WorldWideScience

Sample records for publication types mesh

  1. The MESH approach: strengthening public health systems for the MDGs.

    Science.gov (United States)

    Thomas, Stephen; Mooney, Gavin; Mbatsha, Sandi

    2007-10-01

    This article addresses some of the complexities in the interactions both within the public health system and between that and civil society. It examines what needs to be done to improve the capacity of health systems, primarily through building relevant infrastructure (what is called MESH--management, economic, social and human - infrastructure) where this is lacking. This lack is most likely to occur in poorer communities and health districts. The problem of absorption and appropriate use of funds in disadvantaged areas has been highlighted as a critical bottleneck to the achievement of the millennium development goals (MDGs). MESH is defined as infrastructure which is built to improve the capacity of communities and other entities to implement health service programs efficiently. We employ this concept to determine how best to invest in health in poor areas so that they can better use any additional resources they receive. The article reviews some initial explorations of the relevance of MESH building strategies in South Africa. The research shows the usefulness of the MESH approach which requires inter alia a more developmental approach that goes beyond the vertical silos of much influential prioritization literature over the last two decades. In practice it is clear that MESH will vary from location to location which reflects the fact that investing in successful health strategies must take into account the voices of the local people with respect to what they want from their health services.

  2. The search for ideal hernia repair; mesh materials and types.

    Science.gov (United States)

    Bilsel, Yilmaz; Abci, Ilker

    2012-01-01

    Hernia surgery continues to draw the attention of surgeons, patients, and the industry. This strong interest has driven the establishment of professional medical societies with the sole purpose of furthering the understanding of hernias and hernia repair. In the more than 100 years of development, industry has played a major role in advancing the technology to perfect the performance of hernia repair with the hope of establishing the "best" technique and its associated technology. However, with the development of newer prosthetics and approaches to hernia repair, many surgeons do not fully understand the properties of the available prosthetics. The goal of this review is to highlight the different types of meshes in an effort to clarify to surgeons what types of materials are available to them and how to select an appropriate one for a given case.

  3. Development of skeletal system for mesh-type ICRP reference adult phantoms

    Science.gov (United States)

    Yeom, Yeon Soo; Wang, Zhao Jun; Tat Nguyen, Thang; Kim, Han Sung; Choi, Chansoo; Han, Min Cheol; Kim, Chan Hyeong; Lee, Jai Ki; Chung, Beom Sun; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik

    2016-10-01

    The reference adult computational phantoms of the international commission on radiological protection (ICRP) described in Publication 110 are voxel-type computational phantoms based on whole-body computed tomography (CT) images of adult male and female patients. The voxel resolutions of these phantoms are in the order of a few millimeters and smaller tissues such as the eye lens, the skin, and the walls of some organs cannot be properly defined in the phantoms, resulting in limitations in dose coefficient calculations for weakly penetrating radiations. In order to address the limitations of the ICRP-110 phantoms, an ICRP Task Group has been recently formulated and the voxel phantoms are now being converted to a high-quality mesh format. As a part of the conversion project, in the present study, the skeleton models, one of the most important and complex organs of the body, were constructed. The constructed skeleton models were then tested by calculating red bone marrow (RBM) and endosteum dose coefficients (DCs) for broad parallel beams of photons and electrons and comparing the calculated values with those of the original ICRP-110 phantoms. The results show that for the photon exposures, there is a generally good agreement in the DCs between the mesh-type phantoms and the original voxel-type ICRP-110 phantoms; that is, the dose discrepancies were less than 7% in all cases except for the 0.03 MeV cases, for which the maximum difference was 14%. On the other hand, for the electron exposures (⩽4 MeV), the DCs of the mesh-type phantoms deviate from those of the ICRP-110 phantoms by up to ~1600 times at 0.03 MeV, which is indeed due to the improvement of the skeletal anatomy of the developed skeleton mesh models.

  4. On the Meshing Efficiency of 2K-2H Type Planetary Gear Reducer

    OpenAIRE

    Long-Chang Hsieh; Hsiu-Chen Tang

    2013-01-01

    This paper proposes 2K-2H type planetary gear reducer and analyzes its meshing efficiency. First, according to the concept of train value equation, the kinematic design of 2K-2H type planetary gear reducers is carried out. Three 2K-2H type planetary gear reducers are designed to illustrate the design algorithm. Then, based on the latent power theorem, the meshing efficiency equation of 2K-2H type planetary gear reducer is derived. According to the meshing efficiency equation, the meshing effi...

  5. On the Meshing Efficiency of 2K-2H Type Planetary Gear Reducer

    Directory of Open Access Journals (Sweden)

    Long-Chang Hsieh

    2013-01-01

    Full Text Available This paper proposes 2K–2H type planetary gear reducer and analyzes its meshing efficiency. First, according to the concept of train value equation, the kinematic design of 2K–2H type planetary gear reducers is carried out. Three 2K–2H type planetary gear reducers are designed to illustrate the design algorithm. Then, based on the latent power theorem, the meshing efficiency equation of 2K–2H type planetary gear reducer is derived. According to the meshing efficiency equation, the meshing efficiencies of 2K–2H type planetary gear reducers are analyzed. The 2K–2H type planetary gear reducer has the following characteristics. (1 There is a power circulation in 2K–2H type planetary gear reducer. (2 Larger reduction ratio makes less meshing efficiency. (3 For the same reduction ratio, larger value ξ42 (ξα will get better meshing efficiency. (4 For 2K–2H type planetary gear reducer, the quality of gears is an important factor. (5 The efficiency of gears manufactured by grinding is only improved by 1.5%; however, meshing efficiency of 2K–2H type planetary gear reducer is improved by 28%~44.8%.

  6. Modelling axisymmetric cod-ends made of different mesh types

    DEFF Research Database (Denmark)

    Priour, D.; Herrmann, Bent; O'Neill, F.G.

    2009-01-01

    Cod-ends are the rearmost part of trawl fishing gears. They collect the catch, and for many important species it is where fish selection takes place. Generally speaking they are axisymmetric, and their shape is influenced by the catch volume, the mesh shape, and the material characteristics. The ...

  7. Publication trends in the medical informatics literature: 20 years of "Medical Informatics" in MeSH

    Directory of Open Access Journals (Sweden)

    LaVallie Donna L

    2009-01-01

    Full Text Available Abstract Background The purpose of this study is to identify publication output, and research areas, as well as descriptively and quantitatively characterize the field of medical informatics through publication trend analysis over a twenty year period (1987–2006. Methods A bibliometric analysis of medical informatics citations indexed in Medline was performed using publication trends, journal frequency, impact factors, MeSH term frequencies and characteristics of citations. Results There were 77,023 medical informatics articles published during this 20 year period in 4,644 unique journals. The average annual article publication growth rate was 12%. The 50 identified medical informatics MeSH terms are rarely assigned together to the same document and are almost exclusively paired with a non-medical informatics MeSH term, suggesting a strong interdisciplinary trend. Trends in citations, journals, and MeSH categories of medical informatics output for the 20-year period are summarized. Average impact factor scores and weighted average impact factor scores increased over the 20-year period with two notable growth periods. Conclusion There is a steadily growing presence and increasing visibility of medical informatics literature over the years. Patterns in research output that seem to characterize the historic trends and current components of the field of medical informatics suggest it may be a maturing discipline, and highlight specific journals in which the medical informatics literature appears most frequently, including general medical journals as well as informatics-specific journals.

  8. Superconvergence of a Nonconforming Finite Element Approximation to Viscoelasticity Type Equations on Anisotropic Meshes

    Institute of Scientific and Technical Information of China (English)

    Dongyang Shi; Yucheng Peng; Shaochun Chen

    2006-01-01

    The main aim of this paper is to study the approximation to viscoelasticity type equations with a Crouzeix-Raviart type nonconforming finite element on the anisotropic meshes. The superclose property of the exact solution and the optimal error estimate of its derivative with respect to time are derived by using some novel techniques. Moreover,employing a postprocessing technique, the global superconvergence property for the discretization error of the postprocessed discrete solution to the solution itself is studied.

  9. Development of display-type ellipsoidal mesh analyzer: Computational evaluation and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, H., E-mail: hmatsuda@ms.naist.jp [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Goto, K. [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Tóth, L. [University of Debrecen, H-4032 Debrecen, Egyetem ter 1 (Hungary); Morita, M.; Kitagawa, S.; Matsui, F.; Hashimoto, M.; Sakai, C. [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Matsushita, T. [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Koto, Sayo, Hyogo 679-5198 (Japan); Daimon, H. [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)

    2014-08-15

    An advanced measurement system for two-dimensional photoelectron spectroscopy has been developed to overcome the difficulties faced in the display-type spherical-mirror analyzer (DIANA) having been used so far. One difficulty is to realize selected small area analysis and another is to obtain higher energy resolution. The developed system, which we call “display-type ellipsoidal mesh analyzer (DELMA)”, has an ellipsoidal mesh electrode as its key element, which allows a wide acceptance angle (>∼ ±45°) comparable to that of DIANA. In this paper we provide details of DELMA on its design and performance. For the imaging performance, we evaluated, using ray-tracing, some important factors that can affect the spatial resolution: off-axis aberration, the effect of shape and position errors, the disturbing effect of mesh holes, and chromatic aberration. In test experiments, a spatial resolution of around 20–30 μm was obtained. The ray-tracing results suggest that this resolution can be improved to be less than 10 μm by decreasing the size of mesh holes and the error of the mesh shape. We also provide computational results for the energy resolution obtained in various conditions. It depends not only on the size of the energy-selecting aperture but also on the size and shape of an irradiation spot. Experimental results for the energy resolution were in good agreement with computational results. An available resolution seems to be as good as in DIANA (∼0.5%). A much better resolution is possible in our system by the combination of DELMA and a high resolution concentric hemispherical analyzer. In test experiments using an angle-measurement device, a wide acceptance angle of around ±45° has been successfully confirmed. As a practical example of the angular analysis by DELMA, a photoelectron diffraction pattern measured for single crystalline graphite is shown.

  10. Inclusion of thin target and source regions in alimentary and respiratory tract systems of mesh-type ICRP adult reference phantoms

    Science.gov (United States)

    Kim, Han Sung; Yeom, Yeon Soo; Tat Nguyen, Thang; Choi, Chansoo; Han, Min Cheol; Lee, Jai Ki; Kim, Chan Hyeong; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik; Qiu, Rui; Eckerman, Keith; Chung, Beom Sun

    2017-03-01

    It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.

  11. Preconditioning and Uniform Convergence for Convection-Diffusion Problems Discretized on Shishkin-Type Meshes

    Directory of Open Access Journals (Sweden)

    Thái Anh Nhan

    2016-01-01

    Full Text Available A one-dimensional linear convection-diffusion problem with a perturbation parameter ɛ multiplying the highest derivative is considered. The problem is solved numerically by using the standard upwind scheme on special layer-adapted meshes. It is proved that the numerical solution is ɛ-uniform accurate in the maximum norm. This is done by a new proof technique in which the discrete system is preconditioned in order to enable the use of the principle where “ɛ-uniform stability plus ɛ-uniform consistency implies ɛ-uniform convergence.” Without preconditioning, this principle cannot be applied to convection-diffusion problems because the consistency error is not uniform in ɛ. At the same time, the condition number of the discrete system becomes independent of ɛ due to the same preconditioner; otherwise, the condition number of the discrete system before preconditioning increases when ɛ tends to 0. We obtained such results in an earlier paper, but only for the standard Shishkin mesh. In a nontrivial generalization, we show here that the same proof techniques can be applied to the whole class of Shishkin-type meshes.

  12. Development of skeleton model for use in polygonal-mesh-type ICRP reference phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thang Tat; Yeom, Yeon Soo; Han, Min Cheol; Wang, Zhao Jun; Kim, Han Sung; Kim, Chan Hyeong [Dept.of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2015-04-15

    In order to overcome the limitations, we are currently developing the polygonal-mesh versions of the ICRP reference phantoms by converting the ICRP reference voxel phantoms to polygonal-mesh format. As a part of the ICRP reference phantom conversion project, the present study completed the conversion of skeleton, which is a very complex framework of the body, while addressing some critical problems of the skeleton of the ICRP reference voxel phantoms. The converted skeleton models were also evaluated by comparing dose values of RBM and endosteum with those of the ICRP reference voxel phantoms. As a part of the ICRP reference phantom conversion project, the present study successfully completed skeleton conversion of the ICRP reference adult male and female phantoms to polygonal-mesh format. A comprehensive study of dosimetric effects by the skeleton conversion will be performed in the future.

  13. Opfront: mesh

    DEFF Research Database (Denmark)

    2015-01-01

    Mesh generation and visualization software based on the CGAL library. Folder content: drawmesh Visualize slices of the mesh (surface/volumetric) as wireframe on top of an image (3D). drawsurf Visualize surfaces of the mesh (surface/volumetric). img2mesh Convert isosurface in image to volumetric...

  14. Contributions in the Preparation and Processing of Composite Material Type Silumin 3 - Reinforced Matrix with S235JR Steel Mesh

    Directory of Open Access Journals (Sweden)

    Remus Belu-Nica

    2015-07-01

    Full Text Available In the paper are presented concrete data on developing technological batches of metal composite material (MCM type Silumin 3-reinforced matrix with steel mesh S235JR, with the indicating of the parameter and of the distinct stages of work. The samples from prepared batches were cut along and across by water jet abrasive process and were subjected to a destructive testing program and microstructural examination, obtaining results in concordance with the desired quality. The abrasive material used for cut was GMA granite with the average mesh of 80, the particle size ranging between 150-300 µm, density 2300 kg/m3 and melting point 1240°C.

  15. Indexing Publicly Available Health Data with Medical Subject Headings (MeSH): An Evaluation of Term Coverage.

    Science.gov (United States)

    Marc, David T; Zhang, Rui; Beattie, James; Gatewood, Laël C; Khairat, Saif S

    2015-01-01

    As part of the Open Government Initiative, the United States federal government published datasets to increase collaboration, transparency, consumer participation, and research, and are available online at HealthData.gov. Currently, HealthData.gov does not adequately support the accessibility goal of the Open Government Initiative due to issues of retrieving relevant data because of inadequately cataloguing and lack of indexing with a standardized terminology. Given the commonalities between the HealthData.gov and MEDLINE metadata, Medical Subject Headings (MeSH) may offer an indexing solution, but there needs to be a formal evaluation of the efficacy of MeSH for covering the dataset concepts. The purpose of this study was to determine if MeSH adequately covers the HealthData.gov concepts. The noun and noun phrases from the HealthData.gov metadata were extracted and mapped to MeSH using MetaMap. The frequency of no exact, partical and no matches with MeSH terms were determined. The results of this study revealed that about 70% of the HealthData.gov concepts partially or exactly matched MeSH terms. Therefore, MeSH may be a favorable terminology for indexing the HealthData.gov datasets.

  16. User Manual for the PROTEUS Mesh Tools

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Micheal A. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, Emily R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-06-01

    This report describes the various mesh tools that are provided with the PROTEUS code giving both descriptions of the input and output. In many cases the examples are provided with a regression test of the mesh tools. The most important mesh tools for any user to consider using are the MT_MeshToMesh.x and the MT_RadialLattice.x codes. The former allows the conversion between most mesh types handled by PROTEUS while the second allows the merging of multiple (assembly) meshes into a radial structured grid. Note that the mesh generation process is recursive in nature and that each input specific for a given mesh tool (such as .axial or .merge) can be used as “mesh” input for any of the mesh tools discussed in this manual.

  17. Mesh Algorithms for PDE with Sieve I: Mesh Distribution

    Directory of Open Access Journals (Sweden)

    Matthew G. Knepley

    2009-01-01

    Full Text Available We have developed a new programming framework, called Sieve, to support parallel numerical partial differential equation(s (PDE algorithms operating over distributed meshes. We have also developed a reference implementation of Sieve in C++ as a library of generic algorithms operating on distributed containers conforming to the Sieve interface. Sieve makes instances of the incidence relation, or arrows, the conceptual first-class objects represented in the containers. Further, generic algorithms acting on this arrow container are systematically used to provide natural geometric operations on the topology and also, through duality, on the data. Finally, coverings and duality are used to encode not only individual meshes, but all types of hierarchies underlying PDE data structures, including multigrid and mesh partitions. In order to demonstrate the usefulness of the framework, we show how the mesh partition data can be represented and manipulated using the same fundamental mechanisms used to represent meshes. We present the complete description of an algorithm to encode a mesh partition and then distribute a mesh, which is independent of the mesh dimension, element shape, or embedding. Moreover, data associated with the mesh can be similarly distributed with exactly the same algorithm. The use of a high level of abstraction within the Sieve leads to several benefits in terms of code reuse, simplicity, and extensibility. We discuss these benefits and compare our approach to other existing mesh libraries.

  18. An Adaptive Mesh Algorithm: Mesh Structure and Generation

    Energy Technology Data Exchange (ETDEWEB)

    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. The type of AMR described herein is a locally refi ned AMR. In the algorithm described, at any point in physical space only one zone exists at whatever level of mesh that is appropriate for that physical location. The dynamic creation of a locally refi ned computational mesh is made practical by a judicious selection of mesh rules. With these rules the mesh is evolved via a mesh potential designed to concentrate the nest mesh in regions where the physics is modally dense, and coarsen zones in regions where the physics is modally

  19. Mesh Algorithms for PDE with Sieve I: Mesh Distribution

    CERN Document Server

    Knepley, Matthew G

    2009-01-01

    We have developed a new programming framework, called Sieve, to support parallel numerical PDE algorithms operating over distributed meshes. We have also developed a reference implementation of Sieve in C++ as a library of generic algorithms operating on distributed containers conforming to the Sieve interface. Sieve makes instances of the incidence relation, or \\emph{arrows}, the conceptual first-class objects represented in the containers. Further, generic algorithms acting on this arrow container are systematically used to provide natural geometric operations on the topology and also, through duality, on the data. Finally, coverings and duality are used to encode not only individual meshes, but all types of hierarchies underlying PDE data structures, including multigrid and mesh partitions. In order to demonstrate the usefulness of the framework, we show how the mesh partition data can be represented and manipulated using the same fundamental mechanisms used to represent meshes. We present the complete des...

  20. Risk Factors for Mesh Exposure after Transvaginal Mesh Surgery

    Institute of Scientific and Technical Information of China (English)

    Ke Niu; Yong-Xian Lu; Wen-Jie Shen; Ying-Hui Zhang; Wen-Ying Wang

    2016-01-01

    Background:Mesh exposure after surgery continues to be a clinical challenge for urogynecological surgeons.The purpose of this study was to explore the risk factors for polypropylene (PP) mesh exposure after transvaginal mesh (TVM) surgery.Methods:This study included 195 patients with advanced pelvic organ prolapse (POP),who underwent TVM from January 2004to December 2012 at the First Affiliated Hospital of Chinese PLA General Hospital.Clinical data were evaluated including patient's demography,TVM type,concomitant procedures,operation time,blood loss,postoperative morbidity,and mesh exposure.Mesh exposure was identified through postoperative vaginal examination.Statistical analysis was performed to identify risk factors for mesh exposure.Results:Two-hundred and nine transvaginal PP meshes were placed,including 194 in the anterior wall and 15 in the posterior wall.Concomitant tension-free vaginal tape was performed in 61 cases.The mean follow-up time was 35.1 ± 23.6 months.PP mesh exposure was identified in 32 cases (16.4%),with 31 in the anterior wall and 1 in the posterior wall.Significant difference was found in operating time and concomitant procedures between exposed and nonexposed groups (F =7.443,P =0.007;F =4.307,P =0.039,respectively).Binary logistic regression revealed that the number of concomitant procedures and operation time were risk factors for mesh exposure (P =0.001,P =0.043).Conclusion:Concomitant procedures and increased operating time increase the risk for postoperative mesh exposure in patients undergoing TVM surgery for POP.

  1. Hernia Surgical Mesh Implants

    Science.gov (United States)

    ... Prosthetics Hernia Surgical Mesh Implants Hernia Surgical Mesh Implants Share Tweet Linkedin Pin it More sharing options ... majority of tissue used to produce these mesh implants are from a pig (porcine) or cow (bovine) ...

  2. Urogynecologic Surgical Mesh Implants

    Science.gov (United States)

    ... Prosthetics Urogynecologic Surgical Mesh Implants Urogynecologic Surgical Mesh Implants Share Tweet Linkedin Pin it More sharing options ... majority of tissue used to produce these mesh implants are from a pig (porcine) or cow (bovine). ...

  3. Spherical geodesic mesh generation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Measurement campaign on connectivity of mesh networks formed by mobile devices

    DEFF Research Database (Denmark)

    Pietrarca, Beatrice; Sasso, Giovanni; Perrucci, Gian Paolo

    2007-01-01

    networks. The results represent typically worst-case situations, as more and more people tend to switch off their short-range technology due to the battery consumption and the possible attacks. We explore typical public places like airports, convention centers, shopping malls and bars and extract from them...... some statistics of the size of the mesh network and type of constituent nodes. This information is essential for analyzing and devising cooperative strategies among the terminals of mesh networks in different scenarios....

  5. User Manual for the PROTEUS Mesh Tools

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Micheal A. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, Emily R [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-19

    PROTEUS is built around a finite element representation of the geometry for visualization. In addition, the PROTEUS-SN solver was built to solve the even-parity transport equation on a finite element mesh provided as input. Similarly, PROTEUS-MOC and PROTEUS-NEMO were built to apply the method of characteristics on unstructured finite element meshes. Given the complexity of real world problems, experience has shown that using commercial mesh generator to create rather simple input geometries is overly complex and slow. As a consequence, significant effort has been put into place to create multiple codes that help assist in the mesh generation and manipulation. There are three input means to create a mesh in PROTEUS: UFMESH, GRID, and NEMESH. At present, the UFMESH is a simple way to generate two-dimensional Cartesian and hexagonal fuel assembly geometries. The UFmesh input allows for simple assembly mesh generation while the GRID input allows the generation of Cartesian, hexagonal, and regular triangular structured grid geometry options. The NEMESH is a way for the user to create their own mesh or convert another mesh file format into a PROTEUS input format. Given that one has an input mesh format acceptable for PROTEUS, we have constructed several tools which allow further mesh and geometry construction (i.e. mesh extrusion and merging). This report describes the various mesh tools that are provided with the PROTEUS code giving both descriptions of the input and output. In many cases the examples are provided with a regression test of the mesh tools. The most important mesh tools for any user to consider using are the MT_MeshToMesh.x and the MT_RadialLattice.x codes. The former allows the conversion between most mesh types handled by PROTEUS while the second allows the merging of multiple (assembly) meshes into a radial structured grid. Note that the mesh generation process is recursive in nature and that each input specific for a given mesh tool (such as .axial

  6. Mesh complications in female pelvic floor reconstructive surgery and their management: A systematic review

    Directory of Open Access Journals (Sweden)

    Hemendra N Shah

    2012-01-01

    Full Text Available We reviewed the incidence, predisposing factors, presentation and management of complications related to the use of synthetic mesh in the management of stress urinary incontinence and pelvic organ prolapse repair. Immediate complications, such as bleeding, hematoma, injury to adjacent organs during placement of mesh and complication of voiding dysfunction are not discussed in this review, since they are primarily related to technique. A PubMed search of related articles published in English was done from April 2008 to March 2011. Key words used were urinary incontinence, mesh, complications, midurethral sling, anterior prolapse, anterior vaginal repair, pelvic organ prolapse, transvaginal mesh, vault prolapse, midurethral slings, female stress urinary incontinence, mesh erosion, vaginal mesh complications, and posterior vaginal wall prolapse. Since there were very few articles dealing with the management of mesh-related complications in the period covered in the search we extended the search from January 2005 onwards. Articles were selected to fit the scope of the topic. In addition, landmark publications and Manufacturer and User Facility Device Experience (MAUDE data (FDA website were included on the present topic. A total of 170 articles were identified. The use of synthetic mesh in sub-urethral sling procedures is now considered the standard for the surgical management of stress urinary incontinence. Synthetic mesh is being increasingly used in the management of pelvic organ prolapse. While the incidence of extrusion and erosion with mid-urethral sling is low, the extrusion rate in prolapse repair is somewhat higher and the use in posterior compartment remains controversial. When used through the abdominal approach the extrusion and erosion rates are lower. The management of mesh complication is an individualized approach. The choice of the technique should be based on the type of mesh complication, location of the extrusion and/or erosion

  7. Transformational Leadership Type in Public and Private Organizations

    Directory of Open Access Journals (Sweden)

    Mihaela Rus

    2012-05-01

    Full Text Available The issue concerning leadership is a very complex one, that is why taking into the account theplurity of styles already existent many times it was asked the questions: „What type of leadership isnecessary?”. By asking this question, we are thinking of a person responsible with organizing or coordinatingwork or the ones hired to do this, to think of what people want, to solve the management problems in group.This study is intended as a comparison of the two types of leadership (transformational vs. transactional interms of employee performance in public and private organizations. To measure performance and chose twoindicators: satisfaction and productivity. This study falls into the category of research studies the type ofdriving through subordinates with both theoretical and practical implications. The efficiency of this type ofleadership has been demonstrated by studies especially in the political and military and very few studies havebeen made in industrial .Type of transformational leadership is better than transactional perceived astransformational leaders are closer to the needs of employees and continuously investigate these necessities.This paper presents a practical validity as advising managers to develop a transformational type of leadership,both public and private organizations, leads to better performance. Also open new avenues of research,among which we can mention: study the impact of organizational culture on the adoption of transformationaltype vs transactional type; decision-making mechanisms in the type of transformational leadership; initiatetraining programs to develop a transformational type of leadership.

  8. Tensile Behaviour of Welded Wire Mesh and Hexagonal Metal Mesh for Ferrocement Application

    Science.gov (United States)

    Tanawade, A. G.; Modhera, C. D.

    2017-08-01

    Tension tests were conducted on welded mesh and hexagonal Metal mesh. Welded Mesh is available in the market in different sizes. The two types are analysed viz. Ø 2.3 mm and Ø 2.7 mm welded mesh, having opening size 31.75 mm × 31.75 mm and 25.4 mm × 25.4 mm respectively. Tensile strength test was performed on samples of welded mesh in three different orientations namely 0°, 30° and 45° degrees with the loading axis and hexagonal Metal mesh of Ø 0.7 mm, having opening 19.05 × 19.05 mm. Experimental tests were conducted on samples of these meshes. The objective of this study was to investigate the behaviour of the welded mesh and hexagonal Metal mesh. The result shows that the tension load carrying capacity of welded mesh of Ø 2.7 mm of 0° orientation is good as compared to Ø2.3 mm mesh and ductility of hexagonal Metal mesh is good in behaviour.

  9. The moving mesh code Shadowfax

    CERN Document Server

    Vandenbroucke, Bert

    2016-01-01

    We introduce the moving mesh code Shadowfax, which can be used to evolve a mixture of gas, subject to the laws of hydrodynamics and gravity, and any collisionless fluid only subject to gravity, such as cold dark matter or stars. The code is written in C++ and its source code is made available to the scientific community under the GNU Affero General Public License. We outline the algorithm and the design of our implementation, and demonstrate its validity through the results of a set of basic test problems, which are also part of the public version. We also compare Shadowfax with a number of other publicly available codes using different hydrodynamical integration schemes, illustrating the advantages and disadvantages of the moving mesh technique.

  10. The moving mesh code SHADOWFAX

    Science.gov (United States)

    Vandenbroucke, B.; De Rijcke, S.

    2016-07-01

    We introduce the moving mesh code SHADOWFAX, which can be used to evolve a mixture of gas, subject to the laws of hydrodynamics and gravity, and any collisionless fluid only subject to gravity, such as cold dark matter or stars. The code is written in C++ and its source code is made available to the scientific community under the GNU Affero General Public Licence. We outline the algorithm and the design of our implementation, and demonstrate its validity through the results of a set of basic test problems, which are also part of the public version. We also compare SHADOWFAX with a number of other publicly available codes using different hydrodynamical integration schemes, illustrating the advantages and disadvantages of the moving mesh technique.

  11. Mesh network simulation

    OpenAIRE

    Pei Ping; YURY N. PETRENKO

    2015-01-01

    A Mesh network simulation framework which provides a powerful and concise modeling chain for a network structure will be introduce in this report. Mesh networks has a special topologic structure. The paper investigates a message transfer in wireless mesh network simulation and how does it works in cellular network simulation. Finally the experimental result gave us the information that mesh networks have different principle in transmission way with cellular networks in transmission, and multi...

  12. Mesh generation in archipelagos

    NARCIS (Netherlands)

    Terwisscha van Scheltinga, A.; Myers, P.G.; Pietrzak, J.D.

    2012-01-01

    A new mesh size field is presented that is specifically designed for efficient meshing of highly irregular oceanic domains: archipelagos. The new approach is based on the standard mesh size field that uses the proximity to the nearest coastline. Here, the proximities to the two nearest coastlines

  13. Connectivity editing for quadrilateral meshes

    KAUST Repository

    Peng, Chihan

    2011-12-12

    We propose new connectivity editing operations for quadrilateral meshes with the unique ability to explicitly control the location, orientation, type, and number of the irregular vertices (valence not equal to four) in the mesh while preserving sharp edges. We provide theoretical analysis on what editing operations are possible and impossible and introduce three fundamental operations to move and re-orient a pair of irregular vertices. We argue that our editing operations are fundamental, because they only change the quad mesh in the smallest possible region and involve the fewest irregular vertices (i.e., two). The irregular vertex movement operations are supplemented by operations for the splitting, merging, canceling, and aligning of irregular vertices. We explain how the proposed highlevel operations are realized through graph-level editing operations such as quad collapses, edge flips, and edge splits. The utility of these mesh editing operations are demonstrated by improving the connectivity of quad meshes generated from state-of-art quadrangulation techniques. © 2011 ACM.

  14. Connectivity editing for quadrilateral meshes

    KAUST Repository

    Peng, Chihan

    2011-12-01

    We propose new connectivity editing operations for quadrilateral meshes with the unique ability to explicitly control the location, orientation, type, and number of the irregular vertices (valence not equal to four) in the mesh while preserving sharp edges. We provide theoretical analysis on what editing operations are possible and impossible and introduce three fundamental operations to move and re-orient a pair of irregular vertices. We argue that our editing operations are fundamental, because they only change the quad mesh in the smallest possible region and involve the fewest irregular vertices (i.e., two). The irregular vertex movement operations are supplemented by operations for the splitting, merging, canceling, and aligning of irregular vertices. We explain how the proposed high-level operations are realized through graph-level editing operations such as quad collapses, edge flips, and edge splits. The utility of these mesh editing operations are demonstrated by improving the connectivity of quad meshes generated from state-of-art quadrangulation techniques.

  15. Finite element mesh generation

    CERN Document Server

    Lo, Daniel SH

    2014-01-01

    Highlights the Progression of Meshing Technologies and Their ApplicationsFinite Element Mesh Generation provides a concise and comprehensive guide to the application of finite element mesh generation over 2D domains, curved surfaces, and 3D space. Organised according to the geometry and dimension of the problem domains, it develops from the basic meshing algorithms to the most advanced schemes to deal with problems with specific requirements such as boundary conformity, adaptive and anisotropic elements, shape qualities, and mesh optimization. It sets out the fundamentals of popular techniques

  16. The generation of hexahedral meshes for assembly geometries: A survey

    Energy Technology Data Exchange (ETDEWEB)

    TAUTGES,TIMOTHY J.

    2000-02-14

    The finite element method is being used today to model component assemblies in a wide variety of application areas, including structural mechanics, fluid simulations, and others. Generating hexahedral meshes for these assemblies usually requires the use of geometry decomposition, with different meshing algorithms applied to different regions. While the primary motivation for this approach remains the lack of an automatic, reliable all-hexahedral meshing algorithm, requirements in mesh quality and mesh configuration for typical analyses are also factors. For these reasons, this approach is also sometimes required when producing other types of unstructured meshes. This paper will review progress to date in automating many parts of the hex meshing process, which has halved the time to produce all-hex meshes for large assemblies. Particular issues which have been exposed due to this progress will also be discussed, along with their applicability to the general unstructured meshing problem.

  17. MOAB : a mesh-oriented database.

    Energy Technology Data Exchange (ETDEWEB)

    Tautges, Timothy James; Ernst, Corey; Stimpson, Clint; Meyers, Ray J.; Merkley, Karl

    2004-04-01

    A finite element mesh is used to decompose a continuous domain into a discretized representation. The finite element method solves PDEs on this mesh by modeling complex functions as a set of simple basis functions with coefficients at mesh vertices and prescribed continuity between elements. The mesh is one of the fundamental types of data linking the various tools in the FEA process (mesh generation, analysis, visualization, etc.). Thus, the representation of mesh data and operations on those data play a very important role in FEA-based simulations. MOAB is a component for representing and evaluating mesh data. MOAB can store structured and unstructured mesh, consisting of elements in the finite element 'zoo'. The functional interface to MOAB is simple yet powerful, allowing the representation of many types of metadata commonly found on the mesh. MOAB is optimized for efficiency in space and time, based on access to mesh in chunks rather than through individual entities, while also versatile enough to support individual entity access. The MOAB data model consists of a mesh interface instance, mesh entities (vertices and elements), sets, and tags. Entities are addressed through handles rather than pointers, to allow the underlying representation of an entity to change without changing the handle to that entity. Sets are arbitrary groupings of mesh entities and other sets. Sets also support parent/child relationships as a relation distinct from sets containing other sets. The directed-graph provided by set parent/child relationships is useful for modeling topological relations from a geometric model or other metadata. Tags are named data which can be assigned to the mesh as a whole, individual entities, or sets. Tags are a mechanism for attaching data to individual entities and sets are a mechanism for describing relations between entities; the combination of these two mechanisms is a powerful yet simple interface for representing metadata or application

  18. INGUINAL HERNIA SURGERY UNDER LOCAL ANAESTHESIA, AS DAY CARE SURGERY AND COMPARISON AMONG THREE GROUP OF PATIENTS CLASSIFIED ACCORDING TO TYPE OF MESH USED

    Directory of Open Access Journals (Sweden)

    Arvind

    2015-06-01

    Full Text Available BACKGROUND: Inguinal hernia repair is one of the most commonly performed operations worldwide . This study was done to evaluate , local anesthesia as choice of procedure for inguinal hernia as day care surgery including both regular & comorbidity associated patients , to know which mesh is suitable smallpore ( H eavy weight or largepore ( L igh t weight and to know if use of absorbable suture is better than non - absorbable suture for fixation of mesh. METHODS: We prospectively studied 69 patients with a primary unilateral inguinal hernia. The study group was randomized to Lichtenstein repair afte r taking full informed consent. Pain was assessed by visual analogue scale , Quality of life was assessed by responses to a health questionnaire administered to post - operative patients . RESULTS: The highest contraction rate was found in polypropylene small pore mesh (28.76% , followed by polypropylene large pore mesh (23.9% and the least contraction seen in knitted composite mesh (17.2%. Quality of life was assessed at 1 month and 3 month have shown significant difference among three groups. CONCLUSION: Mos t of the inguinal hernia surgery can be carried out smoothly in local anesthesia , as day care procedure. It is choice of procedure also in patients with comorbidity. Use of absorbable suture for Lichtenstein hernia repair did not affect recurrence rate. Qu ality of life is better with knitted composite group , than pp large pore group , than Polypropylene small pore mesh.

  19. ON MOBILE MESH NETWORKS

    OpenAIRE

    2015-01-01

    With the advances in mobile computing technologies and the growth of the Net, mobile mesh networks are going through a set of important evolutionary steps. In this paper, we survey architectural aspects of mobile mesh networks and their use cases and deployment models. Also, we survey challenging areas of mobile mesh networks and describe our vision of promising mobile services. This paper presents a basic introductory material for Masters of Open Information Technologies Lab, interested in m...

  20. Experimental Study on the Velocity and Efficiency Characteristics of a Serial Staged Needle Array-Mesh Type EHD Gas Pump%Experimental Study on the Velocity and Efficiency Characteristics of a Serial Staged Needle Array-Mesh Type EHD Gas Pump

    Institute of Scientific and Technical Information of China (English)

    邱炜; 夏令志; 杨兰均; 张乔根; 肖磊; 陈立

    2011-01-01

    The ionic wind has good application prospects in the fields of air flow control and heat transfer enhancement. The key for successful applications is how to improve the velocity and how to increase the active area of the ionic wind. This paper designed a needle array-mesh type electrohydrodynamic (EHD) gas pump. The use of needle array electrode where corona discharge started simultaneously could enlarge the active area. The velocity of the ionic wind could increase by placing several single-stage ionic wind generators in series appropriately, called as serial staged generator. The maximum average flow velocity of 16.1 m/s and volumetric flow of 303.5 L/min were achieved at the outlet of a 25-stage gas pump and the conversion efficiency was approximately 2.2%.

  1. Delaunay mesh generation

    CERN Document Server

    Cheng, Siu-Wing; Shewchuk, Jonathan

    2013-01-01

    Written by authors at the forefront of modern algorithms research, Delaunay Mesh Generation demonstrates the power and versatility of Delaunay meshers in tackling complex geometric domains ranging from polyhedra with internal boundaries to piecewise smooth surfaces. Covering both volume and surface meshes, the authors fully explain how and why these meshing algorithms work.The book is one of the first to integrate a vast amount of cutting-edge material on Delaunay triangulations. It begins with introducing the problem of mesh generation and describing algorithms for constructing Delaunay trian

  2. 2D Mesh Manipulation

    Science.gov (United States)

    2011-11-01

    triangles in two dimensions and tetrahedra ( tets ) in three dimensions. There are many other ways to discretize a region using unstructured meshes, but this...The boundary points associated with the airfoil surface were moved, but all of the interior points remained stationary , which resulted in a mesh

  3. An Adaptive Mesh Algorithm: Mapping the Mesh Variables

    Energy Technology Data Exchange (ETDEWEB)

    Scannapieco, Anthony J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-25

    Both thermodynamic and kinematic variables must be mapped. The kinematic variables are defined on a separate kinematic mesh; it is the duel mesh to the thermodynamic mesh. The map of the kinematic variables is done by calculating the contributions of kinematic variables on the old thermodynamic mesh, mapping the kinematic variable contributions onto the new thermodynamic mesh and then synthesizing the mapped kinematic variables on the new kinematic mesh. In this document the map of the thermodynamic variables will be described.

  4. Wireless mesh networks

    CERN Document Server

    Held, Gilbert

    2005-01-01

    Wireless mesh networking is a new technology that has the potential to revolutionize how we access the Internet and communicate with co-workers and friends. Wireless Mesh Networks examines the concept and explores its advantages over existing technologies. This book explores existing and future applications, and examines how some of the networking protocols operate.The text offers a detailed analysis of the significant problems affecting wireless mesh networking, including network scale issues, security, and radio frequency interference, and suggests actual and potential solutions for each pro

  5. MeSH Now: automatic MeSH indexing at PubMed scale via learning to rank.

    Science.gov (United States)

    Mao, Yuqing; Lu, Zhiyong

    2017-04-17

    MeSH indexing is the task of assigning relevant MeSH terms based on a manual reading of scholarly publications by human indexers. The task is highly important for improving literature retrieval and many other scientific investigations in biomedical research. Unfortunately, given its manual nature, the process of MeSH indexing is both time-consuming (new articles are not immediately indexed until 2 or 3 months later) and costly (approximately ten dollars per article). In response, automatic indexing by computers has been previously proposed and attempted but remains challenging. In order to advance the state of the art in automatic MeSH indexing, a community-wide shared task called BioASQ was recently organized. We propose MeSH Now, an integrated approach that first uses multiple strategies to generate a combined list of candidate MeSH terms for a target article. Through a novel learning-to-rank framework, MeSH Now then ranks the list of candidate terms based on their relevance to the target article. Finally, MeSH Now selects the highest-ranked MeSH terms via a post-processing module. We assessed MeSH Now on two separate benchmarking datasets using traditional precision, recall and F1-score metrics. In both evaluations, MeSH Now consistently achieved over 0.60 in F-score, ranging from 0.610 to 0.612. Furthermore, additional experiments show that MeSH Now can be optimized by parallel computing in order to process MEDLINE documents on a large scale. We conclude that MeSH Now is a robust approach with state-of-the-art performance for automatic MeSH indexing and that MeSH Now is capable of processing PubMed scale documents within a reasonable time frame. http://www.ncbi.nlm.nih.gov/CBBresearch/Lu/Demo/MeSHNow/ .

  6. Confined helium on Lagrange meshes

    CERN Document Server

    Baye, Daniel

    2015-01-01

    The Lagrange-mesh method has the simplicity of a calculation on a mesh and can have the accuracy of a variational method. It is applied to the study of a confined helium atom. Two types of confinement are considered. Soft confinements by potentials are studied in perimetric coordinates. Hard confinement in impenetrable spherical cavities is studied in a system of rescaled perimetric coordinates varying in [0,1] intervals. Energies and mean values of the distances between electrons and between an electron and the helium nucleus are calculated. A high accuracy of 11 to 15 significant figures is obtained with small computing times. Pressures acting on the confined atom are also computed. For sphere radii smaller than 1, their relative accuracies are better than $10^{-10}$. For larger radii up to 10, they progressively decrease to $10^{-3}$, still improving the best literature results.

  7. Mesh implants: An overview of crucial mesh parameters

    Institute of Scientific and Technical Information of China (English)

    Lei-Ming; Zhu; Philipp; Schuster; Uwe; Klinge

    2015-01-01

    Hernia repair is one of the most frequently performed surgical interventions that use mesh implants. This article evaluates crucial mesh parameters to facilitate selection of the most appropriate mesh implant, considering raw materials, mesh composition, structure parameters and mechanical parameters. A literature review was performed using the Pub Med database. The most important mesh parameters in the selection of a mesh implant are the raw material, structural parameters and mechanical parameters, which should match the physiological conditions. The structural parameters, especially the porosity, are the most important predictors of the biocompatibility performance of synthetic meshes. Meshes with large pores exhibit less inflammatory infiltrate, connective tissue and scar bridging, which allows increased soft tissue ingrowth. The raw material and combination of raw materials of the used mesh, including potential coatings and textile design, strongly impact the inflammatory reaction to the mesh. Synthetic meshes made from innovative polymers combined with surface coating have been demonstrated to exhibit advantageous behavior in specialized fields. Monofilament, largepore synthetic meshes exhibit advantages. The value of mesh classification based on mesh weight seems to be overestimated. Mechanical properties of meshes, such as anisotropy/isotropy, elasticity and tensile strength, are crucial parameters for predicting mesh performance after implantation.

  8. CVT封闭的2K-H型差动轮系啮合效率分析%Meshing efficiency analysis of 2K-H type differential gear train closed by CVT

    Institute of Scientific and Technical Information of China (English)

    黄云峰

    2012-01-01

    For the problem that power circulation and low efficiency easily occur in closed Continuously Variable Transmission (CVT) ,the input-coupled CVT drive system was taken as the object of study, the fundamental structure and working principle of the input-coupled CVT drive system were briefly introduced.Without loss of energy in the input-coupled CVT drive system,the sufficient condition for the input-coupled CVT drive system to realize power split was deduced in detail.Next,under the sufficient condition, the meshing efficiency expression for the 2K-H type differential gear train acting as power confluence in the input-coupled CVT drive system was simplified, and the factors related to meshing efficiency of the 2K-H type differential gear train such as the structural parameter and motion state of input components were obtained.The conditions for meshing efficiency of the 2K-H type differential gear train to be maximized were demonstrated.Finally ,the conditions of maximum meshing efficiency for the 2K-H type differential gear train were verified by analyzing the examples.The results show that the conditions of maximum meshing efficiency ensure the highest meshing efficiency of the 2K-H type differential gear train from thedesign point of view.The idea of maximizing the meshing efficiency analysis of the 2K-H type differentialgear train is an effective design approach.%针对封闭式无级变速器内部容易发生功率循环而造成效率降低的问题,以输入耦合CVT(Continuously Variable Transmission)传动系统为研究对象,简单地介绍了其基本结构及工作原理,在无能量损失的理想状态下详细推导了该传动系统实现功率分流的充分条件.其次,在该充分条件下简化了输入耦合CVT传动系统中起汇流作用的2K-H型差动轮系啮合效率表达式,得到了影响啮合效率的输入构件结构参数和运动状态等因素,求证了其获得最大值的条件.最后,通过实例验证了所得到的2K-H

  9. Polygon mesh processing

    CERN Document Server

    Botsch, Mario; Pauly, Mark; Alliez, Pierre; Levy, Bruno

    2010-01-01

    Geometry processing, or mesh processing, is a fast-growing area of research that uses concepts from applied mathematics, computer science, and engineering to design efficient algorithms for the acquisition, reconstruction, analysis, manipulation, simulation, and transmission of complex 3D models. Applications of geometry processing algorithms already cover a wide range of areas from multimedia, entertainment, and classical computer-aided design, to biomedical computing, reverse engineering, and scientific computing. Over the last several years, triangle meshes have become increasingly popular,

  10. Geometrically Consistent Mesh Modification

    KAUST Repository

    Bonito, A.

    2010-01-01

    A new paradigm of adaptivity is to execute refinement, coarsening, and smoothing of meshes on manifolds with incomplete information about their geometry and yet preserve position and curvature accuracy. We refer to this collectively as geometrically consistent (GC) mesh modification. We discuss the concept of discrete GC, show the failure of naive approaches, and propose and analyze a simple algorithm that is GC and accuracy preserving. © 2010 Society for Industrial and Applied Mathematics.

  11. Split Bregman's algorithm for three-dimensional mesh segmentation

    Science.gov (United States)

    Habiba, Nabi; Ali, Douik

    2016-05-01

    Variational methods have attracted a lot of attention in the literature, especially for image and mesh segmentation. The methods aim at minimizing the energy to optimize both edge and region detections. We propose a spectral mesh decomposition algorithm to obtain disjoint but meaningful regions of an input mesh. The related optimization problem is nonconvex, and it is very difficult to find a good approximation or global optimum, which represents a challenge in computer vision. We propose an alternating split Bregman algorithm for mesh segmentation, where we extended the image-dedicated model to a three-dimensional (3-D) mesh one. By applying our scheme to 3-D mesh segmentation, we obtain fast solvers that can outperform various conventional ones, such as graph-cut and primal dual methods. A consistent evaluation of the proposed method on various public domain 3-D databases for different metrics is elaborated, and a comparison with the state-of-the-art is performed.

  12. Investigation of Mesh Choosing Parameters in Screen Printing System

    Directory of Open Access Journals (Sweden)

    Ahmet AKGÜL

    2012-05-01

    Full Text Available The mesh, which is made by weaving of natural silk, plastic, or metal fibers, is basic material for screen-printing. Image is created on stretched on a frame in screen-printing. Mesh should be selected correctly for a high quality printing. Therefore, substrates, types of print job and mesh parameters have importance. Need to know more about to mesh, yarn type, yarn thickness, frequency of weaving, stretching tension, the kind of weaving, etc. In this study, for a high quality screen-printing, mesh variables examined in detail and optimum conditions indicated, with the aim of increase productivity, minimize to losses time, material and labor. As a result, this information’s for obtaining a high quality printing with screen-printing system have importance as a guide. Also resolution of the image, amount of print run and viscosity of the printing ink, factors affecting the selection of mesh.

  13. Hybrid Surface Mesh Adaptation for Climate Modeling

    Institute of Scientific and Technical Information of China (English)

    Ahmed Khamayseh; Valmor de Almeida; Glen Hansen

    2008-01-01

    Solution-driven mesh adaptation is becoming quite popular for spatial error control in the numerical simulation of complex computational physics applications, such as climate modeling. Typically, spatial adaptation is achieved by element subdivision (h adaptation) with a primary goal of resolving the local length scales of interest. A second, lesspopular method of spatial adaptivity is called "mesh motion" (r adaptation); the smooth repositioning of mesh node points aimed at resizing existing elements to capture the local length scales. This paper proposes an adaptation method based on a combination of both element subdivision and node point repositioning (rh adaptation). By combining these two methods using the notion of a mobility function, the proposed approach seeks to increase the flexibility and extensibility of mesh motion algorithms while providing a somewhat smoother transition between refined regions than is pro-duced by element subdivision alone. Further, in an attempt to support the requirements of a very general class of climate simulation applications, the proposed method is de-signed to accommodate unstructured, polygonal mesh topologies in addition to the most popular mesh types.

  14. Study on Mesh Roller-type Unginned Cotton Film Remnant Separator%网状滚筒式籽棉残膜分离机分离效果研究

    Institute of Scientific and Technical Information of China (English)

    郭文松; 张若宇; 坎杂; 安红磊; 郭淑霞; 从腾达

    2011-01-01

    [Objective]The aim was to study the relationship between influence factors and separation effect of unginned cotton and film remnant. [ Method] With the dragout ratio of unginned cotton, separate ratio of film remnant as response indicators, rotation speed of small and big mesh-roller, inlet wind speed of slop channel as influence factors, the single factor experiment was designed. [ Result] The results showed that the rotation speed of small mesh-roller, inlet wind speed of slop channel and angle of slop channel influenced response indices significantly (P <0.01) ;rotation speed of big mesh-roller, included angle of mesh-roller influenced dragout ratio of unginned cotton significantly(P <0.01). [Conclusion] The selected factors had effects on two response indicators of mesh roller-type unginned cotton film remnant separator.%[目的]研究影响网状滚筒式籽棉残膜分离机的因素对实现残膜与籽棉的分离效果的影响.[方法]以残膜分离率和籽棉带出比为响应指标,选取大、小网状滚筒转速,斜筒入口风速等为影响因素,对网状滚筒式籽棉残膜分离机进行了单因素试验.[结果]小网状滚筒转速、斜桶入口风速、斜桶角度对响应指标影响P<0.01,影响均显著;大网状滚筒转速、滚筒夹角对籽棉带出比影响P<0.01,影响显著.[结论]选取的影响因素均对网状滚筒式籽棉残膜分离机的2个响应指标有影响.

  15. Biomechanical analyses of prosthetic mesh repair in a hiatal hernia model.

    Science.gov (United States)

    Alizai, Patrick Hamid; Schmid, Sofie; Otto, Jens; Klink, Christian Daniel; Roeth, Anjali; Nolting, Jochen; Neumann, Ulf Peter; Klinge, Uwe

    2014-10-01

    Recurrence rate of hiatal hernia can be reduced with prosthetic mesh repair; however, type and shape of the mesh are still a matter of controversy. The purpose of this study was to investigate the biomechanical properties of four conventional meshes: pure polypropylene mesh (PP-P), polypropylene/poliglecaprone mesh (PP-U), polyvinylidenefluoride/polypropylene mesh (PVDF-I), and pure polyvinylidenefluoride mesh (PVDF-S). Meshes were tested either in warp direction (parallel to production direction) or perpendicular to the warp direction. A Zwick testing machine was used to measure elasticity and effective porosity of the textile probes. Stretching of the meshes in warp direction required forces that were up to 85-fold higher than the same elongation in perpendicular direction. Stretch stress led to loss of effective porosity in most meshes, except for PVDF-S. Biomechanical impact of the mesh was additionally evaluated in a hiatal hernia model. The different meshes were used either as rectangular patches or as circular meshes. Circular meshes led to a significant reinforcement of the hiatus, largely unaffected by the orientation of the warp fibers. In contrast, rectangular meshes provided a significant reinforcement only when warp fibers ran perpendicular to the crura. Anisotropic elasticity of prosthetic meshes should therefore be considered in hiatal closure with rectangular patches.

  16. Documentation for MeshKit - Reactor Geometry (&mesh) Generator

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Cosmology on a Mesh

    CERN Document Server

    Gill, S P D; Gibson, B K; Flynn, C; Ibata, R A; Lewis, G F; Gill, Stuart P.D.; Knebe, Alexander; Gibson, Brad K.; Flynn, Chris; Ibata, Rodrigo A.; Lewis, Geraint F.

    2002-01-01

    An adaptive multi grid approach to simulating the formation of structure from collisionless dark matter is described. MLAPM (Multi-Level Adaptive Particle Mesh) is one of the most efficient serial codes available on the cosmological 'market' today. As part of Swinburne University's role in the development of the Square Kilometer Array, we are implementing hydrodynamics, feedback, and radiative transfer within the MLAPM adaptive mesh, in order to simulate baryonic processes relevant to the interstellar and intergalactic media at high redshift. We will outline our progress to date in applying the existing MLAPM to a study of the decay of satellite galaxies within massive host potentials.

  18. ARC Code TI: Middleware Using Existing SSH Hosts (Mesh)

    Data.gov (United States)

    National Aeronautics and Space Administration — Mesh is a secure, lightweight grid middleware that is based on the addition of a single sign-on capability to the built-in public key authentication mechanism of SSH...

  19. Isotopic Implicit Surface Meshing

    NARCIS (Netherlands)

    Boissonnat, Jean-Daniel; Cohen-Steiner, David; Vegter, Gert

    2004-01-01

    This paper addresses the problem of piecewise linear approximation of implicit surfaces. We first give a criterion ensuring that the zero-set of a smooth function and the one of a piecewise linear approximation of it are isotopic. Then, we deduce from this criterion an implicit surface meshing algor

  20. The mesh controversy [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Joshua A. Cohn

    2016-09-01

    Full Text Available Pelvic organ prolapse and stress urinary incontinence are common conditions for which approximately 11% of women will undergo surgical intervention in their lifetime. The use of vaginal mesh for pelvic organ prolapse and stress urinary incontinence rose rapidly in the early 2000s as over 100 mesh products were introduced into the clinical armamentarium with little regulatory oversight for their use. US Food and Drug Administration Public Health Notifications in 2008 and 2011, as well as reclassification of transvaginal mesh for prolapse to class III in early 2016, were a response to debilitating complications associated with transvaginal mesh placement in many women. The midurethral sling has not been subject to the same reclassification and continues to be endorsed as the “gold standard” for surgical management of stress urinary incontinence by subspecialty societies. However, litigators have not differentiated between mesh for prolapse and mesh for incontinence. As such, all mesh, including that placed for stress urinary incontinence, faces continued controversy amidst an uncertain future. In this article, we review the background of the mesh controversy, recent developments, and the anticipated role of mesh in surgery for prolapse and stress urinary incontinence going forward.

  1. 36 CFR 1206.22 - What type of proposal is eligible for a publications grant?

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false What type of proposal is eligible for a publications grant? 1206.22 Section 1206.22 Parks, Forests, and Public Property NATIONAL... outstanding events, topics, themes, or movements of national significance in United States history....

  2. Dominant Personality Types in Public Accounting: Selection Bias or Indoctrinated?

    Science.gov (United States)

    Burton, Hughlene; Daugherty, Brian; Dickins, Denise; Schisler, Dan

    2016-01-01

    Prior studies concerning the personality type and preferences of accountants generally draw conclusions based upon the reports of either practicing accountants, or accounting students, at a single point in time. So while much is known about the personality type of accountants in general, left unexplored is the question of whether public…

  3. Advanced Automatic Hexahedral Mesh Generation from Surface Quad Meshes

    OpenAIRE

    Kremer, Michael; Bommes, David; Lim, Isaak; Kobbelt, Leif

    2013-01-01

    International audience; A purely topological approach for the generation of hexahedral meshes from quadrilateral surface meshes of genus zero has been proposed by M. Müller-Hannemann: in a first stage, the input surface mesh is reduced to a single hexahedron by successively eliminating loops from the dual graph of the quad mesh; in the second stage, the hexahedral mesh is constructed by extruding a layer of hexahedra for each dual loop from the first stage in reverse elimination order. In th...

  4. Urban revitalization and displacement: types, causes, and public policy

    Energy Technology Data Exchange (ETDEWEB)

    Feagin, J.R.

    1981-05-01

    The policy research report reviews the scholarly and print media literatures on urban revitalization. The extent of revitalization; the incumbent or occupant upgrading; gentrification (displacement of low- and moderate-income households by better-off households); gentrification and displacement from all causes; and the role of powerful actors in revitalization are discussed. Public policy dealing with land use and development in urban areas is discussed. Future research needs are indicated.

  5. Black Hole and Greyhole Attack in Wireless Mesh Network

    Directory of Open Access Journals (Sweden)

    Rupinder Kaur

    2014-10-01

    Full Text Available Security is an important need in wireless mesh networks to give safe and shared information between wireless non-static nodes. In wireless network nodes has ability to act correctly and route the packets. Wireless mesh networks unusual method of producing,keeping and sharing information ability of mobile objects to show spontaneous and cheap adjusting arrangement itself.There are different types of communication devices in technology by which performance is measured.There is a major issue which take part in network and provide security from various kinds of malicious attacks.There are various attacks such as black hole attack,wormhole attack,Greyhole attack, and evesdropping attack.Black hole and Greyhole attacks are network layer attacks that spoils the performance by falling the packets.The black hole and Grey hole are the problem of security that consider in wireless networks.Black hole and Greyhole attack is one type of way of interrupting attack and can cause large amount of damage to network.Black hole attack is act like ad-hoc network; which create network and attack on packets.In black hole attack where a false node not make correct paths in public to receiver node during the direction finding process. Theattacker achieves this attack when all the similar kinds of nodes communicate and make network to each other. It is very important to protectthe network layer from these attack which is also a great issues in wireless mesh network. Greyhole attack is very difficult to detect in wireless mesh network.In this paper,its an overview about black hole attack and grey hole in wireless mesh network and define problem statement about them. Secondly, its take study about related work in which many authors perform on these attacks and then its discuss about proposed method.Thirdly,the results are simulated carried out in OPNET simulator where black hole attack and grey hole attack shows the performance and Its analysis the throughput in network.

  6. Non-Public Schools in Durham County by Type

    Data.gov (United States)

    City and County of Durham, North Carolina — A list and the locations along with contact phone numbers of private schools within Durham County. The School Type field is either "religious" or independant....

  7. Efficient Packet Forwarding in Mesh Network

    OpenAIRE

    Soumen Kanrar

    2012-01-01

    Wireless Mesh Network (WMN) is a multi hop low cost, with easy maintenance robust network providing reliable service coverage. WMNs consist of mesh routers and mesh clients. In this architecture, while static mesh routers form the wireless backbone, mesh clients access the network through mesh routers as well as directly meshing with each other. Different from traditional wireless networks, WMN is dynamically self-organized and self-configured. In other words, the nodes in the mesh network au...

  8. Connectivity editing for quad-dominant meshes

    KAUST Repository

    Peng, Chihan

    2013-08-01

    We propose a connectivity editing framework for quad-dominant meshes. In our framework, the user can edit the mesh connectivity to control the location, type, and number of irregular vertices (with more or fewer than four neighbors) and irregular faces (non-quads). We provide a theoretical analysis of the problem, discuss what edits are possible and impossible, and describe how to implement an editing framework that realizes all possible editing operations. In the results, we show example edits and illustrate the advantages and disadvantages of different strategies for quad-dominant mesh design. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and John Wiley & Sons Ltd.

  9. Metal-mesh lithography.

    Science.gov (United States)

    Tang, Zhao; Wei, Qingshan; Wei, Alexander

    2011-12-01

    Metal-mesh lithography (MML) is a practical hybrid of microcontact printing and capillary force lithography that can be applied over millimeter-sized areas with a high level of uniformity. MML can be achieved by blotting various inks onto substrates through thin copper grids, relying on preferential wetting and capillary interactions between template and substrate for pattern replication. The resulting mesh patterns, which are inverted relative to those produced by stenciling or serigraphy, can be reproduced with low micrometer resolution. MML can be combined with other surface chemistry and lift-off methods to create functional microarrays for diverse applications, such as periodic islands of gold nanorods and patterned corrals for fibroblast cell cultures.

  10. CFD modeling and experimental verification of a single-stage coaxial Stirling-type pulse tube cryocooler without either double-inlet or multi-bypass operating at 30-35 K using mixed stainless steel mesh regenerator matrices

    Science.gov (United States)

    Dang, Haizheng; Zhao, Yibo

    2016-09-01

    This paper presents the CFD modeling and experimental verifications of a single-stage inertance tube coaxial Stirling-type pulse tube cryocooler operating at 30-35 K using mixed stainless steel mesh regenerator matrices without either double-inlet or multi-bypass. A two-dimensional axis-symmetric CFD model with the thermal non-equilibrium mode is developed to simulate the internal process, and the underlying mechanism of significantly reducing the regenerator losses with mixed matrices is discussed in detail based on the given six cases. The modeling also indicates that the combination of the given different mesh segments can be optimized to achieve the highest cooling efficiency or the largest exergy ratio, and then the verification experiments are conducted in which the satisfactory agreements between simulated and tested results are observed. The experiments achieve a no-load temperature of 27.2 K and the cooling power of 0.78 W at 35 K, or 0.29 W at 30 K, with an input electric power of 220 W and a reject temperature of 300 K.

  11. Parallel Adaptive Mesh Refinement

    Energy Technology Data Exchange (ETDEWEB)

    Diachin, L; Hornung, R; Plassmann, P; WIssink, A

    2005-03-04

    As large-scale, parallel computers have become more widely available and numerical models and algorithms have advanced, the range of physical phenomena that can be simulated has expanded dramatically. Many important science and engineering problems exhibit solutions with localized behavior where highly-detailed salient features or large gradients appear in certain regions which are separated by much larger regions where the solution is smooth. Examples include chemically-reacting flows with radiative heat transfer, high Reynolds number flows interacting with solid objects, and combustion problems where the flame front is essentially a two-dimensional sheet occupying a small part of a three-dimensional domain. Modeling such problems numerically requires approximating the governing partial differential equations on a discrete domain, or grid. Grid spacing is an important factor in determining the accuracy and cost of a computation. A fine grid may be needed to resolve key local features while a much coarser grid may suffice elsewhere. Employing a fine grid everywhere may be inefficient at best and, at worst, may make an adequately resolved simulation impractical. Moreover, the location and resolution of fine grid required for an accurate solution is a dynamic property of a problem's transient features and may not be known a priori. Adaptive mesh refinement (AMR) is a technique that can be used with both structured and unstructured meshes to adjust local grid spacing dynamically to capture solution features with an appropriate degree of resolution. Thus, computational resources can be focused where and when they are needed most to efficiently achieve an accurate solution without incurring the cost of a globally-fine grid. Figure 1.1 shows two example computations using AMR; on the left is a structured mesh calculation of a impulsively-sheared contact surface and on the right is the fuselage and volume discretization of an RAH-66 Comanche helicopter [35]. Note the

  12. Triangulated manifold meshing method preserving molecular surface topology.

    Science.gov (United States)

    Chen, Minxin; Tu, Bin; Lu, Benzhuo

    2012-09-01

    Generation of manifold mesh is an urgent issue in mathematical simulations of biomolecule using boundary element methods (BEM) or finite element method (FEM). Defects, such as not closed mesh, intersection of elements and missing of small structures, exist in surface meshes generated by most of the current meshing method. Usually the molecular surface meshes produced by existing methods need to be revised carefully by third party software to ensure the surface represents a continuous manifold before being used in a BEM and FEM calculations. Based on the trace technique proposed in our previous work, in this paper, we present an improved meshing method to avoid intersections and preserve the topology of the molecular Gaussian surface. The new method divides the whole Gaussian surface into single valued pieces along each of x, y, z directions by tracing the extreme points along the fold curves on the surface. Numerical test results show that the surface meshes produced by the new method are manifolds and preserve surface topologies. The result surface mesh can also be directly used in surface conforming volume mesh generation for FEM type simulation. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Characterization of the structure and properties of authentic and counterfeit polypropylene surgical meshes.

    Science.gov (United States)

    McDermott, M K; Isayeva, I S; Thomas, T M; Lee, A S; Lucas, A D; Witkowski, C N; Hutter, J C

    2006-04-01

    A counterfeit version of the Ethicon Prolene polypropylene mesh was distributed to hospitals and clinics and unintentionally implanted into patients undergoing tension-free hernia repair. On December 19, 2003, the Food and Drug Administration (FDA) issued a public health web notification indicating that the counterfeit mesh was not sterile or safe to use. To develop safety recommendations for patients with the counterfeit mesh implant, we compared the counterfeit's structural, physical, chemical and mechanical properties with polypropylene meshes previously cleared by FDA. The mesh fibers for all the products tested were found to have similar chemical and physical properties. The mechanical properties were directly related to the knitted structure (loop size, repeat distance, fabric tightness) and the porosity. Extracts from the counterfeit mesh passed cytotoxicity screening tests. The FDA further recommended that if the mesh had been inadvertently implanted, then those patients should be monitored as would be the practice for any patient with an implanted surgical mesh.

  14. toolkit computational mesh conceptual model.

    Energy Technology Data Exchange (ETDEWEB)

    Baur, David G.; Edwards, Harold Carter; Cochran, William K.; Williams, Alan B.; Sjaardema, Gregory D.

    2010-03-01

    The Sierra Toolkit computational mesh is a software library intended to support massively parallel multi-physics computations on dynamically changing unstructured meshes. This domain of intended use is inherently complex due to distributed memory parallelism, parallel scalability, heterogeneity of physics, heterogeneous discretization of an unstructured mesh, and runtime adaptation of the mesh. Management of this inherent complexity begins with a conceptual analysis and modeling of this domain of intended use; i.e., development of a domain model. The Sierra Toolkit computational mesh software library is designed and implemented based upon this domain model. Software developers using, maintaining, or extending the Sierra Toolkit computational mesh library must be familiar with the concepts/domain model presented in this report.

  15. Gossiping on meshes and tori

    OpenAIRE

    Sibeyn, J.; Rao, P; Juurlink, B.

    1996-01-01

    Algorithms for performing gossiping on one- and higher dimensional meshes are presented. As a routing model, we assume the practically important worm-hole routing. For one-dimensional arrays and rings, we give a novel lower bound and an asymptotically optimal gossiping algorithm for all choices of the parameters involved. For two-dimensional meshes and tori, several simple algorithms composed of one-dimensional phases are presented. For an important range of packet and mesh sizes it gives cle...

  16. Synthesized Optimization of Triangular Mesh

    Institute of Scientific and Technical Information of China (English)

    HU Wenqiang; YANG Wenyu

    2006-01-01

    Triangular mesh is often used to describe geometric object as computed model in digital manufacture, thus the mesh model with both uniform triangular shape and excellent geometric shape is expected. But in fact, the optimization of triangular shape often is contrary with that of geometric shape. In this paper, one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh model. The result mesh with uniform triangular shape and excellent topology are obtained.

  17. Surface meshing with curvature convergence

    KAUST Repository

    Li, Huibin

    2014-06-01

    Surface meshing plays a fundamental role in graphics and visualization. Many geometric processing tasks involve solving geometric PDEs on meshes. The numerical stability, convergence rates and approximation errors are largely determined by the mesh qualities. In practice, Delaunay refinement algorithms offer satisfactory solutions to high quality mesh generations. The theoretical proofs for volume based and surface based Delaunay refinement algorithms have been established, but those for conformal parameterization based ones remain wide open. This work focuses on the curvature measure convergence for the conformal parameterization based Delaunay refinement algorithms. Given a metric surface, the proposed approach triangulates its conformal uniformization domain by the planar Delaunay refinement algorithms, and produces a high quality mesh. We give explicit estimates for the Hausdorff distance, the normal deviation, and the differences in curvature measures between the surface and the mesh. In contrast to the conventional results based on volumetric Delaunay refinement, our stronger estimates are independent of the mesh structure and directly guarantee the convergence of curvature measures. Meanwhile, our result on Gaussian curvature measure is intrinsic to the Riemannian metric and independent of the embedding. In practice, our meshing algorithm is much easier to implement and much more efficient. The experimental results verified our theoretical results and demonstrated the efficiency of the meshing algorithm. © 2014 IEEE.

  18. Robust, multidimensional mesh motion based on Monge-Kantorovich equidistribution

    Energy Technology Data Exchange (ETDEWEB)

    Delzanno, G L [Los Alamos National Laboratory; Finn, J M [Los Alamos National Laboratory

    2009-01-01

    Mesh-motion (r-refinement) grid adaptivity schemes are attractive due to their potential to minimize the numerical error for a prescribed number of degrees of freedom. However, a key roadblock to a widespread deployment of the technique has been the formulation of robust, reliable mesh motion governing principles, which (1) guarantee a solution in multiple dimensions (2D and 3D), (2) avoid grid tangling (or folding of the mesh, whereby edges of a grid cell cross somewhere in the domain), and (3) can be solved effectively and efficiently. In this study, we formulate such a mesh-motion governing principle, based on volume equidistribution via Monge-Kantorovich optimization (MK). In earlier publications [1, 2], the advantages of this approach in regards to these points have been demonstrated for the time-independent case. In this study, demonstrate that Monge-Kantorovich equidistribution can in fact be used effectively in a time stepping context, and delivers an elegant solution to the otherwise pervasive problem of grid tangling in mesh motion approaches, without resorting to ad-hoc time-dependent terms (as in moving-mesh PDEs, or MMPDEs [3, 4]). We explore two distinct r-refinement implementations of MK: direct, where the current mesh relates to an initial, unchanging mesh, and sequential, where the current mesh is related to the previous one in time. We demonstrate that the direct approach is superior in regards to mesh distortion and robustness. The properties of the approach are illustrated with a paradigmatic hyperbolic PDE, the advection of a passive scalar. Imposed velocity flow fields or varying vorticity levels and flow shears are considered.

  19. Laparoscopic Total Extraperitoneal (TEP) Inguinal Hernia Repair Using 3-dimensional Mesh Without Mesh Fixation.

    Science.gov (United States)

    Aliyazicioglu, Tolga; Yalti, Tunc; Kabaoglu, Burcak

    2017-08-01

    Approximately one fifth of patients suffer from inguinal pain after laparoscopic total extraperitoneal (TEP) inguinal hernia repair. There is existing literature suggesting that the staples used to fix the mesh can cause postoperative inguinal pain. In this study, we describe our experience with laparoscopic TEP inguinal hernia surgery using 3-dimensional mesh without mesh fixation, in our institution. A total of 300 patients who had undergone laparoscopic TEP inguinal hernia repair with 3-dimensional mesh in VKV American Hospital, Istanbul from November 2006 to November 2015 were studied retrospectively. Using the hospital's electronic archive, we studied patients' selected parameters, which are demographic features (age, sex), body mass index, hernia locations and types, duration of operations, preoperative and postoperative complications, duration of hospital stays, cost of surgery, need for analgesics, time elapsed until returning to daily activities and work. A total of 300 patients underwent laparoscopic TEP hernia repair of 437 inguinal hernias from November 2006 to November 2015. Of the 185 patients, 140 were symptomatic. Mean duration of follow-up was 48 months (range, 6 to 104 mo). The mean duration of surgery was 55 minutes for bilateral hernia repair, and 38 minutes for unilateral hernia repair. The mean duration of hospital stay was 0.9 day. There was no conversion to open surgery. In none of the cases the mesh was fixated with either staples or fibrin glue. Six patients (2%) developed seroma that were treated conservatively. One patient had inguinal hernia recurrence. One patient had preperitoneal hematoma. One patient operated due to indirect right-sided hernia developed right-sided hydrocele. One patient had wound dehiscence at the umbilical port entry site. Chronic pain developed postoperatively in 1 patient. Ileus developed in 1 patient. Laparoscopic TEP inguinal repair with 3-dimensional mesh without mesh fixation can be performed as safe as

  20. A fast and robust patient specific Finite Element mesh registration technique: application to 60 clinical cases

    CERN Document Server

    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...

  1. Functionalized Nanofiber Meshes Enhance Immunosorbent Assays.

    Science.gov (United States)

    Hersey, Joseph S; Meller, Amit; Grinstaff, Mark W

    2015-12-01

    Three-dimensional substrates with high surface-to-volume ratios and subsequently large protein binding capacities are of interest for advanced immunosorbent assays utilizing integrated microfluidics and nanosensing elements. A library of bioactive and antifouling electrospun nanofiber substrates, which are composed of high-molecular-weight poly(oxanorbornene) derivatives, is described. Specifically, a set of copolymers are synthesized from three 7-oxanorbornene monomers to create a set of water insoluble copolymers with both biotin (bioactive) and triethylene glycol (TEG) (antifouling) functionality. Porous three-dimensional nanofiber meshes are electrospun from these copolymers with the ability to specifically bind streptavidin while minimizing the nonspecific binding of other proteins. Fluorescently labeled streptavidin is used to quantify the streptavidin binding capacity of each mesh type through confocal microscopy. A simplified enzyme-linked immunosorbent assay (ELISA) is presented to assess the protein binding capabilities and detection limits of these nanofiber meshes under both static conditions (26 h) and flow conditions (1 h) for a model target protein (i.e., mouse IgG) using a horseradish peroxidase (HRP) colorimetric assay. Bioactive and antifouling nanofiber meshes outperform traditional streptavidin-coated polystyrene plates under flow, validating their use in future advanced immunosorbent assays and their compatibility with microfluidic-based biosensors.

  2. S-Mesh: a Mesh-based on-chip network with separation of control and transmission

    Institute of Scientific and Technical Information of China (English)

    LIU Hao; ZOU Xue-cheng; JI Li-xin; CAI Meng; ZHANG Ke-feng

    2009-01-01

    The current network-on-chip (NoC) topology cannot predict subsequent switch node status promptly. Switch nodes have to perform various functions such as routing decision, data forwarding, packet buffering, congestion control and properties of an NoC system. Therefore, these make switch architecture far more complex. This article puts forward a separating on-chip network architecture based on Mesh (S-Mesh). S-Mesh is an on-chip network that separates routing decision flow from the switches. It consists of two types of networks: datapath network (DN) and control network (CN). The CN establishes data paths for data transferring in DN. Meanwhile, the CN also transfers instructions between different resources. This property makes switch architecture simple, and eliminates conflicts in network interface units between the resource and switch. Compared with 2D-Mesh, Torus Mesh, Fat-tree and Butterfly, the average packet latency in S-Mesh is the shortest when the packet length is more than 53 B. Compared with 2D-Mesh, the areas savings of S-Mesh is about 3%--7%, and the power dissipation is decreased by approximate 2%.

  3. Prevention of Adhesion to Prosthetic Mesh

    Science.gov (United States)

    van ’t Riet, Martijne; de Vos van Steenwijk, Peggy J.; Bonthuis, Fred; Marquet, Richard L.; Steyerberg, Ewout W.; Jeekel, Johannes; Bonjer, H. Jaap

    2003-01-01

    Objective To assess whether use of antiadhesive liquids or coatings could prevent adhesion formation to prosthetic mesh. Summary Background Data Incisional hernia repair frequently involves the use of prosthetic mesh. However, concern exists about development of adhesions between viscera and the mesh, predisposing to intestinal obstruction or enterocutaneous fistulas. Methods In 91 rats, a defect in the muscular abdominal wall was created, and mesh was fixed intraperitoneally to cover the defect. Rats were divided in five groups: polypropylene mesh only (control group), addition of Sepracoat or Icodextrin solution to polypropylene mesh, Sepramesh (polypropylene mesh with Seprafilm coating), and Parietex composite mesh (polyester mesh with collagen coating). Seven and 30 days postoperatively, adhesions were assessed and wound healing was studied by microscopy. Results Intraperitoneal placement of polypropylene mesh was followed by bowel adhesions to the mesh in 50% of the cases. A mean of 74% of the mesh surface was covered by adhesions after 7 days, and 48% after 30 days. Administration of Sepracoat or Icodextrin solution had no influence on adhesion formation. Coated meshes (Sepramesh and Parietex composite mesh) had no bowel adhesions. Sepramesh was associated with a significant reduction of the mesh surface covered by adhesions after 7 and 30 days. Infection was more prevalent with Parietex composite mesh, with concurrent increased mesh surface covered by adhesions after 30 days (78%). Conclusions Sepramesh significantly reduced mesh surface covered by adhesions and prevented bowel adhesion to the mesh. Parietex composite mesh prevented bowel adhesions as well but increased infection rates in the current model. PMID:12496539

  4. Parameterization for fitting triangular mesh

    Institute of Scientific and Technical Information of China (English)

    LIN Hongwei; WANG Guojin; LIU Ligang; BAO Hujun

    2006-01-01

    In recent years, with the development of 3D data acquisition equipments, the study on reverse engineering has become more and more important. However, the existing methods for parameterization can hardly ensure that the parametric domain is rectangular, and the parametric curve grid is regular. In order to overcome these limitations, we present a novel method for parameterization of triangular meshes in this paper. The basic idea is twofold: first, because the isotherms in the steady temperature do not intersect with each other, and are distributed uniformly, no singularity (fold-over) exists in the parameterization; second, a 3D harmonic equation is solved by the finite element method to obtain the steady temperature field on a 2D triangular mesh surface with four boundaries. Therefore, our proposed method avoids the embarrassment that it is impossible to solve the 2D quasi-harmonic equation on the 2D triangular mesh without the parametric values at mesh vertices. Furthermore, the isotherms on the temperature field are taken as a set of iso-parametric curves on the triangular mesh surface. The other set of iso-parametric curves can be obtained by connecting the points with the same chord-length on the isotherms sequentially. The obtained parametric curve grid is regular, and distributed uniformly, and can map the triangular mesh surface to the unit square domain with boundaries of mesh surface to boundaries of parametric domain, which ensures that the triangular mesh surface or point cloud can be fitted with the NURBS surface.

  5. Guaranteed-Quality Triangular Meshes

    Science.gov (United States)

    1989-04-01

    Defense Ad, : ed Research P: jects Pgency or the U.S- Gower ment° iI Guaranteed-Quality Triangular Meshes DTIC ELECTE L. Paul Chew* JUL 1419891 TR 89-983 S... Wittchen , M. S. Shephard, K. R. Grice, and M. A. Yerry, Robust, geometrically based, automatic two-dimensional mesh generation, International Journal for

  6. An Improved Moving Mesh Algorithm

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    we consider an iterative algorithm of mesh optimization for finite element solution, and give an improved moving mesh strategy that reduces rapidly the complexity and cost of solving variational problems.A numerical result is presented for a 2-dimensional problem by the improved algorithm.

  7. Adaptive and Unstructured Mesh Cleaving

    Science.gov (United States)

    Bronson, Jonathan R.; Sastry, Shankar P.; Levine, Joshua A.; Whitaker, Ross T.

    2015-01-01

    We propose a new strategy for boundary conforming meshing that decouples the problem of building tetrahedra of proper size and shape from the problem of conforming to complex, non-manifold boundaries. This approach is motivated by the observation that while several methods exist for adaptive tetrahedral meshing, they typically have difficulty at geometric boundaries. The proposed strategy avoids this conflict by extracting the boundary conforming constraint into a secondary step. We first build a background mesh having a desired set of tetrahedral properties, and then use a generalized stenciling method to divide, or “cleave”, these elements to get a set of conforming tetrahedra, while limiting the impacts cleaving has on element quality. In developing this new framework, we make several technical contributions including a new method for building graded tetrahedral meshes as well as a generalization of the isosurface stuffing and lattice cleaving algorithms to unstructured background meshes. PMID:26137171

  8. Quality of life research: types of publication output over time for cancer patients, a systematic review.

    Science.gov (United States)

    Bailey, L J; Sanson-Fisher, R; Aranda, S; D'Este, C; Sharkey, K; Schofield, P

    2010-09-01

    To examine the type of published research regarding quality of life for cancer patients over two 24-month periods: 1995-1996 and 2005-2006. A computer-based literature search was conducted using Medline. Two random samples of 120 publications identified in 1995-1996 and in 2005-2006 were coded as data-based research, reviews or programme descriptions. Data-based publications were further coded as measurement, descriptive or intervention research. Intervention publications were coded as psychosocial- or biomedical-based. Psychosocial intervention papers were coded using Cochrane Review criteria. In 1995-1996, 419 publications were identified and 1271 publications in 2005-2006. The majority of publications were data-based. The proportion of types of publications (data-based, reviews or programme description/case report categories) did not change significantly over time. Descriptive research dominated data-based publication outputs in 1995-1996 and 2005-2006. The current approach to quality of life research for cancer patients may be less than optimal for providing successful development of knowledge, improving healthcare delivery and lessening the burden of suffering.

  9. Mesh fixation methods in open inguinal hernia repair: a protocol for network meta-analysis and trial sequential analysis of randomised controlled trials

    Science.gov (United States)

    Ge, Long; Tian, Jin-hui; Li, Lun; Wang, Quan; Yang, Ke-hu

    2015-01-01

    Introduction Randomised clinical trials (RCTs) have been used to compare and evaluate different types of mesh fixation usually employed to repair open inguinal hernia. However, there is no consensus among surgeons on the best type of mesh fixation method to obtain optimal results. The choice often depends on surgeons’ personal preference. This study aims to compare different types of mesh fixation methods to repair open inguinal hernias and their role in the incidences of chronic groin pain, risk of hernia recurrence, complications, operative time, length of hospital stay and postoperative pain, using Bayesian network meta-analysis and trial sequential analysis of RCTs. Methods and analysis A systematic search will be performed using PubMed, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Chinese Biomedical Literature Database (CBM) and Chinese Journal Full-text Database, to include RCTs of different mesh fixation methods (or fixation vs no fixation) during open inguinal hernia repair. The risk of bias in included RCTs will be evaluated according to the Cochrane Handbook V.5.1.0. Standard pairwise meta-analysis, trial sequential analysis and Bayesian network meta-analysis will be performed to compare the efficacy of different mesh fixation methods. Ethics and dissemination Ethical approval and patient consent are not required since this study is a meta-analysis based on published studies. The results of this network meta-analysis and trial sequential analysis will be submitted to a peer-reviewed journal for publication. Protocol registration number PROSPERO CRD42015023758. PMID:26586326

  10. Streaming Compression of Hexahedral Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Isenburg, M; Courbet, C

    2010-02-03

    We describe a method for streaming compression of hexahedral meshes. Given an interleaved stream of vertices and hexahedral our coder incrementally compresses the mesh in the presented order. Our coder is extremely memory efficient when the input stream documents when vertices are referenced for the last time (i.e. when it contains topological finalization tags). Our coder then continuously releases and reuses data structures that no longer contribute to compressing the remainder of the stream. This means in practice that our coder has only a small fraction of the whole mesh in memory at any time. We can therefore compress very large meshes - even meshes that do not file in memory. Compared to traditional, non-streaming approaches that load the entire mesh and globally reorder it during compression, our algorithm trades a less compact compressed representation for significant gains in speed, memory, and I/O efficiency. For example, on the 456k hexahedra 'blade' mesh, our coder is twice as fast and uses 88 times less memory (only 3.1 MB) with the compressed file increasing about 3% in size. We also present the first scheme for predictive compression of properties associated with hexahedral cells.

  11. Mesh Adaptation and Shape Optimization on Unstructured Meshes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR CRM proposes to implement the entropy adjoint method for solution adaptive mesh refinement into the Loci/CHEM unstructured flow solver. The scheme will...

  12. A Survey of Solver-Related Geometry and Meshing Issues

    Science.gov (United States)

    Masters, James; Daniel, Derick; Gudenkauf, Jared; Hine, David; Sideroff, Chris

    2016-01-01

    There is a concern in the computational fluid dynamics community that mesh generation is a significant bottleneck in the CFD workflow. This is one of several papers that will help set the stage for a moderated panel discussion addressing this issue. Although certain general "rules of thumb" and a priori mesh metrics can be used to ensure that some base level of mesh quality is achieved, inadequate consideration is often given to the type of solver or particular flow regime on which the mesh will be utilized. This paper explores how an analyst may want to think differently about a mesh based on considerations such as if a flow is compressible vs. incompressible or hypersonic vs. subsonic or if the solver is node-centered vs. cell-centered. This paper is a high-level investigation intended to provide general insight into how considering the nature of the solver or flow when performing mesh generation has the potential to increase the accuracy and/or robustness of the solution and drive the mesh generation process to a state where it is no longer a hindrance to the analysis process.

  13. Nanowire mesh solar fuels generator

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Mersiline mesh in premaxillary augmentation.

    Science.gov (United States)

    Foda, Hossam M T

    2005-01-01

    Premaxillary retrusion may distort the aesthetic appearance of the columella, lip, and nasal tip. This defect is characteristically seen in, but not limited to, patients with cleft lip nasal deformity. This study investigated 60 patients presenting with premaxillary deficiencies in which Mersiline mesh was used to augment the premaxilla. All the cases had surgery using the external rhinoplasty technique. Two methods of augmentation with Mersiline mesh were used: the Mersiline roll technique, for the cases with central symmetric deficiencies, and the Mersiline packing technique, for the cases with asymmetric deficiencies. Premaxillary augmentation with Mersiline mesh proved to be simple technically, easy to perform, and not associated with any complications. Periodic follow-up evaluation for a mean period of 32 months (range, 12-98 months) showed that an adequate degree of premaxillary augmentation was maintained with no clinically detectable resorption of the mesh implant.

  15. GENERATION OF IRREGULAR HEXAGONAL MESHES

    Directory of Open Access Journals (Sweden)

    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.

  16. A study on moving mesh finite element solution of the porous medium equation

    Science.gov (United States)

    Ngo, Cuong; Huang, Weizhang

    2017-02-01

    An adaptive moving mesh finite element method is studied for the numerical solution of the porous medium equation with and without variable exponents and absorption. The method is based on the moving mesh partial differential equation approach and employs its newly developed implementation. The implementation has several improvements over the traditional one, including its explicit, compact form of the mesh velocities, ease to program, and less likelihood of producing singular meshes. Three types of metric tensor that correspond to uniform and arclength-based and Hessian-based adaptive meshes are considered. The method shows first-order convergence for uniform and arclength-based adaptive meshes, and second-order convergence for Hessian-based adaptive meshes. It is also shown that the method can be used for situations with complex free boundaries, emerging and splitting of free boundaries, and the porous medium equation with variable exponents and absorption. Two-dimensional numerical results are presented.

  17. Image-driven mesh optimization

    Energy Technology Data Exchange (ETDEWEB)

    Lindstrom, P; Turk, G

    2001-01-05

    We describe a method of improving the appearance of a low vertex count mesh in a manner that is guided by rendered images of the original, detailed mesh. This approach is motivated by the fact that greedy simplification methods often yield meshes that are poorer than what can be represented with a given number of vertices. Our approach relies on edge swaps and vertex teleports to alter the mesh connectivity, and uses the downhill simplex method to simultaneously improve vertex positions and surface attributes. Note that this is not a simplification method--the vertex count remains the same throughout the optimization. At all stages of the optimization the changes are guided by a metric that measures the differences between rendered versions of the original model and the low vertex count mesh. This method creates meshes that are geometrically faithful to the original model. Moreover, the method takes into account more subtle aspects of a model such as surface shading or whether cracks are visible between two interpenetrating parts of the model.

  18. Method and system for mesh network embedded devices

    Science.gov (United States)

    Wang, Ray (Inventor)

    2009-01-01

    A method and system for managing mesh network devices. A mesh network device with integrated features creates an N-way mesh network with a full mesh network topology or a partial mesh network topology.

  19. A Map-Based Service Supporting Different Types of Geographic Knowledge for the Public.

    Science.gov (United States)

    Zhou, Mengjie; Wang, Rui; Tian, Jing; Ye, Ning; Mai, Shumin

    2016-01-01

    The internet enables the rapid and easy creation, storage, and transfer of knowledge; however, services that transfer geographic knowledge and facilitate the public understanding of geographic knowledge are still underdeveloped to date. Existing online maps (or atlases) can support limited types of geographic knowledge. In this study, we propose a framework for map-based services to represent and transfer different types of geographic knowledge to the public. A map-based service provides tools to ensure the effective transfer of geographic knowledge. We discuss the types of geographic knowledge that should be represented and transferred to the public, and we propose guidelines and a method to represent various types of knowledge through a map-based service. To facilitate the effective transfer of geographic knowledge, tools such as auxiliary background knowledge and auxiliary map-reading tools are provided through interactions with maps. An experiment conducted to illustrate our idea and to evaluate the usefulness of the map-based service is described; the results demonstrate that the map-based service is useful for transferring different types of geographic knowledge.

  20. [Evaluation of public drug provision policies for type 2 diabetes mellitus in Argentina: a case study].

    Science.gov (United States)

    Elorza, María Eugenia; Moscoso, Nebel Silvana; Ripari, Nadia Vanina

    2012-01-01

    In Argentina, the provision of drugs for patients suffering from type 2 diabetes mellitus who lack health insurance is carried out through public programs. In the Province of Buenos Aires, the national program Remediar and the provincial program PRODIABA (from the Spanish Programa de Prevención, Diagnóstico y Tratamiento del Paciente Diabético) coexist. This study estimates the percentage of adults in the municipality of Bahia Blanca (Province of Buenos Aires) who suffer from type 2 diabetes mellitus and lack health insurance, thus satisfying their need for oral antidiabetic treatments within the public sector. It is a quantitative study that assesses the need and demand for public provision. The results indicate that: 1) the greatest percentage of demand is satisfied at the primary health care level; 2) the province of Buenos Aires funds the largest share of the pills, followed by the municipal and the national levels; 3) the local government intervenes to satisfy the demand and 4) the total public provision covers approximately 25% of the overall need in relation to the average consumption. This shows that despite the presence of these public programs, the provision is insufficient and thus requires the intervention of the local government even though economic theory does not recommend the decentralization of drug purchases.

  1. Mesh refinement strategy for optimal control problems

    OpenAIRE

    Paiva, Luis Tiago; Fontes, Fernando,

    2013-01-01

    International audience; Direct methods are becoming the most used technique to solve nonlinear optimal control problems. Regular time meshes having equidistant spacing are frequently used. However, in some cases these meshes cannot cope accurately with nonlinear behavior. One way to improve the solution is to select a new mesh with a greater number of nodes. Another way, involves adaptive mesh refinement. In this case, the mesh nodes have non equidistant spacing which allow a non uniform node...

  2. Mesh Router Nodes placement in Rural Wireless Mesh Networks

    OpenAIRE

    Ebongue, Jean Louis Fendji Kedieng; Thron, Christopher; Nlong, Jean Michel

    2015-01-01

    The problem of placement of mesh router nodes in Wireless Mesh Networks is known to be a NP hard problem. In this paper, the problem is addressed under a constraint of network model tied to rural regions where we usually observe low density and sparse population. We consider the area to cover as decomposed into a set of elementary areas which can be required or optional in terms of coverage and where a node can be placed or not. We propose an effective algorithm to ensure the coverage. This a...

  3. A Metropolis Approach for Mesh Router Nodes placement in Rural Wireless Mesh Networks

    OpenAIRE

    Fendji, Jean Louis Ebongue Kedieng; Thron, Christopher; Nlong, Jean Michel

    2015-01-01

    Wireless mesh networks appear as an appealing solution to reduce the digital divide between rural and urban regions. However the placement of router nodes is still a critical issue when planning this type of network, especially in rural regions where we usually observe low density and sparse population. In this paper, we firstly provide a network model tied to rural regions by considering the area to cover as decomposed into a set of elementary areas which can be required or optional in terms...

  4. How professionals perceive types of risk in public service innovation: Reports from Copenhagen municipality

    DEFF Research Database (Denmark)

    Timeus, Krista; Ricard, Lykke Margot

    The paper addresses two questions; what do professionals working in the public administration understand by ‘risk’ in relation to their work on innovation?; and how do these professionals understand their own role in managing risks of innovation? The paper takes an inductive approach and focuses...... on individuals, namely, professionals in Copenhagen municipality working on public services innovation. Such innovation includes new services or new methods of service delivery. Although all types of innovation include some risk, in public services, risks are exacerbated by the vulnerability of many users...... dependent on the state (such as children, elderly, people with disabilities), and intense media and political attention.Thus, most of the discussion in the paper focuses on innovations that somehow involve users. This is in contrast to, for example, an organizational innovation that mainly affects workers...

  5. Phraseological units in the language of public service advertising: occasional configuration of the first type

    Directory of Open Access Journals (Sweden)

    Soboleva Nina Pavlovna

    2015-06-01

    Full Text Available The paper covers the implementation of phraseological units in the language of public service advertising, as well as theoretical and practical aspects of phraseological units and their contextual use. The research is aimed at the analysis, classification of the cases of implementation and identification of the main structural and semantic classes of phraseological units used in public service advertising slogans in the Russian, English and German languages. The choice of practical material is stipulated by a growing role of public service advertising and interest in this issue. As a result of our research we analysed three thousand slogans in three languages taken from posters and websites. The author dwells on occasional configuration of the first type, introduced by A.V. Kunin, and considers the following stylistic modifications: dual actualisation, substitution, ellipsis, extension, permutation and other. A relevant classification is introduced which covers the stylistic modifications implemented in public service advertising slogans in three languages. The most frequently used stylistic modifications are identified. The most commonly used structure types of phraseological units are revealed in the article. No matter what kind of modification is explored the reasons of transformation can be the following: the structure of PU, the inner form and pragmatics.

  6. Molecular Typing in Public Health Laboratories: From an Academic Indulgence to an Infection Control Imperative

    OpenAIRE

    2012-01-01

    Using three Austrian case studies, the variegated applications of molecular typing in today's public health laboratories are discussed to help illustrate preventive management strategies relying on DNA subtyping. DNA macrorestriction analysis by pulsed field gel electrophoresis has become the gold standard for subtyping of food borne pathogens like listeria, salmonella, campylobacter and Bacillus cereus. Using a Salmonella Mbandaka outbreak from the year 2010 as example, it is shown how the c...

  7. Efficient Packet Forwarding in Mesh Network

    CERN Document Server

    Kanrar, Soumen

    2012-01-01

    Wireless Mesh Network (WMN) is a multi hop low cost, with easy maintenance robust network providing reliable service coverage. WMNs consist of mesh routers and mesh clients. In this architecture, while static mesh routers form the wireless backbone, mesh clients access the network through mesh routers as well as directly meshing with each other. Different from traditional wireless networks, WMN is dynamically self-organized and self-configured. In other words, the nodes in the mesh network automatically establish and maintain network connectivity. Over the years researchers have worked, to reduce the redundancy in broadcasting packet in the mesh network in the wireless domain for providing reliable service coverage, the source node deserves to broadcast or flood the control packets. The redundant control packet consumes the bandwidth of the wireless medium and significantly reduces the average throughput and consequently reduces the overall system performance. In this paper I study the optimization problem in...

  8. On Linear Spaces of Polyhedral Meshes.

    Science.gov (United States)

    Poranne, Roi; Chen, Renjie; Gotsman, Craig

    2015-05-01

    Polyhedral meshes (PM)-meshes having planar faces-have enjoyed a rise in popularity in recent years due to their importance in architectural and industrial design. However, they are also notoriously difficult to generate and manipulate. Previous methods start with a smooth surface and then apply elaborate meshing schemes to create polyhedral meshes approximating the surface. In this paper, we describe a reverse approach: given the topology of a mesh, we explore the space of possible planar meshes having that topology. Our approach is based on a complete characterization of the maximal linear spaces of polyhedral meshes contained in the curved manifold of polyhedral meshes with a given topology. We show that these linear spaces can be described as nullspaces of differential operators, much like harmonic functions are nullspaces of the Laplacian operator. An analysis of this operator provides tools for global and local design of a polyhedral mesh, which fully expose the geometric possibilities and limitations of the given topology.

  9. Prevalence and types of misrepresentation of publication record by pathology residency applicants.

    Science.gov (United States)

    Kaley, Jennifer Raible; Bornhorst, Joshua; Wiggins, Michael; Yared, Marwan

    2013-07-01

    Publication misrepresentation among residency applicants has been demonstrated in various specialties. This study examines the prevalence of publication misrepresentation among US-trained and non-US-trained pathology residency applicants. To determine the prevalence of publication misrepresentation in the pathology applicant pool at our institution, to compare the rates of misrepresentation among US-trained and non-US-trained applicants, and to compare results to published results from other medical specialties. All peer-reviewed journal articles reported on applications to our program in 2010 and 2011 were examined for veracity. Applications from current or past trainees and applications with unverifiable manuscripts were excluded. The type of misrepresentation and the country in which the applicant trained were recorded. Seven hundred applications were reviewed. Of 319 (46%) reported publications, 25 were from US graduates (8%) and 294 (92%) were from non-US graduates. Eighty-six applications were excluded owing to unverifiable manuscripts. Publication misrepresentations were found in 42 (18%) of the remaining 233 applications. The most common misrepresentations were omission of authors (69%), nonauthorship (14%), and self-promotion on the author list (12%). A significantly higher percentage of foreign medical graduates listed publications (P misrepresentation rate by foreign graduates (19%) did not differ significantly from that of US-trained graduates (13%) (P = .45). Publication misrepresentation was present among pathology residency applicants. Similar rates were seen among US and non-US applicants. Percentages of misrepresentation among applicants to our pathology program and applicants to other medical specialties (18% and 17%, respectively) were comparable.

  10. Evaluation of adhesion formation and host tissue response to intra-abdominal polytetrafluoroethylene mesh and composite prosthetic mesh.

    Science.gov (United States)

    Matthews, Brent D; Mostafa, Gamal; Carbonell, Alfredo M; Joels, Charles S; Kercher, Kent W; Austin, Catherine; Norton, H James; Heniford, B Todd

    2005-02-01

    The purpose of this study was to measure the extent of adhesion formation to ePTFE mesh (DualMesh, W.L. Gore & Associates, Inc, Flagstaff, AZ) and two composite prosthetic materials, ePTFE and polypropylene (Bard Composix, C.R. Bard, Inc, Murray Hill, NJ) and hyaluronic acid/carboxymethylcellulose and polypropylene (Sepramesh, Genzyme Corp, Cambridge, MA) after their intra-abdominal placement on an intact peritoneum, simulating laparoscopic ventral hernia repair, and to evaluate host tissue response to the prosthetic biomaterials. Through a midline laparotomy, a 2 x 2 cm piece of mesh (n = 60) was sewn to an intact peritoneum on each side of a midline incision in 30 New Zealand white rabbits. Mesh adhesions were scored using a modified Diamond scale (0 = 0%, 1 = 1-25%, 2 = 26-50%, 3 >50%) at 1, 3, 9, and 16 weeks by serial microlaparoscopy (2 mm). All laparoscopic evaluations were videotaped for blinded scoring by three surgeons. Host tissue response was graded (1-4) for inflammation, tissue ingrowth, and mesothelialization. The predominant cell type (polymorphonuclear leukocytes versus foreign body giant cell) was recorded. Statistical differences (P value DualMesh) intra-abdominal against an intact peritoneum results in significantly fewer adhesions than the composite prosthetic meshes during a 4-month follow-up. The host tissue response is equivalent for the three prosthetic biomaterials. The long-term consequences of increased adhesion formation to the composite meshes and the ultimate biocompatibility of the nonabsorbable and absorbable barriers on the polypropylene mesh are to be determined.

  11. [Meta-Mesh: metagenomic data analysis system].

    Science.gov (United States)

    Su, Xiaoquan; Song, Baoxing; Wang, Xuetao; Ma, Xinle; Xu, Jian; Ning, Kang

    2014-01-01

    With the current accumulation of metagenome data, it is possible to build an integrated platform for processing of rigorously selected metagenomic samples (also referred as "metagenomic communities" here) of interests. Any metagenomic samples could then be searched against this database to find the most similar sample(s). However, on one hand, current databases with a large number of metagenomic samples mostly serve as data repositories but not well annotated database, and only offer few functions for analysis. On the other hand, the few available methods to measure the similarity of metagenomic data could only compare a few pre-defined set of metagenome. It has long been intriguing scientists to effectively calculate similarities between microbial communities in a large repository, to examine how similar these samples are and to find the correlation of the meta-information of these samples. In this work we propose a novel system, Meta-Mesh, which includes a metagenomic database and its companion analysis platform that could systematically and efficiently analyze, compare and search similar metagenomic samples. In the database part, we have collected more than 7 000 high quality and well annotated metagenomic samples from the public domain and in-house facilities. The analysis platform supplies a list of online tools which could accept metagenomic samples, build taxonomical annotations, compare sample in multiple angle, and then search for similar samples against its database by a fast indexing strategy and scoring function. We also used case studies of "database search for identification" and "samples clustering based on similarity matrix" using human-associated habitat samples to demonstrate the performance of Meta-Mesh in metagenomic analysis. Therefore, Meta-Mesh would serve as a database and data analysis system to quickly parse and identify similar

  12. Current developments in hernia repair; meshes, adhesives, and tacking.

    Science.gov (United States)

    Powell, Benjamin S; Voeller, Guy R

    2010-10-01

    Open and laparoscopic hernia surgery continues to evolve with new products allowing surgeons multiple choices in treating their patients. The evolution towards tension-free techniques in dealing with hernias requires that today's surgeons know the options available in meshes as well as fixation methods in order to have the best outcomes. In recent years, there has been a rapid expansion in the number of meshes available. Currently, there are numerous uncoated, coated, and biologic meshes in production that can be used in hernia repair. This paper will focus on the latest developments in coated meshes that allow for intra-abdominal placement as well as the different types of biologic meshes and their typical uses. Tacking devices for laparoscopic hernia repair now come in titanium as well as absorbable devices. AbsorbaTack™ (Covidien, Norwalk, CT) and Sorbafix™ (Davol, Warwick, RI) are two of the newest absorbable tacking devices thought to possibly benefit patients with decreased pain and long-term complications as compared with their titanium counterparts. Adhesives continue to be used more and more for hernia repair, especially in inguinal and paraesophageal hernia repairs. Tissucol™/Tisseel™ (Baxter, Deerfield, IL) and Evicel™ (Ethicon, Somerville, NJ) are two types of fibrin glues that are available for use in hernia repair. Practitioners using these biologic adhesives think there is less pain compared with tacking.

  13. Advances in the development of wire mesh reactor for coal gasification studies.

    Science.gov (United States)

    Zeng, Cai; Chen, Lei; Liu, Gang; Li, Wenhua; Huang, Baoming; Zhu, Hongdong; Zhang, Bing; Zamansky, Vladimir

    2008-08-01

    In an effort to further understand the coal gasification behavior in entrained-flow gasifiers, a high pressure and high temperature wire mesh reactor with new features was recently built. An advanced LABVIEW-based temperature measurement and control system were adapted. Molybdenum wire mesh with aperture smaller than 70 mum and type D thermocouple were used to enable high carbon conversion (>90%) at temperatures >1000 degrees C. Gaseous species from wire mesh reactor were quantified using a high sensitivity gas chromatography. The material balance of coal pyrolysis in wire mesh reactor was demonstrated for the first time by improving the volatile's quantification techniques.

  14. A set of mixed-elements patterns for domain boundary approximation in hexahedral meshes.

    Science.gov (United States)

    Lobos, Claudio

    2013-01-01

    Hexahedral meshes are largely used by the Finite Element Method in a high variety of simulation problems. One of the most common problems of these type of meshes is to achieve an adequate approximation of curved domains; a feature typically found in the shape of organs. This work introduces a set of mixed-elements patterns, which are employed at the surface of target domain, and allow to conserve hexahedra elsewhere. These patterns are meant to be combined with any meshing technique producing a regular or non-regular hexahedral mesh.

  15. Inching toward 'push-button' meshing

    National Research Council Canada - National Science Library

    James Masters

    2015-01-01

      While "push-button" meshing remains an elusive goal, advances in 2015 have brought the technology to the point where meshes can be constructed with relative ease when appropriate surfaces are available...

  16. Public Speech.

    Science.gov (United States)

    Green, Thomas F.

    1994-01-01

    Discusses the importance of public speech in society, noting the power of public speech to create a world and a public. The paper offers a theory of public speech, identifies types of public speech, and types of public speech fallacies. Two ways of speaking of the public and of public life are distinguished. (SM)

  17. 象山港两种网目网采浮游动物群落比较%A comparison of zooplankton communities collected by two types of nets with different mesh sizes in Xiangshan Bay of Zhejiang, East China

    Institute of Scientific and Technical Information of China (English)

    朱艺峰; 王银; 林霞; 吴燕萍; 赵金龙; 严小军

    2012-01-01

    分别于2010年3月(春)、7月(夏)、9月(秋)、12月(冬),用浮游生物Ⅰ型(网目505 μm)、Ⅱ型(网目160 μm)网同步在象山港进行6站位2重复的浮游动物取样,比较分析了不同时空下两种网目采集的浮游动物群落差异.结果表明:两网间的浮游动物种类数、丰度、生物量、优势种和群落格局都存在极大差异.其中,Ⅰ网的种类数(61种,包括幼虫)、平均丰度(139.0 ind·m-3)和平均生物量(86.1 mg·m-3)显著低于Ⅱ网(分别为84种、3780.2 ind· m-3和191.1 mg · m-3).在优势种中,除太平洋纺锤水蚤和墨氏胸刺水蚤为两网共有优势种外,其余优势种完全不同.Ⅰ网末检出周年的优势种,而Ⅱ网的周年优势种是针刺拟哲水蚤和桡足类幼体.相似性分析(ANOSIM)和nMDS排序结果显示,两网群落格局不仅在时空上存在显著差异,而且I网群落比Ⅱ网更离散.相似性百分比(SIMPER)分析进一步揭示,两网群落格局间平均非相似性高达75%以上,造成两网群落时空非相似性差异的主要判别种是:针刺拟哲水蚤、桡足类幼体、强额拟哲水蚤和短角长腹剑水蚤,而这些种均为Ⅱ网的优势种.表明象山港浮游动物调查时以Ⅱ网更具代表性.%In March ( spring) , July ( summer) , September ( autumn) , and December ( winter) 2010, the zooplanktons at six stations in Xiangshan Bay were sampled simultaneously by the nets with a mesh size of 505 μm (net type Ⅰ ) and of 160 p,m (net type Ⅱ ) , and each sampling had two replicates. The spatiotemporal differences in the zooplanktons communities collected by the two types of nets were compared. There existed great differences in the species number, abundance, biomass, dominant species, and community pattern between the zooplanktons collected by the two types of nets. The species number, average abundance, and average biomass of the zooplanktons collected by net type Ⅰ (61 species including larvae, 139. 0 ind · m

  18. Comparing Teaching Styles and Personality Types of EFL Instructors in the Public and Private Sectors

    Directory of Open Access Journals (Sweden)

    Diaz Larenas Claudio H.

    2011-04-01

    Full Text Available

    This is an exploratory non-experimental research study whose main objective is to compare the teaching styles of a group of thirty teachers of English working in either public or private secondary education in Chile. In order to collect the required data, two instruments were administered to the participants: a teaching style inventory and a personality type index proposed by Grasha. Results indicate that public sector participants show a facilitator teaching style and an extrovert personality type, whereas private sector participants reveal a more authoritative teaching style and an introverted type of personality.

    Este estudio exploratorio de naturaleza no-experimental tiene como objetivo principal comparar los estilos de enseñanza de un grupo de treinta profesores de inglés que trabajan en el nivel de enseñanza secundario del sistema educativo estatal o privado, en Chile. Para la recolección de datos se utilizaron el inventario de estilos de enseñanza y el índice de tipo de personalidad de Grasha. Los resultados indican que los participantes del nivel de enseñanza estatal presentan un estilo de enseñanza de naturaleza facilitadora y un tipo de personalidad extrovertido, mientras que los participantes del nivel de enseñanza privado revelan un estilo de enseñanza más autoritario y una personalidad más introvertida.

  19. Particle Collection Efficiency for Nylon Mesh Screens

    OpenAIRE

    Cena, Lorenzo G.; Ku, Bon-Ki; Peters, Thomas M.

    2011-01-01

    Mesh screens composed of nylon fibers leave minimal residual ash and produce no significant spectral interference when ashed for spectrometric examination. These characteristics make nylon mesh screens attractive as a collection substrate for nanoparticles. A theoretical single-fiber efficiency expression developed for wire-mesh screens was evaluated for estimating the collection efficiency of submicrometer particles for nylon mesh screens. Pressure drop across the screens, the effect of part...

  20. 6th International Meshing Roundtable '97

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. 50 CFR 300.110 - Mesh size.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Mesh size. 300.110 Section 300.110... Antarctic Marine Living Resources § 300.110 Mesh size. (a) The use of pelagic and bottom trawls having the mesh size in any part of a trawl less than indicated is prohibited for any directed fishing for the...

  2. Markov Random Fields on Triangle Meshes

    DEFF Research Database (Denmark)

    Andersen, Vedrana; Aanæs, Henrik; Bærentzen, Jakob Andreas

    2010-01-01

    mesh edges according to a feature detecting prior. Since we should not smooth across a sharp feature, we use edge labels to control the vertex process. In a Bayesian framework, MRF priors are combined with the likelihood function related to the mesh formation method. The output of our algorithm...... is a piecewise smooth mesh with explicit labelling of edges belonging to the sharp features....

  3. Mesh network achieve its fuction on Linux

    OpenAIRE

    Pei Ping; PETRENKO Y.N.

    2015-01-01

    In this paper, we introduce a Mesh network protocol evaluation and development. It has a special protocol. We could easily understand the Linux operation principles which are in use in mesh network. In addition to our comprehension, we describe the graph which shows package routing way. At last according to testing we prove that Mesh protocol AODV satisfy Linux platform performance requirements.

  4. The mesh network protocol evaluation and development

    OpenAIRE

    Pei Ping; PETRENKO Y.N.

    2015-01-01

    In this paper, we introduce a Mesh network protocol evaluation and development. It has a special protocol. We could easily to understand that how different protocols are used in mesh network. In addition to our comprehension, Multi – hop routing protocol could provide robustness and load balancing to communication in wireless mesh networks.

  5. A curated public database for multilocus sequence typing (MLST) and analysis of Haemophilus parasuis based on an optimized typing scheme.

    Science.gov (United States)

    Mullins, Michael A; Register, Karen B; Brunelle, Brian W; Aragon, Virginia; Galofré-Mila, Nuria; Bayles, Darrell O; Jolley, Keith A

    2013-03-23

    Haemophilus parasuis causes Glässer's disease and pneumonia in swine. Serotyping is often used to classify isolates but requires reagents that are costly to produce and not standardized or widely available. Sequence-based methods, such as multilocus sequence typing (MLST), offer many advantages over serotyping. An MLST scheme was previously proposed for H. parasuis but genome sequence data only recently available reveals the primers recommended, based on sequences of related bacteria, are not optimal. Here we report modifications to enhance the original method, including primer redesign to eliminate mismatches with H. parasuis sequences and to avoid regions of high sequence heterogeneity, standardization of primer T(m)s and identification of universal PCR conditions that result in robust and reproducible amplification of all targets. The modified typing method was applied to a collection of 127 isolates from North and South America, Europe and Asia. An alignment of the concatenated sequences obtained from seven target housekeeping genes identified 278 variable nucleotide sites that define 116 unique sequence types. A comparison of the original and modified methods using a subset of 86 isolates indicates little difference in overall locus diversity, discriminatory power or in the clustering of strains within Neighbor-Joining trees. Data from the optimized MLST were used to populate a newly created and publicly available H. parasuis database. An accompanying database designed to capture provenance and epidemiological information for each isolate was also created. The modified MLST scheme is highly discriminatory but more robust, reproducible and user-friendly than the original. The MLST database provides a novel resource for investigation of H. parasuis outbreaks and for tracking strain evolution.

  6. A coarse-mesh nodal method-diffusive-mesh finite difference method

    Energy Technology Data Exchange (ETDEWEB)

    Joo, H.; Nichols, W.R.

    1994-05-01

    Modern nodal methods have been successfully used for conventional light water reactor core analyses where the homogenized, node average cross sections (XSs) and the flux discontinuity factors (DFs) based on equivalence theory can reliably predict core behavior. For other types of cores and other geometries characterized by tightly-coupled, heterogeneous core configurations, the intranodal flux shapes obtained from a homogenized nodal problem may not accurately portray steep flux gradients near fuel assembly interfaces or various reactivity control elements. This may require extreme values of DFs (either very large, very small, or even negative) to achieve a desired solution accuracy. Extreme values of DFs, however, can disrupt the convergence of the iterative methods used to solve for the node average fluxes, and can lead to a difficulty in interpolating adjacent DF values. Several attempts to remedy the problem have been made, but nothing has been satisfactory. A new coarse-mesh nodal scheme called the Diffusive-Mesh Finite Difference (DMFD) technique, as contrasted with the coarse-mesh finite difference (CMFD) technique, has been developed to resolve this problem. This new technique and the development of a few-group, multidimensional kinetics computer program are described in this paper.

  7. Mesh Resolution Effect on 3D RANS Turbomachinery Flow Simulations

    CERN Document Server

    Yershov, Sergiy

    2016-01-01

    The paper presents the study of the effect of a mesh refinement on numerical results of 3D RANS computations of turbomachinery flows. The CFD solver F, which based on the second-order accurate ENO scheme, is used in this study. The simplified multigrid algorithm and local time stepping permit decreasing computational time. The flow computations are performed for a number of turbine and compressor cascades and stages. In all flow cases, the successively refined meshes of H-type with an approximate orthogonalization near the solid walls were generated. The results obtained are compared in order to estimate their both mesh convergence and ability to resolve the transonic flow pattern. It is concluded that for thorough studying the fine phenomena of the 3D turbomachinery flows, it makes sense to use the computational meshes with the number of cells from several millions up to several hundred millions per a single turbomachinery blade channel, while for industrial computations, a mesh of about or less than one mil...

  8. LICHENSTEIN TENSION FREE MESH HERNIOPLASTY: A PROSPECTIVE STUDY

    Directory of Open Access Journals (Sweden)

    Rakesh K

    2014-12-01

    Full Text Available : INTRODUCTION: Mesh inguinal hernioplasty is one of the most commonly performed surgery by general surgeons. One of the significant problems following hernia repair is recurrence. Prosthetic materials like polypropylene mesh has been used for inguinal hernia repair and has many advantages like low recurrence rates, less postoperative pain, decreased hospital stay and fewer complications. MATERIALS AND METHODS: In this prospective study, 432 open Lichenstein tension-free inguinal mesh hernioplasty was performed between June 2004 and May 2014. Various parameters regarding postoperative complications were studied. RESULTS: In 432 cases, inguinal hernia was indirect in 59.03% of cases (255 cases, direct in 36.57% (158 cases and of the pantaloon (mixed type in 4.39% (18 cases. Mean age of patients was 50.8 years (range 19–92. The median follow-up period was 2.1 years (range 1 month–5 years. Seroma and hematoma formation requiring drainage was observed in 9 and 11 patients, respectively, while transient testicular swelling occurred in 28 patients. We have not observed acute infection or abscess formation related to the presence of the foreign body (mesh. There was one recurrence of the hernia. Residual neuralgia was observed in 3 patients. CONCLUSION: Lichtenstein Tension-free mesh hernioplasty has many advantages of being simple, effective, low recurrence rate, early return to daily activities and good patient compliance and satisfaction. This technique is preferable for hernia repair in our setting.

  9. Correlation between shrinkage and infection of implanted synthetic meshes using an animal model of mesh infection.

    OpenAIRE

    Mamy, Laurent; Letouzey, Vincent; Lavigne, Jean-Philippe; Garric, Xavier; Gondry, Jean; Mares, Pierre; De Tayrac, Renaud

    2010-01-01

    International audience; INTRODUCTION AND HYPOTHESIS: The aim of this study was to evaluate a link between mesh infection and shrinkage. METHODS: Twenty-eight Wistar rats were implanted with synthetic meshes that were either non-absorbable (polypropylene (PP), n = 14) or absorbable (poly (D: ,L: -lactic acid) (PLA94), n = 14). A validated animal incisionnal abdominal hernia model of mesh infection was used. Fourteen meshes (n = 7 PLA94 and n = 7 PP meshes) were infected intraoperatively with 1...

  10. Adhesions to Mesh after Ventral Hernia Mesh Repair Are Detected by MRI but Are Not a Cause of Long Term Chronic Abdominal Pain

    Directory of Open Access Journals (Sweden)

    Odd Langbach

    2016-01-01

    Full Text Available Aim. The aim of the present study was to perform MRI in patients after ventral hernia mesh repair, in order to evaluate MRI’s ability to detect intra-abdominal adhesions. Materials and Methods. Single-center long term follow-up study of 155 patients operated for ventral hernia with laparoscopic (LVHR or open mesh repair (OVHR, including analyzing medical records, clinical investigation with patient-reported pain (VAS-scale, and MRI. MRI was performed in 124 patients: 114 patients (74% after follow-up, and 10 patients referred for late complaints after ventral mesh repair. To verify the MRI-diagnosis of adhesions, laparoscopy was performed after MRI in a cohort of 20 patients. Results. MRI detected adhesions between bowel and abdominal wall/mesh in 60% of the patients and mesh shrinkage in 20–50%. Adhesions were demonstrated to all types of meshes after both LVHR and OVHR with a sensitivity of 70%, specificity of 75%, positive predictive value of 78%, and negative predictive value of 67%. Independent predictors for formation of adhesions were mesh area as determined by MRI and Charlson index. The presence of adhesions was not associated with more pain. Conclusion. MRI can detect adhesions between bowel and abdominal wall in a fair reliable way. Adhesions are formed both after open and laparoscopic hernia mesh repair and are not associated with chronic pain.

  11. Comminuted Frontal Sinus Fracture Reconstructed With Titanium Mesh.

    Science.gov (United States)

    Sakat, Muhammed Sedat; Kilic, Korhan; Altas, Enver; Gozeler, Mustafa Sitki; Ucuncu, Harun

    2016-03-01

    Frontal sinus fractures (FSF) are relatively uncommon maxillofacial injuries. The most common cause of FSF is motor vehicle accidents with 62% percentage. Management of FSF depends on type of fracture, associated injuries, and involvement of naso-frontal duct. In this report, the authors presented a patient with comminuted fracture of anterior wall of frontal sinus reconstructed with titanium mesh. A 40-year-old man presented with depression of the frontal bone, facial pain, and epistaxis consisting of a motor vehicle accident. Computerized tomography scan revealed multiple comminuted fractures of anterior wall of frontal sinus and fractures of left orbital medial and superior walls. Titanium mesh was used for reconstruction. Postoperative course was uneventful. The titanium mesh, which is easy to handle with no complications, may provide excellent frontal contour after comminuted anterior wall fractures.

  12. 21st International Meshing Roundtable

    CERN Document Server

    Weill, Jean-Christophe

    2013-01-01

    This volume contains the articles presented at the 21st International Meshing Roundtable (IMR) organized, in part, by Sandia National Laboratories and was held on October 7–10, 2012 in San Jose, CA, USA. The first IMR was held in 1992, and the conference series has been held annually since. Each year the IMR brings together researchers, developers, and application experts in a variety of disciplines, from all over the world, to present and discuss ideas on mesh generation and related topics. The technical papers in this volume present theoretical and novel ideas and algorithms with practical potential, as well as technical applications in science and engineering, geometric modeling, computer graphics, and visualization.

  13. On the flexibility of Kokotsakis meshes

    OpenAIRE

    Karpenkov, Oleg

    2008-01-01

    In this paper we study geometric, algebraic, and computational aspects of flexibility and infinitesimal flexibility of Kokotsakis meshes. A Kokotsakis mesh is a mesh that consists of a face in the middle and a certain band of faces attached to the middle face by its perimeter. In particular any 3x3-mesh made of quadrangles is a Kokotsakis mesh. We express the infinitesimal flexibility condition in terms of Ceva and Menelaus theorems. Further we study semi-algebraic properties of the set of fl...

  14. [Pollutions of indoor fine particles in four types of public places and the influencing factors].

    Science.gov (United States)

    Liu, Bo; Deng, Fu-rong; Guo, Xin-biao; Yang, Dong-mei; Teng, Xiu-quan; Zheng, Xu; Gao, Jing; Dong, Jing; Wu, Shao-wei

    2009-08-01

    To study the levels of pollutions caused by fine particulate matter (PM(2.5)) in the public places and investigate the possible influencing factors. A total of 20 public places in four types such as rest room in bath center, restaurant, karaoke bars and cyber cafe in Tongzhou district in Beijing were chosen in this study; indoor and outdoor PM(2.5) was monitored by TSI sidepak AM510. Data under varying conditions were collected and analyzed, such as doors or windows or mechanical ventilation devices being opened, rooms cramped with people and smoking. The average concentration of indoor PM(2.5) in 20 public places was (334.6 +/- 386.3) microg/m(3), ranging from 6 microg/m(3) to 1956 microg/m(3); while in bath center, restaurant, karaoke bars and cyber cafe were (116.9 +/- 100.1)microg/m(3), (317.9 +/- 235.3) microg/m(3), (750.6 +/- 521.6)microg/m(3) and (157.5 +/- 98.5) microg/m(3) respectively. The concentrations of PM(2.5) in restaurant (compared with bath center: Z = -10.785, P 1.5) points; r = 0.667, F = 14.442, P 1.556, t = 3.760, P = 0.007] when ventilation (score > 2) was relatively good. The number of smokers per cube meters (14.7 x 10(-3)) became the major influence factor when the ventilation score public places. Outdoor PM(2.5) should be correlated with indoor PM(2.5) concentration under drafty situation.

  15. DISCO: A 3D Moving-Mesh Magnetohydrodynamics Code Designed for the Study of Astrophysical Disks

    CERN Document Server

    Duffell, Paul C

    2016-01-01

    This work presents the publicly available moving-mesh magnetohydrodynamics code DISCO. DISCO is efficient and accurate at evolving orbital fluid motion in two and three dimensions, especially at high Mach number. DISCO employs a moving-mesh approach utilizing a dynamic cylindrical mesh that can shear azimuthally to follow the orbital motion of the gas. The moving mesh removes diffusive advection errors and allows for longer timesteps than a static grid. Magnetohydrodynamics is implemented in DISCO using an HLLD Riemann solver and a novel constrained transport scheme which is compatible with the mesh motion. DISCO is tested against a wide variety of problems, which are designed to test its stability, accuracy and scalability. In addition, several magnetohydrodynamics tests are performed which demonstrate the accuracy and stability of the new constrained transport approach, including two tests of the magneto-rotational instability (MRI); one testing the linear growth rate and the other following the instability...

  16. DISCO: A 3D Moving-mesh Magnetohydrodynamics Code Designed for the Study of Astrophysical Disks

    Science.gov (United States)

    Duffell, Paul C.

    2016-09-01

    This work presents the publicly available moving-mesh magnetohydrodynamics (MHD) code DISCO. DISCO is efficient and accurate at evolving orbital fluid motion in two and three dimensions, especially at high Mach numbers. DISCO employs a moving-mesh approach utilizing a dynamic cylindrical mesh that can shear azimuthally to follow the orbital motion of the gas. The moving mesh removes diffusive advection errors and allows for longer time-steps than a static grid. MHD is implemented in DISCO using an HLLD Riemann solver and a novel constrained transport (CT) scheme that is compatible with the mesh motion. DISCO is tested against a wide variety of problems, which are designed to test its stability, accuracy, and scalability. In addition, several MHD tests are performed which demonstrate the accuracy and stability of the new CT approach, including two tests of the magneto-rotational instability, one testing the linear growth rate and the other following the instability into the fully turbulent regime.

  17. Image meshing via hierarchical optimization

    Institute of Scientific and Technical Information of China (English)

    Hao XIE; Ruo-feng TONG‡

    2016-01-01

    Vector graphic, as a kind of geometric representation of raster images, has many advantages, e.g., defi nition independence and editing facility. A popular way to convert raster images into vector graphics is image meshing, the aim of which is to fi nd a mesh to represent an image as faithfully as possible. For traditional meshing algorithms, the crux of the problem resides mainly in the high non-linearity and non-smoothness of the objective, which makes it difficult to fi nd a desirable optimal solution. To ameliorate this situation, we present a hierarchical optimization algorithm solving the problem from coarser levels to fi ner ones, providing initialization for each level with its coarser ascent. To further simplify the problem, the original non-convex problem is converted to a linear least squares one, and thus becomes convex, which makes the problem much easier to solve. A dictionary learning framework is used to combine geometry and topology elegantly. Then an alternating scheme is employed to solve both parts. Experiments show that our algorithm runs fast and achieves better results than existing ones for most images.

  18. Image meshing via hierarchical optimization*

    Institute of Scientific and Technical Information of China (English)

    Hao XIE; Ruo-feng TONGS

    2016-01-01

    Vector graphic, as a kind of geometric representation of raster images, has many advantages, e.g., definition independence and editing facility. A popular way to convert raster images into vector graphics is image meshing, the aim of which is to find a mesh to represent an image as faithfully as possible. For traditional meshing algorithms, the crux of the problem resides mainly in the high non-linearity and non-smoothness of the objective, which makes it difficult to find a desirable optimal solution. To ameliorate this situation, we present a hierarchical optimization algorithm solving the problem from coarser levels to finer ones, providing initialization for each level with its coarser ascent. To further simplify the problem, the original non-convex problem is converted to a linear least squares one, and thus becomes convex, which makes the problem much easier to solve. A dictionary learning framework is used to combine geometry and topology elegantly. Then an alternating scheme is employed to solve both parts. Experiments show that our algorithm runs fast and achieves better results than existing ones for most images.

  19. Grating droplets with a mesh

    Science.gov (United States)

    Soto, Dan; Le Helloco, Antoine; Clanet, Cristophe; Quere, David; Varanasi, Kripa

    2016-11-01

    A drop thrown against a mesh can pass through its holes if impacting with enough inertia. As a result, although part of the droplet may remain on one side of the sieve, the rest will end up grated through the other side. This inexpensive method to break up millimetric droplets into micrometric ones may be of particular interest in a wide variety of applications: enhancing evaporation of droplets launched from the top of an evaporative cooling tower or preventing drift of pesticides sprayed above crops by increasing their initial size and atomizing them at the very last moment with a mesh. In order to understand how much liquid will be grated we propose in this presentation to start first by studying a simpler situation: a drop impacting a plate pierced with a single off centered hole. The study of the role of natural parameters such as the radius drop and speed or the hole position, size and thickness allows us to discuss then the more general situation of a plate pierced with multiple holes: the mesh.

  20. Pamgen, a library for parallel generation of simple finite element meshes.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Long-term anisotropic mechanical response of surgical meshes used to repair abdominal wall defects.

    Science.gov (United States)

    Hernández-Gascón, B; Peña, E; Pascual, G; Rodríguez, M; Bellón, J M; Calvo, B

    2012-01-01

    Routine hernia repair surgery involves the implant of synthetic mesh. However, this type of procedure may give rise to pain and bowel incarceration and strangulation, causing considerable patient disability. The purpose of this study was to compare the long-term behaviour of three commercial meshes used to repair the partially herniated abdomen in New Zealand White rabbits: the heavyweight (HW) mesh, Surgipro(®) and lightweight (LW) mesh, Optilene(®), both made of polypropylene (PP), and a mediumweight (MW) mesh, Infinit(®), made of polytetrafluoroethylene (PTFE). The implanted meshes were mechanical and histological assessed at 14, 90 and 180 days post-implant. This behaviour was compared to the anisotropic mechanical behaviour of the unrepaired abdominal wall in control non-operated rabbits. Both uniaxial mechanical tests conducted in craneo-caudal and perpendicular directions and histological findings revealed substantial collagen growth over the repaired hernial defects causing stiffness in the repair zone, and thus a change in the original properties of the meshes. The mechanical behaviour of the healthy tissue in the craneo-caudal direction was not reproduced by any of the implanted meshes after 14 days or 90 days of implant, whereas in the perpendicular direction, SUR and OPT achieved similar behaviour. From a mechanical standpoint, the anisotropic PP-lightweight meshes may be considered a good choice in the long run, which correlates with the structure of the regenerated tissue. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Adaptive mesh generation for image registration and segmentation

    DEFF Research Database (Denmark)

    Fogtmann, Mads; Larsen, Rasmus

    2013-01-01

    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...

  3. Dynamic mesh for TCAD modeling with ECORCE

    Science.gov (United States)

    Michez, A.; Boch, J.; Touboul, A.; Saigné, F.

    2016-08-01

    Mesh generation for TCAD modeling is challenging. Because densities of carriers can change by several orders of magnitude in thin areas, a significant change of the solution can be observed for two very similar meshes. The mesh must be defined at best to minimize this change. To address this issue, a criterion based on polynomial interpolation on adjacent nodes is proposed that adjusts accurately the mesh to the gradients of Degrees of Freedom. Furthermore, a dynamic mesh that follows changes of DF in DC and transient mode is a powerful tool for TCAD users. But, in transient modeling, adding nodes to a mesh induces oscillations in the solution that appears as spikes at the current collected at the contacts. This paper proposes two schemes that solve this problem. Examples show that using these techniques, the dynamic mesh generator of the TCAD tool ECORCE handle semiconductors devices in DC and transient mode.

  4. SHARP/PRONGHORN Interoperability: Mesh Generation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Cluster parallel rendering based on encoded mesh

    Institute of Scientific and Technical Information of China (English)

    QIN Ai-hong; XIONG Hua; PENG Hao-yu; LIU Zhen; SHI Jiao-ying

    2006-01-01

    Use of compressed mesh in parallel rendering architecture is still an unexplored area, the main challenge of which is to partition and sort the encoded mesh in compression-domain. This paper presents a mesh compression scheme PRMC (Parallel Rendering based Mesh Compression) supplying encoded meshes that can be partitioned and sorted in parallel rendering system even in encoded-domain. First, we segment the mesh into submeshes and clip the submeshes' boundary into Runs, and then piecewise compress the submeshes and Runs respectively. With the help of several auxiliary index tables, compressed submeshes and Runs can serve as rendering primitives in parallel rendering system. Based on PRMC, we design and implement a parallel rendering architecture. Compared with uncompressed representation, experimental results showed that PRMC meshes applied in cluster parallel rendering system can dramatically reduce the communication requirement.

  6. Secure Mechanism for Handling Targeted Attacks in Infrastructure Based Wireless Mesh Networks

    Science.gov (United States)

    Shafi, Rehan; Rahim, Aneel; Bin Muhaya, Fahad; Ashraf, Shehzad; Sher, Muhammad

    Infrastructure based Wireless mesh networks allow heterogeneous types of networks to be connected at a time through wireless mesh routers. Since the nodes of every network have different processing power, bandwidth, amount of energy etc. so this situation can lead to targeted attacks. An Internet connected node can easily generate flood over a node of sensor network. So to handle these types of attacks we in this paper introduced a new secure authentication mechanism that works when a potential of attack is detected. Moreover we also authorized the nodes of the wireless mesh network to demand data according to their capacity by using pull data traffic control mechanism. We applied this solution first on mesh routers to discourage targeted attacks and secondly we applied the solution on an individual node that lies in between a node and mesh router.

  7. Coating with Autologous Plasma Improves Biocompatibility of Mesh Grafts In Vitro: Development Stage of a Surgical Innovation

    Directory of Open Access Journals (Sweden)

    Holger Gerullis

    2013-01-01

    Full Text Available Purpose. To investigate mesh coating modalities with autologous blood components in a recently developed in vitro test system for biocompatibility assessment of alloplastic materials. Materials and Methods. Seven different mesh types, currently used in various indications, were randomly investigated. Meshes were coated prior to cultivation with autologous peripheral blood mononuclear cells (PBMCs, platelets, and blood plasma. Pretreated meshes were incubated over 6 weeks in a minced tissue assay, representative for fibroblasts, muscle cells, and endothelial cells originating from 10 different patients. Adherence of those tissues on the meshes was microscopically investigated and semiquantitatively assessed using a previously described scoring system. Results. Coating with peripheral blood mononuclear cells did not affect the adherence score, whereas coating with platelets and blood plasma increased the score suggesting improved biocompatibility in vitro. The previous ranking of native meshes remained consistent after coating. Conclusion. Plasma coating of meshes improves their biocompatibility score in a novel in vitro test system.

  8. An in vitro study assessing the effect of mesh morphology and suture fixation on bacterial adherence.

    Science.gov (United States)

    Sanders, D; Lambie, J; Bond, P; Moate, R; Steer, J A

    2013-12-01

    Prosthetic infections, although relatively uncommon in hernia surgery, are a source of considerable morbidity and cost. The aims of this experimental study were to assess the influence of the morphological properties of the mesh on bacterial adherence in vitro. The morphological properties assessed were the polymer type, filament type, filament diameter, mesh weight, mean pore size, and the addition of silver chlorhexidine and titanium coatings. In addition, the study assessed the effect on bacterial adherence of adding a commonly used suture to the mesh and compared adherence rates to self-gripping mesh that does not require suture fixation. Eight commercially sourced flat hernia meshes with different material characteristics were included in the study. These were Prolene(®) (Ethicon(®)), DualMesh(®) (Gore(®)), DualMesh(®) Plus (Gore(®)), Parietex™ ProGrip (Covidien™), TiMesh(®) Light (GfE Medical), Bard(®) Soft Mesh (Bard(®)), Vypro(®) (Ethicon(®)), and Omyra(®) (Braun(®)). Individual meshes were inoculated with Staphylococcus epidermidis and Staphylococcus aureus with a bacterial inoculum of 10(2) bacteria. To assess the effect of suture material on bacterial adhesion, a sterile piece of commonly used monofilament suture material (2.0 Prolene(®), ZB370 Ethicon(®)) was sutured to selected meshes (chosen to represent different commonly used polymers and/or the presence of an antibacterial coating). Inoculated meshes were incubated for 18 h in tryptone soy broth and then analysed using scanning electron microscopy. A previously validated method for enumeration of bacteria using automated stage movement electron microscopy was used for direct bacterial counting. The final fraction of the bacteria adherent to the mesh was compared between the meshes and for each morphological variable. One-way analysis of variance (ANOVA) was performed on the bacterial counts. Tukey's test was used to determine the difference between the different biomaterials in

  9. Public health program planning logic model for community engaged type 2 diabetes management and prevention.

    Science.gov (United States)

    West, Joseph F

    2014-02-01

    Diabetes remains a growing epidemic with widening health inequity gaps in disease management, self-management knowledge, access to care and outcomes. Yet there is a paucity of evaluation tools for community engaged interventions aimed at closing the gaps and improving health. The Guide to Community Preventive Services (the Community Guide) developed by the Task Force on Community Preventive Services (the Task Force) at the Centers for Disease Control and Prevention (CDC) recommends two healthcare system level interventions, case management interventions and disease management programs, to improve glycemic control. However, as a public health resource guide for diabetes interventions a model for community engagement is a glaringly absent component of the Community Guide recommendations. In large part there are few evidence-based interventions featuring community engagement as a practice and system-level focus of chronic disease and Type 2 diabetes management. The central argument presented in this paper is that the absence of these types of interventions is due to the lack of tools for modeling and evaluating such interventions, especially among disparate and poor populations. A conceptual model emphasizing action-oriented micro-level community engagement is needed to complement the Community Guide and serve as the basis for testing and evaluation of these kinds of interventions. A unique logic model advancing the Community Guide diabetes recommendations toward measureable and sustainable community engagement for improved Type 2 diabetes outcomes is presented. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Synthetic Versus Biological Mesh-Related Erosion After Laparoscopic Ventral Mesh Rectopexy: A Systematic Review.

    Science.gov (United States)

    Balla, Andrea; Quaresima, Silvia; Smolarek, Sebastian; Shalaby, Mostafa; Missori, Giulia; Sileri, Pierpaolo

    2017-04-01

    This review reports the incidence of mesh-related erosion after ventral mesh rectopexy to determine whether any difference exists in the erosion rate between synthetic and biological mesh. A systematic search of the MEDLINE and the Ovid databases was conducted to identify suitable articles published between 2004 and 2015. The search strategy capture terms were laparoscopic ventral mesh rectopexy, laparoscopic anterior rectopexy, robotic ventral rectopexy, and robotic anterior rectopexy. Eight studies (3,956 patients) were included in this review. Of those patients, 3,517 patients underwent laparoscopic ventral rectopexy (LVR) using synthetic mesh and 439 using biological mesh. Sixty-six erosions were observed with synthetic mesh (26 rectal, 32 vaginal, 8 recto-vaginal fistulae) and one (perineal erosion) with biological mesh. The synthetic and the biological mesh-related erosion rates were 1.87% and 0.22%, respectively. The time between rectopexy and diagnosis of mesh erosion ranged from 1.7 to 124 months. No mesh-related mortalities were reported. The incidence of mesh-related erosion after LVR is low and is more common after the placement of synthetic mesh. The use of biological mesh for LVR seems to be a safer option; however, large, multicenter, randomized, control trials with long follow-ups are required if a definitive answer is to be obtained.

  11. Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo.

    Science.gov (United States)

    Ciritsis, Alexander; Horbach, Andreas; Staat, Manfred; Kuhl, Christiane K; Kraemer, Nils Andreas

    2017-04-07

    In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm(2) (± 5.7 cm(2) ) at 0 mmHg pneumoperitoneum and 274.6 cm(2) (± 5.2 cm(2) ) at 15 mmHg; for PVDF the mean areas were 205.5 cm(2) (± 8.8 cm(2) ) and 221.5 cm(2) (± 11.8 cm(2) ), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4% for TPU and of 1.2% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed

  12. Laparoscopic appendicectomy for suspected mesh-induced appendicitis after laparoscopic transabdominal preperitoneal polypropylene mesh inguinal herniorraphy

    Directory of Open Access Journals (Sweden)

    Jennings Jason

    2010-01-01

    Full Text Available Laparoscopic inguinal herniorraphy via a transabdominal preperitoneal (TAPP approach using Polypropylene Mesh (Mesh and staples is an accepted technique. Mesh induces a localised inflammatory response that may extend to, and involve, adjacent abdominal and pelvic viscera such as the appendix. We present an interesting case of suspected Mesh-induced appendicitis treated successfully with laparoscopic appendicectomy, without Mesh removal, in an elderly gentleman who presented with symptoms and signs of acute appendicitis 18 months after laparoscopic inguinal hernia repair. Possible mechanisms for Mesh-induced appendicitis are briefly discussed.

  13. Parallel-In-Time For Moving Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Falgout, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Manteuffel, T. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Southworth, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schroder, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-02-04

    With steadily growing computational resources available, scientists must develop e ective ways to utilize the increased resources. High performance, highly parallel software has be- come a standard. However until recent years parallelism has focused primarily on the spatial domain. When solving a space-time partial di erential equation (PDE), this leads to a sequential bottleneck in the temporal dimension, particularly when taking a large number of time steps. The XBraid parallel-in-time library was developed as a practical way to add temporal parallelism to existing se- quential codes with only minor modi cations. In this work, a rezoning-type moving mesh is applied to a di usion problem and formulated in a parallel-in-time framework. Tests and scaling studies are run using XBraid and demonstrate excellent results for the simple model problem considered herein.

  14. An effective quadrilateral mesh adaptation

    Institute of Scientific and Technical Information of China (English)

    KHATTRI Sanjay Kumar

    2006-01-01

    Accuracy of a simulation strongly depends on the grid quality. Here, quality means orthogonality at the boundaries and quasi-orthogonality within the critical regions, smoothness, bounded aspect ratios and solution adaptive behaviour. It is not recommended to refine the parts of the domain where the solution shows little variation. It is desired to concentrate grid points and cells in the part of the domain where the solution shows strong gradients or variations. We present a simple, effective and computationally efficient approach for quadrilateral mesh adaptation. Several numerical examples are presented for supporting our claim.

  15. Fabrication of silk mesh with enhanced cytocompatibility: preliminary in vitro investigation toward cell-based therapy for hernia repair.

    Science.gov (United States)

    Guillaume, O; Park, J; Monforte, X; Gruber-Blum, S; Redl, H; Petter-Puchner, A; Teuschl, A H

    2016-02-01

    Recent studies have demonstrated that combining cells with meshes prior to implantation successfully enhanced hernia repair. The idea is to create a biologic coating surrounding the mesh with autologous cells, before transplantation into the patient. However, due to the lack of a prompt and robust cell adhesion to the meshes, extensive in vitro cultivation is required to obtain a homogenous cell layer covering the mesh. In this context, the objective of this publication is to manufacture meshes made of silk fibres and to enhance the cytoadhesion and cytocompatibility of the biomaterial by surface immobilization of a pro-adhesive wheat germ agglutinin (lectin WGA). We first investigated the affinity between the glycoprotein WGA and cells, in solution and then after covalent immobilization of WGA on silk films. Then, we manufactured meshes made of silk fibres, tailored them with WGA grafting and finally evaluated the cytocompatibility and the inflammatory response of silk and silk-lectin meshes compared to common polypropylene mesh, using fibroblasts and peripheral blood mononuclear cells, respectively. The in vitro experiments revealed that the cytocompatibility of silk can be enhanced by surface immobilization with lectin WGA without exhibiting negative response in terms of pro-inflammatory reaction. Grafting lectin to silk meshes could bring advantages to facilitate cell-coating of meshes prior to implantation, which is an imperative prerequisite for abdominal wall tissue regeneration using cell-based therapy.

  16. Bluetooth Low Energy Mesh Networks: A Survey.

    Science.gov (United States)

    Darroudi, Seyed Mahdi; Gomez, Carles

    2017-06-22

    Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issues.

  17. Mesh networking optimized for robotic teleoperation

    Science.gov (United States)

    Hart, Abraham; Pezeshkian, Narek; Nguyen, Hoa

    2012-06-01

    Mesh networks for robot teleoperation pose different challenges than those associated with traditional mesh networks. Unmanned ground vehicles (UGVs) are mobile and operate in constantly changing and uncontrollable environments. Building a mesh network to work well under these harsh conditions presents a unique challenge. The Manually Deployed Communication Relay (MDCR) mesh networking system extends the range of and provides non-line-of-sight (NLOS) communications for tactical and explosive ordnance disposal (EOD) robots currently in theater. It supports multiple mesh nodes, robots acting as nodes, and works with all Internet Protocol (IP)-based robotic systems. Under MDCR, the performance of different routing protocols and route selection metrics were compared resulting in a modified version of the Babel mesh networking protocol. This paper discusses this and other topics encountered during development and testing of the MDCR system.

  18. MPDATA error estimator for mesh adaptivity

    Science.gov (United States)

    Szmelter, Joanna; Smolarkiewicz, Piotr K.

    2006-04-01

    In multidimensional positive definite advection transport algorithm (MPDATA) the leading error as well as the first- and second-order solutions are known explicitly by design. This property is employed to construct refinement indicators for mesh adaptivity. Recent progress with the edge-based formulation of MPDATA facilitates the use of the method in an unstructured-mesh environment. In particular, the edge-based data structure allows for flow solvers to operate on arbitrary hybrid meshes, thereby lending itself to implementations of various mesh adaptivity techniques. A novel unstructured-mesh nonoscillatory forward-in-time (NFT) solver for compressible Euler equations is used to illustrate the benefits of adaptive remeshing as well as mesh movement and enrichment for the efficacy of MPDATA-based flow solvers. Validation against benchmark test cases demonstrates robustness and accuracy of the approach.

  19. Bluetooth Low Energy Mesh Networks: A Survey

    Science.gov (United States)

    Darroudi, Seyed Mahdi; Gomez, Carles

    2017-01-01

    Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issues. PMID:28640183

  20. Mesh Location in Open Ventral Hernia Repair: A Systematic Review and Network Meta-analysis.

    Science.gov (United States)

    Holihan, Julie L; Nguyen, Duyen H; Nguyen, Mylan T; Mo, Jiandi; Kao, Lillian S; Liang, Mike K

    2016-01-01

    There is no consensus on the ideal location for mesh placement in open ventral hernia repair (OVHR). We aim to identify the mesh location associated with the lowest rate of recurrence following OVHR using a systematic review and meta-analysis. A search was performed for studies comparing at least two of four locations for mesh placement during OVHR (onlay, inlay, sublay, and underlay). Outcomes assessed were hernia recurrence and surgical site infection (SSI). Pairwise meta-analysis was performed to compare all direct treatment of mesh locations. A multiple treatment meta-analysis was performed to compare all mesh locations in the Bayesian framework. Sensitivity analyses were planned for the following: studies with a low risk of bias, incisional hernias, by hernia size, and by mesh type (synthetic or biologic). Twenty-one studies were identified (n = 5,891). Sublay placement of mesh was associated with the lowest risk for recurrence [OR 0.218 (95% CI 0.06-0.47)] and was the best of the four treatment modalities assessed [Prob (best) = 94.2%]. Sublay was also associated with the lowest risk for SSI [OR 0.449 (95% CI 0.12-1.16)] and was the best of the 4 treatment modalities assessed [Prob (best) = 77.3%]. When only assessing studies at low risk of bias, of incisional hernias, and using synthetic mesh, the probability that sublay had the lowest rate of recurrence and SSI was high. Sublay mesh location has lower complication rates than other mesh locations. While additional randomized controlled trials are needed to validate these findings, this network meta-analysis suggests the probability of sublay being the best location for mesh placement is high.

  1. Metal-Mesh Optical Filter Technology for Mid IR, Far IR, and Submillimeter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal describes a method of fabrication of far IR and THZ range multilayer metal-mesh filters. This type of filter consists of alternative...

  2. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  3. Delaunay triangulation and computational fluid dynamics meshes

    Science.gov (United States)

    Posenau, Mary-Anne K.; Mount, David M.

    1992-01-01

    In aerospace computational fluid dynamics (CFD) calculations, the Delaunay triangulation of suitable quadrilateral meshes can lead to unsuitable triangulated meshes. Here, we present case studies which illustrate the limitations of using structured grid generation methods which produce points in a curvilinear coordinate system for subsequent triangulations for CFD applications. We discuss conditions under which meshes of quadrilateral elements may not produce a Delaunay triangulation suitable for CFD calculations, particularly with regard to high aspect ratio, skewed quadrilateral elements.

  4. THM-GTRF: New Spider meshes, New Hydra-TH runs

    Energy Technology Data Exchange (ETDEWEB)

    Bakosi, Jozsef [Los Alamos National Laboratory; Christon, Mark A. [Los Alamos National Laboratory; Francois, Marianne M. [Los Alamos National Laboratory; Lowrie, Robert B. [Los Alamos National Laboratory; Nourgaliev, Robert [Los Alamos National Laboratory

    2012-06-20

    Progress is reported on computational capabilities for the grid-to-rod-fretting (GTRF) problem of pressurized water reactors. Numeca's Hexpress/Hybrid mesh generator is demonstrated as an excellent alternative to generating computational meshes for complex flow geometries, such as in GTRF. Mesh assessment is carried out using standard industrial computational fluid dynamics practices. Hydra-TH, a simulation code developed at LANL for reactor thermal-hydraulics, is demonstrated on hybrid meshes, containing different element types. A series of new Hydra-TH calculations has been carried out collecting turbulence statistics. Preliminary results on the newly generated meshes are discussed; full analysis will be documented in the L3 milestone, THM.CFD.P5.05, Sept. 2012.

  5. Box truss analysis and technology development. Task 1: Mesh analysis and control

    Science.gov (United States)

    Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.

    1985-01-01

    An analytical tool was developed to model, analyze and predict RF performance of box truss antennas with reflective mesh surfaces. The analysis system is unique in that it integrates custom written programs for cord tied mesh surfaces, thereby drastically reducing the cost of analysis. The analysis system is capable of determining the RF performance of antennas under any type of manufacturing or operating environment by integrating together the various disciplines of design, finite element analysis, surface best fit analysis and RF analysis. The Integrated Mesh Analysis System consists of six separate programs: The Mesh Tie System Model Generator, The Loadcase Generator, The Model Optimizer, The Model Solver, The Surface Topography Solver and The RF Performance Solver. Additionally, a study using the mesh analysis system was performed to determine the effect of on orbit calibration, i.e., surface adjustment, on a typical box truss antenna.

  6. Characteristics of copper meshes coated with carbon nanotubes via electrophoretic deposition

    Science.gov (United States)

    Kim, Bu-Jong; Park, Jong-Seol; Hwang, Young-Jin; Park, Jin-Seok

    2016-09-01

    This study demonstrates the characteristics of a hybrid-type transparent electrode for touch screen panels, which was fabricated by coating carbon nanotubes (CNTs) via electrophoretic deposition (EPD) on copper (Cu)-meshes. The surface morphologies, visible-range transmittance and reflectance, and chromatic properties, such as yellowness and redness, of the fabricated CNTs-coated Cu mesh electrodes were characterized as functions of their dimensions (line-to-line spacing, line width, and electrode thickness) and compared with those of the Cu-mesh electrodes without coating of CNTs. The experimental results showed that the coating of CNTs substantially reduced the reflectance of the Cu-mesh electrodes and also improved their chromatic properties with their transmittance and sheet resistance only slightly changed, subsequently indicating that the CNTs-coated Cu-mesh electrodes possessed desirable characteristics for touch screen panels.

  7. Design of electrospinning mesh devices

    Science.gov (United States)

    Russo, Giuseppina; Peters, Gerrit W. M.; Solberg, Ramon H. M.; Vittoria, Vittoria

    2012-07-01

    This paper describes the features of new membranes that can act as local biomedical devices owing to their peculiar shape in the form of mesh structure. These materials are designed to provide significant effects to reduce local inflammations and improve the tissue regeneration. Lamellar Hydrotalcite loaded with Diclofenac Sodium (HTLc-DIK) was homogenously dispersed inside a polymeric matrix of Poly-caprolactone (PCL) to manufacture membranes by electrospinning technique. The experimental procedure and the criteria employed have shown to be extremely effective at increasing potentiality and related applications. The employed technique has proved to be very useful to manufacture polymeric fibers with diameters in the range of nano-micro scale. In this work a dedicated collector based on a proprietary technology of IME Technologies and Eindhoven University of Technology (TU/e) was used. It allowed to obtain devices with a macro shape of a 3D-mesh. Atomic Force Microscopy (AFM) highlights a very interesting texture of the electrospun fibers. They show a lamellar morphology that is only slightly modified by the inclusion of the interclay embedded in the devices to control the drug release phenomena.

  8. Conformal refinement of unstructured quadrilateral meshes

    Energy Technology Data Exchange (ETDEWEB)

    Garmella, Rao [Los Alamos National Laboratory

    2009-01-01

    We present a multilevel adaptive refinement technique for unstructured quadrilateral meshes in which the mesh is kept conformal at all times. This means that the refined mesh, like the original, is formed of only quadrilateral elements that intersect strictly along edges or at vertices, i.e., vertices of one quadrilateral element do not lie in an edge of another quadrilateral. Elements are refined using templates based on 1:3 refinement of edges. We demonstrate that by careful design of the refinement and coarsening strategy, we can maintain high quality elements in the refined mesh. We demonstrate the method on a number of examples with dynamically changing refinement regions.

  9. Mesh Exposure and Associated Risk Factors in Women Undergoing Transvaginal Prolapse Repair with Mesh

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Frankman

    2013-01-01

    Full Text Available Objective. To determine frequency, rate, and risk factors associated with mesh exposure in women undergoing transvaginal prolapse repair with polypropylene mesh. Methods. Retrospective chart review was performed for all women who underwent Prolift Pelvic Floor Repair System (Gynecare, Somerville, NJ between September 2005 and September 2008. Multivariable logistic regression was performed to identify risk factors for mesh exposure. Results. 201 women underwent Prolift. Mesh exposure occurred in 12% (24/201. Median time to mesh exposure was 62 days (range: 10–372. When mesh was placed in the anterior compartment, the frequency of mesh exposure was higher than that when mesh was placed in the posterior compartment (8.7% versus 2.9%, P=0.04. Independent risk factors for mesh exposure were diabetes (AOR = 7.7, 95% CI 1.6–37.6; P=0.01 and surgeon (AOR = 7.3, 95% CI 1.9–28.6; P=0.004. Conclusion. Women with diabetes have a 7-fold increased risk for mesh exposure after transvaginal prolapse repair using Prolift. The variable rate of mesh exposure amongst surgeons may be related to technique. The anterior vaginal wall may be at higher risk of mesh exposure as compared to the posterior vaginal wall.

  10. Improving health services in developing countries with new types of public and allied health personnel.

    Science.gov (United States)

    Blayney, K D; Trulove, J W

    1982-10-01

    Allied health manpower in developing countries should be able to serve the specific needs of these countries in solving malnutrition, diarrheal disease, and other health problems. Disease patterns tend to evolve in stages with each stage requiring a special type of health manpower: 1) the 1st stage where infectious diseases are linked to poverty, malnutrition, and poor personal hygiene for which personnel trained to improve health through providing safe water supplies, improving sanitation, and immunizing the population are needed; 2) in the 2nd stages, diseases such as cancer, arthritis, and cardiac diseases exist, requiring extensive technology such as is available in the US; and 3) the 3rd stage relates to an awareness of health hazards (caused by the environment, by the lifestyle dysfunctions of the society, and an emphasis on health promotion) and implies a responsibility for one's own health by the individual; this is a difficult stage to apply to developing countries since the ability to bring about change assumes literacy on the part of the population which is not always the case. Since most developing countries need to cause change in the 1st stage, more public health personnel such as sanitarians and generalist workers are needed. Training of these personnel should include on-the-job education; traditionally trained US allied health professionals are not always equipped to deal with health problems in developing countries. Health educators should look to the lessons learned by the US in the allied health movement: 1) the system of control that national membership organizations have over schooling and the job environment has contributed to an increased cost of health care delivery, unnecessary prolonged curricula, overspecialization, extreme protectionism for membership, and inappropriate fractionalization of health care delivery; 2) the emphasis on prolonged curricula sometimes causes the student to lose sight of the supposed direct relationship between

  11. Missing Citations, Bulking Biographies, and Unethical Collaboration: Types of Cheating among Public Relations Majors

    Science.gov (United States)

    Auger, Giselle A.

    2013-01-01

    Students cheat. For the field of public relations, which continually struggles for credibility, the issue of student cheating should be paramount, as the unethical students of today become tomorrow's practitioners. Through a survey of 170 public relations majors, this study examined the importance students place on the Public Relations Society of…

  12. Missing Citations, Bulking Biographies, and Unethical Collaboration: Types of Cheating among Public Relations Majors

    Science.gov (United States)

    Auger, Giselle A.

    2013-01-01

    Students cheat. For the field of public relations, which continually struggles for credibility, the issue of student cheating should be paramount, as the unethical students of today become tomorrow's practitioners. Through a survey of 170 public relations majors, this study examined the importance students place on the Public Relations Society of…

  13. Security Routing Protocol For The Wireless Mesh Networks (WMNs)

    Institute of Scientific and Technical Information of China (English)

    王五妹; 赵彩丹; 黄联芬; 姚彦

    2008-01-01

    The pretty promising Wireless Mesh Networking technique, which is regarded as the next generation wireless Internet, not only possesses the normal features of wireless networks, but also has the advantages of multi-hop, self-organizing, etc. However, the great strength of the Mesh Networks also lead to a serious problem in the perspective of network security. This paper starts with the security issue of WMN routing and puts forward the corresponding solutions to the two kinds of routings’ security, such as adding the public/private (Pi/Si) key to the AODV to solve the problem of black hole and adding the credit value of nodes to the DSR to improve the security.

  14. Adaptive mesh refinement in titanium

    Energy Technology Data Exchange (ETDEWEB)

    Colella, Phillip; Wen, Tong

    2005-01-21

    In this paper, we evaluate Titanium's usability as a high-level parallel programming language through a case study, where we implement a subset of Chombo's functionality in Titanium. Chombo is a software package applying the Adaptive Mesh Refinement methodology to numerical Partial Differential Equations at the production level. In Chombo, the library approach is used to parallel programming (C++ and Fortran, with MPI), whereas Titanium is a Java dialect designed for high-performance scientific computing. The performance of our implementation is studied and compared with that of Chombo in solving Poisson's equation based on two grid configurations from a real application. Also provided are the counts of lines of code from both sides.

  15. Mesh refinement strategy for optimal control problems

    Science.gov (United States)

    Paiva, L. T.; Fontes, F. A. C. C.

    2013-10-01

    Direct methods are becoming the most used technique to solve nonlinear optimal control problems. Regular time meshes having equidistant spacing are frequently used. However, in some cases these meshes cannot cope accurately with nonlinear behavior. One way to improve the solution is to select a new mesh with a greater number of nodes. Another way, involves adaptive mesh refinement. In this case, the mesh nodes have non equidistant spacing which allow a non uniform nodes collocation. In the method presented in this paper, a time mesh refinement strategy based on the local error is developed. After computing a solution in a coarse mesh, the local error is evaluated, which gives information about the subintervals of time domain where refinement is needed. This procedure is repeated until the local error reaches a user-specified threshold. The technique is applied to solve the car-like vehicle problem aiming minimum consumption. The approach developed in this paper leads to results with greater accuracy and yet with lower overall computational time as compared to using a time meshes having equidistant spacing.

  16. 7th International Meshing Roundtable '98

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, T.J.

    1998-10-01

    The goal of the 7th 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 past, the Roundtable has enjoyed significant participation from each of these groups from a wide variety of countries.

  17. Laparoscopic Pelvic Floor Repair Using Polypropylene Mesh

    Directory of Open Access Journals (Sweden)

    Shih-Shien Weng

    2008-09-01

    Conclusion: Laparoscopic pelvic floor repair using a single piece of polypropylene mesh combined with uterosacral ligament suspension appears to be a feasible procedure for the treatment of advanced vaginal vault prolapse and enterocele. Fewer mesh erosions and postoperative pain syndromes were seen in patients who had no previous pelvic floor reconstructive surgery.

  18. On the application of hybrid meshes in hydraulic machinery CFD simulations

    Science.gov (United States)

    Schlipf, M.; Tismer, A.; Riedelbauch, S.

    2016-11-01

    The application of two different hybrid mesh types for the simulation of a Francis runner for automated optimization processes without user input is investigated. Those mesh types are applied to simplified test cases such as flow around NACA airfoils to identify the special mesh resolution effects with reduced complexity, like rotating cascade flows, as they occur in a turbomachine runner channel. The analysis includes the application of those different meshes on the geometries by keeping defined quality criteria and exploring the influences on the simulation results. All results are compared with reference values gained by simulations with blockstructured hexahedron meshes and the same numerical scheme. This avoids additional inaccuracies caused by further numerical and experimental measurement methods. The results show that a simulation with hybrid meshes built up by a blockstructured domain with hexahedrons around the blade in combination with a tetrahedral far field in the channel is sufficient to get results which are almost as accurate as the results gained by the reference simulation. Furthermore this method is robust enough for automated processes without user input and enables comparable meshes in size, distribution and quality for different similar geometries as occurring in optimization processes.

  19. A comparison of tetrahedral mesh improvement techniques

    Energy Technology Data Exchange (ETDEWEB)

    Freitag, L.A.; Ollivier-Gooch, C. [Argonne National Lab., IL (United States). Mathematics and Computer Science Div.

    1996-12-01

    Automatic mesh generation and adaptive refinement methods for complex three-dimensional domains have proven to be very successful tools for the efficient solution of complex applications problems. These methods can, however, produce poorly shaped elements that cause the numerical solution to be less accurate and more difficult to compute. Fortunately, the shape of the elements can be improved through several mechanisms, including face-swapping techniques that change local connectivity and optimization-based mesh smoothing methods that adjust grid point location. The authors consider several criteria for each of these two methods and compare the quality of several meshes obtained by using different combinations of swapping and smoothing. Computational experiments show that swapping is critical to the improvement of general mesh quality and that optimization-based smoothing is highly effective in eliminating very small and very large angles. The highest quality meshes are obtained by using a combination of swapping and smoothing techniques.

  20. Comparative study on triangular and quadrilateral meshes by a finite-volume method with a central difference scheme

    KAUST Repository

    Yu, Guojun

    2012-10-01

    In this article, comparative studies on computational accuracies and convergence rates of triangular and quadrilateral meshes are carried out in the frame work of the finite-volume method. By theoretical analysis, we conclude that the number of triangular cells needs to be 4/3 times that of quadrilateral cells to obtain similar accuracy. The conclusion is verified by a number of numerical examples. In addition, the convergence rates of the triangular meshes are found to be slower than those of the quadrilateral meshes when the same accuracy is obtained with these two mesh types. © 2012 Taylor and Francis Group, LLC.

  1. Method for generating a mesh representation of a region characterized by a trunk and a branch thereon

    Science.gov (United States)

    Shepherd, Jason; Mitchell, Scott A.; Jankovich, Steven R.; Benzley, Steven E.

    2007-05-15

    The present invention provides a meshing method, called grafting, that lifts the prior art constraint on abutting surfaces, including surfaces that are linking, source/target, or other types of surfaces of the trunk volume. The grafting method locally modifies the structured mesh of the linking surfaces allowing the mesh to conform to additional surface features. Thus, the grafting method can provide a transition between multiple sweep directions extending sweeping algorithms to 23/4-D solids. The method is also suitable for use with non-sweepable volumes; the method provides a transition between meshes generated by methods other than sweeping as well.

  2. Characteristics of Mesh Wave Impedance in FDTD Non-Uniform Mesh

    Institute of Scientific and Technical Information of China (English)

    REN Wu; LIU Bo; GAO Ben-qing

    2005-01-01

    In order to increase the evaluating precision of mesh reflection wave, the mesh wave impedance(MWI) is extended to the non-uniform mesh in 1-D and 2-D cases for the first time on the basis of the Yee's positional relation for electromagnetic field components. Lots of characteristics are obtained for different mesh sizes and frequencies. Then the reflection coefficient caused by the non-uniform mesh can be calculated according to the theory of equivalent transmission line. By comparing it with that calculated by MWI in the uniform mesh, it is found that the evaluating error can be largely reduced and is in good agreement with that directly computed by FDTD method. And this extension of MWI can be used in the error analysis of complex mesh.

  3. Update on Development of Mesh Generation Algorithms in MeshKit

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Type, frequency and purpose of information used to inform public health policy and program decision-making.

    Science.gov (United States)

    Zardo, Pauline; Collie, Alex

    2015-04-15

    There is a growing demand for researchers to document the impact of research to demonstrate how it contributes to community outcomes. In the area of public health it is expected that increases in the use of research to inform policy and program development will lead to improved public health outcomes. To determine whether research has an impact on public health outcomes, we first need to assess to what extent research has been used and how it has been used. However, there are relatively few studies to date that have quantitatively measured the extent and purpose of use of research in public health policy environments. This study sought to quantitatively measure the frequency and purpose of use of research evidence in comparison to use of other information types in a specific public health policy environment, workplace and transport injury prevention and rehabilitation compensation. A survey was developed to measure the type, frequency and purpose of information used to inform policy and program decision-making. Research evidence was the type of information used least frequently and internal data and reports was the information type used most frequently. Findings also revealed differences in use of research between and within the two government public health agencies studied. In particular the main focus of participants' day-to-day role was associated with the type of information used. Research was used mostly for conceptual purposes. Interestingly, research was used for instrumental purposes more often than it was used for symbolic purposes, which is contrary to findings of previous research. These results have implications for the design and implementation of research translation interventions in the context within which the study was undertaken. In particular, they suggest that intervention will need to be targeted to the information needs of the different role groups within an organisation. The results can also be utilised as a baseline measure for intervention

  5. Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems

    Science.gov (United States)

    Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John

    2010-01-01

    Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.

  6. RICH: Open-source Hydrodynamic Simulation on a Moving Voronoi Mesh

    Science.gov (United States)

    Yalinewich, Almog; Steinberg, Elad; Sari, Re'em

    2015-02-01

    We present here RICH, a state-of-the-art two-dimensional hydrodynamic code based on Godunov’s method, on an unstructured moving mesh (the acronym stands for Racah Institute Computational Hydrodynamics). This code is largely based on the code AREPO. It differs from AREPO in the interpolation and time-advancement schemeS as well as a novel parallelization scheme based on Voronoi tessellation. Using our code, we study the pros and cons of a moving mesh (in comparison to a static mesh). We also compare its accuracy to other codes. Specifically, we show that our implementation of external sources and time-advancement scheme is more accurate and robust than is AREPO when the mesh is allowed to move. We performed a parameter study of the cell rounding mechanism (Lloyd iterations) and its effects. We find that in most cases a moving mesh gives better results than a static mesh, but it is not universally true. In the case where matter moves in one way and a sound wave is traveling in the other way (such that relative to the grid the wave is not moving) a static mesh gives better results than a moving mesh. We perform an analytic analysis for finite difference schemes that reveals that a Lagrangian simulation is better than a Eulerian simulation in the case of a highly supersonic flow. Moreover, we show that Voronoi-based moving mesh schemes suffer from an error, which is resolution independent, due to inconsistencies between the flux calculation and the change in the area of a cell. Our code is publicly available as open source and designed in an object-oriented, user-friendly way that facilitates incorporation of new algorithms and physical processes.

  7. Note: Radial-thrust combo metal mesh foil bearing for microturbomachinery.

    Science.gov (United States)

    Park, Cheol Hoon; Choi, Sang Kyu; Hong, Doo Euy; Yoon, Tae Gwang; Lee, Sung Hwi

    2013-10-01

    This Note proposes a novel radial-thrust combo metal mesh foil bearing (MMFB). Although MMFBs have advantages such as higher stiffness and damping over conventional air foil bearings, studies related to MMFBs have been limited to radial MMFBs. The novel combo MMFB is composed of a radial top foil, thrust top foils, and a ring-shaped metal mesh damper--fabricated by compressing a copper wire mesh--with metal mesh thrust pads for the thrust bearing at both side faces. In this study, the combo MMFB was fabricated in half-split type to support the rotor for a micro gas turbine generator. The manufacture and assembly process for the half-split-type combo MMFB is presented. In addition, to verify the proposed combo MMFB, motoring test results up to 250,000 rpm and axial displacements as a function of rotational speed are presented.

  8. Quadratically consistent projection from particles to mesh

    CERN Document Server

    Duque, Daniel

    2016-01-01

    The advantage of particle Lagrangian methods in computational fluid dynamics is that advection is accurately modeled. However, this complicates the calculation of space derivatives. If a mesh is employed, it must be updated at each time step. On the other hand, fixed mesh, Eulerian, formulations benefit from the mesh being defined at the beginning of the simulation, but feature non-linear advection terms. It therefore seems natural to combine the two approaches, using a fixed mesh to perform calculations related to space derivatives, and using the particles to advect the information with time. The idea of combining Lagrangian particles and a fixed mesh goes back to Particle-in-Cell methods, and is here considered within the context of the finite element method (FEM) for the fixed mesh, and the particle FEM (pFEM) for the particles. Our results, in agreement with recent works, show that interpolation ("projection") errors, especially from particles to mesh, are the culprits of slow convergence of the method if...

  9. [The ultrasound semiotics of uncomplicated wound healing after inguinal mesh plastics].

    Science.gov (United States)

    Kharitonov, S V; Ziniakova, M V

    2012-01-01

    Dynamic ultrasound (US) investigation was performed in 89 patients operated on inguinal hernia with the use of meshes of various type. The US scanning proved to be a highly informative means of visualization, allowing the objective postoperative assessment of muscular and aponeurotic structures as well as the implant form and position. The study showed, that the mesh implantation was always accompanied by the exudative tissue reaction, which was determined by the physico-chemical characteristics of the implant.

  10. Protected area types, strategies and impacts in Brazil's Amazon: public protected area strategies do not yield a consistent ranking of protected area types by impact.

    Science.gov (United States)

    Pfaff, Alexander; Robalino, Juan; Sandoval, Catalina; Herrera, Diego

    2015-11-05

    The leading policy to conserve forest is protected areas (PAs). Yet, PAs are not a single tool: land users and uses vary by PA type; and public PA strategies vary in the extent of each type and in the determinants of impact for each type, i.e. siting and internal deforestation. Further, across regions and time, strategies respond to pressures (deforestation and political). We estimate deforestation impacts of PA types for a critical frontier, the Brazilian Amazon. We separate regions and time periods that differ in their deforestation and political pressures and document considerable variation in PA strategies across regions, time periods and types. The siting of PAs varies across regions. For example, all else being equal, PAs in the arc of deforestation are relatively far from non-forest, while in other states they are relatively near. Internal deforestation varies across time periods, e.g. it is more similar across the PA types for PAs after 2000. By contrast, after 2000, PA extent is less similar across PA types with little non-indigenous area created inside the arc. PA strategies generate a range of impacts for PA types--always far higher within the arc--but not a consistent ranking of PA types by impact. © 2015 The Author(s).

  11. Mesh optimization for microbial fuel cell cathodes constructed around stainless steel mesh current collectors

    KAUST Repository

    Zhang, Fang

    2011-02-01

    Mesh current collectors made of stainless steel (SS) can be integrated into microbial fuel cell (MFC) cathodes constructed of a reactive carbon black and Pt catalyst mixture and a poly(dimethylsiloxane) (PDMS) diffusion layer. It is shown here that the mesh properties of these cathodes can significantly affect performance. Cathodes made from the coarsest mesh (30-mesh) achieved the highest maximum power of 1616 ± 25 mW m-2 (normalized to cathode projected surface area; 47.1 ± 0.7 W m-3 based on liquid volume), while the finest mesh (120-mesh) had the lowest power density (599 ± 57 mW m-2). Electrochemical impedance spectroscopy showed that charge transfer and diffusion resistances decreased with increasing mesh opening size. In MFC tests, the cathode performance was primarily limited by reaction kinetics, and not mass transfer. Oxygen permeability increased with mesh opening size, accounting for the decreased diffusion resistance. At higher current densities, diffusion became a limiting factor, especially for fine mesh with low oxygen transfer coefficients. These results demonstrate the critical nature of the mesh size used for constructing MFC cathodes. © 2010 Elsevier B.V. All rights reserved.

  12. Non-conforming hybrid meshes for efficient 2-D wave propagation using the Discontinuous Galerkin Method

    Science.gov (United States)

    Hermann, Verena; Käser, Martin; Castro, Cristóbal E.

    2011-02-01

    We present a Discontinuous Galerkin finite element method using a high-order time integration technique for seismic wave propagation modelling on non-conforming hybrid meshes in two space dimensions. The scheme can be formulated to achieve the same approximation order in space and time and avoids numerical artefacts due to non-conforming mesh transitions or the change of the element type. A point-wise Gaussian integration along partially overlapping edges of adjacent elements is used to preserve the schemes accuracy while providing a higher flexibility in the problem-adapted mesh generation process. We describe the domain decomposition strategy of the parallel implementation and validate the performance of the new scheme by numerical convergence test and experiments with comparisons to independent reference solutions. The advantage of non-conforming hybrid meshes is the possibility to choose the mesh spacing proportional to the seismic velocity structure, which allows for simple refinement or coarsening methods even for regular quadrilateral meshes. For particular problems of strong material contrasts and geometrically thin structures, the scheme reduces the computational cost in the sense of memory and run-time requirements. The presented results promise to achieve a similar behaviour for an extension to three space dimensions where the coupling of tetrahedral and hexahedral elements necessitates non-conforming mesh transitions to avoid linking elements in form of pyramids.

  13. Generation of high order geometry representations in Octree meshes

    Directory of Open Access Journals (Sweden)

    Harald G. Klimach

    2015-11-01

    Full Text Available We propose a robust method to convert triangulated surface data into polynomial volume data. Such polynomial representations are required for high-order partial differential solvers, as low-order surface representations would diminish the accuracy of their solution. Our proposed method deploys a first order spatial bisection algorithm to find robustly an approximation of given geometries. The resulting voxelization is then used to generate Legendre polynomials of arbitrary degree. By embedding the locally defined polynomials in cubical elements of a coarser mesh, this method can reliably approximate even complex structures, like porous media. It thereby is possible to provide appropriate material definitions for high order discontinuous Galerkin schemes. We describe the method to construct the polynomial and how it fits into the overall mesh generation. Our discussion includes numerical properties of the method and we show some results from applying it to various geometries. We have implemented the described method in our mesh generator Seeder, which is publically available under a permissive open-source license.

  14. H(curl) Auxiliary Mesh Preconditioning

    Energy Technology Data Exchange (ETDEWEB)

    Kolev, T V; Pasciak, J E; Vassilevski, P S

    2006-08-31

    This paper analyzes a two-level preconditioning scheme for H(curl) bilinear forms. The scheme utilizes an auxiliary problem on a related mesh that is more amenable for constructing optimal order multigrid methods. More specifically, we analyze the case when the auxiliary mesh only approximately covers the original domain. The latter assumption is important since it allows for easy construction of nested multilevel spaces on regular auxiliary meshes. Numerical experiments in both two and three space dimensions illustrate the optimal performance of the method.

  15. Engagement of Metal Debris into Gear Mesh

    Science.gov (United States)

    handschuh, Robert F.; Krantz, Timothy L.

    2010-01-01

    A series of bench-top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

  16. Application of mesh network radios to UGS

    Science.gov (United States)

    Calcutt, Wade; Jones, Barry; Roeder, Brent

    2008-04-01

    During the past five years McQ has been actively pursuing integrating and applying wireless mesh network radios as a communications solution for unattended ground sensor (UGS) systems. This effort has been rewarded with limited levels of success and has ultimately resulted in a corporate position regarding the use of mesh network radios for UGS systems. A discussion into the background of the effort, the challenges of implementing commercial off-the-shelf (COTS) mesh radios with UGSs, the tradeoffs involved, and an overview of the future direction is presented.

  17. Mesh Optimization for Ground Vehicle Aerodynamics

    OpenAIRE

    Adrian Gaylard; Essam F Abo-Serie; Nor Elyana Ahmad

    2010-01-01

    Mesh optimization strategy for estimating accurate drag of a ground vehicle is proposed based on examining the effect of different mesh parameters.  The optimized mesh parameters were selected using design of experiment (DOE) method to be able to work in a...

  18. Rigidity Constraints for Large Mesh Deformation

    Institute of Scientific and Technical Information of China (English)

    Yong Zhao; Xin-Guo Liu; Qun-Sheng Peng; Hu-Jun Bao

    2009-01-01

    It is a challenging problem of surface-based deformation to avoid apparent volumetric distortions around largely deformed areas. In this paper, we propose a new rigidity constraint for gradient domain mesh deformation to address this problem. Intuitively the proposed constraint can be regarded as several small cubes defined by the mesh vertices through mean value coordinates. The user interactively specifies the cubes in the regions which are prone to volumetric distortions, and the rigidity constraints could make the mesh behave like a solid object during deformation. The experimental results demonstrate that our constraint is intuitive, easy to use and very effective.

  19. SURFACE MESH PARAMETERIZATION WITH NATURAL BOUNDARY

    Institute of Scientific and Technical Information of China (English)

    Ye Ming; Zhu Xiaofeng; Wang Chengtao

    2003-01-01

    Using the projected curve of surface mesh boundary as parameter domain border, linear mapping parameterization with natural boundary is realized. A fast algorithm for least squares fitting plane of vertices in the mesh boundary is proposed. After the mesh boundary is projected onto the fitting plane, low-pass filtering is adopted to eliminate crossovers, sharp corners and cavities in the projected curve and convert it into an eligible convex parameter domain boundary. In order to facilitate quantitative evaluations of parameterization schemes, three distortion-measuring formulae are presented.

  20. Gear Mesh Loss-of-Lubrication Experiments and Analytical Simulation

    Science.gov (United States)

    Handschuh, Robert F.; Polly, Joseph; Morales, Wilfredo

    2011-01-01

    An experimental program to determine the loss-of-lubrication (LOL) characteristics of spur gears in an aerospace simulation test facility has been completed. Tests were conducted using two different emergency lubricant types: (1) an oil mist system (two different misted lubricants) and (2) a grease injection system (two different grease types). Tests were conducted using a NASA Glenn test facility normally used for conducting contact fatigue. Tests were run at rotational speeds up to 10000 rpm using two different gear designs and two different gear materials. For the tests conducted using an air-oil misting system, a minimum lubricant injection rate was determined to permit the gear mesh to operate without failure for at least 1 hr. The tests allowed an elevated steady state temperature to be established. A basic 2-D heat transfer simulation has been developed to investigate temperatures of a simulated gear as a function of frictional behavior. The friction (heat generation source) between the meshing surfaces is related to the position in the meshing cycle, the load applied, and the amount of lubricant in the contact. Experimental conditions will be compared to those from the 2-D simulation.

  1. Key technologies for high-accuracy large mesh antenna reflectors

    Science.gov (United States)

    Meguro, Akira; Harada, Satoshi; Watanabe, Mitsunobu

    2003-12-01

    Nippon Telephone and Telegram Corporation (NTT) continues to develop the modular mesh-type deployable antenna. Antenna diameter can be changed from 5 m to about 20 m by changing the number of modules used with surface accuracy better than 2.4 mm RMS (including all error factors) with sufficient deployment reliability. Key technologies are the antenna's structural design, the deployment mechanism, the design tool, the analysis tool, and modularized testing/evaluation methods. This paper describes our beam steering mechanism. Tests show that it yields a beam pointing accuracy of better than 0.1°. Based on the S-band modular mesh antenna reflector, the surface accuracy degradation factors that must be considered in designing the new antenna are partially identified. The influence of modular connection errors on surface accuracy is quantitatively estimated. Our analysis tool SPADE is extended to include the addition of joint gaps. The addition of gaps allows non-linear vibration characteristics due to gapping in deployment hinges to be calculated. We intend to design a new type of mesh antenna reflector. Our new goal is an antenna for Ku or Ka band satellite communication. For this mission, the surface shape must be 5 times more accurate than is required for an S-band antenna.

  2. Smooth Rotation Enhanced As-Rigid-As-Possible Mesh Animation.

    Science.gov (United States)

    Levi, Zohar; Gotsman, Craig

    2015-02-01

    In recent years, the As-Rigid-As-Possible (ARAP) shape deformation and shape interpolation techniques gained popularity, and the ARAP energy was successfully used in other applications as well. We improve the ARAP animation technique in two aspects. First, we introduce a new ARAP-type energy, named SR-ARAP, which has a consistent discretization for surfaces (triangle meshes). The quality of our new surface deformation scheme competes with the quality of the volumetric ARAP deformation (for tetrahedral meshes). Second, we propose a new ARAP shape interpolation method that is superior to prior art also based on the ARAP energy. This method is compatible with our new SR-ARAP energy, as well as with the ARAP volume energy.

  3. MAC layer security issues in wireless mesh networks

    Science.gov (United States)

    Reddy, K. Ganesh; Thilagam, P. Santhi

    2016-03-01

    Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

  4. Analysis of the Numerical Diffusion in Anisotropic Mediums: Benchmarks for Magnetic Field Aligned Meshes in Space Propulsion Simulations

    Directory of Open Access Journals (Sweden)

    Daniel Pérez-Grande

    2016-11-01

    Full Text Available This manuscript explores numerical errors in highly anisotropic diffusion problems. First, the paper addresses the use of regular structured meshes in numerical solutions versus meshes aligned with the preferential directions of the problem. Numerical diffusion in structured meshes is quantified by solving the classical anisotropic diffusion problem; the analysis is exemplified with the application to a numerical model of conducting fluids under magnetic confinement, where rates of transport in directions parallel and perpendicular to a magnetic field are quite different. Numerical diffusion errors in this problem promote the use of magnetic field aligned meshes (MFAM. The generation of this type of meshes presents some challenges; several meshing strategies are implemented and analyzed in order to provide insight into achieving acceptable mesh regularity. Second, Gradient Reconstruction methods for magnetically aligned meshes are addressed and numerical errors are compared for the structured and magnetically aligned meshes. It is concluded that using the latter provides a more correct and straightforward approach to solving problems where anisotropicity is present, especially, if the anisotropicity level is high or difficult to quantify. The conclusions of the study may be extrapolated to the study of anisotropic flows different from conducting fluids.

  5. Optimisation of mesh enclosures for nursery rearing of juvenile sea cucumbers.

    Science.gov (United States)

    Purcell, Steven W; Agudo, Natacha S

    2013-01-01

    Mariculture of tropical sea cucumbers is promising, but the nursery rearing of juveniles is a bottleneck for farming and sea ranching. We conducted four medium-scale experiments lasting 3-6 weeks, using thousands of cultured juvenile sandfish Holothuria scabra, to optimise nursery rearing in mesh enclosures in earthen seawater ponds and to test rearing in enclosures in the sea. In one experiment, survival in fine-mesh enclosures (1 m(3); 660-µm mesh) related nonlinearly to juvenile size, revealing a threshold body length of 5-8 mm for initial transfer from hatchery tanks. Survival in enclosures within ponds in the other experiments ranged from 78-97%, and differences in growth rates among experiments were explained largely by seasonal differences in seawater temperatures in ponds. Stripped shadecloth units within fine-mesh enclosures increased feeding surfaces and improved growth rates by >15%. On the other hand, shading over the enclosures may lower growth rates. Following the rearing in fine-mesh enclosures, small juveniles (0.5 to 1 g) were grown to stocking size (3-10 g) in coarse-mesh enclosures of 1-mm mesh. Sand or mud added to coarse-mesh enclosures did not significantly improve growth compared to controls without sediment. Survival of sandfish juveniles in coarse-mesh enclosures set on the benthos within seagrass beds differed between two sheltered bays and growth was slow compared to groups within the same type of enclosures in an earthen pond. Our findings should lead to significant improvement in the cost-effectiveness of rearing sandfish juveniles to a stocking size compared to established methods and highlight the need for further research into nursery systems in the sea.

  6. Assignment of fields from particles to mesh

    CERN Document Server

    Duque, Daniel

    2016-01-01

    In Computational Fluid Dynamics there have been many attempts to combine the power of a fixed mesh on which to carry out spatial calculations with that of a set of particles that moves following the velocity field. These ideas indeed go back to Particle-in-Cell methods, proposed about 60 years ago. Of course, some procedure is needed to transfer field information between particles and mesh. There are many possible choices for this "assignment", or "projection". Several requirements may guide this choice. Two well-known ones are conservativity and stability, which apply to volume integrals of the fields. An additional one is here considered: preservation of information. This means that mesh interpolation, followed by mesh assignment, should leave the field values invariant. The resulting methods are termed "mass" assignments due to their strong similarities with the Finite Element Method. We test several procedures, including the well-known FLIP, on three scenarios: simple 1D convection, 2D convection of Zales...

  7. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang

    2011-01-01

    We present a general computational framework to locally characterize any shape space of meshes implicitly prescribed by a collection of non-linear constraints. We computationally access such manifolds, typically of high dimension and co-dimension, through first and second order approximants, namely tangent spaces and quadratically parameterized osculant surfaces. Exploration and navigation of desirable subspaces of the shape space with regard to application specific quality measures are enabled using approximants that are intrinsic to the underlying manifold and directly computable in the parameter space of the osculant surface. We demonstrate our framework on shape spaces of planar quad (PQ) meshes, where each mesh face is constrained to be (nearly) planar, and circular meshes, where each face has a circumcircle. We evaluate our framework for navigation and design exploration on a variety of inputs, while keeping context specific properties such as fairness, proximity to a reference surface, etc.

  8. LR: Compact connectivity representation for triangle meshes

    Energy Technology Data Exchange (ETDEWEB)

    Gurung, T; Luffel, M; Lindstrom, P; Rossignac, J

    2011-01-28

    We propose LR (Laced Ring) - a simple data structure for representing the connectivity of manifold triangle meshes. LR provides the option to store on average either 1.08 references per triangle or 26.2 bits per triangle. Its construction, from an input mesh that supports constant-time adjacency queries, has linear space and time complexity, and involves ordering most vertices along a nearly-Hamiltonian cycle. LR is best suited for applications that process meshes with fixed connectivity, as any changes to the connectivity require the data structure to be rebuilt. We provide an implementation of the set of standard random-access, constant-time operators for traversing a mesh, and show that LR often saves both space and traversal time over competing representations.

  9. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang

    2011-12-12

    We present a general computational framework to locally characterize any shape space of meshes implicitly prescribed by a collection of non-linear constraints. We computationally access such manifolds, typically of high dimension and co-dimension, through first and second order approximants, namely tangent spaces and quadratically parameterized osculant surfaces. Exploration and navigation of desirable subspaces of the shape space with regard to application specific quality measures are enabled using approximants that are intrinsic to the underlying manifold and directly computable in the parameter space of the osculant surface. We demonstrate our framework on shape spaces of planar quad (PQ) meshes, where each mesh face is constrained to be (nearly) planar, and circular meshes, where each face has a circumcircle. We evaluate our framework for navigation and design exploration on a variety of inputs, while keeping context specific properties such as fairness, proximity to a reference surface, etc. © 2011 ACM.

  10. Spacetime Meshing for Discontinuous Galerkin Methods

    CERN Document Server

    Thite, Shripad Vidyadhar

    2008-01-01

    Spacetime discontinuous Galerkin (SDG) finite element methods are used to solve such PDEs involving space and time variables arising from wave propagation phenomena in important applications in science and engineering. To support an accurate and efficient solution procedure using SDG methods and to exploit the flexibility of these methods, we give a meshing algorithm to construct an unstructured simplicial spacetime mesh over an arbitrary simplicial space domain. Our algorithm is the first spacetime meshing algorithm suitable for efficient solution of nonlinear phenomena in anisotropic media using novel discontinuous Galerkin finite element methods for implicit solutions directly in spacetime. Given a triangulated d-dimensional Euclidean space domain M (a simplicial complex) and initial conditions of the underlying hyperbolic spacetime PDE, we construct an unstructured simplicial mesh of the (d+1)-dimensional spacetime domain M x [0,infinity). Our algorithm uses a near-optimal number of spacetime elements, ea...

  11. Metal Mesh Filters for Terahertz Receivers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objective of this SBIR program is to develop and demonstrate metal mesh filters for use in NASA's low noise receivers for terahertz astronomy and...

  12. Adaptive sampling for mesh spectrum editing

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiang-jun; ZHANG Hong-xin; BAO Hu-jun

    2006-01-01

    A mesh editing framework is presented in this paper, which integrates Free-Form Deformation (FFD) and geometry signal processing. By using simplified model from original mesh, the editing task can be accomplished with a few operations. We take the deformation of the proxy and the position coordinates of the mesh models as geometry signal. Wavelet analysis is employed to separate local detail information gracefully. The crucial innovation of this paper is a new adaptive regular sampling approach for our signal analysis based editing framework. In our approach, an original mesh is resampled and then refined iteratively which reflects optimization of our proposed spectrum preserving energy. As an extension of our spectrum editing scheme,the editing principle is applied to geometry details transferring, which brings satisfying results.

  13. Mesh Processing in Medical Image Analysis

    DEFF Research Database (Denmark)

    The following topics are dealt with: mesh processing; medical image analysis; interactive freeform modeling; statistical shape analysis; clinical CT images; statistical surface recovery; automated segmentation; cerebral aneurysms; and real-time particle-based representation....

  14. Obtuse triangle suppression in anisotropic meshes

    KAUST Repository

    Sun, Feng

    2011-12-01

    Anisotropic triangle meshes are used for efficient approximation of surfaces and flow data in finite element analysis, and in these applications it is desirable to have as few obtuse triangles as possible to reduce the discretization error. We present a variational approach to suppressing obtuse triangles in anisotropic meshes. Specifically, we introduce a hexagonal Minkowski metric, which is sensitive to triangle orientation, to give a new formulation of the centroidal Voronoi tessellation (CVT) method. Furthermore, we prove several relevant properties of the CVT method with the newly introduced metric. Experiments show that our algorithm produces anisotropic meshes with much fewer obtuse triangles than using existing methods while maintaining mesh anisotropy. © 2011 Elsevier B.V. All rights reserved.

  15. Removal of line artifacts on mesh boundary in computer generated hologram by mesh phase matching.

    Science.gov (United States)

    Park, Jae-Hyeung; Yeom, Han-Ju; Kim, Hee-Jae; Zhang, HuiJun; Li, BoNi; Ji, Yeong-Min; Kim, Sang-Hoo

    2015-03-23

    Mesh-based computer generated hologram enables realistic and efficient representation of three-dimensional scene. However, the dark line artifacts on the boundary between neighboring meshes are frequently observed, degrading the quality of the reconstruction. In this paper, we propose a simple technique to remove the dark line artifacts by matching the phase on the boundary of neighboring meshes. The feasibility of the proposed method is confirmed by the numerical and optical reconstruction of the generated hologram.

  16. MHD simulations on an unstructured mesh

    Energy Technology Data Exchange (ETDEWEB)

    Strauss, H.R. [New York Univ., NY (United States); Park, W.; Belova, E.; Fu, G.Y. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Longcope, D.W. [Univ. of Montana, Missoula, MT (United States); Sugiyama, L.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-12-31

    Two reasons for using an unstructured computational mesh are adaptivity, and alignment with arbitrarily shaped boundaries. Two codes which use finite element discretization on an unstructured mesh are described. FEM3D solves 2D and 3D RMHD using an adaptive grid. MH3D++, which incorporates methods of FEM3D into the MH3D generalized MHD code, can be used with shaped boundaries, which might be 3D.

  17. Mesh Processing in Medical Image Analysis

    DEFF Research Database (Denmark)

    The following topics are dealt with: mesh processing; medical image analysis; interactive freeform modeling; statistical shape analysis; clinical CT images; statistical surface recovery; automated segmentation; cerebral aneurysms; and real-time particle-based representation.......The following topics are dealt with: mesh processing; medical image analysis; interactive freeform modeling; statistical shape analysis; clinical CT images; statistical surface recovery; automated segmentation; cerebral aneurysms; and real-time particle-based representation....

  18. Vector field processing on triangle meshes

    OpenAIRE

    De Goes, Fernando; Desbrun, Mathieu; Tong, Yiying

    2015-01-01

    While scalar fields on surfaces have been staples of geometry processing, the use of tangent vector fields has steadily grown in geometry processing over the last two decades: they are crucial to encoding directions and sizing on surfaces as commonly required in tasks such as texture synthesis, non-photorealistic rendering, digital grooming, and meshing. There are, however, a variety of discrete representations of tangent vector fields on triangle meshes, and each approach offers different tr...

  19. Unstructured Mesh Movement and Viscous Mesh Generation for CFD-Based Design Optimization Project

    Data.gov (United States)

    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)...

  20. Mesh geometry impact on Micromegas performance with an Exchangeable Mesh prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kuger, F., E-mail: fabian.kuger@cern.ch [CERN, Geneva (Switzerland); Julius-Maximilians-Universität, Würzburg (Germany); Bianco, M.; Iengo, P. [CERN, Geneva (Switzerland); Sekhniaidze, G. [CERN, Geneva (Switzerland); Universita e INFN, Napoli (Italy); Veenhof, R. [Uludağ University, Bursa (Turkey); Wotschack, J. [CERN, Geneva (Switzerland)

    2016-07-11

    The reconstruction precision of gaseous detectors is limited by losses of primary electrons during signal formation. In addition to common gas related losses, like attachment, Micromegas suffer from electron absorption during its transition through the micro mesh. This study aims for a deepened understanding of electron losses and their dependency on the mesh geometry. It combines experimental results obtained with a novel designed Exchangeable Mesh Micromegas (ExMe) and advanced microscopic-tracking simulations (ANSYS and Garfield++) of electron drift and mesh transition.

  1. Robust moving mesh algorithms for hybrid stretched meshes: Application to moving boundaries problems

    Science.gov (United States)

    Landry, Jonathan; Soulaïmani, Azzeddine; Luke, Edward; Ben Haj Ali, Amine

    2016-12-01

    A robust Mesh-Mover Algorithm (MMA) approach is designed to adapt meshes of moving boundaries problems. A new methodology is developed from the best combination of well-known algorithms in order to preserve the quality of initial meshes. In most situations, MMAs distribute mesh deformation while preserving a good mesh quality. However, invalid meshes are generated when the motion is complex and/or involves multiple bodies. After studying a few MMA limitations, we propose the following approach: use the Inverse Distance Weighting (IDW) function to produce the displacement field, then apply the Geometric Element Transformation Method (GETMe) smoothing algorithms to improve the resulting mesh quality, and use an untangler to revert negative elements. The proposed approach has been proven efficient to adapt meshes for various realistic aerodynamic motions: a symmetric wing that has suffered large tip bending and twisting and the high-lift components of a swept wing that has moved to different flight stages. Finally, the fluid flow problem has been solved on meshes that have moved and they have produced results close to experimental ones. However, for situations where moving boundaries are too close to each other, more improvements need to be made or other approaches should be taken, such as an overset grid method.

  2. TVD differencing on three-dimensional unstructured meshes with monotonicity-preserving correction of mesh skewness

    Science.gov (United States)

    Denner, Fabian; van Wachem, Berend G. M.

    2015-10-01

    Total variation diminishing (TVD) schemes are a widely applied group of monotonicity-preserving advection differencing schemes for partial differential equations in numerical heat transfer and computational fluid dynamics. These schemes are typically designed for one-dimensional problems or multidimensional problems on structured equidistant quadrilateral meshes. Practical applications, however, often involve complex geometries that cannot be represented by Cartesian meshes and, therefore, necessitate the application of unstructured meshes, which require a more sophisticated discretisation to account for their additional topological complexity. In principle, TVD schemes are applicable to unstructured meshes, however, not all the data required for TVD differencing is readily available on unstructured meshes, and the solution suffers from considerable numerical diffusion as a result of mesh skewness. In this article we analyse TVD differencing on unstructured three-dimensional meshes, focusing on the non-linearity of TVD differencing and the extrapolation of the virtual upwind node. Furthermore, we propose a novel monotonicity-preserving correction method for TVD schemes that significantly reduces numerical diffusion caused by mesh skewness. The presented numerical experiments demonstrate the importance of accounting for the non-linearity introduced by TVD differencing and of imposing carefully chosen limits on the extrapolated virtual upwind node, as well as the efficacy of the proposed method to correct mesh skewness.

  3. Discrete differential geometry: the nonplanar quadrilateral mesh.

    Science.gov (United States)

    Twining, Carole J; Marsland, Stephen

    2012-06-01

    We consider the problem of constructing a discrete differential geometry defined on nonplanar quadrilateral meshes. Physical models on discrete nonflat spaces are of inherent interest, as well as being used in applications such as computation for electromagnetism, fluid mechanics, and image analysis. However, the majority of analysis has focused on triangulated meshes. We consider two approaches: discretizing the tensor calculus, and a discrete mesh version of differential forms. While these two approaches are equivalent in the continuum, we show that this is not true in the discrete case. Nevertheless, we show that it is possible to construct mesh versions of the Levi-Civita connection (and hence the tensorial covariant derivative and the associated covariant exterior derivative), the torsion, and the curvature. We show how discrete analogs of the usual vector integral theorems are constructed in such a way that the appropriate conservation laws hold exactly on the mesh, rather than only as approximations to the continuum limit. We demonstrate the success of our method by constructing a mesh version of classical electromagnetism and discuss how our formalism could be used to deal with other physical models, such as fluids.

  4. Automatic Scheme Selection for Toolkit Hex Meshing

    Energy Technology Data Exchange (ETDEWEB)

    TAUTGES,TIMOTHY J.; WHITE,DAVID R.

    1999-09-27

    Current hexahedral mesh generation techniques rely on a set of meshing tools, which when combined with geometry decomposition leads to an adequate mesh generation process. Of these tools, sweeping tends to be the workhorse algorithm, accounting for at least 50% of most meshing applications. Constraints which must be met for a volume to be sweepable are derived, and it is proven that these constraints are necessary but not sufficient conditions for sweepability. This paper also describes a new algorithm for detecting extruded or sweepable geometries. This algorithm, based on these constraints, uses topological and local geometric information, and is more robust than feature recognition-based algorithms. A method for computing sweep dependencies in volume assemblies is also given. The auto sweep detect and sweep grouping algorithms have been used to reduce interactive user time required to generate all-hexahedral meshes by filtering out non-sweepable volumes needing further decomposition and by allowing concurrent meshing of independent sweep groups. Parts of the auto sweep detect algorithm have also been used to identify independent sweep paths, for use in volume-based interval assignment.

  5. Hydrodynamic simulations on a moving Voronoi mesh

    CERN Document Server

    Springel, Volker

    2011-01-01

    At the heart of any method for computational fluid dynamics lies the question of how the simulated fluid should be discretized. Traditionally, a fixed Eulerian mesh is often employed for this purpose, which in modern schemes may also be adaptively refined during a calculation. Particle-based methods on the other hand discretize the mass instead of the volume, yielding an approximately Lagrangian approach. It is also possible to achieve Lagrangian behavior in mesh-based methods if the mesh is allowed to move with the flow. However, such approaches have often been fraught with substantial problems related to the development of irregularity in the mesh topology. Here we describe a novel scheme that eliminates these weaknesses. It is based on a moving unstructured mesh defined by the Voronoi tessellation of a set of discrete points. The mesh is used to solve the hyperbolic conservation laws of ideal hydrodynamics with a finite volume approach, based on a second-order Godunov scheme with an exact Riemann solver. A...

  6. Acquiring Plausible Predications from MEDLINE by Clustering MeSH Annotations.

    Science.gov (United States)

    Miñarro-Giménez, Jose Antonio; Kreuzthaler, Markus; Bernhardt-Melischnig, Johannes; Martínez-Costa, Catalina; Schulz, Stefan

    2015-01-01

    The massive accumulation of biomedical knowledge is reflected by the growth of the literature database MEDLINE with over 23 million bibliographic records. All records are manually indexed by MeSH descriptors, many of them refined by MeSH subheadings. We use subheading information to cluster types of MeSH descriptor co-occurrences in MEDLINE by processing co-occurrence information provided by the UMLS. The goal is to infer plausible predicates to each resulting cluster. In an initial experiment this was done by grouping disease-pharmacologic substance co-occurrences into six clusters. Then, a domain expert manually performed the assignment of meaningful predicates to the clusters. The mean accuracy of the best ten generated biomedical facts of each cluster was 85%. This result supports the evidence of the potential of MeSH subheadings for extracting plausible medical predications from MEDLINE.

  7. Types of study in medical research: part 3 of a series on evaluation of scientific publications.

    Science.gov (United States)

    Röhrig, Bernd; du Prel, Jean-Baptist; Wachtlin, Daniel; Blettner, Maria

    2009-04-01

    The choice of study type is an important aspect of the design of medical studies. The study design and consequent study type are major determinants of a study's scientific quality and clinical value. This article describes the structured classification of studies into two types, primary and secondary, as well as a further subclassification of studies of primary type. This is done on the basis of a selective literature search concerning study types in medical research, in addition to the authors' own experience. Three main areas of medical research can be distinguished by study type: basic (experimental), clinical, and epidemiological research. Furthermore, clinical and epidemiological studies can be further subclassified as either interventional or noninterventional. The study type that can best answer the particular research question at hand must be determined not only on a purely scientific basis, but also in view of the available financial resources, staffing, and practical feasibility (organization, medical prerequisites, number of patients, etc.).

  8. Colonization and osteogenic differentiation of different stem cell sources on electrospun nanofiber meshes.

    Science.gov (United States)

    Kolambkar, Yash M; Peister, Alexandra; Ekaputra, Andrew K; Hutmacher, Dietmar W; Guldberg, Robert E

    2010-10-01

    Numerous challenges remain in the successful clinical translation of cell-based therapies for musculoskeletal tissue repair, including the identification of an appropriate cell source and a viable cell delivery system. The aim of this study was to investigate the attachment, colonization, and osteogenic differentiation of two stem cell types, human mesenchymal stem cells (hMSCs) and human amniotic fluid stem (hAFS) cells, on electrospun nanofiber meshes. We demonstrate that nanofiber meshes are able to support these cell functions robustly, with both cell types demonstrating strong osteogenic potential. Differences in the kinetics of osteogenic differentiation were observed between hMSCs and hAFS cells, with the hAFS cells displaying a delayed alkaline phosphatase peak, but elevated mineral deposition, compared to hMSCs. We also compared the cell behavior on nanofiber meshes to that on tissue culture plastic, and observed that there is delayed initial attachment and proliferation on meshes, but enhanced mineralization at a later time point. Finally, cell-seeded nanofiber meshes were found to be effective in colonizing three-dimensional scaffolds in an in vitro system. This study provides support for the use of the nanofiber mesh as a model surface for cell culture in vitro, and a cell delivery vehicle for the repair of bone defects in vivo.

  9. Fire performance of basalt FRP mesh reinforced HPC thin plates

    DEFF Research Database (Denmark)

    Hulin, Thomas; Hodicky, Kamil; Schmidt, Jacob Wittrup;

    2013-01-01

    An experimental program was carried out to investigate the influence of basalt FRP (BFRP) reinforcing mesh on the fire behaviour of thin high performance concrete (HPC) plates applied to sandwich elements. Samples with BFRP mesh were compared to samples with no mesh, samples with steel mesh...

  10. A novel partitioning method for block-structured adaptive meshes

    Science.gov (United States)

    Fu, Lin; Litvinov, Sergej; Hu, Xiangyu Y.; Adams, Nikolaus A.

    2017-07-01

    We propose a novel partitioning method for block-structured adaptive meshes utilizing the meshless Lagrangian particle concept. With the observation that an optimum partitioning has high analogy to the relaxation of a multi-phase fluid to steady state, physically motivated model equations are developed to characterize the background mesh topology and are solved by multi-phase smoothed-particle hydrodynamics. In contrast to well established partitioning approaches, all optimization objectives are implicitly incorporated and achieved during the particle relaxation to stationary state. Distinct partitioning sub-domains are represented by colored particles and separated by a sharp interface with a surface tension model. In order to obtain the particle relaxation, special viscous and skin friction models, coupled with a tailored time integration algorithm are proposed. Numerical experiments show that the present method has several important properties: generation of approximately equal-sized partitions without dependence on the mesh-element type, optimized interface communication between distinct partitioning sub-domains, continuous domain decomposition which is physically localized and implicitly incremental. Therefore it is particularly suitable for load-balancing of high-performance CFD simulations.

  11. Euclidean Distance Distortion Based Robust and Blind Mesh Watermarking

    Directory of Open Access Journals (Sweden)

    Yesmine Ben Amar

    2016-12-01

    Full Text Available The three-dimensional (3D polygonal meshes are recently widely used in several domains, which necessitate the realistic visualization of the objects. Moreover, there is an urgent need to protect the 3D data properties for preventing unauthorized reproduction. The 3D digital watermarking technology is one of the best solutions to protect data from piracy during transmission through the internet. The current work proposed a novel robust watermarking scheme of polygonal meshes for copyright protection purposes. The proposed algorithm is based on the characteristics of the mesh geometry to embed a sequence of data bits into the object by slightly adjusting the vertex positions. Furthermore, the proposed method used a blind detection scheme. The watermarked model is perceptually indistinguishable from the original one and the embedded watermark is invariant to affine transformation. Through simulations, the quality of the watermarked object as well as the inserted watermark robustness against various types of attacks were tested and evaluated to prove the validity and the efficiency of our algorithm.

  12. A novel partitioning method for block-structured adaptive meshes

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Lin, E-mail: lin.fu@tum.de; Litvinov, Sergej, E-mail: sergej.litvinov@aer.mw.tum.de; Hu, Xiangyu Y., E-mail: xiangyu.hu@tum.de; Adams, Nikolaus A., E-mail: nikolaus.adams@tum.de

    2017-07-15

    We propose a novel partitioning method for block-structured adaptive meshes utilizing the meshless Lagrangian particle concept. With the observation that an optimum partitioning has high analogy to the relaxation of a multi-phase fluid to steady state, physically motivated model equations are developed to characterize the background mesh topology and are solved by multi-phase smoothed-particle hydrodynamics. In contrast to well established partitioning approaches, all optimization objectives are implicitly incorporated and achieved during the particle relaxation to stationary state. Distinct partitioning sub-domains are represented by colored particles and separated by a sharp interface with a surface tension model. In order to obtain the particle relaxation, special viscous and skin friction models, coupled with a tailored time integration algorithm are proposed. Numerical experiments show that the present method has several important properties: generation of approximately equal-sized partitions without dependence on the mesh-element type, optimized interface communication between distinct partitioning sub-domains, continuous domain decomposition which is physically localized and implicitly incremental. Therefore it is particularly suitable for load-balancing of high-performance CFD simulations.

  13. MESH2D GRID GENERATOR DESIGN AND USE

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Mesh-based phase contrast Fourier transform imaging

    Science.gov (United States)

    Tahir, Sajjad; Bashir, Sajid; MacDonald, C. A.; Petruccelli, Jonathan C.

    2017-04-01

    Traditional x-ray radiography is limited by low attenuation contrast in materials of low electron density. Phase contrast imaging offers the potential to improve the contrast between such materials, but due to the requirements on the spatial coherence of the x-ray beam, practical implementation of such systems with tabletop (i.e. non-synchrotron) sources has been limited. One phase imaging technique employs multiple fine-pitched gratings. However, the strict manufacturing tolerances and precise alignment requirements have limited the widespread adoption of grating-based techniques. In this work, we have investigated a recently developed technique that utilizes a single grid of much coarser pitch. Our system consisted of a low power 100 μm spot Mo source, a CCD with 22 μm pixel pitch, and either a focused mammography linear grid or a stainless steel woven mesh. Phase is extracted from a single image by windowing and comparing data localized about harmonics of the mesh in the Fourier domain. The effects on the diffraction phase contrast and scattering amplitude images of varying grid types and periods, and of varying the width of the window function used to separate the harmonics were investigated. Using the wire mesh, derivatives of the phase along two orthogonal directions were obtained and combined to form improved phase contrast images.

  15. Allocation of Public Resources for Psychological Therapy between Types of Mental Health Condition: Towards Structural Balance

    Science.gov (United States)

    Tustin, Don

    2009-01-01

    This paper addresses issues of allocating public resources efficiently between mental health conditions that are associated with different levels of disability, and presents an adaptation of an established framework to help decision-making in this area. The adapted framework refers to psychological interventions that are universal, indicated,…

  16. Study for the Forming Principle of Logix Gear Tooth Profile and Its Mesh Performance

    Institute of Scientific and Technical Information of China (English)

    Lee; Leckseng; Linda; Lee

    2002-01-01

    In recent years, a new type of gear named Logix gea r was developed. Actually, the tooth profile of this new type of gear is composed of lots of micro-segment involute curves, and on the profile, there exist lots of points, which their relative curvatures are equal to zero. This can result in the sliding coefficient smaller between two meshed Logix gears, and the mesh ch aracteristic becomes almost rolling transmission from sliding transmission accor dingly. So, this new type of gear has lots of advanta...

  17. Cross sectional: perception of children from public and private schools regarding the esthetic impact of different types of face masks.

    Science.gov (United States)

    Pithon, Matheus Melo; Ferraz, Caio Sousa; de Oliveira, Gabriel Couto; Dos Santos, Adrielle Mangabeira; Couto, Felipe Santos; da Silva Coqueiro, Raildo; Dos Santos, Rogério Lacerda

    2013-01-01

    The purpose was to evaluate the esthetic perception among children from public and private schools regarding the use of different types of face masks. Six different types of orthopedic face masks made from images of the same patient were evaluated. Initially, the images were standardized with the help of Adobe Photoshop software. The variable considered was type of mask: (A) Delaire with facebow; (B) Petit; (C) Delaire; (D)Turley; (E) Hickham; and (F) Sky Hook. The images were printed on photographic paper and incorporated into a specific personalized questionnaire that was distributed to 7- to 10-year-olds attending public and private schools (n=120). The data obtained were compared via chi-square, Fisher's exact tests, Mann-Whitney and Spearman's tests. The proportion of participants who chose image A as the best was significantly higher (P.05). The mean scores between groups were not significantly correlated between private vs public schoolchildren (r=0.32) and between boys and girls (r=0.41). Delaire face mask with facebow was chosen as the most attractive, and the Petit and Sky Hook face masks were voted the least attractive.

  18. Comparison of the effects of two bongo net mesh sizes on the estimation of abundance and size of Engraulidae eggs

    Directory of Open Access Journals (Sweden)

    Jana Menegassi del Favero

    2015-06-01

    Full Text Available Abstract Studies of ichthyoplankton retention by nets of different mesh sizes are important because they help in choosing a sampler when planning collection and the establishment of correction factors. These factors make it possible to compare studies performed with nets of different mesh sizes. In most studies of mesh retention of fish eggs, the taxonomic identification is done at the family level, resulting in the loss of detailed information. We separated Engraulidae eggs, obtained with 0.333 mm and 0.505 mm mesh bongo nets at 172 oceanographic stations in the southeastern Brazilian Bight, into four groups based on their morphometric characteristics. The difference in the abundance of eggs caught by the two nets was not significant for those groups with highest volume, types A and B, but in type C (Engraulis anchoita, the most eccentric, and in type D, of the smallest volume, the difference was significant. However, no significant difference was observed in the egg size sampled with each net for E. anchoita and type D, which exhibited higher abundance in the 0.333 mm mesh net and minor axis varying from 0.45-0.71 mm, smaller than the 0.505 mm mesh aperture and the mesh diagonal.

  19. Polyglactine/Polypropylene Mesh vs. Propylene Mesh: Is there a need for newer prosthesis in inguinal hernia?

    Directory of Open Access Journals (Sweden)

    Khan Nadim

    2010-01-01

    Full Text Available Background/Aim: To compare outcomes of light and heavy weight mesh for repair of inguinal hernia. Materials and Methods: This study was conducted at the Department of Surgery; Lady Reading Hospital, Peshawar from January 1, 2007 to December 31, 2008. Patients were divided into two groups based on the type of mesh implanted for inguinal hernia repair. Group 1 included patients in whom light weight composite (VyproII; mesh is implanted: Group 2 included patients in whom polypropylene (Prolene R mesh is implanted. Data concerning the complications and post operative pain in the perioperative and postoperative period were collected and analyzed. Categorical data were presented as percentages with 95% confidence intervals and compared using a χ2 test and P < 0.05 were considered significant. Results: Following allocation and exclusion of violating cases, 111 patients in group 1 and 138 patients in group 2 were analyzed. The mean age in group 1 was 38.20 ± 13.34 years and in group 2 was 39.55 ± 13.70 (P = 0.434. In group 1, hematoma formation was observed in four cases (3.6%, while it was observed in six cases (4.2% in group 2 (P = 0.766. During the entire study, ten patients in all developed urinary retention, three of which required transient catheterization. One year post operation, there was a recurrence in only five cases overall, while only two patients complained of pain (P = 0.826. Conclusion: The frequency of postoperative pain and complications in patients was similar in both groups.

  20. Multiple Staggered Mesh Ewald: Boosting the Accuracy of the Smooth Particle Mesh Ewald Method

    CERN Document Server

    Wang, Han; Fang, Jun

    2016-01-01

    The smooth particle mesh Ewald (SPME) method is the standard method for computing the electrostatic interactions in the molecular simulations. In this work, the multiple staggered mesh Ewald (MSME) method is proposed to boost the accuracy of the SPME method. Unlike the SPME that achieves higher accuracy by refining the mesh, the MSME improves the accuracy by averaging the standard SPME forces computed on, e.g. $M$, staggered meshes. We prove, from theoretical perspective, that the MSME is as accurate as the SPME, but uses $M^2$ times less mesh points in a certain parameter range. In the complementary parameter range, the MSME is as accurate as the SPME with twice of the interpolation order. The theoretical conclusions are numerically validated both by a uniform and uncorrelated charge system, and by a three-point-charge water system that is widely used as solvent for the bio-macromolecules.

  1. Conservative interpolation between general spherical meshes

    Directory of Open Access Journals (Sweden)

    E. Kritsikis

    2015-06-01

    Full Text Available An efficient, local, explicit, second-order, conservative interpolation algorithm between spherical meshes is presented. The cells composing the source and target meshes may be either spherical polygons or longitude–latitude quadrilaterals. Second-order accuracy is obtained by piecewise-linear finite volume reconstruction over the source mesh. Global conservation is achieved through the introduction of a supermesh, whose cells are all possible intersections of source and target cells. Areas and intersections are computed exactly to yield a geometrically exact method. The main efficiency bottleneck caused by the construction of the supermesh is overcome by adopting tree-based data structures and algorithms, from which the mesh connectivity can also be deduced efficiently. The theoretical second-order accuracy is verified using a smooth test function and pairs of meshes commonly used for atmospheric modelling. Experiments confirm that the most expensive operations, especially the supermesh construction, have O(NlogN computational cost. The method presented is meant to be incorporated in pre- or post-processing atmospheric modelling pipelines, or directly into models for flexible input/output. It could also serve as a basis for conservative coupling between model components, e.g. atmosphere and ocean.

  2. Conservative interpolation between general spherical meshes

    Science.gov (United States)

    Kritsikis, Evaggelos; Aechtner, Matthias; Meurdesoif, Yann; Dubos, Thomas

    2017-01-01

    An efficient, local, explicit, second-order, conservative interpolation algorithm between spherical meshes is presented. The cells composing the source and target meshes may be either spherical polygons or latitude-longitude quadrilaterals. Second-order accuracy is obtained by piece-wise linear finite-volume reconstruction over the source mesh. Global conservation is achieved through the introduction of a supermesh, whose cells are all possible intersections of source and target cells. Areas and intersections are computed exactly to yield a geometrically exact method. The main efficiency bottleneck caused by the construction of the supermesh is overcome by adopting tree-based data structures and algorithms, from which the mesh connectivity can also be deduced efficiently.The theoretical second-order accuracy is verified using a smooth test function and pairs of meshes commonly used for atmospheric modelling. Experiments confirm that the most expensive operations, especially the supermesh construction, have O(NlogN) computational cost. The method presented is meant to be incorporated in pre- or post-processing atmospheric modelling pipelines, or directly into models for flexible input/output. It could also serve as a basis for conservative coupling between model components, e.g., atmosphere and ocean.

  3. Resolution of the Gross-Pitaevskii equation with the imaginary-time method on a Lagrange mesh.

    Science.gov (United States)

    Baye, D; Sparenberg, J-M

    2010-11-01

    The Lagrange-mesh method is an approximate variational calculation which has the simplicity of a mesh calculation. Combined with the imaginary-time method, it is applied to the iterative resolution of the Gross-Pitaevskii equation. Two variants of a fourth-order factorization of the exponential of the Hamiltonian and two types of mesh (Lagrange-Hermite and Lagrange-sinc) are employed and compared. The accuracy is checked with the help of these comparisons and of the virial theorem. The Lagrange-Hermite mesh provides very accurate results with short computing times for values of the dimensionless parameter of the nonlinear term up to 10⁴. For higher values up to 10⁷, the Lagrange-sinc mesh is more efficient. Examples are given for anisotropic and nonseparable trapping potentials.

  4. Laparoscopic-assisted Ventral Hernia Repair: Primary Fascial Repair with Polyester Mesh versus Polyester Mesh Alone.

    Science.gov (United States)

    Karipineni, Farah; Joshi, Priya; Parsikia, Afshin; Dhir, Teena; Joshi, Amit R T

    2016-03-01

    Laparoscopic-assisted ventral hernia repair (LAVHR) with mesh is well established as the preferred technique for hernia repair. We sought to determine whether primary fascial closure and/or overlap of the mesh reduced recurrence and/or complications. We conducted a retrospective review on 57 LAVHR patients using polyester composite mesh between August 2010 and July 2013. They were divided into mesh-only (nonclosure) and primary fascial closure with mesh (closure) groups. Patient demographics, prior surgical history, mesh overlap, complications, and recurrence rates were compared. Thirty-nine (68%) of 57 patients were in the closure group and 18 (32%) in the nonclosure group. Mean defect sizes were 15.5 and 22.5 cm(2), respectively. Participants were followed for a mean of 1.3 years [standard deviation (SD) = 0.7]. Recurrence rates were 2/39 (5.1%) in the closure group and 1/18 (5.6%) in the nonclosure group (P = 0.947). There were no major postoperative complications in the nonclosure group. The closure group experienced four (10.3%) complications. This was not a statistically significant difference (P = 0.159). The median mesh-to-hernia ratio for all repairs was 15.2 (surface area) and 3.9 (diameter). Median length of stay was 14.5 hours (1.7-99.3) for patients with nonclosure and 11.9 hours (6.9-90.3 hours) for patients with closure (P = 0.625). In conclusion, this is one of the largest series of LAVHR exclusively using polyester dual-sided mesh. Our recurrence rate was about 5 per cent. Significant mesh overlap is needed to achieve such low recurrence rates. Primary closure of hernias seems less important than adequate mesh overlap in preventing recurrence after LAVHR.

  5. Flip-Chip GaN-Based Light-Emitting Diodes with Mesh-Contact Electrodes

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan-Xu; XU Chen; HAN Jun; SHEN Guang-Di

    2007-01-01

    @@ GaN-based light-emitting diodes (LEDs) with mesh-contact electrodes have been developed. The p-type ohmic contact layer is composed of oxidized Ni/Au mesh and NiO overlay (20 (A)). An Ag (3000 (A)) omni-directional reflector covers the p-type contact. The n-type contact is a Ti/Al planar film with a 10-μm-width Ti/Al stripe.The Ti/Al stripe surrounds the centre of LED mesa. With a 20-mA current injection, the light output power of GaN-based LEDs with mesh-contact electrodes is 23% higher than that of the conventional LEDs.

  6. Performance of Implementation IBR-DTN and Batman-Adv Routing Protocol in Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Herman Yuliandoko

    2016-03-01

    Full Text Available Wireless mesh networks is a network which has high mobility and flexibility network. In Wireless mesh networks nodes are free to move and able to automatically build a network connection with other nodes. High mobility, heterogeneous condition and intermittent network connectivity cause data packets drop during wireless communication and it becomes a problem in the wireless mesh networks. This condition can happen because wireless mesh networks use connectionless networking type such as IP protocol which it is not tolerant to delay. To solve this condition it is needed a technology to keep data packets when the network is disconnect. Delay tolerant technology is a technology that provides store and forward mechanism and it can prevent packet data dropping during communication. In our research, we proposed a test bed wireless mesh networks implementation by using proactive routing protocol and combining with delay tolerant technology. We used Batman-adv routing protocol and IBR-DTN on our research. We measured some particular performance aspect of networking such as packet loss, delay, and throughput of the network. We identified that delay tolerant could keep packet data from dropping better than current wireless mesh networks in the intermittent network condition. We also proved that IBR-DTN and Batman-adv could run together on the wireless mesh networks. In The experiment throughput test result of IBR-DTN was higher than Current TCP on the LoS (Line of Side and on environment with obstacle. Keywords: Delay Tolerant, IBR-DTN, Wireless Mesh, Batman-adv, Performance

  7. Biomechanical and morphological study of a new elastic mesh (Ciberlastic) to repair abdominal wall defects.

    Science.gov (United States)

    Calvo, B; Pascual, G; Peña, E; Pérez-Khöler, B; Rodríguez, M; Bellón, J M

    2016-06-01

    The aim of this study was to conduct a preclinical evaluation of the behaviour of a new type of abdominal LW prosthesis (Ciberlastic), which was designed with a non-absorbable elastic polyurethane monofilament (Assuplus, Assut Europe, Italy) to allow greater adaptability to mechanical area requirements and higher bio-mimicking with the newly formed surrounding tissues. Our hypothesis was that an increase in the elasticity of the mesh filament could improve the benefits of LW prostheses. To verify our hypothesis, we compared the short- and long-term behaviour of Ciberlastic and Optilene(®) elastic commercial meshes by repairing the partially herniated abdomen in New Zealand White rabbits. The implanted meshes were mechanically and histologically assessed at 14 and 180 days post-implant. We mechanically characterized the partially herniated repaired muscle tissue and also determined mesh shrinkage at different post-implant times. This was followed by a histological study in which the tissue incorporation process was analysed over time. The new prosthesis designed by our group achieved good behaviour that was similar to that of Optilene(®), one of the most popular LW prostheses on the market, with the added advantage of its elastic property. The mechanical properties are significantly lower than those of the polypropylene Optilene(®) mesh, and the new elastic mesh meets the basic mechanical requirements for positioning in the abdominal wall, which was also demonstrated by the absence of recurrences after implantation in the experimental model. We found that the growth of a connective tissue rich in collagen over the hernial defect and the proper deposit of the collagen fibres in the regenerated tissue substantially modified the original properties of the mesh, thereby increasing its biomechanical strength and making the whole tissue/mesh stiffer.

  8. Development of oral and extra-oral endosseous craniofacial implants by using a mesh structure for connective tissue attachment.

    Science.gov (United States)

    Mita, Atsushi; Yagihara, Atsushi; Wang, Wei; Takakuda, Kazuo

    2014-03-19

    Connective tissue attachment to a mesh structure incorporated on the surface of oral implants and extra-oral endosseous craniofacial implants (EOECI) was investigated. Two types of implants were prepared: TI and TI-Mesh. TI was composed of an upper and a lower component, both comprised of a titanium cylinder, which could be connected using a titanium screw. The composition of the TIMesh was similar, but the lower cylinder had a lateral groove that was covered with a titanium mesh. In animal experiments performed using rat calvaria, the lower component was first implanted and was left submerged for 3 weeks, then the upper component was mounted percutaneously. After an additional 2 weeks, each implant and the surrounding tissues were harvested and evaluated. Histological observations revealed collagen fibers originating from surrounding hypodermal tissues anchored to the mesh structures of the TI-Mesh whereas no such collagen fibers were observed around TI. Significantly greater values of the attachment strength, the thickness of the dermal tissue, the thickness of hypodermal tissue, and the attachment lengths were observed in TI-Mesh than those of TI. Thus connective tissue attachment with collagen fibers anchored to the mesh was achieved by incorporating mesh structures into the percutaneously placed implants.

  9. Polypropylene-based composite mesh versus standard polypropylene mesh in the reconstruction of complicated large abdominal wall hernias: a prospective randomized study.

    Science.gov (United States)

    Kassem, M I; El-Haddad, H M

    2016-10-01

    To compare polypropylene mesh positioned onlay supported by omentum and/or peritoneum versus inlay implantation of polypropylene-based composite mesh in patients with complicated wide-defect ventral hernias. This was a prospective randomized study carried out on 60 patients presenting with complicated large ventral hernia in the period from January 2012 to January 2016 in the department of Gastrointestinal Surgery unit and Surgical Emergency of the Main Alexandria University Hospital, Egypt. Large hernia had an abdominal wall defect that could not be closed. Patients were divided into two groups of 30 patients according to the type of mesh used to deal with the large abdominal wall defect. The study included 38 women (63.3 %) and 22 men (37.7 %); their mean age was 46.5 years (range, 25-70). Complicated incisional hernia was the commonest presentation (56.7 %).The operative and mesh fixation times were longer in the polypropylene group. Seven wound infections and two recurrences were encountered in the propylene group. Mean follow-up was 28.7 months (2-48 months). Composite mesh provided, in one session, satisfactory results in patients with complicated large ventral hernia. The procedure is safe and effective in lowering operative time with a trend of low wound complication and recurrence rates.

  10. Public Preferences Across Europe for Different Forest Stand Types as Sites for Recreation

    Directory of Open Access Journals (Sweden)

    David M. Edwards

    2012-03-01

    Full Text Available A Delphi survey involving experts in forest preference research was carried out to derive scores for the recreational value of 240 forest stand types across Europe. The survey was organized around four regional panels: Great Britain, Nordic Region, Central Europe, and Iberia. In each region, 60 forest stand types were defined according to five forest management alternatives (FMAs on a continuum of management intensity, four phases of development (establishment, young, medium, and adult, and three tree species types (conifer, broadleaved, and mixed stands of conifer and broadleaved. The resulting scores were examined using conjoint analysis to determine the relative importance of the three structural attributes (FMA, phase of development, and tree species type, and each level or component of the attributes. The findings quantify the extent to which forest visitors prefer a degree of management to unmanaged forest nature reserves across the four regions. Phase of development was shown to make the highest contribution to the recreational value of forests while the contribution of tree species type was shown to be relatively unimportant. While the results are indicative, they provide evidence to support long-term retention and low-impact silviculture in forests where recreation is a primary objective of management.

  11. GRChombo: Numerical relativity with adaptive mesh refinement

    Science.gov (United States)

    Clough, Katy; Figueras, Pau; Finkel, Hal; Kunesch, Markus; Lim, Eugene A.; Tunyasuvunakool, Saran

    2015-12-01

    In this work, we introduce {\\mathtt{GRChombo}}: a new numerical relativity code which incorporates full adaptive mesh refinement (AMR) using block structured Berger-Rigoutsos grid generation. The code supports non-trivial ‘many-boxes-in-many-boxes’ mesh hierarchies and massive parallelism through the message passing interface. {\\mathtt{GRChombo}} evolves the Einstein equation using the standard BSSN formalism, with an option to turn on CCZ4 constraint damping if required. The AMR capability permits the study of a range of new physics which has previously been computationally infeasible in a full 3 + 1 setting, while also significantly simplifying the process of setting up the mesh for these problems. We show that {\\mathtt{GRChombo}} can stably and accurately evolve standard spacetimes such as binary black hole mergers and scalar collapses into black holes, demonstrate the performance characteristics of our code, and discuss various physics problems which stand to benefit from the AMR technique.

  12. Retrofitting Masonry Walls with Carbon Mesh

    Directory of Open Access Journals (Sweden)

    Patrick Bischof

    2014-01-01

    Full Text Available Static-cyclic shear load tests and tensile tests on retrofitted masonry walls were conducted at UAS Fribourg for an evaluation of the newly developed retrofitting system, the S&P ARMO-System. This retrofitting system consists of a composite of carbon mesh embedded in a specially adapted high quality spray mortar. It can be applied with established construction techniques using traditional construction materials. The experimental study has shown that masonry walls reinforced by this retrofitting system reach a similar strength and a higher ductility than retrofits by means of bonded carbon fiber reinforced polymer sheets. Hence, the retrofitting system using carbon fiber meshes embedded in a high quality mortar constitutes a good option for static or seismic retrofits or reinforcements for masonry walls. However, the experimental studies also revealed that the mechanical anchorage of carbon mesh may be delicate depending on its design.

  13. NASA Lewis Meshed VSAT Workshop meeting summary

    Science.gov (United States)

    Ivancic, William

    1993-11-01

    NASA Lewis Research Center's Space Electronics Division (SED) hosted a workshop to address specific topics related to future meshed very small-aperture terminal (VSAT) satellite communications networks. The ideas generated by this workshop will help to identify potential markets and focus technology development within the commercial satellite communications industry and NASA. The workshop resulted in recommendations concerning these principal points of interest: the window of opportunity for a meshed VSAT system; system availability; ground terminal antenna sizes; recommended multifrequency for time division multiple access (TDMA) uplink; a packet switch design concept for narrowband; and fault tolerance design concepts. This report presents a summary of group presentations and discussion associated with the technological, economic, and operational issues of meshed VSAT architectures that utilize processing satellites.

  14. Mesh saliency with adaptive local patches

    Science.gov (United States)

    Nouri, Anass; Charrier, Christophe; Lézoray, Olivier

    2015-03-01

    3D object shapes (represented by meshes) include both areas that attract the visual attention of human observers and others less or not attractive at all. This visual attention depends on the degree of saliency exposed by these areas. In this paper, we propose a technique for detecting salient regions in meshes. To do so, we define a local surface descriptor based on local patches of adaptive size and filled with a local height field. The saliency of mesh vertices is then defined as its degree measure with edges weights computed from adaptive patch similarities. Our approach is compared to the state-of-the-art and presents competitive results. A study evaluating the influence of the parameters establishing this approach is also carried out. The strength and the stability of our approach with respect to noise and simplification are also studied.

  15. Performance of a streaming mesh refinement algorithm.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, David C.; Pebay, Philippe Pierre

    2004-08-01

    In SAND report 2004-1617, we outline a method for edge-based tetrahedral subdivision that does not rely on saving state or communication to produce compatible tetrahedralizations. This report analyzes the performance of the technique by characterizing (a) mesh quality, (b) execution time, and (c) traits of the algorithm that could affect quality or execution time differently for different meshes. It also details the method used to debug the several hundred subdivision templates that the algorithm relies upon. Mesh quality is on par with other similar refinement schemes and throughput on modern hardware can exceed 600,000 output tetrahedra per second. But if you want to understand the traits of the algorithm, you have to read the report!

  16. A unified multigrid solver for the Navier-Stokes equations on mixed element meshes

    Science.gov (United States)

    Mavriplis, D. J.; Venkatakrishnan, V.

    1995-01-01

    A unified multigrid solution technique is presented for solving the Euler and Reynolds-averaged Navier-Stokes equations on unstructured meshes using mixed elements consisting of triangles and quadrilaterals in two dimensions, and of hexahedra, pyramids, prisms, and tetrahedra in three dimensions. While the use of mixed elements is by no means a novel idea, the contribution of the paper lies in the formulation of a complete solution technique which can handle structured grids, block structured grids, and unstructured grids of tetrahedra or mixed elements without any modification. This is achieved by discretizing the full Navier-Stokes equations on tetrahedral elements, and the thin layer version of these equations on other types of elements, while using a single edge-based data-structure to construct the discretization over all element types. An agglomeration multigrid algorithm, which naturally handles meshes of any types of elements, is employed to accelerate convergence. An automatic algorithm which reduces the complexity of a given triangular or tetrahedral mesh by merging candidate triangular or tetrahedral elements into quadrilateral or prismatic elements is also described. The gains in computational efficiency afforded by the use of non-simplicial meshes over fully tetrahedral meshes are demonstrated through several examples.

  17. Public attitudes about different types of anti-bullying laws: results from a national survey.

    Science.gov (United States)

    Puhl, Rebecca M; Luedicke, Joerg; King, Kelly M

    2015-02-01

    State anti-bullying laws have been enacted across the United States to address bullying both by and of youths. Although these statutes can provide critical protection to youth, there is debate about whether such laws should enumerate protected classes of youth. Weight-based bullying is an increasingly prevalent form of harassment and it has been overlooked in policy initiatives. Enumeration in existing laws might help protect overweight victims. As no research has examined this issue, we conducted a national survey of American adults (N=1155) to assess public opinion about enactment of anti-bullying laws that vary according to whether or not they enumerate distinguishing characteristics. Our results demonstrated substantial public agreement (ranging from 2/3 to 3/4 of participants) with enactment of state and federal anti-bullying laws that enumerate distinguishing characteristics, including physical appearance and weight, which are currently absent in most statutes. Our evidence can inform policy and legal approaches to protect youth effectively from bullying.

  18. Open preperitoneal groin hernia repair with mesh

    DEFF Research Database (Denmark)

    Andresen, Kristoffer; Rosenberg, Jacob

    2017-01-01

    A systematic review was conducted and reported according to the PRISMA statement. PubMed, Cochrane library and Embase were searched systematically. Studies were included if they provided clinical data with more than 30 days follow up following repair of an inguinal hernia with an open preperitoneal mesh......Background For the repair of inguinal hernias, several surgical methods have been presented where the purpose is to place a mesh in the preperitoneal plane through an open access. The aim of this systematic review was to describe preperitoneal repairs with emphasis on the technique. Data sources...

  19. Adaptive mesh refinement for storm surge

    KAUST Repository

    Mandli, Kyle T.

    2014-03-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the GeoClaw framework and compared to ADCIRC for Hurricane Ike along with observed tide gauge data and the computational cost of each model run. © 2014 Elsevier Ltd.

  20. Relativistic MHD with Adaptive Mesh Refinement

    CERN Document Server

    Anderson, M; Liebling, S L; Neilsen, D; Anderson, Matthew; Hirschmann, Eric; Liebling, Steven L.; Neilsen, David

    2006-01-01

    We solve the relativistic magnetohydrodynamics (MHD) equations using a finite difference Convex ENO method (CENO) in 3+1 dimensions within a distributed parallel adaptive mesh refinement (AMR) infrastructure. In flat space we examine a Balsara blast wave problem along with a spherical blast wave and a relativistic rotor test both with unigrid and AMR simulations. The AMR simulations substantially improve performance while reproducing the resolution equivalent unigrid simulation results. We also investigate the impact of hyperbolic divergence cleaning for the spherical blast wave and relativistic rotor. We include unigrid and mesh refinement parallel performance measurements for the spherical blast wave.

  1. Laparoscopic rectocele repair using polyglactin mesh.

    Science.gov (United States)

    Lyons, T L; Winer, W K

    1997-05-01

    We assessed the efficacy of laparoscopic treatment of rectocele defect using a polyglactin mesh graft. From May 1, 1995, through September 30, 1995, we prospectively evaluated 20 women (age 38-74 yrs) undergoing pelvic floor reconstruction for symptomatic pelvic floor prolapse, with or without hysterectomy. Morbidity of the procedure was extremely low compared with standard transvaginal and transrectal approaches. Patients were followed at 3-month intervals for 1 year. Sixteen had resolution of symptoms. Laparoscopic application of polyglactin mesh for the repair of the rectocele defect is a viable option, although long-term follow-up is necessary.

  2. Adaptive Mesh Refinement for Storm Surge

    CERN Document Server

    Mandli, Kyle T

    2014-01-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the \\geoclaw framework and compared to \\adcirc for Hurricane Ike along with observed tide gauge data and the computational cost of each model run.

  3. CO2 Emissions and Cost by Floor Types of Public Apartment Houses in South Korea

    Directory of Open Access Journals (Sweden)

    Hyoung Jae Jang

    2016-05-01

    Full Text Available In each country in the world, there is a strong need for all industries to reduce CO2 emissions for sustainable development as a preparation for climatic change. The biggest issue in many developed countries, including the United States, is to reduce CO2 emissions for the upcoming implementation of Carbon Emissions Trading. The construction industry, in particular, which accounts for up about 30% of CO2 emissions, will need studies on the amount of CO2 emissions. The purpose of this study is to present the most environmentally friendly and economical apartment house plan types according to the increasing number of layers by evaluating the amount of CO2 emissions and economic efficiency. The results indicated that flat and Y-shaped types are more eco-friendly and economical in lower levels of less than 20 stories. However, the L-shaped type is more highly eco-friendly and economically efficient in higher levels of more than 20 stories. The results of this paper would help to make a decision on the building types and the number of stories in the early stages of construction.

  4. Atlas-Based Automatic Generation of Subject-Specific Finite Element Tongue Meshes.

    Science.gov (United States)

    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.

  5. Involving the public in general practice in an urban district: levels and type of activity and perceptions of obstacles.

    Science.gov (United States)

    Brown, Ian

    2000-07-01

    This paper reports on a study of the level and type of activity used to involve the public in general practice in a city district in the north of England. The association of these activities with features of the general practice organisation and environment were studied. Service providers' perceptions of obstacles were also studied. Data were collected in a survey of all general practice organisations in the district using a postal questionnaire completed by a practice manager. Interviews were conducted with health service managers responsible for primary care development in the district. The study showed that the district had a good track record for innovation in primary care development and in giving emphasis to developing public involvement. However, it also showed that it was difficult to translate policy rhetoric into practical initiatives at the general practice level without evidence of models of best practice, and with limited resources. The survey had a high response of over 84%. It showed that levels of activity were low across the district and only a small minority of general practice teams had undertaken a range of activities to involve the public. The socio-economic environment did not appear to be a factor, but small practices (one or two partners and/or practice population under 3000) were much less likely to develop activities. Pressures of existing workload, lack of resources and public apathy were given as among the main obstacles by survey respondents. The study indicates the challenges faced by Primary Care Groups in developing strands of public involvement. Primary care teams need a clear strategic framework, models of best practice, and adequate resources to manage, change and develop initiatives.

  6. Comparative analysis of morbidity rate in adolescents studied in different types of public educational institutions

    Directory of Open Access Journals (Sweden)

    Nizom Ermatov

    2011-03-01

    Full Text Available Common morbidity rate of adolescents aged from 15 to 18 years has been simultaneously estimated based on their appeals data to the polyclinics. These adolescents studied in public elementary schools and lyceums at medical high educational institutions of Tashkent city. Incidence was in 1.2-1.8 times higher among lyceum students than schoolchildren, while the structure of diseases was similar. The more important factors of morbidity in elementary schools and lyceums include iodine-deficiency, nonspecific respiratory diseases, iron-deficient anemia, gastritis, skin and subcutaneous tissue illnesses. These disease characteristics of in elementary schools and lyceums should be considered when organizing recreational activities, in particular, during improving physical education and optimization of learning environment.

  7. Building WDM wide area resilient transport network from 4-node semi-mesh and mesh sub-networks

    DEFF Research Database (Denmark)

    Limal, Emmanuel; Mikkelsen, Benny; Stubkjær, Kristian

    1997-01-01

    This paper deals with optical transport network design using wavelength division multiplexing (WDM) facilities. It proposes a method for building networks from sub-network combinations. Two types of 4-node sub-networks and their properties are presented. For each sub-network, any fiber break can...... be recovered using re-routing paths. A European network set-up illustrates the method capabilities. The network has 19 nodes connected through 39 links distributed within 9 semi-mesh sub-networks. Comparison is made between local and non-local re-routing and between channel capacities of 2.5 and 10 Gb...

  8. MeshEZW: an image coder using mesh and finite elements

    Science.gov (United States)

    Landais, Thomas; Bonnaud, Laurent; Chassery, Jean-Marc

    2003-08-01

    In this paper, we present a new method to compress the information in an image, called MeshEZW. The proposed approach is based on the finite elements method, a mesh construction and a zerotree method. The zerotree method is an adaptive of the EZW algorithm with two new symbols for increasing the performance. These steps allow a progressive representation of the image by the automatic construction of a bitstream. The mesh structure is adapted to the image compression domain and is defined to allow video comrpession. The coder is described and some preliminary results are discussed.

  9. Scientometric study of academic publications on antioxidative herbal medicines in type 2 diabetes mellitus

    OpenAIRE

    Tabatabaei-Malazy, Ozra; Ramezani, Amir; Atlasi, Rasha; Larijani, Bagher; Abdollahi, Mohammad

    2016-01-01

    Background Scientometric analysis is increasingly used for research assessment. We aimed to perform a scientometric analysis of research productivity in field of antioxidative hypoglycemic herbal medicine and diabetes. Methods Some of search terms were “type 2 diabetes”, “antioxidant”, “herb”, “phytotherapy”, “ethnopharmacology”, “Chinese medicine”, “traditional medicine”, in Scopus web databases until January 2015, and limited to human. The collected data were used to generate the specific f...

  10. Medical Subject Headings (MeSH) for indexing and retrieving open-source healthcare data.

    Science.gov (United States)

    Marc, David T; Khairat, Saif S

    2014-01-01

    The US federal government initiated the Open Government Directive where federal agencies are required to publish high value datasets so that they are available to the public. Data.gov and the community site Healthdata.gov were initiated to disperse such datasets. However, data searches and retrieval for these sites are keyword driven and severely limited in performance. The purpose of this paper is to address the issue of extracting relevant open-source data by proposing a method of adopting the MeSH framework for indexing and data retrieval. A pilot study was conducted to compare the performance of traditional keywords to MeSH terms for retrieving relevant open-source datasets related to "mortality". The MeSH framework resulted in greater sensitivity with comparable specificity to the keyword search. MeSH showed promise as a method for indexing and retrieving data, yet future research should conduct a larger scale evaluation of the performance of the MeSH framework for retrieving relevant open-source healthcare datasets.

  11. Constrained and joint inversion on unstructured meshes

    Science.gov (United States)

    Doetsch, J.; Jordi, C.; Rieckh, V.; Guenther, T.; Schmelzbach, C.

    2015-12-01

    Unstructured meshes allow for inclusion of arbitrary surface topography, complex acquisition geometry and undulating geological interfaces in the inversion of geophysical data. This flexibility opens new opportunities for coupling different geophysical and hydrological data sets in constrained and joint inversions. For example, incorporating geological interfaces that have been derived from high-resolution geophysical data (e.g., ground penetrating radar) can add geological constraints to inversions of electrical resistivity data. These constraints can be critical for a hydrogeological interpretation of the inversion results. For time-lapse inversions of geophysical data, constraints can be derived from hydrological point measurements in boreholes, but it is difficult to include these hard constraints in the inversion of electrical resistivity monitoring data. Especially mesh density and the regularization footprint around the hydrological point measurements are important for an improved inversion compared to the unconstrained case. With the help of synthetic and field examples, we analyze how regularization and coupling operators should be chosen for time-lapse inversions constrained by point measurements and for joint inversions of geophysical data in order to take full advantage of the flexibility of unstructured meshes. For the case of constraining to point measurements, it is important to choose a regularization operator that extends beyond the neighboring cells and the uncertainty in the point measurements needs to be accounted for. For joint inversion, the choice of the regularization depends on the expected subsurface heterogeneity and the cell size of the parameter mesh.

  12. Hash functions and triangular mesh reconstruction*1

    Science.gov (United States)

    Hrádek, Jan; Kuchař, Martin; Skala, Václav

    2003-07-01

    Some applications use data formats (e.g. STL file format), where a set of triangles is used to represent the surface of a 3D object and it is necessary to reconstruct the triangular mesh with adjacency information. It is a lengthy process for large data sets as the time complexity of this process is O( N log N), where N is number of triangles. Triangular mesh reconstruction is a general problem and relevant algorithms can be used in GIS and DTM systems as well as in CAD/CAM systems. Many algorithms rely on space subdivision techniques while hash functions offer a more effective solution to the reconstruction problem. Hash data structures are widely used throughout the field of computer science. The hash table can be used to speed up the process of triangular mesh reconstruction but the speed strongly depends on hash function properties. Nevertheless the design or selection of the hash function for data sets with unknown properties is a serious problem. This paper describes a new hash function, presents the properties obtained for large data sets, and discusses validity of the reconstructed surface. Experimental results proved theoretical considerations and advantages of hash function use for mesh reconstruction.

  13. Particle Collection Efficiency for Nylon Mesh Screens.

    Science.gov (United States)

    Cena, Lorenzo G; Ku, Bon-Ki; Peters, Thomas M

    Mesh screens composed of nylon fibers leave minimal residual ash and produce no significant spectral interference when ashed for spectrometric examination. These characteristics make nylon mesh screens attractive as a collection substrate for nanoparticles. A theoretical single-fiber efficiency expression developed for wire-mesh screens was evaluated for estimating the collection efficiency of submicrometer particles for nylon mesh screens. Pressure drop across the screens, the effect of particle morphology (spherical and highly fractal) on collection efficiency and single-fiber efficiency were evaluated experimentally for three pore sizes (60, 100 and 180 μm) at three flow rates (2.5, 4 and 6 Lpm). The pressure drop across the screens was found to increase linearly with superficial velocity. The collection efficiency of the screens was found to vary by less than 4% regardless of particle morphology. Single-fiber efficiency calculated from experimental data was in good agreement with that estimated from theory for particles between 40 and 150 nm but deviated from theory for particles outside this size range. New coefficients for the single-fiber efficiency model were identified that minimized the sum of square error (SSE) between the values estimated with the model and those determined experimentally. Compared to the original theory, the SSE calculated using the modified theory was at least one order of magnitude lower for all screens and flow rates with the exception of the 60-μm pore screens at 2.5 Lpm, where the decrease was threefold.

  14. Mesh Optimization for Ground Vehicle Aerodynamics

    Directory of Open Access Journals (Sweden)

    Adrian Gaylard

    2010-04-01

    Full Text Available

    Mesh optimization strategy for estimating accurate drag of a ground vehicle is proposed based on examining the effect of different mesh parameters.  The optimized mesh parameters were selected using design of experiment (DOE method to be able to work in a limited memory environment and in a reasonable amount of time but without compromising the accuracy of results. The study was further extended to take into account the car model size effect. Three car model sizes have been investigated and compared with MIRA scale wind tunnel results. Parameters that lead to drag value closer to experiment with less memory and computational time have been identified. Scaling the optimized mesh size with the length of car model was successfully used to predict the drag of the other car sizes with reasonable accuracy. This investigation was carried out using STARCCM+ commercial software package, however the findings can be applied to any other CFD package.

  15. Details of tetrahedral anisotropic mesh adaptation

    Science.gov (United States)

    Jensen, Kristian Ejlebjerg; Gorman, Gerard

    2016-04-01

    We have implemented tetrahedral anisotropic mesh adaptation using the local operations of coarsening, swapping, refinement and smoothing in MATLAB without the use of any for- N loops, i.e. the script is fully vectorised. In the process of doing so, we have made three observations related to details of the implementation: 1. restricting refinement to a single edge split per element not only simplifies the code, it also improves mesh quality, 2. face to edge swapping is unnecessary, and 3. optimising for the Vassilevski functional tends to give a little higher value for the mean condition number functional than optimising for the condition number functional directly. These observations have been made for a uniform and a radial shock metric field, both starting from a structured mesh in a cube. Finally, we compare two coarsening techniques and demonstrate the importance of applying smoothing in the mesh adaptation loop. The results pertain to a unit cube geometry, but we also show the effect of corners and edges by applying the implementation in a spherical geometry.

  16. Drag reduction properties of superhydrophobic mesh pipes

    Science.gov (United States)

    Geraldi, Nicasio R.; Dodd, Linzi E.; Xu, Ben B.; Wells, Gary G.; Wood, David; Newton, Michael I.; McHale, Glen

    2017-09-01

    Even with the recent extensive study into superhydrophobic surfaces, the fabrication of such surfaces on the inside walls of a pipe remains challenging. In this work we report a convenient bi-layered pipe design using a thin superhydrophobic metallic mesh formed into a tube, supported inside another pipe. A flow system was constructed to test the fabricated bi-layer pipeline, which allowed for different constant flow rates of water to be passed through the pipe, whilst the differential pressure was measured, from which the drag coefficient (ƒ) and Reynolds numbers (Re) were calculated. Expected values of ƒ were found for smooth glass pipes for the Reynolds number (Re) range 750-10 000, in both the laminar and part of the turbulent regimes. Flow through plain meshes without the superhydrophobic coating were also measured over a similar range (750  superhydrophobic coating, ƒ was found for 4000  superhydrophobic mesh can support a plastron and provide a drag reduction compared to a plain mesh, however, the plastron is progressively destroyed with use and in particular at higher flow rates.

  17. Performance Evaluation of Coded Meshed Networks

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Pedersen, Morten Videbæk;

    2013-01-01

    of the former to enhance the gains of the latter. We first motivate our work through measurements in WiFi mesh networks. Later, we compare state-of-the-art approaches, e.g., COPE, RLNC, to CORE. Our measurements show the higher reliability and throughput of CORE over other schemes, especially, for asymmetric...

  18. Mesh Currents and Josephson Junction Arrays

    OpenAIRE

    1995-01-01

    A simple but accurate mesh current analysis is performed on a XY model and on a SIMF model to derive the equations for a Josephson junction array. The equations obtained here turn out to be different from other equations already existing in the literature. Moreover, it is shown that the two models come from an unique hidden structure

  19. Public Safety Transmitter Towers, Public safety towers controlled by the FCC and combined with all other types of towers., Published in 2006, Johnson County AIMS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Public Safety Transmitter Towers dataset, was produced all or in part from Other information as of 2006. It is described as 'Public safety towers controlled by...

  20. Mechanical biocompatibility of prosthetic meshes: a comprehensive protocol for mechanical characterization.

    Science.gov (United States)

    Maurer, M M; Röhrnbauer, B; Feola, A; Deprest, J; Mazza, E

    2014-12-01

    This study is aimed at a comprehensive and extensive characterization of the mechanical biocompatibility of mesh prostheses. A robust and simple experimental protocol and a set of parameters is proposed, addressing stiffness under uniaxial and biaxial loading conditions, anisotropy, influence of prior deformation history, local mismatch of deformation mechanisms, and changes in mechanical properties when embedded in a homogeneous matrix. These parameters can form the basis for comparison of different mesh types and for evaluation of their mechanical biocompatibility. Measurements were performed on nine mesh types used for hernia and/or pelvic repair, including heavier as well as lighter implants and covering a wide range of mechanical responses. A total of 93 experiments were performed and all parameters are represented for each mesh in a single diagram to facilitate the quantitative assessment of implant characteristics and their comparison. The mechanics of implants is a critical factor determining clinical performance which should be accounted for in mesh selection and for development of future implants.

  1. A progressive mesh method for physical simulations using lattice Boltzmann method on single-node multi-gpu architectures

    CERN Document Server

    Duchateau, Julien; Maquignon, Nicolas; Roussel, Gilles; Renaud, Christophe

    2015-01-01

    In this paper, a new progressive mesh algorithm is introduced in order to perform fast physical simulations by the use of a lattice Boltzmann method (LBM) on a single-node multi-GPU architecture. This algorithm is able to mesh automatically the simulation domain according to the propagation of fluids. This method can also be useful in order to perform various types of simulations on complex geometries. The use of this algorithm combined with the massive parallelism of GPUs allows to obtain very good performance in comparison with the static mesh method used in literature. Several simulations are shown in order to evaluate the algorithm.

  2. Oxidation and degradation of polypropylene transvaginal mesh.

    Science.gov (United States)

    Talley, Anne D; Rogers, Bridget R; Iakovlev, Vladimir; Dunn, Russell F; Guelcher, Scott A

    2017-04-01

    Polypropylene (PP) transvaginal mesh (TVM) repair for stress urinary incontinence (SUI) has shown promising short-term objective cure rates. However, life-altering complications have been associated with the placement of PP mesh for SUI repair. PP degradation as a result of the foreign body reaction (FBR) has been proposed as a contributing factor to mesh complications. We hypothesized that PP oxidizes under in vitro conditions simulating the FBR, resulting in degradation of the PP. Three PP mid-urethral slings from two commercial manufacturers were evaluated. Test specimens (n = 6) were incubated in oxidative medium for up to 5 weeks. Oxidation was assessed by Fourier Transform Infrared Spectroscopy (FTIR), and degradation was evaluated by scanning electron microscopy (SEM). FTIR spectra of the slings revealed evidence of carbonyl and hydroxyl peaks after 5 weeks of incubation time, providing evidence of oxidation of PP. SEM images at 5 weeks showed evidence of surface degradation, including pitting and flaking. Thus, oxidation and degradation of PP pelvic mesh were evidenced by chemical and physical changes under simulated in vivo conditions. To assess changes in PP surface chemistry in vivo, fibers were recovered from PP mesh explanted from a single patient without formalin fixation, untreated (n = 5) or scraped (n = 5) to remove tissue, and analyzed by X-ray photoelectron spectroscopy. Mechanical scraping removed adherent tissue, revealing an underlying layer of oxidized PP. These findings underscore the need for further research into the relative contribution of oxidative degradation to complications associated with PP-based TVM devices in larger cohorts of patients.

  3. Wireless Mesh Network Routing Under Uncertain Demands

    Science.gov (United States)

    Wellons, Jonathan; Dai, Liang; Chang, Bin; Xue, Yuan

    Traffic routing plays a critical role in determining the performance of a wireless mesh network. Recent research results usually fall into two ends of the spectrum. On one end are the heuristic routing algorithms, which are highly adaptive to the dynamic environments of wireless networks yet lack the analytical properties of how well the network performs globally. On the other end are the optimal routing algorithms that are derived from the optimization problem formulation of mesh network routing. They can usually claim analytical properties such as resource use optimality and throughput fairness. However, traffic demand is usually implicitly assumed as static and known a priori in these problem formulations. In contrast, recent studies of wireless network traces show that the traffic demand, even being aggregated at access points, is highly dynamic and hard to estimate. Thus, to apply the optimization-based routing solution in practice, one must take into account the dynamic and uncertain nature of wireless traffic demand. There are two basic approaches to address the traffic uncertainty in optimal mesh network routing (1) predictive routing that infers the traffic demand with maximum possibility based in its history and optimizes the routing strategy based on the predicted traffic demand and (2) oblivious routing that considers all the possible traffic demands and selects the routing strategy where the worst-case network performance could be optimized. This chapter provides an overview of the optimal routing strategies for wireless mesh networks with a focus on the above two strategies that explicitly consider the traffic uncertainty. It also identifies the key factors that affect the performance of each routing strategy and provides guidelines towards the strategy selection in mesh network routing under uncertain traffic demands.

  4. The mesh-matching algorithm: an automatic 3D mesh generator for Finite element structures

    CERN Document Server

    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.

  5. Randomized clinical trial of self-gripping mesh versus sutured mesh for Lichtenstein hernia repair

    DEFF Research Database (Denmark)

    Jorgensen, L N; Sommer, T; Assaadzadeh, S;

    2012-01-01

    between the groups in postoperative complications (33·7 versus 40·4 per cent; P = 0·215), rate of recurrent hernia within 1 year (1·2 per cent in both groups) or quality of life. CONCLUSION: The avoidance of suture fixation using a self-gripping mesh was not accompanied by a reduction in chronic symptoms......BACKGROUND: Many patients develop discomfort after open repair of a groin hernia. It was hypothesized that suture fixation of the mesh is a cause of these symptoms. METHODS: This patient- and assessor-blinded randomized multicentre clinical trial compared a self-gripping mesh (Parietene Progrip......(®) ) and sutured mesh for open primary repair of uncomplicated inguinal hernia by the Lichtenstein technique. Patients were assessed before surgery, on the day of operation, and at 1 and 12 months after surgery. The primary endpoint was moderate or severe symptoms after 12 months, including a combination...

  6. Moving mesh generation with a sequential approach for solving PDEs

    DEFF Research Database (Denmark)

    of 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...... 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.......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...

  7. CUBIT mesh generation environment. Volume 1: Users manual

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. On combining Laplacian and optimization-based mesh smoothing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Freitag, L.A.

    1997-07-01

    Local mesh smoothing algorithms have been shown to be effective in repairing distorted elements in automatically generated meshes. The simplest such algorithm is Laplacian smoothing, which moves grid points to the geometric center of incident vertices. Unfortunately, this method operates heuristically and can create invalid meshes or elements of worse quality than those contained in the original mesh. In contrast, optimization-based methods are designed to maximize some measure of mesh quality and are very effective at eliminating extremal angles in the mesh. These improvements come at a higher computational cost, however. In this article the author proposes three smoothing techniques that combine a smart variant of Laplacian smoothing with an optimization-based approach. Several numerical experiments are performed that compare the mesh quality and computational cost for each of the methods in two and three dimensions. The author finds that the combined approaches are very cost effective and yield high-quality meshes.

  9. INCISIONAL HERNIA - ONLAY VS SUBLAY MESH HERNIOPLAS T Y

    OpenAIRE

    Ravi Kamal Kumar; Chandrakumar; Vijayalaxmi,; Thokala; Venkat Ramana

    2015-01-01

    BACKGROUND : Incisional hernia is a common surgical problem. Anatomical repair of hernia is now out of vogue. Polypropylene mesh repair has now become accepted. In open mesh repair of incisional hernia cases the site of placement of mesh is still debated. Some surgeo ns favour the onlay repair and others use sublay or retro - rectus plane for deployment of the mesh. AIM: The aim of the study is to examine the pros and cons of both the techniques and find the bett...

  10. Explicit inverse distance weighting mesh motion for coupled problems

    OpenAIRE

    Witteveen, J.A.S.; Bijl, H.

    2009-01-01

    An explicit mesh motion algorithm based on inverse distance weighting interpolation is presented. The explicit formulation leads to a fast mesh motion algorithm and an easy implementation. In addition, the proposed point-by-point method is robust and flexible in case of large deformations, hanging nodes, and parallelization. Mesh quality results and CPU time comparisons are presented for triangular and hexahedral unstructured meshes in an airfoil flutter fluid-structure interaction problem.

  11. On Reducing Delay in Mesh-Based P2P Streaming: A Mesh-Push Approach

    Science.gov (United States)

    Liu, Zheng; Xue, Kaiping; Hong, Peilin

    The peer-assisted streaming paradigm has been widely employed to distribute live video data on the internet recently. In general, the mesh-based pull approach is more robust and efficient than the tree-based push approach. However, pull protocol brings about longer streaming delay, which is caused by the handshaking process of advertising buffer map message, sending request message and scheduling of the data block. In this paper, we propose a new approach, mesh-push, to address this issue. Different from the traditional pull approach, mesh-push implements block scheduling algorithm at sender side, where the block transmission is initiated by the sender rather than by the receiver. We first formulate the optimal upload bandwidth utilization problem, then present the mesh-push approach, in which a token protocol is designed to avoid block redundancy; a min-cost flow model is employed to derive the optimal scheduling for the push peer; and a push peer selection algorithm is introduced to reduce control overhead. Finally, we evaluate mesh-push through simulation, the results of which show mesh-push outperforms the pull scheduling in streaming delay, and achieves comparable delivery ratio at the same time.

  12. A testing preocedure for the evaluation of directional mesh bias

    NARCIS (Netherlands)

    Slobbe, A.T.; Hendriks, M.A.N.; Rots, J.G.

    2013-01-01

    This paper presents a dedicated numerical test that enables to assess the directional mesh bias of constitutive models in a systematic way. The test makes use of periodic boundary conditions, by which strain localization can be analyzed for different mesh alignments with preservation of mesh uniform

  13. Multiphase flow of immiscible fluids on unstructured moving meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam

    2012-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization op...

  14. 21 CFR 870.3650 - Pacemaker polymeric mesh bag.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

  15. [Counterfeit phosphodiesterase type 5 inhibitors--growing safety risks for public health].

    Science.gov (United States)

    Fijałek, Zbigniew; Sarna, Katarzyna; Błazewicz, Agata; Marin, Jan

    2010-01-01

    Counterfeit drugs, medical devises and dietary supplements are inherently dangerous and a growing problem. In Europe the growth of the counterfeit medication market is attributable in part to registration of phosphodiesterase type 5 inhibitors (PDE-5) used for the erectile dysfunction. "Viagra, Levitra and Cialis belong to this group. It has been estimated that up to 2.5 million men in Europe are exposed to an illicit sildenafil, suggesting that there may be as many illegal as legal users of sildenafil. In Europe a strong trend is observed towards increasingly professional counterfeits and imitations of Viagra, Cialis and Levitra, with regard to the appearance of tablets, capsules and packaging. The professional presentation will deceive potential consumers into assuming these products are legal, efficacious and safe. Globally, increased obstacles for counterfeiters are necessary to combat pharmaceutical counterfeiting, including fines and penalties. The worldwide nature of the counterfeit problem requires proper coordination between countries to ensure an adequate enforcement. We described the usefulness of the time-of-flight mass spectrometry with the electrospray ionization (LC-ESI-MS-TOF) and the X-ray powder diffraction method (XRPD) for PDE-5 counterfeit screening from the Polish illegal market.

  16. Solitonic-type excitations in laser-condensed matter interaction: additional proof by independent publications

    Science.gov (United States)

    Kudriavtsev, Eugene M.

    2000-08-01

    The goal of this report is to discuss (in addition to review) the independent literature works which come to our attention in 2 last years with experimental or theoretical proofs the existence of the solitonic type Wave of Change in Reflection and Conduction (WCRC). WCRC presents a new variety of transfer phenomena in condensed matter. It was excited by a single IR laser pulse with a threshold of more than 10 kW/cm2 and consists of a series of about 30 solitary pulses with propagation velocity of each subsequent pulse decreasing two times comparing with that of preceding one in the range from sound velocity to less than about micron/s. Each pulse has the following solitary wave features: (1) it is all the time of one sign, (2) its velocity Ui is nearly constant, (3) it reflects from sample surfaces without noticeable velocity change. So far the systematic WCRC study was made in Lebedev Physical Institute, grate deal in collaboration with group of Marseilles University (prof. M. Autric) and also with some others groups. Literature analysis showed independent works where WCRC can be seen and which was made in different institutions with different own goals in mind. As example, work on optical monitoring of laser damage in IR materials or thermocouple measurements of temperature non stability in water cooled copper shield stopped the high power e-beam, etc. We will discuss also some details of theoretical work connected with development of Frenkel-Kontorova (1937) topological soliton model. WCRC is rather universal phenomenon, it appears in many laser-condensed matter interactions and so it should be studied for the WCRC mechanism understanding and its effect evaluation for different applications.

  17. To mesh or not to mesh: a review of pelvic organ reconstructive surgery

    Directory of Open Access Journals (Sweden)

    Dällenbach P

    2015-04-01

    Full Text Available Patrick Dällenbach Department of Gynecology and Obstetrics, Division of Gynecology, Urogynecology Unit, Geneva University Hospitals, Geneva, Switzerland Abstract: Pelvic organ prolapse (POP is a major health issue with a lifetime risk of undergoing at least one surgical intervention estimated at close to 10%. In the 1990s, the risk of reoperation after primary standard vaginal procedure was estimated to be as high as 30% to 50%. In order to reduce the risk of relapse, gynecological surgeons started to use mesh implants in pelvic organ reconstructive surgery with the emergence of new complications. Recent studies have nevertheless shown that the risk of POP recurrence requiring reoperation is lower than previously estimated, being closer to 10% rather than 30%. The development of mesh surgery – actively promoted by the marketing industry – was tremendous during the past decade, and preceded any studies supporting its benefit for our patients. Randomized trials comparing the use of mesh to native tissue repair in POP surgery have now shown better anatomical but similar functional outcomes, and meshes are associated with more complications, in particular for transvaginal mesh implants. POP is not a life-threatening condition, but a functional problem that impairs quality of life for women. The old adage “primum non nocere” is particularly appropriate when dealing with this condition which requires no treatment when asymptomatic. It is currently admitted that a certain degree of POP is physiological with aging when situated above the landmark of the hymen. Treatment should be individualized and the use of mesh needs to be selective and appropriate. Mesh implants are probably an important tool in pelvic reconstructive surgery, but the ideal implant has yet to be found. The indications for its use still require caution and discernment. This review explores the reasons behind the introduction of mesh augmentation in POP surgery, and aims to

  18. Effects of glass fiber mesh with different fiber content and structures on the compressive properties of complete dentures.

    Science.gov (United States)

    Yu, Sang-Hui; Cho, Hye-Won; Oh, Seunghan; Bae, Ji-Myung

    2015-06-01

    No study has yet evaluated the strength of complete dentures reinforced with glass fiber meshes with different content and structures. The purpose of this study was to compare the reinforcing effects of glass fiber mesh with different content and structures with that of metal mesh in complete dentures. Two types of glass fiber mesh were used: SES mesh (SES) and glass cloth (GC2, GC3, and GC4). A metal mesh was used for comparison. The complete dentures were made by placing the reinforcement 1 mm away from the tissue surface. A control group was prepared without any reinforcement (n=10). The compressive properties were measured by a universal testing machine at a crosshead speed of 5 mm/min. The results were analyzed with the Kruskal-Wallis test and the Duncan multiple range test (α=.05). The fracture resistance of the SES group was significantly higher than that of the control, GC4, and metal groups (asymptotic P=.004), but not significantly different from the GC2 and GC3 groups. The toughness of the SES and GC3 groups was significantly higher than that of the others (asymptotic Pcomplete dentures. The content of the glass fiber mesh seemed more important than the structures. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Energy-aware path selection metric for IEEE 802.11s wireless mesh networking

    CSIR Research Space (South Africa)

    Mhlanga, MM

    2009-08-01

    Full Text Available , there are various types of restrictions. The biggest restriction is the confined energy of the batteries. Thus, energy consumption is crucial in the design of new mesh routing protocols. This paper presents a new energy-aware routing metric for HWMP to balance...

  20. Is Mesh Becoming More Popular? Dilemmas in Urogynecology: A National Survey

    Directory of Open Access Journals (Sweden)

    Alexander Condrea

    2012-01-01

    Full Text Available The use of vaginal mesh in pelvic organ prolapse (POP repair surgery has become more common in recent years. The purpose of the current study was to evaluate the common practice of Israeli urogynecologists, and to determine whether surgical practice has changed over the last two years. Methods. In 2009 and again in 2011, a survey was mailed to all urogynecologists affiliated with an academic institute in Israel. The survey consisted of 7 Likert-scale items and 3 open questions; the latter inquired about preferred type of surgery in three clinical scenarios. Results. Of 22 practitioners, 15 responded to the survey. The number of urogynecologists who reported using vaginal mesh for the repair of primary POP increased from 47 to 67% from 2009 to 2011. The number who would not use vaginal mesh in POP repair of elderly patients dropped from 60 to 3%. Finally, for the treatment of a 35-year-old patient with stage III uterine prolapse who desired to preserve fertility, 13% recommended the used vaginal mesh in 2009 compared with 47% in 2011. Conclusion. A survey of practitioners shows that the use of vaginal mesh for the repair of primary and recurrent pelvic organ prolapse has become more common among Israeli urogynecologists.

  1. Coupling codes including deformation exchange suitable for non conforming and unstructured large meshes

    Energy Technology Data Exchange (ETDEWEB)

    Duplex, B., E-mail: benjamin.duplex@gmail.fr [CEA, DEN, DANS/DM2S/STMF, Cadarache, F-13108 Saint-Paul-lez-Durance (France); Grandotto, M. [CEA, DEN, DANS/DM2S/STMF, Cadarache, F-13108 Saint-Paul-lez-Durance (France); Perdu, F. [CEA, DEN, DANS/DM2S/STMF, 17 rue des Martyrs, F-38054 Grenoble (France); Daniel, M.; Gesquiere, G. [Aix-Marseille University, CNRS, LSIS, UMR 7296, case postale 925, 163 Avenue de Luminy, F-13288 Marseille cedex 09 (France)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer A function of deformation transfer on meshes is proposed. Black-Right-Pointing-Pointer Large meshes sharing a common geometry or common borders are treated. Black-Right-Pointing-Pointer We show the deformation transfer impact on simulation results. - Abstract: The paper proposes a method to couple computation codes and focuses on the transfer of mesh deformations between these codes. The deformations can concern a single object or different objects in contact along common boundaries. The method is designed to allow a wide range of mesh types and to manage large volumes of data. To reach these objectives, a mesh simplification step is first achieved and is followed by the deformation characterisation through a continuous function defined by a network of compact support radial basis functions (RBFs). A test case featuring adjacent geometries in a material testing reactor (MTR) is presented to assess the method. Two solids close together are subject to a deformation by a thermal dilatation, and are cooled by a liquid flowing between them. The results demonstrate the effectiveness of the method and show how the deformation transfer modifies the thermalhydraulic solution.

  2. On the Feasibility of Wireless Multimedia Sensor Networks over IEEE 802.15.5 Mesh Topologies.

    Science.gov (United States)

    Garcia-Sanchez, Antonio-Javier; Losilla, Fernando; Rodenas-Herraiz, David; Cruz-Martinez, Felipe; Garcia-Sanchez, Felipe

    2016-05-05

    Wireless Multimedia Sensor Networks (WMSNs) are a special type of Wireless Sensor Network (WSN) where large amounts of multimedia data are transmitted over networks composed of low power devices. Hierarchical routing protocols typically used in WSNs for multi-path communication tend to overload nodes located within radio communication range of the data collection unit or data sink. The battery life of these nodes is therefore reduced considerably, requiring frequent battery replacement work to extend the operational life of the WSN system. In a wireless sensor network with mesh topology, any node may act as a forwarder node, thereby enabling multiple routing paths toward any other node or collection unit. In addition, mesh topologies have proven advantages, such as data transmission reliability, network robustness against node failures, and potential reduction in energy consumption. This work studies the feasibility of implementing WMSNs in mesh topologies and their limitations by means of exhaustive computer simulation experiments. To this end, a module developed for the Synchronous Energy Saving (SES) mode of the IEEE 802.15.5 mesh standard has been integrated with multimedia tools to thoroughly test video sequences encoded using H.264 in mesh networks.

  3. A GENERATIVE CAD MODEL OF A WORM GEAR MESHING

    Directory of Open Access Journals (Sweden)

    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.

  4. Production-quality Tools for Adaptive Mesh RefinementVisualization

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Gunther H.; Childs, Hank; Bonnell, Kathleen; Meredith,Jeremy; Miller, Mark; Whitlock, Brad; Bethel, E. Wes

    2007-10-25

    Adaptive Mesh Refinement (AMR) is a highly effectivesimulation method for spanning a large range of spatiotemporal scales,such as astrophysical simulations that must accommodate ranges frominterstellar to sub-planetary. Most mainstream visualization tools stilllack support for AMR as a first class data type and AMR code teams usecustom built applications for AMR visualization. The Department ofEnergy's (DOE's) Science Discovery through Advanced Computing (SciDAC)Visualization and Analytics Center for Enabling Technologies (VACET) isextending and deploying VisIt, an open source visualization tool thataccommodates AMR as a first-class data type, for use asproduction-quality, parallel-capable AMR visual data analysisinfrastructure. This effort will help science teams that use AMR-basedsimulations and who develop their own AMR visual data analysis softwareto realize cost and labor savings.

  5. Selective separation of oil and water with mesh membranes by capillarity

    KAUST Repository

    Yu, Yuanlie

    2016-05-29

    The separation of oil and water from wastewater generated in the oil-production industries, as well as in frequent oil spillage events, is important in mitigating severe environmental and ecological damage. Additionally, a wide arrange of industrial processes require oils or fats to be removed from aqueous systems. The immiscibility of oil and water allows for the wettability of solid surfaces to be engineered to achieve the separation of oil and water through capillarity. Mesh membranes with extreme, selective wettability can efficiently remove oil or water from oil/water mixtures through a simple filtration process using gravity. A wide range of different types of mesh membranes have been successfully rendered with extreme wettability and applied to oil/water separation in the laboratory. These mesh materials have typically shown good durability, stability as well as reusability, which makes them promising candidates for an ever widening range of practical applications. © 2016 Elsevier B.V.

  6. Creating wi-fi bluetooth mesh network for crisis management applications

    Science.gov (United States)

    Al-Tekreeti, Safa; Adams, Christopher; Al-Jawad, Naseer

    2010-04-01

    This paper proposes a wireless mesh network implementation consisting of both Wi-Fi Ad-Hoc networks as well as Bluetooth Piconet/Scatternet networks, organised in an energy and throughput efficient structure. This type of networks can be easily constructed for Crises management applications, for example in an Earthquake disaster. The motivation of this research is to form mesh network from the mass availability of WiFi and Bluetooth enabled electronic devices such as mobile phones and PC's that are normally present in most regions were major crises occurs. The target of this study is to achieve an effective solution that will enable Wi-Fi and/or Bluetooth nodes to seamlessly configure themselves to act as a bridge between their own network and that of the other network to achieve continuous routing for our proposed mesh networks.

  7. Automatic off-body overset adaptive Cartesian mesh method based on an octree approach

    Energy Technology Data Exchange (ETDEWEB)

    Peron, Stephanie, E-mail: stephanie.peron@onera.fr [ONERA - The French Aerospace Lab, F-92322 Chatillon (France); Benoit, Christophe, E-mail: christophe.benoit@onera.fr [ONERA - The French Aerospace Lab, F-92322 Chatillon (France)

    2013-01-01

    This paper describes a method for generating adaptive structured Cartesian grids within a near-body/off-body mesh partitioning framework for the flow simulation around complex geometries. The off-body Cartesian mesh generation derives from an octree structure, assuming each octree leaf node defines a structured Cartesian block. This enables one to take into account the large scale discrepancies in terms of resolution between the different bodies involved in the simulation, with minimum memory requirements. Two different conversions from the octree to Cartesian grids are proposed: the first one generates Adaptive Mesh Refinement (AMR) type grid systems, and the second one generates abutting or minimally overlapping Cartesian grid set. We also introduce an algorithm to control the number of points at each adaptation, that automatically determines relevant values of the refinement indicator driving the grid refinement and coarsening. An application to a wing tip vortex computation assesses the capability of the method to capture accurately the flow features.

  8. Selective separation of oil and water with mesh membranes by capillarity.

    Science.gov (United States)

    Yu, Yuanlie; Chen, Hua; Liu, Yun; Craig, Vincent S J; Lai, Zhiping

    2016-09-01

    The separation of oil and water from wastewater generated in the oil-production industries, as well as in frequent oil spillage events, is important in mitigating severe environmental and ecological damage. Additionally, a wide arrange of industrial processes require oils or fats to be removed from aqueous systems. The immiscibility of oil and water allows for the wettability of solid surfaces to be engineered to achieve the separation of oil and water through capillarity. Mesh membranes with extreme, selective wettability can efficiently remove oil or water from oil/water mixtures through a simple filtration process using gravity. A wide range of different types of mesh membranes have been successfully rendered with extreme wettability and applied to oil/water separation in the laboratory. These mesh materials have typically shown good durability, stability as well as reusability, which makes them promising candidates for an ever widening range of practical applications.

  9. Meshed split skin graft for extensive vitiligo

    Directory of Open Access Journals (Sweden)

    Srinivas C

    2004-05-01

    Full Text Available A 30 year old female presented with generalized stable vitiligo involving large areas of the body. Since large areas were to be treated it was decided to do meshed split skin graft. A phototoxic blister over recipient site was induced by applying 8 MOP solution followed by exposure to UVA. The split skin graft was harvested from donor area by Padgett dermatome which was meshed by an ampligreffe to increase the size of the graft by 4 times. Significant pigmentation of the depigmented skin was seen after 5 months. This procedure helps to cover large recipient areas, when pigmented donor skin is limited with minimal risk of scarring. Phototoxic blister enables easy separation of epidermis thus saving time required for dermabrasion from recipient site.

  10. Variational mesh segmentation via quadric surface fitting

    KAUST Repository

    Yan, Dongming

    2012-11-01

    We present a new variational method for mesh segmentation by fitting quadric surfaces. Each component of the resulting segmentation is represented by a general quadric surface (including plane as a special case). A novel energy function is defined to evaluate the quality of the segmentation, which combines both L2 and L2 ,1 metrics from a triangle to a quadric surface. The Lloyd iteration is used to minimize the energy function, which repeatedly interleaves between mesh partition and quadric surface fitting. We also integrate feature-based and simplification-based techniques in the segmentation framework, which greatly improve the performance. The advantages of our algorithm are demonstrated by comparing with the state-of-the-art methods. © 2012 Elsevier Ltd. All rights reserved.

  11. Capacity estimation of wireless mesh networks

    OpenAIRE

    2005-01-01

    Resumo: Este trabalho apresenta uma estimação da capacidade das redes sem fio tipo Mesh. As redes deste tipo têm topologias e padrões de tráfego únicos que as diferenciam das redes sem fio convencionais. Nas redes sem fio tipo mesh os nós atuam como clientes e como servidores e o tráfego e encaminhado para uma ou várias gateways em um modo multi-salto. A estimação da capacidade é baseada em estudos da Camada Física e MAC. Efeitos da propagação do canal são avaliados Abstract: This work add...

  12. Nondispersive optical activity of meshed helical metamaterials.

    Science.gov (United States)

    Park, Hyun Sung; Kim, Teun-Teun; Kim, Hyeon-Don; Kim, Kyungjin; Min, Bumki

    2014-11-17

    Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45° per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

  13. Energy-efficient wireless mesh networks

    CSIR Research Space (South Africa)

    Ntlatlapa, N

    2007-06-01

    Full Text Available ­deficient areas such as rural areas in  Africa.  Index   Terms—Energy   efficient   design,   Wireless  Mesh networks, Network Protocols I. INTRODUCTION The  objectives  of   this   research  group   are   the  application   and   adaptation   of   existing   wireless  local   area...   networks,   especially   those   based   on  802.11 standard, for   the energy­efficient  wireless  mesh network (EE­WMN) architectures, protocols  and   controls.   In   addition   to   the   WMN   regular  features   of   self...

  14. Adaptive upscaling with the dual mesh method

    Energy Technology Data Exchange (ETDEWEB)

    Guerillot, D.; Verdiere, S.

    1997-08-01

    The objective of this paper is to demonstrate that upscaling should be calculated during the flow simulation instead of trying to enhance the a priori upscaling methods. Hence, counter-examples are given to motivate our approach, the so-called Dual Mesh Method. The main steps of this numerical algorithm are recalled. Applications illustrate the necessity to consider different average relative permeability values depending on the direction in space. Moreover, these values could be different for the same average saturation. This proves that an a priori upscaling cannot be the answer even in homogeneous cases because of the {open_quotes}dynamical heterogeneity{close_quotes} created by the saturation profile. Other examples show the efficiency of the Dual Mesh Method applied to heterogeneous medium and to an actual field case in South America.

  15. Gamra: Simple Meshes for Complex Earthquakes

    CERN Document Server

    Landry, Walter

    2016-01-01

    The static offsets caused by earthquakes are well described by elastostatic models with a discontinuity in the displacement along the fault. A traditional approach to model this discontinuity is to align the numerical mesh with the fault and solve the equations using finite elements. However, this distorted mesh can be difficult to generate and update. We present a new numerical method, inspired by the Immersed Interface Method, for solving the elastostatic equations with embedded discontinuities. This method has been carefully designed so that it can be used on parallel machines on an adapted finite difference grid. We have implemented this method in Gamra, a new code for earth modelling. We demonstrate the correctness of the method with analytic tests, and we demonstrate its practical performance by solving a realistic earthquake model to extremely high precision.

  16. Electrostatic PIC with adaptive Cartesian mesh

    CERN Document Server

    Kolobov, Vladimir I

    2016-01-01

    We describe an initial implementation of an electrostatic Particle-in-Cell (ES-PIC) module with adaptive Cartesian mesh in our Unified Flow Solver framework. Challenges of PIC method with cell-based adaptive mesh refinement (AMR) are related to a decrease of the particle-per-cell number in the refined cells with a corresponding increase of the numerical noise. The developed ES-PIC solver is validated for capacitively coupled plasma, its AMR capabilities are demonstrated for simulations of streamer development during high-pressure gas breakdown. It is shown that cell-based AMR provides a convenient particle management algorithm for exponential multiplications of electrons and ions in the ionization events.

  17. Mesh convergence study for hydraulic turbine draft-tube

    Science.gov (United States)

    Devals, C.; Vu, T. C.; Zhang, Y.; Dompierre, J.; Guibault, F.

    2016-11-01

    Computational flow analysis is an essential tool for hydraulic turbine designers. Grid generation is the first step in the flow analysis process. Grid quality and solution accuracy are strongly linked. Even though many studies have addressed the issue of mesh independence, there is still no definitive consensus on mesh best practices, and research on that topic is still needed. This paper presents a mesh convergence study for turbulence flow in hydraulic turbine draft- tubes which represents the most challenging turbine component for CFD predictions. The findings from this parametric study will be incorporated as mesh control rules in an in-house automatic mesh generator for turbine components.

  18. Overlay Share Mesh for Interactive Group Communication with High Dynamic

    Institute of Scientific and Technical Information of China (English)

    WU Yan-hua; CAI Yun-ze; XU Xiao-ming

    2007-01-01

    An overlay share mesh infrastructure is presented for high dynamic group communication systems, such as distributed interactive simulation (DIS) and distributed virtual environments (DVE). Overlay share mesh infrastructure can own better adapting ability for high dynamic group than tradition multi-tree multicast infrastructure by sharing links among different groups. The mechanism of overlay share mesh based on area of interest (AOI) was discussed in detail in this paper. A large number of simulation experiments were done and the permance of mesh infrastructure was studied. Experiments results proved that overlay mesh infrastructure owns better adaptability than traditional multi-tree infrastructure for high dynamic group communication systems.

  19. Diffusive mesh relaxation in ALE finite element numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dube, E.I.

    1996-06-01

    The theory for a diffusive mesh relaxation algorithm is developed for use in three-dimensional Arbitary Lagrange/Eulerian (ALE) finite element simulation techniques. This mesh relaxer is derived by a variational principle for an unstructured 3D grid using finite elements, and incorporates hourglass controls in the numerical implementation. The diffusive coefficients are based on the geometric properties of the existing mesh, and are chosen so as to allow for a smooth grid that retains the general shape of the original mesh. The diffusive mesh relaxation algorithm is then applied to an ALE code system, and results from several test cases are discussed.

  20. Effects of mesh resolution on hypersonic heating prediction

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Aeroheating prediction is a challenging and critical problem for the design and optimization of hypersonic vehicles.One challenge is that the solution of the Navier-Stokes equations strongly depends on the computational mesh.In this letter,the effect of mesh resolution on heat flux prediction is studied.It is found that mesh-independent solutions can be obtained using fine mesh,whose accuracy is confirmed by results from kinetic particle simulation.It is analyzed that mesh-induced numerical error comes m...

  1. Wireless experiments on a Motorola mesh testbed.

    Energy Technology Data Exchange (ETDEWEB)

    Riblett, Loren E., Jr.; Wiseman, James M.; Witzke, Edward L.

    2010-06-01

    Motomesh is a Motorola product that performs mesh networking at both the client and access point levels and allows broadband mobile data connections with or between clients moving at vehicular speeds. Sandia National aboratories has extensive experience with this product and its predecessors in infrastructure-less mobile environments. This report documents experiments, which characterize certain aspects of how the Motomesh network performs when obile units are added to a fixed network infrastructure.

  2. Airbag Mapped Mesh Auto-Flattening Method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jinhuan; MA Chunsheng; BAI Yuanli; HUANG Shilin

    2005-01-01

    Current software cannot easily model an airbag to be flattened without wrinkles. This paper improves the modeling efficiency using the initial metric method to design a mapped mesh auto-flattening algorithm. The element geometric transformation matrix was obtained using the theory of computer graphics. The algorithm proved to be practical for modeling a passenger-side airbag model. The efficiency and precision of modeling airbags are greatly improved by this method.

  3. Gradient Domain Mesh Deformation - A Survey

    Institute of Scientific and Technical Information of China (English)

    Wei-Wei Xu; Kun Zhou

    2009-01-01

    This survey reviews the recent development of gradient domain mesh deformation method. Different to other deformation methods, the gradient domain deformation method is a surface-based, variational optimization method. It directly encodes the geometric details in differential coordinates, which are also called Laplacian coordinates in literature. By preserving the Laplacian coordinates, the mesh details can be well preserved during deformation. Due to the locality of the Laplacian coordinates, the variational optimization problem can be casted into a sparse linear system. Fast sparse linear solver can be adopted to generate deformation result interactively, or even in real-time. The nonlinear nature of gradient domain mesh deformation leads to the development of two categories of deformation methods: linearization methods and nonlinear optimization methods. Basically, the linearization methods only need to solve the linear least-squares system once. They are fast, easy to understand and control, while the deformation result might be suboptimal. Nonlinear optimization methods can reach optimal solution of deformation energy function by iterative updating. Since the computation of nonlinear methods is expensive, reduced deformable models should be adopted to achieve interactive performance. The nonlinear optimization methods avoid the user burden to input transformation at deformation handles, and they can be extended to incorporate various nonlinear constraints, like volume constraint, skeleton constraint, and so on. We review representative methods and related approaches of each category comparatively and hope to help the user understand the motivation behind the algorithms. Finally, we discuss the relation between physical simulation and gradient domain mesh deformation to reveal why it can achieve physically plausible deformation result.

  4. Solid Mesh Registration for Radiotherapy Treatment Planning

    DEFF Research Database (Denmark)

    Noe, Karsten Østergaard; Sørensen, Thomas Sangild

    2010-01-01

    We present an algorithm for solid organ registration of pre-segmented data represented as tetrahedral meshes. Registration of the organ surface is driven by force terms based on a distance field representation of the source and reference shapes. Registration of internal morphology is achieved usi...... to complete. The proposed method has many potential uses in image guided radiotherapy (IGRT) which relies on registration to account for organ deformation between treatment sessions....

  5. Performance Evaluation of Coded Meshed Networks

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Pedersen, Morten Videbæk

    2013-01-01

    of the former to enhance the gains of the latter. We first motivate our work through measurements in WiFi mesh networks. Later, we compare state-of-the-art approaches, e.g., COPE, RLNC, to CORE. Our measurements show the higher reliability and throughput of CORE over other schemes, especially, for asymmetric...... and/or high loss probabilities. We show that a store and forward scheme outperforms COPE under some channel conditions, while CORE yields 3dB gains....

  6. Occurrence of Clostridium perfringens Types A, E, and C in Fresh Fish and Its Public Health Significance.

    Science.gov (United States)

    Sabry, Maha; Abd El-Moein, Khaled; Hamza, Eman; Abdel Kader, Fatma

    2016-06-01

    Fish remains among the most traded of food commodities, and Egypt is one of the emerging countries being recognized as an important world fish exporter. Clostridium perfringens is an important foodborne pathogen to consider in fish trade, as it has been implicated as the causative organism of two fish outbreaks. The aim of the present study was to investigate the occurrence and toxin diversity of C. perfringens associated with fresh and canned fish and to examine the public health significance of C. perfringens infection in fish. Isolation and identification of C. perfringens showed a significantly higher prevalence of the bacterium in fresh fish collected from aquaculture (54.5%) and from markets (71%) as well as in humans in contact with fish (63%) compared with water used for keeping fresh fish (27.3%) and water used in canned fish (17.8%). The isolation level was significantly higher in samples from the external surface of fresh fish (31.8% in aquaculture, 45.6% in markets) than from the intestinal contents of the same fish (9.1% in aquaculture, 6.7% in markets). Thus, markets represent a risk factor for contamination of the external surface of fish from the surrounding environment. Genotyping of the C. perfringens-positive isolates by using multiplex PCR revealed that type A enterotoxin-negative (CPE(-)) is the predominant strain among fish (fresh and canned), humans, and water in contact with fresh fish. Interestingly, C. perfringens types A enterotoxin-positive (CPE(+)) and C were found only in fresh fish, and these two strains have great health importance in humans. Strikingly, C. perfringens type E strain was detected for the first time in fish, humans, and water in contact with fresh fish. Our results demonstrate for the first time that fish act as a reservoir for C. perfringens, particularly for types A CPE(+), C, and E. The external surface of fish represents a vehicle for contamination of fish from the surrounding environment as well as a source of

  7. Particle Mesh Hydrodynamics for Astrophysics Simulations

    Science.gov (United States)

    Chatelain, Philippe; Cottet, Georges-Henri; Koumoutsakos, Petros

    We present a particle method for the simulation of three dimensional compressible hydrodynamics based on a hybrid Particle-Mesh discretization of the governing equations. The method is rooted on the regularization of particle locations as in remeshed Smoothed Particle Hydrodynamics (rSPH). The rSPH method was recently introduced to remedy problems associated with the distortion of computational elements in SPH, by periodically re-initializing the particle positions and by using high order interpolation kernels. In the PMH formulation, the particles solely handle the convective part of the compressible Euler equations. The particle quantities are then interpolated onto a mesh, where the pressure terms are computed. PMH, like SPH, is free of the convection CFL condition while at the same time it is more efficient as derivatives are computed on a mesh rather than particle-particle interactions. PMH does not detract from the adaptive character of SPH and allows for control of its accuracy. We present simulations of a benchmark astrophysics problem demonstrating the capabilities of this approach.

  8. Mesh Learning for Classifying Cognitive Processes

    CERN Document Server

    Ozay, Mete; Öztekin, Uygar; Vural, Fatos T Yarman

    2012-01-01

    The major goal of this study is to model the encoding and retrieval operations of the brain during memory processing, using statistical learning tools. The suggested method assumes that the memory encoding and retrieval processes can be represented by a supervised learning system, which is trained by the brain data collected from the functional Magnetic Resonance (fMRI) measurements, during the encoding stage. Then, the system outputs the same class labels as that of the fMRI data collected during the retrieval stage. The most challenging problem of modeling such a learning system is the design of the interactions among the voxels to extract the information about the underlying patterns of brain activity. In this study, we suggest a new method called Mesh Learning, which represents each voxel by a mesh of voxels in a neighborhood system. The nodes of the mesh are a set of neighboring voxels, whereas the arc weights are estimated by a linear regression model. The estimated arc weights are used to form Local Re...

  9. Parallel object-oriented adaptive mesh refinement

    Energy Technology Data Exchange (ETDEWEB)

    Balsara, D.; Quinlan, D.J.

    1997-04-01

    In this paper we study adaptive mesh refinement (AMR) for elliptic and hyperbolic systems. We use the Asynchronous Fast Adaptive Composite Grid Method (AFACX), a parallel algorithm based upon the of Fast Adaptive Composite Grid Method (FAC) as a test case of an adaptive elliptic solver. For our hyperbolic system example we use TVD and ENO schemes for solving the Euler and MHD equations. We use the structured grid load balancer MLB as a tool for obtaining a load balanced distribution in a parallel environment. Parallel adaptive mesh refinement poses difficulties in expressing both the basic single grid solver, whether elliptic or hyperbolic, in a fashion that parallelizes seamlessly. It also requires that these basic solvers work together within the adaptive mesh refinement algorithm which uses the single grid solvers as one part of its adaptive solution process. We show that use of AMR++, an object-oriented library within the OVERTURE Framework, simplifies the development of AMR applications. Parallel support is provided and abstracted through the use of the P++ parallel array class.

  10. Mesh deployable antenna mechanics testing method

    Science.gov (United States)

    Jiang, Li

    Rapid development in spatial technologies and continuous expansion of astronautics applications require stricter and stricter standards in spatial structure. Deployable space structure as a newly invented structural form is being extensively adopted because of its characteristic (i.e. deployability). Deployable mesh reflector antenna is a kind of common deployable antennas. Its reflector consists in a kind of metal mesh. Its electrical properties are highly dependent on its mechanics parameters (including surface accuracy, angle, and position). Therefore, these mechanics parameters have to be calibrated. This paper presents a mesh antenna mechanics testing method that employs both an electronic theodolite and a laser tracker. The laser tracker is firstly used to measure the shape of radial rib deployable antenna. The measurement data are then fitted to a paraboloid by means of error compensation. Accordingly, the focus and the focal axis of the paraboloid are obtained. The following step is to synchronize the coordinate systems of the electronic theodolite and the measured antenna. Finally, in a microwave anechoic chamber environment, the electromechanical axis is calibrated. Testing results verify the effectiveness of the presented method.

  11. Journey from Mobile Ad Hoc Networks to Wireless Mesh Networks

    Science.gov (United States)

    Wang, Junfang; Xie, Bin; Agrawal, Dharma P.

    A wireless mesh network (WMN) is a particular type of mobile ad hoc network (MANET), which aims to provide ubiquitous high bandwidth access for a large number of users. A pure MANET is dynamically formed by mobile devices without the requirement of any existing infrastructure or prior network configuration. Similar to MANETs, a WMN also has the ability of self-organization, self-discovering, self-healing, and self-configuration. However, a WMN is typically a collection of stationary mesh routers (MRs) with each employing multiple radios. Some MRs have wired connections and act as the Internet gateways (IGWs) to provide Internet connectivity for other MRs. These new features of WMNs over MANETs enable them to be a promising alternative for high broadband Internet access. In this chapter, we elaborate on the evolution from MANETs to WMNs and provide a comprehensive understanding of WMNs from theoretical aspects to practical protocols, while comparing it with MANETs. In particular, we focus on the following critical issues with respect to WMN deployment: Network Capacity, Positioning Technique, Fairness Transmission and Multiradio Routing Protocols. We end this chapter with some open problems and future directions in WMNs.

  12. Data-Parallel Mesh Connected Components Labeling and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Cyrus; Childs, Hank; Gaither, Kelly

    2011-04-10

    We present a data-parallel algorithm for identifying and labeling the connected sub-meshes within a domain-decomposed 3D mesh. The identification task is challenging in a distributed-memory parallel setting because connectivity is transitive and the cells composing each sub-mesh may span many or all processors. Our algorithm employs a multi-stage application of the Union-find algorithm and a spatial partitioning scheme to efficiently merge information across processors and produce a global labeling of connected sub-meshes. Marking each vertex with its corresponding sub-mesh label allows us to isolate mesh features based on topology, enabling new analysis capabilities. We briefly discuss two specific applications of the algorithm and present results from a weak scaling study. We demonstrate the algorithm at concurrency levels up to 2197 cores and analyze meshes containing up to 68 billion cells.

  13. Data-Parallel Mesh Connected Components Labeling and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Cyrus; Childs, Hank; Gaither, Kelly

    2011-04-10

    We present a data-parallel algorithm for identifying and labeling the connected sub-meshes within a domain-decomposed 3D mesh. The identification task is challenging in a distributed-memory parallel setting because connectivity is transitive and the cells composing each sub-mesh may span many or all processors. Our algorithm employs a multi-stage application of the Union-find algorithm and a spatial partitioning scheme to efficiently merge information across processors and produce a global labeling of connected sub-meshes. Marking each vertex with its corresponding sub-mesh label allows us to isolate mesh features based on topology, enabling new analysis capabilities. We briefly discuss two specific applications of the algorithm and present results from a weak scaling study. We demonstrate the algorithm at concurrency levels up to 2197 cores and analyze meshes containing up to 68 billion cells.

  14. Oral, intestinal, and skin bacteria in ventral hernia mesh implants

    Directory of Open Access Journals (Sweden)

    Odd Langbach

    2016-07-01

    Full Text Available Background: In ventral hernia surgery, mesh implants are used to reduce recurrence. Infection after mesh implantation can be a problem and rates around 6–10% have been reported. Bacterial colonization of mesh implants in patients without clinical signs of infection has not been thoroughly investigated. Molecular techniques have proven effective in demonstrating bacterial diversity in various environments and are able to identify bacteria on a gene-specific level. Objective: The purpose of this study was to detect bacterial biofilm in mesh implants, analyze its bacterial diversity, and look for possible resemblance with bacterial biofilm from the periodontal pocket. Methods: Thirty patients referred to our hospital for recurrence after former ventral hernia mesh repair, were examined for periodontitis in advance of new surgical hernia repair. Oral examination included periapical radiographs, periodontal probing, and subgingival plaque collection. A piece of mesh (1×1 cm from the abdominal wall was harvested during the new surgical hernia repair and analyzed for bacteria by PCR and 16S rRNA gene sequencing. From patients with positive PCR mesh samples, subgingival plaque samples were analyzed with the same techniques. Results: A great variety of taxa were detected in 20 (66.7% mesh samples, including typical oral commensals and periodontopathogens, enterics, and skin bacteria. Mesh and periodontal bacteria were further analyzed for similarity in 16S rRNA gene sequences. In 17 sequences, the level of resemblance between mesh and subgingival bacterial colonization was 98–100% suggesting, but not proving, a transfer of oral bacteria to the mesh. Conclusion: The results show great bacterial diversity on mesh implants from the anterior abdominal wall including oral commensals and periodontopathogens. Mesh can be reached by bacteria in several ways including hematogenous spread from an oral site. However, other sites such as gut and skin may also

  15. Open Volumetric Mesh-An Efficient Data Structure for Tetrahedral and Hexa-hedral Meshes

    Institute of Scientific and Technical Information of China (English)

    XIAN Chu-hua; LI Gui-qing; GAO Shu-ming

    2013-01-01

    This work introduces a scalable and efficient topological structure for tetrahedral and hexahedral meshes. The design of the data structure aims at maximal flexibility and high performance. It provides a high scalability by using hierarchical representa-tions of topological elements. The proposed data structure is array-based, and it is a compact representation of the half-edge data structure for volume elements and half-face data structure for volumetric meshes. This guarantees constant access time to the neighbors of the topological elements. In addition, an open-source implementation named Open Volumetric Mesh (OVM) of the pro-posed data structure is written in C++using generic programming concepts.

  16. Computed tomographic measurements of mesh shrinkage after laparoscopic ventral incisional hernia repair with an expanded polytetrafluoroethylene mesh.

    Science.gov (United States)

    Schoenmaeckers, Ernst J P; van der Valk, Steef B A; van den Hout, Huib W; Raymakers, Johan F T J; Rakic, Srdjan

    2009-07-01

    The potential for shrinkage of intraperitoneally implanted meshes for laparoscopic repair of ventral and incisional hernia (LRVIH) remains a concern. Numerous experimental studies on this issue reported very inconsistent results. Expanded polytetrafluoroethylene (ePTFE) mesh has the unique property of being revealed by computed tomography (CT). We therefore conducted an analysis of CT findings in patients who had previously undergone LRVIH with an ePTFE mesh (DualMesh, WL Gore, Flagstaff, AZ, USA) in order to evaluate the shrinkage of implanted meshes. Of 656 LRVIH patients with DualMesh, all patients who subsequently underwent CT scanning were identified and only those with precisely known transverse diameter of implanted mesh and with CT scans made more than 3 months postoperatively were selected (n = 40). Two radiologists who were blinded to the size of the implanted mesh measured in consensus the maximal transverse diameter of the meshes by using the AquariusNET program (TeraRecon Inc., San Mateo, CA, USA). Mesh shrinkage was defined as the relative loss of transverse diameter as compared with the original transverse diameter of the mesh. The mean time from LRVIH to CT scan was 17.9 months (range 3-59 months). The mean shrinkage of the mesh was 7.5% (range 0-23.7%). For 11 patients (28%) there was no shrinkage at all. Shrinkage of 1-10% was found in 16 patients (40%), of 10-20% in 10 patients (25%), and of 20-24% in 3 patients (7.5%). No correlation was found regarding the elapsed time between LRVIH and CT, and shrinkage. There were two recurrences, one possibly related to shrinkage. Our observations indicate that shrinkage of DualMesh is remarkably lower than has been reported in experimental studies (8-51%). This study is the first to address the problem of shrinkage after intraperitoneal implantation of synthetic mesh in a clinical material.

  17. A comparative study of postoperative complications of lightweight mesh and conventional prolene mesh in Lichtenstein hernia repair

    Directory of Open Access Journals (Sweden)

    Gugri Mukthinath

    2016-06-01

    Full Text Available Background: Inguinal hernia repair is the most frequently performed operation in any general surgical unit. The complications of using the mesh has been the rationale to examine the role of mesh in hernia repair in detail and to begin investigating the biocompatibility of different mesh modifications and to challenge old mesh concepts. Therefore the present study is undertaken to compare the lightweight mesh (Ultrapro with conventional prolene mesh in lichtenstein hernia repair. Methods: Thirty one patients with primary unilateral inguinal hernia was subjected either to lightweight mesh Lichtenstein's hernioplasty or standard prolene mesh Lichtenstein's hernioplasty. The patients were followed in the surgical OPD at 1 month, 6 months and 1 year for time taken to return to normal activities, chronic groin pain, foreign body sensation, seroma formation and recurrence. Results: Chronic pain among patients in standard prolene mesh group at 1 month, 6 month, and 1 year follow up was seen in 45.2%, 16% and 3.2% of the patients respectively, in light weight mesh group patients at 1 month, 6 month and 1 year follow up was 32.2%, 6.4% and none at one year respectively. Foreign body sensation in the light weight mesh group is significantly less compared to patients in standard prolene mesh group. Time taken to return to work was relatively shorter among patients in Light weight mesh group. There was no recurrence in both groups. Conclusion: Light weight mesh is an ideal choice in Lichenstein's hernioplasty whenever feasible. [Int J Res Med Sci 2016; 4(6.000: 2130-2134

  18. A STUDY OF POSTOPERATIVE COMPLICATIONS FOLLOWING OPEN MESH INGUINAL HERNIA REPAIR

    Directory of Open Access Journals (Sweden)

    Abdul Kalam

    2016-09-01

    Full Text Available BACKGROUND Inguinal hernia is the most common type of hernia. Inguinal region consists of deep inguinal ring, inguinal canal and superficial inguinal ring, which make the region weak and susceptible to hernia. 65% of inguinal hernias are indirect hernias and 35% direct hernias. Hernioplasty is the strengthening of posterior wall of inguinal canal. It can be done either with the help of mesh repair or darning. Hernioplasty is indicated in recurrent hernia cases, inguinal hernia with weak abdominal muscle tone where mesh plasty is preferred and inguinal hernia with good muscle tone where darning can be done. In mesh repair, posterior wall (Lichtenstein repair of inguinal canal is strengthened by a Prolene or Marlex mesh. Over time, fibroblasts and capillaries grow over the mesh converting it into a thick sheath strengthening the posterior wall. Complications which can be encountered postsurgery are pain, bleeding, urinary retention, scrotal swelling, abdominal distension, seroma and wound infections, chronic pain, keloid and testicular atrophy. MATERIALS AND METHODS  The study was conducted in the Department of General Surgery, Travancore Medical College, Kollam.  The study was done from January 2015 to January 2016.  One hundred cases were identified and were chosen for the study. INCLUSION CRITERIA 1. Inguinal hernia cases treated by open mesh repair. EXCLUSION CRITERIA 1. Other types of inguinal hernia repair. RESULTS All the cases studied belonged to male sex. In our study, age group twenty to forty years amounted to sixty one cases followed by age group forty to sixty years, which amounted to twenty eight cases. Age group zero to twenty years amounted to six cases and age group more than sixty years amounted to five cases. In the study group, seventy two cases were indirect inguinal hernias and twenty eight cases were direct inguinal hernias. Based on the complications encountered, pain at the site was the commonest complaint, which

  19. A Collective Review on Mesh-Based Repair of Umbilical and Epigastric Hernias.

    Science.gov (United States)

    Ponten, Jeroen E H; Thomassen, Irene; Nienhuijs, Simon W

    2014-10-01

    In accordance with the tension-free principles for other hernias, umbilical and epigastric hernia repair should probably be mesh-based. The number of randomized studies is increasing, most of them showing significantly less recurrences with the use of a mesh. Different devices are available and are applicable by several approaches. The objective of this review was to evaluate recent literature for the different types of mesh for umbilical and epigastric hernia repair and recurrences after mesh repair. A multi-database search was conducted to reveal relevant studies since 2001 reporting mesh-based repair of primary umbilical/epigastric hernia and their outcomes in adult patients. A total of 20 studies were included, 15 of them solely involved umbilical hernias, whereas the remaining studies included epigastric hernias as well. A median of 124 patients (range, 17-384) was investigated per study. Three quarters of the included studies had a follow-up of at least 2 years. Six studies described the results of laparoscopic approach, of which one reported a recurrence rate of 2.7 %; in the remaining studies, no recurrences occurred. Two comparative studies reported a lower incidence of complications and postoperative pain after laparoscopic repair compared to open repair. Seventeen studies reported results of open techniques, of which seven studies showed no recurrence. Other studies reported recurrence rates up to 3.1 %. A wide range of complication rates were reported (0-33 %). This collective review showed acceptable recurrence rates for mesh-based umbilical and epigastric hernia repair. A wide range of devices was investigated. A tendency toward more complications after laparoscopic repair was found compared to open repair.

  20. Combining spray nozzle simulators with meshes: characterization of rainfall intensity and drop properties

    Science.gov (United States)

    Carvalho, Sílvia C. P.; de Lima, João L. M. P.; de Lima, M. Isabel P.

    2013-04-01

    Rainfall simulators can be a powerful tool to increase our understanding of hydrological and geomorphological processes. Nevertheless, rainfall simulators' design and operation might be rather demanding, for achieving specific rainfall intensity distributions and drop characteristics. The pressurized simulators have some advantages over the non-pressurized simulators: drops do not rely on gravity to reach terminal velocity, but are sprayed out under pressure; pressurized simulators also yield a broad range of drop sizes in comparison with drop-formers simulators. The main purpose of this study was to explore in the laboratory the potential of combining spray nozzle simulators with meshes in order to change rainfall characteristics (rainfall intensity and diameters and fall speed of drops). Different types of spray nozzles were tested, such as single full-cone and multiple full-cone nozzles. The impact of the meshes on the simulated rain was studied by testing different materials (i.e. plastic and steel meshes), square apertures and wire thicknesses, and different vertical distances between the nozzle and the meshes underneath. The diameter and fall speed of the rain drops were measured using a Laser Precipitation Monitor (Thies Clima). The rainfall intensity range and coefficients of uniformity of the sprays and the drop size distribution, fall speed and kinetic energy were analysed. Results show that when meshes intercept drop trajectories the spatial distribution of rainfall intensity and the drop size distribution are affected. As the spray nozzles generate typically small drop sizes and narrow drop size distributions, meshes can be used to promote the formation of bigger drops and random their landing positions.

  1. Unbiased sampling and meshing of isosurfaces

    KAUST Repository

    Yan, Dongming

    2014-11-01

    In this paper, we present a new technique to generate unbiased samples on isosurfaces. An isosurface, F(x,y,z) = c , of a function, F , is implicitly defined by trilinear interpolation of background grid points. The key idea of our approach is that of treating the isosurface within a grid cell as a graph (height) function in one of the three coordinate axis directions, restricted to where the slope is not too high, and integrating / sampling from each of these three. We use this unbiased sampling algorithm for applications in Monte Carlo integration, Poisson-disk sampling, and isosurface meshing.

  2. Perspective on the Lagrange-Jacobi mesh

    Science.gov (United States)

    Rampho, Gaotsiwe J.

    2016-07-01

    This paper presents a unified treatment of the kinetic energy matrix elements related to a number of Lagrange functions associated with the Lagrange-Jacobi mesh. The matrix elements can be readily modified for application to problems requiring eigenfunction expansion with Lagrange-Legendre, Lagrange-Chebyshev, Lagrange-Gegenbauer, as well as the Lagrange-Jacobi functions. The applicability of and the accuracy attainable with the matrix elements is demonstrated with the solution to the Schrödinger equation for confining trigonometric Pöschl-Teller potentials. The results obtained are within machine accuracy when appropriate choices of the basis functions are used.

  3. Performance of FACTS equipment in Meshed systems

    Energy Technology Data Exchange (ETDEWEB)

    Lerch, E.; Povh, D. [Siemens AG, Berlin (Germany)

    1994-12-31

    Modern power electronic devices such as thyristors and GTOs have made it possible to design controllable network elements, which will play a considerable role in ensuring reliable economic operation of transmission systems as a result of their capability to rapidly change active and reactive power. A number of FACTS elements for high-speed active and reactive power control will be described. Control of power system fluctuations in meshed systems by modulation of active and reactive power will be demonstrated using a number of examples. (author) 7 refs., 11 figs.

  4. Corset neophallic musculoplasty with a mesh endoprosthesis

    Directory of Open Access Journals (Sweden)

    V. V. Mikhailichenko

    2014-12-01

    Full Text Available During thoracodorsal flap phalloplasty, recovered contractility of the muscular base of the neophallus may lead to its shortening that impedes introjection.To eliminate deformity and shortening of the neophallus, the authors propose the procedure of corset plasty of its muscle, which differs in that the alloplastic material – esfil mesh endoprosthesis, is used as a corset instead of fascia latum of the hip. The proposed procedure reduces surgical trauma, improves the functional characteristics of the neophallus, and accelerates sexual rehabilitation.

  5. Corset neophallic musculoplasty with a mesh endoprosthesis

    Directory of Open Access Journals (Sweden)

    V. V. Mikhailichenko

    2014-01-01

    Full Text Available During thoracodorsal flap phalloplasty, recovered contractility of the muscular base of the neophallus may lead to its shortening that impedes introjection.To eliminate deformity and shortening of the neophallus, the authors propose the procedure of corset plasty of its muscle, which differs in that the alloplastic material – esfil mesh endoprosthesis, is used as a corset instead of fascia latum of the hip. The proposed procedure reduces surgical trauma, improves the functional characteristics of the neophallus, and accelerates sexual rehabilitation.

  6. Relativistic MHD with adaptive mesh refinement

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Matthew [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Hirschmann, Eric W [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States); Liebling, Steven L [Department of Physics, Long Island University-C W Post Campus, Brookville, NY 11548 (United States); Neilsen, David [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602 (United States)

    2006-11-22

    This paper presents a new computer code to solve the general relativistic magnetohydrodynamics (GRMHD) equations using distributed parallel adaptive mesh refinement (AMR). The fluid equations are solved using a finite difference convex ENO method (CENO) in 3 + 1 dimensions, and the AMR is Berger-Oliger. Hyperbolic divergence cleaning is used to control the {nabla} . B = 0 constraint. We present results from three flat space tests, and examine the accretion of a fluid onto a Schwarzschild black hole, reproducing the Michel solution. The AMR simulations substantially improve performance while reproducing the resolution equivalent unigrid simulation results. Finally, we discuss strong scaling results for parallel unigrid and AMR runs.

  7. Embedding meshes in Boolean cubes by graph decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C.T. (IBM Almaden Research Center, San Jose, CA (US)); Johnsson, S.L. (Dept. of Computer Science and Electrical Engineering, Yale Univ., New Haven, CT (US))

    1990-04-01

    This paper explores the embeddings of multidimensional meshes into minimal Boolean cubes by graph decomposition. The graph decomposition technique can be used to improve the average dilation and average congestion. The graph decomposition technique combined with some particular two-dimensional embeddings allows for minimal-expansion, dilation-two, congestion-two embeddings of about 87% of all two-dimensional meshes, with a significantly lower average dilation and congestion than by modified line compression. For three-dimensional meshes the authors show that the graph decomposition technique, together with two three-dimensional mesh embeddings presented in this paper and modified line compression, yields dilation-two embeddings of more than 96% of all three dimensional meshes contained in a 512 {times} 512 {times} 512 mesh.

  8. Image-Based Geometric Modeling and Mesh Generation

    CERN Document Server

    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,...

  9. HypGrid2D. A 2-d mesh generator

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, N.N.

    1998-03-01

    The implementation of a hyperbolic mesh generation procedure, based on an equation for orthogonality and an equation for the cell face area is described. The method is fast, robust and gives meshes with good smoothness and orthogonality. The procedure is implemented in a program called HypGrid2D. The HypGrid2D program is capable of generating C-, O- and `H`-meshes for use in connection with the EllipSys2D Navier-Stokes solver. To illustrate the capabilities of the program, some test examples are shown. First a series of C-meshes are generated around a NACA-0012 airfoil. Secondly a series of O-meshes are generated around a NACA-65-418 airfoil. Finally `H`-meshes are generated over a Gaussian hill and a linear escarpment. (au)

  10. MeSH key terms for validation and annotation of gene expression clusters

    Energy Technology Data Exchange (ETDEWEB)

    Rechtsteiner, A. (Andreas); Rocha, L. M. (Luis Mateus)

    2004-01-01

    Integration of different sources of information is a great challenge for the analysis of gene expression data, and for the field of Functional Genomics in general. As the availability of numerical data from high-throughput methods increases, so does the need for technologies that assist in the validation and evaluation of the biological significance of results extracted from these data. In mRNA assaying with microarrays, for example, numerical analysis often attempts to identify clusters of co-expressed genes. The important task to find the biological significance of the results and validate them has so far mostly fallen to the biological expert who had to perform this task manually. One of the most promising avenues to develop automated and integrative technology for such tasks lies in the application of modern Information Retrieval (IR) and Knowledge Management (KM) algorithms to databases with biomedical publications and data. Examples of databases available for the field are bibliographic databases c ntaining scientific publications (e.g. MEDLINE/PUBMED), databases containing sequence data (e.g. GenBank) and databases of semantic annotations (e.g. the Gene Ontology Consortium and Medical Subject Headings (MeSH)). We present here an approach that uses the MeSH terms and their concept hierarchies to validate and obtain functional information for gene expression clusters. The controlled and hierarchical MeSH vocabulary is used by the National Library of Medicine (NLM) to index all the articles cited in MEDLINE. Such indexing with a controlled vocabulary eliminates some of the ambiguity due to polysemy (terms that have multiple meanings) and synonymy (multiple terms have similar meaning) that would be encountered if terms would be extracted directly from the articles due to differing article contexts or author preferences and background. Further, the hierarchical organization of the MeSH terms can illustrate the conceptuallfunctional relationships of genes

  11. Dynamic Mesh Adaptation for Front Evolution Using Discontinuous Galerkin Based Weighted Condition Number Mesh Relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, Patrick T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schofield, Samuel P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nourgaliev, Robert [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-06-21

    A new mesh smoothing method designed to cluster mesh cells near a dynamically evolving interface is presented. The method is based on weighted condition number mesh relaxation with the weight function being computed from a level set representation of the interface. The weight function is expressed as a Taylor series based discontinuous Galerkin projection, which makes the computation of the derivatives of the weight function needed during the condition number optimization process a trivial matter. For cases when a level set is not available, a fast method for generating a low-order level set from discrete cell-centered elds, such as a volume fraction or index function, is provided. Results show that the low-order level set works equally well for the weight function as the actual level set. Meshes generated for a number of interface geometries are presented, including cases with multiple level sets. Dynamic cases for moving interfaces are presented to demonstrate the method's potential usefulness to arbitrary Lagrangian Eulerian (ALE) methods.

  12. MeSH Up: effective MeSH text classification for improved document retrieval

    NARCIS (Netherlands)

    Trieschnigg, Dolf; Pezik, Piotr; Lee, Vivian; Jong, de Franciska; Kraaij, Wessel; Rebholz-Schuhmann, Dietrich

    2009-01-01

    Motivation: Controlled vocabularies such as the Medical Subject Headings (MeSH) thesaurus and the Gene Ontology (GO) provide an efficient way of accessing and organizing biomedical information by reducing the ambiguity inherent to free-text data. Different methods of automating the assignment of MeS

  13. MeSH Up: Effective MeSH text classification for improved document retrieval

    NARCIS (Netherlands)

    Trieschnigg, D.; Pezik, P.; Lee, V.; Jong, F.de; Kraaij, W.; Rebholz-Schuhmann, D.

    2009-01-01

    Motivation: Controlled vocabularies such as the Medical Subject Headings (MeSH) thesaurus and the Gene Ontology (GO) provide an efficient way of accessing and organizing biomedical information by reducing the ambiguity inherent to free-text data. Different methods of automating the assignment of MeS

  14. AUTOMATIC MESH GENERATION OF 3-D GEOMETRIC MODELS

    Institute of Scientific and Technical Information of China (English)

    刘剑飞

    2003-01-01

    In this paper the presentation of the ball-packing method is reviewed,and a scheme to generate mesh for complex 3-D geometric models is given,which consists of 4 steps:(1)create nodes in 3-D models by ball-packing method,(2)connect nodes to generate mesh by 3-D Delaunay triangulation,(3)retrieve the boundary of the model after Delaunay triangulation,(4)improve the mesh.

  15. Vertex-based diffusion for 3-D mesh denoising.

    Science.gov (United States)

    Zhang, Ying; Ben Hamza, A

    2007-04-01

    We present a vertex-based diffusion for 3-D mesh denoising by solving a nonlinear discrete partial differential equation. The core idea behind our proposed technique is to use geometric insight in helping construct an efficient and fast 3-D mesh smoothing strategy to fully preserve the geometric structure of the data. Illustrating experimental results demonstrate a much improved performance of the proposed approach in comparison with existing methods currently used in 3-D mesh smoothing.

  16. Multiphase Flow of Immiscible Fluids on Unstructured Moving Meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam;

    2013-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization op...... complement and solve our optimization on the GPU. We provide the results of parameter studies as well as a performance analysis of our method, together with suggestions for performance optimization....

  17. Automated quadrilateral mesh generation for digital image structures

    Institute of Scientific and Technical Information of China (English)

    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...

  18. Hexahedral mesh generation via the dual arrangement of surfaces

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. A moving mesh finite difference method for non-monotone solutions of non-equilibrium equations in porous media

    CERN Document Server

    Zhang, Hong

    2016-01-01

    An adaptive moving mesh finite difference method is presented to solve two types of equations with dynamic capillary pressure term in porous media. One is the non-equilibrium Richards Equation and the other is the modified Buckley-Leverett equation. The governing equations are discretized with an adaptive moving mesh finite difference method in the space direction and an implicit-explicit method in the time direction. In order to obtain high quality meshes, an adaptive time-dependent monitor function with directional control is applied to redistribute the mesh grid in every time step, and a diffusive mechanism is used to smooth the monitor function. The behaviors of the central difference flux, the standard local Lax-Friedrich flux and the local Lax-Friedrich flux with reconstruction are investigated by solving a 1D modified Buckley-Leverett equation. With the moving mesh technique, good mesh quality and high numerical accuracy are obtained. A collection of one-dimensional and two-dimensional numerical experi...

  20. Finding Regions of Interest on Toroidal Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kesheng; Sinha, Rishi R; Jones, Chad; Ethier, Stephane; Klasky, Scott; Ma, Kwan-Liu; Shoshani, Arie; Winslett, Marianne

    2011-02-09

    Fusion promises to provide clean and safe energy, and a considerable amount of research effort is underway to turn this aspiration intoreality. This work focuses on a building block for analyzing data produced from the simulation of microturbulence in magnetic confinementfusion devices: the task of efficiently extracting regions of interest. Like many other simulations where a large amount of data are produced,the careful study of ``interesting'' parts of the data is critical to gain understanding. In this paper, we present an efficient approach forfinding these regions of interest. Our approach takes full advantage of the underlying mesh structure in magnetic coordinates to produce acompact representation of the mesh points inside the regions and an efficient connected component labeling algorithm for constructingregions from points. This approach scales linearly with the surface area of the regions of interest instead of the volume as shown with bothcomputational complexity analysis and experimental measurements. Furthermore, this new approach is 100s of times faster than a recentlypublished method based on Cartesian coordinates.

  1. GRChombo : Numerical Relativity with Adaptive Mesh Refinement

    CERN Document Server

    Clough, Katy; Finkel, Hal; Kunesch, Markus; Lim, Eugene A; Tunyasuvunakool, Saran

    2015-01-01

    Numerical relativity has undergone a revolution in the past decade. With a well-understood mathematical formalism, and full control over the gauge modes, it is now entering an era in which the science can be properly explored. In this work, we introduce GRChombo, a new numerical relativity code written to take full advantage of modern parallel computing techniques. GRChombo's features include full adaptive mesh refinement with block structured Berger-Rigoutsos grid generation which supports non-trivial "many-boxes-in-many-boxes" meshing hierarchies, and massive parallelism through the Message Passing Interface (MPI). GRChombo evolves the Einstein equation with the standard BSSN formalism, with an option to turn on CCZ4 constraint damping if required. We show that GRChombo passes all the standard "Apples-to-Apples" code comparison tests. We also show that it can stably and accurately evolve vacuum black hole spacetimes such as binary black hole mergers, and non-vacuum spacetimes such as scalar collapses into b...

  2. The Tera Multithreaded Architecture and Unstructured Meshes

    Science.gov (United States)

    Bokhari, Shahid H.; Mavriplis, Dimitri J.

    1998-01-01

    The Tera Multithreaded Architecture (MTA) is a new parallel supercomputer currently being installed at San Diego Supercomputing Center (SDSC). This machine has an architecture quite different from contemporary parallel machines. The computational processor is a custom design and the machine uses hardware to support very fine grained multithreading. The main memory is shared, hardware randomized and flat. These features make the machine highly suited to the execution of unstructured mesh problems, which are difficult to parallelize on other architectures. We report the results of a study carried out during July-August 1998 to evaluate the execution of EUL3D, a code that solves the Euler equations on an unstructured mesh, on the 2 processor Tera MTA at SDSC. Our investigation shows that parallelization of an unstructured code is extremely easy on the Tera. We were able to get an existing parallel code (designed for a shared memory machine), running on the Tera by changing only the compiler directives. Furthermore, a serial version of this code was compiled to run in parallel on the Tera by judicious use of directives to invoke the "full/empty" tag bits of the machine to obtain synchronization. This version achieves 212 and 406 Mflop/s on one and two processors respectively, and requires no attention to partitioning or placement of data issues that would be of paramount importance in other parallel architectures.

  3. Mesh-based parallel code coupling interface

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, K.; Steckel, B. (eds.) [GMD - Forschungszentrum Informationstechnik GmbH, St. Augustin (DE). Inst. fuer Algorithmen und Wissenschaftliches Rechnen (SCAI)

    2001-04-01

    MpCCI (mesh-based parallel code coupling interface) is an interface for multidisciplinary simulations. It provides industrial end-users as well as commercial code-owners with the facility to combine different simulation tools in one environment. Thereby new solutions for multidisciplinary problems will be created. This opens new application dimensions for existent simulation tools. This Book of Abstracts gives a short overview about ongoing activities in industry and research - all presented at the 2{sup nd} MpCCI User Forum in February 2001 at GMD Sankt Augustin. (orig.) [German] MpCCI (mesh-based parallel code coupling interface) definiert eine Schnittstelle fuer multidisziplinaere Simulationsanwendungen. Sowohl industriellen Anwender als auch kommerziellen Softwarehersteller wird mit MpCCI die Moeglichkeit gegeben, Simulationswerkzeuge unterschiedlicher Disziplinen miteinander zu koppeln. Dadurch entstehen neue Loesungen fuer multidisziplinaere Problemstellungen und fuer etablierte Simulationswerkzeuge ergeben sich neue Anwendungsfelder. Dieses Book of Abstracts bietet einen Ueberblick ueber zur Zeit laufende Arbeiten in der Industrie und in der Forschung, praesentiert auf dem 2{sup nd} MpCCI User Forum im Februar 2001 an der GMD Sankt Augustin. (orig.)

  4. Feature detection of triangular meshes vianeighbor supporting

    Institute of Scientific and Technical Information of China (English)

    Xiao-chao WANG; Jun-jie CAO; Xiu-ping LIU; Bao-jun LI; Xi-quan SHI; Yi-zhen SUN

    2012-01-01

    We propose a robust method for detecting features on triangular meshes by combining normal tensor voting with neighbor supporting.Our method contains two stages:feature detection and feature refinement.First,the normal tensor voting method is modified to detect the initial features,which may include some pseudo features.Then,at the feature refinement stage,a novel salient measure deriving from the idea of neighbor supporting is developed. Benefiting from the integrated reliable salient measure feature,pseudo features can be effectively discriminated from the initially detected features and removed. Compared to previous methods based on the differential geometric property,the main advantage of our method is that it can detect both sharp and weak features.Numerical experiments show that our algorithm is robust,effective,and can produce more accurate results.We also discuss how detected features are incorporated into applications,such as feature-preserving mesh denoising and hole-filling,and present visually appealing results by integrating feature information.

  5. An Evaluation Method for Distortion Energy Parameterization of Triangular Meshes

    Institute of Scientific and Technical Information of China (English)

    SHI Jing; ZHAO Xiu-yang; ZHANG Cai-ming; YANG Bo

    2013-01-01

    Parameterization of triangle meshes is a fundamental problem for texture mapping, surface fitting, surface reconstruction, and mesh editing. The deformation of triangular meshes caused by the parameterized process is the measurement of parameterization. Traditional standard method has its limitation when evaluating mixture distortion energy parameterizations. Thus an evaluation method bases on distortion energy parameterization of triangular meshes is introduced for the limitation. The novel method employs an adaptive expression form to the mixture energy, and uses a weight factor to represent distortion energy distribution. By using this method, we can evaluate all kinds of parameterization in a uniform measurement and acquire a more intuitive and clear evaluation.

  6. Numerical modeling of seismic waves using frequency-adaptive meshes

    Science.gov (United States)

    Hu, Jinyin; Jia, Xiaofeng

    2016-08-01

    An improved modeling algorithm using frequency-adaptive meshes is applied to meet the computational requirements of all seismic frequency components. It automatically adopts coarse meshes for low-frequency computations and fine meshes for high-frequency computations. The grid intervals are adaptively calculated based on a smooth inversely proportional function of grid size with respect to the frequency. In regular grid-based methods, the uniform mesh or non-uniform mesh is used for frequency-domain wave propagators and it is fixed for all frequencies. A too coarse mesh results in inaccurate high-frequency wavefields and unacceptable numerical dispersion; on the other hand, an overly fine mesh may cause storage and computational overburdens as well as invalid propagation angles of low-frequency wavefields. Experiments on the Padé generalized screen propagator indicate that the Adaptive mesh effectively solves these drawbacks of regular fixed-mesh methods, thus accurately computing the wavefield and its propagation angle in a wide frequency band. Several synthetic examples also demonstrate its feasibility for seismic modeling and migration.

  7. Dimensionality Reduction of Laplacian Embedding for 3D Mesh Reconstruction

    Science.gov (United States)

    Mardhiyah, I.; Madenda, S.; Salim, R. A.; Wiryana, I. M.

    2016-06-01

    Laplacian eigenbases are the important thing that we have to process from 3D mesh information. The information of geometric 3D mesh are include vertices locations and the connectivity of graph. Due to spectral analysis, geometric 3D mesh for large and sparse graphs with thousands of vertices is not practical to compute all the eigenvalues and eigenvector. Because of that, in this paper we discuss how to build 3D mesh reconstruction by reducing dimensionality on null eigenvalue but retain the corresponding eigenvector of Laplacian Embedding to simplify mesh processing. The result of reducing information should have to retained the connectivity of graph. The advantages of dimensionality reduction is for computational eficiency and problem simplification. Laplacian eigenbases is the point of dimensionality reduction for 3D mesh reconstruction. In this paper, we show how to reconstruct geometric 3D mesh after approximation step of 3D mesh by dimensionality reduction. Dimensionality reduction shown by Laplacian Embedding matrix. Furthermore, the effectiveness of 3D mesh reconstruction method will evaluated by geometric error, differential error, and final error. Numerical approximation error of our result are small and low complexity of computational.

  8. A New Approach to Fully Automatic Mesh Generation

    Institute of Scientific and Technical Information of China (English)

    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.

  9. Biology of biological meshes used in hernia repair.

    Science.gov (United States)

    Novitsky, Yuri W

    2013-10-01

    Successful repair of most hernias requires the use of a prosthetic implant for reinforcement of the defect. Because of the need for prosthetic implants to resist infections as well to support repairs in contaminated or potentially contaminated fields, biological meshes have been developed to take the place of nondegradable synthetic meshes in cases where mesh infection is of high concern. The ideal is a biological matrix that resists infection while providing durable reinforcement of a hernia repair. This article reviews the validity of assumptions that support the purported notion of the biological behavior of biological meshes.

  10. Multicentric observational study of pain after the use of a self-gripping lightweight mesh.

    Science.gov (United States)

    García Ureña, M Á; Hidalgo, M; Feliu, X; Velasco, M Á; Revuelta, S; Gutiérrez, R; Utrera, A; Porrero, J L; Marín, M; Zaragoza, C

    2011-10-01

    Investigation in the field of inguinal hernia surgery is now focused on postoperative pain. The extended use of lightweight meshes and alternative methods of fixation may play a relevant role in the reduction of pain. In this study, a new self-gripping lightweight polypropylene mesh is tested. A multicentric, observational study was scheduled to prospectively evaluate this new mesh. Ten centers agreed to participate. Only primary, type 1 or 2 uncomplicated hernias in adults were included. The mesh was placed as a Lichtenstein procedure without any fixation. A complete pain questionnaire was followed at 1 week, and at 1, 3 and 6 months postoperatively. The principal goal of the study was to evaluate maximum pain score at 6 months. Pain was assessed by a visual analog scale. A total of 256 patients were operated. Mean operative time was 35.6 min; 76.2% of patients were operated in an ambulatory setting. There were a few postoperative complications: 2 wound infections, 17 seromas, 21 hematomas, 6 orchitis. The incidence of acute pain was 27.3% at week 1 and 7.5% at month 1. The incidence of chronic pain was 3.6% at month 3 and 2.8% at month 6. No recurrences or long-term complications were observed. This self-gripping mesh can be used safely in type 1 and 2 primary, uncomplicated inguinal hernia with minimal morbidity and most patients under ambulatory setting. The registered incidence of chronic pain is lower than 3%.

  11. Complications of grafts used in female pelvic floor reconstruction: Mesh erosion and extrusion

    Directory of Open Access Journals (Sweden)

    Tanya M Nazemi

    2007-01-01

    Full Text Available Introduction: Various grafts have been used in the treatment of urinary incontinence and pelvic prolapse. Autologous materials such as muscle and fascia were first utilized to provide additional anatomic support to the periurethral and pelvic tissues; however, attempts to minimize the invasiveness of the procedures have led to the use of synthetic materials. Complications such as infection and erosion or extrusion associated with these materials may be troublesome to manage. We review the literature and describe a brief overview of grafts used in pelvic floor reconstruction and focus on the management complications specifically related to synthetic materials. Materials and Methods: We performed a comprehensive review of the literature on grafts used in pelvic floor surgery using MEDLINE and resources cited in those peer-reviewed manuscripts. The results are presented. Results: Biologic materials provide adequate cure rates but have associated downfalls including potential complications from harvesting, variable tissue quality and cost. The use of synthetic materials as an alternative graft in pelvic floor repairs has become a popular option. Of all synthetic materials, the type I macroporous polypropylene meshes have demonstrated superiority in terms of efficacy and fewer complication rates due to their structure and composition. Erosion and extrusion of mesh are common and troublesome complications that may be managed conservatively with observation with or without local hormone therapy, with transvaginal debridement or with surgical exploration and total mesh excision, dependent upon the location of the mesh and the mesh type utilized. Conclusions: The ideal graft would provide structural integrity and durability with minimal adverse reaction by the host tissue. Biologic materials in general tend to have fewer associated complications, however, the risks of harvesting, variable integrity of allografts, availability and high cost has led to the

  12. MeshVoro: A Three-Dimensional Voronoi Mesh Building Tool for the TOUGH Family of Codes

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, C. M.; Boyle, K. L.; Reagan, M.; Johnson, J.; Rycroft, C.; Moridis, G. J.

    2013-09-30

    Few tools exist for creating and visualizing complex three-dimensional simulation meshes, and these have limitations that restrict their application to particular geometries and circumstances. Mesh generation needs to trend toward ever more general applications. To that end, we have developed MeshVoro, a tool that is based on the Voro (Rycroft 2009) library and is capable of generating complex threedimensional Voronoi tessellation-based (unstructured) meshes for the solution of problems of flow and transport in subsurface geologic media that are addressed by the TOUGH (Pruess et al. 1999) family of codes. MeshVoro, which includes built-in data visualization routines, is a particularly useful tool because it extends the applicability of the TOUGH family of codes by enabling the scientifically robust and relatively easy discretization of systems with challenging 3D geometries. We describe several applications of MeshVoro. We illustrate the ability of the tool to straightforwardly transform a complex geological grid into a simulation mesh that conforms to the specifications of the TOUGH family of codes. We demonstrate how MeshVoro can describe complex system geometries with a relatively small number of grid blocks, and we construct meshes for geometries that would have been practically intractable with a standard Cartesian grid approach. We also discuss the limitations and appropriate applications of this new technology.

  13. Infection susceptibility of crosslinked and non-crosslinked biological meshes in an experimental contaminated environment.

    Science.gov (United States)

    Mulder, Irene M; Deerenberg, Eva B; Bemelman, Willem A; Jeekel, Johannes; Lange, Johan F

    2015-07-01

    This experimental study investigates infectious complications and functional outcome of biological meshes in a contaminated environment. In 90 rats peritonitis was induced, and after 24 hours, a biological mesh was implanted intraperitoneally including 2 non-crosslinked mesh groups (Strattice and Surgisis) and 2 crosslinked mesh groups (CollaMendFM and Permacol). Sacrifice was after 90 and 180 days. More mesh infections occurred in crosslinked meshes compared with non-crosslinked meshes (70% vs 4%; P contaminated field was the highest in crosslinked meshes. All biological meshes showed poor incorporation, which makes long-term abdominal wall repair questionable. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. [Laparoscopic inguinal hernia repair "IPOM" with Dual-Mesh].

    Science.gov (United States)

    Catani, M; De Milito, R; Materia, A; Chiaretti, M; Spaziani, E; Manili, G; Simi, M

    2003-01-01

    The authors report their experience on laparoscopic hernioplasty using the Intraperitoneal Onlay Mesh Repair (IPOM) in 56 patients. 34 patients had a bilateral hernia, 6 of which were recurrent and 22 had a monolateral hernia, of which 9 had recurrent hernia. Overall, a total of 90 hernias were treated. The hernia repair was performed utilizing "GORE-TEX DualMesh Plus biomaterial with holes" in the first 32 cases and the latest "...Corduroy" type in the remaining 24 cases. The prostheses were fixed with titanium spiral tacks (Protack, AutoSuture, Tyco Healthcare). No intraoperative complications occurred and no conversion was necessary. Five minor post-operative complications (5.5%), 2 seromas and 3 transient paresthesias, were observed. Four patients (7.1%) needed analgesics after the first 24 hours. Mean hospital stay was 36 hours, with a minimum of 24 and a maximum of 48. Mean resumption of normal activity was 8 days with return to work within two weeks. At an average 18 months follow-up, 3 recurrences were recorded (3.3%). The results of this study as well as the meta-analysis of the series presented in the Literature, indicate that the IPOM may be a feasible, safe and effective procedure in the treatment of recurrent and bilateral hernias or when a hernia repair is performed during other laparoscopic procedures. The IPOM has infact been shown to be faster and easier than the other more commonly performed laparoscopic hernioplasties (TAPP and TEP). These data may also suggest to utilize this technique in particular cases of primitive hernia such as very active young males or heavy duty workers. However the limited series and the short follow-up ask for randomized prospective long term studies to definitely ascertain the true incidence of recurrence and therefore the effectiveness of this attractive procedure.

  15. Nonhydrostatic adaptive mesh dynamics for multiscale climate models (Invited)

    Science.gov (United States)

    Collins, W.; Johansen, H.; McCorquodale, P.; Colella, P.; Ullrich, P. A.

    2013-12-01

    Many of the atmospheric phenomena with the greatest potential impact in future warmer climates are inherently multiscale. Such meteorological systems include hurricanes and tropical cyclones, atmospheric rivers, and other types of hydrometeorological extremes. These phenomena are challenging to simulate in conventional climate models due to the relatively coarse uniform model resolutions relative to the native nonhydrostatic scales of the phenomonological dynamics. To enable studies of these systems with sufficient local resolution for the multiscale dynamics yet with sufficient speed for climate-change studies, we have adapted existing adaptive mesh dynamics for the DOE-NSF Community Atmosphere Model (CAM). In this talk, we present an adaptive, conservative finite volume approach for moist non-hydrostatic atmospheric dynamics. The approach is based on the compressible Euler equations on 3D thin spherical shells, where the radial direction is treated implicitly (using a fourth-order Runga-Kutta IMEX scheme) to eliminate time step constraints from vertical acoustic waves. Refinement is performed only in the horizontal directions. The spatial discretization is the equiangular cubed-sphere mapping, with a fourth-order accurate discretization to compute flux averages on faces. By using both space-and time-adaptive mesh refinement, the solver allocates computational effort only where greater accuracy is needed. The resulting method is demonstrated to be fourth-order accurate for model problems, and robust at solution discontinuities and stable for large aspect ratios. We present comparisons using a simplified physics package for dycore comparisons of moist physics. Hadley cell lifting an advected tracer into upper atmosphere, with horizontal adaptivity

  16. Analysis and Improvement of Upwind and Centered Schemes on Quadrilateral and Triangular Meshes

    Science.gov (United States)

    Huynh, H. T.

    2003-01-01

    Second-order accurate upwind and centered schemes are presented in a framework that facilitates their analysis and comparison. The upwind scheme employed consists of a reconstruction step (MUSCL approach) followed by an upwind step (Roe's flux-difference splitting). The two centered schemes are of Lax-Friedrichs (L-F) type. They are the nonstaggered versions of the Nessyahu-Tadmor (N-T) scheme and the CE/SE method with epilson = 1/2. The upwind scheme is extended to the case of two spatial dimensions (2D) in a straightforward manner. The N-T and CE/SE schemes are extended in a manner similar to the 2D extensions of the CE/SE scheme by Wang and Chang for a triangular mesh and by Zhang, Yu, and Chang for a quadrilateral mesh. The slope estimates, however, are simplified. Fourier stability and accuracy analyses are carried out for these schemes for the standard 1D and the 2D quadrilateral mesh cases. In the nonstandard case of a triangular mesh, the triangles must be paired up when analyzing the upwind and N-T schemes. An observation resulting in an extended N-T scheme which is faster and uses only one-third of the storage for flow data compared with the CE/SE method is presented. Numerical results are shown. Other improvements to the schemes are discussed.

  17. RGB Technique of Intrusion Detection in IEEE 802.11 Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    M Salman Ashraf

    2012-03-01

    Full Text Available According to the growth rate of wireless technology, wireless mesh network (WMN usage is significantly increased according to its advantages like inexpensive, fast and easy deployment. WMN have ability, easy to create mesh and provide internet access in a cost efficient manner in any type of area which is unable or costly for wire mediums. Security attacks ratio is higher in wireless mesh network (WMN rather than other wireless or wire technologies. Spy /Malware infected computers generate malicious traffic, which uses valuable network resources and puts other systems at risk. Intrusion detection system (IDS is one of the possible solutions which timely detect the intrusions and alarm for appropriate action. But Limitation of many IDS of WMN are not timely response or unable to share with all nodes due its dynamic network topology and easy access to the radio medium. In this paper, proposed framework is timely detect intrusion and in response to share with all, in both standalone and cooperative manner. This paper also provides the basic sharing mechanism of intrusion for large scale bandwidth wireless mesh networks.

  18. Mesh patterns and the expansion of permutation statistics as sums of permutation patterns

    CERN Document Server

    Brändén, Petter

    2011-01-01

    Any permutation statistic $f:\\sym\\to\\CC$ may be represented uniquely as a, possibly infinite, linear combination of (classical) permutation patterns: $f= \\Sigma_\\tau\\lambda_f(\\tau)\\tau$. To provide explicit expansions for certain statistics, we introduce a new type of permutation patterns that we call mesh patterns. Intuitively, a mesh pattern $p=(\\pi,R)$ counts occurrences of the permutation pattern $\\pi$ with additional restrictions specified by $R$ on the relative position of the entries of the occurrence. We show that, for any mesh pattern $p=(\\pi,R)$, we have $\\lambda_p(\\tau) = (-1)^{|\\tau|-|\\pi|}p^{\\star}(\\tau)$ where $p^{\\star}=(\\pi,R^c)$ is the mesh pattern with the same underlying permutation as $p$ but with complementary restrictions. We use this result to expand some well known permutation statistics, such as the number of left-to-right maxima, descents, excedances, fixed points, strong fixed points, and the major index. We also show that alternating permutations, Andr\\'e permutations of the first ...

  19. An Internal Audit of Diabetes Care for Type 2 Diabetic Patients in a Public Hospital Diabetes Clinic in Malaysia.

    Science.gov (United States)

    Hieng, Yung Chun

    2017-03-01

    Earlier studies have identified a gap between guidelines and actual clinical diabetes care in Malaysia. We audited the quality of care for patients with type 2 diabetes mellitus (T2DM) attending our diabetes clinic at a public hospital. A structured review of the outpatient clinic cards, prescriptions and laboratory results was conducted for patients attending the diabetes clinic at Sibu Hospital in October and November 2014. For the total of 233 patients who were audited, the levels of fasting blood sugar, blood pressure, body mass index and fasting lipid profile were satisfactory at 99.1%, 99.6%, 92.6% and 99.6% respectively. 79.7% of the subjects had had HbA1c performed at least once over the previous six months. Only 25.8% had annual foot screening, while the eye screening rate was 71.2% and the albuminuria screening rate was 93.6%. For outcome measures, the mean (SD) HbA1c level was 9.2% (1.91%), with 13 patients (6.7%) having HbA1c less than 6.5%; 36.4% of participants achieved BP < 130/80 mmHg; and 69.4% had LDL < 2.6 mmol/L. The majority of the patients were overweight or obese (91.4%). Overall, the performance of diabetic care processes at our hospital was satisfactory, except for foot examination. The glycaemic and weight control among the subjects were suboptimal and warrant an optimised and comprehensive approach on the part of the management.

  20. A comparison of outcomes and cost in VHWG grade II hernias between Rives-Stoppa synthetic mesh hernia repair versus underlay biologic mesh repair.

    Science.gov (United States)

    Fischer, J P; Basta, M N; Mirzabeigi, M N; Kovach, S J

    2014-01-01

    The current literature is void of evidence-based guidelines regarding optimal choice of mesh. We aim to perform a comparative outcome analysis of synthetic mesh and acellular dermal matrix (ADM) in Ventral Hernia Working Grade (VHWG) grade II hernias with primary fascial closure. A retrospective review of patients undergoing ventral hernia repair (VHR) by the senior author (S.J.K.) from 2007 to 2012 was performed. Patients undergoing VHR with primary fascial closure were risk stratified using the VHWG defined grading system. Seventy-two patients met the abovementioned inclusion criteria with 45 receiving synthetic mesh and 27 receiving ADM. The mean length of follow-up was 12.1 ± 9.1 months. Patients were, on average, 53.2 ± 11.6 years of age with a BMI of 33.9 ± 10.6 kg/m(2). The overall incidence of surgical site occurrence (SSO) in the cohort was 41.7 % and the incidence of hernia recurrence was 5.6 %. 30-day mortality was 1.2 %. Bivariate analysis demonstrated that obesity (P = 0.038) and number of comorbidities (P = 0.043) were associated with SSO. Bivariate analysis demonstrated that prior failed hernia, use of ADM, and operative time were associated with higher rates of hernia recurrence; however, adjusted multivariate regression found only prior failed hernia (OR = 4.1, P = 0.03) and biologic mesh (OR = 3.4, P = 0.046) to be independently associated with recurrent hernia. Comparison of mesh types revealed few differences in preoperative or operative characteristics between synthetic mesh and acellular dermal matrices (ADM). The rate of hernia recurrence was significantly higher with ADM (14.8 % vs. 0.0 %, P = 0.017). Patients receiving ADM repairs incurred significantly greater cost ($56,142.1 ± 54,775.5 vs. $30,599.8 ± 39,000.8, P hernia recurrences and lower cost utilization at 1-year. Prognostic/risk category, level III.

  1. Adaptive Mesh Refinement for Characteristic Grids

    CERN Document Server

    Thornburg, Jonathan

    2009-01-01

    I consider techniques for Berger-Oliger adaptive mesh refinement (AMR) when numerically solving partial differential equations with wave-like solutions, using characteristic (double-null) grids. Such AMR algorithms are naturally recursive, and the best-known past Berger-Oliger characteristic AMR algorithm, that of Pretorius & Lehner (J. Comp. Phys. 198 (2004), 10), recurses on individual "diamond" characteristic grid cells. This leads to the use of fine-grained memory management, with individual grid cells kept in 2-dimensional linked lists at each refinement level. This complicates the implementation and adds overhead in both space and time. Here I describe a Berger-Oliger characteristic AMR algorithm which instead recurses on null \\emph{slices}. This algorithm is very similar to the usual Cauchy Berger-Oliger algorithm, and uses relatively coarse-grained memory management, allowing entire null slices to be stored stored in contiguous arrays in memory. The algorithm is very efficient in both space and ti...

  2. Finite element differential forms on cubical meshes

    CERN Document Server

    Arnold, Douglas N

    2012-01-01

    We develop a family of finite element spaces of differential forms defined on cubical meshes in any number of dimensions. The family contains elements of all polynomial degrees and all form degrees. In two dimensions, these include the serendipity finite elements and the rectangular BDM elements. In three dimensions they include a recent generalization of the serendipity spaces, and new H(curl) and H(div) finite element spaces. Spaces in the family can be combined to give finite element subcomplexes of the de Rham complex which satisfy the basic hypotheses of the finite element exterior calculus, and hence can be used for stable discretization of a variety of problems. The construction and properties of the spaces are established in a uniform manner using finite element exterior calculus.

  3. Implicit compressible flow solvers on unstructured meshes

    Science.gov (United States)

    Nagaoka, Makoto; Horinouchi, Nariaki

    1993-09-01

    An implicit solver for compressible flows using Bi-CGSTAB method is proposed. The Euler equations are discretized with the delta-form by the finite volume method on the cell-centered triangular unstructured meshes. The numerical flux is calculated by Roe's upwind scheme. The linearized simultaneous equations with the irregular nonsymmetric sparse matrix are solved by the Bi-CGSTAB method with the preconditioner of incomplete LU factorization. This method is also vectorized by the multi-colored ordering. Although the solver requires more computational memory, it shows faster and more robust convergence than the other conventional methods: three-stage Runge-Kutta method, point Gauss-Seidel method, and Jacobi method for two-dimensional inviscid steady flows.

  4. Moving Mesh Cosmology: Properties of Gas Disks

    CERN Document Server

    Torrey, Paul; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2011-01-01

    We compare the structural properties of galaxies formed in cosmological simulations using the smoothed particle hydrodynamics (SPH) code GADGET with those using the moving-mesh code AREPO. Both codes employ identical gravity solvers and the same sub-resolution physics but use very different methods to track the hydrodynamic evolution of gas. This permits us to isolate the effects of the hydro solver on the formation and evolution of galactic disks. In a matching sample of GADGET and AREPO haloes we fit simulated gas disks with exponential profiles. We find that the cold gas disks formed using AREPO have systematically larger disk scale lengths and higher specific angular momenta than their GADGET counterparts. The reason for these differences is rooted in the inaccuracies of the SPH solver and calls for a reassessment of commonly adopted feedback prescriptions in cosmological simulations.

  5. Laparoscopic sacrocolpopexy versus transvaginal mesh for recurrent pelvic organ prolapse.

    Science.gov (United States)

    Iglesia, Cheryl B; Hale, Douglass S; Lucente, Vincent R

    2013-03-01

    Both expert surgeons agree with the following: (1) Surgical mesh, whether placed laparoscopically or transvaginally, is indicated for pelvic floor reconstruction in cases involving recurrent advanced pelvic organ prolapse. (2) Procedural expertise and experience gained from performing a high volume of cases is fundamentally necessary. Knowledge of outcomes and complications from an individual surgeon's audit of cases is also needed when discussing the risks and benefits of procedures and alternatives. Yet controversy still exists on how best to teach new surgical techniques and optimal ways to efficiently track outcomes, including subjective and objective cure of prolapse as well as perioperative complications. A mesh registry will be useful in providing data needed for surgeons. Cost factors are also a consideration since laparoscopic and especially robotic surgical mesh procedures are generally more costly than transvaginal mesh kits when operative time, extra instrumentation and length of stay are included. Long-term outcomes, particularly for transvaginal mesh procedures, are lacking. In conclusion, all surgery poses risks; however, patients should be made aware of the pros and cons of various routes of surgery as well as the potential risks and benefits of using mesh. Surgeons should provide patients with honest information about their own experience implanting mesh and also their experience dealing with mesh-related complications.

  6. Concomitant sublay mesh repair of umbilical hernia and abdominoplasty

    OpenAIRE

    2012-01-01

    Concomitant mesh repair of large umbilical hernias and abdominoplasty pose a serious risk of devascularizing the umbilical stalk. A technique of placing mesh in a sublay manner, deep to the fascial defect, for an umbilical herniorrhaphy to avoid damage to the deep umbilical perforators during an abdominoplasty is described.

  7. Scalable Video Streaming in Wireless Mesh Networks for Education

    Science.gov (United States)

    Liu, Yan; Wang, Xinheng; Zhao, Liqiang

    2011-01-01

    In this paper, a video streaming system for education based on a wireless mesh network is proposed. A wireless mesh network is a self-organizing, self-managing and reliable intelligent network, which allows educators to deploy a network quickly. Video streaming plays an important role in this system for multimedia data transmission. This new…

  8. Water Penetration through a Superhydrophobic Mesh During a Drop Impact.

    Science.gov (United States)

    Ryu, Seunggeol; Sen, Prosenjit; Nam, Youngsuk; Lee, Choongyeop

    2017-01-06

    When a water drop impacts a mesh having submillimeter pores, a part of the drop penetrates through the mesh if the impact velocity is sufficiently large. Here we show that different surface wettability, i.e., hydrophobicity and superhydrophobicity, leads to different water penetration dynamics on a mesh during drop impact. We show, despite the water repellence of a superhydrophobic surface, that water can penetrate a superhydrophobic mesh more easily (i.e., at a lower impact velocity) over a hydrophobic mesh via a penetration mechanism unique to a superhydrophobic mesh. On a superhydrophobic mesh, the water penetration can occur during the drop recoil stage, which appears at a lower impact velocity than the critical impact velocity for water penetration right upon impact. We propose that this unique water penetration on a superhydrophobic mesh can be attributed to the combination of the hydrodynamic focusing and the momentum transfer from the water drop when it is about to bounce off the surface, at which point the water drop retrieves most of its kinetic energy due to the negligible friction on superhydrophobic surfaces.

  9. Micro-mesh fabric pollination bags for switchgrass

    Science.gov (United States)

    Pollination bags for making controlled crosses between switchgrass plants were made from a polyester micro-mesh fabric with a mesh size of 41 µm which is smaller than the mean reported 43 µm diameter of switchgrass pollen. When used in paired plant crosses between switchgrass plants, the mean amoun...

  10. Mesh Processing in Medical-Image Analysis-a Tutorial

    DEFF Research Database (Denmark)

    Levine, Joshua A.; Paulsen, Rasmus Reinhold; Zhang, Yongjie

    2012-01-01

    Medical-image analysis requires an understanding of sophisticated scanning modalities, constructing geometric models, building meshes to represent domains, and downstream biological applications. These four steps form an image-to-mesh pipeline. For research in this field to progress, the imaging...

  11. SUPERCONVERGENCE ANALYSIS OF A NONCONFORMING TRIANGULAR ELEMENT ON ANISOTROPIC MESHES

    Institute of Scientific and Technical Information of China (English)

    Dongyang SHI; Hui LIANG; Caixia WANG

    2007-01-01

    The class of anisotropic meshes we conceived abandons the regular assumption. Some distinct properties of Carey's element are used to deal with the superconvergence for a class of twodimensional second-order elliptic boundary value problems on anisotropic meshes. The optimal results are obtained and numerical examples are given to confirm our theoretical analysis.

  12. Sen migration af mesh til colon efter laparoskopisk hernieoperation

    DEFF Research Database (Denmark)

    Rasmussen, Martin; Bisgaard, Thue

    2014-01-01

    Long-term complications after laparoscopic ventral hernia repair with mesh reinforcement are not well documented in the literature. We describe a case of a 63-year-old woman with repeated hernia operations due to a ventral hernia, which ultimately was complicated with mesh migration...

  13. Late mesh migration into the colon after laparoscopic herniotomy

    DEFF Research Database (Denmark)

    Rasmussen, Martin; Bisgaard, Thue

    2014-01-01

    Long-term complications after laparoscopic ventral hernia repair with mesh reinforcement are not well documented in the literature. We describe a case of a 63-year-old woman with repeated hernia operations due to a ventral hernia, which ultimately was complicated with mesh migration...

  14. Explicit inverse distance weighting mesh motion for coupled problems

    NARCIS (Netherlands)

    Witteveen, J.A.S.; Bijl, H.

    2009-01-01

    An explicit mesh motion algorithm based on inverse distance weighting interpolation is presented. The explicit formulation leads to a fast mesh motion algorithm and an easy implementation. In addition, the proposed point-by-point method is robust and flexible in case of large deformations, hanging n

  15. Conformal mesh deformations with Möbius transformations

    NARCIS (Netherlands)

    Vaxman, Amir; Müller, Christian; Weber, Ofir

    2015-01-01

    We establish a framework to design triangular and circular polygonal meshes by using face-based compatible Möbius transformations. Embracing the viewpoint of surfaces from circles, we characterize discrete conformality for such meshes, in which the invariants are circles, cross-ratios, and mutual in

  16. Sending policies in dynamic wireless mesh using network coding

    DEFF Research Database (Denmark)

    Pandi, Sreekrishna; Fitzek, Frank; Pihl, Jeppe

    2015-01-01

    This paper demonstrates the quick prototyping capabilities of the Python-Kodo library for network coding based performance evaluation and investigates the problem of data redundancy in a network coded wireless mesh with opportunistic overhearing. By means of several wireless meshed architectures ...

  17. Tangle-Free Finite Element Mesh Motion for Ablation Problems

    Science.gov (United States)

    Droba, Justin

    2016-01-01

    In numerical simulations involving boundaries that evolve in time, the primary challenge is updating the computational mesh to reflect the physical changes in the domain. In particular, the fundamental objective for any such \\mesh motion" scheme is to maintain mesh quality and suppress unphysical geometric anamolies and artifacts. External to a physical process of interest, mesh motion is an added component that determines the specifics of how to move the mesh given certain limited information from the main system. This paper develops a set of boundary conditions designed to eliminate tangling and internal collision within the context of PDE-based mesh motion (linear elasticity). These boundary conditions are developed for two- and three-dimensional meshes. The paper presents detailed algorithms for commonly occuring topological scenarios and explains how to apply them appropriately. Notably, the techniques discussed herein make use of none of the specifics of any particular formulation of mesh motion and thus are more broadly applicable. The two-dimensional algorithms are validated by an extensive verification procedure. Finally, many examples of diverse geometries in both two- and three-dimensions are shown to showcase the capabilities of the tangle-free boundary conditions.

  18. Communication performance of the Intel Touchstone DELTA mesh

    Energy Technology Data Exchange (ETDEWEB)

    Dunigan, T.H.

    1992-01-01

    The communication performance of the i860-based Intel DELTA mesh supercomputer is compared with the Intel iPSC/860 hypercube and the Ncube 6400 hypercube. Single and multiple hop communication bandwidth and latencies are measured. Concurrent communication speeds and speed under network load are also measured. File I/O performance of the mesh-attached Concurrent File System is measured.

  19. On Fault Tolerance of 3-Dimensional Mesh Networks

    Institute of Scientific and Technical Information of China (English)

    Gao-Cai Wang; Jian-Er Chen; Guo-Jun Wang

    2004-01-01

    In this paper, the concept of k-submesh and k-submesh connectivity fault tolerance model is proposed. And the fault tolerance of 3-D mesh networks is studied under a more realistic model in which each network node has an independent failure probability. It is first observed that if the node failure probability is fixed, then the connectivity probability of 3-D mesh networks can be arbitrarily small when the network size is sufficiently large. Thus, it is practically important for multicomputer system manufacturer to determine the upper bound for node failure probability when the probability of network connectivity and the network size are given.A novel technique is developed to formally derive lower bounds on the connectivity probability for 3-D mesh networks. The study shows that 3-D mesh networks of practical size can tolerate a large number of faulty nodes thus are reliable enough for multicomputer systems. A number of advantages of 3-D mesh networks over other popular network topologies are given. Compared to 2-D mesh networks, 3-D mesh networks are much stronger in tolerating faulty nodes, while for practical network size, the fault tolerance of 3-D mesh networks is comparable with that of hypercube networks but enjoys much lower node degree.

  20. Scalable Video Streaming in Wireless Mesh Networks for Education

    Science.gov (United States)

    Liu, Yan; Wang, Xinheng; Zhao, Liqiang

    2011-01-01

    In this paper, a video streaming system for education based on a wireless mesh network is proposed. A wireless mesh network is a self-organizing, self-managing and reliable intelligent network, which allows educators to deploy a network quickly. Video streaming plays an important role in this system for multimedia data transmission. This new…

  1. Carpet: Adaptive Mesh Refinement for the Cactus Framework

    Science.gov (United States)

    Schnetter, Erik; Hawley, Scott; Hawke, Ian

    2016-11-01

    Carpet is an adaptive mesh refinement and multi-patch driver for the Cactus Framework (ascl:1102.013). Cactus is a software framework for solving time-dependent partial differential equations on block-structured grids, and Carpet acts as driver layer providing adaptive mesh refinement, multi-patch capability, as well as parallelization and efficient I/O.

  2. The Superconvergence Phenomenon and Proof of the MAC Scheme for the Stokes Equations on Non-uniform Rectangular Meshes

    KAUST Repository

    Li, Jichun

    2014-12-02

    For decades, the widely used finite difference method on staggered grids, also known as the marker and cell (MAC) method, has been one of the simplest and most effective numerical schemes for solving the Stokes equations and Navier–Stokes equations. Its superconvergence on uniform meshes has been observed by Nicolaides (SIAM J Numer Anal 29(6):1579–1591, 1992), but the rigorous proof is never given. Its behavior on non-uniform grids is not well studied, since most publications only consider uniform grids. In this work, we develop the MAC scheme on non-uniform rectangular meshes, and for the first time we theoretically prove that the superconvergence phenomenon (i.e., second order convergence in the (Formula presented.) norm for both velocity and pressure) holds true for the MAC method on non-uniform rectangular meshes. With a careful and accurate analysis of various sources of errors, we observe that even though the local truncation errors are only first order in terms of mesh size, the global errors after summation are second order due to the amazing cancellation of local errors. This observation leads to the elegant superconvergence analysis even with non-uniform meshes. Numerical results are given to verify our theoretical analysis.

  3. A Family of Uniform Strain Tetrahedral Elements and a Method for Connecting Dissimilar Finite Element Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Dohrmann, C.R.; Heinstein, M.W.; Jung, J.; Key, S.W.

    1999-01-01

    This report documents a collection of papers on a family of uniform strain tetrahedral finite elements and their connection to different element types. Also included in the report are two papers which address the general problem of connecting dissimilar meshes in two and three dimensions. Much of the work presented here was motivated by the development of the tetrahedral element described in the report "A Suitable Low-Order, Eight-Node Tetrahedral Finite Element For Solids," by S. W. Key {ital et al.}, SAND98-0756, March 1998. Two basic issues addressed by the papers are: (1) the performance of alternative tetrahedral elements with uniform strain and enhanced uniform strain formulations, and (2) the proper connection of tetrahedral and other element types when two meshes are "tied" together to represent a single continuous domain.

  4. White Dwarf Mergers on Adaptive Meshes I. Methodology and Code Verification

    CERN Document Server

    Katz, Max P; Calder, Alan C; Swesty, F Douglas; Almgren, Ann S; Zhang, Weiqun

    2015-01-01

    The Type Ia supernova progenitor problem is one of the most perplexing and exciting problems in astrophysics, requiring detailed numerical modeling to complement observations of these explosions. One possible progenitor that has merited recent theoretical attention is the white dwarf merger scenario, which has the potential to naturally explain many of the observed characteristics of Type Ia supernovae. To date there have been relatively few self-consistent simulations of merging white dwarf systems using mesh-based hydrodynamics. This is the first paper in a series describing simulations of these systems using a hydrodynamics code with adaptive mesh refinement. In this paper we describe our numerical methodology and discuss our implementation in the compressible hydrodynamics code CASTRO, which solves the Euler equations, and the Poisson equation for self-gravity, and couples the gravitational and rotation forces to the hydrodynamics. Standard techniques for coupling gravitation and rotation forces to the hy...

  5. 3D level set methods for evolving fronts on tetrahedral meshes with adaptive mesh refinement

    Science.gov (United States)

    Morgan, Nathaniel R.; Waltz, Jacob I.

    2017-05-01

    The level set method is commonly used to model dynamically evolving fronts and interfaces. In this work, we present new methods for evolving fronts with a specified velocity field or in the surface normal direction on 3D unstructured tetrahedral meshes with adaptive mesh refinement (AMR). The level set field is located at the nodes of the tetrahedral cells and is evolved using new upwind discretizations of Hamilton-Jacobi equations combined with a Runge-Kutta method for temporal integration. The level set field is periodically reinitialized to a signed distance function using an iterative approach with a new upwind gradient. The details of these level set and reinitialization methods are discussed. Results from a range of numerical test problems are presented.

  6. An unstructured-mesh atmospheric model for nonhydrostatic dynamics: Towards optimal mesh resolution

    Science.gov (United States)

    Szmelter, Joanna; Zhang, Zhao; Smolarkiewicz, Piotr K.

    2015-08-01

    The paper advances the limited-area anelastic model (Smolarkiewicz et al. (2013) [45]) for investigation of nonhydrostatic dynamics in mesoscale atmospheric flows. New developments include the extension to a tetrahedral-based median-dual option for unstructured meshes and a static mesh adaptivity technique using an error indicator based on inherent properties of the Multidimensional Positive Definite Advection Transport Algorithm (MPDATA). The model employs semi-implicit nonoscillatory forward-in-time integrators for soundproof PDEs, built on MPDATA and a robust non-symmetric Krylov-subspace elliptic solver. Finite-volume spatial discretisation adopts an edge-based data structure. Simulations of stratified orographic flows and the associated gravity-wave phenomena in media with uniform and variable dispersive properties verify the advancement and demonstrate the potential of heterogeneous anisotropic discretisation with large variation in spatial resolution for study of complex stratified flows that can be computationally unattainable with regular grids.

  7. Experimental studies of micromegas detectors with different micro-meshes

    Institute of Scientific and Technical Information of China (English)

    YANG He-Run; HU Bi-Tao; ZHANG Xiao-Dang; ZOU Chun-Yan

    2011-01-01

    The structure of micromegas (micro-mesh gaseous structure) detectors with different micro-meshes of stainless steel wire woven netting and Ni foil has been presented. The counting rates, energy resolution, gain, discharge probability and time resolution have been measured. Wider counter plateaus and gain for the developed detector were obtained. Excellent energy resolution of the micromegas detector, 17% (FWHM) based on Ni foil micro-mesh and 25% (FWHM) based on stainless steel wire woven netting micro-mesh, has been obtained for the 5.9 keV photon peak of the 55Fe X-ray source in an Ar/CO2(10%) gas mixture. The best time resolution at -620 V micro-mesh voltage and -870 V drift voltage is 14.8 ns for cosmic rays in an Ar/CO2 (10%) gas mixture. These results satisfy the basic demand of the micromegas detector preliminary design.

  8. Migrated Mesh Plug Masquerading as a Bladder Tumor

    Science.gov (United States)

    Dajani, Daoud; Aron, Monish

    2017-01-01

    Abstract Background: The purpose of this case presentation is to demonstrate how erosion of mesh into the bladder can initially present with the same symptoms as bladder malignancy. Case Presentation: A 62-year-old Hispanic male presented with 2 years of hematuria along with imaging concerning for a bladder tumor. The patient underwent cystoscopy with biopsy of a lesion at the anterior bladder. It was ultimately determined that a mesh plug from a prior hernia repair had migrated into the bladder. The mesh plug was excised using the Da Vinci Si robot, which allowed for efficient mobilization of the bladder and other anatomic structures, as well as rapid recovery. Conclusion: Our case demonstrates the need to consider mesh erosion as a cause of hematuria and, furthermore, shows how the robotic approach can help facilitate excision of migrated mesh into the bladder. PMID:28164159

  9. Adaptive-mesh algorithms for computational fluid dynamics

    Science.gov (United States)

    Powell, Kenneth G.; Roe, Philip L.; Quirk, James

    1993-01-01

    The basic goal of adaptive-mesh algorithms is to distribute computational resources wisely by increasing the resolution of 'important' regions of the flow and decreasing the resolution of regions that are less important. While this goal is one that is worthwhile, implementing schemes that have this degree of sophistication remains more of an art than a science. In this paper, the basic pieces of adaptive-mesh algorithms are described and some of the possible ways to implement them are discussed and compared. These basic pieces are the data structure to be used, the generation of an initial mesh, the criterion to be used to adapt the mesh to the solution, and the flow-solver algorithm on the resulting mesh. Each of these is discussed, with particular emphasis on methods suitable for the computation of compressible flows.

  10. Feature-preserving surface mesh smoothing via suboptimal Delaunay triangulation.

    Science.gov (United States)

    Gao, Zhanheng; Yu, Zeyun; Holst, Michael

    2013-01-01

    A method of triangular surface mesh smoothing is presented to improve angle quality by extending the original optimal Delaunay triangulation (ODT) to surface meshes. The mesh quality is improved by solving a quadratic optimization problem that minimizes the approximated interpolation error between a parabolic function and its piecewise linear interpolation defined on the mesh. A suboptimal problem is derived to guarantee a unique, analytic solution that is significantly faster with little loss in accuracy as compared to the optimal one. In addition to the quality-improving capability, the proposed method has been adapted to remove noise while faithfully preserving sharp features such as edges and corners of a mesh. Numerous experiments are included to demonstrate the performance of the method.

  11. Challenges in Second-Generation Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    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.

  12. Challenges in Second-Generation Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    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.

  13. Use of mesh in laparoscopic paraesophageal hernia repair

    DEFF Research Database (Denmark)

    Müller-Stich, Beat P.; Kenngott, Hannes G.; Gondan, Matthias;

    2015-01-01

    Introduction. Mesh augmentation seems to reduce recurrences following laparoscopic paraesophageal hernia repair (LPHR). However, there is an uncertain risk of mesh-associated complications. Risk-benefit analysis might solve the dilemma. Materials and Methods. A systematic literature search...... was performed to identify randomized controlled trials (RCTs) and observational clinical studies (OCSs) comparing laparoscopic mesh-augmented hiatoplasty (LMAH) with laparoscopic mesh-free hiatoplasty (LH) with regard to recurrences and complications. Random effects meta-analyses were performed to determine...... potential benefits of LMAH. All data regarding LMAH were used to estimate risk of mesh-associated complications. Risk-benefit analysis was performed using a Markov Monte Carlo decision-analytic model. Results. Meta-analysis of 3 RCTs and 9 OCSs including 915 patients revealed a significantly lower...

  14. Comparison and combination of several MeSH indexing approaches.

    Science.gov (United States)

    Yepes, Antonio Jose Jimeno; Mork, James G; Demner-Fushman, Dina; Aronson, Alan R

    2013-01-01

    MeSH indexing of MEDLINE is becoming a more difficult task for the group of highly qualified indexing staff at the US National Library of Medicine, due to the large yearly growth of MEDLINE and the increasing size of MeSH. Since 2002, this task has been assisted by the Medical Text Indexer or MTI program. We extend previous machine learning analysis by adding a more diverse set of MeSH headings targeting examples where MTI has been shown to perform poorly. Machine learning algorithms exceed MTI's performance on MeSH headings that are used very frequently and headings for which the indexing frequency is very low. We find that when we combine the MTI suggestions and the prediction of the learning algorithms, the performance improves compared to any single method for most of the evaluated MeSH headings.

  15. Finite Element Meshes Auto-Generation for the Welted Bifurcation

    Institute of Scientific and Technical Information of China (English)

    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.

  16. Kinetic Solvers with Adaptive Mesh in Phase Space

    CERN Document Server

    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...

  17. Laparoscopic repair of congenital pleuroperitoneal hernia using a polypropylene mesh in a dog

    Directory of Open Access Journals (Sweden)

    H.F. Hartmann

    2015-12-01

    Full Text Available ABSTRACT Pleuroperitoneal hernias are the most uncommon type of diaphragmatic hernias in dogs and cats. The treatment of choice is surgery and may involve the use of prosthetic implant through celiotomy. In the current report, laparoscopic repair of a congenital pleuroperitoneal hernia using polypropylene mesh in a dog is described. The surgery was feasible. Appropriate reduction of the hernia was carried out and no complications were noted.

  18. Resorbable biosynthetic mesh for crural reinforcement during hiatal hernia repair.

    Science.gov (United States)

    Alicuben, Evan T; Worrell, Stephanie G; DeMeester, Steven R

    2014-10-01

    The use of mesh to reinforce crural closure during hiatal hernia repair is controversial. Although some studies suggest that using synthetic mesh can reduce recurrence, synthetic mesh can erode into the esophagus and in our opinion should be avoided. Studies with absorbable or biologic mesh have not proven to be of benefit for recurrence. The aim of this study was to evaluate the outcome of hiatal hernia repair with modern resorbable biosynthetic mesh in combination with adjunct tension reduction techniques. We retrospectively analyzed all patients who had crural reinforcement during repair of a sliding or paraesophageal hiatal hernia with Gore BioA resorbable mesh. Objective follow-up was by videoesophagram and/or esophagogastroduodenoscopy. There were 114 patients. The majority of operations (72%) were laparoscopic primary repairs with all patients receiving a fundoplication. The crura were closed primarily in all patients and reinforced with a BioA mesh patch. Excessive tension prompted a crural relaxing incision in four per cent and a Collis gastroplasty in 39 per cent of patients. Perioperative morbidity was minor and unrelated to the mesh. Median objective follow-up was one year, but 18 patients have objective follow-up at two or more years. A recurrent hernia was found in one patient (0.9%) three years after repair. The use of crural relaxing incisions and Collis gastroplasty in combination with crural reinforcement with resorbable biosynthetic mesh is associated with a low early hernia recurrence rate and no mesh-related complications. Long-term follow-up will define the role of these techniques for hiatal hernia repair.

  19. Behaviour of a new composite mesh for the repair of full-thickness abdominal wall defects in a rabbit model.

    Directory of Open Access Journals (Sweden)

    Gemma Pascual

    Full Text Available INTRODUCTION: Composite biomaterials designed for the repair of abdominal wall defects are composed of a mesh component and a laminar barrier in contact with the visceral peritoneum. This study assesses the behaviour of a new composite mesh by comparing it with two latest-generation composites currently used in clinical practice. METHODS: Defects (7x5cm created in the anterior abdominal wall of New Zealand White rabbits were repaired using a polypropylene mesh and the composites: Physiomesh(TM; Ventralight(TM and a new composite mesh with a three-dimensional macroporous polyester structure and an oxidized collagen/chitosan barrier. Animals were sacrificed on days 14 and 90 postimplant. Specimens were processed to determine host tissue incorporation, gene/protein expression of neo-collagens (RT-PCR/immunofluorescence, macrophage response (RAM-11-immunolabelling and biomechanical resistance. On postoperative days 7/14, each animal was examined laparoscopically to quantify adhesions between the visceral peritoneum and implant. RESULTS: The new composite mesh showed the lowest incidence of seroma in the short term. At each time point, the mesh surface covered with adhesions was greater in controls than composites. By day 14, the implants were fully infiltrated by a loose connective tissue that became denser over time. At 90 days, the peritoneal mesh surface was lined with a stable mesothelium. The new composite mesh induced more rapid tissue maturation than Physiomesh(TM, giving rise to a neoformed tissue containing more type I collagen. In Ventralight(TM the macrophage reaction was intense and significantly greater than the other composites at both follow-up times. Tensile strengths were similar for each biomaterial. CONCLUSIONS: All composites showed optimal peritoneal behaviour, inducing good peritoneal regeneration and scarce postoperative adhesion formation. A greater foreign body reaction was observed for Ventralight(TM. All composites induced

  20. Multiobjective Genetic Algorithm for QoS Routing in Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Wilson Soto

    2013-11-01

    Full Text Available The wireless mesh network is the type of network more used currently, the same as show interesting challenges in the topic of investigation. One of the challenges is as improve the capability of a network to provide better service to selected network traffic over various technologies. This requires keep in mind variables such as delay, jitter, packet loss and band width. This type of challenge where is necessary to optimize several variables becomes a combinatorial and computational complex problem. A method for solve this type of problems are the genetic algorithms. In this work we show a multiobjective genetic algorithm for quality of service in routing in wireless mesh networks. The proposed genetic algorithm besides has the advantage of use the Pareto frontier algorithm with the divide and conquer technique and the knee algorithm for to select an only solution of the problem. The paths found for the proposed algorithm demonstrate that achieve the purpose to improve the quality of service in routing in wireless mesh networks.

  1. 集螺旋阴极笼型阴极网状阴极为一体的新型阴极(Z阴极)%A New Type of the Cathode Combining the Properties of Helix Cathode,Cage Cathode and Mesh Cathode

    Institute of Scientific and Technical Information of China (English)

    张新富

    2001-01-01

    This paper describes the derivation ,definition,properties and application of the Z cathode The conversion and replacement among Z cathode ,Helix cathode,cage cathode and mesh cathode are also discussed.%本文阐述了Z阴极的由来、定义、特性和运用,以及Z阴极与螺旋阴极、笼型阴极、网状阴极之间的转换和代替。

  2. How MESSENGER Meshes Simulations and Games with Citizen Science

    Science.gov (United States)

    Hirshon, B.; Chapman, C. R.; Edmonds, J.; Goldstein, J.; Hallau, K. G.; Solomon, S. C.; Vanhala, H.; Weir, H. M.; Messenger Education; Public Outreach (Epo) Team

    2010-12-01

    How MESSENGER Meshes Simulations and Games with Citizen Science In the film The Last Starfighter, an alien civilization grooms their future champion—a kid on Earth—using a video game. As he gains proficiency in the game, he masters the skills he needs to pilot a starship and save their civilization. The NASA MESSENGER Education and Public Outreach (EPO) Team is using the same tactic to train citizen scientists to help the Science Team explore the planet Mercury. We are building a new series of games that appear to be designed primarily for fun, but that guide players through a knowledge and skill set that they will need for future science missions in support of MESSENGER mission scientists. As players score points, they gain expertise. Once they achieve a sufficiently high score, they will be invited to become participants in Mercury Zoo, a new program being designed by Zooniverse. Zooniverse created Galaxy Zoo and Moon Zoo, programs that allow interested citizens to participate in the exploration and interpretation of galaxy and lunar data. Scientists use the citizen interpretations to further refine their exploration of the same data, thereby narrowing their focus and saving precious time. Mercury Zoo will be designed with input from the MESSENGER Science Team. This project will not only support the MESSENGER mission, but it will also add to the growing cadre of informed members of the public available to help with other citizen science projects—building on the concept that engaged, informed citizens can help scientists make new discoveries. The MESSENGER EPO Team comprises individuals from the American Association for the Advancement of Science (AAAS); Carnegie Academy for Science Education (CASE); Center for Educational Resources (CERES) at Montana State University (MSU) - Bozeman; National Center for Earth and Space Science Education (NCESSE); Johns Hopkins University Applied Physics Laboratory (JHU/APL); National Air and Space Museum (NASM); Science

  3. Ordering the mob: Insights into replicon and MOB typing schemes from analysis of a curated dataset of publicly available plasmids.

    Science.gov (United States)

    Orlek, Alex; Phan, Hang; Sheppard, Anna E; Doumith, Michel; Ellington, Matthew; Peto, Tim; Crook, Derrick; Walker, A Sarah; Woodford, Neil; Anjum, Muna F; Stoesser, Nicole

    2017-03-09

    Plasmid typing can provide insights into the epidemiology and transmission of plasmid-mediated antibiotic resistance. The principal plasmid typing schemes are replicon typing and MOB typing, which utilize variation in replication loci and relaxase proteins respectively. Previous studies investigating the proportion of plasmids assigned a type by these schemes ('typeability') have yielded conflicting results; moreover, thousands of plasmid sequences have been added to NCBI in recent years, without consistent annotation to indicate which sequences represent complete plasmids. Here, a curated dataset of complete Enterobacteriaceae plasmids from NCBI was compiled, and used to assess the typeability and concordance of in silico replicon and MOB typing schemes. Concordance was assessed at hierarchical replicon type resolutions, from replicon family-level to plasmid multilocus sequence type (pMLST)-level, where available. We found that 85% and 65% of the curated plasmids could be replicon and MOB typed, respectively. Overall, plasmid size and the number of resistance genes were significant independent predictors of replicon and MOB typing success. We found some degree of non-concordance between replicon families and MOB types, which was only partly resolved when partitioning plasmids into finer-resolution groups (replicon and pMLST types). In some cases, non-concordance was attributed to ambiguous boundaries between MOBP and MOBQ types; in other cases, backbone mosaicism was considered a more plausible explanation. β-lactamase resistance genes tended not to show fidelity to a particular plasmid type, though some previously reported associations were supported. Overall, replicon and MOB typing schemes are likely to continue playing an important role in plasmid analysis, but their performance is constrained by the diverse and dynamic nature of plasmid genomes.

  4. Reaction rates for reaction-diffusion kinetics on unstructured meshes

    Science.gov (United States)

    Hellander, Stefan; Petzold, Linda

    2017-02-01

    The reaction-diffusion master equation is a stochastic model often utilized in the study of biochemical reaction networks in living cells. It is applied when the spatial distribution of molecules is important to the dynamics of the system. A viable approach to resolve the complex geometry of cells accurately is to discretize space with an unstructured mesh. Diffusion is modeled as discrete jumps between nodes on the mesh, and the diffusion jump rates can be obtained through a discretization of the diffusion equation on the mesh. Reactions can occur when molecules occupy the same voxel. In this paper, we develop a method for computing accurate reaction rates between molecules occupying the same voxel in an unstructured mesh. For large voxels, these rates are known to be well approximated by the reaction rates derived by Collins and Kimball, but as the mesh is refined, no analytical expression for the rates exists. We reduce the problem of computing accurate reaction rates to a pure preprocessing step, depending only on the mesh and not on the model parameters, and we devise an efficient numerical scheme to estimate them to high accuracy. We show in several numerical examples that as we refine the mesh, the results obtained with the reaction-diffusion master equation approach those of a more fine-grained Smoluchowski particle-tracking model.

  5. Multiresolution mesh segmentation based on surface roughness and wavelet analysis

    Science.gov (United States)

    Roudet, Céline; Dupont, Florent; Baskurt, Atilla

    2007-01-01

    During the last decades, the three-dimensional objects have begun to compete with traditional multimedia (images, sounds and videos) and have been used by more and more applications. The common model used to represent them is a surfacic mesh due to its intrinsic simplicity and efficacity. In this paper, we present a new algorithm for the segmentation of semi-regular triangle meshes, via multiresolution analysis. Our method uses several measures which reflect the roughness of the surface for all meshes resulting from the decomposition of the initial model into different fine-to-coarse multiresolution meshes. The geometric data decomposition is based on the lifting scheme. Using that formulation, we have compared various interpolant prediction operators, associated or not with an update step. For each resolution level, the resulting approximation mesh is then partitioned into classes having almost constant roughness thanks to a clustering algorithm. Resulting classes gather regions having the same visual appearance in term of roughness. The last step consists in decomposing the mesh into connex groups of triangles using region growing ang merging algorithms. These connex surface patches are of particular interest for adaptive mesh compression, visualisation, indexation or watermarking.

  6. Probabilistic analysis on fault tolerance of 3-Dimensional mesh networks

    Institute of Scientific and Technical Information of China (English)

    王高才; 陈建二; 王国军; 陈松乔

    2003-01-01

    The probability model is used to analyze the fault tolerance of mesh. To simplify its analysis, it is as-sumed that the failure probability of each node is independent. A 3-D mesh is partitioned into smaller submeshes,and then the probability with which each submesh satisfies the defined condition is computed. If each submesh satis-fies the condition, then the whole mesh is connected. Consequently, the probability that a 3-D mesh is connected iscomputed assuming each node has a failure probability. Mathematical methods are used to derive a relationship be-tween network node failure probability and network connectivity probability. The calculated results show that the 3-D mesh networks can remain connected with very high probability in practice. It is formally proved that when thenetwork node failure probability is boutded by 0.45 %, the 3-D mesh networks of more than three hundred thousandnodes remain connected with probability larger than 99 %. The theoretical results show that the method is a power-ful technique to calculate the lower bound of the connectivity probability of mesh networks.

  7. Fixation of Light Weight Polypropylene Mesh with n-Butyl-2-cyanocrylate in Pelvic Floor Surgery: Experimental Design Approach in Sheep for Effectiveness Evaluation

    Directory of Open Access Journals (Sweden)

    Sandra Barbosa

    2015-01-01

    Full Text Available Objective. The aim of this study was to find a proper experimental design and to evaluate n-butyl-2-cyanoacrylate (Histoacryl as a fixation method for a light-weight and large pore PP mesh (Synthetic PP Mesh-1 using the sheep as an animal model. Methods. Posterior vaginal implantation by means of episiotomy was used to implant 8 ewes which were evaluated macroscopically and histologically at 3 months (n=4 and 6 months (n=4 post-surgery. In previous pilot studies anterior vaginal implantation was evaluated, as well as different synthetic mesh materials, sizes and fixation methods (n=1 to 3 during three weeks. In all cases a clinical evaluation of the animal was performed. Results. A reduction in the mesh size (Synthetic PP Mesh-1 together with precise application of the surgical glue Histoacryl to fix the mesh yielded significantly better histocompatibility results (P<0.01 compared to larger size or other fixation methods. Conclusion. The combination of Synthetic PP Mesh-1 with Histoacryl offered a high degree of graft integration without vaginal ulceration and a minimal foreign body reaction, being the sheep a proper animal model to test these types of medical devices.

  8. Different tissue reaction of oesophagus and diaphragm after mesh hiatoplasty. Results of an animal study

    Directory of Open Access Journals (Sweden)

    Rosch Raphael

    2008-04-01

    Full Text Available Abstract Background Laparoscopic mesh-reinforcement of the hiatal region in the treatment of gastroesophageal reflux disease (GERD and paraesophageal hernia (PEH reduces the risk of recurrence. However, there are still controversies about the technique of mesh placement, shape, structure and material. We therefore compared tissue integration and scar formation after implantation of two different polypropylene-meshes in a rabbit model. Methods A total of 20 female chinchilla rabbits were included in this study. Two different meshes (Polypropylene PP, Polyglecaprone 25 Composite PP-PG were implanted on the abdominal diaphragm around the oesophagus. After 3 months the implanted meshes were excised en-bloc. Histological and morphological analyses were carried out accordingly proliferation rate, apoptosis and collagen type I/III ratio. Results Regarding proliferation rate of oesophagus PP (9.31 ± 3.4% and PP-PG (13.26 ± 2.54% differ in a significant (p = 0.0097 way. In the diaphragm we found a significant (p = 0.00066 difference between PP (9.43 ± 1.45% and PP-PG (18.73 ± 5.92% respectively. Comparing oesophagus and diaphragm we could prove a significant difference within PP-PG-group (p = 0.0195. Within PP-group the difference reached no statistical significance (p = 0.88. We found analogous results regarding apoptosis. Furthermore, there is a significant (p = 0.00013 difference of collagen type I/III ratio in PP-PG (12.28 ± 0.8 compared to PP (8.44 ± 1,63 in case of oesophageal tissue. Concerning diaphragm we found a significant difference (p = 0.000099 between PP-PG (8.85 ± 0.81 and PP (6.32 ± 1.07 as well. Conclusion The histologic and morphologic characteristics after prosthetic enforcement of the hiatus in this animal model show a more distinct tissue integration using PP-PG compared to PP. Additionally, different wound healing and remodelling capability influence tissue integration of the mesh in diaphragm and oesophagus.

  9. A lumped mass nonconforming finite element method for nonlinear parabolic integro-differential equations on anisotropic meshes

    Institute of Scientific and Technical Information of China (English)

    SHI Dong-yang; WANG Hui-min; LI Zhi-yan

    2009-01-01

    A lumped mass approximation scheme of a low order Crouzeix-Raviart type nonconforming triangular finite element is proposed to a kind of nonlinear parabolic integro-differential equations. The L2 error estimate is derived on anisotropic meshes without referring to the traditional nonclassical elliptic projection.

  10. Isotropic 2D quadrangle meshing with size and orientation control

    KAUST Repository

    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.

  11. Vertex Normals and Face Curvatures of Triangle Meshes

    KAUST Repository

    Sun, Xiang

    2016-08-12

    This study contributes to the discrete differential geometry of triangle meshes, in combination with discrete line congruences associated with such meshes. In particular we discuss when a congruence defined by linear interpolation of vertex normals deserves to be called a ʼnormal’ congruence. Our main results are a discussion of various definitions of normality, a detailed study of the geometry of such congruences, and a concept of curvatures and shape operators associated with the faces of a triangle mesh. These curvatures are compatible with both normal congruences and the Steiner formula.

  12. Laparoscopic sacrocolpopexy: how low does the mesh go?

    Science.gov (United States)

    Wong, V; Guzman Rojas, R; Shek, K L; Chou, D; Moore, K H; Dietz, H P

    2017-03-01

    Laparoscopic sacrocolpopexy is becoming an increasingly popular surgical approach for repair of apical vaginal prolapse. The aim of this study was to document the postoperative anterior mesh position after laparoscopic sacrocolpopexy and to investigate the relationship between mesh location and anterior compartment support. This was an external audit of patients who underwent laparoscopic sacrocolpopexy for apical prolapse ≥ Stage 2 or advanced prolapse ≥ Stage 3, between January 2005 and June 2012. All patients were assessed with a standardized interview, clinical assessment using the International Continence Society Pelvic Organ Prolapse quantification and four-dimensional transperineal ultrasound to evaluate pelvic organ support and mesh location. Mesh position was assessed with respect to the symphysis pubis whilst distal mesh mobility was assessed using the formula √[(XValsalva - Xrest )(2) + (YValsalva - Yrest )(2) ], where X is the horizontal distance and Y is the vertical distance between the mesh and the inferior symphyseal margin, measured at rest and on Valsalva. Ninety-seven women were assessed at a mean follow-up of 3.01 (range, 0.13-6.87) years after laparoscopic sacrocolpopexy, 88% (85/97) of whom considered themselves to be cured or improved, and none had required reoperation. On clinical examination, prolapse recurrence in the apical compartment was not diagnosed in any patient; however, 60 (62%) had recurrence in the anterior compartment and 43 (44%) in the posterior compartment. On ultrasound examination, mesh was visualized in the anterior compartment in 60 patients. Both mesh position and mobility on Valsalva were significantly associated with recurrent cystocele on clinical and on ultrasound assessment (all P < 0.01). For every mm that the mesh was located further from the bladder neck on Valsalva, the likelihood of cystocele recurrence increased by 6-7%. At an average follow-up of 3 years, laparoscopic sacrocolpopexy was highly

  13. Adaptive mesh refinement for stochastic reaction-diffusion processes

    Science.gov (United States)

    Bayati, Basil; Chatelain, Philippe; Koumoutsakos, Petros

    2011-01-01

    We present an algorithm for adaptive mesh refinement applied to mesoscopic stochastic simulations of spatially evolving reaction-diffusion processes. The transition rates for the diffusion process are derived on adaptive, locally refined structured meshes. Convergence of the diffusion process is presented and the fluctuations of the stochastic process are verified. Furthermore, a refinement criterion is proposed for the evolution of the adaptive mesh. The method is validated in simulations of reaction-diffusion processes as described by the Fisher-Kolmogorov and Gray-Scott equations.

  14. Engagement of Metal Debris into a Gear Mesh

    Science.gov (United States)

    Handschuh, Robert F.; Krantz, Timothy L.

    2010-01-01

    A series of bench top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock, and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

  15. Watermarking on 3D mesh based on spherical wavelet transform

    Institute of Scientific and Technical Information of China (English)

    金剑秋; 戴敏雅; 鲍虎军; 彭群生

    2004-01-01

    In this paper we propose a robust watermarking algorithm for 3D mesh. The algorithm is based on spherical wavelet transform. Our basic idea is to decompose the original mesh into a series of details at different scales by using spherical wavelet transform; the watermark is then embedded into the different levels of details. The embedding process includes: global sphere parameterization, spherical uniform sampling, spherical wavelet forward transform, embedding watermark, spherical wavelet inverse transform, and at last resampling the mesh watermarked to recover the topological connectivity of the original model. Experiments showed that our algorithm can improve the capacity of the watermark and the robustness of watermarking against attacks.

  16. Hex-dominant mesh generation using 3D constrained triangulation

    Energy Technology Data Exchange (ETDEWEB)

    OWEN,STEVEN J.

    2000-05-30

    A method for decomposing a volume with a prescribed quadrilateral surface mesh, into a hexahedral-dominated mesh is proposed. With this method, known as Hex-Morphing (H-Morph), an initial tetrahedral mesh is provided. Tetrahedral are transformed and combined starting from the boundary and working towards the interior of the volume. The quadrilateral faces of the hexahedra are treated as internal surfaces, which can be recovered using constrained triangulation techniques. Implementation details of the edge and face recovery process are included. Examples and performance of the H-Morph algorithm are also presented.

  17. An unstructured-mesh atmospheric model for nonhydrostatic dynamics

    Science.gov (United States)

    Smolarkiewicz, Piotr K.; Szmelter, Joanna; Wyszogrodzki, Andrzej A.

    2013-12-01

    A three-dimensional semi-implicit edge-based unstructured-mesh model is developed that integrates nonhydrostatic anelastic equations, suitable for simulation of small-to-mesoscale atmospheric flows. The model builds on nonoscillatory forward-in-time MPDATA approach using finite-volume discretization and admitting unstructured meshes with arbitrarily shaped cells. The numerical advancements are evaluated with canonical simulations of convective planetary boundary layer and strongly (stably) stratified orographic flows, epitomizing diverse aspects of highly nonlinear nonhydrostatic dynamics. The unstructured-mesh solutions are compared to equivalent results generated with an established structured-grid model and observation.

  18. Stable highly hydrophobic and oleophilic meshes for oil water separation

    Science.gov (United States)

    Wang, Qingjun; Cui, Zhe; Xiao, Yi; Chen, Qingmin

    2007-09-01

    This paper describes a simple method for fabricating both highly hydrophobic and oleophilic meshes by coating thin fluoro-containing films. The static contact angle of such meshes is greater than 150° for water, and close to 0° for kerosene, xylene and toluene. These meshes can separate water from oil effectively without resorting to any extra power or chemical agent. Moreover, they exhibited stable water resisting, anti-chemical erosion and anti-hot aging properties. It promises as a candidate for the separation of oil and water.

  19. Procedure for the automatic mesh generation of innovative gear teeth

    Directory of Open Access Journals (Sweden)

    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.

  20. Expected Transmission Energy Route Metric for Wireless Mesh Senor Networks

    Directory of Open Access Journals (Sweden)

    YanLiang Jin

    2011-01-01

    Full Text Available Mesh is a network topology that achieves high throughput and stable intercommunication. With great potential, it is expected to be the key architecture of future networks. Wireless sensor networks are an active research area with numerous workshops and conferences arranged each year. The overall performance of a WSN highly depends on the energy consumption of the network. This paper designs a new routing metric for wireless mesh sensor networks. Results from simulation experiments reveal that the new metric algorithm improves the energy balance of the whole network and extends the lifetime of wireless mesh sensor networks (WMSNs.

  1. Layer-adapted meshes for reaction-convection-diffusion problems

    CERN Document Server

    Linß, Torsten

    2010-01-01

    This book on numerical methods for singular perturbation problems - in particular, stationary reaction-convection-diffusion problems exhibiting layer behaviour is devoted to the construction and analysis of layer-adapted meshes underlying these numerical methods. A classification and a survey of layer-adapted meshes for reaction-convection-diffusion problems are included. This structured and comprehensive account of current ideas in the numerical analysis for various methods on layer-adapted meshes is addressed to researchers in finite element theory and perturbation problems. Finite differences, finite elements and finite volumes are all covered.

  2. Multiphase flow of immiscible fluids on unstructured moving meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam;

    2012-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization...... that the underlying discretization matches the physics and avoids the additional book-keeping required in grid-based methods where multiple fluids may occupy the same cell. Our Lagrangian approach naturally leads us to adopt a finite element approach to simulation, in contrast to the finite volume approaches adopted...

  3. Moving mesh cosmology: tracing cosmological gas accretion

    CERN Document Server

    Nelson, Dylan; Genel, Shy; Sijacki, Debora; Keres, Dusan; Springel, Volker; Hernquist, Lars; 10.1093/mnras/sts595

    2013-01-01

    We investigate the nature of gas accretion onto haloes and galaxies at z=2 using cosmological hydrodynamic simulations run with the moving mesh code AREPO. Implementing a Monte Carlo tracer particle scheme to determine the origin and thermodynamic history of accreting gas, we make quantitative comparisons to an otherwise identical simulation run with the smoothed particle hydrodynamics (SPH) code GADGET-3. Contrasting these two numerical approaches, we find significant physical differences in the thermodynamic history of accreted gas in haloes above 10^10.5 solar masses. In agreement with previous work, GADGET simulations show a cold fraction near unity for galaxies forming in massive haloes, implying that only a small percentage of accreted gas heats to an appreciable fraction of the virial temperature during accretion. The same galaxies in AREPO show a much lower cold fraction, <20% in haloes above 10^11 solar masses. This results from a hot gas accretion rate which, at this same halo mass, is an order o...

  4. Streaming Compression of Tetrahedral Volume Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Isenburg, M; Lindstrom, P; Gumhold, S; Shewchuk, J

    2005-11-21

    Geometry processing algorithms have traditionally assumed that the input data is entirely in main memory and available for random access. This assumption does not scale to large data sets, as exhausting the physical memory typically leads to IO-inefficient thrashing. Recent works advocate processing geometry in a 'streaming' manner, where computation and output begin as soon as possible. Streaming is suitable for tasks that require only local neighbor information and batch process an entire data set. We describe a streaming compression scheme for tetrahedral volume meshes that encodes vertices and tetrahedra in the order they are written. To keep the memory footprint low, the compressor is informed when vertices are referenced for the last time (i.e. are finalized). The compression achieved depends on how coherent the input order is and how many tetrahedra are buffered for local reordering. For reasonably coherent orderings and a buffer of 10,000 tetrahedra, we achieve compression rates that are only 25 to 40 percent above the state-of-the-art, while requiring drastically less memory resources and less than half the processing time.

  5. On the dynamics of entailment-meshes

    Science.gov (United States)

    Medina Martins, Pedro Roberto

    1999-03-01

    One of the most puzzling problems that general psychology has always faced, has been concerned with the question of human psychodynamics, with its possible `mechanisms', motivations, `inner' and `outer' actions, etc., briefly, what we usually embrace under the general and vague label "mental processes." Together with its `rational' part, a great deal of such processes is pervaded by an `irrationality' whose influences upon each of us not only remain still obscure but also show to be highly dependent on each of our living experiments/experiences as well as on the way we have interpreted them. Thus, difficult to be treated by the methods of the classical physical/quasi-physical paradigm and, consequently, offering additional problems of computing/robotic simulation/emulation. To shadow forth a (possible) blueprint model of (part of) such processes in which a especial emphasis is laid upon the affective and associative ones is just one of the major objectives of this paper. The model relies upon my own neuro-fuzzy approach to Pask's concept of entailment-mesh, albeit radically modified and extended and it works as an introduction to a more extended approach to the aforementioned problem of human psychodynamics.

  6. Prolene (mesh bulbourethral sling in male incontinence

    Directory of Open Access Journals (Sweden)

    Rakesh Kapoor

    2007-01-01

    Full Text Available Objective : We present our preliminary results of bulbar urethral sling (single bolster in treatment of postprostatectomy urinary incontinence (PPUI. Materials and Methods: From May 2003 to June 2005, six patients with postprostatectomy urinary incontinence (transurethral resection of prostate in five patients and after open prostatectomy in one patient underwent prolene mesh bulbar urethral sling surgery. Preoperative evaluation included physical examination, neurological assessment, stress cystogram and urethrocystoscopy. Urodynamic evaluation was done in all patients for abdominal leak point pressure and ruling out bladder pathology. Results : Urodynamic studies did not demonstrate bladder instability in any patient. Mean abdominal leak point pressure was 43cm of water (range 26-80 cm of water. Mean duration of hospital stay was 3.2 days. Follow-up ranged from 6-22 months. Four patients out of six patients were completely dry till their last follow-up. One patient developed mild stress incontinence after one year of the surgery and required use of one to two pads per day. Mean pad use after surgery was 0.6 pads per day in comparison to mean pad usage of 6.4 pads per day preoperatively. One patient was over-continent after the procedure and required clean intermittent catheterization till last follow-up (six months. Mean cost of the procedure was $ 350+15. Conclusion: Prolene bulbar urethral sling (single bolster is an economically effective option in patients with postprostatectomy urinary incontinence.

  7. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2014-02-01

    In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a distributed MAC protocol called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs. TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it receives a sufficient number of grant control messages from these neighbors. A grant message indicates that the associated data packet has the lowest timestamp of all the packets pending transmission at the local transmit queue. We demonstrate that a loose ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily integrated in existing 802.11-based WMNs. Our simulation results show that TMAC achieves excellent resource allocation fairness while maintaining over 90% of maximum link capacity across a large number of topologies.

  8. Adaptive Mesh Fluid Simulations on GPU

    CERN Document Server

    Wang, Peng; Kaehler, Ralf

    2009-01-01

    We describe an implementation of compressible inviscid fluid solvers with block-structured adaptive mesh refinement on Graphics Processing Units using NVIDIA's CUDA. We show that a class of high resolution shock capturing schemes can be mapped naturally on this architecture. Using the method of lines approach with the second order total variation diminishing Runge-Kutta time integration scheme, piecewise linear reconstruction, and a Harten-Lax-van Leer Riemann solver, we achieve an overall speedup of approximately 10 times faster execution on one graphics card as compared to a single core on the host computer. We attain this speedup in uniform grid runs as well as in problems with deep AMR hierarchies. Our framework can readily be applied to more general systems of conservation laws and extended to higher order shock capturing schemes. This is shown directly by an implementation of a magneto-hydrodynamic solver and comparing its performance to the pure hydrodynamic case. Finally, we also combined our CUDA par...

  9. Elliptic Solvers for Adaptive Mesh Refinement Grids

    Energy Technology Data Exchange (ETDEWEB)

    Quinlan, D.J.; Dendy, J.E., Jr.; Shapira, Y.

    1999-06-03

    We are developing multigrid methods that will efficiently solve elliptic problems with anisotropic and discontinuous coefficients on adaptive grids. The final product will be a library that provides for the simplified solution of such problems. This library will directly benefit the efforts of other Laboratory groups. The focus of this work is research on serial and parallel elliptic algorithms and the inclusion of our black-box multigrid techniques into this new setting. The approach applies the Los Alamos object-oriented class libraries that greatly simplify the development of serial and parallel adaptive mesh refinement applications. In the final year of this LDRD, we focused on putting the software together; in particular we completed the final AMR++ library, we wrote tutorials and manuals, and we built example applications. We implemented the Fast Adaptive Composite Grid method as the principal elliptic solver. We presented results at the Overset Grid Conference and other more AMR specific conferences. We worked on optimization of serial and parallel performance and published several papers on the details of this work. Performance remains an important issue and is the subject of continuing research work.

  10. Mesoscopic spatial designs of nano- and microfiber meshes for tissue-engineering matrix and scaffold based on newly devised multilayering and mixing electrospinning techniques.

    Science.gov (United States)

    Kidoaki, Satoru; Kwon, Il Kuen; Matsuda, Takehisa

    2005-01-01

    To design a mesoscopically ordered structure of the matrices and scaffolds composed of nano- and microscale fiber meshes for artificial and tissue-engineering devices, two new electrospinning techniques are proposed: multilayering electrospinning and mixing electrospinning. First, the following four kinds of component polymers were individually electrospun to determine the conditions for producing stable nano- and microfibers by optimizing the formulation parameters (solvent and polymer concentration) and operation parameters (voltage, air gap, and flow rate) for each polymer: (a) type I collagen, (b) styrenated gelatin (ST-gelatin), (c) segmented polyurethane (SPU), and (d) poly(ethylene oxide). A trilayered electrospun mesh, in which individual fiber meshes (type I collagen, ST-gelatin, and SPU) were deposited layer by layer, was formed by sequential electrospinning; this was clearly visualized by confocal laser scanning microscopy. The mixed electrospun-fiber mesh composed of SPU and PEO was prepared by simultaneous electrospinning on a stainless-steel mandrel with high-speed rotation and traverse movement. A bilayered tubular construct composed of a thick SPU microfiber mesh as an outer layer and a thin type I collagen nanofiber mesh as an inner layer was fabricated as a prototype scaffold of artificial grafts, and visualized by scanning electron microscopy.

  11. Receiver Based Traffic Control Mechanism to Protect Low Capacity Network in Infrastructure Based Wireless Mesh Network

    Science.gov (United States)

    Gilani, Syed Sherjeel Ahmad; Zubair, Muhammad; Khan, Zeeshan Shafi

    Infrastructure-based Wireless Mesh Networks are emerging as an affordable, robust, flexible and scalable technology. With the advent of Wireless Mesh Networks (WMNs) the dream of connecting multiple technology based networks seems to come true. A fully secure WMN is still a challenge for the researchers. In infrastructure-based WMNs almost all types of existing Wireless Networks like Wi-Fi, Cellular, WiMAX, and Sensor etc can be connected through Wireless Mesh Routers (WMRs). This situation can lead to a security problem. Some nodes can be part of the network with high processing power, large memory and least energy issues while others may belong to a network having low processing power, small memory and serious energy limitations. The later type of the nodes is very much vulnerable to targeted attacks. In our research we have suggested to set some rules on the WMR to mitigate these kinds of targeted flooding attacks. The WMR will then share those set of rules with other WMRs for Effective Utilization of Resources.

  12. DISCONTINUITY-CAPTURING FINITE ELEMENT COMPUTATION OF UNSTEADY FLOW WITH ADAPTIVE UNSTRUCTURED MESH

    Institute of Scientific and Technical Information of China (English)

    DONG Genjin; LU Xiyun; ZHUANG Lixian

    2004-01-01

    A discontinuity-capturing scheme of finite element method (FEM) is proposed. The unstructured-grid technique combined with a new type of adaptive mesh approach is developed for both compressible and incompressible unsteady flows, which exhibits the capability of capturing the shock waves and/or thin shear layers accurately in an unsteady viscous flow at high Reynolds number.In particular, a new testing variable, i.e., the disturbed kinetic energy E, is suggested and used in the adaptive mesh computation, which is universally applicable to the capturing of both shock waves and shear layers in the inviscid flow and viscous flow at high Reynolds number. Based on several calculated examples, this approach has been proved to be effective and efficient for the calculations of compressible and incompressible flows.

  13. Joint Channel Assignment and Routing in Multiradio Multichannel Wireless Mesh Networks: Design Considerations and Approaches

    Directory of Open Access Journals (Sweden)

    Omar M. Zakaria

    2016-01-01

    Full Text Available Multiradio wireless mesh network is a promising architecture that improves the network capacity by exploiting multiple radio channels concurrently. Channel assignment and routing are underlying challenges in multiradio architectures since both determine the traffic distribution over links and channels. The interdependency between channel assignments and routing promotes toward the joint solutions for efficient configurations. This paper presents an in-depth review of the joint approaches of channel assignment and routing in multiradio wireless mesh networks. First, the key design issues, modeling, and approaches are identified and discussed. Second, existing algorithms for joint channel assignment and routing are presented and classified based on the channel assignment types. Furthermore, the set of reconfiguration algorithms to adapt the network traffic dynamics is also discussed. Finally, the paper presents some multiradio practical implementations and test-beds and points out the future research directions.

  14. MeSHy: Mining unanticipated PubMed information using frequencies of occurrences and concurrences of MeSH terms.

    Science.gov (United States)

    Theodosiou, T; Vizirianakis, I S; Angelis, L; Tsaftaris, A; Darzentas, N

    2011-12-01

    PubMed is the most widely used database of biomedical literature. To the detriment of the user though, the ranking of the documents retrieved for a query is not content-based, and important semantic information in the form of assigned Medical Subject Headings (MeSH) terms is not readily presented or productively utilized. The motivation behind this work was the discovery of unanticipated information through the appropriate ranking of MeSH term pairs and, indirectly, documents. Such information can be useful in guiding novel research and following promising trends. A web-based tool, called MeSHy, was developed implementing a mainly statistical algorithm. The algorithm takes into account the frequencies of occurrences, concurrences, and the semantic similarities of MeSH terms in retrieved PubMed documents to create MeSH term pairs. These are then scored and ranked, focusing on their unexpectedly frequent or infrequent occurrences. MeSHy presents results through an online interactive interface facilitating further manipulation through filtering and sorting. The results themselves include the MeSH term pairs, along with MeSH categories, the score, and document IDs, all of which are hyperlinked for convenience. To highlight the applicability of the tool, we report the findings of an expert in the pharmacology field on querying the molecularly-targeted drug imatinib and nutrition-related flavonoids. To the best of our knowledge, MeSHy is the first publicly available tool able to directly provide such a different perspective on the complex nature of published work. Implemented in Perl and served by Apache2 at http://bat.ina.certh.gr/tools/meshy/ with all major browsers supported. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Performance of the hybrid wireless mesh protocol for wireless mesh networks

    DEFF Research Database (Denmark)

    Boye, Magnus; Staalhagen, Lars

    2010-01-01

    . These challenges must first be overcome before satisfactory network stability and throughput can be achieved. This paper studies the performance of the Hybrid Wireless Mesh Protocol, the proposed routing protocol for the upcoming IEEE 802.11s standard. HWMP supports two modes of path selection: reactive...... and proactive. Two scenarios of different node density are considered for both path selection modes. The results presented in this paper are based on a simulation model of the HWMP specification in the IEEE 802.11s draft 4.0 implemented in OPNET Modeler....

  16. GeneMesh: a web-based microarray analysis tool for relating differentially expressed genes to MeSH terms

    Directory of Open Access Journals (Sweden)

    Argraves W Scott

    2010-04-01

    Full Text Available Abstract Background An important objective of DNA microarray-based gene expression experimentation is determining inter-relationships that exist between differentially expressed genes and biological processes, molecular functions, cellular components, signaling pathways, physiologic processes and diseases. Results Here we describe GeneMesh, a web-based program that facilitates analysis of DNA microarray gene expression data. GeneMesh relates genes in a query set to categories available in the Medical Subject Headings (MeSH hierarchical index. The interface enables hypothesis driven relational analysis to a specific MeSH subcategory (e.g., Cardiovascular System, Genetic Processes, Immune System Diseases etc. or unbiased relational analysis to broader MeSH categories (e.g., Anatomy, Biological Sciences, Disease etc.. Genes found associated with a given MeSH category are dynamically linked to facilitate tabular and graphical depiction of Entrez Gene information, Gene Ontology information, KEGG metabolic pathway diagrams and intermolecular interaction information. Expression intensity values of groups of genes that cluster in relation to a given MeSH category, gene ontology or pathway can be displayed as heat maps of Z score-normalized values. GeneMesh operates on gene expression data derived from a number of commercial microarray platforms including Affymetrix, Agilent and Illumina. Conclusions GeneMesh is a versatile web-based tool for testing and developing new hypotheses through relating genes in a query set (e.g., differentially expressed genes from a DNA microarray experiment to descriptors making up the hierarchical structure of the National Library of Medicine controlled vocabulary thesaurus, MeSH. The system further enhances the discovery process by providing links between sets of genes associated with a given MeSH category to a rich set of html linked tabular and graphic information including Entrez Gene summaries, gene ontologies

  17. A LAGUERRE VORONOI BASED SCHEME FOR MESHING PARTICLE SYSTEMS.

    Science.gov (United States)

    Bajaj, Chandrajit

    2005-06-01

    We present Laguerre Voronoi based subdivision algorithms for the quadrilateral and hexahedral meshing of particle systems within a bounded region in two and three dimensions, respectively. Particles are smooth functions over circular or spherical domains. The algorithm first breaks the bounded region containing the particles into Voronoi cells that are then subsequently decomposed into an initial quadrilateral or an initial hexahedral scaffold conforming to individual particles. The scaffolds are subsequently refined via applications of recursive subdivision (splitting and averaging rules). Our choice of averaging rules yield a particle conforming quadrilateral/hexahedral mesh, of good quality, along with being smooth and differentiable in the limit. Extensions of the basic scheme to dynamic re-meshing in the case of addition, deletion, and moving particles are also discussed. Motivating applications of the use of these static and dynamic meshes for particle systems include the mechanics of epoxy/glass composite materials, bio-molecular force field calculations, and gas hydrodynamics simulations in cosmology.

  18. RSW Mixed Element Cell-Centered Medium Mesh

    Data.gov (United States)

    National Aeronautics and Space Administration — This RSW gridset is designed as the medium size mixed element grid for use with cell-centered unstructured meshes. UG3 : Grid File Name = rsw_med_mixedcc.b8.ugrid...

  19. Laparoscopic mesh repair of parahiatal hernia: a case report.

    Science.gov (United States)

    Lew, Pei Shi; Wong, Andrew Siang Yih

    2013-08-01

    We report a case of a primary parahiatal hernia that was repaired laparoscopically with a composite mesh. A 51-year-old woman presented with vomiting and epigastric pain. CT scan showed a giant paraesophageal hernia with intrathoracic gastric volvulus. Intraoperatively, a diaphragmatic muscular defect was found lateral to an attenuated left crus of the diaphragm, distinct from the normal esophageal hiatus. The defect ring was fibrotic, making a tension-free primary repair difficult. A laparoscopic mesh repair was performed with a composite mesh, which was covered with the hernia sac to prevent potential erosion into the esophagus or stomach. Recovery was uneventful and the patient was discharged on the 5 days postoperatively. She remained asymptomatic at subsequent follow-up. Laparoscopic repair of parahiatal hernia can be safely performed. In circumstances where a large or fibrotic defect prevents a tension-free primary repair, the use of a composite mesh can provide effective repair of the hernia.

  20. Form-finding with polyhedral meshes made simple

    KAUST Repository

    Tang, Chengcheng

    2014-07-27

    We solve the form-finding problem for polyhedral meshes in a way which combines form, function and fabrication; taking care of user-specified constraints like boundary interpolation, planarity of faces, statics, panel size and shape, enclosed volume, and last, but not least, cost. Our main application is the interactive modeling of meshes for architectural and industrial design. Our approach can be described as guided exploration of the constraint space whose algebraic structure is simplified by introducing auxiliary variables and ensuring that constraints are at most quadratic. Computationally, we perform a projection onto the constraint space which is biased towards low values of an energy which expresses desirable "soft" properties like fairness. We have created a tool which elegantly handles difficult tasks, such as taking boundary-alignment of polyhedral meshes into account, planarization, fairing under planarity side conditions, handling hybrid meshes, and extending the treatment of static equilibrium to shapes which possess overhanging parts.

  1. On Optimizing Gateway Placement for Throughput in Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Wang Xudong

    2010-01-01

    Full Text Available An innovative gateway placement scheme is proposed for wireless mesh networks (WMNs in this paper. It determines the location of a gateway based on a new performance metric called multihop traffic-flow weight (MTW. The MTW computation takes into account many factors that impact the throughput of WMNs, that is, the number of mesh routers, the number of mesh clients, the number of gateways, traffic demand from mesh clients, locations of gateways, and possible interference among gateways. Thus, the proposed gateway placement scheme provides a framework of significantly improving throughput of WMNs through proper placement of gateways. To evaluate the performance of the new gateway placement scheme, a nonasymptotic throughput of WMNs is derived by considering TDMA scheduling. The derivations also provide a guideline for designing scheduling schemes of WMNs. Numeric results show that the proposed gateway placement scheme constantly outperforms other schemes by a large margin.

  2. RSW Fully Tet Coarse Cell-Centered Mesh

    Data.gov (United States)

    National Aeronautics and Space Administration — This is the RSW fully tetrahedral unstructured mesh dataset for a cell-centered code, including the viscous wind tunnel wall. UG3 : Grid File Name =...

  3. Efficient Minimum Spanning Tree Algorithms on the Reconfigurable Mesh

    Institute of Scientific and Technical Information of China (English)

    万颖瑜; 许胤龙; 顾晓东; 陈国良

    2000-01-01

    he reconfigurable mesh consists of an array of processors interconnected by a reconfigurable bus system. The bus system can be used to dynamically obtain various interconnection patterns among the processors. Recently, this model has attracted a lot of attention. In this paper, two efficient algorithms are proposed for computing the minimum spanning tree of an n-vertex undirected graph. One runs on an n×n reconfigurable mesh with time complexity of O(log2 n). The other runs with time complexity of O(log n) on an n1+ε×n reconfigurable mesh, where 0 < e < I is a constant. All these improve the previously known results on the reconfigurable mesh.

  4. Quality Tetrahedral Mesh Smoothing via Boundary-Optimized Delaunay Triangulation.

    Science.gov (United States)

    Gao, Zhanheng; Yu, Zeyun; Holst, Michael

    2012-12-01

    Despite its great success in improving the quality of a tetrahedral mesh, the original optimal Delaunay triangulation (ODT) is designed to move only inner vertices and thus cannot handle input meshes containing "bad" triangles on boundaries. In the current work, we present an integrated approach called boundary-optimized Delaunay triangulation (B-ODT) to smooth (improve) a tetrahedral mesh. In our method, both inner and boundary vertices are repositioned by analytically minimizing the error between a paraboloid function and its piecewise linear interpolation over the neighborhood of each vertex. In addition to the guaranteed volume-preserving property, the proposed algorithm can be readily adapted to preserve sharp features in the original mesh. A number of experiments are included to demonstrate the performance of our method.

  5. Planet-disc interaction on a freely moving mesh

    CERN Document Server

    Munoz, Diego J; Springel, Volker; Hernquist, Lars

    2014-01-01

    General-purpose, moving-mesh schemes for hydrodynamics have opened the possibility of combining the accuracy of grid-based numerical methods with the flexibility and automatic resolution adaptivity of particle-based methods. Due to their supersonic nature, Keplerian accretion discs are in principle a very attractive system for applying such freely moving mesh techniques. However, the high degree of symmetry of simple accretion disc models can be difficult to capture accurately by these methods, due to the generation of geometric grid noise and associated numerical diffusion, which is absent in polar grids. To explore these and other issues, in this work we study the idealized problem of two-dimensional planet-disc interaction with the moving-mesh code AREPO. We explore the hydrodynamic evolution of discs with planets through a series of numerical experiments that vary the planet mass, the disc viscosity and the mesh resolution, and compare the resulting surface density, vortensity field and tidal torque with ...

  6. Integrated analysis system for box truss antenna mesh performance

    Science.gov (United States)

    Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.

    1986-01-01

    An integrated analysis system has been developed to more efficiently design and analyze the mesh reflective surface and the mesh tie system of the box truss antenna. Six integrated computer programs using nonlinear finite-element, surface topography and interpolation, and RF aperture integration techniques, analyze the effects of manufacturing errors, mesh pillowing, and operating environment on antenna performance. The level of rigor of analysis can be varied, providing the possibility of a lower cost preliminary study on various designs using a minimum number of reduced box section models. By including the random and systematic errors with the aperture integration of minimum rms reflector surface roughness, the RF Performance Solver determines the far-field pattern, including the beam efficiency, and thus the antenna performance of the mesh reflector antenna.

  7. 28 Comparative Study of Open Mesh Repair and Desarda's No ...

    African Journals Online (AJOL)

    user

    2006-12-02

    Dec 2, 2006 ... East And Central African Journal of Surgery Volume 11 Number 2. ... new technique and the open mesh repair done in a district level general hospital set ... laparoscopic repairs or the patients given ..... Hernia repair (Open Vs.

  8. On the Support of Multimedia Applications over Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    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.

  9. The use of mesh implants in vaginal prolapse surgery: Position ...

    African Journals Online (AJOL)

    the risks and benefits of surgery with mesh versus all surgical and non-surgical alternatives'. ... Johnson) or partially (Boston Scientific, CR Bard) from the market, and anecdotally the .... sacrocolpopexy (open or endoscopic). • Complications ...

  10. Application-specific mesh-based heterogeneous FPGA architectures

    CERN Document Server

    Parvez, Husain

    2011-01-01

    This volume presents a new exploration environment for mesh-based, heterogeneous FPGA architectures. Readers will find a description of state-of-the-art techniques for reducing area requirements, which both increase performance and enable power reduction.

  11. Design and Implementation of the MESH Services Platform

    NARCIS (Netherlands)

    Batteram, Harold J.; Bakker, John-Luc; Verhoosel, Jack P.C.; Diakov, Nikolay K.

    1999-01-01

    Industry acceptance of TINA (Telecommunications Information Networking Architecture) will depend heavily on both the evaluation of working systems that implement this architecture, and on the experiences obtained during the design and implementation of these systems. During the MESH' (Multimedia ser

  12. Mechanical durability of superhydrophobic and oleophobic copper meshes

    Science.gov (United States)

    Yin, Linting; Yang, Jin; Tang, Yongcai; Chen, Lin; Liu, Can; Tang, Hua; Li, Changsheng

    2014-10-01

    We developed a simple and inexpensive method to prepare the superhydrophobic and oleophobic copper meshes with rough structures fabrication and chemical modification. The achieved surfaces displayed liquid-repellent toward water and several organic liquids (such as hexadecane), which possessed much lower surface tension than that of water. Liquid repellency of the fabricated superhydrophobic copper mesh was demonstrated by visible experiment results and contact angle measurements. Even if the superhydrophobic copper mesh was rolled up, it still kept the superhydrophobicity. The mechanical durability was investigated by finger touch and mechanical abrasion tests. The results indicated that the copper mesh can maintain its superhydrophobicity against an abrasion length of 300 cm under a high pressure (77.2 kPa). The superhydrophobicity and oleophobicity, combined with mechanical durability, would promote the superhydrophobic surface to practical application in industry in the future.

  13. Constructing C1 Continuous Surface on Irregular Quad Meshes

    Institute of Scientific and Technical Information of China (English)

    HE Jun; GUO Qiang

    2013-01-01

    A new method is proposed for surface construction on irregular quad meshes as extensions to uniform B-spline surfaces. Given a number of control points, which form a regular or irregular quad mesh, a weight function is constructed for each control point. The weight function is defined on a local domain and is C1 continuous. Then the whole surface is constructed by the weighted combination of all the control points. The property of the new method is that the surface is defined by piecewise C1 bi-cubic rational parametric polynomial with each quad face. It is an extension to uniform B-spline surfaces in the sense that its definition is an analogy of the B-spline surface, and it produces a uniform bi-cubic B-spline surface if the control mesh is a regular quad mesh. Examples produced by the new method are also included.

  14. Design methodology of the strength properties of medical knitted meshes

    Science.gov (United States)

    Mikołajczyk, Z.; Walkowska, A.

    2016-07-01

    One of the most important utility properties of medical knitted meshes intended for hernia and urological treatment is their bidirectional strength along the courses and wales. The value of this parameter, expected by the manufacturers and surgeons, is estimated at 100 N per 5 cm of the sample width. The most frequently, these meshes are produced on the basis of single- or double-guide stitches. They are made of polypropylene and polyester monofilament yarns with the diameter in the range from 0.6 to 1.2 mm, characterized by a high medical purity. The aim of the study was to develop the design methodology of meshes strength based on the geometrical construction of the stitch and strength of yarn. In the environment of the ProCAD warpknit 5 software the simulated stretching process of meshes together with an analysis of their geometry changes was carried out. Simulations were made for four selected representative stitches. Both on a built, unique measuring position and on the tensile testing machine the real parameters of the loops geometry of meshes were measured. Model of mechanical stretching of warp-knitted meshes along the courses and wales was developed. The thesis argument was made, that the force that breaks the loop of warp-knitted fabric is the lowest value of breaking forces of loop link yarns or yarns that create straight sections of loop. This thesis was associate with the theory of strength that uses the “the weakest link concept”. Experimental verification of model was carried out for the basic structure of the single-guide mesh. It has been shown that the real, relative strength of the mesh related to one course is equal to the strength of the yarn breakage in a loop, while the strength along the wales is close to breaking strength of a single yarn. In relation to the specific construction of the medical mesh, based on the knowledge of the density of the loops structure, the a-jour mesh geometry and the yarns strength, it is possible, with high

  15. Finite element meshing approached as a global minimization process

    Energy Technology Data Exchange (ETDEWEB)

    WITKOWSKI,WALTER R.; JUNG,JOSEPH; DOHRMANN,CLARK R.; LEUNG,VITUS J.

    2000-03-01

    The ability to generate a suitable finite element mesh in an automatic fashion is becoming the key to being able to automate the entire engineering analysis process. However, placing an all-hexahedron mesh in a general three-dimensional body continues to be an elusive goal. The approach investigated in this research is fundamentally different from any other that is known of by the authors. A physical analogy viewpoint is used to formulate the actual meshing problem which constructs a global mathematical description of the problem. The analogy used was that of minimizing the electrical potential of a system charged particles within a charged domain. The particles in the presented analogy represent duals to mesh elements (i.e., quads or hexes). Particle movement is governed by a mathematical functional which accounts for inter-particles repulsive, attractive and alignment forces. This functional is minimized to find the optimal location and orientation of each particle. After the particles are connected a mesh can be easily resolved. The mathematical description for this problem is as easy to formulate in three-dimensions as it is in two- or one-dimensions. The meshing algorithm was developed within CoMeT. It can solve the two-dimensional meshing problem for convex and concave geometries in a purely automated fashion. Investigation of the robustness of the technique has shown a success rate of approximately 99% for the two-dimensional geometries tested. Run times to mesh a 100 element complex geometry were typically in the 10 minute range. Efficiency of the technique is still an issue that needs to be addressed. Performance is an issue that is critical for most engineers generating meshes. It was not for this project. The primary focus of this work was to investigate and evaluate a meshing algorithm/philosophy with efficiency issues being secondary. The algorithm was also extended to mesh three-dimensional geometries. Unfortunately, only simple geometries were tested

  16. Fibrin sealant for mesh fixation in laparoscopic umbilical hernia repair

    DEFF Research Database (Denmark)

    Eriksen, J R; Bisgaard, T; Assaadzadeh, S;

    2013-01-01

    Fibrin sealant for mesh fixation has significant positive effects on early outcome after laparoscopic ventral hernia repair (LVHR) compared with titanium tacks. Whether fibrin sealant fixation also results in better long-term outcome is unknown.......Fibrin sealant for mesh fixation has significant positive effects on early outcome after laparoscopic ventral hernia repair (LVHR) compared with titanium tacks. Whether fibrin sealant fixation also results in better long-term outcome is unknown....

  17. GENERATION AND APPLICATION OF UNSTRUCTURED ADAPTIVE MESHES WITH MOVING BOUNDARIES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents a method to generate unstructured adaptive meshes with moving boundaries and its application to CFD. Delaunay triangulation criterion in conjunction with the automatic point creation is used to generate 2-D and 3-D unstructured grids. A local grid regeneration method is proposed to cope with moving boundaries. Numerical examples include the interactions of shock waves with movable bodies and the movement of a projectile within a ram accelerator, illustrating an efficient and robust mesh generation method developed.``

  18. A general boundary capability embedded in an orthogonal mesh

    Energy Technology Data Exchange (ETDEWEB)

    Hewett, D.W.; Yu-Jiuan Chen [Lawrence Livermore National Lab., CA (United States)

    1995-07-01

    The authors describe how they hold onto orthogonal mesh discretization when dealing with curved boundaries. Special difference operators were constructed to approximate numerical zones split by the domain boundary; the operators are particularly simple for this rectangular mesh. The authors demonstrated that this simple numerical approach, termed Dynamic Alternating Direction Implicit, turned out to be considerably more efficient than more complex grid-adaptive algorithms that were tried previously.

  19. Feedforward Control of Gear Mesh Vibration Using Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Gerald T. Montague

    1994-01-01

    Full Text Available This article presents a novel means for suppressing gear mesh related vibrations. The key components in this approach are piezoelectric actuators and a high-frequency, analog feed forward controller. Test results are presented and show up to a 70% reduction in gear mesh acceleration and vibration control up to 4500 Hz. The principle of the approach is explained by an analysis of a harmonically excited, general linear vibratory system.

  20. Viscous flow modelling using unstructured meshes for aeronautical applications

    Science.gov (United States)

    Szmelter, J.; Pagano, A.

    The novel application of viscous coupling to unstructured meshes has been proposed and developed. The method allows fro viscous flows modelling and avoids the difficulty of generating highly stretched tetrahedral in 3D or triangular in 2D elements required for Navier-Stokes solvers. The time step allowed by the explicit euler solver is limited by the size of the "Euler" mesh, resulting in faster algorithms than standard explicit Navier-Stokes solvers.

  1. Engagement of Metal Debris into a Gear Mesh

    Science.gov (United States)

    Handschuh, Robert F.; Krantz, Timothy L.

    2009-01-01

    A series of bench top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock, and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined. INTRODUCTION In some space mechanisms the loading can be so high that there is some possibility that a gear chip might be liberated while in operation of the mechanism [1-5]. Also, due to the closely packed nature of some space mechanisms and the fact that a space grease is used for lubrication, chips that are released can then be introduced to other gear meshes within this mechanism. In this instance, it is desirable to know the consequences of a gear chip entering in between meshing gear teeth. To help provide some understanding, a series of bench-top experiments was conducted to engage chips of simulated and gear material fragments into a meshing gear pair. One purpose of the experiments was to determine the relationship of chip size to the torque required to rotate the gear set through the mesh cycle. The second purpose was to determine the condition of the gear chip material after engagement by the meshing gears, primarily to determine if the chip would break into pieces and to observe the motion of the chip as the engagement was completed. This document also presents preliminary testing done with metal debris other than chips from gears, namely steel shim stock and drill bits of various sizes and diameters.

  2. Overlap Areas of a Square Box on a Square Mesh

    Science.gov (United States)

    2017-04-01

    ARL-TN-0818 ● APR 2017 US Army Research Laboratory Overlap Areas of a Square Box on a Square Mesh by James U Cazamias...originator. ARL-TN-0818 ● APR 2017 US Army Research Laboratory Overlap Areas of a Square Box on a Square Mesh by James U Cazamias...no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control

  3. First tests of "bulk" MICROMEGAS with resistive cathode mesh

    CERN Document Server

    Olivera, R; Pietropaolo, F; Picchi, P

    2010-01-01

    We present the first results from tests of a MICROMEGAS detector manufactured using the so-called "bulk" technology and having a resistive cathode mesh instead of the conventional metallic one. This detector operates as usual MICROMEGAS, but in the case of sparks, which may appear at high gas gains, the resistive mesh reduces their current and makes the sparks harmless. This approach could be complementary to the ongoing efforts of various groups to develop spark-protected MICROMEGAS with resistive anode planes.

  4. Reconstructive laparoscopic prolapse surgery to avoid mesh erosions

    Directory of Open Access Journals (Sweden)

    Devassy, Rajesh

    2013-09-01

    Full Text Available Introduction: The objective of the study is to examine the efficacy of the purely laparoscopic reconstructive management of cystocele and rectocele with mesh, to avoid the risk of erosion by the graft material, a well known complication in vaginal mesh surgery. Material and methods: We performed a prospective, single-case, non-randomized study in 325 patients who received laparoscopic reconstructive management of pelvic organe prolaps with mesh. The study was conducted between January 2004 and December 2012 in a private clinic in India. The most common prolapse symptoms were reducible vaginal lump, urinary stress incontinence, constipation and flatus incontinence, sexual dysfunction and dypareunia. The degree e of the prolaps was staged according to POPQ system. The approach was purely laparoscopic and involved the use of polypropylene (Prolene or polyurethane with activated regenerated cellulose coating (Parietex mesh. Results: The mean age was 55 (30–80 years and the most of the patients were multiparous (272/325. The patients received a plastic correction of the rectocele only (138 cases, a cystocele and rectocele (187 cases with mesh. 132 patients had a concomitant total hysterectomy; in 2 cases a laparoscopic supracervical hysterectomy was performed and 190 patients had a laparoscopic colposuspension. The mean operation time was 82.2 (60–210 minutes. The mean follow up was 3.4 (3–5 years. Urinary retention developed in 1 case, which required a new laparoscopical intervention. Bladder injury, observed in the same case was in one session closed with absorbable suture. There were four recurrences of the rectocele, receiving a posterior vaginal colporrhaphy. Erosions of the mesh were not reported or documented. Conclusion: The pure laparoscopic reconstructive management of the cystocele and rectocele with mesh seems to be a safe and effective surgical procedure potentially avoiding the risk of mesh erosions.

  5. Adaptive mesh generation for viscous flows using Delaunay triangulation

    Science.gov (United States)

    Mavriplis, Dimitri J.

    1990-01-01

    A method for generating an unstructured triangular mesh in two dimensions, suitable for computing high Reynolds number flows over arbitrary configurations is presented. The method is based on a Delaunay triangulation, which is performed in a locally stretched space, in order to obtain very high aspect ratio triangles in the boundary layer and the wake regions. It is shown how the method can be coupled with an unstructured Navier-Stokes solver to produce a solution adaptive mesh generation procedure for viscous flows.

  6. Tangle-Free Mesh Motion for Ablation Simulations

    Science.gov (United States)

    Droba, Justin

    2016-01-01

    Problems involving mesh motion-which should not be mistakenly associated with moving mesh methods, a class of adaptive mesh redistribution techniques-are of critical importance in numerical simulations of the thermal response of melting and ablative materials. Ablation is the process by which material vaporizes or otherwise erodes due to strong heating. Accurate modeling of such materials is of the utmost importance in design of passive thermal protection systems ("heatshields") for spacecraft, the layer of the vehicle that ensures survival of crew and craft during re-entry. In an explicit mesh motion approach, a complete thermal solve is first performed. Afterwards, the thermal response is used to determine surface recession rates. These values are then used to generate boundary conditions for an a posteriori correction designed to update the location of the mesh nodes. Most often, linear elastic or biharmonic equations are used to model this material response, traditionally in a finite element framework so that complex geometries can be simulated. A simple scheme for moving the boundary nodes involves receding along the surface normals. However, for all but the simplest problem geometries, evolution in time following such a scheme will eventually bring the mesh to intersect and "tangle" with itself, inducing failure. This presentation demonstrates a comprehensive and sophisticated scheme that analyzes the local geometry of each node with help from user-provided clues to eliminate the tangle and enable simulations on a wide-class of difficult problem geometries. The method developed is demonstrated for linear elastic equations but is general enough that it may be adapted to other modeling equations. The presentation will explicate the inner workings of the tangle-free mesh motion algorithm for both two and three-dimensional meshes. It will show abstract examples of the method's success, including a verification problem that demonstrates its accuracy and

  7. Generation of Triangular Meshes for Complex Domains on the Plane

    OpenAIRE

    Barbara Glut; Tomasz Jurczyk

    2001-01-01

    Many physical phenomena can be modeled by partial differential equations. The development of numerical methods based on the spatial subdivision of a domain into finite elements immediately extended interests to the tasks of generating a mesh. With the availability of versatile field solvers and powerful computers, the simulations of ever incrcasing geometrical and physical complexity are attempted. At some point the main bottleneck becomes the mesh generation itself. The paper presents a deta...

  8. An application of MeSH enrichment analysis in livestock.

    Science.gov (United States)

    Morota, G; Peñagaricano, F; Petersen, J L; Ciobanu, D C; Tsuyuzaki, K; Nikaido, I

    2015-08-01

    An integral part of functional genomics studies is to assess the enrichment of specific biological terms in lists of genes found to be playing an important role in biological phenomena. Contrasting the observed frequency of annotated terms with those of the background is at the core of overrepresentation analysis (ORA). Gene Ontology (GO) is a means to consistently classify and annotate gene products and has become a mainstay in ORA. Alternatively, Medical Subject Headings (MeSH) offers a comprehensive life science vocabulary including additional categories that are not covered by GO. Although MeSH is applied predominantly in human and model organism research, its full potential in livestock genetics is yet to be explored. In this study, MeSH ORA was evaluated to discern biological properties of identified genes and contrast them with the results obtained from GO enrichment analysis. Three published datasets were employed for this purpose, representing a gene expression study in dairy cattle, the use of SNPs for genome-wide prediction in swine and the identification of genomic regions targeted by selection in horses. We found that several overrepresented MeSH annotations linked to these gene sets share similar concepts with those of GO terms. Moreover, MeSH yielded unique annotations, which are not directly provided by GO terms, suggesting that MeSH has the potential to refine and enrich the representation of biological knowledge. We demonstrated that MeSH can be regarded as another choice of annotation to draw biological inferences from genes identified via experimental analyses. When used in combination with GO terms, our results indicate that MeSH can enhance our functional interpretations for specific biological conditions or the genetic basis of complex traits in livestock species.

  9. Impact of document type on reporting quality of clinical drug trials: a comparison of registry reports, clinical study reports, and journal publications.

    Science.gov (United States)

    Wieseler, Beate; Kerekes, Michaela F; Vervoelgyi, Volker; McGauran, Natalie; Kaiser, Thomas

    2012-01-03

    To investigate to what extent three types of documents for reporting clinical trials provide sufficient information for trial evaluation. Retrospective analysis Primary studies and corresponding documents (registry reports, clinical study reports, journal publications) from 16 health technology assessments of drugs conducted by the German Institute for Quality and Efficiency in Health Care between 2006 and February 2011. Data analysis We assessed reporting quality for each study and each available document for six items on methods and six on outcomes, and dichotomised them as "completely reported" or "incompletely reported." For each document type, we calculated the proportion of studies with complete reporting for methods and outcomes, per item and overall, and compared the findings. We identified 268 studies. Publications, study reports and registry reports were available for 192 (72%), 101 (38%), and 78 (29%) studies, respectively. Reporting quality was highest in study reports, which overall provided complete information for 90% of items (1086/1212). Registry reports provided more complete information on outcomes than on methods (overall 330/468 (71%) v 147/468 (31%)); the same applied to publications (594/1152 (52%) v 458/1152 (40%)). In the matched pairs analysis, reporting quality was poorer in registry reports than in study reports for overall methods and outcomes (P<0.001 in each case). Compared with publications, reporting quality was poorer in registry reports for overall methods (P<0.001), but better for outcomes (P=0.005). Registry reports and publications insufficiently report clinical trials but may supplement each other. Measures to improve reporting include the mandatory worldwide implementation of adequate standards for results registration.

  10. Biomimetic collagen/elastin meshes for ventral hernia repair in a rat model.

    Science.gov (United States)

    Minardi, Silvia; Taraballi, Francesca; Wang, Xin; Cabrera, Fernando J; Van Eps, Jeffrey L; Robbins, Andrew B; Sandri, Monica; Moreno, Michael R; Weiner, Bradley K; Tasciotti, Ennio

    2017-03-01

    Ventral hernia repair remains a major clinical need. Herein, we formulated a type I collagen/elastin crosslinked blend (CollE) for the fabrication of biomimetic meshes for ventral hernia repair. To evaluate the effect of architecture on the performance of the implants, CollE was formulated both as flat sheets (CollE Sheets) and porous scaffolds (CollE Scaffolds). The morphology, hydrophylicity and in vitro degradation were assessed by SEM, water contact angle and differential scanning calorimetry, respectively. The stiffness of the meshes was determined using a constant stretch rate uniaxial tensile test, and compared to that of native tissue. CollE Sheets and Scaffolds were tested in vitro with human bone marrow-derived mesenchymal stem cells (h-BM-MSC), and finally implanted in a rat ventral hernia model. Neovascularization and tissue regeneration within the implants was evaluated at 6weeks, by histology, immunofluorescence, and q-PCR. It was found that CollE Sheets and Scaffolds were not only biomechanically sturdy enough to provide immediate repair of the hernia defect, but also promoted tissue restoration in only 6weeks. In fact, the presence of elastin enhanced the neovascularization in both sheets and scaffolds. Overall, CollE Scaffolds displayed mechanical properties more closely resembling those of native tissue, and induced higher gene expression of the entire marker genes tested, associated with de novo matrix deposition, angiogenesis, adipogenesis and skeletal muscles, compared to CollE Sheets. Altogether, this data suggests that the improved mechanical properties and bioactivity of CollE Sheets and Scaffolds make them valuable candidates for applications of ventral hernia repair. Due to the elevated annual number of ventral hernia repair in the US, the lack of successful grafts, the design of innovative biomimetic meshes has become a prime focus in tissue engineering, to promote the repair of the abdominal wall, avoid recurrence. Our meshes (Coll

  11. An Implementation and Parallelization of the Scale Space Meshing Algorithm

    Directory of Open Access Journals (Sweden)

    Julie Digne

    2015-11-01

    Full Text Available Creating an interpolating mesh from an unorganized set of oriented points is a difficult problemwhich is often overlooked. Most methods focus indeed on building a watertight smoothed meshby defining some function whose zero level set is the surface of the object. However in some casesit is crucial to build a mesh that interpolates the points and does not fill the acquisition holes:either because the data are sparse and trying to fill the holes would create spurious artifactsor because the goal is to explore visually the data exactly as they were acquired without anysmoothing process. In this paper we detail a parallel implementation of the Scale-Space Meshingalgorithm, which builds on the scale-space framework for reconstructing a high precision meshfrom an input oriented point set. This algorithm first smoothes the point set, producing asingularity free shape. It then uses a standard mesh reconstruction technique, the Ball PivotingAlgorithm, to build a mesh from the smoothed point set. The final step consists in back-projecting the mesh built on the smoothed positions onto the original point set. The result ofthis process is an interpolating, hole-preserving surface mesh reconstruction.

  12. Semi-structured meshes for axial turbomachinery blades

    Science.gov (United States)

    Sbardella, L.; Sayma, A. I.; Imregun, M.

    2000-03-01

    This paper describes the development and application of a novel mesh generator for the flow analysis of turbomachinery blades. The proposed method uses a combination of structured and unstructured meshes, the former in the radial direction and the latter in the axial and tangential directions, in order to exploit the fact that blade-like structures are not strongly three-dimensional since the radial variation is usually small. The proposed semi-structured mesh formulation was found to have a number of advantages over its structured counterparts. There is a significant improvement in the smoothness of the grid spacing and also in capturing particular aspects of the blade passage geometry. It was also found that the leading- and trailing-edge regions could be discretized without generating superfluous points in the far field, and that further refinements of the mesh to capture wake and shock effects were relatively easy to implement. The capability of the method is demonstrated in the case of a transonic fan blade for which the steady state flow is predicted using both structured and semi-structured meshes. A totally unstructured mesh is also generated for the same geometry to illustrate the disadvantages of using such an approach for turbomachinery blades. Copyright

  13. Automatic Mesh Generation on a Regular Background Grid

    Institute of Scientific and Technical Information of China (English)

    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.

  14. Adaptive mesh refinement for shocks and material interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dai, William Wenlong [Los Alamos National Laboratory

    2010-01-01

    There are three kinds of adaptive mesh refinement (AMR) in structured meshes. Block-based AMR sometimes over refines meshes. Cell-based AMR treats cells cell by cell and thus loses the advantage of the nature of structured meshes. Patch-based AMR is intended to combine advantages of block- and cell-based AMR, i.e., the nature of structured meshes and sharp regions of refinement. But, patch-based AMR has its own difficulties. For example, patch-based AMR typically cannot preserve symmetries of physics problems. In this paper, we will present an approach for a patch-based AMR for hydrodynamics simulations. The approach consists of clustering, symmetry preserving, mesh continuity, flux correction, communications, management of patches, and load balance. The special features of this patch-based AMR include symmetry preserving, efficiency of refinement across shock fronts and material interfaces, special implementation of flux correction, and patch management in parallel computing environments. To demonstrate the capability of the AMR framework, we will show both two- and three-dimensional hydrodynamics simulations with many levels of refinement.

  15. Cellulose Nanofibre Mesh for Use in Dental Materials

    Directory of Open Access Journals (Sweden)

    Anthony J. Ireland

    2012-07-01

    Full Text Available The aim of this study was to produce a 3D mesh of defect free electrospun cellulose acetate nanofibres and to use this to produce a prototype composite resin containing nanofibre fillers. This might find use as an aesthetic orthodontic bracket material or composite veneer for restorative dentistry. In this laboratory based study cellulose acetate was dissolved in an acetone and dimethylacetamide solvent solution and electrospun. The spinning parameters were optimised and lithium chloride added to the solution to produce a self supporting nanofibre mesh. This mesh was then silane coated and infiltrated with either epoxy resin or an unfilled Bis-GMA resin. The flexural strength of the produced samples was measured and compared to that of unfilled resin samples. Using this method cellulose acetate nanofibres were successfully electrospun in the 286 nm range. However, resin infiltration of this mesh resulted in samples with a flexural strength less than that of the unfilled control samples. Air inclusion during preparation and incomplete wetting of the nanofibre mesh was thought to cause this reduction in flexural strength. Further work is required to reduce the air inclusions before the true effect of resin reinforcement with a 3D mesh of cellulose acetate nanofibres can be determined.

  16. Generation of Triangular Meshes for Complex Domains on the Plane

    Directory of Open Access Journals (Sweden)

    Barbara Glut

    2001-01-01

    Full Text Available Many physical phenomena can be modeled by partial differential equations. The development of numerical methods based on the spatial subdivision of a domain into finite elements immediately extended interests to the tasks of generating a mesh. With the availability of versatile field solvers and powerful computers, the simulations of ever incrcasing geometrical and physical complexity are attempted. At some point the main bottleneck becomes the mesh generation itself. The paper presents a detailed description of the triangular mesh generation scheme on the plane based upon the Delaunay triangulation. A mesh generator should be fully automatic and simplify input data as much as possible. It should offer rapid gradation from small to large sizes of elements. The generated mesh must be always valid and of good quality. All these requirements were taken into account during the selection and elaboration of utilized algorithms. Successive chapters describe procedures connected with the specification of a modeled domain, generation and triangulation of boundary vertices, introducing inner nodes, improving the quality of the created mesh, and renumbering of vertices.

  17. Initial outcomes of laparoscopic paraesophageal hiatal hernia repair with mesh.

    Science.gov (United States)

    Gebhart, Alana; Vu, Steven; Armstrong, Chris; Smith, Brian R; Nguyen, Ninh T

    2013-10-01

    The use of mesh in laparoscopic paraesophageal hiatal hernia repair (LHR) may reduce the risk of late hernia recurrence. The aim of this study was to evaluate initial outcomes and recurrence rate of 92 patients who underwent LHR reinforced with a synthetic bioabsorbable mesh. Surgical approaches included LHR and Nissen fundoplication (n = 64), LHR without fundoplication (n = 10), reoperative LHR (n = 9), LHR with a bariatric operation (n = 6), and emergent LHR (n = 3). The mean length of hospital stay was 2 ± 3 days (range, 1 to 30 days). There were no conversions to open laparotomy and no intraoperative complications. One of 92 patients (1.1%) required intensive care unit stay. The 90-day mortality was zero. Minor complications occurred in 3.3 per cent, major complications in 2.2 per cent, and late complications in 5.5 per cent of patients. There were no perforations or early hernia recurrence. The 30-day reoperation rate was 1.1 per cent. For patients with available 1-year follow-up, the overall recurrence rate was 18.5 per cent with a mean follow-up of 30 months (range, 12 to 51 months). LHR repair with mesh is associated with low perioperative morbidity and no mortality. The use of bioabsorbable mesh appears to be safe with no early hiatal hernia recurrence or late mesh erosion. Longer follow-up is needed to determine the long-term rate of hernia recurrence associated with LHR with mesh.

  18. Optimization-based mesh correction with volume and convexity constraints

    Science.gov (United States)

    D'Elia, Marta; Ridzal, Denis; Peterson, Kara J.; Bochev, Pavel; Shashkov, Mikhail

    2016-05-01

    We consider the problem of finding a mesh such that 1) it is the closest, with respect to a suitable metric, to a given source mesh having the same connectivity, and 2) the volumes of its cells match a set of prescribed positive values that are not necessarily equal to the cell volumes in the source mesh. This volume correction problem arises in important simulation contexts, such as satisfying a discrete geometric conservation law and solving transport equations by incremental remapping or similar semi-Lagrangian transport schemes. In this paper we formulate volume correction as a constrained optimization problem in which the distance to the source mesh defines an optimization objective, while the prescribed cell volumes, mesh validity and/or cell convexity specify the constraints. We solve this problem numerically using a sequential quadratic programming (SQP) method whose performance scales with the mesh size. To achieve scalable performance we develop a specialized multigrid-based preconditioner for optimality systems that arise in the application of the SQP method to the volume correction problem. Numerical examples illustrate the importance of volume correction, and showcase the accuracy, robustness and scalability of our approach.

  19. Palatomaxillary reconstruction with titanium mesh and radial forearm flap.

    Science.gov (United States)

    Sun, Guowen; Yang, Xudong; Tang, Enyi; Wen, Jianmin; Lu, Mingxing; Hu, Qingang

    2009-10-01

    The purpose of this study was to assess the treatment and prognosis of the palatomaxillary reconstruction with titanium mesh and the free radial forearm flap. This is a retrospective study of 19 patients with palatomaxillary defects who underwent immediate reconstruction using titanium mesh and a radial forearm flap during the 4-year period from 2004 to 2008. Intraoperatively, the titanium mesh was fixed to the residual bones for the reconstruction of hard-tissue defect after the tumor resection; then the free radial forearm flap was harvested to repair the soft-tissue defect, serving as the intraoral lining and titanium mesh covering. Postoperative esthetic appearance and function were followed-up. All of the patients achieved a satisfactory facial appearance. The speech assessment was good, and the oronasal reflux did not occur in all patients. Only 3 patients had titanium mesh exposure during the follow-up period. The free radial forearm flap with folded titanium mesh is a reliable option for reconstruction of palatomaxillary defects. It is highly effective for swallowing and speech rehabilitation as well as esthetic reconstruction.

  20. 3D Mesh Compression and Transmission for Mobile Robotic Applications

    Directory of Open Access Journals (Sweden)

    Bailin Yang

    2016-01-01

    Full Text Available Mobile robots are useful for environment exploration and rescue operations. In such applications, it is crucial to accurately analyse and represent an environment, providing appropriate inputs for motion planning in order to support robot navigation and operations. 2D mapping methods are simple but cannot handle multilevel or multistory environments. To address this problem, 3D mapping methods generate structural 3D representations of the robot operating environment and its objects by 3D mesh reconstruction. However, they face the challenge of efficiently transmitting those 3D representations to system modules for 3D mapping, motion planning, and robot operation visualization. This paper proposes a quality-driven mesh compression and transmission method to address this. Our method is efficient, as it compresses a mesh by quantizing its transformed vertices without the need to spend time constructing an a-priori structure over the mesh. A visual distortion function is developed to govern the level of quantization, allowing mesh transmission to be controlled under different network conditions or time constraints. Our experiments demonstrate how the visual quality of a mesh can be manipulated by the visual distortion function.