Highly Symmetric and Congruently Tiled Meshes for Shells and Domes

Science.gov (United States)

Rasheed, Muhibur; Bajaj, Chandrajit

2016-01-01

We describe the generation of all possible shell and dome shapes that can be uniquely meshed (tiled) using a single type of mesh face (tile), and following a single meshing (tiling) rule that governs the mesh (tile) arrangement with maximal vertex, edge and face symmetries. Such tiling arrangements or congruently tiled meshed shapes, are frequently found in chemical forms (fullerenes or Bucky balls, crystals, quasi-crystals, virus nano shells or capsids), and synthetic shapes (cages, sports domes, modern architectural facades). Congruently tiled meshes are both aesthetic and complete, as they support maximal mesh symmetries with minimal complexity and possess simple generation rules. Here, we generate congruent tilings and meshed shape layouts that satisfy these optimality conditions. Further, the congruent meshes are uniquely mappable to an almost regular 3D polyhedron (or its dual polyhedron) and which exhibits face-transitive (and edge-transitive) congruency with at most two types of vertices (each type transitive to the other). The family of all such congruently meshed polyhedra create a new class of meshed shapes, beyond the well-studied regular, semi-regular and quasi-regular classes, and their duals (platonic, Catalan and Johnson). While our new mesh class is infinite, we prove that there exists a unique mesh parametrization, where each member of the class can be represented by two integer lattice variables, and moreover efficiently constructable. PMID:27563368

A simplified treatment of the boundary conditions of the k- ε model in coarse-mesh CFD-type codes

International Nuclear Information System (INIS)

Analytis, G.Th.; Andreani, M.

1999-01-01

In coarse-mesh, CFD-type codes such as the containment analysis code GOTHIC, one of the options that can be used for modelling of turbulence is the k - ε model. However, in contrast to most other CFD codes which are designed to perform detailed CFD calculations with a large number of spatial meshes, codes such as GOTHIC are primarily aimed at simplified calculation of transients in large spaces (e.g., reactor containments), and generally use coarse meshes. The solution of the two parabolic equations for the k - ε model requires the definition of boundary conditions at physical boundaries and this, in turn, requires very small spatial meshes near these boundaries. Hence, while in codes like CFX this is done in a rigorous and consistent manner, codes like GOTHIC adopt an indirect and heuristic approach, due to the fact that the spatial meshes are usually large. This can have adverse consequences during the calculation of a transient and in this work, we shall give some examples of this and outline a method by which this problem can be avoided. (author)

Optimization of the spatial mesh for numerical solution of the neutron transport equation in a cluster-type lattice cell

International Nuclear Information System (INIS)

Davis, R.S.

2012-01-01

For programs that solve the neutron transport equation with an approximation that the neutron flux is constant in each space in a user-defined mesh, optimization of that mesh yields benefits in computing time and attainable precision. The previous best practice does not optimize the mesh thoroughly, because a large number of test runs of the solving software would be necessary. The method presented here optimizes the mesh for a flux that is based on conventional approximations but is more informative, so that a minimal number of parameters, one per type of material, must be adjusted by test runs to achieve thorough optimization. For a 37 element, natural-uranium, CANDU lattice cell, the present optimization yields 7 to 12 times (depending on the criterion) better precision than the previous best practice in 37% less computing time. (author)

RGG: Reactor geometry (and mesh) generator

International Nuclear Information System (INIS)

Jain, R.; Tautges, T.

2012-01-01

The reactor geometry (and mesh) generator RGG takes advantage of information about repeated structures in both assembly and core lattices to simplify the creation of geometry and mesh. It is released as open source software as a part of the MeshKit mesh generation library. The methodology operates in three stages. First, assembly geometry models of various types are generated by a tool called AssyGen. Next, the assembly model or models are meshed by using MeshKit tools or the CUBIT mesh generation tool-kit, optionally based on a journal file output by AssyGen. After one or more assembly model meshes have been constructed, a tool called CoreGen uses a copy/move/merge process to arrange the model meshes into a core model. In this paper, we present the current state of tools and new features in RGG. We also discuss the parallel-enabled CoreGen, which in several cases achieves super-linear speedups since the problems fit in available RAM at higher processor counts. Several RGG applications - 1/6 VHTR model, 1/4 PWR reactor core, and a full-core model for Monju - are reported. (authors)

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 m...... mesh (medit format). img2off Convert isosurface in image to surface mesh (off format). off2mesh Convert surface mesh (off format) to volumetric mesh (medit format). reduce Crop and resize 3D and stacks of images. data Example data to test the library on...

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.

Toward An Unstructured Mesh Database

Science.gov (United States)

Rezaei Mahdiraji, Alireza; Baumann, Peter Peter

2014-05-01

-incidence relationships. We instrument ImG model with sets of optional and application-specific constraints which can be used to check validity of meshes for a specific class of object such as manifold, pseudo-manifold, and simplicial manifold. We conducted experiments to measure the performance of the graph database solution in processing mesh queries and compare it with GrAL mesh library and PostgreSQL database on synthetic and real mesh datasets. The experiments show that each system perform well on specific types of mesh queries, e.g., graph databases perform well on global path-intensive queries. In the future, we investigate database operations for the ImG model and design a mesh query language.

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.

Connectivity editing for quadrilateral meshes

KAUST Repository

Peng, Chihan; Zhang, Eugene; Kobayashi, Yoshihiro; Wonka, Peter

2011-01-01

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 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.

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.

Adaptive hybrid mesh refinement for multiphysics applications

International Nuclear Information System (INIS)

Khamayseh, Ahmed; Almeida, Valmor de

2007-01-01

The accuracy and convergence of computational solutions of mesh-based methods is strongly dependent on the quality of the mesh used. We have developed methods for optimizing meshes that are comprised of elements of arbitrary polygonal and polyhedral type. We present in this research the development of r-h hybrid adaptive meshing technology tailored to application areas relevant to multi-physics modeling and simulation. Solution-based adaptation methods are used to reposition mesh nodes (r-adaptation) or to refine the mesh cells (h-adaptation) to minimize solution error. The numerical methods perform either the r-adaptive mesh optimization or the h-adaptive mesh refinement method on the initial isotropic or anisotropic meshes to equidistribute weighted geometric and/or solution error function. We have successfully introduced r-h adaptivity to a least-squares method with spherical harmonics basis functions for the solution of the spherical shallow atmosphere model used in climate modeling. In addition, application of this technology also covers a wide range of disciplines in computational sciences, most notably, time-dependent multi-physics, multi-scale modeling and simulation

Mesh Excision: Is Total Mesh Excision Necessary?

Science.gov (United States)

Wolff, Gillian F; Winters, J Christian; Krlin, Ryan M

2016-04-01

Nearly 29% of women will undergo a secondary, repeat operation for pelvic organ prolapse (POP) symptom recurrence following a primary repair, as reported by Abbott et al. (Am J Obstet Gynecol 210:163.e1-163.e1, 2014). In efforts to decrease the rates of failure, graft materials have been utilized to augment transvaginal repairs. Following the success of using polypropylene mesh (PPM) for stress urinary incontinence (SUI), the use of PPM in the transvaginal repair of POP increased. However, in recent years, significant concerns have been raised about the safety of PPM mesh. Complications, some specific to mesh, such as exposures, erosion, dyspareunia, and pelvic pain, have been reported with increased frequency. In the current literature, there is not substantive evidence to suggest that PPM has intrinsic properties that warrant total mesh removal in the absence of complications. There are a number of complications that can occur after transvaginal mesh placement that do warrant surgical intervention after failure of conservative therapy. In aggregate, there are no high-quality controlled studies that clearly demonstrate that total mesh removal is consistently more likely to achieve pain reduction. In the cases of obstruction and erosion, it seems clear that definitive removal of the offending mesh is associated with resolution of symptoms in the majority of cases and reasonable practice. There are a number of complications that can occur with removal of mesh, and patients should be informed of this as they formulate a choice of treatment. We will review these considerations as we examine the clinical question of whether total versus partial removal of mesh is necessary for the resolution of complications following transvaginal mesh placement.

Converting skeletal structures to quad dominant meshes

DEFF Research Database (Denmark)

Bærentzen, Jakob Andreas; Misztal, Marek Krzysztof; Welnicka, Katarzyna

2012-01-01

We propose the Skeleton to Quad-dominant polygonal Mesh algorithm (SQM), which converts skeletal structures to meshes composed entirely of polar and annular regions. Both types of regions have a regular structure where all faces are quads except for a single ring of triangles at the center of each...

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

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

Science.gov (United States)

Shah, Hemendra N.; Badlani, Gopal H.

2012-01-01

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, its magnitude

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

Fog water collection effectiveness: Mesh intercomparisons

Science.gov (United States)

Fernandez, Daniel; Torregrosa, Alicia; Weiss-Penzias, Peter; Zhang, Bong June; Sorensen, Deckard; Cohen, Robert; McKinley, Gareth; Kleingartner, Justin; Oliphant, Andrew; Bowman, Matthew

2018-01-01

To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014–2016) at four California sites. SFCs were deployed with: standard 1.00 m2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s–1 and 45% less for wind speeds greater than 5 m s–1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of steel mesh collected 3% more and at wind speeds of 4–5 m s–1, it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Notes on the Mesh Handler and Mesh Data Conversion

International Nuclear Information System (INIS)

Lee, Sang Yong; Park, Chan Eok

2009-01-01

At the outset of the development of the thermal-hydraulic code (THC), efforts have been made to utilize the recent technology of the computational fluid dynamics. Among many of them, the unstructured mesh approach was adopted to alleviate the restriction of the grid handling system. As a natural consequence, a mesh handler (MH) has been developed to manipulate the complex mesh data from the mesh generator. The mesh generator, Gambit, was chosen at the beginning of the development of the code. But a new mesh generator, Pointwise, was introduced to get more flexible mesh generation capability. An open source code, Paraview, was chosen as a post processor, which can handle unstructured as well as structured mesh data. Overall data processing system for THC is shown in Figure-1. There are various file formats to save the mesh data in the permanent storage media. A couple of dozen of file formats are found even in the above mentioned programs. A competent mesh handler should have the capability to import or export mesh data as many as possible formats. But, in reality, there are two aspects that make it difficult to achieve the competence. The first aspect to consider is the time and efforts to program the interface code. And the second aspect, which is even more difficult one, is the fact that many mesh data file formats are proprietary information. In this paper, some experience of the development of the format conversion programs will be presented. File formats involved are Gambit neutral format, Ansys-CFX grid file format, VTK legacy file format, Nastran format and CGNS

In vitro extracellular matrix model to evaluate stroma cell response to transvaginal mesh.

Science.gov (United States)

Wu, Ming-Ping; Huang, Kuan-Hui; Long, Cheng-Yu; Yang, Chau-Chen; Tong, Yat-Ching

2014-04-01

The use of surgical mesh for female pelvic floor reconstruction has increased in recent years. However, there is paucity of information about the biological responses of host stroma cells to different meshes. This study was aimed to establish an in vitro experimental model to study the micro-environment of extracellular matrix (ECM) with embedded mesh and the stroma cell behaviors to different synthetic meshes. Matrigel multi-cellular co-culture system with embedded mesh was used to evaluate the interaction of stroma cells and synthetic mesh in a simulated ECM environment. Human umbilical vein endothelial cells (HUVEC) and NIH3T3 fibroblasts were inoculated in the system. The established multi-cellular Matrigel co-culture system was used to detect stroma cell recruitment and tube formation ability for different synthetic meshes. HUVEC and NIH3T3 cells were recruited into the mesh interstices and organized into tube-like structures in type I mesh material from Perigee, Marlex and Prolift 24 hr after cell inoculation. On the contrary, there was little recruitment of HUVEC and NIH3T3 cells into the type III mesh of intra-vaginal sling (IVS). The Matrigel multi-cellular co-culture system with embedded mesh offers a useful in vitro model to study the biological behaviors of stroma cells in response to different types of synthetic meshes. The system can help to select ideal mesh candidates before actual implantation into the human body. © 2013 Wiley Periodicals, Inc.

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.

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

International Nuclear Information System (INIS)

Joo, H.; Nichols, W.R.

1994-01-01

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

Fog water collection effectiveness: Mesh intercomparisons

Science.gov (United States)

Fernandez, Daniel; Torregrosa, Alicia; Weiss-Penzias, Peter; Zhang, Bong June; Sorensen, Deckard; Cohen, Robert; McKinley, Gareth; Kleingartner, Justin; Oliphant, Andrew; Bowman, Matthew

2018-01-01

To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014–2016) at four California sites. SFCs were deployed with: standard 1.00 m2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s–1 and 45% less for wind speeds greater than 5 m s–1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of wind speeds of 4–5 m s–1, it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Transvaginal mesh in the media following the 2011 US food and drug administration public health notification update.

Science.gov (United States)

Koo, Kevin; Gormley, E Ann

2017-02-01

Prompted by patients' changing perceptions of transvaginal mesh, this study examines how mesh has been reported in the news following the 2011 US Food and Drug Administration (FDA) updated notification about the use of mesh in the treatment of pelvic organ prolapse. Two national newspaper databases were queried for articles discussing transvaginal mesh published within 3 years of the FDA announcement. Content analysis included headline subjects, mesh-related complications, quoted sources, and the FDA recommendations. To determine whether more widely read sources publish higher quality reporting, a subgroup analysis was conducted based on newspaper circulation. Ninety-five articles met inclusion criteria. Mesh-related litigation was the most common headline subject (36 articles, 38%), and 54% of all articles referenced legal action. Fifty-seven articles (60%) cited at least one mesh-related complication. Only 18 articles (19%) quoted surgeons who use transvaginal mesh. For the FDA update, 40% of articles that first reported the announcement accurately specified that it applies to mesh for prolapse, not incontinence. This ambiguity persisted: half of all articles cited the warning, but only 23% distinguished between prolapse and incontinence. Higher newspaper circulation did not significantly improve the quality of reporting about the content or context of the FDA's recommendations. Despite frequent media coverage of transvaginal mesh and its complications since 2011, very few news sources that cited the FDA warning distinguished between prolapse and incontinence. Given prevalent reporting of mesh-related litigation, the findings raise concern about how patients perceive the safety and efficacy of transvaginal mesh, regardless of indication. Neurourol. Urodynam. 36:329-332, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Mesh networks: an optimum solution for AMR

Energy Technology Data Exchange (ETDEWEB)

Mimno, G.

2003-12-01

Characteristics of mesh networks and the advantage of using them in automatic meter reading equipment (AMR) are discussed. Mesh networks are defined as being similar to a fishing net made of knots and links. In mesh networks the knots represent meter sites and the links are the radio paths between the meter sites and the neighbourhood concentrator. In mesh networks any knot in the communications chain can link to any other and the optimum path is calculated by the network by hopping from meter to meter until the radio message reaches a concentrator. This mesh communications architecture is said to be vastly superior to many older types of radio-based meter reading technologies; its main advantage is that it not only significantly improves the economics of fixed network deployment, but also supports time-of-use metering, remote disconnect services and advanced features, such as real-time pricing, demand response, and other efficiency measures, providing a better return on investment and reliability.

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.

Transrectal Mesh Erosion Requiring Bowel Resection.

Science.gov (United States)

Kemp, Marta Maria; Slim, Karem; Rabischong, Benoît; Bourdel, Nicolas; Canis, Michel; Botchorishvili, Revaz

To report a case of a transrectal mesh erosion as complication of laparoscopic promontofixation with mesh repair, necessitating bowel resection and subsequent surgical interventions. Sacrocolpopexy has become a standard procedure for vaginal vault prolapse [1], and the laparoscopic approach has gained popularity owing to more rapid recovery and less morbidity [2,3]. Mesh erosion is a well-known complication of surgical treatment for prolapse as reported in several negative evaluations, including a report from the US Food and Drug Administration in 2011 [4]. Mesh complications are more common after surgeries via the vaginal approach [5]; nonetheless, the incidence of vaginal mesh erosion after laparoscopic procedures is as high as 9% [6]. The incidence of transrectal mesh exposure after laparoscopic ventral rectopexy is roughly 1% [7]. The diagnosis may be delayed because of its rarity and variable presentation. In addition, polyester meshes, such as the mesh used in this case, carry a higher risk of exposure [8]. A 57-year-old woman experiencing genital prolapse, with the cervix classified as +3 according to the Pelvic Organ Prolapse Quantification system, underwent laparoscopic standard sacrocolpopexy using polyester mesh. Subtotal hysterectomy and bilateral adnexectomy were performed concomitantly. A 3-year follow-up consultation demonstrated no signs or symptoms of erosion of any type. At 7 years after the surgery, however, the patient presented with rectal discharge, diagnosed as infectious rectocolitis with the isolation of Clostridium difficile. She underwent a total of 5 repair surgeries in a period of 4 months, including transrectal resection of exposed mesh, laparoscopic ablation of mesh with digestive resection, exploratory laparoscopy with abscess drainage, and exploratory laparoscopy with ablation of residual mesh and transverse colostomy. She recovered well after the last intervention, exhibiting no signs of vaginal or rectal fistula and no recurrence

Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair.

Science.gov (United States)

Melman, L; Jenkins, E D; Hamilton, N A; Bender, L C; Brodt, M D; Deeken, C R; Greco, S C; Frisella, M M; Matthews, B D

2011-08-01

To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard(®)Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO(®) (LWPP, Ethicon, http://www.ethicon.com), and GORE(®)INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However, over time, inflammation decreased significantly for all mesh types (P 0.09). The maximum tensile strength of mesh in the abdominal wall decreased over time for HWPP, LWPP, and mkPTFE mesh materials alike. This trend may actually reflect inability to adequately grip specimens at later time points

Development of a mesh-type computer tomography for the two-phase flow

International Nuclear Information System (INIS)

Lee, Jae Young; Lee, In Wook

1998-01-01

This paper is to describe the development of a mesh-type computer tomography for the two-phase flow. The sensor is made of many parallel wires in the orthogonal orientation. A demultiplexer circuits is developed for electrodes to supply driving voltage and for data acquisition system to get the output voltage form the electrode unit. For the reconstruction of image a direct inversion algorithm is adopted. Full automation is provided from the data sensing to the image construction. Through the careful calibariation and field tests in the horizontal and vertical two-phase loop, the present sensor detect images for the solitary wave and the slug realistically. This sensor could be a useful tool in the laboratory experiments

The mesh controversy [version 1; referees: 2 approved

OpenAIRE

Joshua A. Cohn; Elizabeth Timbrook Brown; Casey G. Kowalik; Melissa R. Kaufmann; Roger R. Dmochowski; W. Stuart Reynolds

2016-01-01

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 recla...

The Analysis of the Usefulness of Welded Meshes to Embankment Reinforcement

Directory of Open Access Journals (Sweden)

Ćwirko Marcin

2017-09-01

Full Text Available The aim of this paper was to find an answer to the question about the possibility of using steel welded mesh in building the retaining walls of gabion baskets. In light of the currently used gabion structure solutions, among which double-woven mesh is much more popular, the focus was put on the possibility of using welded mesh. A numerical analysis was conducted to examine the behavior of welded and woven mesh subjected to various loads and the results obtained for both types of mesh were directly compared. The maximal displacement in mesh nodes was admitted as the measurement of the system behavior (in the case of both undamaged and damaged mesh.

Different types of mesh fixation for laparoscopic repair of inguinal hernia: A protocol for systematic review and network meta-analysis with randomized controlled trials.

Science.gov (United States)

Wei, Kongyuan; Lu, Cuncun; Ge, Long; Pan, Bei; Yang, Huan; Tian, Jinhui; Cao, Nong

2018-04-01

Laparoscopic inguinal hernia repair has become a valid option for repair of an inguinal hernia. Due to there are several types of mesh fixation for laparoscopic repair of inguinal hernia. The study aims to assess and compare the efficacy of different types of mesh fixation for laparoscopic repair of inguinal hernia using network meta-analysis. We will systematically search PubMed, EMBASE the Cochrane library, and Chinese Biomedical Literature Database from their inception to March 2018. Randomized controlled trials (RCTs) that compared the effect of different types of mesh fixation for laparoscopic inguinal hernia repair will be included. The primary outcomes are chronic groin pain, incidence risk of hernia recurrence, and complications. Risk of bias assessment of the included RCTs will be conducted using to Cochrane risk of bias tool. A network meta-analysis will be performed using WinBUGS 1.4.3 software and the result figures will be generated using R x64 3.1.2 software and STATA V.12.0 software. Grading of Recommendations Assessment, Development and Evaluation (GRADE) will be used to assess the quality of evidence. The results of this study will be published in a peer-reviewed journal. Our study will generate evidence of laparoscopic repair of mesh fixation for adult patients with inguinal hernia and provide suggestions for clinical practice or guideline.

Suture-free and mesh reinforced small intestinal anstomoses: a feasibility study in rabbits.

Science.gov (United States)

Ulmer, T F; Stumpf, M; Rosch, R; Junge, K; Binnebösel, M; von Trotha, K T; Oettinger, A P; Neumann, U

2013-08-01

Anastomotic leakage still remains a major complication in general surgery. Beside general risk factors, the ideal method of anastomotic technique has not been found until now. The aim of the present study was to analyze wound healing in suture-free small intestine anastomoses using fibrin glue with and without mesh-reinforcement. Laparotomy and four different types of small bowel anastomoses were performed in 32 chinchilla rabbits. Standard hand-sewn anastomoses (CG), suture-free glued anastomoses (FG) with and without mesh reinforcement using two different types of meshes [Vicryl-mesh (VM) and Surgisis (SM)]. Animals were sacrificed after 5 and 21 days. Bursting pressure, collagen type I/III ratio, and matrix-metalloproteinase 2, 9, and 13 were analyzed. None of the animals died due to an anastomotic leakage. All animals in the long term group with Surgisis mesh died due to a mechanical bowel obstruction based on a distinctive stenosis of the anastomosis. The bursting pressures did significantly differed in animals with fibrin glue alone compared to animals with Vicryl-mesh reinforcement (p < 0.05). Histological examination revealed statistically significant differences (p < 0.05) in the values for MMP-2 (VM < SM), MMP-9 (VM < CG), and MMP-13 (CG < SM, VM < FG, and VM < SM). However, collagen type I/III ratios were not significantly different between groups. Our results suggest that a mesh reinforced glued anastomosis is technically feasible. Furthermore, mesh-reinforcement using VM increased the integrity and simplified the technique of suture-free anastomoses.

Modelling axisymmetric cod-ends made of different mesh types

DEFF Research Database (Denmark)

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

2009-01-01

the selectivity process has become more important. This paper presents a model of the deformation of an axisymmetric cod-end. The twine tension and the catch pressure acting on the knots of each mesh along the cod-end profile are calculated, and a Newton-Raphson scheme is used to estimate the equilibrium position...

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.

The Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMACIONIZE

Science.gov (United States)

Vandenbroucke, B.; Wood, K.

2018-04-01

We present the public Monte Carlo photoionization and moving-mesh radiation hydrodynamics code CMACIONIZE, which can be used to simulate the self-consistent evolution of HII regions surrounding young O and B stars, or other sources of ionizing radiation. The code combines a Monte Carlo photoionization algorithm that uses a complex mix of hydrogen, helium and several coolants in order to self-consistently solve for the ionization and temperature balance at any given type, with a standard first order hydrodynamics scheme. The code can be run as a post-processing tool to get the line emission from an existing simulation snapshot, but can also be used to run full radiation hydrodynamical simulations. Both the radiation transfer and the hydrodynamics are implemented in a general way that is independent of the grid structure that is used to discretize the system, allowing it to be run both as a standard fixed grid code, but also as a moving-mesh code.

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.

Finite element simulation of impact response of wire mesh screens

Directory of Open Access Journals (Sweden)

Wang Caizheng

2015-01-01

Full Text Available In this paper, the response of wire mesh screens to low velocity impact with blunt objects is investigated using finite element (FE simulation. The woven wire mesh is modelled with homogeneous shell elements with equivalent smeared mechanical properties. The mechanical behaviour of the woven wire mesh was determined experimentally with tensile tests on steel wire mesh coupons to generate the data for the smeared shell material used in the FE. The effects of impacts with a low mass (4 kg and a large mass (40 kg providing the same impact energy are studied. The joint between the wire mesh screen and the aluminium frame surrounding it is modelled using contact elements with friction between the corresponding elements. Damage to the screen of different types compromising its structural integrity, such as mesh separation and pulling out from the surrounding frame is modelled. The FE simulation is validated with results of impact tests conducted on woven steel wire screen meshes.

The Role of Chronic Mesh Infection in Delayed-Onset Vaginal Mesh Complications or Recurrent Urinary Tract Infections: Results From Explanted Mesh Cultures.

Science.gov (United States)

Mellano, Erin M; Nakamura, Leah Y; Choi, Judy M; Kang, Diana C; Grisales, Tamara; Raz, Shlomo; Rodriguez, Larissa V

2016-01-01

Vaginal mesh complications necessitating excision are increasingly prevalent. We aim to study whether subclinical chronically infected mesh contributes to the development of delayed-onset mesh complications or recurrent urinary tract infections (UTIs). Women undergoing mesh removal from August 2013 through May 2014 were identified by surgical code for vaginal mesh removal. Only women undergoing removal of anti-incontinence mesh were included. Exclusion criteria included any women undergoing simultaneous prolapse mesh removal. We abstracted preoperative and postoperative information from the medical record and compared mesh culture results from patients with and without mesh extrusion, de novo recurrent UTIs, and delayed-onset pain. One hundred seven women with only anti-incontinence mesh removed were included in the analysis. Onset of complications after mesh placement was within the first 6 months in 70 (65%) of 107 and delayed (≥6 months) in 37 (35%) of 107. A positive culture from the explanted mesh was obtained from 82 (77%) of 107 patients, and 40 (37%) of 107 were positive with potential pathogens. There were no significant differences in culture results when comparing patients with delayed-onset versus immediate pain, extrusion with no extrusion, and de novo recurrent UTIs with no infections. In this large cohort of patients with mesh removed for a diverse array of complications, cultures of the explanted vaginal mesh demonstrate frequent low-density bacterial colonization. We found no differences in culture results from women with delayed-onset pain versus acute pain, vaginal mesh extrusions versus no extrusions, or recurrent UTIs using standard culture methods. Chronic prosthetic infections in other areas of medicine are associated with bacterial biofilms, which are resistant to typical culture techniques. Further studies using culture-independent methods are needed to investigate the potential role of chronic bacterial infections in delayed vaginal mesh

In-vitro examination of the biocompatibility of fibroblast cell lines on alloplastic meshes and sterilized polyester mosquito mesh.

Science.gov (United States)

Wiessner, R; Kleber, T; Ekwelle, N; Ludwig, K; Richter, D-U

2017-06-01

The use of alloplastic implants for tissue strengthening when treating hernias is an established therapy worldwide. Despite the high incidence of hernias in Africa and Asia, the implantation of costly mesh netting is not financially feasible. Because of that various investigative groups have examined the use of sterilized mosquito netting. The animal experiments as well as the clinical trials have both shown equivalent short- and long-term results. The goal of this paper is the comparison of biocompatibility of human fibroblasts on the established commercially available nets and on sterilized polyester mosquito mesh over a period of 12 weeks. Three commercially available plastic mesh types and a gas-sterilized mosquito polyethylenterephtalate (polyester) mesh were examined. Human fibroblasts from subcutaneous healthy tissue were used. Various tests for evaluating the growth behavior and the cell morphology of human fibroblasts were conducted. The semi-quantitative (light microscopy) and qualitative (scanning electron microscopy) analyses were performed after 1 week and then again after 12 weeks. The cell proliferation and cytotoxicity of the implants were investigated with the help of the 5'-bromo-2'-deoxyuridine (BrdU)-cell proliferation test and the LDH-cytotoxicity test. The number of live cells per ml was determined with the Bürker counting chamber. In addition, analyses were made of the cell metabolism (oxidative stress) by measuring the pH value, hydrogen peroxide, and glycolysis. After 12 weeks, a proliferation of fibroblasts on all mesh is documented. No mesh showed a complete apoptosis of the cells. This qualitative observation could be confirmed quantitatively in a biochemical assay by marking the proliferating cells with BrdU. The biochemical analysis brought the proof that the materials used, including the polyester of the mosquito mesh, are not cytotoxic for the fibroblasts. The vitality of the cells was between 94 and 98%. The glucose metabolism

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.

Urogynecologic Surgical Mesh Implants

Science.gov (United States)

... procedures performed to treat pelvic floor disorders with surgical mesh: Transvaginal mesh to treat POP Transabdominal mesh to treat ... address safety risks Final Order for Reclassification of Surgical Mesh for Transvaginal Pelvic Organ Prolapse Repair Final Order for Effective ...

Intravesical midurethral sling mesh erosion secondary to transvaginal mesh reconstructive surgery

Directory of Open Access Journals (Sweden)

Sukanda Bin Jaili

2015-05-01

Conclusion: Repeated vaginal reconstructive surgery may jeopardize a primary mesh or sling, and pose a high risk of mesh erosion, which may be delayed for several years. Removal of the mesh erosion and bladder repair are feasible pervaginally with good outcome.

Mesh versus non-mesh repair of ventral abdominal hernias

International Nuclear Information System (INIS)

Jawaid, M.A.; Talpur, A.H.

2008-01-01

To investigate the relative effectiveness of mesh and suture repair of ventral abdominal hernias in terms of clinical outcome, quality of life and rate of recurrence in both the techniques. This is a retrospective descriptive analysis of 236 patients with mesh and non-mesh repair of primary ventral hernias performed between January 2000 to December 2004 at Surgery Department, Liaquat University of Medical and Health Sciences, Jamshoro. The record sheets of the patients were analyzed and data retrieved to compare the results of both techniques for short-term and long-term results. The data retrieved is statistically analyzed on SPSS version 11. There were 43 (18.22%) males and 193 (81.77%) females with a mean age of 51.79 years and a range of 59 (81-22). Para-umbilical hernia was the commonest of ventral hernia and accounted for 49.8% (n=118) of the total study population followed by incisional hernia comprising 24% (n=57) of the total number. There was a significant difference in the recurrent rate at 3 years interval with 23/101 (22.77%) recurrences in suture-repaired subjects compared to 10/135 (7.40%) in mesh repair group. Chronic pain lasting up to 1-2 years was noted in 14 patients with suture repair. Wound infection is comparatively more common (8.14%) in mesh group. The other variables such as operative and postoperative complications, total hospital stay and quality of life is also discussed. Mesh repair of ventral hernia is much superior to non-mesh suture repair in terms of recurrence and overall outcome. (author)

Parallel adaptation of general three-dimensional hybrid meshes

International Nuclear Information System (INIS)

Kavouklis, Christos; Kallinderis, Yannis

2010-01-01

A new parallel dynamic mesh adaptation and load balancing algorithm for general hybrid grids has been developed. The meshes considered in this work are composed of four kinds of elements; tetrahedra, prisms, hexahedra and pyramids, which poses a challenge to parallel mesh adaptation. Additional complexity imposed by the presence of multiple types of elements affects especially data migration, updates of local data structures and interpartition data structures. Efficient partition of hybrid meshes has been accomplished by transforming them to suitable graphs and using serial graph partitioning algorithms. Communication among processors is based on the faces of the interpartition boundary and the termination detection algorithm of Dijkstra is employed to ensure proper flagging of edges for refinement. An inexpensive dynamic load balancing strategy is introduced to redistribute work load among processors after adaptation. In particular, only the initial coarse mesh, with proper weighting, is balanced which yields savings in computation time and relatively simple implementation of mesh quality preservation rules, while facilitating coarsening of refined elements. Special algorithms are employed for (i) data migration and dynamic updates of the local data structures, (ii) determination of the resulting interpartition boundary and (iii) identification of the communication pattern of processors. Several representative applications are included to evaluate the method.

Mesh removal following transvaginal mesh placement: a case series of 104 operations.

Science.gov (United States)

Marcus-Braun, Naama; von Theobald, Peter

2010-04-01

The objective of the study was to reveal the way we treat vaginal mesh complications in a trained referral center. This is a retrospective review of all patients who underwent surgical removal of transvaginal mesh for mesh-related complications during a 5-year period. Eighty-three patients underwent 104 operations including 61 complete mesh removal, 14 partial excision, 15 section of sub-urethral sling, and five laparoscopies. Main indications were erosion, infection, granuloma, incomplete voiding, and pain. Fifty-eight removals occurred more than 2 years after the primary mesh placement. Mean operation time was 21 min, and there were two intraoperative and ten minor postoperative complications. Stress urinary incontinence (SUI) recurred in 38% and cystocele in 19% of patients. In a trained center, mesh removal was found to be a quick and safe procedure. Mesh-related complications may frequently occur more than 2 years after the primary operation. Recurrence was mostly associated with SUI and less with genital prolapse.

LOOM-P: a finite element mesh generation program with on-line graphic display

International Nuclear Information System (INIS)

Ise, Takeharu; Yamazaki, Toshio.

1977-06-01

A description of the two-dimensional mesh generation program, LOOM-P, is given in detail. The program is developed newly to produce a mesh network for a reactor core geometry with the help of an automatic mesh generation routine built in it, under the control of the refresh-type graphic display. It is therefore similar to the edit program of the self-organizing mesh generator, QMESH-RENUM. Additional techniques are incorporated to improve the pattern of mesh elements by means of on-line conversational mode. The obtained mesh network is edited out as input data to the three-dimensional neutron diffusion theory code, FEM-BABEL. (auth.)

No. 351-Transvaginal Mesh Procedures for Pelvic Organ Prolapse.

Science.gov (United States)

Larouche, Maryse; Geoffrion, Roxana; Walter, Jens-Erik

2017-11-01

publications with study groups larger than 20 individuals were selected because this criterion was used in the largest meta-analysis referenced in this guideline. A total of 1470 studies were obtained; after selecting only applicable studies and excluding duplicates, 68 manuscripts were reviewed and included. The content and recommendations were drafted and agreed upon by the principal authors and members of the Urogynaecology Committee. The Board of the Society of Obstetricians and Gynaecologists of Canada approved the final draft for publication. The quality of evidence was rated using the criteria described in the Grading of Recommendations Assessment, Development and Evaluation methodology framework. The Summary of Findings is available upon request. It is expected that this guideline will benefit women with pelvic organ prolapse by ensuring that health care providers are aware of outcomes related to transvaginal mesh procedures and steps in the management of related complications. This should guide patient-informed consent before such procedures are undertaken. The benefits clearly outweigh the potential harms or costs of implementation of this guideline, although no direct harms or costs are identified. Evidence will be reviewed 5 years after publication to decide whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations. RECOMMENDATIONS. Copyright © 2017 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. Published by Elsevier Inc. All rights reserved.

Polygonal Prism Mesh in the Viscous Layers for the Polyhedral Mesh Generator, PolyGen

International Nuclear Information System (INIS)

Lee, Sang Yong; Park, Chan Eok; Kim, Shin Whan

2015-01-01

Polyhedral mesh has been known to have some benefits over the tetrahedral mesh. Efforts have been made to set up a polyhedral mesh generation system with open source programs SALOME and TetGen. The evaluation has shown that the polyhedral mesh generation system is promising. But it is necessary to extend the capability of the system to handle the viscous layers to be a generalized mesh generator. A brief review to the previous works on the mesh generation for the viscous layers will be made in section 2. Several challenging issues for the polygonal prism mesh generation will be discussed as well. The procedure to generate a polygonal prism mesh will be discussed in detail in section 3. Conclusion will be followed in section 4. A procedure to generate meshes in the viscous layers with PolyGen has been successfully designed. But more efforts have to be exercised to find the best way for the generating meshes for viscous layers. Using the extrusion direction of the STL data will the first of the trials in the near future

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.

MESH2D Grid generator design and use

Energy Technology Data Exchange (ETDEWEB)

Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-31

Mesh2d is a Fortran90 program originally 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). x-coordinates depending only on index i implies strictly vertical x-grid lines, whereas the y-grid lines can undulate. 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. Since the original development effort, Mesh2d has been extended to more general two-dimensional structured grids of the form [x(i,j),(i,j)].

Influence of mesh non-orthogonality on numerical simulation of buoyant jet flows

International Nuclear Information System (INIS)

Ishigaki, Masahiro; Abe, Satoshi; Sibamoto, Yasuteru; Yonomoto, Taisuke

2017-01-01

Highlights: • Influence of mesh non-orthogonality on numerical solution of buoyant jet flows. • Buoyant jet flows are simulated with hexahedral and prismatic meshes. • Jet instability with prismatic meshes may be overestimated compared to that with hexahedral meshes. • Modified solvers that can reduce the influence of mesh non-orthogonality and reduce computation time are proposed. - Abstract: In the present research, we discuss the influence of mesh non-orthogonality on numerical solution of a type of buoyant flow. Buoyant jet flows are simulated numerically with hexahedral and prismatic mesh elements in an open source Computational Fluid Dynamics (CFD) code called “OpenFOAM”. Buoyant jet instability obtained with the prismatic meshes may be overestimated compared to that obtained with the hexahedral meshes when non-orthogonal correction is not applied in the code. Although the non-orthogonal correction method can improve the instability generated by mesh non-orthogonality, it may increase computation time required to reach a convergent solution. Thus, we propose modified solvers that can reduce the influence of mesh non-orthogonality and reduce the computation time compared to the existing solvers in OpenFOAM. It is demonstrated that calculations for a buoyant jet with a large temperature difference are performed faster by the modified solver.

Influence of mesh non-orthogonality on numerical simulation of buoyant jet flows

Energy Technology Data Exchange (ETDEWEB)

Ishigaki, Masahiro, E-mail: ishigaki.masahiro@jaea.go.jp; Abe, Satoshi; Sibamoto, Yasuteru; Yonomoto, Taisuke

2017-04-01

Highlights: • Influence of mesh non-orthogonality on numerical solution of buoyant jet flows. • Buoyant jet flows are simulated with hexahedral and prismatic meshes. • Jet instability with prismatic meshes may be overestimated compared to that with hexahedral meshes. • Modified solvers that can reduce the influence of mesh non-orthogonality and reduce computation time are proposed. - Abstract: In the present research, we discuss the influence of mesh non-orthogonality on numerical solution of a type of buoyant flow. Buoyant jet flows are simulated numerically with hexahedral and prismatic mesh elements in an open source Computational Fluid Dynamics (CFD) code called “OpenFOAM”. Buoyant jet instability obtained with the prismatic meshes may be overestimated compared to that obtained with the hexahedral meshes when non-orthogonal correction is not applied in the code. Although the non-orthogonal correction method can improve the instability generated by mesh non-orthogonality, it may increase computation time required to reach a convergent solution. Thus, we propose modified solvers that can reduce the influence of mesh non-orthogonality and reduce the computation time compared to the existing solvers in OpenFOAM. It is demonstrated that calculations for a buoyant jet with a large temperature difference are performed faster by the modified solver.

Improving MeSH classification of biomedical articles using citation contexts.

Science.gov (United States)

Aljaber, Bader; Martinez, David; Stokes, Nicola; Bailey, James

2011-10-01

Medical Subject Headings (MeSH) are used to index the majority of databases generated by the National Library of Medicine. Essentially, MeSH terms are designed to make information, such as scientific articles, more retrievable and assessable to users of systems such as PubMed. This paper proposes a novel method for automating the assignment of biomedical publications with MeSH terms that takes advantage of citation references to these publications. Our findings show that analysing the citation references that point to a document can provide a useful source of terms that are not present in the document. The use of these citation contexts, as they are known, can thus help to provide a richer document feature representation, which in turn can help improve text mining and information retrieval applications, in our case MeSH term classification. In this paper, we also explore new methods of selecting and utilising citation contexts. In particular, we assess the effect of weighting the importance of citation terms (found in the citation contexts) according to two aspects: (i) the section of the paper they appear in and (ii) their distance to the citation marker. We conduct intrinsic and extrinsic evaluations of citation term quality. For the intrinsic evaluation, we rely on the UMLS Metathesaurus conceptual database to explore the semantic characteristics of the mined citation terms. We also analyse the "informativeness" of these terms using a class-entropy measure. For the extrinsic evaluation, we run a series of automatic document classification experiments over MeSH terms. Our experimental evaluation shows that citation contexts contain terms that are related to the original document, and that the integration of this knowledge results in better classification performance compared to two state-of-the-art MeSH classification systems: MeSHUP and MTI. Our experiments also demonstrate that the consideration of Section and Distance factors can lead to statistically

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.

Long-term follow-up of treatment for synthetic mesh complications.

Science.gov (United States)

Hansen, Brooke L; Dunn, Guinn Ellen; Norton, Peggy; Hsu, Yvonne; Nygaard, Ingrid

2014-01-01

The objectives of this study are (1) to describe the presenting symptoms, findings, and treatment and (2) to describe the self-reported improvement and function at least 6 months after presentation in women presenting to 1 urogynecology division for complications associated with synthetic vaginal mesh. Women evaluated between 2006 and 2011 were identified by diagnostic codes. We abstracted information from the medical record and attempted to contact all women to complete a follow-up telephone survey questionnaire consisting of several validated instruments. A total of 111 women were evaluated for complications associated with synthetic vaginal mesh. The mean interval from index surgery was 2.4 years. Of these, 84% were referred from outside hospitals. Index surgeries included vaginal mesh kits/vaginally placed mesh (47%), midurethral mesh slings (37%), abdominally placed vaginal mesh (11%), and vaginal mesh kit with concomitantly placed mesh sling (5%). The most common complications were extrusion (65%), contraction (17%), and chronic pelvic pain (16%). A total of 98 women underwent some type of treatment (85 surgical) by urogynecologists, pelvic pain specialists, or physical therapists. Eighty-four (76%) provided follow-up information at mean interval since presentation of 2.3 years. At follow-up, the mean (SD) Pelvic Floor Distress Inventory score was 98 (67), the mean (SD) EQ-5D index score was 0.69 (0.23), and 22% reported vaginal discharge, 15% vaginal bleeding or spotting, and 45% sexual abstinence due to problems related to mesh. A total of 71% reported being overall better, whereas 29% were the same or worse. Two years after tertiary care level multidisciplinary treatment of vaginal mesh complications, many women still report symptoms that negatively impact their quality of life.

Persistent pelvic pain following transvaginal mesh surgery: a cause for mesh removal.

Science.gov (United States)

Marcus-Braun, Naama; Bourret, Antoine; von Theobald, Peter

2012-06-01

Persistent pelvic pain after vaginal mesh surgery is an uncommon but serious complication that greatly affects women's quality of life. Our aim was to evaluate various procedures for mesh removal performed at a tertiary referral center in cases of persistent pelvic pain, and to evaluate the ensuing complications and outcomes. A retrospective study was conducted at the University Hospital of Caen, France, including all patients treated for removal or section of vaginal mesh due to pelvic pain as a primary cause, between January 2004 and September 2009. Ten patients met the inclusion criteria. Patients were diagnosed between 10 months and 3 years after their primary operation. Eight cases followed suburethral sling procedures and two followed mesh surgery for pelvic organ prolapse. Patients presented with obturator neuralgia (6), pudendal neuralgia (2), dyspareunia (1), and non-specific pain (1). The surgical treatment to release the mesh included: three cases of extra-peritoneal laparoscopy, four cases of complete vaginal mesh removal, one case of partial mesh removal and two cases of section of the suburethral sling. In all patients with obturator neuralgia, symptoms were resolved or improved, whereas in both cases of pudendal neuralgia the symptoms continued. There were no intra-operative complications. Post-operative Retzius hematoma was observed in one patient after laparoscopy. Mesh removal in a tertiary center is a safe procedure, necessary in some cases of persistent pelvic pain. Obturator neuralgia seems to be easier to treat than pudendal neuralgia. Early diagnosis is the key to success in prevention of chronic disease. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Thermal Analysis of Concrete Storage Cask with Bird Screen Meshes

Energy Technology Data Exchange (ETDEWEB)

Lee, Ju-Chan; Bang, K.S.; Yu, S.H.; Cho, S.S.; Choi, W.S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

In this study, a thermal analysis of the cask with bird screen meshes has been performed using a porous media model. The overpack consists of a structural material, a concrete shielding, and a ventilation system. Heat is removed from the cask to the environment by a passive means only. Air inlet and outlet ducts are installed at the bottom and top of the cask for a ventilation system. Bird screen meshes are installed at the air inlet and outlet ducts to inhibit intrusion of debris from the external environment. The presence of this screens introduce an additional resistance to air flow through the ducts. Five types of meshes for bird screen were considered in this study. The bird screen meshes at the inlet and outlet vents reduce the open area for flow by about 44 - 79 %. Flow resistance coefficients for porous media model were deduced from the fluid flow analysis of bird screen meshes. Thermal analyses for the concrete cask have been carried out using a porous media model. The analysis results agreed well with the test results. Therefore, it was shown that the porous media model for the screen mesh was established to estimate the cask temperatures.

Thermal Analysis of Concrete Storage Cask with Bird Screen Meshes

International Nuclear Information System (INIS)

Lee, Ju-Chan; Bang, K.S.; Yu, S.H.; Cho, S.S.; Choi, W.S.

2016-01-01

In this study, a thermal analysis of the cask with bird screen meshes has been performed using a porous media model. The overpack consists of a structural material, a concrete shielding, and a ventilation system. Heat is removed from the cask to the environment by a passive means only. Air inlet and outlet ducts are installed at the bottom and top of the cask for a ventilation system. Bird screen meshes are installed at the air inlet and outlet ducts to inhibit intrusion of debris from the external environment. The presence of this screens introduce an additional resistance to air flow through the ducts. Five types of meshes for bird screen were considered in this study. The bird screen meshes at the inlet and outlet vents reduce the open area for flow by about 44 - 79 %. Flow resistance coefficients for porous media model were deduced from the fluid flow analysis of bird screen meshes. Thermal analyses for the concrete cask have been carried out using a porous media model. The analysis results agreed well with the test results. Therefore, it was shown that the porous media model for the screen mesh was established to estimate the cask temperatures

Polyhedral meshing in numerical analysis of conjugate heat transfer

Science.gov (United States)

Sosnowski, Marcin; Krzywanski, Jaroslaw; Grabowska, Karolina; Gnatowska, Renata

2018-06-01

Computational methods have been widely applied in conjugate heat transfer analysis. The very first and crucial step in such research is the meshing process which consists in dividing the analysed geometry into numerous small control volumes (cells). In Computational Fluid Dynamics (CFD) applications it is desirable to use the hexahedral cells as the resulting mesh is characterized by low numerical diffusion. Unfortunately generating such mesh can be a very time-consuming task and in case of complicated geometry - it may not be possible to generate cells of good quality. Therefore tetrahedral cells have been implemented into commercial pre-processors. Their advantage is the ease of its generation even in case of very complex geometry. On the other hand tetrahedrons cannot be stretched excessively without decreasing the mesh quality factor, so significantly larger number of cells has to be used in comparison to hexahedral mesh in order to achieve a reasonable accuracy. Moreover the numerical diffusion of tetrahedral elements is significantly higher. Therefore the polyhedral cells are proposed within the paper in order to combine the advantages of hexahedrons (low numerical diffusion resulting in accurate solution) and tetrahedrons (rapid semi-automatic generation) as well as to overcome the disadvantages of both the above mentioned mesh types. The major benefit of polyhedral mesh is that each individual cell has many neighbours, so gradients can be well approximated. Polyhedrons are also less sensitive to stretching than tetrahedrons which results in better mesh quality leading to improved numerical stability of the model. In addition, numerical diffusion is reduced due to mass exchange over numerous faces. This leads to a more accurate solution achieved with a lower cell count. Therefore detailed comparison of numerical modelling results concerning conjugate heat transfer using tetrahedral and polyhedral meshes is presented in the paper.

A Novel Mesh Quality Improvement Method for Boundary Elements

Directory of Open Access Journals (Sweden)

Hou-lin Liu

2012-01-01

Full Text Available In order to improve the boundary mesh quality while maintaining the essential characteristics of discrete surfaces, a new approach combining optimization-based smoothing and topology optimization is developed. The smoothing objective function is modified, in which two functions denoting boundary and interior quality, respectively, and a weight coefficient controlling boundary quality are taken into account. In addition, the existing smoothing algorithm can improve the mesh quality only by repositioning vertices of the interior mesh. Without destroying boundary conformity, bad elements with all their vertices on the boundary cannot be eliminated. Then, topology optimization is employed, and those elements are converted into other types of elements whose quality can be improved by smoothing. The practical application shows that the worst elements can be eliminated and, with the increase of weight coefficient, the average quality of boundary mesh can also be improved. Results obtained with the combined approach are compared with some common approach. It is clearly shown that it performs better than the existing approach.

Early experience with mesh excision for adverse outcomes after transvaginal mesh placement using prolapse kits.

Science.gov (United States)

Ridgeway, Beri; Walters, Mark D; Paraiso, Marie Fidela R; Barber, Matthew D; McAchran, Sarah E; Goldman, Howard B; Jelovsek, J Eric

2008-12-01

The purpose of this study was to determine the complications, treatments, and outcomes in patients choosing to undergo removal of mesh previously placed with a mesh procedural kit. This was a retrospective review of all patients who underwent surgical removal of transvaginal mesh for mesh-related complications during a 3-year period at Cleveland Clinic. At last follow-up, patients reported degree of pain, level of improvement, sexual activity, and continued symptoms. Nineteen patients underwent removal of mesh during the study period. Indications for removal included chronic pain (6/19), dyspareunia (6/19), recurrent pelvic organ prolapse (8/19), mesh erosion (12/19), and vesicovaginal fistula (3/19), with most patients (16/19) citing more than 1 reason. There were few complications related to the mesh removal. Most patients reported significant relief of symptoms. Mesh removal can be technically difficult but appears to be safe with few complications and high relief of symptoms, although some symptoms can persist.

Mesh erosion after abdominal sacrocolpopexy.

Science.gov (United States)

Kohli, N; Walsh, P M; Roat, T W; Karram, M M

1998-12-01

To report our experience with erosion of permanent suture or mesh material after abdominal sacrocolpopexy. A retrospective chart review was performed to identify patients who underwent sacrocolpopexy by the same surgeon over 8 years. Demographic data, operative notes, hospital records, and office charts were reviewed after sacrocolpopexy. Patients with erosion of either suture or mesh were treated initially with conservative therapy followed by surgical intervention as required. Fifty-seven patients underwent sacrocolpopexy using synthetic mesh during the study period. The mean (range) postoperative follow-up was 19.9 (1.3-50) months. Seven patients (12%) had erosions after abdominal sacrocolpopexy with two suture erosions and five mesh erosions. Patients with suture erosion were asymptomatic compared with patients with mesh erosion, who presented with vaginal bleeding or discharge. The mean (+/-standard deviation) time to erosion was 14.0+/-7.7 (range 4-24) months. Both patients with suture erosion were treated conservatively with estrogen cream. All five patients with mesh erosion required transvaginal removal of the mesh. Mesh erosion can follow abdominal sacrocolpopexy over a long time, and usually presents as vaginal bleeding or discharge. Although patients with suture erosion can be managed successfully with conservative treatment, patients with mesh erosion require surgical intervention. Transvaginal removal of the mesh with vaginal advancement appears to be an effective treatment in patients failing conservative management.

Surgical management of lower urinary mesh perforation after mid-urethral polypropylene mesh sling: mesh excision, urinary tract reconstruction and concomitant pubovaginal sling with autologous rectus fascia.

Science.gov (United States)

Shah, Ketul; Nikolavsky, Dmitriy; Gilsdorf, Daniel; Flynn, Brian J

2013-12-01

We present our management of lower urinary tract (LUT) mesh perforation after mid-urethral polypropylene mesh sling using a novel combination of surgical techniques including total or near total mesh excision, urinary tract reconstruction, and concomitant pubovaginal sling with autologous rectus fascia in a single operation. We retrospectively reviewed the medical records of 189 patients undergoing transvaginal removal of polypropylene mesh from the lower urinary tract or vagina. The focus of this study is 21 patients with LUT mesh perforation after mid-urethral polypropylene mesh sling. We excluded patients with LUT mesh perforation from prolapse kits (n = 4) or sutures (n = 11), or mesh that was removed because of isolated vaginal wall exposure without concomitant LUT perforation (n = 164). Twenty-one patients underwent surgical removal of mesh through a transvaginal approach or combined transvaginal/abdominal approaches. The location of the perforation was the urethra in 14 and the bladder in 7. The mean follow-up was 22 months. There were no major intraoperative complications. All patients had complete resolution of the mesh complication and the primary symptom. Of the patients with urethral perforation, continence was achieved in 10 out of 14 (71.5 %). Of the patients with bladder perforation, continence was achieved in all 7. Total or near total removal of lower urinary tract (LUT) mesh perforation after mid-urethral polypropylene mesh sling can completely resolve LUT mesh perforation in a single operation. A concomitant pubovaginal sling can be safely performed in efforts to treat existing SUI or avoid future surgery for SUI.

The routine use of prosthetic mesh in austere environments: dogma vs data.

Science.gov (United States)

Kuckelman, John P; Barron, Morgan R; Blair, Kelly; Martin, Matthew J

2016-05-01

Mesh repair has become the standard in adult hernia repairs. Mesh infection is an uncommon but potentially devastating complication. Currently, there is widespread dogma against the use of prosthetic mesh (PM) in deployed or austere environments but little available data to support or refute this bias. Retrospective review of all hernia repairs over 1 year in a forward deployed surgical unit in Afghanistan. Demographics, hernia type, repair performed, and mesh type were evaluated. Follow-up was completed up to 6 weeks and then as needed for up to a year, and complications to include infection were recorded. Sixty-six patients were identified, mean age was 38 (range 3 to 80) and 98% were male. Single-dose perioperative antibiotics and standard sterile technique were used in all cases. The majority (70%) had PM placed. The mean operative time was 54 min, and mean estimated blood loss was less than 25 cm(3). The vast majority of our hernias were inguinal (95%) with 1 ventral and 2 umbilical hernias. In the PM group, there were no surgical site infections, no mesh infections, and no mesh explantation or reoperation. There were no recurrences in either group identified at up to 1-year postoperation. There was no statistically significant difference in any outcome measure between the PM and no-PM groups. The use of PM for hernia repairs in the austere or forward environment appears safe and did not increase the risk of wound infection, mesh infections, or recurrence. Published by Elsevier Inc.

Surface meshing with curvature convergence

KAUST Repository

Li, Huibin; Zeng, Wei; Morvan, Jean-Marie; Chen, Liming; Gu, Xianfengdavid

2014-01-01

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.

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.

Two-dimensional isostatic meshes in the finite element method

OpenAIRE

Martínez Marín, Rubén; Samartín, Avelino

2002-01-01

In a Finite Element (FE) analysis of elastic solids several items are usually considered, namely, type and shape of the elements, number of nodes per element, node positions, FE mesh, total number of degrees of freedom (dot) among others. In this paper a method to improve a given FE mesh used for a particular analysis is described. For the improvement criterion different objective functions have been chosen (Total potential energy and Average quadratic error) and the number of nodes and dof's...

Male infertility after mesh hernia repair: A prospective study.

Science.gov (United States)

Hallén, Magnus; Sandblom, Gabriel; Nordin, Pär; Gunnarsson, Ulf; Kvist, Ulrik; Westerdahl, Johan

2011-02-01

Several animal studies have raised concern about the risk for obstructive azoospermia owing to vasal fibrosis caused by the use of alloplastic mesh prosthesis in inguinal hernia repair. The aim of this study was to determine the prevalence of male infertility after bilateral mesh repair. In a prospective study, a questionnaire inquiring about involuntary childlessness, investigation for infertility and number of children was sent by mail to a group of 376 men aged 18-55 years, who had undergone bilateral mesh repair, identified in the Swedish Hernia Register (SHR). Questionnaires were also sent to 2 control groups, 1 consisting of 186 men from the SHR who had undergone bilateral repair without mesh, and 1 consisting of 383 men identified in the general population. The control group from the SHR was matched 2:1 for age and years elapsed since operation. The control group from the general population was matched 1:1 for age and marital status. The overall response rate was 525 of 945 (56%). Method of approach (anterior or posterior), type of mesh, and testicular status at the time of the repair had no significant impact on the answers to the questions. Nor did subgroup analysis of the men ≤40 years old reveal any significant differences. The results of this prospective study in men do not support the hypothesis that bilateral inguinal hernia repair with alloplastic mesh prosthesis causes male infertility at a significantly greater rate than those operated without mesh. Copyright © 2011 Mosby, Inc. All rights reserved.

3D visualization and finite element mesh formation from wood anatomy samples, Part II – Algorithm approach

Directory of Open Access Journals (Sweden)

Petr Koňas

2009-01-01

Full Text Available Paper presents new original application WOOD3D in form of program code assembling. The work extends the previous article “Part I – Theoretical approach” in detail description of implemented C++ classes of utilized projects Visualization Toolkit (VTK, Insight Toolkit (ITK and MIMX. Code is written in CMake style and it is available as multiplatform application. Currently GNU Linux (32/64b and MS Windows (32/64b platforms were released. Article discusses various filter classes for image filtering. Mainly Otsu and Binary threshold filters are classified for anatomy wood samples thresholding. Registration of images series is emphasized for difference of colour spaces compensation is included. Resulted work flow of image analysis is new methodological approach for images processing through the composition, visualization, filtering, registration and finite element mesh formation. Application generates script in ANSYS parametric design language (APDL which is fully compatible with ANSYS finite element solver and designer environment. The script includes the whole definition of unstructured finite element mesh formed by individual elements and nodes. Due to simple notation, the same script can be used for generation of geometrical entities in element positions. Such formed volumetric entities are prepared for further geometry approximation (e.g. by boolean or more advanced methods. Hexahedral and tetrahedral types of mesh elements are formed on user request with specified mesh options. Hexahedral meshes are formed both with uniform element size and with anisotropic character. Modified octree method for hexahedral mesh with anisotropic character was declared in application. Multicore CPUs in the application are supported for fast image analysis realization. Visualization of image series and consequent 3D image are realized in VTK format sufficiently known and public format, visualized in GPL application Paraview. Future work based on mesh

The Availability of MeSH in Vendor-Supplied Cataloguing Records, as Seen Through the Catalogue of a Canadian Academic Health Library

Directory of Open Access Journals (Sweden)

Pamela S. Morgan

2007-09-01

Full Text Available This study examines the prevalence of medical subject headings in vendor-supplied cataloguing records for publications contained within aggregated databases or publisher collections. In the first phase, the catalogue of one Canadian academic medical library was examined to determine the extent to which medical subject headings (MeSH are available in the vendor-supplied records. In the second phase, these results were compared to the catalogues of other Canadian academic medical libraries in order to reach a generalization regarding the availability of MeSH headings for electronic resources. MeSH was more widespread in records for electronic journals but was noticeably lacking in records for electronic monographs, and for Canadian publications. There is no standard for ensuring MeSH are assigned to monograph records for health titles and there is no library in Canada with responsibility for ensuring that Canadian health publications receive Medical Subject Headings. It is incumbent upon libraries using MeSH to ensure that vendors are aware of this need when purchasing record sets.

Voltammetry at micro-mesh electrodes

Directory of Open Access Journals (Sweden)

Wadhawan Jay D.

2003-01-01

Full Text Available The voltammetry at three micro-mesh electrodes is explored. It is found that at sufficiently short experimental durations, the micro-mesh working electrode first behaves as an ensemble of microband electrodes, then follows the behaviour anticipated for an array of diffusion-independent micro-ring electrodes of the same perimeter as individual grid-squares within the mesh. During prolonged electrolysis, the micro-mesh electrode follows that behaviour anticipated theoretically for a cubically-packed partially-blocked electrode. Application of the micro-mesh electrode for the electrochemical determination of carbon dioxide in DMSO electrolyte solutions is further illustrated.

Streaming simplification of tetrahedral meshes.

Science.gov (United States)

Vo, Huy T; Callahan, Steven P; Lindstrom, Peter; Pascucci, Valerio; Silva, Cláudio T

2007-01-01

Unstructured tetrahedral meshes are commonly used in scientific computing to represent scalar, vector, and tensor fields in three dimensions. Visualization of these meshes can be difficult to perform interactively due to their size and complexity. By reducing the size of the data, we can accomplish real-time visualization necessary for scientific analysis. We propose a two-step approach for streaming simplification of large tetrahedral meshes. Our algorithm arranges the data on disk in a streaming, I/O-efficient format that allows coherent access to the tetrahedral cells. A quadric-based simplification is sequentially performed on small portions of the mesh in-core. Our output is a coherent streaming mesh which facilitates future processing. Our technique is fast, produces high quality approximations, and operates out-of-core to process meshes too large for main memory.

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.

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.

Laparoscopic mesh explantation and drainage of sacral abscess remote from transvaginal excision of exposed sacral colpopexy mesh.

Science.gov (United States)

Roth, Ted M; Reight, Ian

2012-07-01

Sacral colpopexy may be complicated by mesh exposure, and the surgical treatment of mesh exposure typically results in minor postoperative morbidity and few delayed complications. A 75-year-old woman presented 7 years after a laparoscopic sacral colpopexy, with Mersilene mesh, with an apical mesh exposure. She underwent an uncomplicated transvaginal excision and was asymptomatic until 8 months later when she presented with vaginal drainage and a sacral abscess. This was successfully treated with laparoscopic enterolysis, drainage of the abscess, and explantation of the remaining mesh. Incomplete excision of exposed colpopexy mesh can lead to ascending infection and sacral abscess. Laparoscopic drainage and mesh removal may be considered in these patients.

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

KAUST Repository

Zhang, Fang; Merrill, Matthew D.; Tokash, Justin C.; Saito, Tomonori; Cheng, Shaoan; Hickner, Michael A.; Logan, Bruce E.

2011-01-01

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

SUPERIMPOSED MESH PLOTTING IN MCNP

Energy Technology Data Exchange (ETDEWEB)

J. HENDRICKS

2001-02-01

The capability to plot superimposed meshes has been added to MCNP{trademark}. MCNP4C featured a superimposed mesh weight window generator which enabled users to set up geometries without having to subdivide geometric cells for variance reduction. The variance reduction was performed with weight windows on a rectangular or cylindrical mesh superimposed over the physical geometry. Experience with the new capability was favorable but also indicated that a number of enhancements would be very beneficial, particularly a means of visualizing the mesh and its values. The mathematics for plotting the mesh and its values is described here along with a description of other upgrades.

Cache-Oblivious Mesh Layouts

International Nuclear Information System (INIS)

Yoon, S; Lindstrom, P; Pascucci, V; Manocha, D

2005-01-01

We present a novel method for computing cache-oblivious layouts of large meshes that improve the performance of interactive visualization and geometric processing algorithms. Given that the mesh is accessed in a reasonably coherent manner, we assume no particular data access patterns or cache parameters of the memory hierarchy involved in the computation. Furthermore, our formulation extends directly to computing layouts of multi-resolution and bounding volume hierarchies of large meshes. We develop a simple and practical cache-oblivious metric for estimating cache misses. Computing a coherent mesh layout is reduced to a combinatorial optimization problem. We designed and implemented an out-of-core multilevel minimization algorithm and tested its performance on unstructured meshes composed of tens to hundreds of millions of triangles. Our layouts can significantly reduce the number of cache misses. We have observed 2-20 times speedups in view-dependent rendering, collision detection, and isocontour extraction without any modification of the algorithms or runtime applications

Anisotropic evaluation of synthetic surgical meshes.

Science.gov (United States)

Saberski, E R; Orenstein, S B; Novitsky, Y W

2011-02-01

The material properties of meshes used in hernia repair contribute to the overall mechanical behavior of the repair. The anisotropic potential of synthetic meshes, representing a difference in material properties (e.g., elasticity) in different material axes, is not well defined to date. Haphazard orientation of anisotropic mesh material can contribute to inconsistent surgical outcomes. We aimed to characterize and compare anisotropic properties of commonly used synthetic meshes. Six different polypropylene (Trelex(®), ProLite™, Ultrapro™), polyester (Parietex™), and PTFE-based (Dualmesh(®), Infinit) synthetic meshes were selected. Longitudinal and transverse axes were defined for each mesh, and samples were cut in each axis orientation. Samples underwent uniaxial tensile testing, from which the elastic modulus (E) in each axis was determined. The degree of anisotropy (λ) was calculated as a logarithmic expression of the ratio between the elastic modulus in each axis. Five of six meshes displayed significant anisotropic behavior. Ultrapro™ and Infinit exhibited approximately 12- and 20-fold differences between perpendicular axes, respectively. Trelex(®), ProLite™, and Parietex™ were 2.3-2.4 times. Dualmesh(®) was the least anisotropic mesh, without marked difference between the axes. Anisotropy of synthetic meshes has been underappreciated. In this study, we found striking differences between elastic properties of perpendicular axes for most commonly used synthetic meshes. Indiscriminate orientation of anisotropic mesh may adversely affect hernia repairs. Proper labeling of all implants by manufacturers should be mandatory. Understanding the specific anisotropic behavior of synthetic meshes should allow surgeons to employ rational implant orientation to maximize outcomes of hernia repair.

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.

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

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.

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.

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

Science.gov (United States)

Dällenbach, Patrick

2015-01-01

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 clarify the risks, benefits, and the recognized indications for its use. PMID:25848324

Mesh refinement of simulation with the AID riser transmission gamma

International Nuclear Information System (INIS)

Lima Filho, Hilario J.B. de; Benachour, Mohand; Dantas, Carlos C.; Brito, Marcio F.P.; Santos, Valdemir A. dos

2013-01-01

Type reactors Circulating Fluidized Bed (CFBR) vertical, in which the particulate and gaseous phases have flows upward (riser) have been widely used in gasification processes, combustion and fluid catalytic cracking (FCC). These biphasic reactors (gas-solid) efficiency depends largely on their hydrodynamic characteristics, and shows different behaviors in the axial and radial directions. The solids axial distribution is observed by the higher concentration in the base, getting more diluted toward the top. Radially, the solids concentration is characterized as core-annular, in which the central region is highly diluted, consisting of dispersed particles and fluid. In the present work developed a two-dimensional geometry (2D) techniques through simulations in computational fluid dynamics (CFD) to predict the gas-solid flow in the riser type CFBR through transient modeling, based on the kinetic theory of granular flow . The refinement of computational meshes provide larger amounts of information on the parameters studied, but may increase the processing time of the simulations. A minimum number of cells applied to the mesh construction was obtained by testing five meshes. The validation of the hydrodynamic parameters was performed using a range of 241Am source and detector NaI (Tl). The numerical results were provided consistent with the experimental data, indicating that the refined computational mesh in a controlled manner, improve the approximation of the expected results. (author)

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.

Properties of meshes used in hernia repair: a comprehensive review of synthetic and biologic meshes.

Science.gov (United States)

Ibrahim, Ahmed M S; Vargas, Christina R; Colakoglu, Salih; Nguyen, John T; Lin, Samuel J; Lee, Bernard T

2015-02-01

Data on the mechanical properties of the adult human abdominal wall have been difficult to obtain rendering manufacture of the ideal mesh for ventral hernia repair a challenge. An ideal mesh would need to exhibit greater biomechanical strength and elasticity than that of the abdominal wall. The aim of this study is to quantitatively compare the biomechanical properties of the most commonly used synthetic and biologic meshes in ventral hernia repair and presents a comprehensive literature review. A narrative review of the literature was performed using the PubMed database spanning articles from 1982 to 2012 including a review of company Web sites to identify all available information relating to the biomechanical properties of various synthetic and biologic meshes used in ventral hernia repair. There exist differences in the mechanical properties and the chemical nature of different meshes. In general, most synthetic materials have greater stiffness and elasticity than what is required for abdominal wall reconstruction; however, each exhibits unique properties that may be beneficial for clinical use. On the contrary, biologic meshes are more elastic but less stiff and with a lower tensile strength than their synthetic counterparts. The current standard of practice for the treatment of ventral hernias is the use of permanent synthetic mesh material. Recently, biologic meshes have become more frequently used. Most meshes exhibit biomechanical properties over the known abdominal wall thresholds. Augmenting strength requires increasing amounts of material contributing to more stiffness and foreign body reaction, which is not necessarily an advantage. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Sierra toolkit computational mesh conceptual model

International Nuclear Information System (INIS)

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

2010-01-01

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.

Outcome of transvaginal mesh and tape removed for pain only.

Science.gov (United States)

Hou, Jack C; Alhalabi, Feras; Lemack, Gary E; Zimmern, Philippe E

2014-09-01

Because there is reluctance to operate for pain, we evaluated midterm outcomes of vaginal mesh and synthetic suburethral tape removed for pain as the only indication. After receiving institutional review board approval we reviewed a prospective database of women without a neurogenic condition who underwent surgery for vaginal mesh or suburethral tape removal with a focus on pain as the single reason for removal and a minimum 6-month followup. The primary outcome was pain level assessed by a visual analog scale (range 0 to 10) at baseline and at each subsequent visit with the score at the last visit used for analysis. Parameters evaluated included demographics, mean time to presentation and type of mesh or tape inserted. From 2005 to 2013, 123 patients underwent surgical removal of mesh (69) and suburethral tape (54) with pain as the only indication. Mean followup was 35 months (range 6 to 59) in the tape group and 22 months (range 6 to 47) in the mesh group. The visual analog scale score decreased from a mean preoperative level of 7.9 to 0.9 postoperatively (p = 0.0014) in the mesh group and from 5.3 to 1.5 (p = 0.00074) in the tape group. Pain-free status, considered a score of 0, was achieved in 81% of tape and 67% of mesh cases, respectively. No statistically significant difference was found between the groups. When pain is the only indication for suburethral tape or vaginal mesh removal, a significant decrease in the pain score can be durably expected after removal in most patients at midterm followup. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

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.

Transvaginal mesh kits--how "serious" are the complications and are they reversible?

Science.gov (United States)

Lee, Dominic; Dillon, Benjamin; Lemack, Gary; Gomelsky, Alex; Zimmern, Philippe

2013-01-01

To review the merit of the U.S. Food and Drug Administration-issued warnings on the use of transvaginal mesh in women with pelvic organ prolapse because of escalating complications. On institutional review board approval, we reviewed the data from 2 tertiary institutions managing complications of transvaginal mesh. The data recorded included mesh type, details of surgical removal, and patient-reported clinical outcomes. From 2006 to March 2011, 58 women were evaluated. Their mean age was 54.6 years (range 32-80), with a mean follow-up of 13 months (range 6-67). The mean interval to mesh excision surgery from the original prolapse surgery was 21 months (range 2-60). Of the 58 women, 35 (60%) had undergone concurrent midurethral sling surgery with the transvaginal mesh surgery. Also, 21 of the 58 patients (36%) had undergone initial mesh removal attempts before their referral to either tertiary institution. Most women presented with multiple complaints, with mesh extrusion the most frequently reported (n=43 [74%]). Of the 58 women, 17 (29%) required re-excision of residual mesh, 13 once and 4 twice. Five women developed recurrent symptomatic pelvic organ prolapse (7%). The residual rate of dyspareunia and pelvic pain was 14% and 22%, respectively. Fourteen women (24%) were treated successfully, with complete resolution of all presenting symptoms. As outlined in the Food and Drug Administration notifications, patients should be forewarned that some transvaginal mesh complications are life altering and might not always be surgically correctable. Copyright © 2013 Elsevier Inc. All rights reserved.

Evidence for replacement of an infected synthetic by a biological mesh in abdominal wall hernia repair

Directory of Open Access Journals (Sweden)

Agneta eMontgomery

2016-01-01

Full Text Available The incidence of deep infection using a synthetic mesh in inguinal hernia repair is low and reported to be well below 1%. This is in contrast to incisional hernia surgery where the reported incidence is 3% respective 13% comparing laparoscopic to open mesh repair reported in a Cochrane review. Main risk factors were long operation time, surgical site contamination and early wound complications. An infected mesh can be preserved using conservative treatment were negative pressure wound therapy (VAC® could play an important role. If strategy fails, the mesh needs to be removed. This review aims to look at evidence for situations were a biological mesh would work as a replacement of a removed infected synthetic mesh. Material and MethodsA literature search of the Medline database was performed using the PubMed search engine. Twenty publications were found relevant for this review.ResultsFor studies reviewed three options are presented: removal of the infected synthetic mesh alone, replacement with either a new synthetic or a new biological mesh. Operations were all performed at specialist centers. Removal of the mesh alone was an option limited to inguinal hernias. In ventral/incisional hernias the use of a biological mesh for replacement resulted in a very high recurrence rate, if bridging was required. Either a synthetic or a biological mesh seems to work as a replacement when fascial closure can be achieved. Evidence is though very low. ConclusionWhen required, either a synthetic or a biological meshes seems to work as a replacement for an infected synthetic mesh if the defect can be closed. It is however not recommended to use a biological mesh for bridging. Mesh replacement surgery is demanding and is recommended to be performed in a specialist center.

Evaluation on Bending Properties of Biomaterial GUM Metal Meshed Plates for Bone Graft Applications

Science.gov (United States)

Suzuki, Hiromichi; He, Jianmei

2017-11-01

There are three bone graft methods for bone defects caused by diseases such as cancer and accident injuries: Autogenous bone grafts, Allografts and Artificial bone grafts. In this study, meshed GUM Metal plates with lower elasticity, high strength and high biocompatibility are introduced to solve the over stiffness & weight problems of ready-used metal implants. Basic mesh shapes are designed and applied to GUM Metal plates using 3D CAD modeling tools. Bending properties of prototype meshed GUM Metal plates are evaluated experimentally and analytically. Meshed plate specimens with 180°, 120° and 60° axis-symmetrical types were fabricated for 3-point bending tests. The pseudo bending elastic moduli of meshed plate specimens obtained from 3-point bending test are ranged from 4.22 GPa to 16.07 GPa, within the elasticity range of natural cortical bones from 2.0 GPa to 30.0 GPa. Analytical approach method is validated by comparison with experimental and analytical results for evaluation on bending property of meshed plates.

Coarse mesh code development

Energy Technology Data Exchange (ETDEWEB)

Lieberoth, J.

1975-06-15

The numerical solution of the neutron diffusion equation plays a very important role in the analysis of nuclear reactors. A wide variety of numerical procedures has been proposed, at which most of the frequently used numerical methods are fundamentally based on the finite- difference approximation where the partial derivatives are approximated by the finite difference. For complex geometries, typical of the practical reactor problems, the computational accuracy of the finite-difference method is seriously affected by the size of the mesh width relative to the neutron diffusion length and by the heterogeneity of the medium. Thus, a very large number of mesh points are generally required to obtain a reasonably accurate approximate solution of the multi-dimensional diffusion equation. Since the computation time is approximately proportional to the number of mesh points, a detailed multidimensional analysis, based on the conventional finite-difference method, is still expensive even with modern large-scale computers. Accordingly, there is a strong incentive to develop alternatives that can reduce the number of mesh-points and still retain accuracy. One of the promising alternatives is the finite element method, which consists of the expansion of the neutron flux by piecewise polynomials. One of the advantages of this procedure is its flexibility in selecting the locations of the mesh points and the degree of the expansion polynomial. The small number of mesh points of the coarse grid enables to store the results of several of the least outer iterations and to calculate well extrapolated values of them by comfortable formalisms. This holds especially if only one energy distribution of fission neutrons is assumed for all fission processes in the reactor, because the whole information of an outer iteration is contained in a field of fission rates which has the size of all mesh points of the coarse grid.

[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.

Numerical Investigation of Corrugated Wire Mesh Laminate

Directory of Open Access Journals (Sweden)

Jeongho Choi

2013-01-01

Full Text Available The aim of this work is to develop a numerical model of Corrugated Wire Mesh Laminate (CWML capturing all its complexities such as nonlinear material properties, nonlinear geometry and large deformation behaviour, and frictional behaviour. Development of such a model will facilitate numerical simulation of the mechanical behaviour of the wire mesh structure under various types of loading as well as the variation of the CWML configuration parameters to tailor its mechanical properties to suit the intended application. Starting with a single strand truss model consisting of four waves with a bilinear stress-strain model to represent the plastic behaviour of stainless steel, the finite element model is gradually built up to study single-layer structures with 18 strands of corrugated wire meshes consistency and double- and quadruple-layered laminates with alternating crossply orientations. The compressive behaviour of the CWML model is simulated using contact elements to model friction and is compared to the load-deflection behaviour determined experimentally in uniaxial compression tests. The numerical model of the CWML is then employed to conduct the aim of establishing the upper and lower bounds of stiffness and load capacity achievable by such structures.

Incorporation of detailed eye model into polygon-mesh versions of ICRP-110 reference phantoms.

Science.gov (United States)

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

2015-11-21

The dose coefficients for the eye lens reported in ICRP 2010 Publication 116 were calculated using both a stylized model and the ICRP-110 reference phantoms, according to the type of radiation, energy, and irradiation geometry. To maintain consistency of lens dose assessment, in the present study we incorporated the ICRP-116 detailed eye model into the converted polygon-mesh (PM) version of the ICRP-110 reference phantoms. After the incorporation, the dose coefficients for the eye lens were calculated and compared with those of the ICRP-116 data. The results showed generally a good agreement between the newly calculated lens dose coefficients and the values of ICRP 2010 Publication 116. Significant differences were found for some irradiation cases due mainly to the use of different types of phantoms. Considering that the PM version of the ICRP-110 reference phantoms preserve the original topology of the ICRP-110 reference phantoms, it is believed that the PM version phantoms, along with the detailed eye model, provide more reliable and consistent dose coefficients for the eye lens.

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.

Fine--Mesh Photodetectors for CMS Endcap Electromagnetic Calorimeter

CERN Document Server

Bajanov, N A; Golubev, Nikolai; Gusev, Yuri; Kachanov, Vassili; Klechneva, T Y; Kovalev, A I; Levtchenko, L A; Lukyanov, Valery; Mamaeva, Galina; Moroz, Feodor; Prilutskaya, D M; Seliverstov, Dmitry; Blinnikov, Yuri

1998-01-01

The behaviour of fine-mesh vacuum phototetrodes and phototriodes ( VPTs) in an axial magnetic field of ( 0 -- 4)T has been investigated. The measured VPT parameters are: fine-mesh cell dimensions, the photocathode sensitivity and its homogenity, the gain in zero and 4T magnetic field at tilt angles corresponding to the rapidity range of CMS ECAL Endcap 1.479 -- 3.0 and excess noise factor. Measurements have been performed on 21 and 30 mm diameter photodetectors with different fine-mesh structures: 30, 60 and 100 lines per mm under different types of photocathode illumination by green LED. Phototriodes with 30 or 60 lines per mm and an external diameter of 21 mm are found to be the best candidates for the CMS environment with the initial size of PWO crystals proposed to be used in the Endcap, by comparison with phototetrodes. They provide a gain of the order of 6 -- 8 in 4T magnetic field and an excess noise factor of 2 under full photocathode illumination.

Meshes optimized for discrete exterior calculus (DEC).

Energy Technology Data Exchange (ETDEWEB)

Mousley, Sarah C. [Univ. of Illinois, Urbana-Champaign, IL (United States); Deakin, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knupp, Patrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Scott A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

We study the optimization of an energy function used by the meshing community to measure and improve mesh quality. This energy is non-traditional because it is dependent on both the primal triangulation and its dual Voronoi (power) diagram. The energy is a measure of the mesh's quality for usage in Discrete Exterior Calculus (DEC), a method for numerically solving PDEs. In DEC, the PDE domain is triangulated and this mesh is used to obtain discrete approximations of the continuous operators in the PDE. The energy of a mesh gives an upper bound on the error of the discrete diagonal approximation of the Hodge star operator. In practice, one begins with an initial mesh and then makes adjustments to produce a mesh of lower energy. However, we have discovered several shortcomings in directly optimizing this energy, e.g. its non-convexity, and we show that the search for an optimized mesh may lead to mesh inversion (malformed triangles). We propose a new energy function to address some of these issues.

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.

Leveraging the power of mesh

Energy Technology Data Exchange (ETDEWEB)

Glass, H. [Cellnet, Alpharetta, GA (United States)

2006-07-01

Mesh network applications are used by utilities for metering, demand response, and mobile workforce management. This presentation provided an overview of a multi-dimensional mesh application designed to offer improved scalability and higher throughput in advanced metering infrastructure (AMI) systems. Mesh applications can be used in AMI for load balancing and forecasting, as well as for distribution and transmission planning. New revenue opportunities can be realized through the application's ability to improve notification and monitoring services, and customer service communications. Mesh network security features include data encryption, data fragmentation and the automatic re-routing of data. In order to use mesh network applications, networks must have sufficient bandwidth and provide flexibility at the endpoint layer to support multiple devices from multiple vendors, as well as support multiple protocols. It was concluded that smart meters will not enable energy response solutions without an underlying AMI that is reliable, scalable and self-healing. .refs., tabs., figs.

Hernia Surgical Mesh Implants

Science.gov (United States)

... knitted mesh or non-knitted sheet forms. The synthetic materials used can be absorbable, non-absorbable or a combination of absorbable and non-absorbable materials. Animal-derived mesh are made of animal tissue, such as intestine or skin, that has been processed and disinfected to be ...

A THREE-YEAR EXPERIENCE WITH ANTERIOR TRANSOBTURATOR MESH (ATOM AND POSTERIOR ISCHIORECTAL MESH (PIRM

Directory of Open Access Journals (Sweden)

Marijan Lužnik

2018-02-01

Full Text Available Background. Use of alloplastic mesh implantates allow a new urogynecologycal surgical techniques achieve a marked improvement in pelvic organ static and pelvic floor function with minimally invasive needle transvaginal intervention like an anterior transobturator mesh (ATOM and a posterior ischiorectal mesh (PIRM procedures. Methods. In three years, between April 2006 and May 2009, we performed one hundred and eightyfour operative corrections of female pelvic organ prolapse (POP and pelvic floor dysfunction (PFD with mesh implantates. The eighty-three patients with surgical procedure TVT-O or Monarc as solo intervention indicated by stress urinary incontinence without POP, are not included in this number. In 97 % of mesh operations, Gynemesh 10 × 15 cm was used. For correction of anterior vaginal prolapse with ATOM procedure, Gynemesh was individually trimmed in mesh with 6 free arms for tension-free transobturator application and tension-free apical collar. IVS (Intravaginal sling 04 Tunneller (Tyco needle system was used for transobturator application of 6 arms through 4 dermal incisions (2 on right and 2 on left. Minimal anterior median colpotomy was made in two separate parts. For correction of posterior vaginal prolapse with PIRM procedure Gynemesh was trimmed in mesh with 4 free arms and tension-free collar. Two ischiorectal long arms for tension-free application through fossa ischiorectale – right and left, and two short arms for perineal body also on both sides. IVS 02 Tunneller (Tyco needle system was used for tension-free application of 4 arms through 4 dermal incisions (2 on right and 2 on left in PIRM. Results. All 184 procedures were performed relatively safely. In 9 cases of ATOM we had perforation of bladder, in 5 by application of anterior needle, in 3 by application of posterior needle and in one case with pincette when collar was inserted in lateral vesico – vaginal space. In 2 cases of PIRM we had perforation of rectum

Experimental Study Of Fog Water Harvesting By Stainless Steel Mesh

Directory of Open Access Journals (Sweden)

Nikhil R. Pawar

2017-06-01

Full Text Available The collection of fog water is a simple and sustainable technology to get hold of fresh water for various purposes. In areas where a substantial amount of fog can be obtained it is feasible to set up a stainless steel as well as black double layer plastic mesh structure for fog water harvesting. The mesh structure is directly exposed to the weather and the fog containing air is pushed through the active mesh surface by the wind. Afterward fog droplets are deposited on the active mesh area which combines to form superior droplets and run down into a gutter to storage by gravity. Fog water harvesting rates show a discrepancy from site to site. The scope of this experimental work is to review fog collection at SCOE Pune campus and to examine factors of success. This study is to synthesize the understanding of fog water harvesting in the institutional era and to analyze its benefits and boundaries for future development. The rate of fog water harvesting depends on the science of fog physics chemistry and its starring role in the hydrological cycle. This technology runs on zero energy and zeroes pollution level with cost of the benefit. The collected or treated clear water mainly could be used for different purposes as per requirement. For further development this technology public as well as government participation is needed.

Partitioning of unstructured meshes for load balancing

International Nuclear Information System (INIS)

Martin, O.C.; Otto, S.W.

1994-01-01

Many large-scale engineering and scientific calculations involve repeated updating of variables on an unstructured mesh. To do these types of computations on distributed memory parallel computers, it is necessary to partition the mesh among the processors so that the load balance is maximized and inter-processor communication time is minimized. This can be approximated by the problem, of partitioning a graph so as to obtain a minimum cut, a well-studied combinatorial optimization problem. Graph partitioning algorithms are discussed that give good but not necessarily optimum solutions. These algorithms include local search methods recursive spectral bisection, and more general purpose methods such as simulated annealing. It is shown that a general procedure enables to combine simulated annealing with Kernighan-Lin. The resulting algorithm is both very fast and extremely effective. (authors) 23 refs., 3 figs., 1 tab

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.

Comparison of a lightweight polypropylene mesh (Optilene® LP) and a large-pore knitted PTFE mesh (GORE® INFINIT® mesh)--Biocompatibility in a standardized endoscopic extraperitoneal hernia model.

Science.gov (United States)

Jacob, Dietmar A; Schug-Pass, Christine; Sommerer, Florian; Tannapfel, Andrea; Lippert, Hans; Köckerling, Ferdinand

2012-02-01

The use of a mesh with good biocompatibility properties is of decisive importance for the avoidance of recurrences and chronic pain in endoscopic hernia repair surgery. As we know from numerous experiments and clinical experience, large-pore, lightweight polypropylene meshes possess the best biocompatibility. However, large-pore meshes of different polymers may be used as well and might be an alternative solution. Utilizing a totally extraperitoneal technique in an established animal model, 20 domestic pigs were implanted with either a lightweight large-pore polypropylene (PP) mesh (Optilene® LP) or a medium-weight large-pore knitted polytetrafluorethylene (PTFE) mesh (GORE® INFINIT® mesh). After 94 days, the pigs were sacrificed and postmortem diagnostic laparoscopy was performed, followed by explantation of the specimens for macroscopic, histological and immunohistochemical evaluation. The mean mesh shrinkage rate was 14.2% for Optilene® LP vs. 24.7% for INFINIT® mesh (p = 0.017). The partial volume of the inflammatory cells was 11.2% for Optilene® LP vs. 13.9% for INFINIT (n.s.). CD68 was significantly higher for INFINIT (11.8% vs. 5.6%, p = 0.007). The markers of cell turnover, namely Ki67 and the apoptotic index, were comparable at 6.4% vs. 12.4% (n.s.) and 1.6% vs. 2.0% (n.s.). In the extracellular matrix, TGF-β was 35.4% for Optilene® LP and 31.0% for INFINIT® (n.s.). Collagen I (pos/300 μm) deposits were 117.8 and 114.9, respectively. In our experimental examinations, Optilene® LP and INFINIT® showed a comparable biocompatibility in terms of chronic inflammatory reaction; however, the shrinkage rate was significantly higher for INFINIT® after 3 months. The higher shrinkage rate of INFINIT® should be taken into account when choosing the mesh size for an adequate hernia overlap.

Mesh fixation in laparoscopic incisional hernia repair: glue fixation provides attachment strength similar to absorbable tacks but differs substantially in different meshes.

Science.gov (United States)

Rieder, Erwin; Stoiber, Martin; Scheikl, Verena; Poglitsch, Marcus; Dal Borgo, Andrea; Prager, Gerhard; Schima, Heinrich

2011-01-01

Laparoscopic ventral hernia repair has gained popularity among minimally invasive surgeons. However, mesh fixation remains a matter of discussion. This study was designed to compare noninvasive fibrin-glue attachment with tack fixation of meshes developed primarily for intra-abdominal use. It was hypothesized that particular mesh structures would substantially influence detachment force. For initial evaluation, specimens of laminated polypropylene/polydioxanone meshes were anchored to porcine abdominal walls by either helical titanium tacks or absorbable tacks in vitro. A universal tensile-testing machine was used to measure tangential detachment forces (TF). For subsequent experiments of glue fixation, polypropylene/polydioxanone mesh and 4 additional meshes with diverse particular mesh structure, ie, polyvinylidene fluoride/polypropylene mesh, a titanium-coated polypropylene mesh, a polyester mesh bonded with a resorbable collagen, and a macroporous condensed PTFE mesh were evaluated. TF tests revealed that fibrin-glue attachment was not substantially different from that achieved with absorbable tacks (median TF 7.8 Newton [N], range 1.3 to 15.8 N), but only when certain open porous meshes (polyvinylidene fluoride/polypropylene mesh: median 6.2 N, range 3.4 to 10.3 N; titanium-coated polypropylene mesh: median 5.2 N, range 2.1 to 11.7 N) were used. Meshes coated by an anti-adhesive barrier (polypropylene/polydioxanone mesh: median 3.1 N, range 1.7 to 5.8 N; polyester mesh bonded with a resorbable collagen: median 1.3 N, range 0.5 to 1.9 N), or the condensed PTFE mesh (median 3.1 N, range 2.1 to 7.0 N) provided a significantly lower TF (p < 0.01). Fibrin glue appears to be an appealing noninvasive option for mesh fixation in laparoscopic ventral hernia repair, but only if appropriate meshes are used. Glue can also serve as an adjunct to mechanical fixation to reduce the number of invasive tacks. Copyright © 2010 American College of Surgeons. Published by Elsevier

The use of mesh implants in vaginal prolapse surgery: Position ...

African Journals Online (AJOL)

sponsored training have also played a role in the adoption of these new techniques. .... surface area and weight of type 1 polypropylene mesh used in different kits, make ... such as bladder and rectal injury, and further recurrence. Realistic.

Parallel adaptive simulations on unstructured meshes

International Nuclear Information System (INIS)

Shephard, M S; Jansen, K E; Sahni, O; Diachin, L A

2007-01-01

This paper discusses methods being developed by the ITAPS center to support the execution of parallel adaptive simulations on unstructured meshes. The paper first outlines the ITAPS approach to the development of interoperable mesh, geometry and field services to support the needs of SciDAC application in these areas. The paper then demonstrates the ability of unstructured adaptive meshing methods built on such interoperable services to effectively solve important physics problems. Attention is then focused on ITAPs' developing ability to solve adaptive unstructured mesh problems on massively parallel computers

SLIC: an interactive mesh generator for finite element and finite difference application programs

International Nuclear Information System (INIS)

Gerhard, M.A.; Greenlaw, R.C.

1979-01-01

Computers with extended memory, such as the CDC STAR 100 and the CRAY 1 with mega-word capacities, are greatly enlarging the size of finite element problems which can be solved. The cost of developing and testing large meshes can be prohibitive unless one uses a computer program for mesh generation and plotting. SLIC is an interactive mesh program which builds and plots 2- and 3-D continuum meshes from interactive terminal or disc input. The user inputs coordinates for certain key points and enters commands which complete the description of the geometry. Entire surfaces and volumes are then generated from the geometric skeleton. SLIC allows the user to correct input errors and saves the corrected command list for later reuse. The mesh can be plotted on a video display at any stage of development to evaluate the work in progress. Output is in the form of an input file to a user-selected computer code. Among the available output types are ADINA, SAP4, and NIKE2D. 11 figures

Prolapse Recurrence after Transvaginal Mesh Removal.

Science.gov (United States)

Rawlings, Tanner; Lavelle, Rebecca S; Coskun, Burhan; Alhalabi, Feras; Zimmern, Philippe E

2015-11-01

We determined the rate of pelvic organ prolapse recurrence after transvaginal mesh removal. Following institutional review board approval a longitudinally collected database of women undergoing transvaginal mesh removal for complications after transvaginal mesh placement with at least 1 year minimum followup was queried for pelvic organ prolapse recurrence. Recurrent prolapse was defined as greater than stage 1 on examination or the need for reoperation at the site of transvaginal mesh removal. Outcome measures were based on POP-Q (Pelvic Organ Prolapse Quantification System) at the last visit. Patients were grouped into 3 groups, including group 1--recurrent prolapse in the same compartment as transvaginal mesh removal, 2--persistent prolapse and 3--prolapse in a compartment different than transvaginal mesh removal. Of 73 women 52 met study inclusion criteria from 2007 to 2013, including 73% who presented with multiple indications for transvaginal mesh removal. The mean interval between insertion and removal was 45 months (range 10 to 165). Overall mean followup after transvaginal mesh removal was 30 months (range 12 to 84). In group 1 (recurrent prolapse) the rate was 15% (6 of 40 patients). Four women underwent surgery for recurrent prolapse at a mean 7 of months (range 5 to 10). Two patients elected observation. The rate of persistent prolapse (group 2) was 23% (12 of 52 patients). Three women underwent prolapse reoperation at a mean of 10 months (range 8 to 12). In group 3 (de novo/different compartment prolapse) the rate was 6% (3 of 52 patients). One woman underwent surgical repair at 52 months. At a mean 2.5-year followup 62% of patients (32 of 52) did not have recurrent or persistent prolapse after transvaginal mesh removal and 85% (44 of 52) did not undergo any further procedure for prolapse. Specifically for pelvic organ prolapse in the same compartment as transvaginal mesh removal 12% of patients had recurrence, of whom 8% underwent prolapse repair

Automatic mesh generation with QMESH program

International Nuclear Information System (INIS)

Ise, Takeharu; Tsutsui, Tsuneo

1977-05-01

Usage of the two-dimensional self-organizing mesh generation program, QMESH, is presented together with the descriptions and the experience, as it has recently been converted and reconstructed from the NEACPL version to the FACOM. The program package consists of the QMESH code to generate quadrilaterial meshes with smoothing techniques, the QPLOT code to plot the data obtained from the QMESH on the graphic COM, and the RENUM code to renumber the meshes by using a bandwidth minimization procedure. The technique of mesh reconstructuring coupled with smoothing techniques is especially useful when one generates the meshes for computer codes based on the finite element method. Several typical examples are given for easy access to the QMESH program, which is registered in the R.B-disks of JAERI for users. (auth.)

3D visualization and finite element mesh formation from wood anatomy samples, Part I – Theoretical approach

Directory of Open Access Journals (Sweden)

Petr Koňas

2009-01-01

Full Text Available The work summarizes created algorithms for formation of finite element (FE mesh which is derived from bitmap pattern. Process of registration, segmentation and meshing is described in detail. C++ library of STL from Insight Toolkit (ITK Project together with Visualization Toolkit (VTK were used for base processing of images. Several methods for appropriate mesh output are discussed. Multiplatform application WOOD3D for the task under GNU GPL license was assembled. Several methods of segmentation and mainly different ways of contouring were included. Tetrahedral and rectilinear types of mesh were programmed. Improving of mesh quality in some simple ways is mentioned. Testing and verification of final program on wood anatomy samples of spruce and walnut was realized. Methods of microscopic anatomy samples preparation are depicted. Final utilization of formed mesh in the simple structural analysis was performed.The article discusses main problems in image analysis due to incompatible colour spaces, samples preparation, thresholding and final conversion into finite element mesh. Assembling of mentioned tasks together and evaluation of the application are main original results of the presented work. In presented program two thresholding filters were used. By utilization of ITK two following filters were included. Otsu filter based and binary filter based were used. The most problematic task occurred in a production of wood anatomy samples in the unique light conditions with minimal or zero co­lour space shift and the following appropriate definition of thresholds (corresponding thresholding parameters and connected methods (prefiltering + registration which influence the continuity and mainly separation of wood anatomy structure. Solution in samples staining is suggested with the following quick image analysis realization. Next original result of the work is complex fully automated application which offers three types of finite element mesh

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.

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

KAUST Repository

Yu, Guojun; Yu, Bo; Sun, Shuyu; Tao, Wenquan

2012-01-01

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.

Polymer microfiber meshes facilitate cardiac differentiation of c-kit{sup +} human cardiac stem cells

Energy Technology Data Exchange (ETDEWEB)

Kan, Lijuan [Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (United States); Thayer, Patrick [Department of Chemical Engineering, School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA (United States); Fan, Huimin [Research Institute of Heart Failure, Shanghai East Hospital of Tongji University, Shanghai (China); Ledford, Benjamin; Chen, Miao [Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (United States); Goldstein, Aaron [Department of Chemical Engineering, School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA (United States); Cao, Guohua [School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA (United States); He, Jia-Qiang, E-mail: jiahe@vt.edu [Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (United States)

2016-09-10

Electrospun microfiber meshes have been shown to support the proliferation and differentiation of many types of stem cells, but the phenotypic fate of c-kit{sup +} human cardiac stem cells (hCSCs) have not been explored. To this end, we utilized thin (~5 µm) elastomeric meshes consisting of aligned 1.7 µm diameter poly (ester-urethane urea) microfibers as substrates to examine their effect on hCSC viability, morphology, proliferation, and differentiation relative to cells cultured on tissue culture polystyrene (TCPS). The results showed that cells on microfiber meshes displayed an elongated morphology aligned in the direction of fiber orientation, lower proliferation rates, but increased expressions of genes and proteins majorly associated with cardiomyocyte phenotype. The early (NK2 homeobox 5, Nkx2.5) and late (cardiac troponin I, cTnI) cardiomyocyte genes were significantly increased on meshes (Nkx=2.5 56.2±13.0, cTnl=2.9±0.56,) over TCPS (Nkx2.5=4.2±0.9, cTnl=1.6±0.5, n=9, p<0.05 for both groups) after differentiation. In contrast, expressions of smooth muscle markers, Gata6 and myosin heavy chain (SM-MHC), were decreased on meshes. Immunocytochemical analysis with cardiac antibody exhibited the similar pattern of above cardiac differentiation. We conclude that aligned microfiber meshes are suitable for guiding cardiac differentiation of hCSCs and may facilitate stem cell-based therapies for treatment of cardiac diseases. - Highlights: • First study to characterize c-kit{sup +} human cardiac stem cells on microfiber meshes. • Microfiber meshes seem reducing cell proliferation, but no effect on cell viability. • Microfiber meshes facilitate the elongation of human cardiac stem cells in culture. • Cardiac but not smooth muscle differentiation were enhanced on microfiber meshes. • Microfiber meshes may be used as cardiac patches in cell-based cardiac therapy.

Refficientlib: an efficient load-rebalanced adaptive mesh refinement algorithm for high-performance computational physics meshes

OpenAIRE

Baiges Aznar, Joan; Bayona Roa, Camilo Andrés

2017-01-01

No separate or additional fees are collected for access to or distribution of the work. In this paper we present a novel algorithm for adaptive mesh refinement in computational physics meshes in a distributed memory parallel setting. The proposed method is developed for nodally based parallel domain partitions where the nodes of the mesh belong to a single processor, whereas the elements can belong to multiple processors. Some of the main features of the algorithm presented in this paper a...

Surgical excision of eroded mesh after prior abdominal sacrocolpopexy.

Science.gov (United States)

South, Mary M T; Foster, Raymond T; Webster, George D; Weidner, Alison C; Amundsen, Cindy L

2007-12-01

We previously described an endoscopic-assisted transvaginal mesh excision technique. This study compares surgical outcomes after transvaginal mesh excision vs endoscopic-assisted transvaginal mesh excision. In addition, we reviewed our postoperative outcomes with excision via laparotomy. This was an inclusive retrospective analysis of patients presenting to our institution from 1997 to 2006 for surgical management of vaginal erosion of permanent mesh after sacrocolpopexy. Three techniques were utilized: transvaginal, endoscopic-assisted transvaginal, and laparotomy. For the patients undergoing transvaginal excision, data recorded included number and type of excisions performed, number of prior excisions performed at outside facilities, intraoperative and postoperative complications (including blood transfusions, pelvic abscess, or bowel complications), use of postoperative antibiotics, persistent symptoms of vaginal bleeding and discharge at follow-up, and demographic characteristics. The intraoperative and postoperative complications and the postoperative symptoms were recorded for the laparotomy cases. Thirty-one patients underwent transvaginal mesh excision during this time period: 17 endoscopic-assisted transvaginal and 14 transvaginal without endoscope assistance. In addition, a total of 7 patients underwent abdominal excision via laparotomy. Comparison of the 2 vaginal methods revealed no difference in the demographics or success rate, with success defined as no symptoms at follow-up. Endoscopic-assisted transvaginal excision was successful in 7 of 17 patients and transvaginal without endoscopic assistance in 9 of 13 patients (1 patient excluded for lack of follow-up data) for a total vaginal success rate of 53.3%. No intraoperative and only minor postoperative complications occurred with either vaginal method. Three patients underwent 3 vaginal attempts to achieve complete symptom resolution. The average follow-up time for the entire vaginal group was 14

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.

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.

Comparison of Absorbable Mesh Plate versus Titanium-Dynamic Mesh Plate in Reconstruction of Blow-Out Fracture: An Analysis of Long-Term Outcomes

Directory of Open Access Journals (Sweden)

Woon Il Baek

2014-07-01

Full Text Available Background A blow-out fracture is one of the most common facial injuries in midface trauma. Orbital wall reconstruction is extremely important because it can cause various functional and aesthetic sequelae. Although many materials are available, there are no uniformly accepted guidelines regarding material selection for orbital wall reconstruction. Methods From January 2007 to August 2012, a total of 78 patients with blow-out fractures were analyzed. 36 patients received absorbable mesh plates, and 42 patients received titanium-dynamic mesh plates. Both groups were retrospectively evaluated for therapeutic efficacy and safety according to the incidence of three different complications: enophthalmos, extraocular movement impairment, and diplopia. Results For all groups (inferior wall fracture group, medial wall fractrue group, and combined inferomedial wall fracture group, there were improvements in the incidence of each complication regardless of implant types. Moreover, a significant improvement of enophthalmos occurred for both types of implants in group 1 (inferior wall fracture group. However, we found no statistically significant differences of efficacy or complication rate in every groups between both implant types. Conclusions Both types of implants showed good results without significant differences in long-term follow up, even though we expected the higher recurrent enophthalmos rate in patients with absorbable plate. In conclusion, both types seem to be equally effective and safe for orbital wall reconstruction. In particular, both implant types significantly improve the incidence of enophthalmos in cases of inferior orbital wall fractures.

The Role of Vaginal Mesh Procedures in Pelvic Organ Prolapse Surgery in View of Complication Risk

Directory of Open Access Journals (Sweden)

David R. Ellington

2013-01-01

Full Text Available Synthetic transvaginal mesh has been employed in the treatment of pelvic organ prolapse for more than a decade. As the use of these devices increased during this period so did adverse event reporting. In 2008, the Food and Drug Administration (FDA Public Health Notification informed physicians and patients of rising concerns with the use of synthetic transvaginal mesh. Shortly thereafter and in parallel to marked increases in adverse event reporting within the Manufacturer and User Device Experience (MAUDE, the FDA released a Safety Communication regarding urogynecologic surgical mesh use. Following this report and in the wake of increased medical industry product withdrawal, growing medicolegal concerns, patient safety, and clinical practice controversy, many gynecologists and pelvic reconstructive surgeons are left with limited long-term data, clinical guidance, and growing uncertainty regarding the role of synthetic transvaginal mesh use in pelvic organ prolapse. This paper reviews the reported complications of synthetic transvaginal mesh with an evidence-based approach as well as providing suggested guidance for the future role of its use amidst the controversy.

The Role of Vaginal Mesh Procedures in Pelvic Organ Prolapse Surgery in View of Complication Risk

Science.gov (United States)

Ellington, David R.; Richter, Holly E.

2013-01-01

Synthetic transvaginal mesh has been employed in the treatment of pelvic organ prolapse for more than a decade. As the use of these devices increased during this period so did adverse event reporting. In 2008, the Food and Drug Administration (FDA) Public Health Notification informed physicians and patients of rising concerns with the use of synthetic transvaginal mesh. Shortly thereafter and in parallel to marked increases in adverse event reporting within the Manufacturer and User Device Experience (MAUDE), the FDA released a Safety Communication regarding urogynecologic surgical mesh use. Following this report and in the wake of increased medical industry product withdrawal, growing medicolegal concerns, patient safety, and clinical practice controversy, many gynecologists and pelvic reconstructive surgeons are left with limited long-term data, clinical guidance, and growing uncertainty regarding the role of synthetic transvaginal mesh use in pelvic organ prolapse. This paper reviews the reported complications of synthetic transvaginal mesh with an evidence-based approach as well as providing suggested guidance for the future role of its use amidst the controversy. PMID:24069035

Outcomes of Autologous Fascia Pubovaginal Sling for Patients with Transvaginal Mesh Related Complications Requiring Mesh Removal.

Science.gov (United States)

McCoy, Olugbemisola; Vaughan, Taylor; Nickles, S Walker; Ashley, Matt; MacLachlan, Lara S; Ginsberg, David; Rovner, Eric

2016-08-01

We reviewed the outcomes of the autologous fascial pubovaginal sling as a salvage procedure for recurrent stress incontinence after intervention for polypropylene mesh erosion/exposure and/or bladder outlet obstruction in patients treated with prior transvaginal synthetic mesh for stress urinary incontinence. In a review of surgical databases at 2 institutions between January 2007 and June 2013 we identified 46 patients who underwent autologous fascial pubovaginal sling following removal of transvaginal synthetic mesh in simultaneous or staged fashion. This cohort of patients was evaluated for outcomes, including subjective and objective success, change in quality of life and complications between those who underwent staged vs concomitant synthetic mesh removal with autologous fascial pubovaginal sling placement. All 46 patients had received at least 1 prior mesh sling for incontinence and 8 (17%) had received prior transvaginal polypropylene mesh for pelvic organ prolapse repair. A total of 30 patients underwent concomitant mesh incision with or without partial excision and autologous sling placement while 16 underwent staged autologous sling placement. Mean followup was 16 months. Of the patients 22% required a mean of 1.8 subsequent interventions an average of 6.5 months after autologous sling placement with no difference in median quality of life at final followup. At last followup 42 of 46 patients (91%) and 35 of 46 (76%) had achieved objective and subjective success, respectively. There was no difference in subjective success between patients treated with a staged vs a concomitant approach (69% vs 80%, p = 0.48). Autologous fascial pubovaginal sling placement after synthetic mesh removal can be performed successfully in patients with stress urinary incontinence as a single or staged procedure. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

The utilization of mesh meteorological data maps for agricultural activity in hilly and mountainous area

International Nuclear Information System (INIS)

Ueyama, H.

2008-01-01

Hilly and mountainous areas occupy approximately 70% of Japan, and the area of farmland in these regions is decreasing; these areas are defined as those from the outer plains to the mountains. The development of strategies for the revitalization of local agriculture in hilly and mountainous areas is therefore a significant problem in Japan. Systematic agriculture is efficient in hilly and mountainous areas, and distribution maps are effective planning tools for evaluating the meteorological conditions for individual farms in those areas where farms are small and interspersed. Public agricultural research centers in each prefecture of Japan have developed mesh meteorological data maps with some kilometers grid cell resolutions for local agriculture, and have been made many studies using mesh meteorological data maps. However, critical variations exist between estimated mesh data and actual meteorological condition within the area of each grid cell. To address this problem, methods of estimating air temperature and solar radiation on a 50 m mesh (latitude 1.5 sec x longitude 2.25 sec) were developed. While many studies with mesh meteorological data maps have been made, numbers of concrete examples of utility for agricultural activity in hilly and mountainous areas have been few. This paper presents therefore some studies for utilization facilitated of mesh meteorological data maps in hilly and mountainous areas. And furthermore, it is proposed some guides to utilize mesh meteorological data maps for the purpose of revitalizing an agricultural activity in hilly and mountainous area with concrete examples

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.

Unstructured mesh adaptivity for urban flooding modelling

Science.gov (United States)

Hu, R.; Fang, F.; Salinas, P.; Pain, C. C.

2018-05-01

Over the past few decades, urban floods have been gaining more attention due to their increase in frequency. To provide reliable flooding predictions in urban areas, various numerical models have been developed to perform high-resolution flood simulations. However, the use of high-resolution meshes across the whole computational domain causes a high computational burden. In this paper, a 2D control-volume and finite-element flood model using adaptive unstructured mesh technology has been developed. This adaptive unstructured mesh technique enables meshes to be adapted optimally in time and space in response to the evolving flow features, thus providing sufficient mesh resolution where and when it is required. It has the advantage of capturing the details of local flows and wetting and drying front while reducing the computational cost. Complex topographic features are represented accurately during the flooding process. For example, the high-resolution meshes around the buildings and steep regions are placed when the flooding water reaches these regions. In this work a flooding event that happened in 2002 in Glasgow, Scotland, United Kingdom has been simulated to demonstrate the capability of the adaptive unstructured mesh flooding model. The simulations have been performed using both fixed and adaptive unstructured meshes, and then results have been compared with those published 2D and 3D results. The presented method shows that the 2D adaptive mesh model provides accurate results while having a low computational cost.

The Role of Vaginal Mesh Procedures in Pelvic Organ Prolapse Surgery in View of Complication Risk

OpenAIRE

Ellington, David R.; Richter, Holly E.

2013-01-01

Synthetic transvaginal mesh has been employed in the treatment of pelvic organ prolapse for more than a decade. As the use of these devices increased during this period so did adverse event reporting. In 2008, the Food and Drug Administration (FDA) Public Health Notification informed physicians and patients of rising concerns with the use of synthetic transvaginal mesh. Shortly thereafter and in parallel to marked increases in adverse event reporting within the Manufacturer and User Device E...

Monitoring and evaluation of wire mesh forming life

Science.gov (United States)

Enemuoh, Emmanuel U.; Zhao, Ping; Kadlec, Alec

2018-03-01

Forming tables are used with stainless steel wire mesh conveyor belts to produce variety of products. The forming tables will typically run continuously for several days, with some hours of scheduled downtime for maintenance, cleaning and part replacement after several weeks of operation. The wire mesh conveyor belts show large variation in their remaining life due to associated variations in their nominal thicknesses. Currently the industry is dependent on seasoned operators to determine the replacement time for the wire mesh formers. The drawback of this approach is inconsistency in judgements made by different operators and lack of data knowledge that can be used to develop decision making system that will be more consistent with wire mesh life prediction and replacement time. In this study, diagnostic measurements about the health of wire mesh former is investigated and developed. The wire mesh quality characteristics considered are thermal measurement, tension property, gage thickness, and wire mesh wear. The results show that real time thermal sensor and wear measurements would provide suitable data for the estimation of wire mesh failure, therefore, can be used as a diagnostic parameter for developing structural health monitoring (SHM) system for stainless steel wire mesh formers.

Feature-Sensitive Tetrahedral Mesh Generation with Guaranteed Quality

OpenAIRE

Wang, Jun; Yu, Zeyun

2012-01-01

Tetrahedral meshes are being extensively used in finite element methods (FEM). This paper proposes an algorithm to generate feature-sensitive and high-quality tetrahedral meshes from an arbitrary surface mesh model. A top-down octree subdivision is conducted on the surface mesh and a set of tetrahedra are constructed using adaptive body-centered cubic (BCC) lattices. Special treatments are given to the tetrahedra near the surface such that the quality of the resulting tetrahedral mesh is prov...

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.

Performance of the hybrid wireless mesh protocol for wireless mesh networks

DEFF Research Database (Denmark)

Boye, Magnus; Staalhagen, Lars

2010-01-01

Wireless mesh networks offer a new way of providing end-user access and deploying network infrastructure. Though mesh networks offer a price competitive solution to wired networks, they also come with a set of new challenges such as optimal path selection, channel utilization, and load balancing....... 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....

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.

Obtuse triangle suppression in anisotropic meshes

KAUST Repository

Sun, Feng; Choi, Yi King; Wang, Wen Ping; Yan, Dongming; Liu, Yang; Lé vy, Bruno L.

2011-01-01

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.

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.

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,...

High-performance metal mesh/graphene hybrid films using prime-location and metal-doped graphene.

Science.gov (United States)

Min, Jung-Hong; Jeong, Woo-Lim; Kwak, Hoe-Min; Lee, Dong-Seon

2017-08-31

We introduce high-performance metal mesh/graphene hybrid transparent conductive layers (TCLs) using prime-location and metal-doped graphene in near-ultraviolet light-emitting diodes (NUV LEDs). Despite the transparency and sheet resistance values being similar for hybrid TCLs, there were huge differences in the NUV LEDs' electrical and optical properties depending on the location of the graphene layer. We achieved better physical stability and current spreading when the graphene layer was located beneath the metal mesh, in direct contact with the p-GaN layer. We further improved the contact properties by adding a very thin Au mesh between the thick Ag mesh and the graphene layer to produce a dual-layered metal mesh. The Au mesh effectively doped the graphene layer to create a p-type electrode. Using Raman spectra, work function variations, and the transfer length method (TLM), we verified the effect of doping the graphene layer after depositing a very thin metal layer on the graphene layers. From our results, we suggest that the nature of the contact is an important criterion for improving the electrical and optical performance of hybrid TCLs, and the method of doping graphene layers provides new opportunities for solving contact issues in other semiconductor devices.

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

Solving implicit multi-mesh flow and conjugate heat transfer problems with RELAP-7

International Nuclear Information System (INIS)

Zou, L.; Peterson, J.; Zhao, H.; Zhang, H.; Andrs, D.; Martineau, R.

2013-01-01

The fully implicit simulation capability of RELAP-7 to solve multi-mesh flow and conjugate heat transfer problems for reactor system safety analysis is presented. Compared to general single-mesh simulations, the reactor system safety analysis-type of code has unique challenges due to its highly simplified, interconnected, one-dimensional, and zero-dimensional flow network describing multiple physics with significantly different time and length scales. To use the Jacobian-free Newton Krylov-type of solver, preconditioning is generally required for the Krylov method. The uniqueness of the reactor safety analysis-type of code in treating the interconnected flow network and conjugate heat transfer also introduces challenges in providing preconditioning matrix. Typical flow and conjugate heat transfer problems involved in reactor safety analysis using RELAP-7, as well as the special treatment on the preconditioning matrix are presented in detail. (authors)

Gradient Calculation Methods on Arbitrary Polyhedral Unstructured Meshes for Cell-Centered CFD Solvers

Science.gov (United States)

Sozer, Emre; Brehm, Christoph; Kiris, Cetin C.

2014-01-01

A survey of gradient reconstruction methods for cell-centered data on unstructured meshes is conducted within the scope of accuracy assessment. Formal order of accuracy, as well as error magnitudes for each of the studied methods, are evaluated on a complex mesh of various cell types through consecutive local scaling of an analytical test function. The tests highlighted several gradient operator choices that can consistently achieve 1st order accuracy regardless of cell type and shape. The tests further offered error comparisons for given cell types, leading to the observation that the "ideal" gradient operator choice is not universal. Practical implications of the results are explored via CFD solutions of a 2D inviscid standing vortex, portraying the discretization error properties. A relatively naive, yet largely unexplored, approach of local curvilinear stencil transformation exhibited surprisingly favorable properties

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.

[CLINICAL EVALUATION OF THE NEW ANTISEPTIC MESHES].

Science.gov (United States)

Gogoladze, M; Kiladze, M; Chkhikvadze, T; Jiqia, D

2016-12-01

Improving the results of hernia treatment and prevention of complications became a goal of our research which included two parts - experimental and clinical. Histomorphological and bacteriological researches showed that the best result out of the 3 control groups was received in case of covering implant "Coladerm"+ with chlorhexidine. Based on the experiment results working process continued in clinics in order to test and introduce new "coladerm"+ chlorhexidine covered poliprophilene meshes into practice. For clinical illustration there were 60 patients introduced to the research who had hernioplasty procedures by different nets: I group - standard meshes+"coladerm"+chlorhexidine, 35 patients; II group - standard meshes +"coladerm", 15 patients; III group - standard meshes, 10 patients. Assessment of the wound and echo-control was done post-surgery on the 8th, 30th and 90th days. This clinical research based on the experimental results once again showed the best anti-microbe features of new antiseptic polymeric biocomposite meshes (standard meshes+"coladerm"+chlorhexidine); timely termination of regeneration and reparation processes without any post-surgery suppurative complications. We hope that new antiseptic polymeric biocomposite meshes presented by us will be successfully used in surgical practice of hernia treatment based on and supported by expermental-clinical research.

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

Characterization of the mechanism of drug-drug interactions from PubMed using MeSH terms.

Science.gov (United States)

Lu, Yin; Figler, Bryan; Huang, Hong; Tu, Yi-Cheng; Wang, Ju; Cheng, Feng

2017-01-01

Identifying drug-drug interaction (DDI) is an important topic for the development of safe pharmaceutical drugs and for the optimization of multidrug regimens for complex diseases such as cancer and HIV. There have been about 150,000 publications on DDIs in PubMed, which is a great resource for DDI studies. In this paper, we introduced an automatic computational method for the systematic analysis of the mechanism of DDIs using MeSH (Medical Subject Headings) terms from PubMed literature. MeSH term is a controlled vocabulary thesaurus developed by the National Library of Medicine for indexing and annotating articles. Our method can effectively identify DDI-relevant MeSH terms such as drugs, proteins and phenomena with high accuracy. The connections among these MeSH terms were investigated by using co-occurrence heatmaps and social network analysis. Our approach can be used to visualize relationships of DDI terms, which has the potential to help users better understand DDIs. As the volume of PubMed records increases, our method for automatic analysis of DDIs from the PubMed database will become more accurate.

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.

Multi-phase Volume Segmentation with Tetrahedral Mesh

DEFF Research Database (Denmark)

Nguyen Trung, Tuan; Dahl, Vedrana Andersen; Bærentzen, Jakob Andreas

Volume segmentation is efficient for reconstructing material structure, which is important for several analyses, e.g. simulation with finite element method, measurement of quantitative information like surface area, surface curvature, volume, etc. We are concerned about the representations of the 3......D volumes, which can be categorized into two groups: fixed voxel grids [1] and unstructured meshes [2]. Among these two representations, the voxel grids are more popular since manipulating a fixed grid is easier than an unstructured mesh, but they are less efficient for quantitative measurements....... In many cases, the voxel grids are converted to explicit meshes, however the conversion may reduce the accuracy of the segmentations, and the effort for meshing is also not trivial. On the other side, methods using unstructured meshes have difficulty in handling topology changes. To reduce the complexity...

Selective separation of oil and water with mesh membranes by capillarity

KAUST Repository

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

2016-01-01

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. © 2016 Elsevier B.V.

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.

MHD simulations on an unstructured mesh

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.

1996-01-01

We describe work on a full MHD code using an unstructured mesh. MH3D++ is an extension of the PPPL MH3D resistive full MHD code. MH3D++ replaces the structured mesh and finite difference / fourier discretization of MH3D with an unstructured mesh and finite element / fourier discretization. Low level routines which perform differential operations, solution of PDEs such as Poisson's equation, and graphics, are encapsulated in C++ objects to isolate the finite element operations from the higher level code. The high level code is the same, whether it is run in structured or unstructured mesh versions. This allows the unstructured mesh version to be benchmarked against the structured mesh version. As a preliminary example, disruptions in DIIID reverse shear equilibria are studied numerically with the MH3D++ code. Numerical equilibria were first produced starting with an EQDSK file containing equilibrium data of a DIII-D L-mode negative central shear discharge. Using these equilibria, the linearized equations are time advanced to get the toroidal mode number n = 1 linear growth rate and eigenmode, which is resistively unstable. The equilibrium and linear mode are used to initialize 3D nonlinear runs. An example shows poloidal slices of 3D pressure surfaces: initially, on the left, and at an intermediate time, on the right

Measured surface magnetic field attenuation of shielded windows and wire mesh over an electrically small enclosure

International Nuclear Information System (INIS)

Hoeft, L.O.; Hofstra, J.S.; Karaskiewicz, R.J.; Wiser, G.

1984-01-01

The surface magnetic field attenuation of five types of shielded transparency (window) material was measured over the frequency range 10 kHz to 100 MHz by installing them on an .61 m x .61 m x .2 m enclosure, placing the enclosure on the wall of a TEM cell and measuring the surface and interior magnetic fields using a computer-controlled network analyzer system. The samples included two thicknesses of conductive grids on acrylic, hardware, cloth with 1/8 and 1/4-inch mesh, and a fine mesh laminated optical display window. These measurements are indicative of an enclosure with aperture coupling; namely, they become frequency-independent at high frequencies. Coarse mesh samples (1/8-1/4-inch mesh) were able to provide 50 to 60 dB of magnetic field reduction at tens of MHz, whereas the finer mesh did slightly better. This behavior is consistent with magnetic polarizability theory. Material thickness did not have an appreciable effect for frequencies above a MHz

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...

Postoperative pain outcomes after transvaginal mesh revision.

Science.gov (United States)

Danford, Jill M; Osborn, David J; Reynolds, W Stuart; Biller, Daniel H; Dmochowski, Roger R

2015-01-01

Although the current literature discusses mesh complications including pain, as well as suggesting different techniques for removing mesh, there is little literature regarding pain outcomes after surgical removal or revision. The purpose of this study is to determine if surgical removal or revision of vaginal mesh improves patient's subjective complaints of pelvic pain associated with original placement of mesh. After obtaining approval from the Vanderbilt University Medical Center Institutional Review Board, a retrospective review of female patients with pain secondary to previous mesh placement who underwent excision or revision of vaginal mesh from January 2000 to August 2012 was performed. Patient age, relevant medical history including menopause status, previous hysterectomy, smoking status, and presence of diabetes, fibromyalgia, interstitial cystitis, and chronic pelvic pain, was obtained. Patients' postoperative pain complaints were assessed. Of the 481 patients who underwent surgery for mesh revision, removal or urethrolysis, 233 patients met our inclusion criteria. One hundred and sixty-nine patients (73 %) reported that their pain improved, 19 (8 %) reported that their pain worsened, and 45 (19 %) reported that their pain remained unchanged after surgery. Prior history of chronic pelvic pain was associated with increased risk of failure of the procedure to relieve pain (OR 0.28, 95 % CI 0.12-0.64, p = 0.003). Excision or revision of vaginal mesh appears to be effective in improving patients' pain symptoms most of the time. Patients with a history of chronic pelvic pain are at an increased risk of no improvement or of worsening pain.

Mesh sensitivity effects on fatigue crack growth by crack-tip blunting and re-sharpening

DEFF Research Database (Denmark)

Tvergaard, Viggo

2007-01-01

remeshing at several stages of the plastic deformation, with studies of the effect of overloads or compressive underloads. Recent published analyses for the first two cycles have shown folding of the crack surface in compression, leading to something that looks like striations. The influence of mesh...... refinement is used to study the possibility of this type of behaviour within the present method. Even with much refined meshes no indication of crack surface folding is found here....

Capacity Analysis of Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

M. I. Gumel

2012-06-01

Full Text Available The next generation wireless networks experienced a great development with emergence of wireless mesh networks (WMNs, which can be regarded as a realistic solution that provides wireless broadband access. The limited available bandwidth makes capacity analysis of the network very essential. While the network offers broadband wireless access to community and enterprise users, the problems that limit the network capacity must be addressed to exploit the optimum network performance. The wireless mesh network capacity analysis shows that the throughput of each mesh node degrades in order of l/n with increasing number of nodes (n in a linear topology. The degradation is found to be higher in a fully mesh network as a result of increase in interference and MAC layer contention in the network.

Field-aligned mesh joinery

OpenAIRE

Cignoni, Paolo; Pietroni, Nico; Malomo, Luigi

2014-01-01

Mesh joinery is an innovative method to produce illustrative shape approximations suitable for fabrication. Mesh joinery is capable of producing complex fabricable structures in an efficient and visually pleasing manner. We represent an input geometry as a set of planar pieces arranged to compose a rigid structure, by exploiting an efficient slit mechanism. Since slices are planar, to fabricate them a standard 2D cutting system is enough. We automatically arrange slices according to a smooth ...

Pure transvaginal excision of mesh erosion involving the bladder.

Science.gov (United States)

Firoozi, Farzeen; Goldman, Howard B

2013-06-01

We present a pure transvaginal approach to the removal of eroded mesh involving the bladder secondary to placement of transvaginal mesh for management of pelvic organ prolapse (POP) using a mesh kit. Although technically challenging, we demonstrate the feasibility of a purely transvaginal approach, avoiding a potentially more morbid transabdominal approach. The video presents the surgical technique of pure transvaginal excision of mesh erosion involving the bladder after mesh placement using a prolapse kit was performed. This video shows that purely transvaginal removal of mesh erosion involving the bladder can be done safely and is feasible.

Experimental Investigation of Discharge Coefficient in Mesh Panel Bottom Intakes

Directory of Open Access Journals (Sweden)

keivan bina

2012-04-01

Full Text Available Bottom racks is a hydraulic structure which is placed in the bed of stream through which, part of flow in the main channel is diverted. These structures have very wide application in industry, irrigation, drainage and etc. Of course much attention had been paid to the study of such structures, but characteristics of flow through bottom racks are complex. The present study was directed to estimate the discharge coefficient of a new kind of bottom racks including both transverse and longitudinal bars that named "mesh panel racks" without considering any solids in the fluid. This kind of bottom intake has advantages from structural point of view and has less deformation under static and dynamic loads. Laboratory setup with three mesh panel intakes was built and the effects of various parameters such as racks slope, porosity and geometry were explored. A dimensional analysis using Buckingham theory showed the effective hydraulic and geometric factors that affect the discharge coefficient (Cd of bottom racks. Then, a statistical approach to determine the discharge coefficient of a rack structure was developed with linear and nonlinear regression using SPSS software. The efficiency of the proposed technique is high enough that the associated error is limited to 10%. Finally, hydraulic performance of mesh panel intakes was compared with regular type of bottom intakes, which consist of longitudinal bars. For this purpose, diverted discharge through both type of intakes calculated in same situation

How to model wireless mesh networks topology

International Nuclear Information System (INIS)

Sanni, M L; Hashim, A A; Anwar, F; Ali, S; Ahmed, G S M

2013-01-01

The specification of network connectivity model or topology is the beginning of design and analysis in Computer Network researches. Wireless Mesh Networks is an autonomic network that is dynamically self-organised, self-configured while the mesh nodes establish automatic connectivity with the adjacent nodes in the relay network of wireless backbone routers. Researches in Wireless Mesh Networks range from node deployment to internetworking issues with sensor, Internet and cellular networks. These researches require modelling of relationships and interactions among nodes including technical characteristics of the links while satisfying the architectural requirements of the physical network. However, the existing topology generators model geographic topologies which constitute different architectures, thus may not be suitable in Wireless Mesh Networks scenarios. The existing methods of topology generation are explored, analysed and parameters for their characterisation are identified. Furthermore, an algorithm for the design of Wireless Mesh Networks topology based on square grid model is proposed in this paper. The performance of the topology generated is also evaluated. This research is particularly important in the generation of a close-to-real topology for ensuring relevance of design to the intended network and validity of results obtained in Wireless Mesh Networks researches

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.

SALOME PLATFORM and TetGen for Polyhedral Mesh Generation

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Yong; Park, Chan Eok; Kim, Shin Whan [KEPCO E and C Company, Inc., Daejeon (Korea, Republic of)

2014-05-15

SPACE and CUPID use the unstructured mesh and they also require reliable mesh generation system. The combination of CAD system and mesh generation system is necessary to cope with a large number of cells and the complex fluid system with structural materials inside. In the past, a CAD system Pro/Engineer and mesh generator Pointwise were evaluated for this application. But, the cost of those commercial CAD and mesh generator is sometimes a great burden. Therefore, efforts have been made to set up a mesh generation system with open source programs. The evaluation of the TetGen has been made in focusing the application for the polyhedral mesh generation. In this paper, SALOME will be evaluated for the efforts in conjunction with TetGen. In section 2, review will be made on the CAD and mesh generation capability of SALOME. SALOME and TetGen codes are being integrated to construct robust polyhedral mesh generator. Edge removal on the flat surface and vertex reattachment to the solid are two challenging tasks. It is worthwhile to point out that the Python script capability of the SALOME should be fully utilized for the future investigation.

Mesh requirements for neutron transport calculations

International Nuclear Information System (INIS)

Askew, J.R.

1967-07-01

Fine-structure calculations are reported for a cylindrical natural uranium-graphite cell using different solution methods (discrete ordinate and collision probability codes) and varying the spatial mesh. It is suggested that of formulations assuming the source constant in a mesh interval the differential approach is generally to be preferred. Due to cancellation between approximations made in the derivation of the finite difference equations and the errors in neglecting source variation, the discrete ordinate code gave a more accurate estimate of fine structure for a given mesh even for unusually coarse representations. (author)

Improved mesh generator for the POISSON Group Codes

International Nuclear Information System (INIS)

Gupta, R.C.

1987-01-01

This paper describes the improved mesh generator of the POISSON Group Codes. These improvements enable one to have full control over the way the mesh is generated and in particular the way the mesh density is distributed throughout this model. A higher mesh density in certain regions coupled with a successively lower mesh density in others keeps the accuracy of the field computation high and the requirements on the computer time and computer memory low. The mesh is generated with the help of codes AUTOMESH and LATTICE; both have gone through a major upgrade. Modifications have also been made in the POISSON part of these codes. We shall present an example of a superconducting dipole magnet to explain how to use this code. The results of field computations are found to be reliable within a few parts in a hundred thousand even in such complex geometries

A third-order moving mesh cell-centered scheme for one-dimensional elastic-plastic flows

Science.gov (United States)

Cheng, Jun-Bo; Huang, Weizhang; Jiang, Song; Tian, Baolin

2017-11-01

A third-order moving mesh cell-centered scheme without the remapping of physical variables is developed for the numerical solution of one-dimensional elastic-plastic flows with the Mie-Grüneisen equation of state, the Wilkins constitutive model, and the von Mises yielding criterion. The scheme combines the Lagrangian method with the MMPDE moving mesh method and adaptively moves the mesh to better resolve shock and other types of waves while preventing the mesh from crossing and tangling. It can be viewed as a direct arbitrarily Lagrangian-Eulerian method but can also be degenerated to a purely Lagrangian scheme. It treats the relative velocity of the fluid with respect to the mesh as constant in time between time steps, which allows high-order approximation of free boundaries. A time dependent scaling is used in the monitor function to avoid possible sudden movement of the mesh points due to the creation or diminishing of shock and rarefaction waves or the steepening of those waves. A two-rarefaction Riemann solver with elastic waves is employed to compute the Godunov values of the density, pressure, velocity, and deviatoric stress at cell interfaces. Numerical results are presented for three examples. The third-order convergence of the scheme and its ability to concentrate mesh points around shock and elastic rarefaction waves are demonstrated. The obtained numerical results are in good agreement with those in literature. The new scheme is also shown to be more accurate in resolving shock and rarefaction waves than an existing third-order cell-centered Lagrangian scheme.

Transvaginal mesh procedures for pelvic organ prolapse.

Science.gov (United States)

Walter, Jens-Erik

2011-02-01

To provide an update on transvaginal mesh procedures, newly available minimally invasive surgical techniques for pelvic floor repair. The discussion is limited to minimally invasive transvaginal mesh procedures. PubMed and Medline were searched for articles published in English, using the key words "pelvic organ prolapse," transvaginal mesh," and "minimally invasive surgery." Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Searches were updated on a regular basis, and articles were incorporated in the guideline to May 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on the Preventive Health Care. Recommendations for practice were ranked according to the method described in that report (Table 1). Counselling for the surgical treatment of pelvic organ prolapse should consider all benefits, harms, and costs of the surgical procedure, with particular emphasis on the use of mesh. 1. Patients should be counselled that transvaginal mesh procedures are considered novel techniques for pelvic floor repair that demonstrate high rates of anatomical cure in uncontrolled short-term case series. (II-2B) 2. Patients should be informed of the range of success rates until stronger evidence of superiority is published. (II-2B) 3. Training specific to transvaginal mesh procedures should be undertaken before procedures are performed. (III-C) 4. Patients should undergo thorough preoperative counselling regarding (a) the potential serious adverse sequelae of transvaginal mesh repairs, including mesh exposure, pain, and dyspareunia; and (b) the limited data available

Predicting mesh density for adaptive modelling of the global atmosphere.

Science.gov (United States)

Weller, Hilary

2009-11-28

The shallow water equations are solved using a mesh of polygons on the sphere, which adapts infrequently to the predicted future solution. Infrequent mesh adaptation reduces the cost of adaptation and load-balancing and will thus allow for more accurate mapping on adaptation. We simulate the growth of a barotropically unstable jet adapting the mesh every 12 h. Using an adaptation criterion based largely on the gradient of the vorticity leads to a mesh with around 20 per cent of the cells of a uniform mesh that gives equivalent results. This is a similar proportion to previous studies of the same test case with mesh adaptation every 1-20 min. The prediction of the mesh density involves solving the shallow water equations on a coarse mesh in advance of the locally refined mesh in order to estimate where features requiring higher resolution will grow, decay or move to. The adaptation criterion consists of two parts: that resolved on the coarse mesh, and that which is not resolved and so is passively advected on the coarse mesh. This combination leads to a balance between resolving features controlled by the large-scale dynamics and maintaining fine-scale features.

A comparison of ANSYS Fluent and STAR-CCM+ simulations for a tangent ogive slender body with a structured mesh at incompressible flow conditions

CSIR Research Space (South Africa)

Schoombie, Janine

2017-10-01

Full Text Available -CCM+ (1) • Why STAR-CCM+? – In 2017 only a STAR-CCM+ v11.06 commercial licence was available – Didn’t want to start from scratch – Test solver with identical mesh STEP 1: • Import Fluent .cas files - Imported as a volume mesh - No mesh continuum... stream_source_info Schoombie_19954_2017.pdf.txt stream_content_type text/plain stream_size 3069 Content-Encoding UTF-8 stream_name Schoombie_19954_2017.pdf.txt Content-Type text/plain; charset=UTF-8 A comparison of ANSYS...

Mesh Adaptation and Shape Optimization on Unstructured Meshes, Phase I

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...

Shape space exploration of constrained meshes

KAUST Repository

Yang, Yongliang; Yang, Yijun; Pottmann, Helmut; Mitra, Niloy J.

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. © 2011 ACM.

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.

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.

Wireless mesh networks.

Science.gov (United States)

Wang, Xinheng

2008-01-01

Wireless telemedicine using GSM and GPRS technologies can only provide low bandwidth connections, which makes it difficult to transmit images and video. Satellite or 3G wireless transmission provides greater bandwidth, but the running costs are high. Wireless networks (WLANs) appear promising, since they can supply high bandwidth at low cost. However, the WLAN technology has limitations, such as coverage. A new wireless networking technology named the wireless mesh network (WMN) overcomes some of the limitations of the WLAN. A WMN combines the characteristics of both a WLAN and ad hoc networks, thus forming an intelligent, large scale and broadband wireless network. These features are attractive for telemedicine and telecare because of the ability to provide data, voice and video communications over a large area. One successful wireless telemedicine project which uses wireless mesh technology is the Emergency Room Link (ER-LINK) in Tucson, Arizona, USA. There are three key characteristics of a WMN: self-organization, including self-management and self-healing; dynamic changes in network topology; and scalability. What we may now see is a shift from mobile communication and satellite systems for wireless telemedicine to the use of wireless networks based on mesh technology, since the latter are very attractive in terms of cost, reliability and speed.

Characterization of the mechanism of drug-drug interactions from PubMed using MeSH terms.

Directory of Open Access Journals (Sweden)

Yin Lu

Full Text Available Identifying drug-drug interaction (DDI is an important topic for the development of safe pharmaceutical drugs and for the optimization of multidrug regimens for complex diseases such as cancer and HIV. There have been about 150,000 publications on DDIs in PubMed, which is a great resource for DDI studies. In this paper, we introduced an automatic computational method for the systematic analysis of the mechanism of DDIs using MeSH (Medical Subject Headings terms from PubMed literature. MeSH term is a controlled vocabulary thesaurus developed by the National Library of Medicine for indexing and annotating articles. Our method can effectively identify DDI-relevant MeSH terms such as drugs, proteins and phenomena with high accuracy. The connections among these MeSH terms were investigated by using co-occurrence heatmaps and social network analysis. Our approach can be used to visualize relationships of DDI terms, which has the potential to help users better understand DDIs. As the volume of PubMed records increases, our method for automatic analysis of DDIs from the PubMed database will become more accurate.

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.

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...

Surgeon Experience and Complications of Transvaginal Prolapse Mesh.

Science.gov (United States)

Kelly, Erin C; Winick-Ng, Jennifer; Welk, Blayne

2016-07-01

To measure the proportion of women with transvaginal prolapse mesh complications and their association with surgeon volume. We conducted a retrospective, population-based cohort study of all women who underwent a mesh-based prolapse procedure using administrative data (hospital procedure and physician billing records) between 2002 and 2013 in Ontario, Canada. The primary outcome was surgical revision of the mesh. Primary exposure was surgeon volume: high (greater than the 75th percentile, requiring a median of five [interquartile range 5-6] procedures per year) and very high (greater than the 90th percentile, requiring a median of 13 [interquartile range 11-14] procedures per year) volume mesh implanters were identified each year. Primary analysis was an adjusted Cox proportional hazards model. A total of 5,488 women underwent mesh implantation by 1 of 368 unique surgeons. Median follow-up time was 5.4 (interquartile range 3.0-8.0) years. We found that 218 women (4.0%) underwent mesh reoperation a median of 1.17 (interquartile range 0.58-2.90) years after implantation. The hazard of reoperation for complications was only lower for patients of very high-volume surgeons (3.0% [145/3,001] compared with 4.8% [73/2,447], adjusted hazards ratio 0.59, 95% confidence interval 0.40-0.86). In multivariable modeling, younger age, concomitant hysterectomy, blood transfusion, and increased medical comorbidity were all associated with vaginal mesh reoperation. Approximately 5% of women who underwent mesh-based prolapse surgery required reoperation for a mesh complication within 10 years. The risk of reoperation was lowest for surgeons performing 14 or more procedures per year.

Indications and Complications Associated with the Removal of 506 Pieces of Vaginal Mesh Used in Pelvic Floor Reconstruction: A Multicenter Study.

Science.gov (United States)

Miklos, John R; Chinthakanan, Orawee; Moore, Robert D; Karp, Deborah R; Nogueiras, Gladys M; Davila, G Willy

2016-10-26

Synthetic mesh utilized to treat stress urinary incontinence (SUI) and pelvic organ prolapse (POP) can often result in postoperative complications. The objectives of this study were to determine: 1) the most common indications for mesh removal; 2) the incidences of the removal of specific mesh procedures (such as suburethral sling [SUS], transvaginal mesh [TVM], or sacrocolpopexy); and 3) the idences and types of surgical complications associated with mesh removal. This was a retrospective study. Design Classification: Canadian Task Force II-3. Three tertiary referral centers in the United States. We examined data from all patients at the three centers who underwent surgical removal of synthetic materials from previous SUS, TVM, and sacrocolpopexy procedures for mesh-related complications from 2011 to 2013. Patients underwent vaginal, intra-abdominal, and inguinal mesh revisions by cutting, partial removal, or total removal of the mesh for mesh-related complications. Overall, 445 patients with complications underwent mesh removal laparoscopically, via groin dissection and/or transvaginally. There were a total of 506 mesh products removed. Of these, 56.5% were slings and 43.5% were for pelvic organ prolapse (POP). Synthetic mesh removed from patients included: transvaginal mesh (TVM) anterior for anterior vaginal prolapse, TVM posterior for posterior vaginal prolapse, sacrocolpopexy mesh, and suburethral slings (SUS) for stress urinary incontinence. Synthetic SUS removed included: retropubic (RPS), transobturator (TOT), and single-incision slings (SIS). TOT was the most common type of sling removed. Patients with a sling who only complained of vaginal pain with or without intercourse underwent a vaginal approach for surgical revision/removal of the sling (86.6%). Patients with an RPS with lower abdominal/suprapubic pain and vaginal pain underwent a vaginal and laparoscopic approach for sling removal (18.4%). Patients with a TOT sling who complained of vaginal and

Energy mesh optimization for multi-level calculation schemes

International Nuclear Information System (INIS)

Mosca, P.; Taofiki, A.; Bellier, P.; Prevost, A.

2011-01-01

The industrial calculations of third generation nuclear reactors are based on sophisticated strategies of homogenization and collapsing at different spatial and energetic levels. An important issue to ensure the quality of these calculation models is the choice of the collapsing energy mesh. In this work, we show a new approach to generate optimized energy meshes starting from the SHEM 281-group library. The optimization model is applied on 1D cylindrical cells and consists of finding an energy mesh which minimizes the errors between two successive collision probability calculations. The former is realized over the fine SHEM mesh with Livolant-Jeanpierre self-shielded cross sections and the latter is performed with collapsed cross sections over the energy mesh being optimized. The optimization is done by the particle swarm algorithm implemented in the code AEMC and multigroup flux solutions are obtained from standard APOLLO2 solvers. By this new approach, a set of new optimized meshes which encompass from 10 to 50 groups has been defined for PWR and BWR calculations. This set will allow users to adapt the energy detail of the solution to the complexity of the calculation (assembly, multi-assembly, two-dimensional whole core). Some preliminary verifications, in which the accuracy of the new meshes is measured compared to a direct 281-group calculation, show that the 30-group optimized mesh offers a good compromise between simulation time and accuracy for a standard 17 x 17 UO 2 assembly with and without control rods. (author)

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.

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

Directory of Open Access Journals (Sweden)

Antonio-Javier Garcia-Sanchez

2016-05-01

Full Text Available 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.

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

Reconfigurable lattice mesh designs for programmable photonic processors.

Science.gov (United States)

Pérez, Daniel; Gasulla, Ivana; Capmany, José; Soref, Richard A

2016-05-30

We propose and analyse two novel mesh design geometries for the implementation of tunable optical cores in programmable photonic processors. These geometries are the hexagonal and the triangular lattice. They are compared here to a previously proposed square mesh topology in terms of a series of figures of merit that account for metrics that are relevant to on-chip integration of the mesh. We find that that the hexagonal mesh is the most suitable option of the three considered for the implementation of the reconfigurable optical core in the programmable processor.

Volume Decomposition and Feature Recognition for Hexahedral Mesh Generation

Energy Technology Data Exchange (ETDEWEB)

GADH,RAJIT; LU,YONG; TAUTGES,TIMOTHY J.

1999-09-27

Considerable progress has been made on automatic hexahedral mesh generation in recent years. Several automatic meshing algorithms have proven to be very reliable on certain classes of geometry. While it is always worth pursuing general algorithms viable on more general geometry, a combination of the well-established algorithms is ready to take on classes of complicated geometry. By partitioning the entire geometry into meshable pieces matched with appropriate meshing algorithm the original geometry becomes meshable and may achieve better mesh quality. Each meshable portion is recognized as a meshing feature. This paper, which is a part of the feature based meshing methodology, presents the work on shape recognition and volume decomposition to automatically decompose a CAD model into meshable volumes. There are four phases in this approach: (1) Feature Determination to extinct decomposition features, (2) Cutting Surfaces Generation to form the ''tailored'' cutting surfaces, (3) Body Decomposition to get the imprinted volumes; and (4) Meshing Algorithm Assignment to match volumes decomposed with appropriate meshing algorithms. The feature determination procedure is based on the CLoop feature recognition algorithm that is extended to be more general. Results are demonstrated over several parts with complicated topology and geometry.

Selective laser vaporization of polypropylene sutures and mesh

Science.gov (United States)

Burks, David; Rosenbury, Sarah B.; Kennelly, Michael J.; Fried, Nathaniel M.

2012-02-01

Complications from polypropylene mesh after surgery for female stress urinary incontinence (SUI) may require tedious surgical revision and removal of mesh materials with risk of damage to healthy adjacent tissue. This study explores selective laser vaporization of polypropylene suture/mesh materials commonly used in SUI. A compact, 7 Watt, 647-nm, red diode laser was operated with a radiant exposure of 81 J/cm2, pulse duration of 100 ms, and 1.0-mm-diameter laser spot. The 647-nm wavelength was selected because its absorption by water, hemoglobin, and other major tissue chromophores is low, while polypropylene absorption is high. Laser vaporization of ~200-μm-diameter polypropylene suture/mesh strands, in contact with fresh urinary tissue samples, ex vivo, was performed. Non-contact temperature mapping of the suture/mesh samples with a thermal camera was also conducted. Photoselective vaporization of polypropylene suture and mesh using a single laser pulse was achieved with peak temperatures of 180 and 232 °C, respectively. In control (safety) studies, direct laser irradiation of tissue alone resulted in only a 1 °C temperature increase. Selective laser vaporization of polypropylene suture/mesh materials is feasible without significant thermal damage to tissue. This technique may be useful for SUI procedures requiring surgical revision.

A Reconfigurable Mesh-Ring Topology for Bluetooth Sensor Networks

Directory of Open Access Journals (Sweden)

Ben-Yi Wang

2018-05-01

Full Text Available In this paper, a Reconfigurable Mesh-Ring (RMR algorithm is proposed for Bluetooth sensor networks. The algorithm is designed in three stages to determine the optimal configuration of the mesh-ring network. Firstly, a designated root advertises and discovers its neighboring nodes. Secondly, a scatternet criterion is built to compute the minimum number of piconets and distributes the connection information for piconet and scatternet. Finally, a peak-search method is designed to determine the optimal mesh-ring configuration for various sizes of networks. To maximize the network capacity, the research problem is formulated by determining the best connectivity of available mesh links. During the formation and maintenance phases, three possible configurations (including piconet, scatternet, and hybrid are examined to determine the optimal placement of mesh links. The peak-search method is a systematic approach, and is implemented by three functional blocks: the topology formation block generates the mesh-ring topology, the routing efficiency block computes the routing performance, and the optimum decision block introduces a decision-making criterion to determine the optimum number of mesh links. Simulation results demonstrate that the optimal mesh-ring configuration can be determined and that the scatternet case achieves better overall performance than the other two configurations. The RMR topology also outperforms the conventional ring-based and cluster-based mesh methods in terms of throughput performance for Bluetooth configurable networks.

Coarse-mesh rebalancing acceleration for eigenvalue problems

International Nuclear Information System (INIS)

Asaoka, T.; Nakahara, Y.; Miyasaka, S.

1974-01-01

The coarse-mesh rebalance method is adopted for Monte Carlo schemes for aiming at accelerating the convergence of a source iteration process. At every completion of the Monte Carlo game for one batch of neutron histories, the scaling factor for the neutron flux is calculated to achieve the neutron balance in each coarse-mesh zone into which the total system is divided. This rebalance factor is multiplied to the weight of each fission source neutron in the coarse-mesh zone for playing the next Monte Carlo game. The numerical examples have shown that the coarse-mesh rebalance Monte Carlo calculation gives a good estimate of the eigenvalue already after several batches with a negligible extra computer time compared to the standard Monte Carlo. 5 references. (U.S.)

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.

Mesh-graft urethroplasty: a case report

OpenAIRE

田中, 敏博; 滝川, 浩; 香川, 征; 長江, 浩朗

1987-01-01

We used a meshed free-foreskin transplant in a two-stage procedure for reconstruction of the extended stricture of urethra after direct vision urethrotomy. The results were excellent. Mesh-graft urethroplasty is a useful method for patients with extended strictures of the urethra or recurrent strictures after several operations.

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)

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.

Selectivity of commercial, larger mesh and square mesh trawl codends for deep water rose shrimp Parapenaeus longirostris (Lucas, 1846 in the Aegean Sea

Directory of Open Access Journals (Sweden)

Hakan Kaykaç

2009-09-01

Full Text Available We investigated the differences between size selectivity of a commercial codend (40 mm diamond mesh – 40D, a larger mesh codend (48 mm diamond mesh – 48D, and a square mesh codend (40 mm square mesh – 40S for Parapenaeus longirostris in international waters of the Aegean Sea. Selectivity data were collected by using a covered codend method and analysed taking between-haul variation into account. The results indicate significant increases in L50 values in relation to an increase in mesh size and when the square mesh is used in the commercial trawl codend. The results demonstrate that the commercially used codend (40D is not selective enough for P. longirostris in terms of length at first maturity. Changing from a 40D to a 48D codend significantly improves selection, with an increase of about 15% in the L50 values (carapace length 14.5 mm for 40D and 16.6 mm for 48D. Similarly, 40 mm square mesh, which has recently been legislated for EU Mediterranean waters, showed a 12.4% higher mean L50 value (16.3 mm than 40 mm diamond mesh for this species. However, despite these improvements, the 48D and 40S codends still need further improvements to obtain higher selectivity closer to the length at first maturity (20 mm carapace length.

High-fidelity meshes from tissue samples for diffusion MRI simulations.

Science.gov (United States)

Panagiotaki, Eleftheria; Hall, Matt G; Zhang, Hui; Siow, Bernard; Lythgoe, Mark F; Alexander, Daniel C

2010-01-01

This paper presents a method for constructing detailed geometric models of tissue microstructure for synthesizing realistic diffusion MRI data. We construct three-dimensional mesh models from confocal microscopy image stacks using the marching cubes algorithm. Random-walk simulations within the resulting meshes provide synthetic diffusion MRI measurements. Experiments optimise simulation parameters and complexity of the meshes to achieve accuracy and reproducibility while minimizing computation time. Finally we assess the quality of the synthesized data from the mesh models by comparison with scanner data as well as synthetic data from simple geometric models and simplified meshes that vary only in two dimensions. The results support the extra complexity of the three-dimensional mesh compared to simpler models although sensitivity to the mesh resolution is quite robust.

Communication Software Performance for Linux Clusters with Mesh Connections

Energy Technology Data Exchange (ETDEWEB)

Jie Chen; William Watson

2003-09-01

Recent progress in copper based commodity Gigabit Ethernet interconnects enables constructing clusters to achieve extremely high I/O bandwidth at low cost with mesh connections. However, the TCP/IP protocol stack cannot match the improved performance of Gigabit Ethernet networks especially in the case of multiple interconnects on a single host. In this paper, we evaluate and compare the performance characteristics of TCP/IP and M-VIA software that is an implementation of VIA.In particular, we focus on the performance of the software systems for a mesh communication architecture and demonstrate the feasibility of using multiple Gigabit Ethernet cards on one host to achieve aggregated bandwidth and latency that are not only better than what TCP provides but also compare favorably to some of the special purpose high-speed networks. In addition, implementation of a new M-VIA driver for one type of Gigabit Ethernet card will be discussed.

[Implants for genital prolapse : Contra mesh surgery].

Science.gov (United States)

Hampel, C

2017-12-01

Alloplastic transvaginal meshes have become very popular in the surgery of pelvic organ prolapse (POP) as did alloplastic suburethral slings in female stress incontinence surgery, but without adequate supporting data. The simplicity of the mesh procedure facilitates its propagation with acceptance of higher revision and complication rates. Since attending physicians do more and more prolapse surgeries without practicing or teaching alternative techniques, expertise in these alternatives, which might be very useful in cases of recurrence, persistence or complications, is permanently lost. It is doubtful that proper and detailed information about alternatives, risks, and benefits of transvaginal alloplastic meshes is provided to every single prolapse patient according to the recommendations of the German POP guidelines, since the number of implanted meshes exceeds the number of properly indicated mesh candidates by far. Although there is no dissent internationally about the available mesh data, thousands of lawsuits in the USA, insolvency of companies due to claims for compensation and unambiguous warnings from foreign urological societies leave German urogynecologists still unimpressed. The existing literature in pelvic organ prolapse exclusively focusses on POP stage and improvement of that stage with surgical therapy. Instead, typical prolapse symptoms should trigger therapy and improvement of these symptoms should be the utmost treatment goal. It is strongly recommended for liability reasons to obtain specific written informed consent.

Ventral hernia repair with poly-4-hydroxybutyrate mesh.

Science.gov (United States)

Plymale, Margaret A; Davenport, Daniel L; Dugan, Adam; Zachem, Amanda; Roth, John Scott

2018-04-01

Biomaterial research has made available a biologically derived fully resorbable poly-4-hydroxybutyrate (P4HB) mesh for use in ventral and incisional hernia repair (VIHR). This study evaluates outcomes of patients undergoing VIHR with P4HB mesh. An IRB-approved prospective pilot study was conducted to assess clinical and quality of life (QOL) outcomes for patients undergoing VIHR with P4HB mesh. Perioperative characteristics were defined. Clinical outcomes, employment status, QOL using 12-item short form survey (SF-12), and pain assessments were followed for 24 months postoperatively. 31 patients underwent VIHR with bioresorbable mesh via a Rives-Stoppa approach with retrorectus mesh placement. The median patient age was 52 years, median body mass index was 33 kg/m 2 , and just over half of the patients were female. Surgical site occurrences occurred in 19% of patients, most of which were seroma. Hernia recurrence rate was 0% (median follow-up = 414 days). Patients had significantly improved QOL at 24 months compared to baseline for SF-12 physical component summary and role emotional (p < 0.05). Ventral hernia repair with P4HB bioresorbable mesh results in favorable outcomes. Early hernia recurrence was not identified among the patient cohort. Quality of life improvements were noted at 24 months versus baseline for this cohort of patients with bioresorbable mesh. Use of P4HB mesh for ventral hernia repair was found to be feasible in this patient population. (ClinicalTrials.gov Identifier: NCT01863030).

Texturing of continuous LOD meshes with the hierarchical texture atlas

Science.gov (United States)

Birkholz, Hermann

2006-02-01

For the rendering of detailed virtual environments, trade-offs have to be made between image quality and rendering time. An immersive experience of virtual reality always demands high frame-rates with the best reachable image qual-ity. Continuous Level of Detail (cLoD) triangle-meshes provide an continuous spectrum of detail for a triangle mesh that can be used to create view-dependent approximations of the environment in real-time. This enables the rendering with a constant number of triangles and thus with constant frame-rates. Normally the construction of such cLoD mesh representations leads to the loss of all texture information of the original mesh. To overcome this problem, a parameter domain can be created, in order to map the surface properties (colour, texture, normal) to it. This parameter domain can be used to map the surface properties back to arbitrary approximations of the original mesh. The parameter domain is often a simplified version of the mesh to be parameterised. This limits the reachable simplification to the domain mesh which has to map the surface of the original mesh with the least possible stretch. In this paper, a hierarchical domain mesh is presented, that scales between very coarse domain meshes and good property-mapping.

Adaptive-mesh zoning by the equipotential method

Energy Technology Data Exchange (ETDEWEB)

Winslow, A.M.

1981-04-01

An adaptive mesh method is proposed for the numerical solution of differential equations which causes the mesh lines to move closer together in regions where higher resolution in some physical quantity T is desired. A coefficient D > 0 is introduced into the equipotential zoning equations, where D depends on the gradient of T . The equations are inverted, leading to nonlinear elliptic equations for the mesh coordinates with source terms which depend on the gradient of D. A functional form of D is proposed.

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...

Current situation of transvaginal mesh repair for pelvic organ prolapse.

Science.gov (United States)

Zhu, Lan; Zhang, Lei

2014-09-01

Surgical mesh is a metallic or polymeric screen intended to be implanted to reinforce soft tissue or bone where weakness exists. Surgical mesh has been used since the 1950s to repair abdominal hernias. In the 1970s, gynecologists began using surgical mesh products to indicate the repair of pelvic organ prolapse (POP), and in the 1990s, gynecologists began using surgical mesh for POP. Then the U.S. Food and Drug Administration (FDA) approved the first surgical mesh product specifically for use in POP. Surgical mesh materials can be divided into several categories. Most surgical mesh devices cleared for POP procedures are composed of non-absorbable synthetic polypropylene. Mesh can be placed in the anterior vaginal wall to aid in the correction of cystocele (anterior repair), in the posterior vaginal wall to aid in correction of rectocele (posterior repair), or attached to the top of the vagina to correct uterine prolapse or vaginal apical prolapse (apical repair). Over the past decades, surgical mesh products for transvaginal POP repair became incorporated into "kits" that included tools to aid in the delivery and insertion of the mesh. Surgical mesh kits continue to evolve, adding new insertion tools, tissue fixation anchors, surgical techniques, and ab- sorbable and biological materials. This procedure has been performed popularly. It was also performed increased in China. But this new technique met some trouble recently and let shake in urogynecology.

Parallel 3D Mortar Element Method for Adaptive Nonconforming Meshes

Science.gov (United States)

Feng, Huiyu; Mavriplis, Catherine; VanderWijngaart, Rob; Biswas, Rupak

2004-01-01

High order methods are frequently used in computational simulation for their high accuracy. An efficient way to avoid unnecessary computation in smooth regions of the solution is to use adaptive meshes which employ fine grids only in areas where they are needed. Nonconforming spectral elements allow the grid to be flexibly adjusted to satisfy the computational accuracy requirements. The method is suitable for computational simulations of unsteady problems with very disparate length scales or unsteady moving features, such as heat transfer, fluid dynamics or flame combustion. In this work, we select the Mark Element Method (MEM) to handle the non-conforming interfaces between elements. A new technique is introduced to efficiently implement MEM in 3-D nonconforming meshes. By introducing an "intermediate mortar", the proposed method decomposes the projection between 3-D elements and mortars into two steps. In each step, projection matrices derived in 2-D are used. The two-step method avoids explicitly forming/deriving large projection matrices for 3-D meshes, and also helps to simplify the implementation. This new technique can be used for both h- and p-type adaptation. This method is applied to an unsteady 3-D moving heat source problem. With our new MEM implementation, mesh adaptation is able to efficiently refine the grid near the heat source and coarsen the grid once the heat source passes. The savings in computational work resulting from the dynamic mesh adaptation is demonstrated by the reduction of the the number of elements used and CPU time spent. MEM and mesh adaptation, respectively, bring irregularity and dynamics to the computer memory access pattern. Hence, they provide a good way to gauge the performance of computer systems when running scientific applications whose memory access patterns are irregular and unpredictable. We select a 3-D moving heat source problem as the Unstructured Adaptive (UA) grid benchmark, a new component of the NAS Parallel

Gear selectivity of large-mesh nets and drumlines used to catch ...

African Journals Online (AJOL)

Catches of sharks and bycatch in large-mesh nets and baited drumlines used by the Queensland Shark Control Program were examined to determine the efficacy of both gear types and assess fishing strategies that minimise their impacts. There were few significant differences in the size of both sharks and bycatch in the ...

Convergence study of global meshing on enamel-cement-bracket finite element model

Science.gov (United States)

Samshuri, S. F.; Daud, R.; Rojan, M. A.; Basaruddin, K. S.; Abdullah, A. B.; Ariffin, A. K.

2017-09-01

This paper presents on meshing convergence analysis of finite element (FE) model to simulate enamel-cement-bracket fracture. Three different materials used in this study involving interface fracture are concerned. Complex behavior ofinterface fracture due to stress concentration is the reason to have a well-constructed meshing strategy. In FE analysis, meshing size is a critical factor that influenced the accuracy and computational time of analysis. The convergence study meshing scheme involving critical area (CA) and non-critical area (NCA) to ensure an optimum meshing sizes are acquired for this FE model. For NCA meshing, the area of interest are at the back of enamel, bracket ligature groove and bracket wing. For CA meshing, area of interest are enamel area close to cement layer, the cement layer and bracket base. The value of constant NCA meshing tested are meshing size 1 and 0.4. The value constant CA meshing tested are 0.4 and 0.1. Manipulative variables are randomly selected and must abide the rule of NCA must be higher than CA. This study employed first principle stresses due to brittle failure nature of the materials used. Best meshing size are selected according to convergence error analysis. Results show that, constant CA are more stable compare to constant NCA meshing. Then, 0.05 constant CA meshing are tested to test the accuracy of smaller meshing. However, unpromising result obtained as the errors are increasing. Thus, constant CA 0.1 with NCA mesh of 0.15 until 0.3 are the most stable meshing as the error in this region are lowest. Convergence test was conducted on three selected coarse, medium and fine meshes at the range of NCA mesh of 0.15 until 3 and CA mesh area stay constant at 0.1. The result shows that, at coarse mesh 0.3, the error are 0.0003% compare to 3% acceptable error. Hence, the global meshing are converge as the meshing size at CA 0.1 and NCA 0.15 for this model.

NeuroTessMesh: A Tool for the Generation and Visualization of Neuron Meshes and Adaptive On-the-Fly Refinement

Directory of Open Access Journals (Sweden)

Juan J. Garcia-Cantero

2017-06-01

Full Text Available Gaining a better understanding of the human brain continues to be one of the greatest challenges for science, largely because of the overwhelming complexity of the brain and the difficulty of analyzing the features and behavior of dense neural networks. Regarding analysis, 3D visualization has proven to be a useful tool for the evaluation of complex systems. However, the large number of neurons in non-trivial circuits, together with their intricate geometry, makes the visualization of a neuronal scenario an extremely challenging computational problem. Previous work in this area dealt with the generation of 3D polygonal meshes that approximated the cells’ overall anatomy but did not attempt to deal with the extremely high storage and computational cost required to manage a complex scene. This paper presents NeuroTessMesh, a tool specifically designed to cope with many of the problems associated with the visualization of neural circuits that are comprised of large numbers of cells. In addition, this method facilitates the recovery and visualization of the 3D geometry of cells included in databases, such as NeuroMorpho, and provides the tools needed to approximate missing information such as the soma’s morphology. This method takes as its only input the available compact, yet incomplete, morphological tracings of the cells as acquired by neuroscientists. It uses a multiresolution approach that combines an initial, coarse mesh generation with subsequent on-the-fly adaptive mesh refinement stages using tessellation shaders. For the coarse mesh generation, a novel approach, based on the Finite Element Method, allows approximation of the 3D shape of the soma from its incomplete description. Subsequently, the adaptive refinement process performed in the graphic card generates meshes that provide good visual quality geometries at a reasonable computational cost, both in terms of memory and rendering time. All the described techniques have been

Resterilized Polypropylene Mesh for Inguinal Hernia Repair

African Journals Online (AJOL)

2018-04-19

Apr 19, 2018 ... Conclusion: The use of sterilized polypropylene mesh for the repair of inguinal ... and nonabsorbable materials to reduce the tissue–mesh. INTRODUCTION ... which we have been practicing in our center since we introduced ...

Clinical study for pancreatic fistula after distal pancreatectomy with mesh reinforcement

Directory of Open Access Journals (Sweden)

Akira Hayashibe

2018-05-01

Full Text Available Summary: Background: The purpose of this cohort study was to determine whether distal pancreatectomy with mesh reinforcement can reduce postoperative pancreatic fistula (POPF rates compared with bare stapler. Methods: In total, 51 patients underwent stapled distal pancreatectomy. Out of these, 22 patients (no mesh group underwent distal pancreatectomy with bare stapler and 29 patients (mesh group underwent distal pancreatectomy with mesh reinforced stapler. The risk factor for clinically relevant POPF (grades B and C after distal pancreatectomy was also evaluated. Results: Clinical characteristics were almost similar in both the groups. The days of the mean hospital stay and drainage tube insertion in the mesh group were significantly fewer than those in the no mesh group. The mean level of amylase in the discharge fluid in the mesh group was also significantly lower than that the in no mesh group. The rate of clinically relevant POPF (grades B and C in the mesh group was significantly lower than that in the no mesh group (p=0.016. Univariate analyses of risk factors for POPF (grades B and C revealed that only mesh reinforcement was associated with POPF (grades B and C. Moreover, on multivariate analyses of POPF risk factors with p value<0.2 in univariate analyses by logistic regression, mesh reinforcement was regarded as a significant factor for POPF(grades B and C. Conclusions: The distal pancreatectomy with mesh reinforced stapler was thought to be favorable for the prevention of clinically relevant POPF (grades B and C. Keywords: mesh reinforcement, pancreatic fistula, pancreatic surgery

Comparing types of local public health agencies in North Carolina.

Science.gov (United States)

Markiewicz, Milissa; Moore, Jill; Foster, Johanna H; Berner, Maureen; Matthews, Gene; Wall, Aimee

2013-01-01

Some states are considering restructuring local public health agencies (LPHAs) in hopes of achieving long-term efficiencies. North Carolina's experience operating different types of LPHAs, such as county health departments, district health departments, public health authorities, and consolidated human services agencies, can provide valuable information to policy makers in other states who are examining how best to organize their local public health system. To identify stakeholders' perceptions of the benefits and challenges associated with different types of LPHAs in North Carolina and to compare LPHA types on selected financial, workforce, and service delivery measures. Focus groups and key informant interviews were conducted to identify stakeholders' perceptions of different LPHA types. To compare LPHA types on finance, workforce, and service delivery measures, descriptive statistical analyses were performed on publicly available quantitative data. North Carolina. Current and former state and local public health practitioners, county commissioners, county managers, assistant managers, state legislators, and others. In addition to identifying stakeholders' perceptions of LPHA types, proportion of total expenditures by funding source, expenditures per capita by funding source, full-time equivalents per 1000 population, and percentage of 127 tracked services offered were calculated. Stakeholders reported benefits and challenges of all LPHA types. LPHA types differ with regard to source of funding, with county health departments and consolidated human services agencies receiving a greater percentage of their funding from county appropriations than districts and authorities, which receive a comparatively larger percentage from other revenues. Types of LPHAs are not entirely distinct from one another, and LPHAs of the same type can vary greatly from one another. However, stakeholders noted differences between LPHA types-particularly with regard to district health

Meshed-Pumpkin Super-Pressure Balloon Design

Science.gov (United States)

Jones, Jack; Yavrouian, Andre

2003-01-01

An improved, lightweight design has been proposed for super-pressure balloons used to carry scientific instruments at high altitudes in the atmosphere of Earth for times as long as 100 days. [A super-pressure balloon is one in which the pressure of the buoyant gas (typically, helium) is kept somewhat above ambient pressure in order to maintain approximately constant density and thereby regulate the altitude.] The proposed design, called "meshed pumpkin," incorporates the basic concept of the pumpkin design, which is so named because of its appearance. The pumpkin design entails less weight than does a spherical design, and the meshed-pumpkin design would reduce weight further. The basic idea of the meshed-pumpkin design is to reinforce the membrane of a pumpkin balloon by attaching a strong, lightweight fabric mesh to its outer surface. The reinforcement would make it possible to reduce the membrane mass to one-third or less of that of the basic pumpkin design while retaining sufficient strength to enable the balloon to remain at approximately constant altitude for months.

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

Anisotropic mesh adaptation for marine ice-sheet modelling

Science.gov (United States)

Gillet-Chaulet, Fabien; Tavard, Laure; Merino, Nacho; Peyaud, Vincent; Brondex, Julien; Durand, Gael; Gagliardini, Olivier

2017-04-01

Improving forecasts of ice-sheets contribution to sea-level rise requires, amongst others, to correctly model the dynamics of the grounding line (GL), i.e. the line where the ice detaches from its underlying bed and goes afloat on the ocean. Many numerical studies, including the intercomparison exercises MISMIP and MISMIP3D, have shown that grid refinement in the GL vicinity is a key component to obtain reliable results. Improving model accuracy while maintaining the computational cost affordable has then been an important target for the development of marine icesheet models. Adaptive mesh refinement (AMR) is a method where the accuracy of the solution is controlled by spatially adapting the mesh size. It has become popular in models using the finite element method as they naturally deal with unstructured meshes, but block-structured AMR has also been successfully applied to model GL dynamics. The main difficulty with AMR is to find efficient and reliable estimators of the numerical error to control the mesh size. Here, we use the estimator proposed by Frey and Alauzet (2015). Based on the interpolation error, it has been found effective in practice to control the numerical error, and has some flexibility, such as its ability to combine metrics for different variables, that makes it attractive. Routines to compute the anisotropic metric defining the mesh size have been implemented in the finite element ice flow model Elmer/Ice (Gagliardini et al., 2013). The mesh adaptation is performed using the freely available library MMG (Dapogny et al., 2014) called from Elmer/Ice. Using a setup based on the inter-comparison exercise MISMIP+ (Asay-Davis et al., 2016), we study the accuracy of the solution when the mesh is adapted using various variables (ice thickness, velocity, basal drag, …). We show that combining these variables allows to reduce the number of mesh nodes by more than one order of magnitude, for the same numerical accuracy, when compared to uniform mesh

New finite volume methods for approximating partial differential equations on arbitrary meshes

International Nuclear Information System (INIS)

Hermeline, F.

2008-12-01

This dissertation presents some new methods of finite volume type for approximating partial differential equations on arbitrary meshes. The main idea lies in solving twice the problem to be dealt with. One addresses the elliptic equations with variable (anisotropic, antisymmetric, discontinuous) coefficients, the parabolic linear or non linear equations (heat equation, radiative diffusion, magnetic diffusion with Hall effect), the wave type equations (Maxwell, acoustics), the elasticity and Stokes'equations. Numerous numerical experiments show the good behaviour of this type of method. (author)

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...

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...

Laparoscopic removal of mesh used in pelvic floor surgery.

Science.gov (United States)

Khong, Su-Yen; Lam, Alan

2009-01-01

Various meshes are being used widely in clinical practice for pelvic reconstructive surgery despite the lack of evidence of their long-term safety and efficacy. Management of complications such as mesh erosion and dyspareunia can be challenging. Most mesh-related complications can probably be managed successfully via the transvaginal route; however, this may be impossible if surgical access is poor. This case report demonstrates the successful laparoscopic removal of mesh after several failed attempts via the vaginal route.

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.

Current role of mesh in vaginal prolapse surgery.

Science.gov (United States)

Richter, Lee A; Carter, Charelle; Gutman, Robert E

2014-10-01

This report summarizes the latest literature on transvaginal mesh (TVM) for the treatment of pelvic organ prolapse, with a focus on indications for use and management of complications. We describe trends in TVM by reviewing the recent literature and summarizing national meeting presentations. Vaginal mesh complications are most often managed surgically, and the majority of patients experiencing mesh-related pain have symptom improvement after intervention. New efforts will focus on identifying variables associated with success after intervention for mesh-related complications, to aid reconstructive pelvic surgeons in outcome prediction and patient counselling. Although the use of TVM has plateaued in recent years, we are seeing an exponential rise in synthetic mesh implant removal. Reconstructive pelvic surgeons advising patients with TVM complications should report that surgical intervention is often necessary, improvement rates of pain-related symptoms after surgery are high, and up to a third may require multiple interventions.

Obturator foramen dissection for excision of symptomatic transobturator mesh.

Science.gov (United States)

Reynolds, W Stuart; Kit, Laura Chang; Kaufman, Melissa R; Karram, Mickey; Bales, Gregory T; Dmochowski, Roger R

2012-05-01

Groin pain after transobturator synthetic mesh placement can be recalcitrant to conservative therapy and ultimately requires surgical excision. We describe our experiences with and technique of obturator foramen dissection for mesh excision. The records of 8 patients treated from 2005 to 2010, were reviewed. Obturator dissection was performed via a lateral groin incision over the inferior pubic ramus at the level of the obturator foramen, typically in conjunction with orthopedic surgery. Five patients had transobturator mid urethral sling surgery for stress urinary incontinence, 2 had mid urethral sling and trocar based anterior vaginal wall mesh kits with transobturator passage of mesh arms for stress urinary incontinence and pelvic organ prolapse, and 1 had an anterior vaginal wall mesh kit for pelvic organ prolapse. Patients had 0 to 2 prior transvaginal mesh excisions before obturator surgery. All patients presented with intractable pain in the area of the obturator foramen and/or medial groin for which conservative treatment measures had failed. Six patients underwent concurrent vaginal and obturator dissection and 2 underwent obturator dissection alone. In all cases residual mesh (3 to 11 cm) was identified and excised from the obturator foramen. Mesh was closely associated to or traversing the adductor longus muscle and tendon with significant fibrous reaction in all cases. Postoperatively 5 patients were cured of pain and/or infection, and 3 reported no or some improvement at a mean followup of 6 months (range 1 to 12). Our experience suggests that surgical excision of residual mesh can alleviate many of the symptoms in many patients. In all cases mesh remnants were identified and removed, and typically involved neuromuscular structures adjacent to the obturator foramen. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Cell-centered particle weighting algorithm for PIC simulations in a non-uniform 2D axisymmetric mesh

Science.gov (United States)

Araki, Samuel J.; Wirz, Richard E.

2014-09-01

Standard area weighting methods for particle-in-cell simulations result in systematic errors on particle densities for a non-uniform mesh in cylindrical coordinates. These errors can be significantly reduced by using weighted cell volumes for density calculations. A detailed description on the corrected volume calculations and cell-centered weighting algorithm in a non-uniform mesh is provided. The simple formulas for the corrected volume can be used for any type of quadrilateral and/or triangular mesh in cylindrical coordinates. Density errors arising from the cell-centered weighting algorithm are computed for radial density profiles of uniform, linearly decreasing, and Bessel function in an adaptive Cartesian mesh and an unstructured mesh. For all the density profiles, it is shown that the weighting algorithm provides a significant improvement for density calculations. However, relatively large density errors may persist at outermost cells for monotonically decreasing density profiles. A further analysis has been performed to investigate the effect of the density errors in potential calculations, and it is shown that the error at the outermost cell does not propagate into the potential solution for the density profiles investigated.

Grid adaptation using chimera composite overlapping meshes

Science.gov (United States)

Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

1994-01-01

The objective of this paper is to perform grid adaptation using composite overlapping meshes in regions of large gradient to accurately capture the salient features during computation. The chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using trilinear interpolation. Application to the Euler equations for shock reflections and to shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well-resolved.

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.

Water Penetration through a Superhydrophobic Mesh During a Drop Impact

Science.gov (United States)

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

2017-01-01

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.

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.

A conceptual framework for technology-enabled and technology-dependent user behavior toward device mesh and mesh app

Directory of Open Access Journals (Sweden)

Ming-Hsiung Hsiao

2018-06-01

Full Text Available The device mesh and mesh app revealed by Gartner as the future strategic technology trend are able to predict people's need from their historic data, then provides the needed services or service innovation to support their activity engagement. However, many theories have identified that it is the motivation, rather than technology, that drives people to engage in activities or tasks. For this reason, this study builds a conceptual framework by integrating the extant logic and theories to explore how future technology would generate benefits for people. It integrates task-technology fit (TTF model and motivation theory (mainly expectancy-value theory to explain such technology user behavior. It also points out the difference between technology-enabled and technology-dependent user behavior and concludes that too much emphasis on the role of technology with too little attention on motivation would distort technology user behavior, and the role of technology as well. Keywords: Device mesh, Mesh app, Expectancy-value theory, Task-technology fit (TTF, Technology-enabled user, Technology-dependent user

Symptom resolution after operative management of complications from transvaginal mesh.

Science.gov (United States)

Crosby, Erin C; Abernethy, Melinda; Berger, Mitchell B; DeLancey, John O; Fenner, Dee E; Morgan, Daniel M

2014-01-01

Complications from transvaginal mesh placed for prolapse often require operative management. The aim of this study is to describe the outcomes of vaginal mesh removal. A retrospective review of all patients having surgery by the urogynecology group in the department of obstetrics and gynecology at our institution for a complication of transvaginal mesh placed for prolapse was performed. Demographics, presenting symptoms, surgical procedures, and postoperative symptoms were abstracted. Comparative statistics were performed using the χ or Fisher's exact test with significance at Pmesh and 84 had follow-up data. The most common presenting signs and symptoms were: mesh exposure, 62% (n=56); pain, 64% (n=58); and dyspareunia, 48% (n=43). During operative management, mesh erosion was encountered unexpectedly in a second area of the vagina in 5% (n=4), in the bladder in 1% (n=1), and in the bowel in 2% (n=2). After vaginal mesh removal, 51% (n=43) had resolution of all presenting symptoms. Mesh exposure was treated successfully in 95% of patients, whereas pain was only successfully treated in 51% of patients. Removal of vaginal mesh is helpful in relieving symptoms of presentation. Patients can be reassured that exposed mesh can almost always be successfully managed surgically, but pain and dyspareunia are only resolved completely in half of patients. III.

Automated quadrilateral mesh generation for digital image structures

Institute of Scientific and Technical Information of China (English)

无

2011-01-01

With the development of advanced imaging technology, digital images are widely used. This paper proposes an automatic quadrilateral mesh generation algorithm for multi-colour imaged structures. It takes an original arbitrary digital image as an input for automatic quadrilateral mesh generation, this includes removing the noise, extracting and smoothing the boundary geometries between different colours, and automatic all-quad mesh generation with the above boundaries as constraints. An application example is...

Bilateral Laparoscopic Totally Extraperitoneal Repair Without Mesh Fixation

OpenAIRE

Dehal, Ahmed; Woodward, Brandon; Johna, Samir; Yamanishi, Frank

2014-01-01

Background and Objectives: Mesh fixation during laparoscopic totally extraperitoneal repair is thought to be necessary to prevent recurrence. However, mesh fixation may increase postoperative chronic pain. This study aimed to describe the experience of a single surgeon at our institution performing this operation. Methods: We performed a retrospective review of the medical records of all patients who underwent bilateral laparoscopic totally extraperitoneal repair without mesh fixation for ing...

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.

Adaptive and dynamic meshing methods for numerical simulations

Science.gov (United States)

Acikgoz, Nazmiye

For the numerical simulation of many problems of engineering interest, it is desirable to have an automated mesh adaption tool capable of producing high quality meshes with an affordably low number of mesh points. This is important especially for problems, which are characterized by anisotropic features of the solution and require mesh clustering in the direction of high gradients. Another significant issue in meshing emerges in the area of unsteady simulations with moving boundaries or interfaces, where the motion of the boundary has to be accommodated by deforming the computational grid. Similarly, there exist problems where current mesh needs to be adapted to get more accurate solutions because either the high gradient regions are initially predicted inaccurately or they change location throughout the simulation. To solve these problems, we propose three novel procedures. For this purpose, in the first part of this work, we present an optimization procedure for three-dimensional anisotropic tetrahedral grids based on metric-driven h-adaptation. The desired anisotropy in the grid is dictated by a metric that defines the size, shape, and orientation of the grid elements throughout the computational domain. Through the use of topological and geometrical operators, the mesh is iteratively adapted until the final mesh minimizes a given objective function. In this work, the objective function measures the distance between the metric of each simplex and a target metric, which can be either user-defined (a-priori) or the result of a-posteriori error analysis. During the adaptation process, one tries to decrease the metric-based objective function until the final mesh is compliant with the target within a given tolerance. However, in regions such as corners and complex face intersections, the compliance condition was found to be very difficult or sometimes impossible to satisfy. In order to address this issue, we propose an optimization process based on an ad

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.

A Rare Complication of Composite Dual Mesh: Migration and Enterocutaneous Fistula Formation

Directory of Open Access Journals (Sweden)

Ozgur Bostanci

2015-01-01

Full Text Available Introduction. Mesh is commonly employed for abdominal hernia repair because it ensures a low recurrence rate. However, enterocutaneous fistula due to mesh migration can occur as a very rare, late complication, for which diagnosis is very difficult. Presentation of Case. Here we report the case of an enterocutaneous fistula due to late mesh migration in a mentally retarded, diabetic, 35-year-old male after umbilical hernia repair with composite dual mesh in 2010. Discussion. Mesh is a foreign substance, because of that some of the complications including hematoma, seroma, foreign body reaction, organ damage, infection, mesh rejection, and fistula formation may occur after implantation of the mesh. In the literature, most cases of mesh-associated enterocutaneous fistula due to migration involved polypropylene meshes. Conclusion. This case serves as a reminder of migration of composite dual meshes.

Grid adaption using Chimera composite overlapping meshes

Science.gov (United States)

Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

1993-01-01

The objective of this paper is to perform grid adaptation using composite over-lapping meshes in regions of large gradient to capture the salient features accurately during computation. The Chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using tri-linear interpolation. Applications to the Euler equations for shock reflections and to a shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well resolved.

Comparison of three different methods for effective introduction of platelet-rich plasma on PLGA woven mesh.

Science.gov (United States)

Lee, Ji-Hye; Nam, Jinwoo; Kim, Hee Joong; Yoo, Jeong Joon

2015-03-11

For successful tissue regeneration, effective cell delivery to defect site is very important. Various types of polymer biomaterials have been developed and applied for effective cell delivery. PLGA (poly lactic-co-glycolic acid), a synthetic polymer, is a commercially available and FDA approved material. Platelet-rich plasma (PRP) is an autologous growth factor cocktail containing various growth factors including PDGF, TGFβ-1 and BMPs, and has shown positive effects on cell behaviors. We hypothesized that PRP pretreatment on PLGA mesh using different methods would cause different patterns of platelet adhesion and stages which would modulate cell adhesion and proliferation on the PLGA mesh. In this study, we pretreated PRP on PLGA using three different methods including simple dripping (SD), dynamic oscillation (DO) and centrifugation (CE), then observed the amount of adhered platelets and their activation stage distribution. The highest amount of platelets was observed on CE mesh and calcium treated CE mesh. Moreover, calcium addition after PRP coating triggered dramatic activation of platelets which showed large and flat morphologies of platelets with rich fibrin networks. Human chondrocytes (hCs) and human bone marrow stromal cells (hBMSCs) were next cultured on PRP-pretreated PLGA meshes using different preparation methods. CE mesh showed a significant increase in the initial cell adhesion of hCs and proliferation of hBMSCs compared with SD and DO meshes. The results demonstrated that the centrifugation method can be considered as a promising coating method to introduce PRP on PLGA polymeric material which could improve cell-material interaction using a simple method.

Comparison of three different methods for effective introduction of platelet-rich plasma on PLGA woven mesh

International Nuclear Information System (INIS)

Lee, Ji-Hye; Nam, Jinwoo; Kim, Hee Joong; Yoo, Jeong Joon

2015-01-01

For successful tissue regeneration, effective cell delivery to defect site is very important. Various types of polymer biomaterials have been developed and applied for effective cell delivery. PLGA (poly lactic-co-glycolic acid), a synthetic polymer, is a commercially available and FDA approved material. Platelet-rich plasma (PRP) is an autologous growth factor cocktail containing various growth factors including PDGF, TGFβ-1 and BMPs, and has shown positive effects on cell behaviors. We hypothesized that PRP pretreatment on PLGA mesh using different methods would cause different patterns of platelet adhesion and stages which would modulate cell adhesion and proliferation on the PLGA mesh. In this study, we pretreated PRP on PLGA using three different methods including simple dripping (SD), dynamic oscillation (DO) and centrifugation (CE), then observed the amount of adhered platelets and their activation stage distribution. The highest amount of platelets was observed on CE mesh and calcium treated CE mesh. Moreover, calcium addition after PRP coating triggered dramatic activation of platelets which showed large and flat morphologies of platelets with rich fibrin networks. Human chondrocytes (hCs) and human bone marrow stromal cells (hBMSCs) were next cultured on PRP-pretreated PLGA meshes using different preparation methods. CE mesh showed a significant increase in the initial cell adhesion of hCs and proliferation of hBMSCs compared with SD and DO meshes. The results demonstrated that the centrifugation method can be considered as a promising coating method to introduce PRP on PLGA polymeric material which could improve cell-material interaction using a simple method. (paper)

Enriching Triangle Mesh Animations with Physically Based Simulation.

Science.gov (United States)

Li, Yijing; Xu, Hongyi; Barbic, Jernej

2017-10-01

We present a system to combine arbitrary triangle mesh animations with physically based Finite Element Method (FEM) simulation, enabling control over the combination both in space and time. The input is a triangle mesh animation obtained using any method, such as keyframed animation, character rigging, 3D scanning, or geometric shape modeling. The input may be non-physical, crude or even incomplete. The user provides weights, specified using a minimal user interface, for how much physically based simulation should be allowed to modify the animation in any region of the model, and in time. Our system then computes a physically-based animation that is constrained to the input animation to the amount prescribed by these weights. This permits smoothly turning physics on and off over space and time, making it possible for the output to strictly follow the input, to evolve purely based on physically based simulation, and anything in between. Achieving such results requires a careful combination of several system components. We propose and analyze these components, including proper automatic creation of simulation meshes (even for non-manifold and self-colliding undeformed triangle meshes), converting triangle mesh animations into animations of the simulation mesh, and resolving collisions and self-collisions while following the input.

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

Interactive Shape Modeling using a Skeleton-Mesh Co-Representation

DEFF Research Database (Denmark)

Bærentzen, Jacob Andreas; Abdrashitov, Rinat; Singh, Karan

2014-01-01

We introduce the Polar-Annular Mesh representation (PAM). A PAM is a mesh-skeleton co-representation designed for the modeling of 3D organic, articulated shapes. A PAM represents a manifold mesh as a partition of polar (triangle fans) and annular (rings of quads) regions. The skeletal topology of...... a PAM to a quad-only mesh. We further present a PAM-based multi-touch sculpting application in order to demonstrate its utility as a shape representation for the interactive modeling of organic, articulated figures as well as for editing and posing of pre-existing models....

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 Pglass 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.

Effect of copaiba oil on correction of abdominal wall defect treated with the use of polypropylene/polyglecaprone mesh

Directory of Open Access Journals (Sweden)

Edson Yuzur Yasojima

2013-02-01

Full Text Available PURPOSE: To evaluate the effects of copaiba oil on the correction of abdominal defect treated with the use of polypropylene/polyglecaprone mesh in rats. METHODS: A defect in the abdominal wall was created and corrected with polypropylene/polyglecaprone mesh in 36 rats. They were randomly distributed into three groups: control, copaiba by oral administration (gavage and copaiba oil dip in the mesh. Euthanasia was performed after seven, 14 and 21 post-operative days. The healing process was analyzed regarding the meshes and macroscopic and microscopic aspects. RESULTS: All animals had abdominal adhesions, which were smaller in the copaiba (gavage group (p<0.05. In microscopy, all animals had an acute inflammation stage and the inflammatory response was best characterized by foreign body-type granulomas around the mesh fragments, which was not found in the mesh fragments within the copaiba dip group. There was a greater area of necrosis and fibrosis in the copaiba dip group compared to the control group (p<0.05. The copaiba (gavage group had a greater quantity of collagen fibers compared to the control group. CONCLUSION: Copaiba oil administered by gavage decreased the amount of abdominal adhesions, besides accelerating the process of collagen fibers formation, without damages within the early stages of healing. However, when used by dip directly on the mesh, it had corrosive effects compromising the healing process of the abdominal wall.

Cartesian anisotropic mesh adaptation for compressible flow

International Nuclear Information System (INIS)

Keats, W.A.; Lien, F.-S.

2004-01-01

Simulating transient compressible flows involving shock waves presents challenges to the CFD practitioner in terms of the mesh quality required to resolve discontinuities and prevent smearing. This paper discusses a novel two-dimensional Cartesian anisotropic mesh adaptation technique implemented for compressible flow. This technique, developed for laminar flow by Ham, Lien and Strong, is efficient because it refines and coarsens cells using criteria that consider the solution in each of the cardinal directions separately. In this paper the method will be applied to compressible flow. The procedure shows promise in its ability to deliver good quality solutions while achieving computational savings. The convection scheme used is the Advective Upstream Splitting Method (Plus), and the refinement/ coarsening criteria are based on work done by Ham et al. Transient shock wave diffraction over a backward step and shock reflection over a forward step are considered as test cases because they demonstrate that the quality of the solution can be maintained as the mesh is refined and coarsened in time. The data structure is explained in relation to the computational mesh, and the object-oriented design and implementation of the code is presented. Refinement and coarsening algorithms are outlined. Computational savings over uniform and isotropic mesh approaches are shown to be significant. (author)

Textile properties of synthetic prolapse mesh in response to uniaxial loading

Science.gov (United States)

Barone, William R.; Moalli, Pamela A.; Abramowitch, Steven D.

2016-01-01

BACKGROUND Although synthetic mesh is associated with superior anatomic outcomes for the repair of pelvic organ prolapse, the benefits of mesh have been questioned because of the relatively high complication rates. To date, the mechanisms that result in such complications are poorly understood, yet the textile characteristics of mesh products are believed to play an important role. Interestingly, the pore diameter of synthetic mesh has been shown to impact the host response after hernia repair greatly, and such findings have served as design criteria for prolapse meshes, with larger pores viewed as more favorable. Although pore size and porosity are well-characterized before implantation, the changes in these textile properties after implantation are unclear; the application of mechanical forces has the potential to greatly alter pore geometries in vivo. Understanding the impact of mechanical loading on the textile properties of mesh is essential for the development of more effective devices for prolapse repair. OBJECTIVE The objective of this study was to determine the effect of tensile loading and pore orientation on mesh porosity and pore dimensions. STUDY DESIGN In this study, the porosity and pore diameter of 4 currently available prolapse meshes were examined in response to uniaxial tensile loads of 0.1, 5, and 10 N while mimicking clinical loading conditions. The textile properties were compared with those observed for the unloaded mesh. Meshes included Gynemesh PS (Ethicon, Somerville, NJ), UltraPro (Artisyn; Ethicon), Restorelle (Coloplast, Minneapolis, MN), and Alyte Y-mesh (Bard, Covington, GA). In addition to the various pore geometries, 3 orientations of Restorelle (0-, 5-, 45-degree offset) and 2 orientations of UltraPro (0-, 90-degree offset) were examined. RESULTS In response to uniaxial loading, both porosity and pore diameter dramatically decreased for most mesh products. The application of 5 N led to reductions in porosity for nearly all groups

Comparison of post-operative wound infection after inguinal hernia repair with polypropylene mesh and polyester mesh

International Nuclear Information System (INIS)

Mughal, M.A.; Ahmed, M.; Sajid, M.T.; Mustafa, Q.U.A.; Shukr, I.; Ahsan, J.

2012-01-01

Objective: To compare post operative wound infection frequency after inguinal hernia repair with polypropylene and polyester mesh using standard Lichtenstein hernioplasty technique. Study Design: Randomized controlled trial. Place and Duration: This study was conducted at general surgery department CMH/MH Rawalpindi from 8th April 2007 to 1st Jan 2008 over a period of 09 months. Patients and Materials: Sixty patients received through outpatient department with diagnosis of inguinal hernia satisfying inclusion/exclusion criteria were included. Patients were divided into two groups randomly. Group 1 included those patients in whom polypropylene mesh was used while group II patients were implanted with polyester mesh. Demographic as well as data concerning post operative wound infection was collected and analyzed. Results: Fifty seven patients (95%) were males while remaining (05%) were females. Mean age in group I was 41.17+-9.99 years while in group II was 41.47+-9.79 years (p=0.907). One patient (3.3%) in each group developed wound infection diagnosed by clinical evidence of pain at wound site, redness, induration and purulent discharge. Conclusion: There is no difference in post operative wound infection rate after inguinal Lichtenstein hernioplasty using either polypropylene or polyester mesh. (author)

Does Attorney Advertising Influence Patient Perceptions of Pelvic Mesh?

Science.gov (United States)

Tippett, Elizabeth; King, Jesse; Lucent, Vincent; Ephraim, Sonya; Murphy, Miles; Taff, Eileen

2018-01-01

To measure the relative influence of attorney advertising on patient perceptions of pelvic mesh compared with a history of surgery and a first urology visit. A 52-item survey was administered to 170 female patients in 2 urology offices between 2014 and 2016. Multiple survey items were combined to form scales for benefit and risk perceptions of pelvic mesh, perceptions of the advertising, attitudes toward pelvic mesh, and knowledge of pelvic mesh and underlying medical conditions. Data were analyzed using hierarchical linear regression models. Exposure to attorney advertising was quite high; 88% reported seeing a mesh-related attorney advertisement in the last 6 months. Over half of patients reported seeing attorney advertisements more than once per week. A history of prior mesh implant surgery was the strongest predictor of benefit and risk perceptions of pelvic mesh. Exposure to attorney advertising was associated with higher risk perceptions but did not significantly affect perceptions of benefits. Past urologist visits increased perceptions of benefits but had no effect on risk perceptions. Attorney advertising appears to have some influence on risk perceptions, but personal experience and discussions with a urogynecologist or urologist also influence patient perceptions. Implications, limitations, and future research are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Mesh Nanoelectronics: Seamless Integration of Electronics with Tissues.

Science.gov (United States)

Dai, Xiaochuan; Hong, Guosong; Gao, Teng; Lieber, Charles M

2018-02-20

Nanobioelectronics represents a rapidly developing field with broad-ranging opportunities in fundamental biological sciences, biotechnology, and medicine. Despite this potential, seamless integration of electronics has been difficult due to fundamental mismatches, including size and mechanical properties, between the elements of the electronic and living biological systems. In this Account, we discuss the concept, development, key demonstrations, and future opportunities of mesh nanoelectronics as a general paradigm for seamless integration of electronics within synthetic tissues and live animals. We first describe the design and realization of hybrid synthetic tissues that are innervated in three dimensions (3D) with mesh nanoelectronics where the mesh serves as both as a tissue scaffold and as a platform of addressable electronic devices for monitoring and manipulating tissue behavior. Specific examples of tissue/nanoelectronic mesh hybrids highlighted include 3D neural tissue, cardiac patches, and vascular constructs, where the nanoelectronic devices have been used to carry out real-time 3D recording of electrophysiological and chemical signals in the tissues. This novel platform was also exploited for time-dependent 3D spatiotemporal mapping of cardiac tissue action potentials during cell culture and tissue maturation as well as in response to injection of pharmacological agents. The extension to simultaneous real-time monitoring and active control of tissue behavior is further discussed for multifunctional mesh nanoelectronics incorporating both recording and stimulation devices, providing the unique capability of bidirectional interfaces to cardiac tissue. In the case of live animals, new challenges must be addressed, including minimally invasive implantation, absence of deleterious chronic tissue response, and long-term capability for monitoring and modulating tissue activity. We discuss each of these topics in the context of implantation of mesh

Moving mesh generation with a sequential approach for solving PDEs

DEFF Research Database (Denmark)

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...... a simple and robust moving mesh algorithm in one or multidimension. In this study, we propose a sequential solution procedure including two separate parts: prediction step to obtain an approximate solution to a next time level (integration of physical PDEs) and regriding step at the next time level (mesh...... generation and solution interpolation). Convection terms, which appear in physical PDEs and a mesh equation, are discretized by a WENO (Weighted Essentially Non-Oscillatory) scheme under the consrvative form. This sequential approach is to keep the advantages of robustness and simplicity for the static...

r-Adaptive mesh generation for shell finite element analysis

International Nuclear Information System (INIS)

Cho, Maenghyo; Jun, Seongki

2004-01-01

An r-adaptive method or moving grid technique relocates a grid so that it becomes concentrated in the desired region. This concentration improves the accuracy and efficiency of finite element solutions. We apply the r-adaptive method to computational mesh of shell surfaces, which is initially regular and uniform. The r-adaptive method, given by Liao and Anderson [Appl. Anal. 44 (1992) 285], aggregate the grid in the region with a relatively high weight function without any grid-tangling. The stress error estimator is calculated in the initial uniform mesh for a weight function. However, since the r-adaptive method is a method that moves the grid, shell surface geometry error such as curvature error and mesh distortion error will increase. Therefore, to represent the exact geometry of a shell surface and to prevent surface geometric errors, we use the Naghdi's shell theory and express the shell surface by a B-spline patch. In addition, using a nine-node element, which is relatively less sensitive to mesh distortion, we try to diminish mesh distortion error in the application of an r-adaptive method. In the numerical examples, it is shown that the values of the error estimator for a cylinder, hemisphere, and torus in the overall domain can be reduced effectively by using the mesh generated by the r-adaptive method. Also, the reductions of the estimated relative errors are demonstrated in the numerical examples. In particular, a new functional is proposed to construct an adjusted mesh configuration by considering a mesh distortion measure as well as the stress error function. The proposed weight function provides a reliable mesh adaptation method after a parameter value in the weight function is properly chosen

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.

Form-finding with polyhedral meshes made simple

KAUST Repository

Tang, Chengcheng; Sun, Xiang; Gomes, Maria Alexandra; Wallner, Johannes; Pottmann, Helmut

2014-01-01

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.

A moving mesh method with variable relaxation time

OpenAIRE

Soheili, Ali Reza; Stockie, John M.

2006-01-01

We propose a moving mesh adaptive approach for solving time-dependent partial differential equations. The motion of spatial grid points is governed by a moving mesh PDE (MMPDE) in which a mesh relaxation time \\tau is employed as a regularization parameter. Previously reported results on MMPDEs have invariably employed a constant value of the parameter \\tau. We extend this standard approach by incorporating a variable relaxation time that is calculated adaptively alongside the solution in orde...

Introducing a distributed unstructured mesh into gyrokinetic particle-in-cell code, XGC

Science.gov (United States)

Yoon, Eisung; Shephard, Mark; Seol, E. Seegyoung; Kalyanaraman, Kaushik

2017-10-01

XGC has shown good scalability for large leadership supercomputers. The current production version uses a copy of the entire unstructured finite element mesh on every MPI rank. Although an obvious scalability issue if the mesh sizes are to be dramatically increased, the current approach is also not optimal with respect to data locality of particles and mesh information. To address these issues we have initiated the development of a distributed mesh PIC method. This approach directly addresses the base scalability issue with respect to mesh size and, through the use of a mesh entity centric view of the particle mesh relationship, provides opportunities to address data locality needs of many core and GPU supported heterogeneous systems. The parallel mesh PIC capabilities are being built on the Parallel Unstructured Mesh Infrastructure (PUMI). The presentation will first overview the form of mesh distribution used and indicate the structures and functions used to support the mesh, the particles and their interaction. Attention will then focus on the node-level optimizations being carried out to ensure performant operation of all PIC operations on the distributed mesh. Partnership for Edge Physics Simulation (EPSI) Grant No. DE-SC0008449 and Center for Extended Magnetohydrodynamic Modeling (CEMM) Grant No. DE-SC0006618.

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...

CAPAClTYANALYSIS OF WIRELESS MESH NET\\VORKS

African Journals Online (AJOL)

The limited available bandwidth makes capacity analysis of the network very essential. ... Wireless mesh networks can also be employed for wide variety ofapplications such ... wireless mesh networks using OPNET (Optimized Network Engineering Tool) Modeller 1-J..5. The .... /bps using I I Mbps data rate and 12000 bits.

HIGH-RESOLUTION SIMULATIONS OF CONVECTION PRECEDING IGNITION IN TYPE Ia SUPERNOVAE USING ADAPTIVE MESH REFINEMENT

International Nuclear Information System (INIS)

Nonaka, A.; Aspden, A. J.; Almgren, A. S.; Bell, J. B.; Zingale, M.; Woosley, S. E.

2012-01-01

We extend our previous three-dimensional, full-star simulations of the final hours of convection preceding ignition in Type Ia supernovae to higher resolution using the adaptive mesh refinement capability of our low Mach number code, MAESTRO. We report the statistics of the ignition of the first flame at an effective 4.34 km resolution and general flow field properties at an effective 2.17 km resolution. We find that off-center ignition is likely, with radius of 50 km most favored and a likely range of 40-75 km. This is consistent with our previous coarser (8.68 km resolution) simulations, implying that we have achieved sufficient resolution in our determination of likely ignition radii. The dynamics of the last few hot spots preceding ignition suggest that a multiple ignition scenario is not likely. With improved resolution, we can more clearly see the general flow pattern in the convective region, characterized by a strong outward plume with a lower speed recirculation. We show that the convective core is turbulent with a Kolmogorov spectrum and has a lower turbulent intensity and larger integral length scale than previously thought (on the order of 16 km s –1 and 200 km, respectively), and we discuss the potential consequences for the first flames.

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.

A Linear-Elasticity Solver for Higher-Order Space-Time Mesh Deformation

Science.gov (United States)

Diosady, Laslo T.; Murman, Scott M.

2018-01-01

A linear-elasticity approach is presented for the generation of meshes appropriate for a higher-order space-time discontinuous finite-element method. The equations of linear-elasticity are discretized using a higher-order, spatially-continuous, finite-element method. Given an initial finite-element mesh, and a specified boundary displacement, we solve for the mesh displacements to obtain a higher-order curvilinear mesh. Alternatively, for moving-domain problems we use the linear-elasticity approach to solve for a temporally discontinuous mesh velocity on each time-slab and recover a continuous mesh deformation by integrating the velocity. The applicability of this methodology is presented for several benchmark test cases.

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...... 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...

Robust diamond meshes with unique wettability properties.

Science.gov (United States)

Yang, Yizhou; Li, Hongdong; Cheng, Shaoheng; Zou, Guangtian; Wang, Chuanxi; Lin, Quan

2014-03-18

Robust diamond meshes with excellent superhydrophobic and superoleophilic properties have been fabricated. Superhydrophobicity is observed for water with varying pH from 1 to 14 with good recyclability. Reversible superhydrophobicity and hydrophilicity can be easily controlled. The diamond meshes show highly efficient water-oil separation and water pH droplet transference.

Transvaginal Excision of an Eroded Sacrocolpopexy Mesh by Using Single-Incision Laparoscopic Surgery Equipment.

Science.gov (United States)

Mohr, Stefan; Siegenthaler, Franziska; Imboden, Sara; Kuhn, Annette; Mueller, Michael D

To show a new technique of using single-incision laparoscopic surgery (SILS) equipment in vaginal surgery to create a "pneumovagina." Explanatory video demonstrating the technique and intraoperative findings. University hospital. The 68-year-old patient was referred with a vaginal mesh erosion that resulted in abscess formation at the vaginal apex. The patient was symptomatic with an increasingly foul-smelling vaginal discharge for about 1 year. She had a laparoscopic sacrocolpopexy in a remote hospital 22 months before the current operation and had a total abdominal hysterectomy 15 years ago. The, patient's history was uneventful without dyspareunia, incontinence or voiding difficulties, and she was otherwise content with the sacrocolpopexy result. The local institutional review board granted exemption for this publication. Frequently, pelvic organ prolapse can only be effectively treated if the surgical procedure comprises support of the central compartment. Laparoscopic sacrocolpopexy shows superior outcomes for this indication, with success rates of up to 96%. However, a rare side effect of laparoscopic sacrocolpopexy is mesh erosion, occurring in up to 2.4% [1]. These erosions are usually treated laparoscopically [2]. In this video we show an alternative route for excision of a symptomatic exposed mesh by using a transvaginal approach: The SILS trocar is used vaginally for abscess irrigation and mesh excision with minimally invasive instruments. For treatment of the abscess and removal of the exposed mesh, the SILS trocar was placed vaginally, and laparoscopic instruments were used. The abscess was incised, cleansed and irrigated, debrided, and the mesh excised. Because no mesh material was exposed after excision, the vagina was not closed to avoid creating a cavity with the risk of promoting reabscess formation, and secondary wound healing was anticipated. Laparoscopy was used to confirm that no intra-abdominal lesion coexisted or occurred. There were

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.

VARIABLE MESH STIFFNESS OF SPUR GEAR TEETH USING ...

African Journals Online (AJOL)

gear engagement. A gear mesh kinematic simulation ... model is appropnate for VMS of a spur gear tooth. The assumptions for ... This process has been continued until one complete tooth meshing cycle is ..... Element Method. Using MATLAB,.

A MATLAB Script for Solving 2D/3D Minimum Compliance Problems using Anisotropic Mesh Adaptation

DEFF Research Database (Denmark)

Jensen, Kristian Ejlebjerg

2017-01-01

We present a pure MATLAB implementation for solving 2D/3D compliance minimization problems using the density method. A filtered design variable with a minimum length is computed using a Helmholtz-type differential equation. The optimality criteria is used as optimizer and to avoid local minima we...... apply continuation of an exponent that controls the stiffness associated with intermediate design variables. We constrain the volume from above and use the implementation to show that optimizations with dynamic meshes can save significant amounts of computational time compared to fixed meshes without...

Crack growth simulation for plural crack using hexahedral mesh generation technique

International Nuclear Information System (INIS)

Orita, Y; Wada, Y; Kikuchi, M

2010-01-01

This paper describes a surface crack growth simulation using a new mesh generation technique. The generated mesh is constituted of all hexahedral elements. Hexahedral elements are suitable for an analysis of fracture mechanics parameters, i.e. stress intensity factor. The advantage of a hexahedral mesh is good accuracy of an analysis and less number of degrees of freedoms than a tetrahedral mesh. In this study, a plural crack growth simulation is computed using the hexahedral mesh and its distribution of stress intensity factor is investigated.

MHD simulations on an unstructured mesh

International Nuclear Information System (INIS)

Strauss, H.R.; Park, W.; Belova, E.; Fu, G.Y.; Sugiyama, L.E.

1998-01-01

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

Towards Blockchain-enabled Wireless Mesh Networks

OpenAIRE

Selimi, Mennan; Kabbinale, Aniruddh Rao; Ali, Anwaar; Navarro, Leandro; Sathiaseelan, Arjuna

2018-01-01

Recently, mesh networking and blockchain are two of the hottest technologies in the telecommunications industry. Combining both can reformulate internet access and make connecting to the Internet not only easy, but affordable too. Hyperledger Fabric (HLF) is a blockchain framework implementation and one of the Hyperledger projects hosted by The Linux Foundation. We evaluate HLF in a real production mesh network and in the laboratory, quantify its performance, bottlenecks and limitations of th...

An Algorithm for Parallel Sn Sweeps on Unstructured Meshes

International Nuclear Information System (INIS)

Pautz, Shawn D.

2002-01-01

A new algorithm for performing parallel S n sweeps on unstructured meshes is developed. The algorithm uses a low-complexity list ordering heuristic to determine a sweep ordering on any partitioned mesh. For typical problems and with 'normal' mesh partitionings, nearly linear speedups on up to 126 processors are observed. This is an important and desirable result, since although analyses of structured meshes indicate that parallel sweeps will not scale with normal partitioning approaches, no severe asymptotic degradation in the parallel efficiency is observed with modest (≤100) levels of parallelism. This result is a fundamental step in the development of efficient parallel S n methods

A novel three-dimensional mesh deformation method based on sphere relaxation

International Nuclear Information System (INIS)

Zhou, Xuan; Li, Shuixiang

2015-01-01

In our previous work (2013) [19], we developed a disk relaxation based mesh deformation method for two-dimensional mesh deformation. In this paper, the idea of the disk relaxation is extended to the sphere relaxation for three-dimensional meshes with large deformations. We develop a node based pre-displacement procedure to apply initial movements on nodes according to their layer indices. Afterwards, the nodes are moved locally by the improved sphere relaxation algorithm to transfer boundary deformations and increase the mesh quality. A three-dimensional mesh smoothing method is also adopted to prevent the occurrence of the negative volume of elements, and further improve the mesh quality. Numerical applications in three-dimension including the wing rotation, bending beam and morphing aircraft are carried out. The results demonstrate that the sphere relaxation based approach generates the deformed mesh with high quality, especially regarding complex boundaries and large deformations

A novel three-dimensional mesh deformation method based on sphere relaxation

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuan [Department of Mechanics & Engineering Science, College of Engineering, Peking University, Beijing, 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing, 100094 (China); Li, Shuixiang, E-mail: lsx@pku.edu.cn [Department of Mechanics & Engineering Science, College of Engineering, Peking University, Beijing, 100871 (China)

2015-10-01

In our previous work (2013) [19], we developed a disk relaxation based mesh deformation method for two-dimensional mesh deformation. In this paper, the idea of the disk relaxation is extended to the sphere relaxation for three-dimensional meshes with large deformations. We develop a node based pre-displacement procedure to apply initial movements on nodes according to their layer indices. Afterwards, the nodes are moved locally by the improved sphere relaxation algorithm to transfer boundary deformations and increase the mesh quality. A three-dimensional mesh smoothing method is also adopted to prevent the occurrence of the negative volume of elements, and further improve the mesh quality. Numerical applications in three-dimension including the wing rotation, bending beam and morphing aircraft are carried out. The results demonstrate that the sphere relaxation based approach generates the deformed mesh with high quality, especially regarding complex boundaries and large deformations.

PERFORMANCE ENHANCEMENT OF A MINIATURE STIRLING CRYOCOOLER WITH A MULTI MESH REGENERATOR DESIGN

Directory of Open Access Journals (Sweden)

KISHOR KUMAR V. V.

2017-06-01

Full Text Available A parametric study has been carried out using the software REGEN 3.3 to optimize the regenerator of a miniature Stirling cryocooler operating with a warm end temperature of 300 K and cold end temperature of 80 K. Regenerator designs which produce the maximum coefficient of performance (COP of the system is considered as an optimized regenerator. The length and diameter of the regenerator were fixed from the cooler system requirements. Single mesh regenerators made of 200, 250, 300, 400 and 450 Stainless Steel wire meshes were considered and the optimum phase angle and mesh size were obtained. A maximum COP of 0.1475 was obtained for 300 mesh regenerator at 70° phase angle. Then multi mesh regenerators were considered with finer mesh on the cold end and coarser mesh on the hot end. The optimum size and length of each mesh in the multi mesh regenerator and the optimum phase angle were calculated. The maximum COP of 0.156 was obtained for 200 300-400 multi mesh regenerator at 70° phase angle. The COP and net refrigeration obtained for an optimized multi mesh regenerator was found to be significantly higher than that of a single mesh regenerator. Thus a multi mesh regenerator design with a proper combination of regenerator mesh size and length can enhance the regenerator effectiveness.

[Current state of transvaginal meshes by resolution of pelvic organ prolapse].

Science.gov (United States)

Jírová, J; Pán, M

Treatment of pelvic organs prolapse with transvaginal mesh kits represents nowadays a widespread surgical method, which partially replaced classic operations due to high success rate and low count of recurrences. Just like any other surgical method, the placement of transvaginal mesh is linked with occurrence of complications. In this article we attempt to review the more and less known facts about trans-vaginal meshes, their efficacy, count of recurrence and the spectrum of complications and we try to compare this technique with traditional surgical methods used to treat pelvic organs prolapse (without graft materials). Review. Department of Obstetrics and Gynecology, Regional hospital Mladá Boleslav a.s., Mladá Boleslav. Overview of the results of recent studies published in the Czech and English language in recent years. Pelvic organ prolapse repair with vaginal mesh has generally lower count of relapse especially in patients with wide genital hiatal area and with major levator ani avulsion. The spectrum of complications differs from classical techniques because of the presence of synthetic nonabsorbable material. Some of the specific complications we did not encounter during classical operations include vaginal mesh erosion, infection of mesh associated with chronic pelvic pain, dyspareunia, protrusion of the mesh into the closest organs or the rejection and progressive extrusion of the mesh. Primary enthusiasm has now been replaced with worries of major complications. Future tasks should therefore be aimed at minimizing the rate of complications associated with transvaginal meshes. Except using well-known and safe materials and providing specialized training of physicians for each mesh implantation technique, other precautions outlined in this article should help, such as a closer specification of indication for the application of transvaginal mesh.

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.

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.

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.

Computational mesh generation for vascular structures with deformable surfaces

International Nuclear Information System (INIS)

Putter, S. de; Laffargue, F.; Breeuwer, M.; Vosse, F.N. van de; Gerritsen, F.A.; Philips Medical Systems, Best

2006-01-01

Computational blood flow and vessel wall mechanics simulations for vascular structures are becoming an important research tool for patient-specific surgical planning and intervention. An important step in the modelling process for patient-specific simulations is the creation of the computational mesh based on the segmented geometry. Most known solutions either require a large amount of manual processing or lead to a substantial difference between the segmented object and the actual computational domain. We have developed a chain of algorithms that lead to a closely related implementation of image segmentation with deformable models and 3D mesh generation. The resulting processing chain is very robust and leads both to an accurate geometrical representation of the vascular structure as well as high quality computational meshes. The chain of algorithms has been tested on a wide variety of shapes. A benchmark comparison of our mesh generation application with five other available meshing applications clearly indicates that the new approach outperforms the existing methods in the majority of cases. (orig.)

Plated nickel wire mesh makes superior catalyst bed

Science.gov (United States)

Sill, M.

1965-01-01

Porous nickel mesh screen catalyst bed produces gas evolution in hydrogen peroxide thrust chambers used for attitude control of space vehicles. The nickel wire mesh disks in the catalyst bed are plated in rugose form with a silver-gold coating.

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...

Fragmentation of Millimeter-Size Hypervelocity Projectiles on Combined Mesh-Plate Bumpers

Directory of Open Access Journals (Sweden)

Aleksandr Cherniaev

2017-01-01

Full Text Available This numerical study evaluates the concept of a combined mesh-plate bumper as a shielding system protecting unmanned spacecraft from small (1 mm orbital debris impacts. Two-component bumpers consisting of an external layer of woven mesh (aluminum or steel directly applied to a surface of the aluminum plate are considered. Results of numerical modeling with a projectile velocity of 7 km/s indicate that, in comparison to the steel mesh-combined bumper, the combination of aluminum mesh and aluminum plate provides better fragmentation of small hypervelocity projectiles. At the same time, none of the combined mesh/plate bumpers provide a significant increase of ballistic properties as compared to an aluminum plate bumper. This indicates that the positive results reported in the literature for bumpers with metallic meshes and large projectiles are not scalable down to millimeter-sized particles. Based on this investigation’s results, a possible modification of the combined mesh/plate bumper is proposed for the future study.

Challenging the Myth: Transvaginal Mesh is Not Associated with Carcinogenesis.

Science.gov (United States)

Chughtai, Bilal; Sedrakyan, Art; Mao, Jialin; Thomas, Dominique; Eilber, Karyn S; Clemens, J Quentin; Anger, Jennifer T

2017-10-01

We sought to determine if there was a potential link between synthetic polypropylene mesh implantation for transvaginal pelvic organ prolapse and stress urinary incontinence, and carcinogenesis using statewide administrative data. Women who underwent transvaginal surgery for pelvic organ prolapse or stress urinary incontinence with mesh between January 2008 and December 2009 in New York State were identified using ICD-9-CM procedure codes and CPT-4 codes. Patients in the mesh cohort were individually matched to 2 control cohorts based on comorbidities and procedure date. Carcinogenesis was determined before and after matching at 1, 2 and 3 years, and during the entire followup time. A total of 2,229 patients who underwent mesh based pelvic organ prolapse surgery and 10,401 who underwent sling surgery for stress urinary incontinence between January 2008 and December 2009 were included in the study. Mean followup was 6 years (range 5 to 7). Exact matching between the mesh and control cohorts resulted in 1,870 pairs for pelvic organ prolapse mesh and cholecystectomy (1:2), 1,278 pairs for pelvic organ prolapse mesh and hysterectomy (1:1), 7,986 pairs for sling and cholecystectomy (1:1) and 3,810 pairs for sling and hysterectomy (1:1). Transvaginal mesh implantation was not associated with an increased risk of a cancer diagnosis (pelvic/local cancers or any cancer) at 1 year and during the entire followup of up to 7 years. Transvaginal surgery with implantation of mesh was not associated with the development of malignancy at a mean followup of 6 years. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Incisional hernia prevention using a cyanoacrilate-fixed retrofascial mesh.

Science.gov (United States)

Hoyuela, Carlos; Juvany, Montserrat; Trias, Miquel; Ardid, Jordi; Martrat, Antoni

2018-01-01

The rate of incisional hernia in high-risk patients (obesity, cancer, etc.) is high, even in laparoscopic surgery. The aim of this study is to evaluate the safety of the use of cyanoacrylate fixed prophylactic meshes in the assistance incision in overweight or obese patients undergoing laparoscopic colorectal surgery. A prospective, non-randomized cohort study of patients undergoing elective laparoscopic resection for colorectal cancer between January 2013 and March 2016 was performed. Those with a body mass index greater than 25kg / m 2 were evaluated to implant a prophylactic meshes fixed with cyanoacrylate (Histoacryl®) as reinforcement of the assistance incision. 52 patients were analyzed (mean body mass index: 28.4±2kg / m 2 ). Prophylactic meshes was implanted in 15 patients. The time to put the mesh in place was always less than 5minutes. There was no significant difference in wound infection rate (12% vs. 10%). No mesh had to be explanted. Although the mean follow-up was shorter (14.1±4 vs. 22.3±9 months), there were no incisional hernia in the mesh group. On the other hand, in the non-mesh group, 1 acute evisceration (2.7%) and 4 incisional hernia of the assistance incision were observed (10.8%). There were no significant differences between groups regarding trocar incisional hernia (6.6 vs. 5.4%). The implantation of a reinforcement prophylactic mesh in overweight or obese patients undergoing laparoscopic colorectal surgery is safe and seems to reduce the short-term rate of incisional hernia. Fixation with cyanoacrylate is a rapid method that facilitates the procedure without additional complications. Copyright © 2017 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

ZONE: a finite element mesh generator

International Nuclear Information System (INIS)

Burger, M.J.

1976-05-01

The ZONE computer program is a finite-element mesh generator which produces the nodes and element description of any two-dimensional geometry. The geometry is subdivided into a mesh of quadrilateral and triangular zones arranged sequentially in an ordered march through the geometry. The order of march can be chosen so that the minimum bandwidth is obtained. The node points are defined in terms of the x and y coordinates in a global rectangular coordinate system. The zones generated are quadrilaterals or triangles defined by four node points in a counterclockwise sequence. Node points defining the outside boundary are generated to describe pressure boundary conditions. The mesh that is generated can be used as input to any two-dimensional as well as any axisymmetrical structure program. The output from ZONE is essentially the input file to NAOS, HONDO, and other axisymmetric finite element programs. 14 figures

Ordering schemes for parallel processing of certain mesh problems

International Nuclear Information System (INIS)

O'Leary, D.

1984-01-01

In this work, some ordering schemes for mesh points are presented which enable algorithms such as the Gauss-Seidel or SOR iteration to be performed efficiently for the nine-point operator finite difference method on computers consisting of a two-dimensional grid of processors. Convergence results are presented for the discretization of u /SUB xx/ + u /SUB yy/ on a uniform mesh over a square, showing that the spectral radius of the iteration for these orderings is no worse than that for the standard row by row ordering of mesh points. Further applications of these mesh point orderings to network problems, more general finite difference operators, and picture processing problems are noted

Interoperable mesh components for large-scale, distributed-memory simulations

International Nuclear Information System (INIS)

Devine, K; Leung, V; Diachin, L; Miller, M

2009-01-01

SciDAC applications have a demonstrated need for advanced software tools to manage the complexities associated with sophisticated geometry, mesh, and field manipulation tasks, particularly as computer architectures move toward the petascale. In this paper, we describe a software component - an abstract data model and programming interface - designed to provide support for parallel unstructured mesh operations. We describe key issues that must be addressed to successfully provide high-performance, distributed-memory unstructured mesh services and highlight some recent research accomplishments in developing new load balancing and MPI-based communication libraries appropriate for leadership class computing. Finally, we give examples of the use of parallel adaptive mesh modification in two SciDAC applications.

H-Morph: An indirect approach to advancing front hex meshing

Energy Technology Data Exchange (ETDEWEB)

OWEN,STEVEN J.; SAIGAL,SUNIL

2000-05-30

H-Morph is a new automatic algorithm for the generation of a hexahedral-dominant finite element mesh for arbitrary volumes. The H-Morph method starts with an initial tetrahedral mesh and systematically transforms and combines tetrahedral into hexahedra. It uses an advancing front technique where the initial front consists of a set of prescribed quadrilateral surface facets. Fronts are individually processed by recovering each of the six quadrilateral faces of a hexahedron from the tetrahedral mesh. Recovery techniques similar to those used in boundary constrained Delaunay mesh generation are used. Tetrahedral internal to the six hexahedral faces are then removed and a hexahedron is formed. At any time during the H-Morph procedure a valid mixed hexahedral-tetrahedral mesh is in existence within the volume. The procedure continues until no tetrahedral remain within the volume, or tetrahedral remain which cannot be transformed or combined into valid hexahedral elements. Any remaining tetrahedral are typically towards the interior of the volume, generally a less critical region for analysis. Transition from tetrahedral to hexahedra in the final mesh is accomplished through pyramid shaped elements. Advantages of the proposed method include its ability to conform to an existing quadrilateral surface mesh, its ability to mesh without the need to decompose or recognize special classes of geometry, and its characteristic well-aligned layers of elements parallel to the boundary. Example test cases are presented on a variety of models.

Development and verification of unstructured adaptive mesh technique with edge compatibility

International Nuclear Information System (INIS)

Ito, Kei; Ohshima, Hiroyuki; Kunugi, Tomoaki

2010-01-01

In the design study of the large-sized sodium-cooled fast reactor (JSFR), one key issue is suppression of gas entrainment (GE) phenomena at a gas-liquid interface. Therefore, the authors have been developed a high-precision CFD algorithm to evaluate the GE phenomena accurately. The CFD algorithm has been developed on unstructured meshes to establish an accurate modeling of JSFR system. For two-phase interfacial flow simulations, a high-precision volume-of-fluid algorithm is employed. It was confirmed that the developed CFD algorithm could reproduce the GE phenomena in a simple GE experiment. Recently, the authors have been developed an important technique for the simulation of the GE phenomena in JSFR. That is an unstructured adaptive mesh technique which can apply fine cells dynamically to the region where the GE occurs in JSFR. In this paper, as a part of the development, a two-dimensional unstructured adaptive mesh technique is discussed. In the two-dimensional adaptive mesh technique, each cell is refined isotropically to reduce distortions of the mesh. In addition, connection cells are formed to eliminate the edge incompatibility between refined and non-refined cells. The two-dimensional unstructured adaptive mesh technique is verified by solving well-known lid-driven cavity flow problem. As a result, the two-dimensional unstructured adaptive mesh technique succeeds in providing a high-precision solution, even though poor-quality distorted initial mesh is employed. In addition, the simulation error on the two-dimensional unstructured adaptive mesh is much less than the error on the structured mesh with a larger number of cells. (author)

An Interpreted Language and System for the Visualization of Unstructured Meshes

Science.gov (United States)

Moran, Patrick J.; Gerald-Yamasaki, Michael (Technical Monitor)

1998-01-01

We present an interpreted language and system supporting the visualization of unstructured meshes and the manipulation of shapes defined in terms of mesh subsets. The language features primitives inspired by geometric modeling, mathematical morphology and algebraic topology. The adaptation of the topology ideas to an interpreted environment, along with support for programming constructs such, as user function definition, provide a flexible system for analyzing a mesh and for calculating with shapes defined in terms of the mesh. We present results demonstrating some of the capabilities of the language, based on an implementation called the Shape Calculator, for tetrahedral meshes in R^3.

Grouper: a compact, streamable triangle mesh data structure.

Science.gov (United States)

Luffel, Mark; Gurung, Topraj; Lindstrom, Peter; Rossignac, Jarek

2014-01-01

We present Grouper: an all-in-one compact file format, random-access data structure, and streamable representation for large triangle meshes. Similarly to the recently published SQuad representation, Grouper represents the geometry and connectivity of a mesh by grouping vertices and triangles into fixed-size records, most of which store two adjacent triangles and a shared vertex. Unlike SQuad, however, Grouper interleaves geometry with connectivity and uses a new connectivity representation to ensure that vertices and triangles can be stored in a coherent order that enables memory-efficient sequential stream processing. We present a linear-time construction algorithm that allows streaming out Grouper meshes using a small memory footprint while preserving the initial ordering of vertices. As a part of this construction, we show how the problem of assigning vertices and triangles to groups reduces to a well-known NP-hard optimization problem, and present a simple yet effective heuristic solution that performs well in practice. Our array-based Grouper representation also doubles as a triangle mesh data structure that allows direct access to vertices and triangles. Storing only about two integer references per triangle--i.e., less than the three vertex references stored with each triangle in a conventional indexed mesh format--Grouper answers both incidence and adjacency queries in amortized constant time. Our compact representation enables data-parallel processing on multicore computers, instant partitioning and fast transmission for distributed processing, as well as efficient out-of-core access. We demonstrate the versatility and performance benefits of Grouper using a suite of example meshes and processing kernels.

Grouper: A Compact, Streamable Triangle Mesh Data Structure

Energy Technology Data Exchange (ETDEWEB)

Luffel, Mark [Georgia Inst. of Technology, Atlanta, GA (United States). Visualization and Usability Center (GVU); Gurung, Topraj [Georgia Inst. of Technology, Atlanta, GA (United States). Visualization and Usability Center (GVU); Lindstrom, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rossignac, Jarek [Georgia Inst. of Technology, Atlanta, GA (United States). Visualization and Usability Center (GVU)

2014-01-01

Here, we present Grouper: an all-in-one compact file format, random-access data structure, and streamable representation for large triangle meshes. Similarly to the recently published SQuad representation, Grouper represents the geometry and connectivity of a mesh by grouping vertices and triangles into fixed-size records, most of which store two adjacent triangles and a shared vertex. Unlike SQuad, however, Grouper interleaves geometry with connectivity and uses a new connectivity representation to ensure that vertices and triangles can be stored in a coherent order that enables memory-efficient sequential stream processing. We also present a linear-time construction algorithm that allows streaming out Grouper meshes using a small memory footprint while preserving the initial ordering of vertices. In this construction, we show how the problem of assigning vertices and triangles to groups reduces to a well-known NP-hard optimization problem, and present a simple yet effective heuristic solution that performs well in practice. Our array-based Grouper representation also doubles as a triangle mesh data structure that allows direct access to vertices and triangles. Storing only about two integer references per triangle-i.e., less than the three vertex references stored with each triangle in a conventional indexed mesh format-Grouper answers both incidence and adjacency queries in amortized constant time. Our compact representation enables data-parallel processing on multicore computers, instant partitioning and fast transmission for distributed processing, as well as efficient out-of-core access. We demonstrate the versatility and performance benefits of Grouper using a suite of example meshes and processing kernels.

Conforming to interface structured adaptive mesh refinement: 3D algorithm and implementation

Science.gov (United States)

Nagarajan, Anand; Soghrati, Soheil

2018-03-01

A new non-iterative mesh generation algorithm named conforming to interface structured adaptive mesh refinement (CISAMR) is introduced for creating 3D finite element models of problems with complex geometries. CISAMR transforms a structured mesh composed of tetrahedral elements into a conforming mesh with low element aspect ratios. The construction of the mesh begins with the structured adaptive mesh refinement of elements in the vicinity of material interfaces. An r-adaptivity algorithm is then employed to relocate selected nodes of nonconforming elements, followed by face-swapping a small fraction of them to eliminate tetrahedrons with high aspect ratios. The final conforming mesh is constructed by sub-tetrahedralizing remaining nonconforming elements, as well as tetrahedrons with hanging nodes. In addition to studying the convergence and analyzing element-wise errors in meshes generated using CISAMR, several example problems are presented to show the ability of this method for modeling 3D problems with intricate morphologies.

The application of TINA in the MESH project

NARCIS (Netherlands)

van Sinderen, Marten J.; Ferreira Pires, Luis; Pires, L.F.; Plagemann, Thomas; Goebel, Vera

1998-01-01

This paper discusses the application of TINA concepts, architectures and related design paradigms in the MESH project. MESH adopted TINA as a means to facilitate the design and implementation of a flexible platform for developing and providing interactive multimedia services. This paper reports on

Cell adhesion on NiTi thin film sputter-deposited meshes

Energy Technology Data Exchange (ETDEWEB)

Loger, K. [Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, University of Kiel (Germany); Engel, A.; Haupt, J. [Department of Cardiovascular Surgery, University Hospital of Schleswig-Holstein, Kiel (Germany); Li, Q. [Biocompatible Nanomaterials, Institute for Materials Science, Faculty of Engineering, University of Kiel (Germany); Lima de Miranda, R. [Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, University of Kiel (Germany); ACQUANDAS GmbH, Kiel (Germany); Quandt, E. [Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, University of Kiel (Germany); Lutter, G. [Department of Cardiovascular Surgery, University Hospital of Schleswig-Holstein, Kiel (Germany); Selhuber-Unkel, C. [Biocompatible Nanomaterials, Institute for Materials Science, Faculty of Engineering, University of Kiel (Germany)

2016-02-01

Scaffolds for tissue engineering enable the possibility to fabricate and form biomedical implants in vitro, which fulfill special functionality in vivo. In this study, free-standing Nickel–Titanium (NiTi) thin film meshes were produced by means of magnetron sputter deposition. Meshes contained precisely defined rhombic holes in the size of 440 to 1309 μm{sup 2} and a strut width ranging from 5.3 to 9.2 μm. The effective mechanical properties of the microstructured superelastic NiTi thin film were examined by tensile testing. These results will be adapted for the design of the holes in the film. The influence of hole and strut dimensions on the adhesion of sheep autologous cells (CD133 +) was studied after 24 h and after seven days of incubation. Optical analysis using fluorescence microscopy and scanning electron microscopy showed that cell adhesion depends on the structural parameters of the mesh. After 7 days in cell culture a large part of the mesh was covered with aligned fibrous material. Cell adhesion is particularly facilitated on meshes with small rhombic holes of 440 μm{sup 2} and a strut width of 5.3 μm. Our results demonstrate that free-standing NiTi thin film meshes have a promising potential for applications in cardiovascular tissue engineering, particularly for the fabrication of heart valves. - Highlights: • Freestanding NiTi thin film scaffolds were fabricated with magnetron sputtering process. • Effective mechanical properties of NiTi scaffolds can be adapted by the mesh structure parameters. • Cell adhesion on the NiTi thin film scaffold is controlled by the structure parameters of the mesh. • Cells strongly adhere after seven days and form a confluent layer on the mesh.

Cell adhesion on NiTi thin film sputter-deposited meshes

International Nuclear Information System (INIS)

Loger, K.; Engel, A.; Haupt, J.; Li, Q.; Lima de Miranda, R.; Quandt, E.; Lutter, G.; Selhuber-Unkel, C.

2016-01-01

Scaffolds for tissue engineering enable the possibility to fabricate and form biomedical implants in vitro, which fulfill special functionality in vivo. In this study, free-standing Nickel–Titanium (NiTi) thin film meshes were produced by means of magnetron sputter deposition. Meshes contained precisely defined rhombic holes in the size of 440 to 1309 μm 2 and a strut width ranging from 5.3 to 9.2 μm. The effective mechanical properties of the microstructured superelastic NiTi thin film were examined by tensile testing. These results will be adapted for the design of the holes in the film. The influence of hole and strut dimensions on the adhesion of sheep autologous cells (CD133 +) was studied after 24 h and after seven days of incubation. Optical analysis using fluorescence microscopy and scanning electron microscopy showed that cell adhesion depends on the structural parameters of the mesh. After 7 days in cell culture a large part of the mesh was covered with aligned fibrous material. Cell adhesion is particularly facilitated on meshes with small rhombic holes of 440 μm 2 and a strut width of 5.3 μm. Our results demonstrate that free-standing NiTi thin film meshes have a promising potential for applications in cardiovascular tissue engineering, particularly for the fabrication of heart valves. - Highlights: • Freestanding NiTi thin film scaffolds were fabricated with magnetron sputtering process. • Effective mechanical properties of NiTi scaffolds can be adapted by the mesh structure parameters. • Cell adhesion on the NiTi thin film scaffold is controlled by the structure parameters of the mesh. • Cells strongly adhere after seven days and form a confluent layer on the mesh.

Mesh Network Architecture for Enabling Inter-Spacecraft Communication

Science.gov (United States)

Becker, Christopher; Merrill, Garrick

2017-01-01

To enable communication between spacecraft operating in a formation or small constellation, a mesh network architecture was developed and tested using a time division multiple access (TDMA) communication scheme. The network is designed to allow for the exchange of telemetry and other data between spacecraft to enable collaboration between small spacecraft. The system uses a peer-to-peer topology with no central router, so that it does not have a single point of failure. The mesh network is dynamically configurable to allow for addition and subtraction of new spacecraft into the communication network. Flight testing was performed using an unmanned aerial system (UAS) formation acting as a spacecraft analogue and providing a stressing environment to prove mesh network performance. The mesh network was primarily devised to provide low latency, high frequency communication but is flexible and can also be configured to provide higher bandwidth for applications desiring high data throughput. The network includes a relay functionality that extends the maximum range between spacecraft in the network by relaying data from node to node. The mesh network control is implemented completely in software making it hardware agnostic, thereby allowing it to function with a wide variety of existing radios and computing platforms..

Adaptive Mesh Iteration Method for Trajectory Optimization Based on Hermite-Pseudospectral Direct Transcription

Directory of Open Access Journals (Sweden)

Humin Lei

2017-01-01

Full Text Available An adaptive mesh iteration method based on Hermite-Pseudospectral is described for trajectory optimization. The method uses the Legendre-Gauss-Lobatto points as interpolation points; then the state equations are approximated by Hermite interpolating polynomials. The method allows for changes in both number of mesh points and the number of mesh intervals and produces significantly smaller mesh sizes with a higher accuracy tolerance solution. The derived relative error estimate is then used to trade the number of mesh points with the number of mesh intervals. The adaptive mesh iteration method is applied successfully to the examples of trajectory optimization of Maneuverable Reentry Research Vehicle, and the simulation experiment results show that the adaptive mesh iteration method has many advantages.

Vacuum assisted closure therapy in the treatment of mesh infection after hernia repair.

Science.gov (United States)

Tamhankar, A P; Ravi, K; Everitt, N J

2009-10-01

Mesh related infection after prosthetic abdominal wall hernia repair is a difficult clinical problem, particularly in an era of evolving microbial resistance. Commonly advocated treatment for such infection involves complete mesh excision which usually leaves a complicated weak wound. We report the use ofVAC therapy for mesh infections that allows mesh preservation leaving a sound wound. From june 2002 to January 2007, four patients with mesh related infection after abdominal wall hernia repair were treated with VAC therapy. Patients' notes were reviewed to gather clinical details. Mesh infection was evident after a variable period (day three to eight years) following hernia repair. Of the four patients, one had infection with methicillin resistant Staphylococcus aureus (MRSA), while the bacteriological cultures from two confirmed Staphylococcus aureus in one and a mixture of Pseudomonas and enterococcus species in the other. One patient failed to show significant bacterial growth on pus swab culture, having had prior broad-spectrum antibiotic treatment for mesh infection. Three patients had complete mesh preservation and one had partial mesh excision. All patients were treated with VAC therapy, following the drainage of their operation sites, until the visible mesh was covered with granulation (one to seven weeks). No patient had a recurrent hernia after complete wound healing. VAC therapy allows salvage of infected exposed mesh by promoting granulation through the mesh. Judicious use of VAC therapy may prevent the need of mesh excision and its wound related complications.

Coarse-mesh method for multidimensional, mixed-lattice diffusion calculations

International Nuclear Information System (INIS)

Dodds, H.L. Jr.; Honeck, H.C.; Hostetler, D.E.

1977-01-01

A coarse-mesh finite difference method has been developed for multidimensional, mixed-lattice reactor diffusion calculations, both statics and kinetics, in hexagonal geometry. Results obtained with the coarse-mesh (CM) method have been compared with a conventional mesh-centered finite difference method and with experiment. The results of this comparison indicate that the accuracy of the CM method for highly heterogeneous (mixed) lattices using one point per hexagonal mesh element (''hex'') is about the same as the conventional method with six points per hex. Furthermore, the computing costs (i.e., central processor unit time and core storage requirements) of the CM method with one point per hex are about the same as the conventional method with one point per hex

Use of polypropylene mesh in hernioplasty by Lichtenstein's technique

International Nuclear Information System (INIS)

Montejo Sainz, Jesus Enrique; Pisonero Socias, Juan Jose

2011-01-01

INTRODUCTION. The aim of present study was to assess the benefit using the prosthesis (polypropylene mesh) in the hernioplasty using the Lichtenstein's technique in the 'Joaquin Albarran' Clinical Surgical Hospital. METHODS. A prospective study (with an interval of 14 months) was conducted in 140 surgical interventions carried out using the Lichtenstein's technique in patients presenting with inguinal hernia. One hundred and ten patients were excluded due to interventions were of ambulatory method. The following data were studied: type of hernia found in the physical examination, age, sex, and race, type of job, intervention's date, and technique used as well as the complications during the immediate postoperative time. Also, the hernia's relapse after operation, surgical complications and tolerance to polypropylene mesh were taking into account. RESULTS. There was predominance of male sex confirming a direct influence among types of jobs requiring a strong physical effort and the appearance of inguinal hernias (63,3 %). There were only three complications: a hematoma and two seromas. There were not relapses and any case of infection, both local and systemic. The use of prophylactic antibiotics showed an appropriate cost-benefit relationship. CONCLUSIONS. The old age, the male sex and a sustained physical effort have a directly proportional relation to appearance of inguinal hernias. The feasibility of Lichtenstein's hernioplasty, the null incidence of hernia relapses and no appearance of complications including the rejection to prosthetic material, favoured the use of polypropylene in this plasty. Authors recommended the use of perioperative prophylactic antibiotic therapy to avoid wound's infection and thus to secure the result of surgical intervention and its durability. (author)

Unstructured Mesh Movement and Viscous Mesh Generation for CFD-Based Design Optimization, Phase II

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)...

Status of the Polyhedral Mesh Generator using SALOME PLATFORM and TetGen

International Nuclear Information System (INIS)

Lee, Sang Yong; Park, Chan Eok; Kim, Shin Whan

2014-01-01

Recently developed porous body approach codes such as SPACE and CUPID require a CAD system to estimate the porosity. Since they use the unstructured mesh and they also require reliable mesh generation system. The combination of CAD system and mesh generation system is necessary to cope with a large number of cells and the complex fluid system with structural materials inside. In the past, a CAD system Pro/Engineer and mesh generator Pointwise were evaluated for this application. But, the cost of those commercial CAD and mesh generator is sometimes a great burden. Therefore, efforts have been made to set up a mesh generation system with open source programs. The evaluation of the TetGen has been made in focusing the application for the polyhedral mesh generation. In this paper, SALOME will be described for the efforts to combine TetGen with it. In section 2, brief introduction will be made on the CAD and mesh generation capability of SALOME and Tetgen. SALOME and TetGen codes are being integrated to construct robust polyhedral mesh generator. Procedures to merge boundary faces and to cut concave cells are developed to remove concave cells to get final convex polyhedral mesh. Treating the internal boundary face, i.e. non-manifold face will be the next task in the future investigation

Parallel Performance Optimizations on Unstructured Mesh-based Simulations

Energy Technology Data Exchange (ETDEWEB)

Sarje, Abhinav; Song, Sukhyun; Jacobsen, Douglas; Huck, Kevin; Hollingsworth, Jeffrey; Malony, Allen; Williams, Samuel; Oliker, Leonid

2015-01-01

© The Authors. Published by Elsevier B.V. This paper addresses two key parallelization challenges the unstructured mesh-based ocean modeling code, MPAS-Ocean, which uses a mesh based on Voronoi tessellations: (1) load imbalance across processes, and (2) unstructured data access patterns, that inhibit intra- and inter-node performance. Our work analyzes the load imbalance due to naive partitioning of the mesh, and develops methods to generate mesh partitioning with better load balance and reduced communication. Furthermore, we present methods that minimize both inter- and intranode data movement and maximize data reuse. Our techniques include predictive ordering of data elements for higher cache efficiency, as well as communication reduction approaches. We present detailed performance data when running on thousands of cores using the Cray XC30 supercomputer and show that our optimization strategies can exceed the original performance by over 2×. Additionally, many of these solutions can be broadly applied to a wide variety of unstructured grid-based computations.

Sacral colpopexy versus transvaginal mesh colpopexy in obese patients.

Science.gov (United States)

McDermott, Colleen D; Park, Jean; Terry, Colin L; Woodman, Patrick J; Hale, Douglass S

2013-05-01

Obesity can predispose women to pelvic organ prolapse and can also affect the success of pelvic organ prolapse surgery. The purpose of this study was to compare the postoperative anatomical outcomes following sacral colpopexy (SC) and transvaginal mesh colpopexy in a group of obese women with pelvic organ prolapse. We conducted a retrospective cohort study of obese women who underwent SC (n = 56) or transvaginal mesh colpopexy (n = 35). Follow-up ranged from 6 to 12 months. Preoperative, perioperative, and postoperative variables were compared using Student t, Mann-Whitney U, and Fisher exact tests, and by analysis of covariance. The women in the SC group had significantly higher mean apical vaginal measurements (P transvaginal mesh colpopexy group. There were no significant differences between the groups for other postoperative outcomes, including mesh erosion, recurrent prolapse symptoms, dyspareunia, and surgical satisfaction (P > 0.05). In these 91 obese patients with pelvic organ prolapse, SC resulted in better anatomical outcomes than transvaginal mesh colpopexy. However, the two procedures had similar outcomes with regard to recurrent symptoms and surgical satisfaction.

DOT-IV two-dimensional discrete ordinates transport code with space-dependent mesh and quadrature

International Nuclear Information System (INIS)

Rhoades, W.A.; Simpson, D.B.; Childs, R.L.; Engle, W.W. Jr.

1979-01-01

DOT IV is designed to allow very large problems to be solved on a wide range of computers and memory arrangements. New flexibility in both space-mesh and directional-quadrature specification is allowed. For example, the radial mesh in an R-Z problem can vary with axial position. The directional quadrature can vary with both space and energy group. Several features improve performance on both deep penetration and criticality problems. The program has been checked and used extensively on several types of computers. All of the features have been insured operable except the following two, which must not be used: criticality searches and P/sub L/ variable by group or material. Diffusion theory problems must not use internal or external boundary sources, variable mesh, or variable quadrature. A diffusion iteration cannot produce internal boundary source output or ''angular flux tape.'' The P 1 module is very limited. The special geometries, INGEOM greater than or equal to 10, have not been completely checked and are not guaranteed. 7 figures, 1 table

Most Common Publication Types in Radiology Journals:: What is the Level of Evidence?

Science.gov (United States)

Rosenkrantz, Andrew B; Pinnamaneni, Niveditha; Babb, James S; Doshi, Ankur M

2016-05-01

This study aimed to assess the most common publication types in radiology journals, as well as temporal trends and association with citation frequency. PubMed was searched to extract all published articles having the following "Publication Type" indices: "validation studies," "meta-analysis," "clinical trial," "comparative study," "evaluation study," "guideline," "multicenter study," "randomized study," "review," "editorial," "case report," and "technical report." The percentage of articles within each category published within clinical radiology journals was computed. Normalized percentages for each category were also computed on an annual basis. Citation counts within a 2-year window following publication were obtained using Web of Science. Overall trends were assessed. Publication types with the highest fraction in radiology journals were technical reports, evaluation studies, and case reports (4.8% to 5.8%). Publication types with the lowest fraction in radiology journals were randomized trials, multicenter studies, and meta-analyses (0.8% to 1.5%). Case reports showed a significant decrease since 1999, with accelerating decline since 2007 (P = 0.002). Publication types with highest citation counts were meta-analyses, guidelines, and multicenter studies (8.1 ± 10.7 to 12.9 ± 5.1). Publication types with lowest citation counts were case reports, editorials, and technical reports (1.4 ± 2.4 to 2.9 ± 4.3). The representation in radiology journals and citation frequency of the publication types showed weak inverse correlation (r = -0.372). Radiology journals have historically had relatively greater representation of less frequently cited publication types. Various strategies, including methodological training, multidisciplinary collaboration, national support networks, as well as encouragement of higher level of evidence by funding agencies and radiology journals themselves, are warranted to improve the impact of radiological research

Heterogeneous Wireless Mesh Network Technology Evaluation for Space Proximity and Surface Applications

Science.gov (United States)

DeCristofaro, Michael A.; Lansdowne, Chatwin A.; Schlesinger, Adam M.

2014-01-01

NASA has identified standardized wireless mesh networking as a key technology for future human and robotic space exploration. Wireless mesh networks enable rapid deployment, provide coverage in undeveloped regions. Mesh networks are also self-healing, resilient, and extensible, qualities not found in traditional infrastructure-based networks. Mesh networks can offer lower size, weight, and power (SWaP) than overlapped infrastructure-perapplication. To better understand the maturity, characteristics and capability of the technology, we developed an 802.11 mesh network consisting of a combination of heterogeneous commercial off-the-shelf devices and opensource firmware and software packages. Various streaming applications were operated over the mesh network, including voice and video, and performance measurements were made under different operating scenarios. During the testing several issues with the currently implemented mesh network technology were identified and outlined for future work.

An optimization-based framework for anisotropic simplex mesh adaptation

Science.gov (United States)

Yano, Masayuki; Darmofal, David L.

2012-09-01

We present a general framework for anisotropic h-adaptation of simplex meshes. Given a discretization and any element-wise, localizable error estimate, our adaptive method iterates toward a mesh that minimizes error for a given degrees of freedom. Utilizing mesh-metric duality, we consider a continuous optimization problem of the Riemannian metric tensor field that provides an anisotropic description of element sizes. First, our method performs a series of local solves to survey the behavior of the local error function. This information is then synthesized using an affine-invariant tensor manipulation framework to reconstruct an approximate gradient of the error function with respect to the metric tensor field. Finally, we perform gradient descent in the metric space to drive the mesh toward optimality. The method is first demonstrated to produce optimal anisotropic meshes minimizing the L2 projection error for a pair of canonical problems containing a singularity and a singular perturbation. The effectiveness of the framework is then demonstrated in the context of output-based adaptation for the advection-diffusion equation using a high-order discontinuous Galerkin discretization and the dual-weighted residual (DWR) error estimate. The method presented provides a unified framework for optimizing both the element size and anisotropy distribution using an a posteriori error estimate and enables efficient adaptation of anisotropic simplex meshes for high-order discretizations.

Design Investigation on Applicable Mesh Structures for Medical Stent Applications

Science.gov (United States)

Asano, Shoji; He, Jianmei

2017-11-01

In recent years, utilization of medical stents is one of effective treatments for stenosis and occlusion occurring in a living body’s lumen indispensable for maintenance of human life such as superficial femoral artery (SFA) occlusion. However, there are concerns about the occurrence of fatigue fractures caused by stress concentrations, neointimal hyperplasia and the like due to the shape structure and the manufacturing method in the conventional stents, and a stent having high strength and high flexibility is required. Therefore, in this research, applicable mesh structures for medical stents based on the design concepts of high strength, high flexibility are interested to solve various problem of conventional stent. According to the shape and dimensions of SFA occlusion therapy stent and indwelling delivery catheter, shape design of the meshed stent are performed using 3-dimensional CAD software Solid Works first. Then analytical examination on storage characteristics and compression characteristics of such mesh structure applied stent models were carried out through finite element analysis software ANSYS Workbench. Meshed stent models with higher strength and higher flexibility with integral molding are investigated analytically. It was found that the storage characteristics and compression characteristics of meshed stent modles are highly dependent on the basic mesh shapes with same surface void ratio. Trade-off relationship between flexibility and storage characteristics is found exited, it is required to provide appropriate curvatures during basic mesh shape design.

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.

Open preperitoneal groin hernia repair with mesh

DEFF Research Database (Denmark)

Andresen, Kristoffer; Rosenberg, Jacob

2017-01-01

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...... 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......-analysis. Open preperitoneal techniques with placement of a mesh through an open approach seem promising compared with the standard anterior techniques. This systematic review provides an overview of these techniques together with a description of surgical methods and clinical outcomes....

Open preperitoneal groin hernia repair with mesh

DEFF Research Database (Denmark)

Andresen, Kristoffer; Rosenberg, Jacob

2017-01-01

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......: 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......-analysis. Open preperitoneal techniques with placement of a mesh through an open approach seem promising compared with the standard anterior techniques. This systematic review provides an overview of these techniques together with a description of surgical methods and clinical outcomes....

Robotic removal of eroded vaginal mesh into the bladder.

Science.gov (United States)

Macedo, Francisco Igor B; O'Connor, Jeffrey; Mittal, Vijay K; Hurley, Patrick

2013-11-01

Vaginal mesh erosion into the bladder after midurethral sling procedure or cystocele repair is uncommon, with only a few cases having been reported in the literature. The ideal surgical management is still controversial. Current options for removal of eroded mesh include: endoscopic, transvaginal or abdominal (either open or laparoscopic) approaches. We, herein, present the first case of robotic removal of a large eroded vaginal mesh into the bladder and discuss potential benefits and limitations of the technique. © 2013 The Japanese Urological Association.

Anterior colporrhaphy versus transvaginal mesh for pelvic-organ prolapse.

Science.gov (United States)

Altman, Daniel; Väyrynen, Tapio; Engh, Marie Ellström; Axelsen, Susanne; Falconer, Christian

2011-05-12

The use of standardized mesh kits for repair of pelvic-organ prolapse has spread rapidly in recent years, but it is unclear whether this approach results in better outcomes than traditional colporrhaphy. In this multicenter, parallel-group, randomized, controlled trial, we compared the use of a trocar-guided, transvaginal polypropylene-mesh repair kit with traditional colporrhaphy in women with prolapse of the anterior vaginal wall (cystocele). The primary outcome was a composite of the objective anatomical designation of stage 0 (no prolapse) or 1 (position of the anterior vaginal wall more than 1 cm above the hymen), according to the Pelvic Organ Prolapse Quantification system, and the subjective absence of symptoms of vaginal bulging 12 months after the surgery. Of 389 women who were randomly assigned to a study treatment, 200 underwent prolapse repair with the transvaginal mesh kit and 189 underwent traditional colporrhaphy. At 1 year, the primary outcome was significantly more common in the women treated with transvaginal mesh repair (60.8%) than in those who underwent colporrhaphy (34.5%) (absolute difference, 26.3 percentage points; 95% confidence interval, 15.6 to 37.0). The surgery lasted longer and the rates of intraoperative hemorrhage were higher in the mesh-repair group than in the colporrhaphy group (Pmesh-repair group and 0.5% in the colporrhaphy group (P=0.07), and the respective rates of new stress urinary incontinence after surgery were 12.3% and 6.3% (P=0.05). Surgical reintervention to correct mesh exposure during follow-up occurred in 3.2% of 186 patients in the mesh-repair group. As compared with anterior colporrhaphy, use of a standardized, trocar-guided mesh kit for cystocele repair resulted in higher short-term rates of successful treatment but also in higher rates of surgical complications and postoperative adverse events. (Funded by the Karolinska Institutet and Ethicon; ClinicalTrials.gov number, NCT00566917.).

Percutaneous Vertebral Augmentation with Polyethylene Mesh and Allograft Bone for Traumatic Thoracolumbar Fractures

Directory of Open Access Journals (Sweden)

C. Schulz

2015-01-01

Full Text Available Purpose. In cases of traumatic thoracolumbar fractures, percutaneous vertebral augmentation can be used in addition to posterior stabilisation. The use of an augmentation technique with a bone-filled polyethylene mesh as a stand-alone treatment for traumatic vertebral fractures has not yet been investigated. Methods. In this retrospective study, 17 patients with acute type A3.1 fractures of the thoracic or lumbar spine underwent stand-alone augmentation with mesh and allograft bone and were followed up for one year using pain scales and sagittal endplate angles. Results. From before surgery to 12 months after surgery, pain and physical function improved significantly, as indicated by an improvement in the median VAS score and in the median pain and work scale scores. From before to immediately after surgery, all patients showed a significant improvement in mean mono- and bisegmental kyphoses. During the one-year period, there was a significant loss of correction. Conclusions. Based on this data a stand-alone approach with vertebral augmentation with polyethylene mesh and allograft bone is not a suitable therapy option for incomplete burst fractures for a young patient collective.

A Unified 3D Mesh Segmentation Framework Based on Markov Random Field

OpenAIRE

Z.F. Shi; L.Y. Lu; D. Le; X.M. Niu

2012-01-01

3D Mesh segmentation has become an important research field in computer graphics during the past decades. Many geometry based and semantic oriented approaches for 3D mesh segmentation has been presented. In this paper, we present a definition of mesh segmentation according to labeling problem. Inspired by the Markov Random Field (MRF) based image segmentation, we propose a new framework of 3D mesh segmentation based on MRF and use graph cuts to solve it. Any features of 3D mesh can be integra...

Development of a multimaterial, two-dimensional, arbitrary Lagrangian-Eulerian mesh computer program

International Nuclear Information System (INIS)

Barton, R.T.

1982-01-01

We have developed a large, multimaterial, two-dimensional Arbitrary Lagrangian-Eulerian (ALE) computer program. The special feature of an ALE mesh is that it can be either an embedded Lagrangian mesh, a fixed Eulerian mesh, or a partially embedded, partially remapped mesh. Remapping is used to remove Lagrangian mesh distortion. This general purpose program has been used for astrophysical modeling, under the guidance of James R. Wilson. The rationale behind the development of this program will be used to highlight several important issues in program design

Clinical and ultrasonographic study of patients presenting with transvaginal mesh complications.

Science.gov (United States)

Manonai, Jittima; Rostaminia, Ghazaleh; Denson, Lindsay; Shobeiri, S Abbas

2016-03-01

The objective of this study was to investigate the clinical and ultrasonographic findings of women who had three-dimensional endovaginal ultrasound (EVUS) for the management of vaginal mesh complications. This was a retrospective study of patients that had EVUS due to mesh complications at a tertiary care center. The clinical charts were reviewed. The stored 3D volumes were reviewed regarding mesh information by two examiners independently. The predictive value of physical examination for detection of vaginal mesh was calculated. Patient outcomes were reviewed. Seventy-nine patients presented to our center because of their, or their physicians' concern regarding mesh complications. Forty-one (51.9%) had vaginal/pelvic pain, and 51/62 (82.2%) of sexually active women experienced dyspareunia. According to ultrasonographic findings, mesh or sling was not demonstrated in six patients who believed they have had mesh/sling implantation. The positive predictive value for vaginal examination was 94.5% (95% CI: 84.9%-98.8%), negative predictive value was 12.5% (95% CI: 2.8%-32.4%), sensitivity was 72.2% (95% CI: 59.4%-81.2%), and specificity was 50.0% (95% CI: 12.4%-87.6%). Fifty-four patients were indicated for surgical treatment. Median postoperative review was 12 (range, 3-18) months and 38/53 (71.7%) patients were satisfied. The most common complaints of vaginal mesh complications were pain and dyspareunia. EVUS appeared to be helpful for assessing mesh presence, location, and extent including planning for surgical intervention. © 2015 Wiley Periodicals, Inc.

Autoclaved Sand-Lime Products with a Polypropylene Mesh

Science.gov (United States)

Kostrzewa, Paulina; Stępień, Anna

2017-10-01

The paper presents the results of the research on modifications of silicate bricks with a polypropylene mesh and their influence on physical, mechanical and microstructural properties of such bricks. The main goal of the paper was to determine effects of the polypropylene mesh on sand-lime product parameters. The analysis has focused on compressive strength, water absorption, bulk density and structural features of the material. The obtained product is characterized by improved basic performance characteristics compared to traditional silicate products. Using the polypropylene mesh increased compressive strength by 25% while decreasing the product density. The modified products retain their form and do not disintegrate after losing their bearing capacity.

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

Prophylactic mesh to prevent parastomal hernia after end colostomy: a meta-analysis and trial sequential analysis.

Science.gov (United States)

López-Cano, M; Brandsma, H-T; Bury, K; Hansson, B; Kyle-Leinhase, I; Alamino, J G; Muysoms, F

2017-04-01

Prevention of parastomal hernia (PSH) formation is crucial, given the high prevalence and difficulties in the surgical repair of PSH. To investigate the effect of a preventive mesh in PSH formation after an end colostomy, we aimed to meta-analyze all relevant randomized controlled trials (RCTs). We searched five databases. For each trial, we extracted risk ratios (RRs) of the effects of mesh or no mesh. The primary outcome was incidence of PSH with a minimum follow-up of 12 months with a clinical and/or computed tomography diagnosis. RRs were combined using the random-effect model (Mantel-Haenszel). To control the risk of type I error, we performed a trial sequential analysis (TSA). Seven RCTs with low risk of bias (451 patients) were included. Meta-analysis for primary outcome showed a significant reduction of the incidence of PSH using a mesh (RR 0.43, 95% CI 0.26-0.71; P = 0.0009). Regarding TSA calculation for the primary outcome, the accrued information size (451) was 187.1% of the estimated required information size (RIS) (241). Wound infection showed no statistical differences between groups (RR 0.77, 95% CI 0.39-1.54; P = 0.46). PSH repair rate showed a significant reduction in the mesh group (RR 0.28 (95% CI 0.10-0.78; P = 0.01). PSH prevention with mesh when creating an end colostomy reduces the incidence of PSH, the risk for subsequent PSH repair and does not increase wound infections. TSA shows that the RIS is reached for the primary outcome. Additional RCTs in the previous context are not needed.

Riding Bare-Back on unstructured meshes for 21. century criticality calculations - 244

International Nuclear Information System (INIS)

Kelley, K.C.; Martz, R.L.; Crane, D.L.

2010-01-01

MCNP has a new capability that permits tracking of neutrons and photons on an unstructured mesh which is embedded as a mesh universe within its legacy geometry capability. The mesh geometry is created through Abaqus/CAE using its solid modeling capabilities. Transport results are calculated for mesh elements through a path length estimator while element to element tracking is performed on the mesh. The results from MCNP can be exported to Abaqus/CAE for visualization or other-physics analysis. The simple Godiva criticality benchmark problem was tested with this new mesh capability. Computer run time is proportional to the number of mesh elements used. Both first and second order polyhedrons are used. Models that used second order polyhedrons produced slightly better results without significantly increasing computer run time. Models that used first order hexahedrons had shorter runtimes than models that used first order tetrahedrons. (authors)

Adaptive mesh generation for image registration and segmentation

DEFF Research Database (Denmark)

Fogtmann, Mads; Larsen, Rasmus

2013-01-01

measure. The method was tested on a T1 weighted MR volume of an adult brain and showed a 66% reduction in the number of mesh vertices compared to a red-subdivision strategy. The deformation capability of the mesh was tested by registration to five additional T1-weighted MR volumes....

Laparoscopy-like operative vaginoscopy: a new approach to manage mesh erosions.

Science.gov (United States)

Billone, Valentina; Amorim-Costa, Célia; Campos, Sara; Rabischong, Benoĭt; Bourdel, Nicolas; Canis, Michel; Botchorishvili, Revaz

2015-01-01

Mesh erosion through the vagina is the most common complication of synthetic mesh used for pelvic organ prolapse repair. However, conventional transvaginal mesh excision has many technical limitations. We aimed at creating and describing a new surgical technique for transvaginal removal of exposed mesh that would enable better exposition and access, thus facilitating optimal treatment. A step-by-step video showing the technique. A university tertiary care hospital. Five patients previously submitted to pelvic organ prolapse repair using synthetic mesh, presenting mesh erosion through the vagina. Mesh excision using a laparoscopy-like operative vaginoscopy in which standard laparoscopic instruments are used through a single-incision laparoscopic surgery port device placed in the vagina. In all cases, a very good exposure of the mesh was achieved, a minimal tissue traction was required, and the procedures were performed in a very ergonomic way. All the patients were discharged on the same day of the surgery and had a painless postoperative course. So far, there have been no cases of relapse. This seems to be a simple, cheap, and valuable minimally invasive technique with many advantages in comparison with the conventional approach. More cases and time are necessary to access its long-term efficacy. It may possibly be used for the management of other conditions. Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

Vertex Normals and Face Curvatures of Triangle Meshes

KAUST Repository

Sun, Xiang; Jiang, Caigui; Wallner, Johannes; Pottmann, Helmut

2016-01-01

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

Recurrence and Pain after Mesh Repair of Inguinal Hernias

African Journals Online (AJOL)

Abstract. Background: Surgery for inguinal hernias has ... repair. Methods: The study was conducted on all inguinal hernia patients operated between 1st. October ... bilateral (1.6%). Only 101 .... Open Mesh Versus Laparoscopic Mesh. Repair ...

MUSIC: a mesh-unrestricted simulation code

International Nuclear Information System (INIS)

Bonalumi, R.A.; Rouben, B.; Dastur, A.R.; Dondale, C.S.; Li, H.Y.H.

1978-01-01

A general formalism to solve the G-group neutron diffusion equation is described. The G-group flux is represented by complementing an ''asymptotic'' mode with (G-1) ''transient'' modes. A particular reduction-to-one-group technique gives a high computational efficiency. MUSIC, a 2-group code using the above formalism, is presented. MUSIC is demonstrated on a fine-mesh calculation and on 2 coarse-mesh core calculations: a heavy-water reactor (HWR) problem and the 2-D lightwater reactor (LWR) IAEA benchmark. Comparison is made to finite-difference results

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.

3D Mesh Compression and Transmission for Mobile Robotic Applications

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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.

22nd International Meshing Roundtable

CERN Document Server

Staten, Matthew

2014-01-01

This volume contains the articles presented at the 22nd International Meshing Roundtable (IMR) organized, in part, by Sandia National Laboratories and was held on Oct 13-16, 2013 in Orlando, Florida, 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.

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.

Kinetic solvers with adaptive mesh in phase space

Science.gov (United States)

Arslanbekov, Robert R.; Kolobov, Vladimir I.; Frolova, Anna A.

2013-12-01

An adaptive mesh in phase space (AMPS) methodology has been developed for solving multidimensional 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” (ToT) data structure. The r mesh is automatically generated around embedded boundaries, and is dynamically adapted to local solution properties. The v mesh is created on-the-fly in each r cell. Mappings between neighboring v-space trees is implemented for the advection operator in r space. We have developed algorithms for solving the full Boltzmann and linear Boltzmann equations with AMPS. Several recent innovations were used to calculate the discrete Boltzmann collision integral with dynamically adaptive v mesh: the importance sampling, multipoint projection, and variance reduction methods. We have developed an efficient algorithm for calculating the linear Boltzmann collision integral for elastic and inelastic collisions of hot light particles in a Lorentz gas. Our AMPS technique has been demonstrated for simulations of hypersonic rarefied gas flows, ion and electron kinetics in weakly ionized plasma, radiation and light-particle transport through thin films, and electron streaming in semiconductors. We have shown that AMPS allows minimizing the number of cells in phase space to reduce the computational cost and memory usage for solving challenging kinetic problems.

An evaluation of the Manufacturer And User Facility Device Experience database that inspired the United States Food and Drug Administration's Reclassification of transvaginal mesh.

Science.gov (United States)

Sandberg, Jason M; Gray, Ian; Pearlman, Amy; Terlecki, Ryan P

2018-03-01

To assess the utility of the Manufacturer And User Facility Device Experience (MAUDE) database in objectively capturing adverse events for transvaginal mesh in the United States. We reviewed 1,103 individual medical device reports submitted to the MAUDE database that inspired the United States (US) Food and Drug Administration's 2008 Public Health Notification. Entries were compiled into a categorical database that reported manufacturer, brand, reporter type, report source, and type of adverse event. There were numerous examples of missing, duplicated, and non-standardized entries. Analysis revealed 64 reports with duplicated information, and six reports representing multiple patients. Forty-seven percent of medical device reports did not identify a reporter source. At least 28% of reported devices are no longer on the US market. There was wide variability in the quality and completeness of submitted reports and true adverse event rates could not be accurately calculated because the number of total cases was unknown. The MAUDE database was limited in its ability to collect, quantify, and standardize real-life adverse events related to transvaginal mesh. While it functions to collect information related to isolated adverse events, systematic limitations of the MAUDE database, that no doubt extend to other medical devices, necessitate the development of new reporting systems. Alternatives are under development, which may allow regulators to more accurately scrutinize the safety profiles of specific medical devices.

Short term post-operative morphing of sacrocolpopexy mesh measured by magnetic resonance imaging.

Science.gov (United States)

Sindhwani, Nikhil; Callewaert, Geertje; Deprest, Thomas; Housmans, Susanne; Van Beckevoort, Dirk; Deprest, Jan

2018-04-01

Sacrocolpopexy (SC) involves suspension of the vaginal vault or cervix to the sacrum using a mesh. Following insertion, the meshes have been observed to have undergone dimensional changes. To quantify dimensional changes of meshes following implantation and characterize their morphology in-vivo. 24 patients underwent SC using PolyVinyliDeneFluoride mesh loaded with Fe 3 O 4 particles. Tailored anterior and posterior mesh flaps were sutured to the respective vaginal walls, uniting at the apex. The posterior flap continued to the sacrum and was attached there. Meshes were visualized on magnetic resonance (MR) imaging at 12 [3-12] (median [range]) months postoperatively and 3D models of the mesh were generated. Dynamic MR sequences were acquired during valsalva to record mesh mobility. The area of the vagina effectively supported by the mesh (Effective Support Area (ESA)) was calculated. The 3D models' wall thickness map was analyzed to identify the locations of mesh folding. Intraclass correlation (ICC) was calculated to test the reliability of the methods. To measure the laxity and flatness of the mesh, the curvature and the ellipticity of the sacral flap were calculated. The ESA calculation methodology had ICC = 0.97. A reduction of 75.49 [61.55-78.67] % (median [IQR]) in area, 47.64 [38.07-59.81] % in anterior flap, and of 23.95 [10.96-27.21] % in the posterior flap was measured. The mesh appeared thicker near its attachment at the sacral promontory (n = 19) and near the vaginal apex (n = 22). The laxity of the mesh was 1.13 [1.10-1.16] and 60.55 [49.76-76.25] % of the sacral flap was flat. We could not reliably measure mesh mobility (ICC = 0.16). A methodology for complete 3D characterization of SC meshes using MR images was presented. After implantation, the supported area is much lower than what is prepared prior to implantation. We propose this happened during the surgery itself. Copyright © 2018 Elsevier Ltd. All rights reserved.

Capacity analysis of wireless mesh networks | Gumel | Nigerian ...

African Journals Online (AJOL)

... number of nodes (n) in a linear topology. The degradation is found to be higher in a fully mesh network as a result of increase in interference and MAC layer contention in the network. Key words: Wireless mesh network (WMN), Adhoc network, Network capacity analysis, Bottleneck collision domain, Medium access control ...

Assessment of Pain and Quality of Life in Lichtenstein Hernia Repair Using a New Monofilament PTFE Mesh: Comparison of Suture vs. Fibrin-Sealant Mesh Fixation.

Science.gov (United States)

Fortelny, René H; Petter-Puchner, Alexander H; Redl, Heinz; May, Christopher; Pospischil, Wolfgang; Glaser, Karl

2014-01-01

Inguinal hernia repair is one of the most common operations in general surgery. The Lichtenstein tension-free operation has become the gold standard in open inguinal hernia repair. Despite the low recurrence rates, pain and discomfort remain a problem for a large number of patients. The aim of this study was to compare suture fixation vs. fibrin sealing by using a new monofilament PTFE mesh, i.e., the Infinit(®) mesh by W. L. Gore & Associates. This study was designed as a controlled prospective single-center two-cohort study. A total of 38 patients were enrolled and operated in Lichtenstein technique either standard suture mesh fixation or fibrin-sealant mesh fixation were used as described in the TIMELI trial. Primary outcome parameters were postoperative complications with the new mesh (i.e., seroma, infection), pain, and quality of life evaluated by the VAS and the SF-36 questionnaire. Secondary outcome was recurrence assessed by ultrasound and physical examination. Follow-up time was 1 year. Significantly, less postoperative pain was reported in the fibrin-sealant group compared to the suture group at 6 weeks (P = 0.035), 6 months (P = 0.023), and 1 year (P = 0.011) postoperatively. Additionally, trends toward a higher postoperative quality of life, a faster surgical procedure, and a shorter hospital stay were seen in the fibrin-sealant group. Fibrin-sealant mesh fixation in Lichtenstein hernioplasty effectively reduces acute and chronic postoperative pain. Monofilament, macro-porous, knitted PTFE meshes seem to be a practicable alternative to commonly used polypropylene meshes in open inguinal hernia repair.

Assessment of pain and quality of life in Lichtenstein hernia repair using a new monofilament PTFE mesh: comparison of suture vs. fibrin sealant mesh fixation

Directory of Open Access Journals (Sweden)

René H Fortelny

2014-11-01

Full Text Available Background: Inguinal hernia repair is one of the most common operations in general surgery. The Lichtenstein tension-free operation has become the gold standard in open inguinal hernia repair. Despite the low recurrence rates, pain and discomfort remain a problem for a large number of patients. The aim of this study was to compare suture fixation vs. fibrin sealing by using a new monofilament PTFE mesh, i.e. the Infinit® mesh by W. L. Gore & Associates. Methods: This study was designed as a controlled prospective single-centre two cohort study. A total of 38 patients were enrolled and operated in Lichtenstein technique either standard suture mesh fixation or fibrin sealant mesh fixation were used as described in the TIMELI trial. Primary outcome parameters were postoperative complications with the new mesh (i.e. seroma, infection, pain and quality of life evaluated by the VAS and the SF-36 questionnaire. Secondary outcome was recurrence assessed by ultrasound and physical examination. Follow-up time was 1 year.Results: Significantly less postoperative pain was reported in the fibrin sealant group compared to the suture group at 6 weeks (P=0.035, 6 months (P=0.023 and 1 year (P=0.011 postoperatively. Additionally trends towards a higher postoperative quality of life, a faster surgical procedure and a shorter hospital stay were seen in the fibrin sealant group.Conclusion: Fibrin sealant mesh fixation in Lichtenstein hernioplasty effectively reduces acute and chronic postoperative pain. Monofilament, macro-porous, knitted PTFE meshes seem to be a practicable alternative to commonly used polypropylene meshes in open inguinal hernia repair.

3D face analysis by using Mesh-LBP feature

Science.gov (United States)

Wang, Haoyu; Yang, Fumeng; Zhang, Yuming; Wu, Congzhong

2017-11-01

Objective: Face Recognition is one of the widely application of image processing. Corresponding two-dimensional limitations, such as the pose and illumination changes, to a certain extent restricted its accurate rate and further development. How to overcome the pose and illumination changes and the effects of self-occlusion is the research hotspot and difficulty, also attracting more and more domestic and foreign experts and scholars to study it. 3D face recognition fusing shape and texture descriptors has become a very promising research direction. Method: Our paper presents a 3D point cloud based on mesh local binary pattern grid (Mesh-LBP), then feature extraction for 3D face recognition by fusing shape and texture descriptors. 3D Mesh-LBP not only retains the integrity of the 3D geometry, is also reduces the need for recognition process of normalization steps, because the triangle Mesh-LBP descriptor is calculated on 3D grid. On the other hand, in view of multi-modal consistency in face recognition advantage, construction of LBP can fusing shape and texture information on Triangular Mesh. In this paper, some of the operators used to extract Mesh-LBP, Such as the normal vectors of the triangle each face and vertex, the gaussian curvature, the mean curvature, laplace operator and so on. Conclusion: First, Kinect devices obtain 3D point cloud face, after the pretreatment and normalization, then transform it into triangular grid, grid local binary pattern feature extraction from face key significant parts of face. For each local face, calculate its Mesh-LBP feature with Gaussian curvature, mean curvature laplace operator and so on. Experiments on the our research database, change the method is robust and high recognition accuracy.

The quasidiffusion method for transport problems on unstructured meshes

Science.gov (United States)

Wieselquist, William A.

2009-06-01

In this work, we develop a quasidiffusion (QD) method for solving radiation transport problems on unstructured quadrilateral meshes in 2D Cartesian geometry, for example hanging-node meshes from adaptive mesh refinement (AMR) applications or skewed quadrilateral meshes from radiation hydrodynamics with Lagrangian meshing. The main result of the work is a new low-order quasidiffusion (LOQD) discretization on arbitrary quadrilaterals and a strategy for the efficient iterative solution which uses Krylov methods and incomplete LU factorization (ILU) preconditioning. The LOQD equations are a non-symmetric set of first-order PDEs that in second-order form resembles convection- diffusion with a diffusion tensor, with the difference that the LOQD equations contain extra cross-derivative terms. Our finite volume (FV) discretization of the LOQD equations is compared with three LOQD discretizations from literature. We then present a conservative, short characteristics discretization based on subcell balances (SCSB) that uses polynomial exponential moments to achieve robust behavior in various limits (e.g. small cells and voids) and is second- order accurate in space. A linear representation of the isotropic component of the scattering source based on face-average and cell-average scalar fluxes is also proposed and shown to be effective in some problems. In numerical tests, our QD method with linear scattering source representation shows some advantages compared to other transport methods. We conclude with avenues for future research and note that this QD method may easily be extended to arbitrary meshes in 3D Cartesian geometry.

The Quick Measure of a Nurbs Surface Curvature for Accurate Triangular Meshing

Directory of Open Access Journals (Sweden)

Kniat Aleksander

2014-04-01

Full Text Available NURBS surfaces are the most widely used surfaces for three-dimensional models in CAD/ CAE programs. When a model for FEM calculation is prepared with a CAD program it is inevitable to mesh it finally. There are many algorithms for meshing planar regions. Some of them may be used for meshing surfaces but it is necessary to take the curvature of the surface under consideration to avoid poor quality mesh. The mesh must be denser in the curved regions of the surface. In this paper, instead of analysing a surface curvature, the method to assess how close is a mesh triangle to the surface to which its vertices belong, is presented. The distance between a mesh triangle and a parallel tangent plane through a point on a surface is the measure of the triangle quality. Finding the surface point whose projection is located inside the mesh triangle and which is the tangency point to the plane parallel to this triangle is an optimization problem. Mathematical description of the problem and the algorithm to find its solution are also presented in the paper.

Fitting polynomial surfaces to triangular meshes with Voronoi squared distance minimization

KAUST Repository

Nivoliers, Vincent

2012-11-06

This paper introduces Voronoi squared distance minimization (VSDM), an algorithm that fits a surface to an input mesh. VSDM minimizes an objective function that corresponds to a Voronoi-based approximation of the overall squared distance function between the surface and the input mesh (SDM). This objective function is a generalization of the one minimized by centroidal Voronoi tessellation, and can be minimized by a quasi-Newton solver. VSDM naturally adapts the orientation of the mesh elements to best approximate the input, without estimating any differential quantities. Therefore, it can be applied to triangle soups or surfaces with degenerate triangles, topological noise and sharp features. Applications of fitting quad meshes and polynomial surfaces to input triangular meshes are demonstrated. © 2012 Springer-Verlag London.

In vitro analysis of biopolymer coating with glycidoxypropyltrimethoxysilane on hernia meshes.

Science.gov (United States)

Metzler, Steffen; Zankovych, Sergiy; Rauchfuß, Falk; Dittmar, Yves; Jandt, Karin; Jandt, Klaus D; Settmacher, Utz; Scheuerlein, Hubert

2017-07-01

Certain coatings may improve the biocompatibility of hernia meshes. The coating with self-assembled monolayers, such as glycidoxypropyltrimethoxysilane (GOPS) can also improve the materials characteristics of implants. This approach was not yet explored in hernia meshes. It was the aim of this work to clarify if and how hernia meshes with their three-dimensional structure can be coated with GOPS and with which technique this coating can be best characterized. Commercially available meshes made from polypropylene (PP), polyester (PE), and expanded polytetrafluorethylene (ePTFE) have been coated with GOPS. The coatings were analyzed via X-ray photoelectron spectroscopy (XPS), confocal laser scanning microscopy (CLSM), and cell proliferation test (mouse fibroblasts). Cell viability and cytotoxicity were tested by MTT test. With the GOPS surface modification, the adherence of mouse fibroblasts on polyester meshes and the proliferation on ePTFE meshes were increased compared to noncoated meshes. Both XPS and CLSM are limited in their applicability and validity due to the three-dimensional mesh structure while CLSM was overall more suitable. In the MTT test, no negative effects of the GOPS coating on the cells were detected after 24 h. The present results show that GOPS coating of hernia meshes is feasible and effective. GOPS coating can be achieved in a fast and cost-efficient way. Further investigations are necessary with respect to coating quality and adverse effects before such a coating may be used in the clinical routine. In conclusion, GOPS is a promising material that warrants further research as coating of medical implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1083-1090, 2017. © 2016 Wiley Periodicals, Inc.

Parallel unstructured mesh optimisation for 3D radiation transport and fluids modelling

International Nuclear Information System (INIS)

Gorman, G.J.; Pain, Ch. C.; Oliveira, C.R.E. de; Umpleby, A.P.; Goddard, A.J.H.

2003-01-01

In this paper we describe the theory and application of a parallel mesh optimisation procedure to obtain self-adapting finite element solutions on unstructured tetrahedral grids. The optimisation procedure adapts the tetrahedral mesh to the solution of a radiation transport or fluid flow problem without sacrificing the integrity of the boundary (geometry), or internal boundaries (regions) of the domain. The objective is to obtain a mesh which has both a uniform interpolation error in any direction and the element shapes are of good quality. This is accomplished with use of a non-Euclidean (anisotropic) metric which is related to the Hessian of the solution field. Appropriate scaling of the metric enables the resolution of multi-scale phenomena as encountered in transient incompressible fluids and multigroup transport calculations. The resulting metric is used to calculate element size and shape quality. The mesh optimisation method is based on a series of mesh connectivity and node position searches of the landscape defining mesh quality which is gauged by a functional. The mesh modification thus fits the solution field(s) in an optimal manner. The parallel mesh optimisation/adaptivity procedure presented in this paper is of general applicability. We illustrate this by applying it to a transient CFD (computational fluid dynamics) problem. Incompressible flow past a cylinder at moderate Reynolds numbers is modelled to demonstrate that the mesh can follow transient flow features. (authors)

Interoperable mesh and geometry tools for advanced petascale simulations

International Nuclear Information System (INIS)

Diachin, L; Bauer, A; Fix, B; Kraftcheck, J; Jansen, K; Luo, X; Miller, M; Ollivier-Gooch, C; Shephard, M S; Tautges, T; Trease, H

2007-01-01

SciDAC applications have a demonstrated need for advanced software tools to manage the complexities associated with sophisticated geometry, mesh, and field manipulation tasks, particularly as computer architectures move toward the petascale. The Center for Interoperable Technologies for Advanced Petascale Simulations (ITAPS) will deliver interoperable and interchangeable mesh, geometry, and field manipulation services that are of direct use to SciDAC applications. The premise of our technology development goal is to provide such services as libraries that can be used with minimal intrusion into application codes. To develop these technologies, we focus on defining a common data model and data-structure neutral interfaces that unify a number of different services such as mesh generation and improvement, front tracking, adaptive mesh refinement, shape optimization, and solution transfer operations. We highlight the use of several ITAPS services in SciDAC applications

Are patient specific meshes required for EIT head imaging?

Science.gov (United States)

Jehl, Markus; Aristovich, Kirill; Faulkner, Mayo; Holder, David

2016-06-01

Head imaging with electrical impedance tomography (EIT) is usually done with time-differential measurements, to reduce time-invariant modelling errors. Previous research suggested that more accurate head models improved image quality, but no thorough analysis has been done on the required accuracy. We propose a novel pipeline for creation of precise head meshes from magnetic resonance imaging and computed tomography scans, which was applied to four different heads. Voltages were simulated on all four heads for perturbations of different magnitude, haemorrhage and ischaemia, in five different positions and for three levels of instrumentation noise. Statistical analysis showed that reconstructions on the correct mesh were on average 25% better than on the other meshes. However, the stroke detection rates were not improved. We conclude that a generic head mesh is sufficient for monitoring patients for secondary strokes following head trauma.

A new fold-cross metal mesh filter for suppressing side lobe leakage in terahertz region

Science.gov (United States)

Lu, Changgui; Qi, Zhengqing; Guo, Wengao; Cui, Yiping

2018-04-01

In this paper we propose a new type of fold-cross metal mesh band pass filter, which keeps diffraction side lobe far away from the main transmission peak and shows much better side lobe suppression. Both experimental and theoretical studies are made to analyze the mechanism of side lobe. Compared to the traditional cross filter, the fold-cross filter has a much lower side lobe with almost the same central frequency, bandwidth and highest transmission about 98%. Using the photolithography and electroplating techniques, we experimentally extend the distance between the main peak and diffraction side lobe to larger than 1 THz for the fold-cross filter, which is two times larger than the cross filter while maintaining the main peak transmissions of 89% at 1.25 THz for the two structures. This type of single layer substrate-free fold-cross metal structure shows better design flexibility and structure reliability with the introduction of fold arms for metal mesh band pass filters.

Mapping method for generating three-dimensional meshes: past and present

International Nuclear Information System (INIS)

Cook, W.A.; Oakes, W.R.

1982-01-01

Two transformations are derived in this paper. One is a mapping of a unit square onto a surve and the other is a mapping of a unit cube onto a three-dimensional region. Two meshing computer programs are then discussed that use these mappings. The first is INGEN, which has been used to calculate three-dimensional meshes for approximately 15 years. This meshing program uses an index scheme to number boundaries, surfaces, and regions. With such an index scheme, it is possible to control nodal points, elements, and boundary conditions. The second is ESCHER, a meshing program now being developed. Two primary considerations governing development of ESCHER are that meshes graded using quadrilaterals are required and that edge-line geometry defined by Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) systems will be a major source of geometry definition. This program separates the processes of nodal-point connectivity generation, computation of nodal-point mapping space coordinates, and mapping of nodal points into model space

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.

Deflating link buffers in a wireless mesh network

KAUST Repository

Jamshaid, Kamran; Shihada, Basem; Showail, Ahmad; Levis, Philip

2014-01-01

We analyze the problem of buffer sizing for backlogged TCP flows in 802.11-based wireless mesh networks. Our objective is to maintain high network utilization while providing low queueing delays. Unlike wired networks where a single link buffer feeds a bottleneck link, the radio spectral resource in a mesh network is shared among a set of contending mesh routers. We account for this by formulating the buffer size problem as sizing a collective buffer distributed over a set of interfering nodes. In this paper we propose mechanisms for sizing and distributing this collective buffer among the mesh nodes constituting the network bottleneck. Our mechanism factors in the network topology and wireless link rates, improving on pre-set buffer allocations that cannot optimally work across the range of configurations achievable with 802.11 radios. We evaluate our mechanisms using simulations as well as experiments on a testbed. Our results show that we can reduce the RTT of a flow by 6× or more, at the cost of less than 10% drop in end-to-end flow throughput.

Deflating link buffers in a wireless mesh network

KAUST Repository

Jamshaid, Kamran

2014-05-01

We analyze the problem of buffer sizing for backlogged TCP flows in 802.11-based wireless mesh networks. Our objective is to maintain high network utilization while providing low queueing delays. Unlike wired networks where a single link buffer feeds a bottleneck link, the radio spectral resource in a mesh network is shared among a set of contending mesh routers. We account for this by formulating the buffer size problem as sizing a collective buffer distributed over a set of interfering nodes. In this paper we propose mechanisms for sizing and distributing this collective buffer among the mesh nodes constituting the network bottleneck. Our mechanism factors in the network topology and wireless link rates, improving on pre-set buffer allocations that cannot optimally work across the range of configurations achievable with 802.11 radios. We evaluate our mechanisms using simulations as well as experiments on a testbed. Our results show that we can reduce the RTT of a flow by 6× or more, at the cost of less than 10% drop in end-to-end flow throughput.

Combined in vivo and ex vivo analysis of mesh mechanics in a porcine hernia model.

Science.gov (United States)

Kahan, Lindsey G; Lake, Spencer P; McAllister, Jared M; Tan, Wen Hui; Yu, Jennifer; Thompson, Dominic; Brunt, L Michael; Blatnik, Jeffrey A

2018-02-01

Hernia meshes exhibit variability in mechanical properties, and their mechanical match to tissue has not been comprehensively studied. We used an innovative imaging model of in vivo strain tracking and ex vivo mechanical analysis to assess effects of mesh properties on repaired abdominal walls in a porcine model. We hypothesized that meshes with dissimilar mechanical properties compared to native tissue would alter abdominal wall mechanics more than better-matched meshes. Seven mini-pigs underwent ventral hernia creation and subsequent open repair with one of two heavyweight polypropylene meshes. Following mesh implantation with attached radio-opaque beads, fluoroscopic images were taken at insufflation pressures from 5 to 30 mmHg on postoperative days 0, 7, and 28. At 28 days, animals were euthanized and ex vivo mechanical testing performed on full-thickness samples across repaired abdominal walls. Testing was conducted on 13 mini-pig controls, and on meshes separately. Stiffness and anisotropy (the ratio of stiffness in the transverse versus craniocaudal directions) were assessed. 3D reconstructions of repaired abdominal walls showed stretch patterns. As pressure increased, both meshes expanded, with no differences between groups. Over time, meshes contracted 17.65% (Mesh A) and 0.12% (Mesh B; p = 0.06). Mesh mechanics showed that Mesh A deviated from anisotropic native tissue more than Mesh B. Compared to native tissue, Mesh A was stiffer both transversely and craniocaudally. Explanted repaired abdominal walls of both treatment groups were stiffer than native tissue. Repaired tissue became less anisotropic over time, as mesh properties prevailed over native abdominal wall properties. This technique assessed 3D stretch at the mesh level in vivo in a porcine model. While the abdominal wall expanded, mesh-ingrown areas contracted, potentially indicating stresses at mesh edges. Ex vivo mechanics demonstrate that repaired tissue adopts mesh properties, suggesting

Mesh size effects on assessments of planktonic hydrozoan abundance and assemblage structure

Science.gov (United States)

Nogueira Júnior, Miodeli; Pukanski, Luis Eduardo de M.; Souza-Conceição, José M.

2015-04-01

The choice of appropriate mesh-size is paramount to accurately quantify planktonic assemblages, however there is no such information available for hydrozoans. Here planktonic hydrozoan abundance and assemblage structure were compared using 200 and 500 μm meshes at Babitonga estuary (S Brazil), throughout a year cycle. Species richness and Shannon-Wiener diversity were higher in the 200 μm mesh, while evenness was typically higher in the 500 μm. Assemblage structure was significantly different between meshes (PERMANOVA, P 8 mm in October. These results suggest that both meshes have their drawbacks and the best choice would depend on the objectives of each study. Nevertheless species richness, total abundances and most taxa were better represented by the 200 μm mesh, suggesting that it is more appropriate to quantitatively sample planktonic hydrozoan assemblages.

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 ...

Lagrangian fluid dynamics using the Voronoi-Delauanay mesh

International Nuclear Information System (INIS)

Dukowicz, J.K.

1981-01-01

A Lagrangian technique for numerical fluid dynamics is described. This technique makes use of the Voronoi mesh to efficiently locate new neighbors, and it uses the dual (Delaunay) triangulation to define computational cells. This removes all topological restrictions and facilitates the solution of problems containing interfaces and multiple materials. To improve computational accuracy a mesh smoothing procedure is employed

Management of complications arising from transvaginal mesh kit procedures: a tertiary referral center's experience.

Science.gov (United States)

Hurtado, Eric A; Appell, Rodney A

2009-01-01

This case series' purpose is to review a referral center's experience with complications from mesh kits. A chart review of 12 patients who presented with complications associated with transvaginal mesh kit procedures was performed. All patients underwent complete surgical removal of the mesh to treat mesh exposure, pain, or vaginal bleeding/discharge followed by an anterior or posterior repair. The mean follow-up time after surgery was 3.4 months. Eight of 12 patients had mesh that had formed a fibrotic band. Six of 12 patients had complete resolution of pain. Of the nine patients with mesh exposure, all required significant resection of the vaginal wall. No further mesh exposure occurred. The use of transvaginal mesh kits may cause previously undescribed complications such as pelvic/vaginal pain or large extrusions requiring complete removal. Removal of all mesh except the arms may cure or significantly improve these problems.

Practical implementation of tetrahedral mesh reconstruction in emission tomography

Science.gov (United States)

Boutchko, R.; Sitek, A.; Gullberg, G. T.

2013-05-01

This paper presents a practical implementation of image reconstruction on tetrahedral meshes optimized for emission computed tomography with parallel beam geometry. Tetrahedral mesh built on a point cloud is a convenient image representation method, intrinsically three-dimensional and with a multi-level resolution property. Image intensities are defined at the mesh nodes and linearly interpolated inside each tetrahedron. For the given mesh geometry, the intensities can be computed directly from tomographic projections using iterative reconstruction algorithms with a system matrix calculated using an exact analytical formula. The mesh geometry is optimized for a specific patient using a two stage process. First, a noisy image is reconstructed on a finely-spaced uniform cloud. Then, the geometry of the representation is adaptively transformed through boundary-preserving node motion and elimination. Nodes are removed in constant intensity regions, merged along the boundaries, and moved in the direction of the mean local intensity gradient in order to provide higher node density in the boundary regions. Attenuation correction and detector geometric response are included in the system matrix. Once the mesh geometry is optimized, it is used to generate the final system matrix for ML-EM reconstruction of node intensities and for visualization of the reconstructed images. In dynamic PET or SPECT imaging, the system matrix generation procedure is performed using a quasi-static sinogram, generated by summing projection data from multiple time frames. This system matrix is then used to reconstruct the individual time frame projections. Performance of the new method is evaluated by reconstructing simulated projections of the NCAT phantom and the method is then applied to dynamic SPECT phantom and patient studies and to a dynamic microPET rat study. Tetrahedral mesh-based images are compared to the standard voxel-based reconstruction for both high and low signal-to-noise ratio

Practical implementation of tetrahedral mesh reconstruction in emission tomography

International Nuclear Information System (INIS)

Boutchko, R; Gullberg, G T; Sitek, A

2013-01-01

This paper presents a practical implementation of image reconstruction on tetrahedral meshes optimized for emission computed tomography with parallel beam geometry. Tetrahedral mesh built on a point cloud is a convenient image representation method, intrinsically three-dimensional and with a multi-level resolution property. Image intensities are defined at the mesh nodes and linearly interpolated inside each tetrahedron. For the given mesh geometry, the intensities can be computed directly from tomographic projections using iterative reconstruction algorithms with a system matrix calculated using an exact analytical formula. The mesh geometry is optimized for a specific patient using a two stage process. First, a noisy image is reconstructed on a finely-spaced uniform cloud. Then, the geometry of the representation is adaptively transformed through boundary-preserving node motion and elimination. Nodes are removed in constant intensity regions, merged along the boundaries, and moved in the direction of the mean local intensity gradient in order to provide higher node density in the boundary regions. Attenuation correction and detector geometric response are included in the system matrix. Once the mesh geometry is optimized, it is used to generate the final system matrix for ML-EM reconstruction of node intensities and for visualization of the reconstructed images. In dynamic PET or SPECT imaging, the system matrix generation procedure is performed using a quasi-static sinogram, generated by summing projection data from multiple time frames. This system matrix is then used to reconstruct the individual time frame projections. Performance of the new method is evaluated by reconstructing simulated projections of the NCAT phantom and the method is then applied to dynamic SPECT phantom and patient studies and to a dynamic microPET rat study. Tetrahedral mesh-based images are compared to the standard voxel-based reconstruction for both high and low signal-to-noise ratio

Enhancing a network coding security scheme to avoid packet dropping in wireless mesh networks / H.L.H.C. Terblanche.

OpenAIRE

Terblanche, Heila Levina Helena Catharina

2013-01-01

With the increase of mobile and smart device usage, the interest in dynamically forming networks is rising. One such type of network isWireless Mesh Networks (WMNs). WMNs are multi-hop networks, with a decentralised nature that can dynamically form into mesh topologies. Network Coding (NC) is a method that is used to increase the efficiency of networks by encoding and decoding data on packet level by means of an XOR operation. NC works well with WMNs because it can exploit WMNs broadcast a...

The long-term behavior of lightweight and heavyweight meshes used to repair abdominal wall defects is determined by the host tissue repair process provoked by the mesh.

Science.gov (United States)

Pascual, Gemma; Hernández-Gascón, Belén; Rodríguez, Marta; Sotomayor, Sandra; Peña, Estefania; Calvo, Begoña; Bellón, Juan M

2012-11-01

Although heavyweight (HW) or lightweight (LW) polypropylene (PP) meshes are widely used for hernia repair, other alternatives have recently appeared. They have the same large-pore structure yet are composed of polytetrafluoroethylene (PTFE). This study compares the long-term (3 and 6 months) behavior of meshes of different pore size (HW compared with LW) and composition (PP compared with PTFE). Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired by the use of a HW or LW PP mesh or a new monofilament, large-pore PTFE mesh (Infinit). At 90 and 180 days after implantation, tissue incorporation, gene and protein expression of neocollagens (reverse transcription-polymerase chain reaction/immunofluorescence), macrophage response (immunohistochemistry), and biomechanical strength were determined. Shrinkage was measured at 90 days. All three meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater in the PTFE implants (P .05). Host collagen deposition is mesh pore size dependent whereas the macrophage response induced is composition dependent with a greater response shown by PTFE. In the long term, macroporous meshes show comparable biomechanical behavior regardless of their pore size or composition. Copyright © 2012 Mosby, Inc. All rights reserved.

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.

Trajectory Optimization Based on Multi-Interval Mesh Refinement Method

Directory of Open Access Journals (Sweden)

Ningbo Li

2017-01-01

Full Text Available In order to improve the optimization accuracy and convergence rate for trajectory optimization of the air-to-air missile, a multi-interval mesh refinement Radau pseudospectral method was introduced. This method made the mesh endpoints converge to the practical nonsmooth points and decreased the overall collocation points to improve convergence rate and computational efficiency. The trajectory was divided into four phases according to the working time of engine and handover of midcourse and terminal guidance, and then the optimization model was built. The multi-interval mesh refinement Radau pseudospectral method with different collocation points in each mesh interval was used to solve the trajectory optimization model. Moreover, this method was compared with traditional h method. Simulation results show that this method can decrease the dimensionality of nonlinear programming (NLP problem and therefore improve the efficiency of pseudospectral methods for solving trajectory optimization problems.

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

A moving mesh finite difference method for equilibrium radiation diffusion equations

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiaobo, E-mail: xwindyb@126.com [Department of Mathematics, College of Science, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Huang, Weizhang, E-mail: whuang@ku.edu [Department of Mathematics, University of Kansas, Lawrence, KS 66045 (United States); Qiu, Jianxian, E-mail: jxqiu@xmu.edu.cn [School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computing, Xiamen University, Xiamen, Fujian 361005 (China)

2015-10-01

An efficient moving mesh finite difference method is developed for the numerical solution of equilibrium radiation diffusion equations in two dimensions. The method is based on the moving mesh partial differential equation approach and moves the mesh continuously in time using a system of meshing partial differential equations. The mesh adaptation is controlled through a Hessian-based monitor function and the so-called equidistribution and alignment principles. Several challenging issues in the numerical solution are addressed. Particularly, the radiation diffusion coefficient depends on the energy density highly nonlinearly. This nonlinearity is treated using a predictor–corrector and lagged diffusion strategy. Moreover, the nonnegativity of the energy density is maintained using a cutoff method which has been known in literature to retain the accuracy and convergence order of finite difference approximation for parabolic equations. Numerical examples with multi-material, multiple spot concentration situations are presented. Numerical results show that the method works well for radiation diffusion equations and can produce numerical solutions of good accuracy. It is also shown that a two-level mesh movement strategy can significantly improve the efficiency of the computation.

A moving mesh finite difference method for equilibrium radiation diffusion equations

International Nuclear Information System (INIS)

Yang, Xiaobo; Huang, Weizhang; Qiu, Jianxian

2015-01-01

An efficient moving mesh finite difference method is developed for the numerical solution of equilibrium radiation diffusion equations in two dimensions. The method is based on the moving mesh partial differential equation approach and moves the mesh continuously in time using a system of meshing partial differential equations. The mesh adaptation is controlled through a Hessian-based monitor function and the so-called equidistribution and alignment principles. Several challenging issues in the numerical solution are addressed. Particularly, the radiation diffusion coefficient depends on the energy density highly nonlinearly. This nonlinearity is treated using a predictor–corrector and lagged diffusion strategy. Moreover, the nonnegativity of the energy density is maintained using a cutoff method which has been known in literature to retain the accuracy and convergence order of finite difference approximation for parabolic equations. Numerical examples with multi-material, multiple spot concentration situations are presented. Numerical results show that the method works well for radiation diffusion equations and can produce numerical solutions of good accuracy. It is also shown that a two-level mesh movement strategy can significantly improve the efficiency of the computation

Tetrahedral meshing via maximal Poisson-disk sampling

KAUST Repository

Guo, Jianwei

2016-02-15

In this paper, we propose a simple yet effective method to generate 3D-conforming tetrahedral meshes from closed 2-manifold surfaces. Our approach is inspired by recent work on maximal Poisson-disk sampling (MPS), which can generate well-distributed point sets in arbitrary domains. We first perform MPS on the boundary of the input domain, we then sample the interior of the domain, and we finally extract the tetrahedral mesh from the samples by using 3D Delaunay or regular triangulation for uniform or adaptive sampling, respectively. We also propose an efficient optimization strategy to protect the domain boundaries and to remove slivers to improve the meshing quality. We present various experimental results to illustrate the efficiency and the robustness of our proposed approach. We demonstrate that the performance and quality (e.g., minimal dihedral angle) of our approach are superior to current state-of-the-art optimization-based approaches.

The Effect of Cyclic Loading on the Mechanical Performance of Surgical Mesh

Directory of Open Access Journals (Sweden)

Ho Y.C.

2010-06-01

Full Text Available Polymeric meshes in the form of knitted nets are commonly used in the surgical repair of pelvic organ prolapses. Although a number of these prosthetic meshes are commercially available, there is little published data on their mechanical performance, in particular on the change in stiffness under the repeated loading experienced in vivo. In this in vitro study, cyclic tensile loading was applied to rectangular strips of four different commercially available meshes. The applied force and resultant displacement was monitored throughout the tests in order to evaluate the change in stiffness. In addition, each mesh was randomly marked using indelible ink in order to permit the use of threedimensional digital image correlation to evaluate local displacements during the tests. However, the scale and form of the deformation experienced by some of the meshes made correlation difficult so that confirmation of the values of stiffness were only obtained for two meshes. The results demonstrate that all the meshes experience an increase in stiffness during cyclic loading, that in most cases cyclic creep occurs and in some cases large-scale, irreversible reorganisation of the mesh structure occurs after as few as 200 cycles at loads of the order of 10N.

Surface orientation effects on bending properties of surgical mesh are independent of tensile properties.

Science.gov (United States)

Simon, David D; Andrews, Sharon M; Robinson-Zeigler, Rebecca; Valdes, Thelma; Woods, Terry O

2018-02-01

Current mechanical testing of surgical mesh focuses primarily on tensile properties even though implanted devices are not subjected to pure tensile loads. Our objective was to determine the flexural (bending) properties of surgical mesh and determine if they correlate with mesh tensile properties. The flexural rigidity values of 11 different surgical mesh designs were determined along three textile directions (machine, cross-machine, and 45° to machine; n = 5 for each) using ASTM D1388-14 while tracking surface orientation. Tensile testing was also performed on the same specimens using ASTM D882-12. Linear regressions were performed to compare mesh flexural rigidity to mesh thickness, areal mass density, filament diameter, ultimate tensile strength, and maximum extension. Of 33 mesh specimen groups, 30 had significant differences in flexural rigidity values when comparing surface orientations (top and bottom). Flexural rigidity and mesh tensile properties also varied with textile direction (machine and cross-machine). There was no strong correlation between the flexural and tensile properties, with mesh thickness having the best overall correlation with flexural rigidity. Currently, surface orientation is not indicated on marketed surgical mesh, and a single mesh may behave differently depending on the direction of loading. The lack of correlation between flexural stiffness and tensile properties indicates the need to examine mesh bending stiffness to provide a more comprehensive understanding of surgical mesh mechanical behaviors. Further investigation is needed to determine if these flexural properties result in the surgical mesh behaving mechanically different depending on implantation direction. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 854-862, 2018. © 2017 Wiley Periodicals, Inc.

Impact of Variable-Resolution Meshes on Regional Climate Simulations

Science.gov (United States)

Fowler, L. D.; Skamarock, W. C.; Bruyere, C. L.

2014-12-01

The Model for Prediction Across Scales (MPAS) is currently being used for seasonal-scale simulations on globally-uniform and regionally-refined meshes. Our ongoing research aims at analyzing simulations of tropical convective activity and tropical cyclone development during one hurricane season over the North Atlantic Ocean, contrasting statistics obtained with a variable-resolution mesh against those obtained with a quasi-uniform mesh. Analyses focus on the spatial distribution, frequency, and intensity of convective and grid-scale precipitations, and their relative contributions to the total precipitation as a function of the horizontal scale. Multi-month simulations initialized on May 1st 2005 using ERA-Interim re-analyses indicate that MPAS performs satisfactorily as a regional climate model for different combinations of horizontal resolutions and transitions between the coarse and refined meshes. Results highlight seamless transitions for convection, cloud microphysics, radiation, and land-surface processes between the quasi-uniform and locally- refined meshes, despite the fact that the physics parameterizations were not developed for variable resolution meshes. Our goal of analyzing the performance of MPAS is twofold. First, we want to establish that MPAS can be successfully used as a regional climate model, bypassing the need for nesting and nudging techniques at the edges of the computational domain as done in traditional regional climate modeling. Second, we want to assess the performance of our convective and cloud microphysics parameterizations as the horizontal resolution varies between the lower-resolution quasi-uniform and higher-resolution locally-refined areas of the global domain.

Developments of DPF systems with mesh laminated structures. Performances of DPF systems which consist of the metal-mesh laminated filter combustion with the alumina-fiber mesh, and the combustion device of trapped diesel particles; Mesh taso kozo no DPF no kaihatsu. Kinzokusen to arumina sen`i mesh ni yoru fukugo filter to filter heiyo heater ni yoru DPF no seino

Energy Technology Data Exchange (ETDEWEB)

Kojima, T; Tange, A; Matsuda, K [NHK Spring Co. Ltd., Yokohama (Japan)

1997-10-01

For the purpose of continuous run without any maintenance, new DPF (diesel particulate filter)systems laminated by both metal-wire mesh and alumina-fiber mesh alternately, are under the developments. The perfect combustion of trapped diesel particulate can be achieved by a couple of the resistance heating devices inserted into the filter. 5 refs., 7 figs., 3 tabs.

Staged Closure of Giant Omphalocele using Synthetic Mesh

OpenAIRE

Parida, Lalit; Pal, Kamalesh; Al Buainain, Hussah; Elshafei, Hossam

2014-01-01

Giant omphalocele is difficult to manage and is associated with a poor outcome. A male newborn presented to our hospital with a giant omphalocele. We performed a staged closure of giant omphalocele using synthetic mesh to construct a silo and then mesh abdominoplasty in the neonatal period that led to a successful outcome within a reasonable period of hospital stay.

An Agent Based Collaborative Simplification of 3D Mesh Model

Science.gov (United States)

Wang, Li-Rong; Yu, Bo; Hagiwara, Ichiro

Large-volume mesh model faces the challenge in fast rendering and transmission by Internet. The current mesh models obtained by using three-dimensional (3D) scanning technology are usually very large in data volume. This paper develops a mobile agent based collaborative environment on the development platform of mobile-C. Communication among distributed agents includes grasping image of visualized mesh model, annotation to grasped image and instant message. Remote and collaborative simplification can be efficiently conducted by Internet.

Assessment of the anti-biofouling potentials of a copper iodide-doped nylon mesh.

Science.gov (United States)

Sato, Tetsuya; Fujimori, Yoshie; Nakayama, Tsuruo; Gotoh, Yasuo; Sunaga, Yoshihiko; Nemoto, Michiko; Matsunaga, Tadashi; Tanaka, Tsuyoshi

2012-08-01

We propose a copper iodide (CuI)-doped nylon mesh prepared using polyiodide ions as a precursor toward anti-biofouling polymer textile. The CuI-doped nylon mesh was subjected to the prevention of biofouling in marine environments. The attachment of the marine organisms was markedly inhibited on the CuI-doped nylon mesh surface until 249 days. Scanning electron microscopy-energy dispersive X-ray analysis indicated that copper compounds were maintained in the nylon mesh after the field experiment, although copper content in the nylon mesh was reduced. Therefore, the copper ions slowly dissolved from nylon mesh will contribute to the long-term prevention of biofouling. Furthermore, electron spin resonance analysis revealed the generation of reactive oxygen species (ROS) from CuI-doped nylon mesh after the field experiment. One of the possibilities for toxic action of copper ions will be the direct effect of Cu+ -induced ROS on biofilm forming on nylon mesh surface. The proposed polymer textile can be applied to fishing and aquafarming nets, mooring rope for ship, or silt fence to restrict polluted water in marine environments.

Reinforcing effect of glass-fiber mesh on complete dentures in a test model with a simulated oral mucosa.

Science.gov (United States)

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

2017-11-01

Studies that evaluated the strength of complete dentures reinforced with glass-fiber mesh or metal mesh on a cast with a simulated oral mucosa are lacking. The purpose of this in vitro study was to compare the mechanical properties of maxillary complete dentures reinforced with glass-fiber mesh with those of metal mesh in a new test model, using a simulated oral mucosa. Complete dentures reinforced with 2 types of glass-fiber mesh, SES mesh (SES) and glass cloth (GC) and metal mesh (metal) were fabricated. Complete dentures without any reinforcement were prepared as a control (n=10). The complete dentures were located on a cast with a simulated oral mucosa, and a load was applied on the posterior artificial teeth bilaterally. The fracture load, elastic modulus, and toughness of a complete denture were measured using a universal testing machine at a crosshead speed of 5 mm/min. The fracture load and elastic modulus were analyzed using 1-way analysis of variance, and the toughness was analyzed with the Kruskal-Wallis test (α=.05). The Tukey multiple range test was used as a post hoc test. The fracture load and toughness of the SES group was significantly higher than that of the metal and control groups (P<.05) but not significantly different from that of the GC group. The elastic modulus of the metal group was significantly higher than that of the control group (P<.05), and no significant differences were observed in the SES and GC groups. Compared with the control group, the fracture load and toughness of the SES and GC groups were higher, while those of the metal group were not significantly different. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A comparative study of onlay and retrorectus mesh placement in incisional hernia repair

Directory of Open Access Journals (Sweden)

Kundan Kharde

2013-01-01

Full Text Available Introduction: Incisional hernia after abdominal surgery is a well-known complication and the incidence of incisional hernias continues to be 2-11% after laparotomy. The repair of incisional hernia has always been a challenge to the surgeon. Various operative techniques for the repair of incisional hernia are in practice; however, the management is not standardized. The retro-rectus mesh placement or the sub-lay technique, popularized by Rives and Stoppa in Europe, has been reported to be quite effective, with low recurrence rates (0-23% and minimal complications. Aims and Objective: The purpose of this study was to compare the traditional on-lay mesh and retro-rectus mesh placement in incisional hernia repairs in terms of time taken for surgery, early complications (wound infections, Mesh extrusion, and Delayed complications (Recurrence. Materials and Methods: This is a prospective study which was conducted in the surgical department of our hospital. A total of 50 cases were included in this study. Of these cases, 25 cases were operated by the on-lay mesh method and 25 by retro-rectus mesh placement. Only the patients with midline hernias up to 10 cm in diameter were included in the study. Result: The operative time for retro-rectus mesh placement was insignificantly higher than that of on-lay mesh repair, whereas, complications like superficial Surgical site infection SSI were identical in both the study groups, but deep SSI leading to infection of mesh was higher in on-lay mesh repair. The recurrence rate was found to be 4% in on-lay mesh repair and 0% in retro-rectus mesh repair. Conclusion: The follow-up period in this study was 6months; hence, late recurrences were not taken into account. However, the low rate of local complications and the low recurrence rate indicate that retro-rectus mesh repair has an advantage over traditional on-lay repair.

Users manual for Opt-MS : local methods for simplicial mesh smoothing and untangling.

Energy Technology Data Exchange (ETDEWEB)

Freitag, L.

1999-07-20

Creating meshes containing good-quality elements is a challenging, yet critical, problem facing computational scientists today. Several researchers have shown that the size of the mesh, the shape of the elements within that mesh, and their relationship to the physical application of interest can profoundly affect the efficiency and accuracy of many numerical approximation techniques. If the application contains anisotropic physics, the mesh can be improved by considering both local characteristics of the approximate application solution and the geometry of the computational domain. If the application is isotropic, regularly shaped elements in the mesh reduce the discretization error, and the mesh can be improved a priori by considering geometric criteria only. The Opt-MS package provides several local node point smoothing techniques that improve elements in the mesh by adjusting grid point location using geometric, criteria. The package is easy to use; only three subroutine calls are required for the user to begin using the software. The package is also flexible; the user may change the technique, function, or dimension of the problem at any time during the mesh smoothing process. Opt-MS is designed to interface with C and C++ codes, ad examples for both two-and three-dimensional meshes are provided.

Form-finding with polyhedral meshes made simple

KAUST Repository

Tang, Chengcheng

2015-08-09

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 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.

Form-finding with polyhedral meshes made simple

KAUST Repository

Tang, Chengcheng; Sun, Xiang; Gomes, Alexandra; Wallner, Johannes; Pottmann, Helmut

2015-01-01

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 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.

Evidence to justify retention of transvaginal mesh: comparison between laparoscopic sacral colpopexy and transvaginal Elevate™ mesh.

Science.gov (United States)

To, Valérie; Hengrasmee, Pattaya; Lam, Alan; Luscombe, Georgina; Lawless, Anna; Lam, Justin

2017-12-01

To determine if laparoscopic sacral colpopexy (LSC) offers better apical support with a lower exposure rate than transvaginal mesh surgery with Elevate™. This was a retrospective cohort study comparing patients with apical prolapse (POP-Q point C ≥ -1) who underwent Elevate™ mesh repair (n = 146) with patients who underwent laparoscopic sacral colpopexy (n = 267). The sacral colpopexy group had a mean age of 59 years and a BMI of 25.7. Patients in the Elevate™ group were older, with a mean age of 63 and a BMI of 26.3. Most of the patients of both groups presented with pelvic organ prolapse stage III (LSC 73.8% and Elevate™ 87.0%) and their mean POP-Q point C were not significantly different (LSC 1.4 vs Elevate™ 1.2 cm). Operative time was longer in the LSC group (113 vs 91 min, p < 0.001), but estimated blood loss was lower (75 cm 3 vs 137 cm 3 , p < 0.001). No difference in mesh exposure rate could be found between the two groups at one year (Elevate™ 0.7% vs LSC 2.6%, OR 0.26, 95% CI 0.03 to 2.10, p = 0.21). One-year objective cure rate, defined as no descent beyond the hymen, was 97.0% in the LSC group and 96.6% in the Elevate™ group (p = .81). The overall recurrence (objective, subjective recurrence or reoperation) was also not different between the groups (LSC 4.5% vs Elevate 4.8%, p = 0.89). Transvaginal Elevate™ mesh delivers comparable apical support with a low exposure rate similar to that of laparoscopic sacral colpopexy.

Electroformation of Giant Vesicles on a Polymer Mesh

Directory of Open Access Journals (Sweden)

Yukihisa Okumura

2011-07-01

Full Text Available Electroformation of cell-sized lipid membrane vesicles (giant vesicles, GVs from egg yolk phosphatidylcholine under applied electric voltage was examined on a substrate of a polymer mesh placed between two planar indium tin oxide coated glass electrodes. Under appropriate conditions, GVs were formed in good yield on meshes of various polymer materials, namely, hydrophobic poly(propylene, poly(ethylene terephthalate, a carbon fiber/nylon composite, and relatively hydrophilic nylon. Arranging threads in a mesh structure with appropriate openings improved GV formation compared to simply increasing the number of threads. For optimal electroformation of GVs, the size and shape of a mesh opening were crucial. With a too large opening, GV formation deteriorated. When the sides of an opening were partially missing, GV formation did not occur efficiently. With an adequate opening, a deposited lipid solution could fill the opening, and a relatively uniform lipid deposit formed on the surface of threads after evaporation of the solvent. This could supply a sufficient amount of lipids to the opening and also prevent a lipid deposit from becoming too thick for electroformation. As a result, good GV formation was often observed in openings filled with swelled lipid.

Electromagnetic interaction of a rotating plasma flow with a conducting mesh

International Nuclear Information System (INIS)

Ikehata, Takashi; Sato, Hirofumi; Iwaya, Tohru; Sato, Naoyuki; Tanabe, Toshio; Mase, Hiroshi

2001-01-01

The effect of a conducting mesh (floating) on the penetrating current (a fraction of discharge current flowing in the downstream across a magnetic field) and the rotational velocity has been investigated and results have been compared with Simpson's model. The velocity was independent of the conductance of the mesh contrary to Simpson's model since the mesh is floating in the present study. (author)

The numerical simulation study of hemodynamics of the new dense-mesh stent

Science.gov (United States)

Ma, Jiali; Yuan, Zhishan; Yu, Xuebao; Feng, Zhaowei; Miao, Weidong; Xu, Xueli; Li, Juntao

2017-09-01

The treatment of aortic aneurysm in new dense mesh stent is based on the principle of hemodynamic changes. But the mechanism is not yet very clear. This paper analyzed and calculated the hemodynamic situation before and after the new dense mesh stent implanting by the method of numerical simulation. The results show the dense mesh stent changed and impacted the blood flow in the aortic aneurysm. The changes include significant decrement of blood velocity, pressure and shear forces, while ensuring blood can supply branches, which means the new dense mesh stent's hemodynamic mechanism in the treatment of aortic aneurysm is clearer. It has very important significance in developing new dense mesh stent in order to cure aortic aneurysm.

A mesh density study for application to large deformation rolling process evaluation

International Nuclear Information System (INIS)

Martin, J.A.

1997-12-01

When addressing large deformation through an elastic-plastic analysis the mesh density is paramount in determining the accuracy of the solution. However, given the nonlinear nature of the problem, a highly-refined mesh will generally require a prohibitive amount of computer resources. This paper addresses finite element mesh optimization studies considering accuracy of results and computer resource needs as applied to large deformation rolling processes. In particular, the simulation of the thread rolling manufacturing process is considered using the MARC software package and a Cray C90 supercomputer. Both mesh density and adaptive meshing on final results for both indentation of a rigid body to a specified depth and contact rolling along a predetermined length are evaluated

Error estimation for goal-oriented spatial adaptivity for the SN equations on triangular meshes

International Nuclear Information System (INIS)

Lathouwers, D.

2011-01-01

In this paper we investigate different error estimation procedures for use within a goal oriented adaptive algorithm for the S N equations on unstructured meshes. The method is based on a dual-weighted residual approach where an appropriate adjoint problem is formulated and solved in order to obtain the importance of residual errors in the forward problem on the specific goal of interest. The forward residuals and the adjoint function are combined to obtain both economical finite element meshes tailored to the solution of the target functional as well as providing error estimates. Various approximations made to make the calculation of the adjoint angular flux more economically attractive are evaluated by comparing the performance of the resulting adaptive algorithm and the quality of the error estimators when applied to two shielding-type test problems. (author)

Deploy production sliding mesh capability with linear solver benchmarking.

Energy Technology Data Exchange (ETDEWEB)

Domino, Stefan P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barone, Matthew F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Williams, Alan B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ananthan, Shreyas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knaus, Robert C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Overfelt, James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sprague, Mike [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rood, Jon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2018-02-01

Wind applications require the ability to simulate rotating blades. To support this use-case, a novel design-order sliding mesh algorithm has been developed and deployed. The hybrid method combines the control volume finite element methodology (CVFEM) with concepts found within a discontinuous Galerkin (DG) finite element method (FEM) to manage a sliding mesh. The method has been demonstrated to be design-order for the tested polynomial basis (P=1 and P=2) and has been deployed to provide production simulation capability for a Vestas V27 (225 kW) wind turbine. Other stationary and canonical rotating ow simulations are also presented. As the majority of wind-energy applications are driving extensive usage of hybrid meshes, a foundational study that outlines near-wall numerical behavior for a variety of element topologies is presented. Results indicate that the proposed nonlinear stabilization operator (NSO) is an effective stabilization methodology to control Gibbs phenomena at large cell Peclet numbers. The study also provides practical mesh resolution guidelines for future analysis efforts. Application-driven performance and algorithmic improvements have been carried out to increase robustness of the scheme on hybrid production wind energy meshes. Specifically, the Kokkos-based Nalu Kernel construct outlined in the FY17/Q4 ExaWind milestone has been transitioned to the hybrid mesh regime. This code base is exercised within a full V27 production run. Simulation timings for parallel search and custom ghosting are presented. As the low-Mach application space requires implicit matrix solves, the cost of matrix reinitialization has been evaluated on a variety of production meshes. Results indicate that at low element counts, i.e., fewer than 100 million elements, matrix graph initialization and preconditioner setup times are small. However, as mesh sizes increase, e.g., 500 million elements, simulation time associated with \\setup-up" costs can increase to nearly 50% of

Prevention of Incisional Hernias with Biological MeshA Systematic Review of the Literature

Directory of Open Access Journals (Sweden)

FILIP ETIENNE MUYSOMS

2016-09-01

Full Text Available Background: Prophylactic mesh augmented reinforcement during closure of abdominal wall incisions has been proposed in patients with increased risk for development of incisional hernias (IH. As part of the BioMesh consensus project, a systematic literature review has been performed to detect those studies where MAR was performed with a non-permanent absorbable mesh (biological or biosynthetic. Methods: A computerized search was performed within 12 databases (Embase, Medline, Web-of-Science, Scopus, Cochrane, CINAHL, Pubmed publisher, Lilacs, Scielo, ScienceDirect, ProQuest, Google scholar with appropriate search terms. Qualitative evaluation was performed using the MINORS score for cohort studies and the Jadad score for RCTs. Results: For midline laparotomy incisions and stoma reversal wounds, 2 RCTs, 2 case control studies and 2 case series were identified. The studies were very heterogeneous in terms of mesh configuration (cross linked versus non cross linked, mesh position (intraperitoneal versus retromuscular versus onlay, surgical indication (gastric bypass versus aortic aneurysm, outcome results (effective versus non effective. After qualitative assessment we have to conclude that the level of evidence on the efficacy and safety of biological meshes for prevention of incisional hernias is very low. No comparative studies were found comparing biological mesh with synthetic non-absorbable meshes for the prevention of incisional hernias. Conclusion: There is no evidence supporting the use of non-permanent absorbable mesh (biological or biosynthetic for prevention of incisional hernias when closing a laparotomy in high-risk patients or in stoma reversal wounds. There is no evidence that a non-permanent absorbable mesh should be preferred to synthetic non-absorbable mesh both in clean or clean-contaminated surgery.

Topological patterns of mesh textures in serpentinites

Science.gov (United States)

Miyazawa, M.; Suzuki, A.; Shimizu, H.; Okamoto, A.; Hiraoka, Y.; Obayashi, I.; Tsuji, T.; Ito, T.

2017-12-01

Serpentinization is a hydration process that forms serpentine minerals and magnetite within the oceanic lithosphere. Microfractures crosscut these minerals during the reactions, and the structures look like mesh textures. It has been known that the patterns of microfractures and the system evolutions are affected by the hydration reaction and fluid transport in fractures and within matrices. This study aims at quantifying the topological patterns of the mesh textures and understanding possible conditions of fluid transport and reaction during serpentinization in the oceanic lithosphere. Two-dimensional simulation by the distinct element method (DEM) generates fracture patterns due to serpentinization. The microfracture patterns are evaluated by persistent homology, which measures features of connected components of a topological space and encodes multi-scale topological features in the persistence diagrams. The persistence diagrams of the different mesh textures are evaluated by principal component analysis to bring out the strong patterns of persistence diagrams. This approach help extract feature values of fracture patterns from high-dimensional and complex datasets.

Improved Mesh_Based Image Morphing ‎

Directory of Open Access Journals (Sweden)

Mohammed Abdullah Taha

2017-11-01

Full Text Available Image morphing is a multi-step process that generates a sequence of transitions between two images. The thought is to get a ₔgrouping of middle pictures which, when ₔassembled with the first pictures would represent the change from one picture to the other.  The process of morphing requires time and attention to detail in order to get good results. Morphing image requires at least two processes warping and cross dissolve. Warping is the process of geometric transformation of images. The cross dissolve is the process interpolation of color of eachₔ pixel from the first image value to theₔ corresponding second imageₔ value over the time. Image morphing techniques differ from in the approach of image warping procedure. This work presents a survey of different techniques to construct morphing images by review the different warping techniques. One of the predominant approaches of warping process is mesh warping which suffers from some problems including ghosting. This work proposed and implements an improved mesh warping technique to construct morphing images. The results show that the proposed approach can overcome the problems of the traditional mesh technique

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.

Parallel paving: An algorithm for generating distributed, adaptive, all-quadrilateral meshes on parallel computers

Energy Technology Data Exchange (ETDEWEB)

Lober, R.R.; Tautges, T.J.; Vaughan, C.T.

1997-03-01

Paving is an automated mesh generation algorithm which produces all-quadrilateral elements. It can additionally generate these elements in varying sizes such that the resulting mesh adapts to a function distribution, such as an error function. While powerful, conventional paving is a very serial algorithm in its operation. Parallel paving is the extension of serial paving into parallel environments to perform the same meshing functions as conventional paving only on distributed, discretized models. This extension allows large, adaptive, parallel finite element simulations to take advantage of paving`s meshing capabilities for h-remap remeshing. A significantly modified version of the CUBIT mesh generation code has been developed to host the parallel paving algorithm and demonstrate its capabilities on both two dimensional and three dimensional surface geometries and compare the resulting parallel produced meshes to conventionally paved meshes for mesh quality and algorithm performance. Sandia`s {open_quotes}tiling{close_quotes} dynamic load balancing code has also been extended to work with the paving algorithm to retain parallel efficiency as subdomains undergo iterative mesh refinement.

Adaptive moving mesh methods for simulating one-dimensional groundwater problems with sharp moving fronts

Science.gov (United States)

Huang, W.; Zheng, Lingyun; Zhan, X.

2002-01-01

Accurate modelling of groundwater flow and transport with sharp moving fronts often involves high computational cost, when a fixed/uniform mesh is used. In this paper, we investigate the modelling of groundwater problems using a particular adaptive mesh method called the moving mesh partial differential equation approach. With this approach, the mesh is dynamically relocated through a partial differential equation to capture the evolving sharp fronts with a relatively small number of grid points. The mesh movement and physical system modelling are realized by solving the mesh movement and physical partial differential equations alternately. The method is applied to the modelling of a range of groundwater problems, including advection dominated chemical transport and reaction, non-linear infiltration in soil, and the coupling of density dependent flow and transport. Numerical results demonstrate that sharp moving fronts can be accurately and efficiently captured by the moving mesh approach. Also addressed are important implementation strategies, e.g. the construction of the monitor function based on the interpolation error, control of mesh concentration, and two-layer mesh movement. Copyright ?? 2002 John Wiley and Sons, Ltd.

Adaptive mesh refinement for storm surge

KAUST Repository

Mandli, Kyle T.; Dawson, Clint N.

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. © 2014 Elsevier Ltd.

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.

Incompressible Navier-Stokes inverse design method based on adaptive unstructured meshes

International Nuclear Information System (INIS)

Rahmati, M.T.; Charlesworth, D.; Zangeneh, M.

2005-01-01

An inverse method for blade design based on Navier-Stokes equations on adaptive unstructured meshes has been developed. In the method, unlike the method based on inviscid equations, the effect of viscosity is directly taken into account. In the method, the pressure (or pressure loading) is prescribed. The design method then computes the blade shape that would accomplish the target prescribed pressure distribution. The method is implemented using a cell-centered finite volume method, which solves the incompressible Navier-Stokes equations on unstructured meshes. An adaptive unstructured mesh method based on grid subdivision and local adaptive mesh method is utilized for increasing the accuracy. (author)

Green Approach to the Fabrication of Superhydrophobic Mesh Surface for Oil/Water Separation.

Science.gov (United States)

Wang, Fajun; Lei, Sheng; Xu, Yao; Ou, Junfei

2015-07-20

We report a simple and environment friendly method to fabricate superhydrophobic metallic mesh surfaces for oil/water separation. The obtained mesh surface exhibits superhydrophobicity and superoleophilicity after it was dried in an oven at 200 °C for 10 min. A rough silver layer is formed on the mesh surface after immersion, and the spontaneous adsorption of airborne carbon contaminants on the silver surface lower the surface free energy of the mesh. No low-surface-energy reagents and/or volatile organic solvents are used. In addition, we demonstrate that by using the mesh box, oils can be separated and collected from the surface of water repeatedly, and that high separation efficiencies of larger than 92 % are retained for various oils. Moreover, the superhydrophobic mesh also possesses excellent corrosion resistance and thermal stability. Hence, these superhydrophobic meshes might be good candidates for the practical separation of oil from the surface of water. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surgical Management of Pelvic floor Prolapse in women using Mesh

African Journals Online (AJOL)

RAH

polytetrafluoroethylene) . This article reviews our experience with polypropylene mesh in pelvic floor repair at the. Southern General Hospital Glasgow. The objective was to determine the safety and effectiveness of the prolene mesh in the repair ...

Divergence-free MHD on unstructured meshes using high order finite volume schemes based on multidimensional Riemann solvers

Science.gov (United States)

Balsara, Dinshaw S.; Dumbser, Michael

2015-10-01

Several advances have been reported in the recent literature on divergence-free finite volume schemes for Magnetohydrodynamics (MHD). Almost all of these advances are restricted to structured meshes. To retain full geometric versatility, however, it is also very important to make analogous advances in divergence-free schemes for MHD on unstructured meshes. Such schemes utilize a staggered Yee-type mesh, where all hydrodynamic quantities (mass, momentum and energy density) are cell-centered, while the magnetic fields are face-centered and the electric fields, which are so useful for the time update of the magnetic field, are centered at the edges. Three important advances are brought together in this paper in order to make it possible to have high order accurate finite volume schemes for the MHD equations on unstructured meshes. First, it is shown that a divergence-free WENO reconstruction of the magnetic field can be developed for unstructured meshes in two and three space dimensions using a classical cell-centered WENO algorithm, without the need to do a WENO reconstruction for the magnetic field on the faces. This is achieved via a novel constrained L2-projection operator that is used in each time step as a postprocessor of the cell-centered WENO reconstruction so that the magnetic field becomes locally and globally divergence free. Second, it is shown that recently-developed genuinely multidimensional Riemann solvers (called MuSIC Riemann solvers) can be used on unstructured meshes to obtain a multidimensionally upwinded representation of the electric field at each edge. Third, the above two innovations work well together with a high order accurate one-step ADER time stepping strategy, which requires the divergence-free nonlinear WENO reconstruction procedure to be carried out only once per time step. The resulting divergence-free ADER-WENO schemes with MuSIC Riemann solvers give us an efficient and easily-implemented strategy for divergence-free MHD on

An efficient approach to unstructured mesh hydrodynamics on the cell broadband engine

Energy Technology Data Exchange (ETDEWEB)

Ferenbaugh, Charles R [Los Alamos National Laboratory

2010-01-01

Unstructured mesh physics for the Cell Broadband Engine (CBE) has received little or no attention to date, largely because the CBE architecture poses particular challenges for unstructured mesh algorithms. The most common SPU memory management strategies cannot be applied to the irregular memory access patterns of unstructured meshes, and the SPU vector instruction set does not support the indirect addressing needed by connectivity arrays. This paper presents an approach to unstructured mesh physics that addresses these challenges, by creating a new mesh data structure and reorganizing code to give efficient CBE performance. The approach is demonstrated on the FLAG production hydrodynamics code using standard test problems, and results show an average speedup of more than 5x over the original code.

Confinement of electron beams by mesh arrays in a relativistic klystron amplifier

International Nuclear Information System (INIS)

Wang Pingshan; Gu Binlin

1998-01-01

Theoretical and experimental results of intense beam confinement by conducting meshes in a relativistic klystron amplifier (RKA) are presented. Electron motions in a steady intense electron beam confined by conducting meshes are analyzed with an approximate space charge field distribution. And the conditions for steady beam transportation are discussed. Experimental results of a long distance (60 cm) transportation of an intense beam (400 kV, 2.5 kA) generated by a linear induction accelerator are presented. Experimental results of modulated beam transportation confined by the mesh array are presented also. The results show that the focusing ability of the conducting meshes is not very sensitive to the beam energy. And the meshes can be used effectively in a RKA to replace the magnetic field system

Pyrolysis-catalysis of waste plastic using a nickel-stainless-steel mesh catalyst for high-value carbon products.

Science.gov (United States)

Zhang, Yeshui; Nahil, Mohamad A; Wu, Chunfei; Williams, Paul T

2017-11-01

A stainless-steel mesh loaded with nickel catalyst was produced and used for the pyrolysis-catalysis of waste high-density polyethylene with the aim of producing high-value carbon products, including carbon nanotubes (CNTs). The catalysis temperature and plastic-to-catalyst ratio were investigated to determine the influence on the formation of different types of carbon deposited on the nickel-stainless-steel mesh catalyst. Increasing temperature from 700 to 900°C resulted in an increase in the carbon deposited on the nickel-loaded stainless-steel mesh catalyst from 32.5 to 38.0 wt%. The increase in sample-to-catalyst ratio reduced the amount of carbon deposited on the mesh catalyst in terms of g carbon g -1 plastic. The carbons were found to be largely composed of filamentous carbons, with negligible disordered (amorphous) carbons. Transmission electron microscopy analysis of the filamentous carbons revealed them to be composed of a large proportion (estimated at ∼40%) multi-walled carbon nanotubes (MWCNTs). The optimum process conditions for CNT production, in terms of yield and graphitic nature, determined by Raman spectroscopy, was catalysis temperature of 800°C and plastic-to-catalyst ratio of 1:2, where a mass of 334 mg of filamentous/MWCNTs g -1 plastic was produced.

Performance evaluation of multi-channel wireless mesh networks with embedded systems.

Science.gov (United States)

Lam, Jun Huy; Lee, Sang-Gon; Tan, Whye Kit

2012-01-01

Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN).

Distributed Cross-layer Monitoring in Wireless Mesh Networks

OpenAIRE

Panmin, Ye; Yong,

2009-01-01

Wireless mesh networks has rapid development over the last few years. However, due to properties such as distributed infrastructure and interference, which strongly affect the performance of wireless mesh networks, developing technology has to face the challenge of architecture and protocol design issues. Traditional layered protocols do not function efficiently in multi-hop wireless environments. To get deeper understanding on interaction of the layered protocols and optimize the performance...

Mesh joinery: a method for building fabricable structures

OpenAIRE

Cignoni, Paolo; Pietroni, Nico; Malomo, Luigi; Scopigno, Roberto

2015-01-01

Mesh joinery is an innovative method to produce illustrative shape approximations suitable for fabrication. Mesh joinery is capable of producing complex fabricable structures in an efficient and visually pleasing manner. We represent an input geometry as a set of planar pieces arranged to compose a rigid structure by exploiting an efficient slit mechanism. Since slices are planar, a standard 2D cutting system is sufficient to fabricate them.

Risk factors of surgical failure following transvaginal mesh repair for the treatment of pelvic organ prolapse.

Science.gov (United States)

Long, Cheng-Yu; Lo, Tsia-Shu; Wang, Chiu-Lin; Wu, Chin-Hu; Liu, Cheng-Min; Su, Juin-Huang

2012-04-01

To identify the factors associated with pelvic organ prolapse (POP) recurrence after transvaginal mesh (TVM) repair. One hundred and thirteen women with symptomatic POP stage II to IV were scheduled for TVM procedures. All subjects underwent urinalyses and pelvic examination using the POP quantification (POP-Q) staging system before and after surgery. Seven (6.2%) of 113 women reported POP recurrence after a mean follow-up time of 30 months. We performed a univariate analysis of patients' characteristics to identify the predictors of surgical failure after TVM. There was no difference between two groups as to body mass index, POP stage, mesh type, and preoperative urinary symptoms and urodynamic parameters (P>0.05). However, we found that uterine prolapse (P=0.016) and surgical experience (P=0.043) were two significant predictors of surgical failure. Multivariate logistic regression showed similar results. Advanced uterine prolapse and lack of surgical experience were two significant predictors of failure following TVM. POP recurrence after mesh repair appears to be unlikely beyond the learning curve. Crown Copyright © 2012. Published by Elsevier Ireland Ltd. All rights reserved.

An evaluation of the Manufacturer And User Facility Device Experience database that inspired the United States Food and Drug Administration's Reclassification of transvaginal mesh

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Jason M. Sandberg

2018-03-01

Full Text Available Purpose: To assess the utility of the Manufacturer And User Facility Device Experience (MAUDE database in objectively capturing adverse events for transvaginal mesh in the United States. Materials and Methods: We reviewed 1,103 individual medical device reports submitted to the MAUDE database that inspired the United States (US Food and Drug Administration's 2008 Public Health Notification. Entries were compiled into a categorical database that reported manufacturer, brand, reporter type, report source, and type of adverse event. Results: There were numerous examples of missing, duplicated, and non-standardized entries. Analysis revealed 64 reports with duplicated information, and six reports representing multiple patients. Forty-seven percent of medical device reports did not identify a reporter source. At least 28% of reported devices are no longer on the US market. There was wide variability in the quality and completeness of submitted reports and true adverse event rates could not be accurately calculated because the number of total cases was unknown. Conclusions: The MAUDE database was limited in its ability to collect, quantify, and standardize real-life adverse events related to transvaginal mesh. While it functions to collect information related to isolated adverse events, systematic limitations of the MAUDE database, that no doubt extend to other medical devices, necessitate the development of new reporting systems. Alternatives are under development, which may allow regulators to more accurately scrutinize the safety profiles of specific medical devices.

A SURVEY on WIRELESS MESH NETWORKS, ROUTING METRICS and PROTOCOLS

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Safak DURUKAN ODABASI

2013-01-01

Full Text Available Today, Internet has become an indispensable part of our daily lives. It has a growing user community in many fields from banking transactions to online entertainment. It will be very efficient for users, as the next generation internet access becomes wireless like frequently used services such as cellular phones. But for providing this, a new network is needed to be designed or an existing network must be improved as well as making changes on infrastructure. At this point, mesh network infrastructure arises and offers more sophisticated internet access with less need. The most important advantage of mesh networks is the capability of working without infrastructure. Mesh networks are an additional access technology more than being a renewed one in the next generation wireless networks called 4G. In this study, wireless mesh networks and example applications are mentioned. Base architecture and design factors are emphasized, current routing protocols that are used on wireless mesh networks and routing metrics on which these protocols are based, are explained. Finally, the performance effects of these protocols and metrics on different network topologies are referred.

An Efficient Approach for Solving Mesh Optimization Problems Using Newton’s Method

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Jibum Kim

2014-01-01

Full Text Available We present an efficient approach for solving various mesh optimization problems. Our approach is based on Newton’s method, which uses both first-order (gradient and second-order (Hessian derivatives of the nonlinear objective function. The volume and surface mesh optimization algorithms are developed such that mesh validity and surface constraints are satisfied. We also propose several Hessian modification methods when the Hessian matrix is not positive definite. We demonstrate our approach by comparing our method with nonlinear conjugate gradient and steepest descent methods in terms of both efficiency and mesh quality.

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.

Three new models for evaluation of standard involute spur gear mesh stiffness

Science.gov (United States)

Liang, Xihui; Zhang, Hongsheng; Zuo, Ming J.; Qin, Yong

2018-02-01

Time-varying mesh stiffness is one of the main internal excitation sources of gear dynamics. Accurate evaluation of gear mesh stiffness is crucial for gear dynamic analysis. This study is devoted to developing new models for spur gear mesh stiffness evaluation. Three models are proposed. The proposed model 1 can give very accurate mesh stiffness result but the gear bore surface must be assumed to be rigid. Enlighted by the proposed model 1, our research discovers that the angular deflection pattern of the gear bore surface of a pair of meshing gears under a constant torque basically follows a cosine curve. Based on this finding, two other models are proposed. The proposed model 2 evaluates gear mesh stiffness by using angular deflections at different circumferential angles of an end surface circle of the gear bore. The proposed model 3 requires using only the angular deflection at an arbitrary circumferential angle of an end surface circle of the gear bore but this model can only be used for a gear with the same tooth profile among all teeth. The proposed models are accurate in gear mesh stiffness evaluation and easy to use. Finite element analysis is used to validate the accuracy of the proposed models.

Prevention of a parastomal hernia by biological mesh reinforcement

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René H Fortelny

2015-10-01

Full Text Available Introduction: In the field of hernia prevention the prophylactic mesh-reinforcement of stoma-sites is one of the most controversially discussed issues. The incidence of parastomal hernias in the literature reported to be up to 48.1% after end colostomy and up to 30.8 % after of loop colostomy respectively, but still remains uncertain due to diagnostic variety of clinical or radiological methods, heterogeneous patient groups and variable follow-up intervals respectively. Anyway, the published data regarding the use of synthetic or bio-prostethic meshes in the prevention of parastomal hernia at the primary operation are very scarce. Methods: A literature search of the Medline database in terms of biological prophylactic mesh implantation in stoma creation identified 6 systematic reviews, 2 randomized controlled trials (RCT, 2 case controlled studies and 1 technical report. Results: In a systematic review focusing on the prevention of parastomal hernia including only RCTs encompassing one RCT using bio-prosthetic mesh the incidence of herniation was 12.5 % compared to 53% in the control group (p<0.0001. In 1 RCT and 2 case control studies respectively, there was a significant smaller incidence of parastomal herniation as well as a similar complication rate compared to the control group respectively. Only in 1 RCT no significant difference regarding the incidence of parastomal hernia was reported with comparable complication rates. Conclusion: Thus so far 2 RCT and 2 case control studies are published with prophylactic bio prosthetic reinforcement in stoma sites. The majority revealed significant better results in terms of parastomal herniation and without any mesh related complications in comparison to the non mesh group. Further multicenter RCT are required to achieve a sufficient level of recommendation.

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…

Energy-efficient wireless mesh networks

CSIR Research Space (South Africa)

Ntlatlapa, N

2007-06-01

Full Text Available This paper outlines the objectives of a recently formed research group at Meraka Institute. The authors consider application of wireless mesh networks in rural infrastructure deficient parts of the African continent where nodes operate on batteries...

A single centre comparative study of laparoscopic mesh rectopexy versus suture rectopexy

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Manash Ranjan Sahoo

2014-01-01

Full Text Available Aim: The aim of our study is to compare the results of laparoscopic mesh vs. suture rectopexy. Materials and Methods: In this retrospective study, 70 patients including both male and female of age ranging between 20 years and 65 years (mean 42.5 yrs were subjected to laparoscopic rectopexy during the period between March 2007 and June 2012, of which 38 patients underwent laparoscopic mesh rectopexy and 32 patients laparoscopic suture rectopexy. These patients were followed up for a mean period of 12 months assessing first bowel movement, hospital stay, duration of surgery, faecal incontinence, constipation, recurrence and morbidity. Results: Duration of surgery was 100.8 ± 12.4 minutes in laparoscopic suture rectopexy and 120 ± 10.8 min in laparoscopic mesh rectopexy. Postoperatively, the mean time for the first bowel movement was 38 hrs and 40 hrs, respectively, for suture and mesh rectopexy. Mean hospital stay was five (range: 4-7 days. There was no significant postoperative complication except for one port site infection in mesh rectopexy group. Patients who had varying degree of incontinence preoperatively showed improvement after surgery. Eleven out of 18 (61.1% patients who underwent laparoscopic suture rectopexy as compared to nine of 19 (47.3% patients who underwent laparoscopic mesh rectopexy improved as regards constipation after surgery. Conclusion: There were no significant difference in both groups who underwent surgery except for patients undergoing suture rectopexy had better symptomatic improvement of continence and constipation. Also, cost of mesh used in laparoscopic mesh rectopexy is absent in lap suture rectopexy group. To conclude that laparoscopic suture rectopexy is a safe and feasible procedure and have comparable results as regards operative time, morbidity, bowel function, cost and recurrence or even slightly better results than mesh rectopexy.

The role of prophylactic cefazolin in the prevention of infection after various types of abdominal wall hernia repair with mesh

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Mostafa Mehrabi Bahar

2015-07-01

Conclusion: Preoperative administration of single-dose cefazolin for prosthetic hernia repairs did not markedly decrease the risk of wound infection. Our results do not support the use of cefazolin as a prophylactic antibiotic for various kinds of abdominal wall hernia repair with mesh.

An Angular Method with Position Control for Block Mesh Squareness Improvement

Energy Technology Data Exchange (ETDEWEB)

Yao, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stillman, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-09-19

We optimize a target function de ned by angular properties with a position control term for a basic stencil with a block-structured mesh, to improve element squareness in 2D and 3D. Comparison with the condition number method shows that besides a similar mesh quality regarding orthogonality can be achieved as the former does, the new method converges faster and provides a more uniform global mesh spacing in our numerical tests.

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

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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.

THE PROGNOSIS OF TOTAL PUBLIC EXPENDITURES AND TYPES OF EXPENDITURES IN ROMANIA

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ANA-PETRINA STANCIU

2012-12-01

Full Text Available The purpose of the paper is to provide a prognosis of total public expenditure and types of expenditures, starting from the evolution in time of total public expenditure and spending on public services, defense, public order and safety, economic affairs, environmental protection, housing and community amenities, health, recreation, culture and religion, education and social protection.