generation tools, as well as benchmarks and applications. Addressing a multidisciplinary topic, it will be of particular interest to researchers and professionals in the areas of software testing, combi
Automatic generation of simple (statistical) exams
Grün, Bettina; Zeileis, Achim
2008-01-01
Package exams provides a framework for automatic generation of simple (statistical) exams. To employ the tools, users just need to supply a pool of exercises and a master file controlling the layout of the final PDF document. The exercises are specified in separate Sweave files (containing R code for data generation and LaTeX code for problem and solution description) and the master file is a LaTeX document with some additional control commands. This paper gives an overview on the main design...
Papadakis, A. P.; Georghiou, G. E.; Metaxas, A. C.
2008-12-01
A new adaptive mesh generator has been developed and used in the analysis of high-pressure gas discharges, such as avalanches and streamers, reducing computational times and computer memory needs significantly. The new adaptive mesh generator developed, uses normalized error indicators, varying from 0 to 1, to guarantee optimal mesh resolution for all carriers involved in the analysis. Furthermore, it uses h- and r-refinement techniques such as mesh jiggling, edge swapping and node addition/removal to develop an element quality improvement algorithm that improves the mesh quality significantly and a fast and accurate algorithm for interpolation between meshes. Finally, the mesh generator is applied in the characterization of the transition from a single electron to the avalanche and streamer discharges in high-voltage, high-pressure gas discharges for dc 1 mm gaps, RF 1 cm point-plane gaps and parallel-plate 40 MHz configurations, in ambient atmospheric air.
Papadakis, A P [Department of Electrical Engineering, Frederick University Cyprus, 7 Y Frederickou Street, Palouriotissa, Nicosia 1036 (Cyprus); Georghiou, G E [Department of Electrical and Computer Engineering, University of Cyprus, 75 Kallipoleos, PO Box 20577, 1678, Nicosia (Cyprus); Metaxas, A C [St John' s College, University of Cambridge, Cambridge, CB2 1TP (United Kingdom)], E-mail: eng.ap@frederick.ac.cy, E-mail: geg@ucy.ac.cy, E-mail: acm33@cam.ac.uk
2008-12-07
A new adaptive mesh generator has been developed and used in the analysis of high-pressure gas discharges, such as avalanches and streamers, reducing computational times and computer memory needs significantly. The new adaptive mesh generator developed, uses normalized error indicators, varying from 0 to 1, to guarantee optimal mesh resolution for all carriers involved in the analysis. Furthermore, it uses h- and r-refinement techniques such as mesh jiggling, edge swapping and node addition/removal to develop an element quality improvement algorithm that improves the mesh quality significantly and a fast and accurate algorithm for interpolation between meshes. Finally, the mesh generator is applied in the characterization of the transition from a single electron to the avalanche and streamer discharges in high-voltage, high-pressure gas discharges for dc 1 mm gaps, RF 1 cm point-plane gaps and parallel-plate 40 MHz configurations, in ambient atmospheric air.
Efficient computation of clipped Voronoi diagram for mesh generation
Yan, Dongming
2013-04-01
The Voronoi diagram is a fundamental geometric structure widely used in various fields, especially in computer graphics and geometry computing. For a set of points in a compact domain (i.e. a bounded and closed 2D region or a 3D volume), some Voronoi cells of their Voronoi diagram are infinite or partially outside of the domain, but in practice only the parts of the cells inside the domain are needed, as when computing the centroidal Voronoi tessellation. Such a Voronoi diagram confined to a compact domain is called a clipped Voronoi diagram. We present an efficient algorithm to compute the clipped Voronoi diagram for a set of sites with respect to a compact 2D region or a 3D volume. We also apply the proposed method to optimal mesh generation based on the centroidal Voronoi tessellation. Crown Copyright © 2011 Published by Elsevier Ltd. All rights reserved.
Automatic Metadata Generation using Associative Networks
Rodriguez, Marko A; Van de Sompel, Herbert
2008-01-01
In spite of its tremendous value, metadata is generally sparse and incomplete, thereby hampering the effectiveness of digital information services. Many of the existing mechanisms for the automated creation of metadata rely primarily on content analysis which can be costly and inefficient. The automatic metadata generation system proposed in this article leverages resource relationships generated from existing metadata as a medium for propagation from metadata-rich to metadata-poor resources. Because of its independence from content analysis, it can be applied to a wide variety of resource media types and is shown to be computationally inexpensive. The proposed method operates through two distinct phases. Occurrence and co-occurrence algorithms first generate an associative network of repository resources leveraging existing repository metadata. Second, using the associative network as a substrate, metadata associated with metadata-rich resources is propagated to metadata-poor resources by means of a discrete...
Automatic code generation for distributed robotic systems
Hetero Helix is a software environment which supports relatively large robotic system development projects. The environment supports a heterogeneous set of message-passing LAN-connected common-bus multiprocessors, but the programming model seen by software developers is a simple shared memory. The conceptual simplicity of shared memory makes it an extremely attractive programming model, especially in large projects where coordinating a large number of people can itself become a significant source of complexity. We present results from three system development efforts conducted at Oak Ridge National Laboratory over the past several years. Each of these efforts used automatic software generation to create 10 to 20 percent of the system
Automatic Quiz Generation for the Elderly.
Chen, Weiqin; Samuelsen, Jeanette
2015-01-01
According to the literature, ageing causes declines in sensory, perceptual, motor and cognitive abilities. The combination of reduced vision, hearing, memory and mobility contributes to isolation and depression. We argue that memory games have potential for enhancing the cognitive ability of the elderly and improving their life quality. In our earlier research, we designed tangible tabletop games to help the elderly remember and talk about the past. In this paper, we report on our further research in the automatic generation of quizzes based on Wikipedia and other online resources for entertainment and memory training of the elderly. PMID:26294527
h-Adaptive Mesh Generation using Electric Field Intensity Value as a Criterion (in Japanese)
Toyonaga, Kiyomi; Cingoski, Vlatko; Kaneda, Kazufumi; Yamashita, Hideo
1994-01-01
Finite mesh divisions are essential to obtain accurate solution of two dimensional electric field analysis. It requires the technical knowledge to generate a suitable fine mesh divisions. In electric field problem, analysts are usually interested in the electric field intensity and its distribution. In order to obtain electric field intensity with high-accuracy, we have developed and adaptive mesh generator using electric field intensity value as a criterion.
New Software Developments for Quality Mesh Generation and Optimization from Biomedical Imaging Data
Yu, Zeyun; Wang, Jun; Gao, Zhanheng; Xu, Ming; Hoshijima, Masahiko
2013-01-01
In this paper we present a new software toolkit for generating and optimizing surface and volumetric meshes from three-dimensional (3D) biomedical imaging data, targeted at image-based finite element analysis of some biomedical activities in a single material domain. Our toolkit includes a series of geometric processing algorithms including surface re-meshing and quality-guaranteed tetrahedral mesh generation and optimization. All methods described have been encapsulated into a user-friendly ...
Pamgen, a library for parallel generation of simple finite element meshes.
Foucar, James G.; Drake, Richard Roy; Hensinger, David M.; Gardiner, Thomas Anthony
2008-04-01
Generating finite-element meshes is a serious bottleneck for large parallel simulations. When mesh generation is limited to serial machines and element counts approach a billion, this bottleneck becomes a roadblock. Pamgen is a parallel mesh generation library that allows on-the-fly scalable generation of hexahedral and quadrilateral finite element meshes for several simple geometries. It has been used to generate more that 1.1 billion elements on 17,576 processors. Pamgen generates an unstructured finite element mesh on each processor at the start of a simulation. The mesh is specified by commands passed to the library as a 'C'-programming language string. The resulting mesh geometry, topology, and communication information can then be queried through an API. pamgen allows specification of boundary condition application regions using sidesets (element faces) and nodesets (collections of nodes). It supports several simple geometry types. It has multiple alternatives for mesh grading. It has several alternatives for the initial domain decomposition. Pamgen makes it easy to change details of the finite element mesh and is very useful for performance studies and scoping calculations.
Challenges in Second-Generation Wireless Mesh Networks
Thomas Huehn
2008-10-01
Full Text Available Wireless mesh networks have the potential to provide ubiquitous high-speed Internet access at low costs. The good news is that initial deployments of WiFi meshes show the feasibility of providing ubiquitous Internet connectivity. However, their performance is far below the necessary and achievable limit. Moreover, users' subscription in the existing meshes is dismal even though the technical challenges to get connectivity are low. This paper provides an overview of the current status of mesh networks' deployment, and highlights the technical, economical, and social challenges that need to be addressed in the next years. As a proof-of-principle study, we discuss the above-mentioned challenges with reference to three real networks: (i MagNets, an operator-driven planned two-tier mesh network; (ii Berlin Freifunk network as a pure community-driven single-tier network; (iii Weimar Freifunk network, also a community-driven but two-tier network.
Challenges in Second-Generation Wireless Mesh Networks
Pescapé Antonio
2008-01-01
Full Text Available Wireless mesh networks have the potential to provide ubiquitous high-speed Internet access at low costs. The good news is that initial deployments of WiFi meshes show the feasibility of providing ubiquitous Internet connectivity. However, their performance is far below the necessary and achievable limit. Moreover, users' subscription in the existing meshes is dismal even though the technical challenges to get connectivity are low. This paper provides an overview of the current status of mesh networks' deployment, and highlights the technical, economical, and social challenges that need to be addressed in the next years. As a proof-of-principle study, we discuss the above-mentioned challenges with reference to three real networks: (i MagNets, an operator-driven planned two-tier mesh network; (ii Berlin Freifunk network as a pure community-driven single-tier network; (iii Weimar Freifunk network, also a community-driven but two-tier network.
A Study on the Efficient Mesh Generation for Finite Element Analysis of Electric Machinery
Kim, Jin Tae [Hangul and Computer Co.,Ltd. (Korea); Chung, Tae Kyung [Chungang University (Korea); Kim, Hyeong Seok [Soonchunhyang University (Korea)
1999-04-01
To obtain more accurate result in the finite element analysis for electric machinery, it is important to have a mesh being of good quality. This paper describes a new technique of mesh generation for the finite element method. When the list of points defining the region of analysis is given, an appropriate distribution of interior points is generated first. Secondly the points are connected to form the triangles. Finally the connectivity data are used to reposition the interior points using laplacian smoothing and mesh relaxation technique. In this paper, a mesh searching technique of Lawson which modifies the start mesh is proposed in addition to the above three steps. This algorithm is simple and produces the meshes being of good quality with high speed in comparison with the existing one. (author). 16 refs., 10 figs., 2 tabs.
Unstructured Mesh Movement and Viscous Mesh Generation for CFD-Based Design Optimization Project
National Aeronautics and Space Administration — The innovations proposed by ResearchSouth are: 1) a robust method to automatically insert high quality anisotropic prismatic (viscous boundary layer) cells into any...
Automatic Testcase Generation for Flight Software
Bushnell, David Henry; Pasareanu, Corina; Mackey, Ryan M.
2008-01-01
The TacSat3 project is applying Integrated Systems Health Management (ISHM) technologies to an Air Force spacecraft for operational evaluation in space. The experiment will demonstrate the effectiveness and cost of ISHM and vehicle systems management (VSM) technologies through onboard operation for extended periods. We present two approaches to automatic testcase generation for ISHM: 1) A blackbox approach that views the system as a blackbox, and uses a grammar-based specification of the system's inputs to automatically generate *all* inputs that satisfy the specifications (up to prespecified limits); these inputs are then used to exercise the system. 2) A whitebox approach that performs analysis and testcase generation directly on a representation of the internal behaviour of the system under test. The enabling technologies for both these approaches are model checking and symbolic execution, as implemented in the Ames' Java PathFinder (JPF) tool suite. Model checking is an automated technique for software verification. Unlike simulation and testing which check only some of the system executions and therefore may miss errors, model checking exhaustively explores all possible executions. Symbolic execution evaluates programs with symbolic rather than concrete values and represents variable values as symbolic expressions. We are applying the blackbox approach to generating input scripts for the Spacecraft Command Language (SCL) from Interface and Control Systems. SCL is an embedded interpreter for controlling spacecraft systems. TacSat3 will be using SCL as the controller for its ISHM systems. We translated the SCL grammar into a program that outputs scripts conforming to the grammars. Running JPF on this program generates all legal input scripts up to a prespecified size. Script generation can also be targeted to specific parts of the grammar of interest to the developers. These scripts are then fed to the SCL Executive. ICS's in-house coverage tools will be run to
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.
Automatic tool path generation for finish machining
Kwok, Kwan S.; Loucks, C.S.; Driessen, B.J.
1997-03-01
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 diameter CBN 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 results. A right pyramid and an ellipsoid were scanned successfully with the adaptive algorithm.
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.
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.
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. (paper)
FLUOMEG: a planar finite difference mesh generator for fluid flow problems with parallel boundaries
A two- or three-dimensional finite difference mesh generator capable of discretizing subrectangular flow regions (planar coordinates) with arbitrarily shaped bottom contours (vertical dimension) was developed. This economical, interactive computer code, written in FORTRAN IV and employing DISSPLA software together with graphics terminal, generates first a planar rectangular grid of variable element density according to the geometry and local kinematic flow patterns of a given fluid flow problem. Then subrectangular areas are deleted to produce canals, tributaries, bays, and the like. For three-dimensional problems, arbitrary bathymetric profiles (river beds, channel cross section, ocean shoreline profiles, etc.) are approximated with grid lines forming steps of variable spacing. Furthermore, the code works as a preprocessor numbering the discrete elements and the nodal points. Prescribed values for the principal variables can be automatically assigned to solid as well as kinematic boundaries. Cabinet drawings aid in visualizing the complete flow domain. Input data requirements are necessary only to specify the spacing between grid lines, determine land regions that have to be excluded, and to identify boundary nodes. 15 figures, 2 tables
A multilevel adaptive mesh generation scheme using Kd-trees
Alfonso Limon
2009-04-01
Full Text Available We introduce a mesh refinement strategy for PDE based simulations that benefits from a multilevel decomposition. Using Harten's MRA in terms of Schroder-Pander linear multiresolution analysis [20], we are able to bound discontinuities in $mathbb{R}$. This MRA is extended to $mathbb{R}^n$ in terms of n-orthogonal linear transforms and utilized to identify cells that contain a codimension-one discontinuity. These refinement cells become leaf nodes in a balanced Kd-tree such that a local dyadic MRA is produced in $mathbb{R}^n$, while maintaining a minimal computational footprint. The nodes in the tree form an adaptive mesh whose density increases in the vicinity of a discontinuity.
Automatic Assignment of Non-Leaf MeSH Terms to Biomedical Articles.
Kavuluru, Ramakanth; Rios, Anthony
2015-01-01
Assigning labels from a hierarchical vocabulary is a well known special case of multi-label classification, often modeled to maximize micro F1-score. However, building accurate binary classifiers for poorly performing labels in the hierarchy can improve both micro and macro F1-scores. In this paper, we propose and evaluate classification strategies involving descendant node instances to build better binary classifiers for non-leaf labels with the use-case of assigning Medical Subject Headings (MeSH) to biomedical articles. Librarians at the National Library of Medicine tag each biomedical article to be indexed by their PubMed information system with terms from the MeSH terminology, a biomedical conceptual hierarchy with over 27,000 terms. Human indexers look at each article's full text to assign a set of most suitable MeSH terms for indexing it. Several recent automated attempts focused on using the article title and abstract text to identify MeSH terms for the corresponding article. Despite these attempts, it is observed that assigning MeSH terms corresponding to certain non-leaf nodes of the MeSH hierarchy is particularly challenging. Non-leaf nodes are very important as they constitute one third of the total number of MeSH terms. Here, we demonstrate the effectiveness of exploiting training examples of descendant terms of non-leaf nodes in improving the performance of conventional classifiers for the corresponding non-leaf MeSH terms. Specifically, we focus on reducing the false positives (FPs) caused due to descendant instances in traditional classifiers. Our methods are able to achieve a relative improvement of 7.5% in macro-F1 score while also increasing the micro-F1 score by 1.6% for a set of 500 non-leaf terms in the MeSH hierarchy. These results strongly indicate the critical role of incorporating hierarchical information in MeSH term prediction. To our knowledge, our effort is the first to demonstrate the role of hierarchical information in improving
Generating IDS Attack Pattern Automatically Based on Attack Tree
向尕; 曹元大
2003-01-01
Generating attack pattern automatically based on attack tree is studied. The extending definition of attack tree is proposed. And the algorithm of generating attack tree is presented. The method of generating attack pattern automatically based on attack tree is shown, which is tested by concrete attack instances. The results show that the algorithm is effective and efficient. In doing so, the efficiency of generating attack pattern is improved and the attack trees can be reused.
Adaptive mesh generation for non-steady state heat transport problems
Full text: The paper deals with the problem of mesh generation for the two-dimensional finite element modeling. The general objective of the work is development of the mesh adaptation method and its application to non-steady state heat transport processes. The main feature of the method is generation of new triangular or quadrilateral mesh at each iteration of the adaptation procedure. This generation is performed on the basis of information obtained from the previous iteration. The adaptation is based on the evaluation of the solution curvature, which is approximated using second spatial derivatives. Discrete Hessian of the solution is applied to generate the relevant discrete metric, which is next interpolated in the whole domain. The metric is defined by three parameters: stretching of elements in two orthogonal directions and the angle of the directions with respect to the coordinate system. Thus, the mesh can be refined or stretched in the selected parts of the domain and in a selected direction. The general idea of the developed adaptation method applied to steady state problems is described. Application of the method to non-steady state heat transport processes is described in the present paper. Mesh adaptation in non-steady state processes presents several difficulties, among which decision when re-meshing should be done and transport of information from the old mesh to the new mesh are the most important. An example of application of the mesh adaptation method to the processes, which are characterized by fast changes of heat transfer coefficient in the third kind boundary conditions and by strong inhomogeneity of heat transport, is described. Refs. 1 (author)
Automatic generation of a view to geographical database
Dunkars, Mats
2001-01-01
This thesis concerns object oriented modelling and automatic generalisation of geographic information. The focus however is not on traditional paper maps, but on screen maps that are automatically generated from a geographical database. Object oriented modelling is used to design screen maps that are equipped with methods that automatically extracts information from a geographical database, generalises the information and displays it on a screen. The thesis consists of three parts: a theoreti...
Automatic program generation: future of software engineering
Robinson, J.H.
1979-01-01
At this moment software development is still more of an art than an engineering discipline. Each piece of software is lovingly engineered, nurtured, and presented to the world as a tribute to the writer's skill. When will this change. When will the craftsmanship be removed and the programs be turned out like so many automobiles from an assembly line. Sooner or later it will happen: economic necessities will demand it. With the advent of cheap microcomputers and ever more powerful supercomputers doubling capacity, much more software must be produced. The choices are to double the number of programers, double the efficiency of each programer, or find a way to produce the needed software automatically. Producing software automatically is the only logical choice. How will automatic programing come about. Some of the preliminary actions which need to be done and are being done are to encourage programer plagiarism of existing software through public library mechanisms, produce well understood packages such as compiler automatically, develop languages capable of producing software as output, and learn enough about the whole process of programing to be able to automate it. Clearly, the emphasis must not be on efficiency or size, since ever larger and faster hardware is coming.
ZONE: a finite element mesh generator. [In FORTRAN IV for CDC 7600
Burger, M. J.
1976-05-01
The ZONE computer program is a finite-element mesh generator which produces the nodes and element description of any two-dimensional geometry. The geometry is subdivided into a mesh of quadrilateral and triangular zones arranged sequentially in an ordered march through the geometry. The order of march can be chosen so that the minimum bandwidth is obtained. The node points are defined in terms of the x and y coordinates in a global rectangular coordinate system. The zones generated are quadrilaterals or triangles defined by four node points in a counterclockwise sequence. Node points defining the outside boundary are generated to describe pressure boundary conditions. The mesh that is generated can be used as input to any two-dimensional as well as any axisymmetrical structure program. The output from ZONE is essentially the input file to NAOS, HONDO, and other axisymmetric finite element programs. 14 figures. (RWR)
Mobility Models for Next Generation Wireless Networks Ad Hoc, Vehicular and Mesh Networks
Santi, Paolo
2012-01-01
Mobility Models for Next Generation Wireless Networks: Ad Hoc, Vehicular and Mesh Networks provides the reader with an overview of mobility modelling, encompassing both theoretical and practical aspects related to the challenging mobility modelling task. It also: Provides up-to-date coverage of mobility models for next generation wireless networksOffers an in-depth discussion of the most representative mobility models for major next generation wireless network application scenarios, including WLAN/mesh networks, vehicular networks, wireless sensor networks, and
Automatically Generating Game Tactics through Evolutionary Learning
Ponsen, Marc; Munoz-Avila, Hector; Spronck, Pieter; Aha, David W.
2006-01-01
The decision-making process of computer-controlled opponents in video games is called game AI. Adaptive game AI can improve the entertainment value of games by allowing computer-controlled opponents to ix weaknesses automatically in the game AI and to respond to changes in human-player tactics. Dynamic scripting is a reinforcement learning approach to adaptive game AI that learns, during gameplay, which game tactics an opponent should select to play effectively. In previous work, the tactics ...
Automatic Structure-Based Code Generation from Coloured Petri Nets
Kristensen, Lars Michael; Westergaard, Michael
2010-01-01
Automatic code generation based on Coloured Petri Net (CPN) models is challenging because CPNs allow for the construction of abstract models that intermix control flow and data processing, making translation into conventional programming constructs difficult. We introduce Process-Partitioned CPNs...... viability of our approach is demonstrated by applying it to automatically generate an Erlang implementation of the Dynamic MANET On-demand (DYMO) routing protocol specified by the Internet Engineering Task Force (IETF)....
Sharifi, Hamid; Larouche, Daniel
2015-09-01
The quality of cast metal products depends on the capacity of the semi-solid metal to sustain the stresses generated during the casting. Predicting the evolution of these stresses with accuracy in the solidification interval should be highly helpful to avoid the formation of defects like hot tearing. This task is however very difficult because of the heterogeneous nature of the material. In this paper, we propose to evaluate the mechanical behaviour of a metal during solidification using a mesh generation technique of the heterogeneous semi-solid material for a finite element analysis at the microscopic level. This task is done on a two-dimensional (2D) domain in which the granular structure of the solid phase is generated surrounded by an intergranular and interdendritc liquid phase. Some basic solid grains are first constructed and projected in the 2D domain with random orientations and scale factors. Depending on their orientation, the basic grains are combined to produce larger grains or separated by a liquid film. Different basic grain shapes can produce different granular structures of the mushy zone. As a result, using this automatic grain generation procedure, we can investigate the effect of grain shapes and sizes on the thermo-mechanical behaviour of the semi-solid material. The granular models are automatically converted to the finite element meshes. The solid grains and the liquid phase are meshed properly using quadrilateral elements. This method has been used to simulate the microstructure of a binary aluminium-copper alloy (Al-5.8 wt% Cu) when the fraction solid is 0.92. Using the finite element method and the Mie-Grüneisen equation of state for the liquid phase, the transient mechanical behaviour of the mushy zone under tensile loading has been investigated. The stress distribution and the bridges, which are formed during the tensile loading, have been detected.
有限元网格剖分与网格质量判定指标%Finite Element Mesh Generation and Decision Criteria of Mesh Quality
李海峰; 吴冀川; 刘建波; 梁宇兵
2012-01-01
讨论了网格剖分中的一些常见问题,阐述了网格剖分中应遵循的要求,介绍了近十多年来网格剖分方法的研究进展,回顾了网格剖分的各种算法,并比较了各种算法的优缺点。基于工程计算需求,提出了网格质量要求及判定指标,探讨了网格质量优化问题。同时,介绍了当前广泛使用的网格剖分前处理商业软件及其应用状况,并结合工作实际,给出了复杂模型网格剖分的具体实例。最后展望了网格剖分的发展趋势。%Some general problems in mesh generation were discussed,the demands of mesh generation were expounded,the mesh generation methods were introduced,the mesh generation algorithms in last ten years were retrospected and their advantages and disadvantages were compared.Based on the requirements of practical engineering calculation,the authors brought up the mesh quality demands and decision index,explored the mesh quality optimization,introduced the preprocessors and their applications of the commercial softwares,then gave out several practical examples of the mesh generation.At last,the trends of mesh generation were also presented.
Qiu-Yu Lu; Wei Hu; Le Zheng; Yong Min; Miao Li; Xiao-Ping Li; Wei-Chun Ge; Zhi-Ming Wang
2012-01-01
Automatic Generation Control (AGC) and Automatic Voltage Control (AVC) are key approaches to frequency and voltage regulation in power systems. However, based on the assumption of decoupling of active and reactive power control, the existing AGC and AVC systems work independently without any coordination. In this paper, a concept and method of hybrid control is introduced to set up an Integrated Coordinated Optimization Control (ICOC) system for AGC and AVC. Concerning the diversity of contro...
6th International Meshing Roundtable '97
White, D.
1997-09-01
The goal of the 6th International Meshing Roundtable is to bring together researchers and developers from industry, academia, and government labs in a stimulating, open environment for the exchange of technical information related to the meshing process. In the pas~ the Roundtable has enjoyed significant participation born each of these groups from a wide variety of countries. The Roundtable will consist of technical presentations from contributed papers and abstracts, two invited speakers, and two invited panels of experts discussing topics related to the development and use of automatic mesh generation tools. In addition, this year we will feature a "Bring Your Best Mesh" competition and poster session to encourage discussion and participation from a wide variety of mesh generation tool users. The schedule and evening social events are designed to provide numerous opportunities for informal dialog. A proceedings will be published by Sandia National Laboratories and distributed at the Roundtable. In addition, papers of exceptionally high quaIity will be submitted to a special issue of the International Journal of Computational Geometry and Applications. Papers and one page abstracts were sought that present original results on the meshing process. Potential topics include but are got limited to: Unstructured triangular and tetrahedral mesh generation Unstructured quadrilateral and hexahedral mesh generation Automated blocking and structured mesh generation Mixed element meshing Surface mesh generation Geometry decomposition and clean-up techniques Geometry modification techniques related to meshing Adaptive mesh refinement and mesh quality control Mesh visualization Special purpose meshing algorithms for particular applications Theoretical or novel ideas with practical potential Technical presentations from industrial researchers.
Automatic Test Case Generation of C Program Using CFG
Sangeeta Tanwer
2010-07-01
Full Text Available Software quality and assurance in a software company is the only way to gain the customer confidence by removing all possible errors. It can be done by automatic test case generation. Taking popularly C programs as tests object, this paper explores how to create CFG of a C program and generate automatic Test Cases. It explores the feasibility and nonfeasibility of path basis upon no. of iteration. First C is code converted to instrumented code. Then test cases are generated by using Symbolic Testing and random Testing. System is developed by using C#.net in Visual Studio 2008. In addition some future research directions are also explored.
INGEN, 2-D, 3-D Mesh Generator for Finite Elements Program
1 - Description of problem or function: INGEN is a general-purpose mesh generator for use in conjunction with two- and three-dimensional finite element programs. The basic components of INGEN are surface and three-dimensional region generators that use linear-blending interpolation formulae. These generators are based on an i, j, k index scheme, which is used to number nodal points, construct elements, and develop displacement and traction boundary conditions. 2 - Method of solution: The user of INGEN develops a mesh grading by first generating the boundary edges of the mesh with the desired spacing of nodal points using the line and circular-arc generators and then using surface and volume (three-dimensional region) generators, both of which preserve this spacing. The surface nodal-point generator preserves this spacing by using the nodal points as they are distributed along the boundary edges as the criteria for spacing the surface nodal points. Similarly, the volume nodal-point generator calculates the interior nodal points, using the surface nodal points as the criteria for spacing the interior nodal points. Both the surface and volume generators use linear-blending interpolation equations for calculating nodal point coordinates. 3 - Restrictions on the complexity of the problem: The origin cannot be used as the coordinates of a nodal point because the zero coordinates are a test used for nonexistent nodal points
Automatic Generation of Video Narratives from Shared UGC
Zsombori, V.; Frantzis, M.; Guimarães, R.L.; Ursu, M.; Cesar Garcia, P.S.; Kegel, I.; Craigie, R.; Bulterman, D.C.A.
2011-01-01
This paper introduces an evaluated approach to the automatic generation of video narratives from user generated content gathered in a shared repository. In the context of social events, end-users record video material with their personal cameras and upload the content to a common repository. Video n
Automatic generation of matter-of-opinion video documentaries
Bocconi, S.; Nack, F.-M.; Hardman, L.
2008-01-01
In this paper we describe a model for automatically generating video documentaries. This allows viewers to specify the subject and the point of view of the documentary to be generated. The domain is matter-of-opinion documentaries based on interviews. The model combines rhetorical presentation patte
Automatic generation of a neural network architecture using evolutionary computation
Vonk, E.; Jain, L.C.; Veelenturf, L.P.J.; Johnson, R.
1995-01-01
This paper reports the application of evolutionary computation in the automatic generation of a neural network architecture. It is a usual practice to use trial and error to find a suitable neural network architecture. This is not only time consuming but may not generate an optimal solution for a gi
Vox populi: a tool for automatically generating video documentaries
Bocconi, S.; Nack, Frank; Hardman, Hazel Lynda
2005-01-01
Vox Populi is a system that automatically generates video documentaries. Our application domain is video interviews about controversial topics. Via a Web interface the user selects one of the possible topics and a point of view she would like the generated sequence to present, and the engine selects and assembles video material from the repository to satisfy the user request.
DECROOS Koenraad; OHMS Carsten; Petrov, Roumen; Seefeldt, Marc; Verhaeghe, Frederik; Kestens, Leo
2013-01-01
A new method has been designed to automatically adapt the geometry of the fusion zone of a weld according to the temperature calculations when the thermal welding heat source parameters are known. In the material definition in a Finite Element code for welding stress calculations, the fusion zone material has different properties than the base material since, among others, the temperature at which the material is stress free is the melting temperature instead of room temperature. In this work...
Automated Tetrahedral Mesh Generation for CFD Analysis of Aircraft in Conceptual Design
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.
Transonic Airfoil Flow Simulation. Part I: Mesh Generation and Inviscid Method
Vladimir CARDOS
2010-06-01
Full Text Available A calculation method for the subsonic and transonic viscous flow over airfoil using thedisplacement surface concept is described. Part I presents a mesh generation method forcomputational grid and a finite volume method for the time-dependent Euler equations. The inviscidsolution is used for the inviscid-viscous coupling procedure presented in the Part II.
Mapping method for generating three-dimensional meshes: past and present
Two transformations are derived in this paper. One is a mapping of a unit square onto a surve and the other is a mapping of a unit cube onto a three-dimensional region. Two meshing computer programs are then discussed that use these mappings. The first is INGEN, which has been used to calculate three-dimensional meshes for approximately 15 years. This meshing program uses an index scheme to number boundaries, surfaces, and regions. With such an index scheme, it is possible to control nodal points, elements, and boundary conditions. The second is ESCHER, a meshing program now being developed. Two primary considerations governing development of ESCHER are that meshes graded using quadrilaterals are required and that edge-line geometry defined by Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) systems will be a major source of geometry definition. This program separates the processes of nodal-point connectivity generation, computation of nodal-point mapping space coordinates, and mapping of nodal points into model space
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.
A unified approach for a posteriori high-order curved mesh generation using solid mechanics
Poya, Roman; Sevilla, Ruben; Gil, Antonio J.
2016-06-01
The paper presents a unified approach for the a posteriori generation of arbitrary high-order curvilinear meshes via a solid mechanics analogy. The approach encompasses a variety of methodologies, ranging from the popular incremental linear elastic approach to very sophisticated non-linear elasticity. In addition, an intermediate consistent incrementally linearised approach is also presented and applied for the first time in this context. Utilising a consistent derivation from energy principles, a theoretical comparison of the various approaches is presented which enables a detailed discussion regarding the material characterisation (calibration) employed for the different solid mechanics formulations. Five independent quality measures are proposed and their relations with existing quality indicators, used in the context of a posteriori mesh generation, are discussed. Finally, a comprehensive range of numerical examples, both in two and three dimensions, including challenging geometries of interest to the solids, fluids and electromagnetics communities, are shown in order to illustrate and thoroughly compare the performance of the different methodologies. This comparison considers the influence of material parameters and number of load increments on the quality of the generated high-order mesh, overall computational cost and, crucially, the approximation properties of the resulting mesh when considering an isoparametric finite element formulation.
Kainmueller, Dagmar
2014-01-01
? Segmentation of anatomical structures in medical image data is an essential task in clinical practice. Dagmar Kainmueller introduces methods for accurate fully automatic segmentation of anatomical structures in 3D medical image data. The author's core methodological contribution is a novel deformation model that overcomes limitations of state-of-the-art Deformable Surface approaches, hence allowing for accurate segmentation of tip- and ridge-shaped features of anatomical structures. As for practical contributions, she proposes application-specific segmentation pipelines for a range of anatom
A set of computer codes for triangular six-node finite element mesh generation in fast reactor fuel assemblies (or their parts) is described as are directions for input data preparation and operator's actions. The generated meshes are utilized for velocity and temperature calculations. (author)
Hazer, D.; Schmidt, E.; Unterhinninghofen, R.; Richter, G. M.; Dillmann, R.
2009-08-01
Abnormal hemodynamics and biomechanics of blood flow and vessel wall conditions in the arteries may result in severe cardiovascular diseases. Cardiovascular diseases result from complex flow pattern and fatigue of the vessel wall and are prevalent causes leading to high mortality each year. Computational Fluid Dynamics (CFD), Computational Structure Mechanics (CSM) and Fluid Structure Interaction (FSI) have become efficient tools in modeling the individual hemodynamics and biomechanics as well as their interaction in the human arteries. The computations allow non-invasively simulating patient-specific physical parameters of the blood flow and the vessel wall needed for an efficient minimally invasive treatment. The numerical simulations are based on the Finite Element Method (FEM) and require exact and individual mesh models to be provided. In the present study, we developed a numerical tool to automatically generate complex patient-specific Finite Element (FE) mesh models from image-based geometries of healthy and diseased vessels. The mesh generation is optimized based on the integration of mesh control functions for curvature, boundary layers and mesh distribution inside the computational domain. The needed mesh parameters are acquired from a computational grid analysis which ensures mesh-independent and stable simulations. Further, the generated models include appropriate FE sets necessary for the definition of individual boundary conditions, required to solve the system of nonlinear partial differential equations governed by the fluid and solid domains. Based on the results, we have performed computational blood flow and vessel wall simulations in patient-specific aortic models providing a physical insight into the pathological vessel parameters. Automatic mesh generation with individual awareness in terms of geometry and conditions is a prerequisite for performing fast, accurate and realistic FEM-based computations of hemodynamics and biomechanics in the
MEMOPS: data modelling and automatic code generation.
Fogh, Rasmus H; Boucher, Wayne; Ionides, John M C; Vranken, Wim F; Stevens, Tim J; Laue, Ernest D
2010-01-01
In recent years the amount of biological data has exploded to the point where much useful information can only be extracted by complex computational analyses. Such analyses are greatly facilitated by metadata standards, both in terms of the ability to compare data originating from different sources, and in terms of exchanging data in standard forms, e.g. when running processes on a distributed computing infrastructure. However, standards thrive on stability whereas science tends to constantly move, with new methods being developed and old ones modified. Therefore maintaining both metadata standards, and all the code that is required to make them useful, is a non-trivial problem. Memops is a framework that uses an abstract definition of the metadata (described in UML) to generate internal data structures and subroutine libraries for data access (application programming interfaces--APIs--currently in Python, C and Java) and data storage (in XML files or databases). For the individual project these libraries obviate the need for writing code for input parsing, validity checking or output. Memops also ensures that the code is always internally consistent, massively reducing the need for code reorganisation. Across a scientific domain a Memops-supported data model makes it easier to support complex standards that can capture all the data produced in a scientific area, share them among all programs in a complex software pipeline, and carry them forward to deposition in an archive. The principles behind the Memops generation code will be presented, along with example applications in Nuclear Magnetic Resonance (NMR) spectroscopy and structural biology. PMID:20375445
Bucki, Marek; Payan, Yohan; 10.1016/j.media.2010.02.003
2010-01-01
Finite Element mesh generation remains an important issue for patient specific biomechanical modeling. While some techniques make automatic mesh generation possible, in most cases, manual mesh generation is preferred for better control over the sub-domain representation, element type, layout and refinement that it provides. Yet, this option is time consuming and not suited for intraoperative situations where model generation and computation time is critical. To overcome this problem we propose a fast and automatic mesh generation technique based on the elastic registration of a generic mesh to the specific target organ in conjunction with element regularity and quality correction. This Mesh-Match-and-Repair (MMRep) approach combines control over the mesh structure along with fast and robust meshing capabilities, even in situations where only partial organ geometry is available. The technique was successfully tested on a database of 5 pre-operatively acquired complete femora CT scans, 5 femoral heads partially...
ZONE - a finite element mesh generator. [2-D, for CDC 7600
Burger, M.J.
1980-03-12
The ZONE computer program is a finite element mesh generator that produces the nodes and element description of any two-dimensional geometry. The geometry is subdivided into a mesh of quadrilateral and triangular zones arranged sequentially in an ordered march through the geometry. The order of march can be chosen so that the minimum bandwidth is obtained. The node points are defined in terms of the x and y coordinates in a global rectangular coordinate system. The zones generated are quadrilaterals or triangles defined by four node points in a counterclockwise sequence. Node points defining the outside boundary are generated for slide lines and to describe pressure boundary conditions. The mesh that is generated can be used as input to any two dimensional as well as any axisymmetrical structure program. The following points are taken up: program concept and characteristics; regions; layers; meridians (offset, circular arc, ellipse); rays; common characterstics - rays and meridians, ZONE input description; output files; examples; and program availability. Also generated is the input to the program PLOT. 15 figures. (RWR)
Automatic Generation of Tests from Domain and Multimedia Ontologies
Papasalouros, Andreas; Kotis, Konstantinos; Kanaris, Konstantinos
2011-01-01
The aim of this article is to present an approach for generating tests in an automatic way. Although other methods have been already reported in the literature, the proposed approach is based on ontologies, representing both domain and multimedia knowledge. The article also reports on a prototype implementation of this approach, which…
Mppsocgen: A framework for automatic generation of mppsoc architecture
Kallel, Emna; Baklouti, Mouna; Abid, Mohamed
2012-01-01
Automatic code generation is a standard method in software engineering since it improves the code consistency and reduces the overall development time. In this context, this paper presents a design flow for automatic VHDL code generation of mppSoC (massively parallel processing System-on-Chip) configuration. Indeed, depending on the application requirements, a framework of Netbeans Platform Software Tool named MppSoCGEN was developed in order to accelerate the design process of complex mppSoC. Starting from an architecture parameters design, VHDL code will be automatically generated using parsing method. Configuration rules are proposed to have a correct and valid VHDL syntax configuration. Finally, an automatic generation of Processor Elements and network topologies models of mppSoC architecture will be done for Stratix II device family. Our framework improves its flexibility on Netbeans 5.5 version and centrino duo Core 2GHz with 22 Kbytes and 3 seconds average runtime. Experimental results for reduction al...
A quick scan on possibilities for automatic metadata generation
Benneker, Frank
2006-01-01
The Quick Scan is a report on research into useable solutions for automatic generation of metadata or parts of metadata. The aim of this study is to explore possibilities for facilitating the process of attaching metadata to learning objects. This document is aimed at developers of digital learning
Algorithm for automatic generating motion trajectories of plant maintenance robot
The algorithm for automatic generating motion trajectories of robot manipulator is proposed as a new method to operate plant maintenance robots. This algorithm consists of two procedures, motion trajectories of the end effecter and the posture of robot manipulator. Motion trajectories of the end effecter are generated by using a concept of repulsive force vector field. The motion trajectories model which consists of many virtual springs and mass points are changed their form using the repulsive force from obstacles. Then, a posture of robot manipulator is also automatically generated with the same concept. By using this algorithm, an experiment of generating motion with the 7 degrees of freedom (DOF) manipulator was carried out. As a result, it was confirmed that the proposed method realizes obstacle avoidance during task motion. We are planning to apply this system to nuclear power plants. This system can realize shortening of preparation and operation periods for maintenance work in the nuclear reactor. (author)
Video2GIF: Automatic Generation of Animated GIFs from Video
Gygli, Michael; Song, Yale; Cao, Liangliang
2016-01-01
We introduce the novel problem of automatically generating animated GIFs from video. GIFs are short looping video with no sound, and a perfect combination between image and video that really capture our attention. GIFs tell a story, express emotion, turn events into humorous moments, and are the new wave of photojournalism. We pose the question: Can we automate the entirely manual and elaborate process of GIF creation by leveraging the plethora of user generated GIF content? We propose a Robu...
AN APPROACH TO GENERATE TEST CASES AUTOMATICALLY USING GENETIC ALGORITHM
Deepika Sharma*, Dr. Sanjay Tyagi
2016-01-01
Software testing is a very crucial part among all phases of software life cycle model in software engineering, which leads to better software quality and reliability. The main issue of software testing is the incompleteness of testing due to the vast amount of possible test cases which increase the effort and cost of the software. So generating adequate test cases will help to reduce the effort and cost of the software. The purpose of this research paper is to automatically generate test case...
Extending a CAD-Based Cartesian Mesh Generator for the Lattice Boltzmann Method
Cantrell, J Nathan [ORNL; Inclan, Eric J [ORNL; Joshi, Abhijit S [ORNL; Popov, Emilian L [ORNL; Jain, Prashant K [ORNL
2012-01-01
This paper describes the development of a custom preprocessor for the PaRAllel Thermal Hydraulics simulations using Advanced Mesoscopic methods (PRATHAM) code based on an open-source mesh generator, CartGen [1]. PRATHAM is a three-dimensional (3D) lattice Boltzmann method (LBM) based parallel flow simulation software currently under development at the Oak Ridge National Laboratory. The LBM algorithm in PRATHAM requires a uniform, coordinate system-aligned, non-body-fitted structured mesh for its computational domain. CartGen [1], which is a GNU-licensed open source code, already comes with some of the above needed functionalities. However, it needs to be further extended to fully support the LBM specific preprocessing requirements. Therefore, CartGen is being modified to (i) be compiler independent while converting a neutral-format STL (Stereolithography) CAD geometry to a uniform structured Cartesian mesh, (ii) provide a mechanism for PRATHAM to import the mesh and identify the fluid/solid domains, and (iii) provide a mechanism to visually identify and tag the domain boundaries on which to apply different boundary conditions.
Algebraic mesh generation for large scale viscous-compressible aerodynamic simulation
Viscous-compressible aerodynamic simulation is the numerical solution of the compressible Navier-Stokes equations and associated boundary conditions. Boundary-fitted coordinate systems are well suited for the application of finite difference techniques to the Navier-Stokes equations. An algebraic approach to boundary-fitted coordinate systems is one where an explicit functional relation describes a mesh on which a solution is obtained. This approach has the advantage of rapid-precise mesh control. The basic mathematical structure of three algebraic mesh generation techniques is described. They are transfinite interpolation, the multi-surface method, and the two-boundary technique. The Navier-Stokes equations are transformed to a computational coordinate system where boundary-fitted coordinates can be applied. Large-scale computation implies that there is a large number of mesh points in the coordinate system. Computation of viscous compressible flow using boundary-fitted coordinate systems and the application of this computational philosophy on a vector computer are presented
Mauro Massayoshi Sakamoto; José Roberto Cardoso; José Marcio Machado
2008-01-01
In this work, a software package based on the Delaunay´s algorithm is described. The main feature of this package is the capability in applying discretization in geometric domains of teeth taking into account their complex inner structures and the materials with different hardness. Usually, the mesh generators reported in literature treat molars and other teeth by using simplified geometric models, or even considering the teeth as homogeneous structures.
Mauro Massayoshi Sakamoto
2008-01-01
Full Text Available In this work, a software package based on the Delaunay´s algorithm is described. The main feature of this package is the capability in applying discretization in geometric domains of teeth taking into account their complex inner structures and the materials with different hardness. Usually, the mesh generators reported in literature treat molars and other teeth by using simplified geometric models, or even considering the teeth as homogeneous structures.
AUTOCASK (AUTOmatic Generation of 3-D CASK models) is a microcomputer-based system of computer programs and databases developed at the Lawrence Livermore National Laboratory (LLNL) for the structural analysis of shipping casks for radioactive material. Model specification is performed on the microcomputer, and the analyses are performed on an engineering workstation or mainframe computer. AUTOCASK is based on 80386/80486 compatible microcomputers. The system is composed of a series of menus, input programs, display programs, a mesh generation program, and archive programs. All data is entered through fill-in-the-blank input screens that contain descriptive data requests
Lorié, William A.
2013-01-01
A reverse engineering approach to automatic item generation (AIG) was applied to a figure-based publicly released test item from the Organisation for Economic Cooperation and Development (OECD) Programme for International Student Assessment (PISA) mathematical literacy cognitive instrument as part of a proof of concept. The author created an item…
Automatic control system generation for robot design validation
Bacon, James A. (Inventor); English, James D. (Inventor)
2012-01-01
The specification and drawings present a new method, system and software product for and apparatus for generating a robotic validation system for a robot design. The robotic validation system for the robot design of a robotic system is automatically generated by converting a robot design into a generic robotic description using a predetermined format, then generating a control system from the generic robotic description and finally updating robot design parameters of the robotic system with an analysis tool using both the generic robot description and the control system.
Automatic generation of neural network architecture using evolutionary computation
Vonk, E
1997-01-01
This book describes the application of evolutionary computation in the automatic generation of a neural network architecture. The architecture has a significant influence on the performance of the neural network. It is the usual practice to use trial and error to find a suitable neural network architecture for a given problem. The process of trial and error is not only time-consuming but may not generate an optimal network. The use of evolutionary computation is a step towards automation in neural network architecture generation.An overview of the field of evolutionary computation is presented
Automated Generation of Finite-Element Meshes for Aircraft Conceptual Design
Li, Wu; Robinson, Jay
2016-01-01
This paper presents a novel approach for automated generation of fully connected finite-element meshes for all internal structural components and skins of a given wing-body geometry model, controlled by a few conceptual-level structural layout parameters. Internal structural components include spars, ribs, frames, and bulkheads. Structural layout parameters include spar/rib locations in wing chordwise/spanwise direction and frame/bulkhead locations in longitudinal direction. A simple shell thickness optimization problem with two load conditions is used to verify versatility and robustness of the automated meshing process. The automation process is implemented in ModelCenter starting from an OpenVSP geometry and ending with a NASTRAN 200 solution. One subsonic configuration and one supersonic configuration are used for numerical verification. Two different structural layouts are constructed for each configuration and five finite-element meshes of different sizes are generated for each layout. The paper includes various comparisons of solutions of 20 thickness optimization problems, as well as discussions on how the optimal solutions are affected by the stress constraint bound and the initial guess of design variables.
Optimum siting and sizing of a large distributed generator in a mesh connected system
Elnashar, Mohab M.; El Shatshat, Ramadan; Salama, Magdy M.A. [Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario (Canada)
2010-06-15
This paper proposes a new approach to optimally determine the appropriate size and location of the distributed generator (DG) in a large mesh connected system. This paper presents a visual optimization approach in which the planner plays an important role in determining the optimal siting and sizing of the DG through the choice of the appropriate weight factors of the parameters included in the optimization technique according to the system deficiencies. Losses, voltage profile and short circuit level are used in the algorithm to determine the optimum sizes and locations of the DG. The short circuit level parameter is introduced to represent the protective device requirements in the selection of the size and location of the DG. The proposed technique has been tested on the IEEE 24 - bus mesh connected test system. The obtained results showed clearly that the optimal size and location can be simply determined through the proposed approach. (author)
An automatic control system for a power-generating unit
Itelman, U.R.; Mankin, M.N.; Mikhailova, I.V.
1979-02-05
There exists an automatic control system for a power-generating unit, which contains a load regulator for the turbine, which is connected to the output of the actuator valve servo motor together with the slide valve of the regulator measuring channel, a boiler productivity regulator and a frequency-compensation unit for controlling the input power; the output from this unit is connected to the input to the turbine load regulator and the boiler productivity regulator. In this automatic control system, the compensation unit is manufactured in the form of a frequency deviation sensor connected to the voltage transformer of the generator--it is a complex electronic and conversion component. In order to simplify this design of the compensation unit, it is manufactured as a motion sensor, which is mechanically connected to the slide valve. This connection is made through the slide box of the valve or through the valve position rod.
Automatic Generation of Thematically Focused Information Portals from Web Data
Sizov, Sergej
2005-01-01
Finding the desired information on the Web is often a hard and time-consuming task. This thesis presents the methodology of automatic generation of thematically focused portals from Web data. The key component of the proposed Web retrieval framework is the thematically focused Web crawler that is interested only in a specific, typically small, set of topics. The focused crawler uses classification methods for filtering of fetched documents and identifying most likely relevant Web source...
MadEvent: automatic event generation with MadGraph
We present a new multi-channel integration method and its implementation in the multi-purpose event generator MadEvent, which is based on MadGraph. Given a process, MadGraph automatically identifies all the relevant subprocesses, generates both the amplitudes and the mappings needed for an efficient integration over the phase space, and passes them to MadEvent. As a result, a process-specific, stand-alone code is produced that allows the user to calculate cross sections and produce unweighted events in a standard output format. Several examples are given for processes that are relevant for physics studies at present and forthcoming colliders. (author)
Progressive Concept Evaluation Method for Automatically Generated Concept Variants
Woldemichael Dereje Engida
2014-07-01
Full Text Available Conceptual design is one of the most critical and important phases of design process with least computer support system. Conceptual design support tool (CDST is a conceptual design support system developed to automatically generate concepts for each subfunction in functional structure. The automated concept generation process results in large number of concept variants which require a thorough evaluation process to select the best design. To address this, a progressive concept evaluation technique consisting of absolute comparison, concept screening and weighted decision matrix using analytical hierarchy process (AHP is proposed to eliminate infeasible concepts at each stage. The software implementation of the proposed method is demonstrated.
Impulse Wave Generation: Comparison of Free Granular with Mesh-Packed Slides
Frederic M. Evers
2015-03-01
Full Text Available Slides generating impulse waves are currently generated using either block models or free granular material impacting a water body. These procedures were mainly developed to study plane impulse waves, i.e., wave generation in a rectangular channel. The current VAW, ETH Zurich, research is directed to the spatial impulse wave features, i.e., waves propagating in a wave basin. The two wave generation mechanisms mentioned above complicate this process for various reasons, including experimental handling, collection of slide material in the wave basin, poor representation of prototype conditions for the block model, and excessive temporal duration for free granular slides. Impulse waves originating from slides with free granular material and mesh-packed slides are compared in this paper. Detailed test series are presented, so that the resulting main wave features can be compared. The results highlight whether the simplified procedure involving mesh-packed slides really applies in future research, and specify advantages in terms of impulse wave experimentation.
Sarkis, C.; Silva, L.; Gandin, Ch-A.; Plapp, M.
2016-03-01
Dendritic growth is computed with automatic adaptation of an anisotropic and unstructured finite element mesh. The energy conservation equation is formulated for solid and liquid phases considering an interface balance that includes the Gibbs-Thomson effect. An equation for a diffuse interface is also developed by considering a phase field function with constant negative value in the liquid and constant positive value in the solid. Unknowns are the phase field function and a dimensionless temperature, as proposed by [1]. Linear finite element interpolation is used for both variables, and discretization stabilization techniques ensure convergence towards a correct non-oscillating solution. In order to perform quantitative computations of dendritic growth on a large domain, two additional numerical ingredients are necessary: automatic anisotropic unstructured adaptive meshing [2,[3] and parallel implementations [4], both made available with the numerical platform used (CimLib) based on C++ developments. Mesh adaptation is found to greatly reduce the number of degrees of freedom. Results of phase field simulations for dendritic solidification of a pure material in two and three dimensions are shown and compared with reference work [1]. Discussion on algorithm details and the CPU time will be outlined.
Automatic generation of executable communication specifications from parallel applications
Pakin, Scott [Los Alamos National Laboratory; Wu, Xing [NCSU; Mueller, Frank [NCSU
2011-01-19
Portable parallel benchmarks are widely used and highly effective for (a) the evaluation, analysis and procurement of high-performance computing (HPC) systems and (b) quantifying the potential benefits of porting applications for new hardware platforms. Yet, past techniques to synthetically parameterized hand-coded HPC benchmarks prove insufficient for today's rapidly-evolving scientific codes particularly when subject to multi-scale science modeling or when utilizing domain-specific libraries. To address these problems, this work contributes novel methods to automatically generate highly portable and customizable communication benchmarks from HPC applications. We utilize ScalaTrace, a lossless, yet scalable, parallel application tracing framework to collect selected aspects of the run-time behavior of HPC applications, including communication operations and execution time, while abstracting away the details of the computation proper. We subsequently generate benchmarks with identical run-time behavior from the collected traces. A unique feature of our approach is that we generate benchmarks in CONCEPTUAL, a domain-specific language that enables the expression of sophisticated communication patterns using a rich and easily understandable grammar yet compiles to ordinary C + MPI. Experimental results demonstrate that the generated benchmarks are able to preserve the run-time behavior - including both the communication pattern and the execution time - of the original applications. Such automated benchmark generation is particularly valuable for proprietary, export-controlled, or classified application codes: when supplied to a third party. Our auto-generated benchmarks ensure performance fidelity but without the risks associated with releasing the original code. This ability to automatically generate performance-accurate benchmarks from parallel applications is novel and without any precedence, to our knowledge.
Visual definition of procedures for automatic virtual scene generation
Lucanin, Drazen
2012-01-01
With more and more digital media, especially in the field of virtual reality where detailed and convincing scenes are much required, procedural scene generation is a big helping tool for artists. A problem is that defining scene descriptions through these procedures usually requires a knowledge in formal language grammars, programming theory and manually editing textual files using a strict syntax, making it less intuitive to use. Luckily, graphical user interfaces has made a lot of tasks on computers easier to perform and out of the belief that creating computer programs can also be one of them, visual programming languages (VPLs) have emerged. The goal in VPLs is to shift more work from the programmer to the integrated development environment (IDE), making programming an user-friendlier task. In this thesis, an approach of using a VPL for defining procedures that automatically generate virtual scenes is presented. The methods required to build a VPL are presented, including a novel method of generating read...
Automatic generation of alignments for 3D QSAR analyses.
Jewell, N E; Turner, D B; Willett, P; Sexton, G J
2001-01-01
Many 3D QSAR methods require the alignment of the molecules in a dataset, which can require a fair amount of manual effort in deciding upon a rational basis for the superposition. This paper describes the use of FBSS, a program for field-based similarity searching in chemical databases, for generating such alignments automatically. The CoMFA and CoMSIA experiments with several literature datasets show that the QSAR models resulting from the FBSS alignments are broadly comparable in predictive performance with the models resulting from manual alignments. PMID:11774998
Automatic generation of alignments for 3D QSAR analyses
Jewell, N.E.; D.B. Turner; Willett, P.; Sexton, G.J.
2001-01-01
Many 3D QSAR methods require the alignment of the molecules in a dataset, which can require a fair amount of manual effort in deciding upon a rational basis for the superposition. This paper describes the use of FBSS, a pro-ram for field-based similarity searching in chemical databases, for generating such alignments automatically. The CoMFA and CoMSIA experiments with several literature datasets show that the QSAR models resulting from the FBSS alignments are broadly comparable in predictive...
Automatic generation of application specific FPGA multicore accelerators
Hindborg, Andreas Erik; Schleuniger, Pascal; Jensen, Nicklas Bo;
2014-01-01
. In this paper we propose a tool flow, which automatically generates highly optimized hardware multicore systems based on parameters. Profiling feedback is used to adjust these parameters to improve performance and lower the power consumption. For an image processing application we show that our tools are able......High performance computing systems make increasing use of hardware accelerators to improve performance and power properties. For large high-performance FPGAs to be successfully integrated in such computing systems, methods to raise the abstraction level of FPGA programming are required...
Automatic Generation of 3D Building Models with Multiple Roofs
Kenichi Sugihara; Yoshitugu Hayashi
2008-01-01
Based on building footprints (building polygons) on digital maps, we are proposing the GIS and CG integrated system that automatically generates 3D building models with multiple roofs. Most building polygons' edges meet at right angles (orthogonal polygon). The integrated system partitions orthogonal building polygons into a set of rectangles and places rectangular roofs and box-shaped building bodies on these rectangles. In order to partition an orthogonal polygon, we proposed a useful polygon expression in deciding from which vertex a dividing line is drawn. In this paper, we propose a new scheme for partitioning building polygons and show the process of creating 3D roof models.
Raut, Samarth S; Liu, Peng; Finol, Ender A
2015-07-16
In this work, we present a computationally efficient image-derived volume mesh generation approach for vasculatures that implements spatially varying patient-specific wall thickness with a novel inward extrusion of the wall surface mesh. Multi-domain vascular meshes with arbitrary numbers, locations, and patterns of both iliac bifurcations and thrombi can be obtained without the need to specify features or landmark points as input. In addition, the mesh output is coordinate-frame independent and independent of the image grid resolution with high dimensional accuracy and mesh quality, devoid of errors typically found in off-the-shelf image-based model generation workflows. The absence of deformable template models or Cartesian grid-based methods enables the present approach to be sufficiently robust to handle aneurysmatic geometries with highly irregular shapes, arterial branches nearly parallel to the image plane, and variable wall thickness. The assessment of the methodology was based on i) estimation of the surface reconstruction accuracy, ii) validation of the output mesh using an aneurysm phantom, and iii) benchmarking the volume mesh quality against other frameworks. For the phantom image dataset (pixel size 0.105 mm; slice spacing 0.7 mm; and mean wall thickness 1.401±0.120 mm), the average wall thickness in the mesh was 1.459±0.123 mm. The absolute error in average wall thickness was 0.060±0.036 mm, or about 8.6% of the largest image grid spacing (0.7 mm) and 4.36% of the actual mean wall thickness. Mesh quality metrics and the ability to reproduce regional variations of wall thickness were found superior to similar alternative frameworks. PMID:25976018
Pavarino, E.; Neves, L. A.; Machado, J. M.; de Godoy, M. F.; Y. Shiyou; Momente, J. C.; Zafalon, G. F. D.; A.R. Pinto; C. R. Valêncio
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 preproc...
Semi-Automatic Construction of the Chinese-English MeSH Using Web-Based Term Translation Method
Lu, Wen-Hsiang; Lin, Shih-Jui; Chan, Yi-Che; Chen, Kuan-Hsi
2005-01-01
Due to language barrier, non-English users are unable to retrieve the most updated medical information from the U.S. authoritative medical websites, such as PubMed and MedlinePlus. A few cross-language medical information retrieval (CLMIR) systems have been utilizing MeSH (Medical Subject Heading) with multilingual thesaurus to bridge the gap. Unfortunately, MeSH has yet not been translated into traditional Chinese currently.
The Geometry of r-adaptive meshes generated using Optimal Transport Methods
C. J. Budd; Russell, R. D.; Walsh, E.
2014-01-01
The principles of mesh equidistribution and alignment play a fundamental role in the design of adaptive methods, and a metric tensor M and mesh metric are useful theoretical tools for understanding a methods level of mesh alignment, or anisotropy. We consider a mesh redistribution method based on the Monge-Ampere equation, which combines equidistribution of a given scalar density function with optimal transport. It does not involve explicit use of a metric tensor M, although such a tensor mus...
Node-based parallel mesh generation and finite element solver for high speed compressible flows
A node-based parallel mesh generation and finite element procedure for high speed compressible flows is presented. In general, the numerical analysis of flows with shock waves requires very fine computational grids and consumes a lot of computing time. For such large amounts of calculations, parallel computing is very effective. However, a lot of parallel techniques for CFD focus strictly on the solution of the system of equations, while the mesh generation process is not parallelized in many cases. In the present work, we attempt seamless parallel computing involving pre-processing and main-processing for compressible flows. The finite elements are generated in the local area around each node and the finite element assembly operations are carried out node-by-node. In this method, both pre-processing and main-processing are parallelized by means of the nodal identification number. Load balancing is achieved by simply allocating equal number of nodes to each processor. Furthermore, the amount of the communication among processors is minimized by reordering the nodal identification number using the parallel graph partitioning library, ParMETIS. As for the numerical scheme for compressible Euler equations, the two-step Taylor-Galerkin method is employed. In order to remove the numerical instability, artificial viscosity based on the Lapidus model is applied. The concept of an element in the usual FEM is represented by a data structure of the connectivity between a central node and associated satellite nodes. The communication among different processors is required if and only if associated satellite nodes exist in other processors. The present method is implemented on distributed memory systems such as a PC cluster and a commercial massively paralleled computer. The performance of the method is illustrated by computing of supersonic flows over a forward facing step. These examples show that crisp shock waves are effectively computed on multiple processors. The total
Qiu-Yu Lu
2012-09-01
Full Text Available Automatic Generation Control (AGC and Automatic Voltage Control (AVC are key approaches to frequency and voltage regulation in power systems. However, based on the assumption of decoupling of active and reactive power control, the existing AGC and AVC systems work independently without any coordination. In this paper, a concept and method of hybrid control is introduced to set up an Integrated Coordinated Optimization Control (ICOC system for AGC and AVC. Concerning the diversity of control devices and the characteristics of discrete control interaction with a continuously operating power system, the ICOC system is designed in a hierarchical structure and driven by security, quality and economic events, consequently reducing optimization complexity and realizing multi-target quasi-optimization. In addition, an innovative model of Loss Minimization Control (LMC taking into consideration active and reactive power regulation is proposed to achieve a substantial reduction in network losses and a cross iterative method for AGC and AVC instructions is also presented to decrease negative interference between control systems. The ICOC system has already been put into practice in some provincial regional power grids in China. Open-looping operation tests have proved the validity of the presented control strategies.
Optical breast shape capture and finite-element mesh generation for electrical impedance tomography
X-ray mammography is the standard for breast cancer screening. The development of alternative imaging modalities is desirable because mammograms expose patients to ionizing radiation. Electrical impedance tomography (EIT) may be used to determine tissue conductivity, a property which is an indicator of cancer presence. EIT is also a low-cost imaging solution and does not involve ionizing radiation. In breast EIT, impedance measurements are made using electrodes placed on the surface of the patient's breast. The complex conductivity of the volume of the breast is estimated by a reconstruction algorithm. EIT reconstruction is a severely ill-posed inverse problem. As a result, noisy instrumentation and incorrect modelling of the electrodes and domain shape produce significant image artefacts. In this paper, we propose a method that has the potential to reduce these errors by accurately modelling the patient breast shape. A 3D hand-held optical scanner is used to acquire the breast geometry and electrode positions. We develop methods for processing the data from the scanner and producing volume meshes accurately matching the breast surface and electrode locations, which can be used for image reconstruction. We demonstrate this method for a plaster breast phantom and a human subject. Using this approach will allow patient-specific finite-element meshes to be generated which has the potential to improve the clinical value of EIT for breast cancer diagnosis
Automatic Tamil lyric generation based on ontological interpretation for semantics
Rajeswari Sridhar; D Jalin Gladis; Kameswaran Ganga; G Dhivya Prabha
2014-02-01
This system proposes an -gram based approach to automatic Tamil lyric generation, by the ontological semantic interpretation of the input scene. The approach is based on identifying the semantics conveyed in the scenario, thereby making the system understand the situation and generate lyrics accordingly. The heart of the system includes the ontological interpretation of the scenario, and the selection of the appropriate tri-grams for generating the lyrics. To fulfill this, we have designed a new ontology with weighted edges, where the edges correspond to a set of sentences, which indicate a relationship, and are represented as a tri-gram. Once the appropriate tri-grams are selected, the root words from these tri-grams are sent to the morphological generator, to form words in their packed form. These words are then assembled to form the final lyrics. Parameters of poetry like rhyme, alliteration, simile, vocative words, etc., are also taken care of by the system. Using this approach, we achieved an average accuracy of 77.3% with respect to the exact semantic details being conveyed in the generated lyrics.
AUTO-LAY: automatic layout generation for procedure flow diagrams
Nuclear Power Plant Procedures can be seen from essentially two viewpoints: the process and the information management. From the first point of view, it is important to supply the knowledge apt to solve problems connected with the control of the process, from the second one the focus of attention is on the knowledge representation, its structure, elicitation and maintenance, formal quality assurance. These two aspects of procedure representation can be considered and solved separately. In particular, methodological, formal and management issues require long and tedious activities, that in most cases constitute a great barrier for procedures development and upgrade. To solve these problems, Ansaldo is developing DIAM, a wide integrated tool for procedure management to support in procedure writing, updating, usage and documentation. One of the most challenging features of DIAM is AUTO-LAY, a CASE sub-tool that, in a complete automatical way, structures parts or complete flow diagrams. This is a feature that is partially present in some other CASE products, that, anyway, do not allow complex graph handling and isomorphism between video and paper representation AUTO-LAY has the unique prerogative to draw graphs of any complexity, to section them in pages, and to automatically compose a document. This has been recognized in the literature as the most important second-generation CASE improvement. (author). 5 refs., 9 figs
Ricard, L.
2005-12-15
The high level geo-statistic description of the subsurface are often far too detailed for use in routine flow simulators. To make flow simulations tractable, the number of grid blocks has to be reduced: an approximation, still relevant with flow description, is necessary. In this work, we place the emphasis on the scaling procedure from the fine scale model to the multi-scale reservoir model. Two main problems appear: Near wells, faults and channels, the volume of flexible cells may be less than fine ones, so we need to solve a down-scaling problem; Far from these regions, the volume of cells are bigger than fine ones so we need to solve an up-scaling problem. In this work, research has been done on each of these three areas: down-scaling, up-scaling and fluid flow simulation. For each of these subjects, a review, some news improvements and comparative study are proposed. The proposed down-scaling method is build to be compatible with existing data integration methods. The comparative study shows that empirical methods are not enough accurate to solve the problem. Concerning the up-scaling step, the proposed approach is based on an existing method: the perturbed boundary conditions. An extension to unstructured mesh is developed for the inter-cell permeability tensor. The comparative study shows that numerical methods are not always as accurate as expected and the empirical model can be sufficient in lot of cases. A new approach to single-phase fluid flow simulation is developed. This approach can handle with full tensorial permeability fields with source or sink terms.(author)
Towards Automatic Personalized Content Generation for Platform Games
Shaker, Noor; Yannakakis, Georgios N.; Togelius, Julian
2010-01-01
In this paper, we show that personalized levels can be automatically generated for platform games. We build on previous work, where models were derived that predicted player experience based on features of level design and on playing styles. These models are constructed using preference learning......, based on questionnaires administered to players after playing different levels. The contributions of the current paper are (1) more accurate models based on a much larger data set; (2) a mechanism for adapting level design parameters to given players and playing style; (3) evaluation of this adaptation...... mechanism using both algorithmic and human players. The results indicate that the adaptation mechanism effectively optimizes level design parameters for particular players....
Hybrid Generative/Discriminative Learning for Automatic Image Annotation
Yang, Shuang Hong; Zha, Hongyuan
2012-01-01
Automatic image annotation (AIA) raises tremendous challenges to machine learning as it requires modeling of data that are both ambiguous in input and output, e.g., images containing multiple objects and labeled with multiple semantic tags. Even more challenging is that the number of candidate tags is usually huge (as large as the vocabulary size) yet each image is only related to a few of them. This paper presents a hybrid generative-discriminative classifier to simultaneously address the extreme data-ambiguity and overfitting-vulnerability issues in tasks such as AIA. Particularly: (1) an Exponential-Multinomial Mixture (EMM) model is established to capture both the input and output ambiguity and in the meanwhile to encourage prediction sparsity; and (2) the prediction ability of the EMM model is explicitly maximized through discriminative learning that integrates variational inference of graphical models and the pairwise formulation of ordinal regression. Experiments show that our approach achieves both su...
Automatic Generation of Symbolic Model for Parameterized Synchronous Systems
Wei-Wen Xu
2004-01-01
With the purpose of making the verification of parameterized system more general and easier, in this paper, a new and intuitive language PSL (Parameterized-system Specification Language) is proposed to specify a class of parameterized synchronous systems. From a PSL script, an automatic method is proposed to generate a constraint-based symbolic model. The model can concisely symbolically represent the collections of global states by counting the number of processes in a given state. Moreover, a theorem has been proved that there is a simulation relation between the original system and its symbolic model. Since the abstract and symbolic techniques are exploited in the symbolic model, state-explosion problem in traditional verification methods is efficiently avoided. Based on the proposed symbolic model, a reachability analysis procedure is implemented using ANSI C++ on UNIX platform. Thus, a complete tool for verifying the parameterized synchronous systems is obtained and tested for some cases. The experimental results show that the method is satisfactory.
Adaptive neuro-fuzzy inference system based automatic generation control
Hosseini, S.H.; Etemadi, A.H. [Department of Electrical Engineering, Sharif University of Technology, Tehran (Iran)
2008-07-15
Fixed gain controllers for automatic generation control are designed at nominal operating conditions and fail to provide best control performance over a wide range of operating conditions. So, to keep system performance near its optimum, it is desirable to track the operating conditions and use updated parameters to compute control gains. A control scheme based on artificial neuro-fuzzy inference system (ANFIS), which is trained by the results of off-line studies obtained using particle swarm optimization, is proposed in this paper to optimize and update control gains in real-time according to load variations. Also, frequency relaxation is implemented using ANFIS. The efficiency of the proposed method is demonstrated via simulations. Compliance of the proposed method with NERC control performance standard is verified. (author)
Automatic Generation of OWL Ontology from XML Data Source
Yahia, Nora; Ahmed, AbdelWahab
2012-01-01
The eXtensible Markup Language (XML) can be used as data exchange format in different domains. It allows different parties to exchange data by providing common understanding of the basic concepts in the domain. XML covers the syntactic level, but lacks support for reasoning. Ontology can provide a semantic representation of domain knowledge which supports efficient reasoning and expressive power. One of the most popular ontology languages is the Web Ontology Language (OWL). It can represent domain knowledge using classes, properties, axioms and instances for the use in a distributed environment such as the World Wide Web. This paper presents a new method for automatic generation of OWL ontology from XML data sources.
Jou, W.-H.
1982-01-01
An attempt is made to develop a three-dimensional, finite volume computational code for highly swept, twisted, small aspect ratio propeller blades with supersonic tip speeds, in a way that accounts for cascade effects, hub-induced flow, and nonlinear transonic effects. Attention is presently given to the generation of a computational mesh for such a complex propeller configuration, with the aim of sharing developmental process experience. The problem treated is unique, in that blade chord, blade length, hub length and blade-to-blade distance represent several characteristic length scales among which there is considerable disparity. An ad hoc mesh-generation scheme is accordingly developed.
Provenance-Powered Automatic Workflow Generation and Composition
Zhang, J.; Lee, S.; Pan, L.; Lee, T. J.
2015-12-01
In recent years, scientists have learned how to codify tools into reusable software modules that can be chained into multi-step executable workflows. Existing scientific workflow tools, created by computer scientists, require domain scientists to meticulously design their multi-step experiments before analyzing data. However, this is oftentimes contradictory to a domain scientist's daily routine of conducting research and exploration. We hope to resolve this dispute. Imagine this: An Earth scientist starts her day applying NASA Jet Propulsion Laboratory (JPL) published climate data processing algorithms over ARGO deep ocean temperature and AMSRE sea surface temperature datasets. Throughout the day, she tunes the algorithm parameters to study various aspects of the data. Suddenly, she notices some interesting results. She then turns to a computer scientist and asks, "can you reproduce my results?" By tracking and reverse engineering her activities, the computer scientist creates a workflow. The Earth scientist can now rerun the workflow to validate her findings, modify the workflow to discover further variations, or publish the workflow to share the knowledge. In this way, we aim to revolutionize computer-supported Earth science. We have developed a prototyping system to realize the aforementioned vision, in the context of service-oriented science. We have studied how Earth scientists conduct service-oriented data analytics research in their daily work, developed a provenance model to record their activities, and developed a technology to automatically generate workflow starting from user behavior and adaptability and reuse of these workflows for replicating/improving scientific studies. A data-centric repository infrastructure is established to catch richer provenance to further facilitate collaboration in the science community. We have also established a Petri nets-based verification instrument for provenance-based automatic workflow generation and recommendation.
Intelligent control schemes applied to Automatic Generation Control
Dingguo Chen
2016-04-01
Full Text Available Integrating ever increasing amount of renewable generating resources to interconnected power systems has created new challenges to the safety and reliability of today‟s power grids and posed new questions to be answered in the power system modeling, analysis and control. Automatic Generation Control (AGC must be extended to be able to accommodate the control of renewable generating assets. In addition, AGC is mandated to operate in accordance with the NERC‟s Control Performance Standard (CPS criteria, which represent a greater flexibility in relaxing the control of generating resources and yet assuring the stability and reliability of interconnected power systems when each balancing authority operates in full compliance. Enhancements in several aspects to the traditional AGC must be made in order to meet the aforementioned challenges. It is the intention of this paper to provide a systematic, mathematical formulation for AGC as a first attempt in the context of meeting the NERC CPS requirements and integrating renewable generating assets, which has not been seen reported in the literature to the best knowledge of the authors. Furthermore, this paper proposes neural network based predictive control schemes for AGC. The proposed controller is capable of handling complicated nonlinear dynamics in comparison with the conventional Proportional Integral (PI controller which is typically most effective to handle linear dynamics. The neural controller is designed in such a way that it has the capability of controlling the system generation in the relaxed manner so the ACE is controlled to a desired range instead of driving it to zero which would otherwise increase the control effort and cost; and most importantly the resulting system control performance meets the NERC CPS requirements and/or the NERC Balancing Authority’s ACE Limit (BAAL compliance requirements whichever are applicable.
Castro-Mateos, Isaac; Pozo, Jose M.; Lazary, Aron; Frangi, Alejandro F.
2016-03-01
Computational medicine aims at developing patient-specific models to help physicians in the diagnosis and treatment selection for patients. The spine, and other skeletal structures, is an articulated object, composed of rigid bones (vertebrae) and non-rigid parts (intervertebral discs (IVD), ligaments and muscles). These components are usually extracted from different image modalities, involving patient repositioning. In the case of the spine, these models require the segmentation of IVDs from MR and vertebrae from CT. In the literature, there exists a vast selection of segmentations methods, but there is a lack of approaches to align the vertebrae and IVDs. This paper presents a method to create patient-specific finite element meshes for biomechanical simulations, integrating rigid and non-rigid parts of articulated objects. First, the different parts are aligned in a complete surface model. Vertebrae extracted from CT are rigidly repositioned in between the IVDs, initially using the IVDs location and then refining the alignment using the MR image with a rigid active shape model algorithm. Finally, a mesh morphing algorithm, based on B-splines, is employed to map a template finite-element (volumetric) mesh to the patient-specific surface mesh. This morphing reduces possible misalignments and guarantees the convexity of the model elements. Results show that the accuracy of the method to align vertebrae into MR, together with IVDs, is similar to that of the human observers. Thus, this method is a step forward towards the automation of patient-specific finite element models for biomechanical simulations.
Flandrin, N.
2005-09-15
During the exploitation of an oil reservoir, it is important to predict the recovery of hydrocarbons and to optimize its production. A better comprehension of the physical phenomena requires to simulate 3D multiphase flows in increasingly complex geological structures. In this thesis, we are interested in this spatial discretization and we propose to extend in 3D the 2D hybrid model proposed by IFP in 1998 that allows to take directly into account in the geometry the radial characteristics of the flows. In these hybrid meshes, the wells and their drainage areas are described by structured radial circular meshes and the reservoirs are represented by structured meshes that can be a non uniform Cartesian grid or a Corner Point Geometry grids. In order to generate a global conforming mesh, unstructured transition meshes based on power diagrams and satisfying finite volume properties are used to connect the structured meshes together. Two methods have been implemented to generate these transition meshes: the first one is based on a Delaunay triangulation, the other one uses a frontal approach. Finally, some criteria are introduced to measure the quality of the transition meshes and optimization procedures are proposed to increase this quality under finite volume properties constraints. (author)
Reaction Mechanism Generator: Automatic construction of chemical kinetic mechanisms
Gao, Connie W.; Allen, Joshua W.; Green, William H.; West, Richard H.
2016-06-01
Reaction Mechanism Generator (RMG) constructs kinetic models composed of elementary chemical reaction steps using a general understanding of how molecules react. Species thermochemistry is estimated through Benson group additivity and reaction rate coefficients are estimated using a database of known rate rules and reaction templates. At its core, RMG relies on two fundamental data structures: graphs and trees. Graphs are used to represent chemical structures, and trees are used to represent thermodynamic and kinetic data. Models are generated using a rate-based algorithm which excludes species from the model based on reaction fluxes. RMG can generate reaction mechanisms for species involving carbon, hydrogen, oxygen, sulfur, and nitrogen. It also has capabilities for estimating transport and solvation properties, and it automatically computes pressure-dependent rate coefficients and identifies chemically-activated reaction paths. RMG is an object-oriented program written in Python, which provides a stable, robust programming architecture for developing an extensible and modular code base with a large suite of unit tests. Computationally intensive functions are cythonized for speed improvements.
Kinetic Solvers with Adaptive Mesh in Phase Space
Arslanbekov, Robert R; Kolobov, Vladimir I; Frolova, Anna A.
2013-01-01
An Adaptive Mesh in Phase Space (AMPS) methodology has been developed for solving multi-dimensional kinetic equations by the discrete velocity method. A Cartesian mesh for both configuration (r) and velocity (v) spaces is produced using a tree of trees data structure. The mesh in r-space is automatically generated around embedded boundaries and dynamically adapted to local solution properties. The mesh in v-space is created on-the-fly for each cell in r-space. Mappings between neighboring v-s...
Reinforcement-Based Fuzzy Neural Network ontrol with Automatic Rule Generation
无
1999-01-01
A reinforcemen-based fuzzy neural network control with automatic rule generation RBFNNC) is pro-posed. A set of optimized fuzzy control rules can be automatically generated through reinforcement learning based onthe state variables of object system. RBFNNC was applied to a cart-pole balancing system and simulation resultshows significant improvements on the rule generation.
Automatic Overset Grid Generation with Heuristic Feedback Control
Robinson, Peter I.
2001-01-01
An advancing front grid generation system for structured Overset grids is presented which automatically modifies Overset structured surface grids and control lines until user-specified grid qualities are achieved. The system is demonstrated on two examples: the first refines a space shuttle fuselage control line until global truncation error is achieved; the second advances, from control lines, the space shuttle orbiter fuselage top and fuselage side surface grids until proper overlap is achieved. Surface grids are generated in minutes for complex geometries. The system is implemented as a heuristic feedback control (HFC) expert system which iteratively modifies the input specifications for Overset control line and surface grids. It is developed as an extension of modern control theory, production rules systems and subsumption architectures. The methodology provides benefits over the full knowledge lifecycle of an expert system for knowledge acquisition, knowledge representation, and knowledge execution. The vector/matrix framework of modern control theory systematically acquires and represents expert system knowledge. Missing matrix elements imply missing expert knowledge. The execution of the expert system knowledge is performed through symbolic execution of the matrix algebra equations of modern control theory. The dot product operation of matrix algebra is generalized for heuristic symbolic terms. Constant time execution is guaranteed.
Automatic speech recognition for report generation in computed tomography
Purpose: A study was performed to compare the performance of automatic speech recognition (ASR) with conventional transcription. Materials and Methods: 100 CT reports were generated by using ASR and 100 CT reports were dictated and written by medical transcriptionists. The time for dictation and correction of errors by the radiologist was assessed and the type of mistakes was analysed. The text recognition rate was calculated in both groups and the average time between completion of the imaging study by the technologist and generation of the written report was assessed. A commercially available speech recognition technology (ASKA Software, IBM Via Voice) running of a personal computer was used. Results: The time for the dictation using digital voice recognition was 9.4±2.3 min compared to 4.5±3.6 min with an ordinary Dictaphone. The text recognition rate was 97% with digital voice recognition and 99% with medical transcriptionists. The average time from imaging completion to written report finalisation was reduced from 47.3 hours with medical transcriptionists to 12.7 hours with ASR. The analysis of misspellings demonstrated (ASR vs. medical transcriptionists): 3 vs. 4 for syntax errors, 0 vs. 37 orthographic mistakes, 16 vs. 22 mistakes in substance and 47 vs. erroneously applied terms. Conclusions: The use of digital voice recognition as a replacement for medical transcription is recommendable when an immediate availability of written reports is necessary. (orig.)
Vibrating-mesh nebulization of liposomes generated using an ethanol-based proliposome technology.
Elhissi, Abdelbary; Gill, Hardyal; Ahmed, Waqar; Taylor, Kevin
2011-06-01
This is the first study that evaluates the influence of the compartmental design of the micropump Aeroneb Go nebulizer and the viscosity of a proliposome hydration medium on vibrating-mesh aerosolization of liposomes. Ethanol-based proliposomes comprising soya phosphatidylcholine and cholesterol (1:1 mole ratio) were hydrated by using isotonic NaCl (0.9%) or sucrose (9.25%) solutions to generate liposomes that entrapped approximately 61% of the hydrophilic drug, salbutamol sulphate. Liposomes were aerosolized by the nebulizer to a two-stage impinger. For both formulations, the aerosol mass output was higher than the phospholipid output, indicating some accumulation of large liposomes or liposome aggregate within the nebulizer. Using NaCl (0.9%) solution as the dispersion medium, aerosol droplet size was much smaller and aerosol mass and phospholipid outputs were higher. This was attributed to the lower viscosity of the NaCl solution, resulting in a reduced retention of the aerosols in the "trap" of the nebulizer. For the entrapped salbutamol sulphate, although the "fine particle fraction" was relatively high (57.44%), size reduction of the liposomes during nebulization caused marked losses of the drug originally entrapped. Overall, liposomes generated from proliposomes when using this nebulizer showed high nebulization output and small droplet size. However, further work is required to reduce the losses of the originally entrapped drug from liposomes. PMID:20684671
Automatic ID heat load generation in ANSYS code
Detailed power density profiles are critical in the execution of a thermal analysis using a finite element (FE) code such as ANSYS. Unfortunately, as yet there is no easy way to directly input the precise power profiles into ANSYS. A straight-forward way to do this is to hand-calculate the power of each node or element and then type the data into the code. Every time a change is made to the FE model, the data must be recalculated and reentered. One way to solve this problem is to generate a set of discrete data, using another code such as PHOTON2, and curve-fit the data. Using curve-fitted formulae has several disadvantages. It is time consuming because of the need to run a second code for generation of the data, curve-fitting, and doing the data check, etc. Additionally, because there is no generality for different beamlines or different parameters, the above work must be repeated for each case. And, errors in the power profiles due to curve-fitting result in errors in the analysis. To solve the problem once and for all and with the capability to apply to any insertion device (ID), a program for ED power profile was written in ANSYS Parametric Design Language (APDL). This program is implemented as an ANSYS command with input parameters of peak magnetic field, deflection parameter, length of ID, and distance from the source. Once the command is issued, all the heat load will be automatically generated by the code
A combined procedure for two-dimensional Delaunay mesh generation algorithm and an adaptive remeshing technique with higher-order compressible flow solver is presented. A pseudo-code procedure is described for the adaptive remeshing technique. The flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is proposed. The scheme eliminates nonphysical flow solutions such as the spurious bump of the carbuncle phenomenon observed from the bow shock of the flow over a blunt body and the oscillation in the odd-even grid perturbation in a straight duct for the Quirk's odd-even decoupling test. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. The performance of the combined procedure is evaluated on unstructured triangular meshes by solving several steady-state and transient high-speed compressible flow problems
Development of tools for automatic generation of PLC code
Koutli, Maria; Rochez, Jacques
This Master thesis was performed at CERN and more specifically in the EN-ICE-PLC section. The Thesis describes the integration of two PLC platforms, that are based on CODESYS development tool, to the CERN defined industrial framework, UNICOS. CODESYS is a development tool for PLC programming, based on IEC 61131-3 standard, and is adopted by many PLC manufacturers. The two PLC development environments are, the SoMachine from Schneider and the TwinCAT from Beckhoff. The two CODESYS compatible PLCs, should be controlled by the SCADA system of Siemens, WinCC OA. The framework includes a library of Function Blocks (objects) for the PLC programs and a software for automatic generation of the PLC code based on this library, called UAB. The integration aimed to give a solution that is shared by both PLC platforms and was based on the PLCOpen XML scheme. The developed tools were demonstrated by creating a control application for both PLC environments and testing of the behavior of the code of the library.
Learning Techniques for Automatic Test Pattern Generation using Boolean Satisfiability
Liu Xin
2013-07-01
Full Text Available Automatic Test Pattern Generation (ATPG is one of the core problems in testing of digital circuits. ATPG algorithms based on Boolean Satisfiability (SAT turned out to be very powerful, due to great advances in the performance of satisfiability solvers for propositional logic in the last two decades. SAT-based ATPG clearly outperforms classical approaches especially for hard-to-detect faults. But its inaccessibility of structural information and don’t care, there exists the over-specification problem of input patterns. In this paper we present techniques to delve into an additional layer to make use of structural properties of the circuit and value justification relations to a generic SAT algorithm. It joins binary decision graphs (BDD and SAT techniques to improve the efficiency of ATPG. It makes a study of inexpensive reconvergent fanout analysis of circuit to gather information on the local signal correlation by using BDD learning, then uses the above learned information to restrict and focus the overall search space of SAT-based ATPG. The learning technique is effective and lightweight. Experimental results show the effectiveness of the approach.
Incorporating Feature-Based Annotations into Automatically Generated Knowledge Representations
Lumb, L. I.; Lederman, J. I.; Aldridge, K. D.
2006-12-01
Earth Science Markup Language (ESML) is efficient and effective in representing scientific data in an XML- based formalism. However, features of the data being represented are not accounted for in ESML. Such features might derive from events (e.g., a gap in data collection due to instrument servicing), identifications (e.g., a scientifically interesting area/volume in an image), or some other source. In order to account for features in an ESML context, we consider them from the perspective of annotation, i.e., the addition of information to existing documents without changing the originals. Although it is possible to extend ESML to incorporate feature-based annotations internally (e.g., by extending the XML schema for ESML), there are a number of complicating factors that we identify. Rather than pursuing the ESML-extension approach, we focus on an external representation for feature-based annotations via XML Pointer Language (XPointer). In previous work (Lumb &Aldridge, HPCS 2006, IEEE, doi:10.1109/HPCS.2006.26), we have shown that it is possible to extract relationships from ESML-based representations, and capture the results in the Resource Description Format (RDF). Thus we explore and report on this same requirement for XPointer-based annotations of ESML representations. As in our past efforts, the Global Geodynamics Project (GGP) allows us to illustrate with a real-world example this approach for introducing annotations into automatically generated knowledge representations.
Power generation using carbon mesh cathodes with different diffusion layers in microbial fuel cells
Luo, Yong
2011-11-01
An inexpensive carbon material, carbon mesh, was examined to replace the more expensive carbon cloth usually used to make cathodes in air-cathode microbial fuel cells (MFCs). Three different diffusion layers were tested using carbon mesh: poly(dimethylsiloxane) (PDMS), polytetrafluoroethylene (PTFE), and Goretex cloth. Carbon mesh with a mixture of PDMS and carbon black as a diffusion layer produced a maximum power density of 1355 ± 62 mW m -2 (normalized to the projected cathode area), which was similar to that obtained with a carbon cloth cathode (1390 ± 72 mW m-2). Carbon mesh with a PTFE diffusion layer produced only a slightly lower (6.6%) maximum power density (1303 ± 48 mW m-2). The Coulombic efficiencies were a function of current density, with the highest value for the carbon mesh and PDMS (79%) larger than that for carbon cloth (63%). The cost of the carbon mesh cathode with PDMS/Carbon or PTFE (excluding catalyst and binder costs) is only 2.5% of the cost of the carbon cloth cathode. These results show that low cost carbon materials such as carbon mesh can be used as the cathode in an MFC without reducing the performance compared to more expensive carbon cloth. © 2011 Elsevier B.V.
Automatic generation of digital anthropomorphic phantoms from simulated MRI acquisitions
Lindsay, C.; Gennert, M. A.; KÓ§nik, A.; Dasari, P. K.; King, M. A.
2013-03-01
In SPECT imaging, motion from patient respiration and body motion can introduce image artifacts that may reduce the diagnostic quality of the images. Simulation studies using numerical phantoms with precisely known motion can help to develop and evaluate motion correction algorithms. Previous methods for evaluating motion correction algorithms used either manual or semi-automated segmentation of MRI studies to produce patient models in the form of XCAT Phantoms, from which one calculates the transformation and deformation between MRI study and patient model. Both manual and semi-automated methods of XCAT Phantom generation require expertise in human anatomy, with the semiautomated method requiring up to 30 minutes and the manual method requiring up to eight hours. Although faster than manual segmentation, the semi-automated method still requires a significant amount of time, is not replicable, and is subject to errors due to the difficulty of aligning and deforming anatomical shapes in 3D. We propose a new method for matching patient models to MRI that extends the previous semi-automated method by eliminating the manual non-rigid transformation. Our method requires no user supervision and therefore does not require expert knowledge of human anatomy to align the NURBs to anatomical structures in the MR image. Our contribution is employing the SIMRI MRI simulator to convert the XCAT NURBs to a voxel-based representation that is amenable to automatic non-rigid registration. Then registration is used to transform and deform the NURBs to match the anatomy in the MR image. We show that our automated method generates XCAT Phantoms more robustly and significantly faster than the previous semi-automated method.
Waldrep, J C; Dhand, R
2008-04-01
Recent technological advances and improved nebulizer designs have overcome many limitations of jet nebulizers. Newer devices employ a vibrating mesh or aperture plate (VM/AP) for the generation of therapeutic aerosols with consistent, increased efficiency, predominant aerosol fine particle fractions, low residuals, and the ability to nebulize even microliter volumes. These enhancements are achieved through several different design features and include improvements that promote patient compliance, such as compact design, portability, shorter treatment durations, and quiet operation. Current VM/AP devices in clinical use are the Omron MicroAir, the Nektar Aeroneb, and the Pari eFlow. However, some devices are only approved for use with specific medications. Development of "smart nebulizers" such as the Respironics I-neb couple VM technologies with coordinated delivery and optimized inhalation patterns to enhance inhaled drug delivery of specialized, expensive formulations. Ongoing development of advanced aerosol technologies should improve clinical outcomes and continue to expand therapeutic options as newer inhaled drugs become available. PMID:18393813
Shape Metamorphosis – Automatic 3D Mesh Generation, Topology Verification and Analysis
Tomasz Zawadzki
2013-12-01
Full Text Available The objective of this paper is a 3D shape construction that benefits from discrete and continuous modelling approaches. The proposed solution addresses the problem of automated modelling of virtual structures such as caves, buildings and clouds and presents an alternative solution in the form of a hybrid system. Parallel realizations of these solutions are tested on various processors of graphic cards with the use of NVIDIA ‘CUDA’ technology. This paper describes the implementation of algorithms (approaches and their parallel speedup, efficiency, throughput. Modelled structures are geometrically complex, with an inner graph structure more optimized than in the classical CSG approach. Moreover, they can be rendered up to very high levels of visual realism. In this paper we mainly focus on the description of the algorithm. We also propose very useful measures that can be used to verify the model geometry.
Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)
2013-01-01
Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.
PUS Services Software Building Block Automatic Generation for Space Missions
Candia, S.; Sgaramella, F.; Mele, G.
2008-08-01
The Packet Utilization Standard (PUS) has been specified by the European Committee for Space Standardization (ECSS) and issued as ECSS-E-70-41A to define the application-level interface between Ground Segments and Space Segments. The ECSS-E- 70-41A complements the ECSS-E-50 and the Consultative Committee for Space Data Systems (CCSDS) recommendations for packet telemetry and telecommand. The ECSS-E-70-41A characterizes the identified PUS Services from a functional point of view and the ECSS-E-70-31 standard specifies the rules for their mission-specific tailoring. The current on-board software design for a space mission implies the production of several PUS terminals, each providing a specific tailoring of the PUS services. The associated on-board software building blocks are developed independently, leading to very different design choices and implementations even when the mission tailoring requires very similar services (from the Ground operative perspective). In this scenario, the automatic production of the PUS services building blocks for a mission would be a way to optimize the overall mission economy and improve the robusteness and reliability of the on-board software and of the Ground-Space interactions. This paper presents the Space Software Italia (SSI) activities for the development of an integrated environment to support: the PUS services tailoring activity for a specific mission. the mission-specific PUS services configuration. the generation the UML model of the software building block implementing the mission-specific PUS services and the related source code, support documentation (software requirements, software architecture, test plans/procedures, operational manuals), and the TM/TC database. The paper deals with: (a) the project objectives, (b) the tailoring, configuration, and generation process, (c) the description of the environments supporting the process phases, (d) the characterization of the meta-model used for the generation, (e) the
The geometry of r-adaptive meshes generated using optimal transport methods
Budd, C. J.; Russell, R. D.; Walsh, E.
2015-02-01
The principles of mesh equidistribution and alignment play a fundamental role in the design of adaptive methods, and a metric tensor and mesh metric are useful theoretical tools for understanding a method's level of mesh alignment, or anisotropy. We consider a mesh redistribution method based on the Monge-Ampère equation which combines equidistribution of a given scalar density function with optimal transport. It does not involve explicit use of a metric tensor, although such a tensor must exist for the method, and an interesting question to ask is whether or not the alignment produced by the metric gives an anisotropic mesh. For model problems with a linear feature and with a radially symmetric feature, we derive the exact form of the metric, which involves expressions for its eigenvalues and eigenvectors. The eigenvectors are shown to be orthogonal and tangential to the feature, and the ratio of the eigenvalues (corresponding to the level of anisotropy) is shown to depend, both locally and globally, on the value of the density function and the amount of curvature. We thereby demonstrate how the optimal transport method produces an anisotropic mesh along a given feature while equidistributing a suitably chosen scalar density function. Numerical results are given to verify these results and to demonstrate how the analysis is useful for problems involving more complex features, including for a non-trivial time dependant nonlinear PDE which evolves narrow and curved reaction fronts.
Automatic Grasp Generation and Improvement for Industrial Bin-Picking
Kraft, Dirk; Ellekilde, Lars-Peter; Rytz, Jimmy Alison
2014-01-01
and achieve comparable results and that our learning approach can improve system performance significantly. Automatic bin-picking is an important industrial process that can lead to significant savings and potentially keep production in countries with high labour cost rather than outsourcing it. The presented...... work allows to minimize cycle time as well as setup cost, which are essential factors in automatic bin-picking. It therefore leads to a wider applicability of bin-picking in industry....
Historical Author Affiliations Assist Verification of Automatically Generated MEDLINE® Citations
Sabir, Tehseen F.; Hauser, Susan E.; Thoma, George R.
2006-01-01
High OCR error rates encountered in author affiliations increase the manual labor needed to verify MEDLINE citations automatically created from scanned journal articles. This is due to poor OCR recognition of the small text and italics frequently used in printed affiliations. Using author-affiliation relationships found in existing MEDLINE records, the SeekAffiliation (SA) program automatically finds potentially correct and complete affiliations, thereby reducing manual effort and increasing ...
Automatic Generation of Remote Visualization Tools with WATT
Jensen, P. A.; Bollig, E. F.; Yuen, D. A.; Erlebacher, G.; Momsen, A. R.
2006-12-01
The ever increasing size and complexity of geophysical and other scientific datasets has forced developers to turn to more powerful alternatives for visualizing results of computations and experiments. These alternative need to be faster, scalable, more efficient, and able to be run on large machines. At the same time, advances in scripting languages and visualization libraries have significantly decreased the development time of smaller, desktop visualization tools. Ideally, programmers would be able to develop visualization tools in a high-level, local, scripted environment and then automatically convert their programs into compiled, remote visualization tools for integration into larger computation environments. The Web Automation and Translation Toolkit (WATT) [1] converts a Tcl script for the Visualization Toolkit (VTK) [2] into a standards-compliant web service. We will demonstrate the used of WATT for the automated conversion of a desktop visualization application (written in Tcl for VTK) into a remote visualization service of interest to geoscientists. The resulting service will allow real-time access to a large dataset through the Internet, and will be easily integrated into the existing architecture of the Virtual Laboratory for Earth and Planetary Materials (VLab) [3]. [1] Jensen, P.A., Yuen, D.A., Erlebacher, G., Bollig, E.F., Kigelman, D.G., Shukh, E.A., Automated Generation of Web Services for Visualization Toolkits, Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract IN42A-06, 2005. [2] The Visualization Toolkit, http://www.vtk.org [3] The Virtual Laboratory for Earth and Planetary Materials, http://vlab.msi.umn.edu
Dongmin Seo; Hanmin Jung; Won-Kyung Sung; Dukyun Nam
2014-01-01
By 2026, Korea is expected to surpass the UN’s definition of an aged society and reach the level of a superaged society. With an aging population come increased disorders involving the spine. To prevent unnecessary spinal surgery and support scientific diagnosis of spinal disease and systematic prediction of treatment outcomes, we have been developing e-Spine, which is a computer simulation model of the human spine. In this paper, we present the Korean spine database and automatic surface mes...
How to model wireless mesh networks topology
The specification of network connectivity model or topology is the beginning of design and analysis in Computer Network researches. Wireless Mesh Networks is an autonomic network that is dynamically self-organised, self-configured while the mesh nodes establish automatic connectivity with the adjacent nodes in the relay network of wireless backbone routers. Researches in Wireless Mesh Networks range from node deployment to internetworking issues with sensor, Internet and cellular networks. These researches require modelling of relationships and interactions among nodes including technical characteristics of the links while satisfying the architectural requirements of the physical network. However, the existing topology generators model geographic topologies which constitute different architectures, thus may not be suitable in Wireless Mesh Networks scenarios. The existing methods of topology generation are explored, analysed and parameters for their characterisation are identified. Furthermore, an algorithm for the design of Wireless Mesh Networks topology based on square grid model is proposed in this paper. The performance of the topology generated is also evaluated. This research is particularly important in the generation of a close-to-real topology for ensuring relevance of design to the intended network and validity of results obtained in Wireless Mesh Networks researches
A strategy for automatically generating programs in the lucid programming language
Johnson, Sally C.
1987-01-01
A strategy for automatically generating and verifying simple computer programs is described. The programs are specified by a precondition and a postcondition in predicate calculus. The programs generated are in the Lucid programming language, a high-level, data-flow language known for its attractive mathematical properties and ease of program verification. The Lucid programming is described, and the automatic program generation strategy is described and applied to several example problems.
describe the user's scheme. According to the mesh grid refinement options, GGTM introduces further co-ordinate values, which complete the input mesh grid. A loop for each cell is performed to determine the zone and the material to be attributed to the cell. The cell is ideally represented by its centre and it is relatively simple to determine which material zone the cell belongs to. Material zones may have very complicated geometrical shapes in space thanks to the combinatorial geometry among volumes existing in GGTM. Moreover, the priority parameter associated to each material zone can easily solve any overlapping situation among zones. Fixed neutron sources, if any, are adapted to the mesh refinement at the same time. As from version 5.0, GGTM can optionally calculate errors in volume values due to the stair-cased approximation in geometry. GGTM considers a 'very' refined uniform sub-grid for those single meshes cutting more than one material zone at zone interfaces and works in same way as previously described in the mesh attribution to zones for each single sub-mesh. This method lets users calculate the exact material zone volume values with great precision, independently of the geometry complexity and lets GGTM automatically update material zone densities to conserve mass. As for the plot programs DDM, DTM2 and DTM3, they do not make any value interpolations among cell values to have contours, when used as post-processors or to plot any fixed neutron source distribution; they simply attribute the entire single mesh grid cell the colour corresponding to the adopted value scale. This simple and fast method lets users faithfully reproduce transport results and overlap material, zone, body or mesh borders on the same plots without overcrowding them with too many lines. 3 - Restrictions on the complexity of the problem: Only a continuous space mesh grid can be generated by GGDM and GGTM and input to DDM, DTM2, DTM3, RVARSCL, COMPARE and MKSRC
Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automatize all processes that contribute to diagnosis. This paper describes how we use signal processing, pattern recognition and artificial intelligence to build a software package that is able to automatically provide an efficient diagnosis. (authors). 2 figs., 5 refs
An efficient hydraulic optimization procedure, suitable for industrial use, requires an advanced optimization tool (EASY software), a fast solver (block coupled CFD) and a flexible geometry generation tool. EASY optimization software is a PCA-driven metamodel-assisted Evolutionary Algorithm (MAEA (PCA)) that can be used in both single- (SOO) and multiobjective optimization (MOO) problems. In MAEAs, low cost surrogate evaluation models are used to screen out non-promising individuals during the evolution and exclude them from the expensive, problem specific evaluation, here the solution of Navier-Stokes equations. For additional reduction of the optimization CPU cost, the PCA technique is used to identify dependences among the design variables and to exploit them in order to efficiently drive the application of the evolution operators. To further enhance the hydraulic optimization procedure, a very robust and fast Navier-Stokes solver has been developed. This incompressible CFD solver employs a pressure-based block-coupled approach, solving the governing equations simultaneously. This method, apart from being robust and fast, also provides a big gain in terms of computational cost. In order to optimize the geometry of hydraulic machines, an automatic geometry and mesh generation tool is necessary. The geometry generation tool used in this work is entirely based on b-spline curves and surfaces. In what follows, the components of the tool chain are outlined in some detail and the optimization results of hydraulic machine components are shown in order to demonstrate the performance of the presented optimization procedure
Automated Theorem Proving for Cryptographic Protocols with Automatic Attack Generation
Jan Juerjens; Thomas A. Kuhn
2016-01-01
Automated theorem proving is both automatic and can be quite efficient. When using theorem proving approaches for security protocol analysis, however, the problem is often that absence of a proof of security of a protocol may give little hint as to where the security weakness lies, to enable the protocol designer to improve the protocol. For our approach to verify cryptographic protocols using automated theorem provers for first-order logic (such as e-SETHEO or SPASS), we demonstrate a method...
Research on Object-oriented Software Testing Cases of Automatic Generation
Junli Zhang
2013-11-01
Full Text Available In the research on automatic generation of testing cases, there are different execution paths under drivers of different testing cases. The probability of these paths being executed is also different. For paths which are easy to be executed, more redundant testing case tend to be generated; But only fewer testing cases are generated for the control paths which are hard to be executed. Genetic algorithm can be used to instruct the automatic generation of testing cases. For the former paths, it can restrict the generation of these kinds of testing cases. On the contrary, the algorithm will encourage the generation of such testing cases as much as possible. So based on the study on the technology of path-oriented testing case automatic generation, the genetic algorithm is adopted to construct the process of automatic generation. According to the triggering path during the dynamic execution of program, the generated testing cases are separated into different equivalence class. The number of testing case is adjusted dynamicly by the fitness corresponding to the paths. The method can create a certain number of testing cases for each execution path to ensure the sufficiency. It also reduces redundant testing cases so it is an effective method for automatic generation of testing cases.
National Aeronautics and Space Administration — The following background technology is described in Part 5: Run-time Verification (RV), White Box Automatic Test Generation (WBATG). Part 5 also describes how WBATG...
Isotropic 2D quadrangle meshing with size and orientation control
Pellenard, Bertrand
2011-12-01
We propose an approach for automatically generating isotropic 2D quadrangle meshes from arbitrary domains with a fine control over sizing and orientation of the elements. At the heart of our algorithm is an optimization procedure that, from a coarse initial tiling of the 2D domain, enforces each of the desirable mesh quality criteria (size, shape, orientation, degree, regularity) one at a time, in an order designed not to undo previous enhancements. Our experiments demonstrate how well our resulting quadrangle meshes conform to a wide range of input sizing and orientation fields.
The challenge of Automatic Level Generation for platform videogames based on Stories and Quests
Mourato, Fausto; Birra, Fernando; Santos, Manuel Próspero dos
2013-01-01
In this article we bring the concepts of narrativism and ludology to automatic level generation for platform videogames. The initial motivation is to understand how this genre has been used as a storytelling medium. Based on a narrative theory of games, the differences among several titles have been identified. In addition, we propose a set of abstraction layers to describe the content of a quest-based story in the particular context of videogames. Regarding automatic level generation for pla...
A system for automatically generating documentation for (C)LP programs
Hermenegildo, Manuel V.
2000-01-01
We describe lpdoc, a tool which generates documentation manuals automatically from one or more logic program source files, written in ISO-Prolog, Ciao, and other (C)LP languages. It is particularly useful for documenting library modules, for which it automatically generates a rich description of the module interface. However, it can also be used quite successfully to document full applications. A fundamental advantage of using lpdoc is that it helps maintaining a true correspondence between t...
梁松新; 张景中
1999-01-01
By establishing a complete discrimination system for polynomials, the problem of complete root classification for polynomials with complex coefficients is utterly solved, furthermore, the algorithm obtained is made into a general program in Maple, which enables the complete discrimination system and complete root classification of a polynomial to be automatically generated by computer, without any human intervention. Besides, by using the automatic generation of root classification, a method to determine the positive definiteness of a polynomial in one or two indeterminates is automatically presented.
Kinetic Solvers with Adaptive Mesh in Phase Space
Arslanbekov, Robert R; Frolova, Anna A
2013-01-01
An Adaptive Mesh in Phase Space (AMPS) methodology has been developed for solving multi-dimensional kinetic equations by the discrete velocity method. A Cartesian mesh for both configuration (r) and velocity (v) spaces is produced using a tree of trees data structure. The mesh in r-space is automatically generated around embedded boundaries and dynamically adapted to local solution properties. The mesh in v-space is created on-the-fly for each cell in r-space. Mappings between neighboring v-space trees implemented for the advection operator in configuration space. We have developed new algorithms for solving the full Boltzmann and linear Boltzmann equations with AMPS. Several recent innovations were used to calculate the full Boltzmann collision integral with dynamically adaptive mesh in velocity space: importance sampling, multi-point projection method, and the variance reduction method. We have developed an efficient algorithm for calculating the linear Boltzmann collision integral for elastic and inelastic...
In this paper, we propose a new approach to the development of the automatic vision system to examine and repair the steam generator tubes at remote distance. In nuclear power plants, workers are reluctant of works in steam generator because of the high radiation environment and limited working space. It is strongly recommended that the examination and maintenance works be done by an automatic system for the protection of the operator from the radiation exposure. Digital signal processors are used in implementing real time recognition and examination of steam generator tubes in the proposed vision system. Performance of proposed digital vision system is illustrated by simulation and experiment for similar steam generator model
Automatic Generation Control Strategy Based on Balance of Daily Electric Energy
无
2005-01-01
An automatic generation control strategy based on balance of daily total electric energy is put forward. It makes the balance between actual total generated energy controlled by automatic generation system and planned total energy on base of area control error, and makes the actual 24-hour active power load curve to approach the planned load curve. The generated energy is corrected by velocity weighting factor so that it conducts dynamic regulation and reaches the speed of response. Homologous strategy is used according to the real-time data in the operation of automatic generation control. Results of simulation are perfect and power energy compensation control with ideal effect can be achieved in the particular duration.
AROMA: Automatic Generation of Radio Maps for Localization Systems
Eleryan, Ahmed; Youssef, Moustafa
2010-01-01
WLAN localization has become an active research field recently. Due to the wide WLAN deployment, WLAN localization provides ubiquitous coverage and adds to the value of the wireless network by providing the location of its users without using any additional hardware. However, WLAN localization systems usually require constructing a radio map, which is a major barrier of WLAN localization systems' deployment. The radio map stores information about the signal strength from different signal strength streams at selected locations in the site of interest. Typical construction of a radio map involves measurements and calibrations making it a tedious and time-consuming operation. In this paper, we present the AROMA system that automatically constructs accurate active and passive radio maps for both device-based and device-free WLAN localization systems. AROMA has three main goals: high accuracy, low computational requirements, and minimum user overhead. To achieve high accuracy, AROMA uses 3D ray tracing enhanced wi...
Improving Statistical Language Model Performance with Automatically Generated Word Hierarchies
McMahon, J; Mahon, John Mc
1995-01-01
An automatic word classification system has been designed which processes word unigram and bigram frequency statistics extracted from a corpus of natural language utterances. The system implements a binary top-down form of word clustering which employs an average class mutual information metric. Resulting classifications are hierarchical, allowing variable class granularity. Words are represented as structural tags --- unique $n$-bit numbers the most significant bit-patterns of which incorporate class information. Access to a structural tag immediately provides access to all classification levels for the corresponding word. The classification system has successfully revealed some of the structure of English, from the phonemic to the semantic level. The system has been compared --- directly and indirectly --- with other recent word classification systems. Class based interpolated language models have been constructed to exploit the extra information supplied by the classifications and some experiments have sho...
Generation of the 30 M-Mesh Global Digital Surface Model by Alos Prism
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.
Automatic Test case Generation from UML Activity Diagrams
V.Mary Sumalatha*1; Dr G.S.V.P.Raju2
2014-01-01
Test Case Generation is an important phase in software development. Nowadays much of the research is done on UML diagrams for generating test cases. Activity diagrams are different from flow diagrams in the fact that activity diagrams express parallel behavior which flow diagrams cannot express. This paper concentrates on UML 2.0 Activity Diagram for generating test cases. Fork and join pair in activity diagram are used to represent concurrent activities. A novel method is pro...
AUTOMATIC BIOMASS BOILER WITH AN EXTERNAL THERMOELECTRIC GENERATOR
Marian Brázdil; Ladislav Šnajdárek; Petr Kracík; Jirí Pospíšil
2014-01-01
This paper presents the design and test results of an external thermoelectric generator that utilizes the waste heat from a small-scale domestic biomass boiler with nominal rated heat output of 25 kW. The low-temperature Bi2Te3 generator based on thermoelectric modules has the potential to recover waste heat from gas combustion products as effective energy. The small-scale generator is constructed from independent segments. Measurements have shown that up to 11 W of electricity can be generat...
Chan, William M.; Akien, Edwin (Technical Monitor)
2002-01-01
For many years, generation of overset grids for complex configurations has required the use of a number of different independently developed software utilities. Results created by each step were then visualized using a separate visualization tool before moving on to the next. A new software tool called OVERGRID was developed which allows the user to perform all the grid generation steps and visualization under one environment. OVERGRID provides grid diagnostic functions such as surface tangent and normal checks as well as grid manipulation functions such as extraction, extrapolation, concatenation, redistribution, smoothing, and projection. Moreover, it also contains hyperbolic surface and volume grid generation modules that are specifically suited for overset grid generation. It is the first time that such a unified interface existed for the creation of overset grids for complex geometries. New concepts on automatic overset surface grid generation around surface discontinuities will also be briefly presented. Special control curves on the surface such as intersection curves, sharp edges, open boundaries, are called seam curves. The seam curves are first automatically extracted from a multiple panel network description of the surface. Points where three or more seam curves meet are automatically identified and are called seam corners. Seam corner surface grids are automatically generated using a singular axis topology. Hyperbolic surface grids are then grown from the seam curves that are automatically trimmed away from the seam corners.
BOT3P consists of a set of standard Fortran 77 language programs that gives the users of the deterministic transport codes DORT, TORT, TWODANT, THREEDANT, PARTISN and the sensitivity code SUSD3D some useful diagnostic tools to prepare and check the geometry of their input data files for both Cartesian and cylindrical geometries, including graphical display modules. Users can produce the geometrical and material distribution data for all the cited codes for both two-dimensional and three-dimensional applications and, only in 3-dimensional Cartesian geometry, for the Monte Carlo Transport Code MCNP, starting from the same BOT3P input. Moreover, BOT3P stores the fine mesh arrays and the material zone map in a binary file, the content of which can be easily interfaced to any deterministic and Monte Carlo transport code. This makes it possible to compare directly for the same geometry the effects stemming from the use of different data libraries and solution approaches on transport analysis results. BOT3P Version 5.0 lets users optionally and with the desired precision compute the area/volume error of material zones with respect to the theoretical values, if any, because of the stair-cased representation of the geometry, and automatically update material densities on the whole zone domains to conserve masses. A local (per mesh) density correction approach is also available. BOT3P is designed to run on Linux/UNIX platforms and is publicly available from the Organization for Economic Cooperation and Development (OECD/NEA)/Nuclear Energy Agency Data Bank. Through the use of BOT3P, radiation transport problems with complex 3-dimensional geometrical structures can be modelled easily, as a relatively small amount of engineer-time is required and refinement is achieved by changing few parameters. This tool is useful for solving very large challenging problems, as successfully demonstrated not only in some complex neutron shielding and criticality benchmarks but also in a power
Finite element speaker-specific face model generation for the study of speech production.
Bucki, Marek; Nazari, Mohammad Ali; Payan, Yohan
2010-01-01
International audience In situations where automatic mesh generation is unsuitable, the finite element (FE) mesh registration technique known as mesh-match-and-repair (MMRep) is an interesting option for quickly creating a subject-specific FE model by fitting a predefined template mesh onto the target organ. The irregular or poor quality elements produced by the elastic deformation are corrected by a 'mesh reparation' procedure ensuring that the desired regularity and quality standards are...
Towards a Pattern-based Automatic Generation of Logical Specifications for Software Models
Klimek, Radoslaw
2014-01-01
The work relates to the automatic generation of logical specifications, considered as sets of temporal logic formulas, extracted directly from developed software models. The extraction process is based on the assumption that the whole developed model is structured using only predefined workflow patterns. A method of automatic transformation of workflow patterns to logical specifications is proposed. Applying the presented concepts enables bridging the gap between the benefits of deductive rea...
Validating EHR documents: automatic schematron generation using archetypes.
Pfeiffer, Klaus; Duftschmid, Georg; Rinner, Christoph
2014-01-01
The goal of this study was to examine whether Schematron schemas can be generated from archetypes. The openEHR Java reference API was used to transform an archetype into an object model, which was then extended with context elements. The model was processed and the constraints were transformed into corresponding Schematron assertions. A prototype of the generator for the reference model HL7 v3 CDA R2 was developed and successfully tested. Preconditions for its reusability with other reference models were set. Our results indicate that an automated generation of Schematron schemas is possible with some limitations. PMID:24825691
Medical Image Processing for Fully Integrated Subject Specific Whole Brain Mesh Generation
Chih-Yang Hsu; Ben Schneller; Mahsa Ghaffari; Ali Alaraj; Andreas Linninger
2015-01-01
Currently, anatomically consistent segmentation of vascular trees acquired with magnetic resonance imaging requires the use of multiple image processing steps, which, in turn, depend on manual intervention. In effect, segmentation of vascular trees from medical images is time consuming and error prone due to the tortuous geometry and weak signal in small blood vessels. To overcome errors and accelerate the image processing time, we introduce an automatic image processing pipeline for construc...
On the Support of Multimedia Applications over Wireless Mesh Networks
Chemseddine BEMMOUSSAT
2013-05-01
Full Text Available For next generation wireless networks, supporting quality of service (QoS in multimedia application likevideo, streaming and voice over IP is a necessary and critical requirement. Wireless Mesh Networking isenvisioned as a solution for next networks generation and a promising technology for supportingmultimedia application.With decreasing the numbers of mesh clients, QoS will increase automatically. Several research arefocused to improve QoS in Wireless Mesh networks (WMNs, they try to improve a basics algorithm, likerouting protocols or one of example of canal access, but in moments it no sufficient to ensure a robustsolution to transport multimedia application over WMNs.In this paper we propose an efficient routing algorithm for multimedia transmission in the mesh networkand an approach of QoS in the MAC layer for facilitated transport video over the network studied.
Impact of automatic threshold capture on pulse generator longevity
CHEN Ruo-han; CHEN Ke-ping; WANG Fang-zheng; HUA Wei; ZHANG Shu
2006-01-01
Background The automatic, threshold tracking, pacing algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response following each pacemaker stimulus. This function was assumed to be not only energy saving but safe. This study estimated the extension in longevity obtained by AutoCapture (AC) compared with pacemakers programmed to manually optimized, nominal output.Methods Thirty-four patients who received the St. Jude Affinity series pacemaker were included in the study.The following measurements were taken: stimulation and sensing threshold, impedance of leads, evoked response and polarization signals by 3501 programmer during followup, battery current and battery impedance under different conditions. For longevity comparison, ventricular output was programmed under three different conditions: (1) AC on; (2) AC off with nominal output, and (3) AC off with pacing output set at twice the pacing threshold with a minimum of 2.0 V. Patients were divided into two groups: chronic threshold is higher or lower than 1 V. The efficacy of AC was evaluated.Results Current drain in the AC on group, AC off with optimized programming or nominal output was (14.33±2.84) mA, (16.74±2.75) mA and (18.4±2.44) mA, respectively (AC on or AC off with optimized programming vs. nominal output, P ＜ 0.01). Estimated longevity was significantly extended by AC on when compared with nominal setting [(103 ± 27) months, (80 ± 24) months, P ＜ 0.01). Furthermore, compared with the optimized programming, AC extends the longevity when the pacing threshold is higher than 1 V.Conclusion AC could significantly prolong pacemaker longevity; especially in the patient with high pacing threshold.
Power generation using an activated carbon and metal mesh cathode in a microbial fuel cell
Zhang, Fang
2009-11-01
An inexpensive activated carbon (AC) air cathode was developed as an alternative to a platinum-catalyzed electrode for oxygen reduction in a microbial fuel cell (MFC). AC was cold-pressed with a polytetrafluoroethylene (PTFE) binder to form the cathode around a Ni mesh current collector. This cathode construction avoided the need for carbon cloth or a metal catalyst, and produced a cathode with high activity for oxygen reduction at typical MFC current densities. Tests with the AC cathode produced a maximum power density of 1220 mW/m2 (normalized to cathode projected surface area; 36 W/m3 based on liquid volume) compared to 1060 mW/m2 obtained by Pt catalyzed carbon cloth cathode. The Coulombic efficiency ranged from 15% to 55%. These findings show that AC is a cost-effective material for achieving useful rates of oxygen reduction in air cathode MFCs. © 2009 Elsevier B.V. All rights reserved.
Shoreline and Bathymetry Approximation in Mesh Generation for Tidal Renewable Simulations
Avdis, Alexandros; Hill, Jon; Piggott, Matthew D; Gorman, Gerard J
2015-01-01
Due to the fractal nature of the domain geometry in geophysical flow simulations, a completely accurate description of the domain in terms of a computational mesh is frequently deemed infeasible. Shoreline and bathymetry simplification methods are used to remove small scale details in the geometry, particularly in areas away from the region of interest. To that end, a novel method for shoreline and bathymetry simplification is presented. Existing shoreline simplification methods typically remove points if the resultant geometry satisfies particular geometric criteria. Bathymetry is usually simplified using traditional filtering techniques, that remove unwanted Fourier modes. Principal Component Analysis (PCA) has been used in other fields to isolate small-scale structures from larger scale coherent features in a robust way, underpinned by a rigorous but simple mathematical framework. Here we present a method based on principal component analysis aimed towards simplification of shorelines and bathymetry. We pr...
AN ALGORITHM FOR AUTOMATICALLY GENERATING BLACK-BOX TEST CASES
Xu Baowen; Nie Changhai; Shi Qunfeng; Lu Hong
2003-01-01
Selection of test cases plays a key role in improving testing efficiency. Black-box testing is an important way of testing, and its validity lies on the selection of test cases in some sense. A reasonable and effective method about the selection and generation of test cases is urgently needed. This letter first introduces some usualmethods on black-box test case generation,then proposes a new algorithm based on interface parameters and discusses its properties, finally shows the effectiveness of the algorithm.
AN ALGORITHM FOR AUTOMATICALLY GENERATING BLACK－BOX TEST CASES
XuBaowen; NieChanghai; 等
2003-01-01
Selection of test cases plays a key role in improving testing efficiency.Black-box testing is an important way of testing,and is validity lies on the secection of test cases in some sense.A reasonable and effective method about the selection and generation of test cascs is urgently needed.This letter first introduces some usual methods on black-box test case generation,then proposes a new glgorithm based on interface parameters and discusses its properties,finally shows the effectiveness of the algorithm.