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Sample records for noncoplanar mesh designs

  1. Materials and noncoplanar mesh designs for integrated circuits with linear elastic responses to extreme mechanical deformations.

    Science.gov (United States)

    Kim, Dae-Hyeong; Song, Jizhou; Choi, Won Mook; Kim, Hoon-Sik; Kim, Rak-Hwan; Liu, Zhuangjian; Huang, Yonggang Y; Hwang, Keh-Chih; Zhang, Yong-wei; Rogers, John A

    2008-12-02

    Electronic systems that offer elastic mechanical responses to high-strain deformations are of growing interest because of their ability to enable new biomedical devices and other applications whose requirements are impossible to satisfy with conventional wafer-based technologies or even with those that offer simple bendability. This article introduces materials and mechanical design strategies for classes of electronic circuits that offer extremely high stretchability, enabling them to accommodate even demanding configurations such as corkscrew twists with tight pitch (e.g., 90 degrees in approximately 1 cm) and linear stretching to "rubber-band" levels of strain (e.g., up to approximately 140%). The use of single crystalline silicon nanomaterials for the semiconductor provides performance in stretchable complementary metal-oxide-semiconductor (CMOS) integrated circuits approaching that of conventional devices with comparable feature sizes formed on silicon wafers. Comprehensive theoretical studies of the mechanics reveal the way in which the structural designs enable these extreme mechanical properties without fracturing the intrinsically brittle active materials or even inducing significant changes in their electrical properties. The results, as demonstrated through electrical measurements of arrays of transistors, CMOS inverters, ring oscillators, and differential amplifiers, suggest a valuable route to high-performance stretchable electronics.

  2. 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.

  3. Design and Implementation of the MESH Services Platform

    NARCIS (Netherlands)

    Batteram, Harold J.; Bakker, John-Luc; Verhoosel, Jack P.C.; Diakov, N.K.

    1999-01-01

    Industry acceptance of TINA (Telecommunications Information Networking Architecture) will depend heavily on both the evaluation of working systems that implement this architecture, and on the experiences obtained during the design and implementation of these systems. During the MESH' (Multimedia

  4. 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.

  5. 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.

  6. 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)].

  7. 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)...

  8. 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.

  9. 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)

  10. SU-E-T-514: Investigating the Dose Distributions of Equiangular Spaced Noncoplanar Beams

    International Nuclear Information System (INIS)

    Mitchell, T; Maxim, P; Hadsell, M; Loo, B

    2015-01-01

    Purpose It has been demonstrated that the use of noncoplanar beams in radiation therapy may Result in dose distributions that are comparable or better than standard coplanar beams [Pugachev, 2001]. A radiation therapy system designed with a noncoplanar beam geometry could allow for a full ring diagnostic quality imaging system to be placed around the patient. Additionally, if the noncoplanar beams were fixed in number and in their angle with respect to the patient’s axial plane, then both treatment and imaging could be achieved concurrently without the need for moving parts, which could greatly reduce treatment times. For such a system to be designed, it is necessary to determine the appropriate number of beams and the beam angles to achieve optimal dose distributions. For simplicity, the beam angles are assumed to be equiangular in the patient’s axial plane, and only the beam angle with respect to the axial plane are varied. This study aims to investigate the dose distributions produced by equiangular noncoplanar beams for multiple beam numbers and beam angles, and to compare these dose distributions with distributions achieved in coplanar volumetric arc therapy (VMAT). Methods Dose distributions produced by noncoplanar beams were calculated using the Varian Eclipse treatment planning system by varying the gantry, collimator, and couch angles to simulate the noncoplanar delivery method. Noncoplanar intensity-modulated (NC-IMRT) beams using 8, 12, and 16 beams with angles varying from 45 degrees to 54 with respect to the patient’s axial plane were studied. Results The NC-IMRT beams produced dose distributions comparable to VMAT plans for a number of treatment sites, and were capable of meeting similar dose-volume histogram constraints. Conclusion This study has demonstrated that a noncoplanar beam delivery method with fixed beam numbers and beam angles is capable of delivering dose distributions comparable to VMAT plans currently in use

  11. Reliability optimization design of the gear modification coefficient based on the meshing stiffness

    Science.gov (United States)

    Wang, Qianqian; Wang, Hui

    2018-04-01

    Since the time varying meshing stiffness of gear system is the key factor affecting gear vibration, it is important to design the meshing stiffness to reduce vibration. Based on the effect of gear modification coefficient on the meshing stiffness, considering the random parameters, reliability optimization design of the gear modification is researched. The dimension reduction and point estimation method is used to estimate the moment of the limit state function, and the reliability is obtained by the forth moment method. The cooperation of the dynamic amplitude results before and after optimization indicates that the research is useful for the reduction of vibration and noise and the improvement of the reliability.

  12. Design of personal positioning for coal mine based on mesh

    Energy Technology Data Exchange (ETDEWEB)

    Gao, W.H.; Ma, J.; Kang, L. [Taiyuan University of Science and Technology, Taiyuan (China). College of Electronic Information and Engineering

    2008-07-01

    This paper puts forward a method for a location system for colliery workers based on wireless mesh network combined with zigbee technology which supports IEEE 802.15.4 wireless communication standard, with low power dissipation. Data receipt and transmission by wireless communication is realized by RF chip MC13192 produced by the Freescale company. Data procession and analysis is achieved by an S3C2410A chip manufactured by Sumsung which belongs to the ARM9 16/32 RISC processor.

  13. Dose distribution of non-coplanar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, Toshiharu; Wada, Yoichi; Takenaka, Eiichi

    1987-02-01

    Non-coplanar irradiations were applied to the treatment of brain tumor. The dose distribution around the target area due to non-coplanar irradiation was half less than the dose when coplanar irradiation used. Integral volume dose due to this irradiation was not always less than that due to conventional opposing or rotational irradiation. This irradiation has the better application to the following;as a boost therapy, glioblastoma multiforme;as a radical therapy, recurrent brain tumor, well differentiated brain tumor such as craniopharyngioma, hypophyseal tumor etc and AV-malformation.

  14. Stress adapted embroidered meshes with a graded pattern design for abdominal wall hernia repair

    Science.gov (United States)

    Hahn, J.; Bittrich, L.; Breier, A.; Spickenheuer, A.

    2017-10-01

    Abdominal wall hernias are one of the most relevant injuries of the digestive system with 25 million patients in 2013. Surgery is recommended primarily using allogenic non-absorbable wrap-knitted meshes. These meshes have in common that their stress-strain behaviour is not adapted to the anisotropic behaviour of native abdominal wall tissue. The ideal mesh should possess an adequate mechanical behaviour and a suitable porosity at the same time. An alternative fabrication method to wrap-knitting is the embroidery technology with a high flexibility in pattern design and adaption of mechanical properties. In this study, a pattern generator was created for pattern designs consisting of a base and a reinforcement pattern. The embroidered mesh structures demonstrated different structural and mechanical characteristics. Additionally, the investigation of the mechanical properties exhibited an anisotropic mechanical behaviour for the embroidered meshes. As a result, the investigated pattern generator and the embroidery technology allow the production of stress adapted mesh structures that are a promising approach for hernia reconstruction.

  15. Discussion about the design for mesh data structure within the parallel framework

    International Nuclear Information System (INIS)

    Shi Guangmei; Wu Ruian; Wang Keying; Ji Xiaoyu; Hao Zhiming; Mo Jun; He Yingbo

    2010-01-01

    The mesh data structure, one of the fundamental data structure within the parallel framework, its design and realization level have an effect upon parallel capability of the parallel framework. Through the architecture and the fundamental data structure within some typical parallel framework relatively analyzed, such as JASMIN, SIERRA, and ITAPS, the design thought of parallel framework is discussed. Through borrowing ideas from layered set of services design about the SIERRA Framework, and combining with the objective of PANDA Framework in the near future, this paper present the rudimentary system about PANDA framework layered set of services. On this foundation, detailed introduction is placed in the definition and the management of the mesh data structure that it is located in the underlayer of the PANDA framework. The design and realization about parallel distributed mesh data structure of PANDA are emphatically discussed. The PANDA framework extension and application program development based on PANDA framework are grounded on our efforts.

  16. Noncoplanar VMAT for nasopharyngeal tumors: Plan quality versus treatment time

    International Nuclear Information System (INIS)

    Wild, Esther; Bangert, Mark; Nill, Simeon; Oelfke, Uwe

    2015-01-01

    Purpose: The authors investigated the potential of optimized noncoplanar irradiation trajectories for volumetric modulated arc therapy (VMAT) treatments of nasopharyngeal patients and studied the trade-off between treatment plan quality and delivery time in radiation therapy. Methods: For three nasopharyngeal patients, the authors generated treatment plans for nine different delivery scenarios using dedicated optimization methods. They compared these scenarios according to dose characteristics, number of beam directions, and estimated delivery times. In particular, the authors generated the following treatment plans: (1) a 4π plan, which is a not sequenced, fluence optimized plan that uses beam directions from approximately 1400 noncoplanar directions and marks a theoretical upper limit of the treatment plan quality, (2) a coplanar 2π plan with 72 coplanar beam directions as pendant to the noncoplanar 4π plan, (3) a coplanar VMAT plan, (4) a coplanar step and shoot (SnS) plan, (5) a beam angle optimized (BAO) coplanar SnS IMRT plan, (6) a noncoplanar BAO SnS plan, (7) a VMAT plan with rotated treatment couch, (8) a noncoplanar VMAT plan with an optimized great circle around the patient, and (9) a noncoplanar BAO VMAT plan with an arbitrary trajectory around the patient. Results: VMAT using optimized noncoplanar irradiation trajectories reduced the mean and maximum doses in organs at risk compared to coplanar VMAT plans by 19% on average while the target coverage remains constant. A coplanar BAO SnS plan was superior to coplanar SnS or VMAT; however, noncoplanar plans like a noncoplanar BAO SnS plan or noncoplanar VMAT yielded a better plan quality than the best coplanar 2π plan. The treatment plan quality of VMAT plans depended on the length of the trajectory. The delivery times of noncoplanar VMAT plans were estimated to be 6.5 min in average; 1.6 min longer than a coplanar plan but on average 2.8 min faster than a noncoplanar SnS plan with comparable

  17. Noncoplanar VMAT for nasopharyngeal tumors: Plan quality versus treatment time

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Esther, E-mail: e.wild@dkfz.de; Bangert, Mark [Department of Medical Physics in Radiation Oncology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg (Germany); Nill, Simeon [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG (United Kingdom); Oelfke, Uwe [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, United Kingdom and Department of Medical Physics in Radiation Oncology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg (Germany)

    2015-05-15

    Purpose: The authors investigated the potential of optimized noncoplanar irradiation trajectories for volumetric modulated arc therapy (VMAT) treatments of nasopharyngeal patients and studied the trade-off between treatment plan quality and delivery time in radiation therapy. Methods: For three nasopharyngeal patients, the authors generated treatment plans for nine different delivery scenarios using dedicated optimization methods. They compared these scenarios according to dose characteristics, number of beam directions, and estimated delivery times. In particular, the authors generated the following treatment plans: (1) a 4π plan, which is a not sequenced, fluence optimized plan that uses beam directions from approximately 1400 noncoplanar directions and marks a theoretical upper limit of the treatment plan quality, (2) a coplanar 2π plan with 72 coplanar beam directions as pendant to the noncoplanar 4π plan, (3) a coplanar VMAT plan, (4) a coplanar step and shoot (SnS) plan, (5) a beam angle optimized (BAO) coplanar SnS IMRT plan, (6) a noncoplanar BAO SnS plan, (7) a VMAT plan with rotated treatment couch, (8) a noncoplanar VMAT plan with an optimized great circle around the patient, and (9) a noncoplanar BAO VMAT plan with an arbitrary trajectory around the patient. Results: VMAT using optimized noncoplanar irradiation trajectories reduced the mean and maximum doses in organs at risk compared to coplanar VMAT plans by 19% on average while the target coverage remains constant. A coplanar BAO SnS plan was superior to coplanar SnS or VMAT; however, noncoplanar plans like a noncoplanar BAO SnS plan or noncoplanar VMAT yielded a better plan quality than the best coplanar 2π plan. The treatment plan quality of VMAT plans depended on the length of the trajectory. The delivery times of noncoplanar VMAT plans were estimated to be 6.5 min in average; 1.6 min longer than a coplanar plan but on average 2.8 min faster than a noncoplanar SnS plan with comparable

  18. Architectural and Mobility Management Designs in Internet-Based Infrastructure Wireless Mesh Networks

    Science.gov (United States)

    Zhao, Weiyi

    2011-01-01

    Wireless mesh networks (WMNs) have recently emerged to be a cost-effective solution to support large-scale wireless Internet access. They have numerous applications, such as broadband Internet access, building automation, and intelligent transportation systems. One research challenge for Internet-based WMNs is to design efficient mobility…

  19. Parametric Quadrilateral Meshes for the Design and Optimization of Superconducting Magnets

    CERN Document Server

    Aleksa, Martin; Völlinger, Christine

    2002-01-01

    The program package ROXIE has been developed at CERN for the design and optimization of accelerator magnets. The necessity of extremely uniform fields in the superconducting accelerator magnets for LHC requires very accurate methods of field computation. For this purpose the coupled boundary-element / finite-element technique (BEM-FEM) is used. Quadrilateral higher order finite-element meshes are generated for the discretization of the iron domain (yoke) and stainless steel collars. A new mesh generator using geometrically optimized domain decomposition which was developed at the University of Stuttgart, Germany has been implemented into the ROXIE program providing fully automatic and user friendly mesh generation. The structure of the magnet cross-section can be modeled using parametric objects such as holes of different forms, elliptic, parabolic or hyperbolic arcs, notches, slots, .... For sensitivity analysis and parametric studies, point based morphing algorithms are applied to guarantee smooth adaptatio...

  20. A new design concept for knitted external vein-graft support mesh.

    Science.gov (United States)

    Singh, Charanpreet; Wang, Xungai

    2015-08-01

    Autologous vein-graft failure significantly limits the long-term efficacy of coronary artery bypass procedures. The major cause behind this complication is biomechanical mismatch between the vein and coronary artery. The implanted vein experiences a sudden increase (10-12 fold) in luminal pressures. The resulting vein over-distension or 'ballooning' initiates wall thickening phenomenon and ultimate occlusion. Therefore, a primary goal in improving the longevity of a coronary bypass procedure is to inhibit vein over-distension using mechanical constriction. The idea of using an external vein-graft support mesh has demonstrated sustained benefits and wide acceptance in experimental studies. Nitinol based knitted structures have offered more promising mechanical features than other mesh designs owing to their unique loosely looped construction. However, the conventional plain knit construction still exhibits limitations (radial compliance, deployment ease, flexibility, and bending stresses) which limit this design from proving its real clinical advantage. The new knitted mesh design presented in this study is based on the concept of composite knitting utilising high modulus (nitinol and polyester) and low modulus (polyurethane) material components. The experimental comparison of the new design with a plain knit design demonstrated significant improvement in biomechanical (compliance, flexibility, extensibility, viscoelasticity) and procedural (deployment limit) parameters. The results are indicative of the promising role of new mesh in restoring the lost compliance and pulsatility of vein-graft at high arterial pressures. This way it can assist in controlled vein-graft remodelling and stepwise restoration of vein mechanical homoeostasis. Also, improvement in deployment limit parameter offers more flexibility for a surgeon to use a wide range of vein diameters, which may otherwise be rendered unusable for a plain knit mesh. Copyright © 2015 Elsevier Ltd. All rights

  1. Weyl magnons in noncoplanar stacked kagome antiferromagnets

    Science.gov (United States)

    Owerre, S. A.

    2018-03-01

    Weyl nodes have been experimentally realized in photonic, electronic, and phononic crystals. However, magnonic Weyl nodes are yet to be seen experimentally. In this paper, we propose Weyl magnon nodes in noncoplanar stacked frustrated kagome antiferromagnets, naturally available in various real materials. Most crucially, the Weyl nodes in the current system occur at the lowest excitation and possess a topological thermal Hall effect, therefore they are experimentally accessible at low temperatures due to the population effect of bosonic quasiparticles. In stark contrast to other magnetic systems, the current Weyl nodes do not rely on time-reversal symmetry breaking by the magnetic order. Rather, they result from explicit macroscopically broken time reversal symmetry by the scalar spin chirality of noncoplanar spin textures and can be generalized to chiral spin liquid states. Moreover, the scalar spin chirality gives a real space Berry curvature which is not available in previously studied magnetic Weyl systems. We show the existence of magnon arc surface states connecting projected Weyl magnon nodes on the surface Brillouin zone. We also uncover the first realization of triply-degenerate nodal magnon point in the noncollinear regime with zero scalar spin chirality.

  2. Joint Channel Assignment and Routing in Multiradio Multichannel Wireless Mesh Networks: Design Considerations and Approaches

    Directory of Open Access Journals (Sweden)

    Omar M. Zakaria

    2016-01-01

    Full Text Available Multiradio wireless mesh network is a promising architecture that improves the network capacity by exploiting multiple radio channels concurrently. Channel assignment and routing are underlying challenges in multiradio architectures since both determine the traffic distribution over links and channels. The interdependency between channel assignments and routing promotes toward the joint solutions for efficient configurations. This paper presents an in-depth review of the joint approaches of channel assignment and routing in multiradio wireless mesh networks. First, the key design issues, modeling, and approaches are identified and discussed. Second, existing algorithms for joint channel assignment and routing are presented and classified based on the channel assignment types. Furthermore, the set of reconfiguration algorithms to adapt the network traffic dynamics is also discussed. Finally, the paper presents some multiradio practical implementations and test-beds and points out the future research directions.

  3. Parametric Quadrilateral Meshes for the Design and Optimization of Superconducting Magnets

    CERN Document Server

    Aleksa, Martin; Völlinger, Christine

    2000-01-01

    The program package ROXIE [1] has been developed at CERN for the design and optimization of the superconducting magnets for the LHC.The necessity of extremely uniform (coil dominated) fields in accelerator magnets requires very accurate methods of .eld computation. For this purpose a coupled boundary-element/ finite-element technique (BEM-FEM) is used [2]. Quadrilateral higher order finite-elements are used for the discretization of the iron domain.This is necessary for the accurate modeling of the iron contours and is favorable for 3D meshes. A new quadrilateral mesh generator using geometrically optimized domain decomposition which was developed at the University of Stuttgart, Germany [3] has been implemented into the ROXIE program providing fully automatic and user friendly mesh generation.The frequent application of mathematical optimization techniques requires parametric models which are set-up using a feature-based approach.The structure of the magnet cross-section can be modeled using parametric object...

  4. A Preliminary Design of a Wire Mesh Sensor for Measurement of Void Fraction

    International Nuclear Information System (INIS)

    Hong, Seong Ho; Kim, Jong Hwan; Song, Jin Ho; Hong, Seok Boong

    2006-01-01

    Steam explosion phenomena are accompanied with a multi-dimensional and multi-phase fluid flow and heat transfer phenomena. Void fraction is one of the major parameters, which governs the premixing behavior of melt particles in water and the explosion behavior of the pre-mixed fuel. However, efforts for the development of a reliable measurement technique for void fraction are still underway, as it deals with an interaction between a melt at a very high temperature and water in a short time scale. Hundreds of conductivity type probes installed in a test section enabled monitoring of the evolution of a melt-water interaction zone in the ECO test. A technique using a dual energy X-ray system was developed to measure gas fraction, liquid fraction, and melt fraction simultaneously for a small-scale steam explosion experiment. A high-energy X-ray system for monitoring multi-phase fractions is now being developed at CEA. Recently a measurement of multi-phase fractions by using a wire mesh system has been introduced. It has an advantage that the speed of the measurement is fast and a direct measurement is possible. As a part of a feasibility study on a wire mesh technique for a steam explosion experiment, this paper discusses the design of the wire mesh and the results of the preliminary calibration tests

  5. Design and analysis of a deployable truss for the large modular mesh antenna

    Science.gov (United States)

    Meguro, Akira

    This paper describes the design and deployment analysis for large deployable modular mesh antennas. Key design criteria are deployability, and the driving force and latching moment requirements. Reaction forces and moments due to mesh and cable network seriously influence the driving force. These forces and moments can be precisely estimated by means of analyzing the cable network using Cable Structure Analyzer (CASA). Deployment analysis is carried out using Dynamic Analysis and Design System (DADS). The influence of alignment errors on the driving reaction force can be eliminated by replacing the joint element with a spring element. The joint slop is also modeled using a discontinuous spring elements. Their design approach for three types of deployable modules and the deployment characterstics of three Bread-Board Models based on those designs are also presented. In order to study gravity effects on the deployment characteristics and the effects of the gravity compensation method, ground deployment analysis is carried out. A planned deployment test that will use aircraft parabolic flight to simulate a micro-gravity environment is also described.

  6. Comparison of various spring analogy related mesh deformation techniques in two-dimensional airfoil design optimization

    Science.gov (United States)

    Yang, Y.; Özgen, S.

    2017-06-01

    During the last few decades, CFD (Computational Fluid Dynamics) has developed greatly and has become a more reliable tool for the conceptual phase of aircraft design. This tool is generally combined with an optimization algorithm. In the optimization phase, the need for regenerating the computational mesh might become cumbersome, especially when the number of design parameters is high. For this reason, several mesh generation and deformation techniques have been developed in the past decades. One of the most widely used techniques is the Spring Analogy. There are numerous spring analogy related techniques reported in the literature: linear spring analogy, torsional spring analogy, semitorsional spring analogy, and ball vertex spring analogy. This paper gives the explanation of linear spring analogy method and angle inclusion in the spring analogy method. In the latter case, two di¨erent solution methods are proposed. The best feasible method will later be used for two-dimensional (2D) Airfoil Design Optimization with objective function being to minimize sectional drag for a required lift coe©cient at di¨erent speeds. Design variables used in the optimization include camber and thickness distribution of the airfoil. SU2 CFD is chosen as the §ow solver during the optimization procedure. The optimization is done by using Phoenix ModelCenter Optimization Tool.

  7. Optimal Non-Coplanar Launch to Quick Rendezvous

    National Research Council Canada - National Science Library

    Sears, Gregory

    1997-01-01

    The purpose of this study was to determine the feasibility of launching a Delta Clipper-like vehicle on an optimal, non-coplanar trajectory to rendezvous with an earth orbiting object in one orbit or less...

  8. Design and implementation of a topology control scheme for wireless mesh networks

    CSIR Research Space (South Africa)

    Mudali, P

    2009-09-01

    Full Text Available The Wireless Mesh Network (WMN) backbone is usually comprised of stationary nodes but the transient nature of wireless links results in changing network topologies. Topology Control (TC) aims to preserve network connectivity in ad hoc and mesh...

  9. optimization design of ground grid mesh of 132/33kv substation

    African Journals Online (AJOL)

    user

    INTRODUCTION. Grounding system for transmission substation is very ... drop will occur in mesh which will result in rise of mesh potentials ... minimize the effectiveness of transient voltage. ..... and Grounding in HC and LV Distribution System,.

  10. The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery

    International Nuclear Information System (INIS)

    Yu, Victoria Y.; Tran, Angelia; Nguyen, Dan; Cao, Minsong; Ruan, Dan; Low, Daniel A.; Sheng, Ke

    2015-01-01

    Purpose: Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. Methods: A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy of the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. Results: The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was

  11. The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Victoria Y.; Tran, Angelia; Nguyen, Dan; Cao, Minsong; Ruan, Dan; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edu [Department of Radiation Oncology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90024 (United States)

    2015-11-15

    Purpose: Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. Methods: A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy of the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. Results: The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was

  12. The development and verification of a highly accurate collision prediction model for automated noncoplanar plan delivery.

    Science.gov (United States)

    Yu, Victoria Y; Tran, Angelia; Nguyen, Dan; Cao, Minsong; Ruan, Dan; Low, Daniel A; Sheng, Ke

    2015-11-01

    Significant dosimetric benefits had been previously demonstrated in highly noncoplanar treatment plans. In this study, the authors developed and verified an individualized collision model for the purpose of delivering highly noncoplanar radiotherapy and tested the feasibility of total delivery automation with Varian TrueBeam developer mode. A hand-held 3D scanner was used to capture the surfaces of an anthropomorphic phantom and a human subject, which were positioned with a computer-aided design model of a TrueBeam machine to create a detailed virtual geometrical collision model. The collision model included gantry, collimator, and couch motion degrees of freedom. The accuracy of the 3D scanner was validated by scanning a rigid cubical phantom with known dimensions. The collision model was then validated by generating 300 linear accelerator orientations corresponding to 300 gantry-to-couch and gantry-to-phantom distances, and comparing the corresponding distance measurements to their corresponding models. The linear accelerator orientations reflected uniformly sampled noncoplanar beam angles to the head, lung, and prostate. The distance discrepancies between measurements on the physical and virtual systems were used to estimate treatment-site-specific safety buffer distances with 0.1%, 0.01%, and 0.001% probability of collision between the gantry and couch or phantom. Plans containing 20 noncoplanar beams to the brain, lung, and prostate optimized via an in-house noncoplanar radiotherapy platform were converted into XML script for automated delivery and the entire delivery was recorded and timed to demonstrate the feasibility of automated delivery. The 3D scanner measured the dimension of the 14 cm cubic phantom within 0.5 mm. The maximal absolute discrepancy between machine and model measurements for gantry-to-couch and gantry-to-phantom was 0.95 and 2.97 cm, respectively. The reduced accuracy of gantry-to-phantom measurements was attributed to phantom setup

  13. Design and numerical analysis of an SMA mesh-based self-folding sheet

    International Nuclear Information System (INIS)

    Peraza-Hernandez, Edwin A; Hartl, Darren J; Malak Jr, Richard J

    2013-01-01

    Origami engineering, which is the practice of creating useful three-dimensional structures through folding and fold-like operations applied to initially two-dimensional entities, has the potential to impact several areas of design and manufacturing. In some instances, however, it may be impractical to apply external manipulations to produce the desired folds (e.g., as in remote applications such as space systems). In such cases, self-folding capabilities are valuable. A self-folding material or material system is one that can perform folding operations without manipulations from external forces. This work considers a concept for a self-folding material system. The system extends the ‘programmable matter’ concept and consists of an active, self-morphing sheet composed of two meshes of thermally actuated shape memory alloy (SMA) wire separated by a compliant passive layer. The geometric and power input parameters of the self-folding sheet are optimized to achieve the tightest local fold possible subject to stress and temperature constraints. The sheet folding performance considering folds at different angles relative to the orientation of the wire mesh is also analyzed. The optimization results show that a relatively low elastomer thickness is preferable to generate the tightest fold possible. The results also show that the self-folding sheet does not require large power inputs to achieve an optimal folding performance. It was shown that the self-folding sheet is capable of creating similar quality folds at different orientations. (paper)

  14. 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...

  15. Fast pyrolysis in a novel wire-mesh reactor: design and initial results

    NARCIS (Netherlands)

    Hoekstra, E.; van Swaaij, Willibrordus Petrus Maria; Kersten, Sascha R.A.; Hogendoorn, Kees

    2012-01-01

    Pyrolysis is known to occur by decomposition processes followed by vapour phase reactions. The goal of this research is to develop a novel device to study the initial decomposition processes. For this, a novel wire-mesh reactor was constructed. A small sample (<0.1 g) was clamped between two meshes

  16. Modeling NIF experimental designs with adaptive mesh refinement and Lagrangian hydrodynamics

    Science.gov (United States)

    Koniges, A. E.; Anderson, R. W.; Wang, P.; Gunney, B. T. N.; Becker, R.; Eder, D. C.; MacGowan, B. J.; Schneider, M. B.

    2006-06-01

    Incorporation of adaptive mesh refinement (AMR) into Lagrangian hydrodynamics algorithms allows for the creation of a highly powerful simulation tool effective for complex target designs with three-dimensional structure. We are developing an advanced modeling tool that includes AMR and traditional arbitrary Lagrangian-Eulerian (ALE) techniques. Our goal is the accurate prediction of vaporization, disintegration and fragmentation in National Ignition Facility (NIF) experimental target elements. Although our focus is on minimizing the generation of shrapnel in target designs and protecting the optics, the general techniques are applicable to modern advanced targets that include three-dimensional effects such as those associated with capsule fill tubes. Several essential computations in ordinary radiation hydrodynamics need to be redesigned in order to allow for AMR to work well with ALE, including algorithms associated with radiation transport. Additionally, for our goal of predicting fragmentation, we include elastic/plastic flow into our computations. We discuss the integration of these effects into a new ALE-AMR simulation code. Applications of this newly developed modeling tool as well as traditional ALE simulations in two and three dimensions are applied to NIF early-light target designs.

  17. Modeling NIF Experimental Designs with Adaptive Mesh Refinement and Lagrangian Hydrodynamics

    International Nuclear Information System (INIS)

    Koniges, A E; Anderson, R W; Wang, P; Gunney, B N; Becker, R; Eder, D C; MacGowan, B J

    2005-01-01

    Incorporation of adaptive mesh refinement (AMR) into Lagrangian hydrodynamics algorithms allows for the creation of a highly powerful simulation tool effective for complex target designs with three-dimensional structure. We are developing an advanced modeling tool that includes AMR and traditional arbitrary Lagrangian-Eulerian (ALE) techniques. Our goal is the accurate prediction of vaporization, disintegration and fragmentation in National Ignition Facility (NIF) experimental target elements. Although our focus is on minimizing the generation of shrapnel in target designs and protecting the optics, the general techniques are applicable to modern advanced targets that include three-dimensional effects such as those associated with capsule fill tubes. Several essential computations in ordinary radiation hydrodynamics need to be redesigned in order to allow for AMR to work well with ALE, including algorithms associated with radiation transport. Additionally, for our goal of predicting fragmentation, we include elastic/plastic flow into our computations. We discuss the integration of these effects into a new ALE-AMR simulation code. Applications of this newly developed modeling tool as well as traditional ALE simulations in two and three dimensions are applied to NIF early-light target designs

  18. Modeling Nif experimental designs with adaptive mesh refinement and Lagrangian hydrodynamics

    International Nuclear Information System (INIS)

    Koniges, A.E.; Anderson, R.W.; Wang, P.; Gunney, B.T.N.; Becker, R.; Eder, D.C.; MacGowan, B.J.; Schneider, M.B.

    2006-01-01

    Incorporation of adaptive mesh refinement (AMR) into Lagrangian hydrodynamics algorithms allows for the creation of a highly powerful simulation tool effective for complex target designs with three-dimensional structure. We are developing an advanced modeling tool that includes AMR and traditional arbitrary Lagrangian-Eulerian (ALE) techniques. Our goal is the accurate prediction of vaporization, disintegration and fragmentation in National Ignition Facility (NIF) experimental target elements. Although our focus is on minimizing the generation of shrapnel in target designs and protecting the optics, the general techniques are applicable to modern advanced targets that include three-dimensional effects such as those associated with capsule fill tubes. Several essential computations in ordinary radiation hydrodynamics need to be redesigned in order to allow for AMR to work well with ALE, including algorithms associated with radiation transport. Additionally, for our goal of predicting fragmentation, we include elastic/plastic flow into our computations. We discuss the integration of these effects into a new ALE-AMR simulation code. Applications of this newly developed modeling tool as well as traditional ALE simulations in two and three dimensions are applied to NIF early-light target designs. (authors)

  19. A Cross-Layer Routing Design for Multi-Interface Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Tzu-Chieh Tsai

    2009-01-01

    Full Text Available In recent years, Wireless Mesh Networks (WMNs technologies have received significant attentions. WMNs not only accede to the advantages of ad hoc networks but also provide hierarchical multi-interface architecture. Transmission power control and routing path selections are critical issues in the past researches of multihop networks. Variable transmission power levels lead to different network connectivity and interference. Further, routing path selections among different radio interfaces will also produce different intra-/interflow interference. These features tightly affect the network performance. Most of the related works on the routing protocol design do not consider transmission power control and multi-interface environment simultaneously. In this paper, we proposed a cross-layer routing protocol called M2iRi2 which coordinates transmission power control and intra-/interflow interference considerations as routing metrics. Each radio interface calculates the potential tolerable-added transmission interference in the physical layer. When the route discovery starts, the M2iRi2 will adopt the appropriate power level to evaluate each interface quality along paths. The simulation results demonstrate that our design can enhance both network throughput and end-to-end delay.

  20. Sexual health of ethnic minority MSM in Britain (MESH project: design and methods

    Directory of Open Access Journals (Sweden)

    Low Nicola

    2010-07-01

    Full Text Available Abstract Background Men who have sex with men (MSM remain the group most at risk of acquiring HIV infection in Britain. HIV prevalence appears to vary widely between MSM from different ethnic minority groups in this country for reasons that are not fully understood. The aim of the MESH project was to examine in detail the sexual health of ethnic minority MSM living in Britain. Methods/Design The main objectives of the MESH project were to explore among ethnic minority MSM living in Britain: (i sexual risk behaviour and HIV prevalence; (ii their experience of stigma and discrimination; (iii disclosure of sexuality; (iv use of, and satisfaction with sexual health services; (v the extent to which sexual health services (for treatment and prevention are aware of the needs of ethnic minority MSM. The research was conducted between 2006 and 2008 in four national samples: (i ethnic minority MSM living in Britain; (ii a comparison group of white British MSM living in Britain; (iii NHS sexual health clinic staff in 15 British towns and cities with significant ethnic minority communities and; (iv sexual health promotion/HIV prevention service providers. We also recruited men from two "key migrant" groups living in Britain: MSM born in Central or Eastern Europe and MSM born in Central or South America. Internet-based quantitative and qualitative research methods were used. Ethnic minority MSM were recruited through advertisements on websites, in community venues, via informal networks and in sexual health clinics. White and "key migrant" MSM were recruited mostly through Gaydar, one of the most popular dating sites used by gay men in Britain. MSM who agreed to take part completed a questionnaire online. Ethnic minority MSM who completed the online questionnaire were asked if they would be willing to take part in an online qualitative interview using email. Service providers were identified through the British Association of Sexual Health and HIV (BASHH and

  1. Design of RFID Mesh Network for Electric Vehicle Smart Charging Infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Ching-Yen; Shepelev, Aleksey; Qiu, Charlie; Chu, Chi-Cheng; Gadh, Rajit

    2013-09-04

    With an increased number of Electric Vehicles (EVs) on the roads, charging infrastructure is gaining an ever-more important role in simultaneously meeting the needs of the local distribution grid and of EV users. This paper proposes a mesh network RFID system for user identification and charging authorization as part of a smart charging infrastructure providing charge monitoring and control. The Zigbee-based mesh network RFID provides a cost-efficient solution to identify and authorize vehicles for charging and would allow EV charging to be conducted effectively while observing grid constraints and meeting the needs of EV drivers

  2. 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.

  3. 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.

  4. Toward An Unstructured Mesh Database

    Science.gov (United States)

    Rezaei Mahdiraji, Alireza; Baumann, Peter Peter

    2014-05-01

    Unstructured meshes are used in several application domains such as earth sciences (e.g., seismology), medicine, oceanography, cli- mate modeling, GIS as approximate representations of physical objects. Meshes subdivide a domain into smaller geometric elements (called cells) which are glued together by incidence relationships. The subdivision of a domain allows computational manipulation of complicated physical structures. For instance, seismologists model earthquakes using elastic wave propagation solvers on hexahedral meshes. The hexahedral con- tains several hundred millions of grid points and millions of hexahedral cells. Each vertex node in the hexahedrals stores a multitude of data fields. To run simulation on such meshes, one needs to iterate over all the cells, iterate over incident cells to a given cell, retrieve coordinates of cells, assign data values to cells, etc. Although meshes are used in many application domains, to the best of our knowledge there is no database vendor that support unstructured mesh features. Currently, the main tool for querying and manipulating unstructured meshes are mesh libraries, e.g., CGAL and GRAL. Mesh li- braries are dedicated libraries which includes mesh algorithms and can be run on mesh representations. The libraries do not scale with dataset size, do not have declarative query language, and need deep C++ knowledge for query implementations. Furthermore, due to high coupling between the implementations and input file structure, the implementations are less reusable and costly to maintain. A dedicated mesh database offers the following advantages: 1) declarative querying, 2) ease of maintenance, 3) hiding mesh storage structure from applications, and 4) transparent query optimization. To design a mesh database, the first challenge is to define a suitable generic data model for unstructured meshes. We proposed ImG-Complexes data model as a generic topological mesh data model which extends incidence graph model to multi

  5. Mesh Network Design for Smart Charging Infrastructure and Electric Vehicle Remote Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Shepelev, Aleksey; Chung, Ching-Yen; Chu, Chi-Cheng; Gadh, Rajit

    2013-10-14

    Plug-In Electric Vehicle (PEV) charging today happens with little knowledge of the state of the vehicle being charged. In order to implement smart charging algorithms and other capabilities of the future smart grid, provisions for remote PEV monitoring will have to be developed and tested. The UCLA Smart-grid Energy Research Center (SMERC) is working on a smart charging research platform that includes data acquired in real time from PEVs being charged in order to investigate smart charging algorithms and demand response (DR) strategies for PEVs in large parking garage settings. The system outlined in this work allows PEVs to be remotely monitored throughout the charging process by a smart-charging controller communicating through a mesh network of charging stations and in-vehicle monitoring devices. The approach may be used for Vehicle to Grid (V2G) communication as well as PEV monitoring.

  6. An Interference-Aware Admission Control Design for Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Manikantan Shila Devu

    2010-01-01

    Full Text Available In this paper, we present IAC, an interference aware admission control algorithm for use in wireless mesh networks. The core concept of IAC is to use a low overhead dual threshold based approach to share the bandwidth information with its neighbors in the interfering range. As a result, IAC guarantees that the shared wireless bandwidth is not overutilized and the quality of all existing flows are preserved. Moreover, IAC takes into account the intraflow interference effect to estimate the bandwidth consumption of the flow in a multihop path. We have further proposed two approaches of bandwidth allocation, FCFS and MCU, and demonstrated that proper tuning of thresholds can lead to high performance of both schemes. Simulation results illustrate that IAC effectively limits the overutilization of channel resources which in turn results in high throughput, low delay and low packet loss rate for all admitted flows.

  7. A Multiscale Adaptive Mesh Refinement Approach to Architectured Steel Specification in the Design of a Frameless Stressed Skin Structure

    DEFF Research Database (Denmark)

    Nicholas, Paul; Stasiuk, David; Nørgaard, Esben

    2015-01-01

    This paper describes the development of a modelling approach for the design and fabrication of an incrementally formed, stressed skin metal structure. The term incremental forming refers to a progression of localised plastic deformation to impart 3D form onto a 2D metal sheet, directly from 3D...... design data. A brief introduction presents this fabrication concept, as well as the context of structures whose skin plays a significant structural role. Existing research into ISF privileges either the control of forming parameters to minimise geometric deviation, or the more accurate measurement...... of the impact of the forming process at the scale of the grain. But to enhance structural performance for architectural applications requires that both aspects are considered synthetically. We demonstrate a mesh-based approach that incorporates critical parameters at the scales of structure, element...

  8. Non-coplanar automatic beam orientation selection in cranial IMRT: a practical methodology

    Energy Technology Data Exchange (ETDEWEB)

    Llacer, Jorge [EC Engineering Consultants LLC, 130 Forest Hill Drive, Los Gatos, CA 95032 (United States); Li Sicong [Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE 68198 (United States); Agazaryan, Nzhde; Solberg, Timothy D [Department of Radiation Oncology, University of California, Los Angeles, CA 90095 (United States); Promberger, Claus [BrainLAB AG, Kapellenstrasse 12, 85622 Feldkirchen (Germany)], E-mail: escalivat@jllacer.com, E-mail: sl1@unmc.edu, E-mail: NAgazaryan@mednet.ucla.edu, E-mail: claus.promberger@brainlab.com, E-mail: Timothy.Solberg@utsouthwestern.edu

    2009-03-07

    This paper proposes a method for automatic selection of beam orientations in non-coplanar cranial IMRT. Methods of computer vision, beam's eye view techniques and neural networks are used to define a new geometry-based methodology that leads to treatment plans for cranial lesions that are comparable in quality to those generated by experienced radiation physicists. The automatic beam selection (ABS) process can be carried out in clinically useful computation times, in 1 min or less for most cases. In the process of describing the ABS process, it is shown that the cranial beam orientation optimization problem is mathematically ill posed, with the expectation that a large number of solutions will lead to similar results. Nevertheless, there are better and worse solutions and we show that the proposed ABS process, by its design, has to lead to one of the better ones. We have carried out extensive tests with 14 patients with beam selection tasks ranging from the rather simple to quite complex. The ABS process has always yielded optimizations with results that are considered good for clinic use. Seven-beam coplanar optimizations for some of the patients have also been investigated. Comparisons with non-coplanar optimizations indicate in which cases the simpler coplanar plans can be used to advantage. Parameters used in the comparisons are dose-volume histograms, minimum and maximum PTV doses, equivalent uniform doses for the PTV and OARs, and treatment volume, conformity and normal tissue indices. It is felt that the current ABS methodology is ready for extensive clinical tests.

  9. WING/WORLD: An Open Experimental Toolkit for the Design and Deployment of IEEE 802.11-Based Wireless Mesh Networks Testbeds

    Directory of Open Access Journals (Sweden)

    Daniele Miorandi

    2010-01-01

    Full Text Available Wireless Mesh Networks represent an interesting instance of light-infrastructure wireless networks. Due to their flexibility and resiliency to network failures, wireless mesh networks are particularly suitable for incremental and rapid deployments of wireless access networks in both metropolitan and rural areas. This paper illustrates the design and development of an open toolkit aimed at supporting the design of different solutions for wireless mesh networking by enabling real evaluation, validation, and demonstration. The resulting testbed is based on off-the-shelf hardware components and open-source software and is focused on IEEE 802.11 commodity devices. The software toolkit is based on an “open” philosophy and aims at providing the scientific community with a tool for effective and reproducible performance analysis of WMNs. The paper describes the architecture of the toolkit, and its core functionalities, as well as its potential evolutions.

  10. Novel ventilation design of combining spacer and mesh structure in sports T-shirt significantly improves thermal comfort.

    Science.gov (United States)

    Sun, Chao; Au, Joe Sau-chuen; Fan, Jintu; Zheng, Rong

    2015-05-01

    This paper reports on novel ventilation design in sports T-shirt, which combines spacer and mesh structure, and experimental evidence on the advantages of design in improving thermal comfort. Evaporative resistance (Re) and thermal insulation (Rc) of T-shirts were measured using a sweating thermal manikin under three different air velocities. Moisture permeability index (i(m)) was calculated to compare the different designed T-shirts. The T-shirts of new and conventional designs were also compared by wearer trials, which were comprised of 30 min treadmill running followed by 10 min rest. Skin temperature, skin relative humidity, heart rate, oxygen inhalation and energy expenditure were monitored, and subjective sensations were asked. Results demonstrated that novel T-shirt has 11.1% significant lower im than control sample under windy condition. The novel T-shirt contributes to reduce the variation of skin temperature and relative humidity up to 37% and 32%, as well as decrease 3.3% energy consumption during exercise. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  11. Effectiveness of noncoplanar IMRT planning using a parallelized multiresolution beam angle optimization method for paranasal sinus carcinoma

    International Nuclear Information System (INIS)

    Wang Xiaochun; Zhang Xiaodong; Dong Lei; Liu, Helen; Gillin, Michael; Ahamad, Anesa; Ang Kian; Mohan, Radhe

    2005-01-01

    Purpose: To determine the effectiveness of noncoplanar beam configurations and the benefit of plans using fewer but optimally placed beams designed by a parallelized multiple-resolution beam angle optimization (PMBAO) approach. Methods and Materials: The PMBAO approach uses a combination of coplanar and noncoplanar beam configurations for intensity-modulated radiation therapy (IMRT) treatment planning of paranasal sinus cancers. A smaller number of beams (e.g. 3) are first used to explore the solution space to determine the best and worst beam directions. The results of this exploration are then used as a starting point for determining an optimum beam orientation configuration with more beams (e.g. 5). This process is parallelized using a message passing interface, which greatly reduces the overall computation time for routine clinical practice. To test this approach, treatment for 10 patients with paranasal sinus cancer was planned using a total of 5 beams from a pool of 46 possible beam angles. The PMBAO treatment plans were also compared with IMRT plans designed using 9 equally spaced coplanar beams, which is the standard approach in our clinic. Plans with these two different beam configurations were compared with respect to dose conformity, dose heterogeneity, dose-volume histograms, and doses to organs at risk (i.e., eyes, optic nerve, optic chiasm, and brain). Results: The noncoplanar beam configuration was superior in most paranasal sinus carcinoma cases. The target dose homogeneity was better using a PMBAO 5-beam configuration. However, the dose conformity using PMBAO was not improved and was case dependent. Compared with the 9-beam configuration, the PMBAO configuration significantly reduced the mean dose to the eyes and optic nerves and the maximum dose to the contralateral optical path (e.g. the contralateral eye and optic nerve). The maximum dose to the ipsilateral eye and optic nerve was also lower using the PMBAO configuration than using the 9-beam

  12. Treatment planning evaluation of non-coplanar techniques for conformal radiotherapy of the prostate

    International Nuclear Information System (INIS)

    Bedford, James L.; Henrys, Anthony J.; Dearnaley, David P.; Khoo, Vincent S.

    2005-01-01

    Background and purpose: To evaluate the benefit of using non-coplanar treatment plans for irradiation of two different clinical treatment volumes: prostate only (PO) and the prostate plus seminal vesicles (PSV). Material and methods: An inverse planning algorithm was used to produce three-field, four-field, five-field and six-field non-coplanar treatment plans without intensity-modulation in ten patients. These were compared against a three-field coplanar plan. A dose of 74 Gy was prescribed to the isocentre. Plans were compared using the minimum dose to the planning target volume (PTV), maximum dose to the small bowel, and irradiated volumes of rectum, bladder and femoral head. Biological indices were also evaluated. Results: For the PO group, volume of rectum irradiated to 60 Gy (V 60 ) was 22.5±3.7% for the coplanar plan, and 21.5±5.3% for the five-field non-coplanar plan, which was the most beneficial (p=0.3). For the PSV group, the five-field non-coplanar plan was again the most beneficial. Rectal V 60 was in this case reduced from 41.5±10.4% for the coplanar plan to 35.2±9.3% for the non-coplanar plan (p=0.02). Conclusions: The use of non-coplanar beams in conformal prostate radiotherapy provides a small increase in rectal sparing, more significantly with PSV volumes than for PO volumes

  13. Design and installation of a strategically placed algae mesh barrier at OPG Pickering Nuclear Generating Station

    International Nuclear Information System (INIS)

    Marttila, D.; Patrick, P.; Gregoris, C.

    2009-01-01

    Ontario Power Generation's Pickering Nuclear has experienced a number of events in which attached algae have become entrained in the water intake costing approximately $30M over the 1995-2005 period as a result of deratings, Unit shutdowns and other operational issues. In 2005-2006 OPG and Kinectrics worked collaboratively on evaluating different potential solutions to reduce the impact of algae on the station. One of the solutions developed by Kinectrics included a strategically placed barrier net designed to regulate algae flow into the station intake. In 2006, Kinectrics designed and installed the system, the first of its kind at a Nuclear Power Plant in Canada. The system was operational by May 2007. OPG completed an effectiveness study in 2007 and concluded the barrier system had a beneficial effect on reducing algae impact on the station. (author)

  14. Design process and instrumentation of a low NOx wire-mesh duct burner for micro-cogeneration unit

    Energy Technology Data Exchange (ETDEWEB)

    Ramadan, O.B.; Gauthier, J.E.D. [Carleton Univ., Ottawa, ON (Canada). Dept. of Mechanical and Aerospace Engineering; Hughes, P.M.; Brandon, R. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre

    2007-07-01

    Air pollution and global climate change have become a serious environmental problem leading to increasingly stringent government regulations worldwide. New designs and methods for improving combustion systems to minimize the production of toxic emissions, like nitrogen oxides (NOx) are therefore needed. In order to control smog, acid rain, ozone depletion, and greenhouse-effect warming, a reduction of nitrogen oxide is necessary. One alternative for combined electrical power and heat generation (CHP) are micro-cogeneration units which use a micro-turbine as a prime mover. However, to increase the efficiencies of these units, micro-cogeneration technology still needs to be developed further. This paper described the design process, building, and testing of a new low NOx wire-mesh duct burner (WMDB) for the development of a more efficient micro-cogeneration unit. The primary goal of the study was to develop a practical and simple WMDB, which produces low emissions by using lean-premixed surface combustion concept and its objectives were separated into four phases which were described in this paper. Phase I involved the design and construction of the burner. Phase II involved a qualitative flow visualization study for the duct burner premixer to assist the new design of the burner by introducing an efficient premixer that could be used in this new application. Phase III of this research program involved non-reacting flow modeling on the burner premixer flow field using a commercial computational fluid dynamic model. In phase IV, the reacting flow experimental investigation was performed. It was concluded that the burner successfully increased the quantity and the quality of the heat released from the micro-CHP unit and carbon monoxide emissions of less than 9 ppm were reached. 3 refs., 3 figs.

  15. 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 ...

  16. An Underlay Communication Channel for 5G Cognitive Mesh Networks: Packet Design, Implementation, Analysis, and Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Tarek Haddadin; Stephen Andrew Laraway; Arslan Majid; Taylor Sibbett; Daryl Leon Wasden; Brandon F Lo; Lloyd Landon; David Couch; Hussein Moradi; Behrouz Farhang-Boroujeny

    2016-04-01

    This paper proposes and presents the design and implementation of an underlay communication channel (UCC) for 5G cognitive mesh networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MCSS) signaling. The use of this novel spread spectrum signaling allows the device-to-device (D2D) user equipments (UEs) to communicate at a level well below noise temperature and hence, minimize taxation on macro-cell/small-cell base stations and their UEs in 5G wireless systems. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by macro-cell and small-cell users. Hence, both D2D-to-cellular and cellular-to-D2D interference will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present the detail of an implementation of the proposed transceiver on a software radio platform and compare our experimental results with those from a theoretical analysis of our packet detection algorithm.

  17. Integral dose investigation of non-coplanar treatment beam geometries in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Dan; Dong, Peng; Ruan, Dan; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edu [Department of Radiation Oncology, University of California, Los Angeles, California 90095 (United States); Long, Troy; Romeijn, Edwin [Department of Industrial and Operations, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-01-15

    Purpose: Automated planning and delivery of non-coplanar plans such as 4π radiotherapy involving a large number of fields have been developed to take advantage of the newly available automated couch and gantry on C-arm gantry linacs. However, there is an increasing concern regarding the potential changes in the integral dose that needs to be investigated. Methods: A digital torso phantom and 22 lung and liver stereotactic body radiation therapy (SBRT) patients were included in the study. The digital phantom was constructed as a water equivalent elliptical cylinder with a major axis length of 35.4 cm and minor axis of 23.6 cm. A 4.5 cm diameter target was positioned at varying depths along the major axis. Integral doses from intensity modulated, non-coplanar beams forming a conical pattern were compared against the equally spaced coplanar beam plans. Integral dose dependence on the phantom geometry and the beam number was also quantified. For the patient plans, the non-coplanar and coplanar beams and fluences were optimized using a column generation and pricing approach and compared against clinical VMAT plans using two full (lung) or partial coplanar arcs (liver) entering at the side proximal to the tumor. Both the average dose to the normal tissue volume and the total volumes receiving greater than 2 Gy (V2) and 5 Gy (V5) were evaluated and compared. Results: The ratio of integral dose from the non-coplanar and coplanar plans depended on the tumor depth for the phantom; for tumors shallower than 10 cm, the non-coplanar integral doses were lower than coplanar integral doses for non-coplanar angles less than 60°. Similar patterns were observed in the patient plans. The smallest non-coplanar integral doses were observed for tumor 6–8 cm deep. For the phantom, the integral dose was independent of the number of beams, consistent with the liver SBRT patients but the lung SBRT patients showed slight increase in the integral dose when more beams were used. Larger

  18. [Design and biological evaluation of poly-lactic-co-glycolic acid (PLGA) mesh/collagen-chitosan hybrid scaffold (CCS) as a dermal substitute].

    Science.gov (United States)

    Wang, Xin-Gang; You, Chuan-Gang; Sun, Hua-Feng; Hu, Xin-Lei; Han, Chun-Mao; Zhang, Li-Ping; Zheng, Yu-Rong; Li, Qi-Yin

    2011-02-01

    To design and construct a kind of dermal regeneration template with mesh, and to preliminarily evaluate its biological characteristics. PLGA mesh was integrated into CCS with freeze-drying method for constructing PLGA mesh/CCS composite (PCCS). The micromorphologies and mechanical properties among PLGA mesh, CCS, and PCCS were compared. PCCS and CCS was respectively implanted into subcutaneous tissue of SD rats (PCCS and CCS groups, 9 rats in each group). The tissue samples were collected at post operation week (POW) 1, 2, and 4 for histopathological and immunohistochemical observation. Protein levels of CD68, MPO, IL-1beta, IL-10 were examined by Western blot, with expression of gray value. Data were processed with one-way analysis of variance and t test. Three-dimensional porous structure of PCCS was similar to that of CCS. Mechanical property of PLGA mesh and PCCS was respectively (3.07 +/- 0.10), (3.26 +/- 0.15) MPa, and they were higher than that of CCS [(0.42 +/- 0.21) MPa, F = 592.3, P CCS group were observed at POW 4. A large accumulation of macrophages was observed in both groups, especially at POW 2, and more macrophage infiltration was observed in CCS group. The protein level of IL-10 in PCCS group at POW 2 was obviously higher than that in CCS group, while the protein levels of CD68, MPO, IL-1beta were significantly decreased as compared with those in CCS group (with t value from -4.06 to 2.89, P < 0.05 or P < 0.01). PCCS has excellent mechanical property with appropriate three-dimensional porous structure. Meanwhile, it can rapidly induce formation of new tissue and vascularization, and it has a prospect of serving as a dermal substitute.

  19. 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.

  20. Computer optimization of noncoplanar beam setups improves stereotactic treatment of liver tumors

    International Nuclear Information System (INIS)

    Pooter, Jacco A. de; Mendez Romero, Alejandra; Jansen, Wim; Storchi, Pascal; Woudstra, Evert; Levendag, Peter C.; Heijmen, Ben

    2006-01-01

    Purpose: To investigate whether computer-optimized fully noncoplanar beam setups may improve treatment plans for the stereotactic treatment of liver tumors. Methods: An algorithm for automated beam orientation and weight selection (Cycle) was extended for noncoplanar stereotactic treatments. For 8 liver patients previously treated in our clinic using a prescription isodose of 65%, Cycle was used to generate noncoplanar and coplanar plans with the highest achievable minimum planning target volume (PTV) dose for the clinically delivered isocenter and mean liver doses, while not violating the clinically applied hard planning constraints. The clinical and the optimized coplanar and noncoplanar plans were compared, with respect to D PTV,99% , the dose received by 99% of the PTV, the PTV generalized equivalent uniform dose (gEUD), and the compliance with the clinical constraints. Results: For each patient, the ratio between D PTV,99% and D isoc , and the gEUD -5 and gEUD -2 values of the optimized noncoplanar plan were higher than for the clinical plan with an average increase of respectively 18.8% (range, 7.8-24.0%), 6.4 Gy (range, 3.4-11.8 Gy), and 10.3 Gy (range, 6.7-12.5). D PTV,99% /D isoc , gEUD -5 , and gEUD -2 of the optimized noncoplanar plan was always higher than for the optimized coplanar plan with an average increase of, respectively, 4.5% (range, 0.2-9.7%), 2.7 Gy (range, 0.6-9.7 Gy), and 3.4 Gy (range, 0.6-9.9 Gy). All plans were within the imposed hard constraints. On average, the organs at risk were better spared with the optimized noncoplanar plan than with the optimized coplanar plan and the clinical plan. Conclusions: The use of automatically generated, fully noncoplanar beam setups results in plans that are favorable compared with coplanar techniques. Because of the automation, we found that the planning workload can be decreased from 1 to 2 days to 1 to 2 h

  1. iCycle: Integrated, multicriterial beam angle, and profile optimization for generation of coplanar and noncoplanar IMRT plans

    International Nuclear Information System (INIS)

    Breedveld, Sebastiaan; Storchi, Pascal R. M.; Voet, Peter W. J.; Heijmen, Ben J. M.

    2012-01-01

    Purpose: To introduce iCycle, a novel algorithm for integrated, multicriterial optimization of beam angles, and intensity modulated radiotherapy (IMRT) profiles. Methods: A multicriterial plan optimization with iCycle is based on a prescription called wish-list, containing hard constraints and objectives with ascribed priorities. Priorities are ordinal parameters used for relative importance ranking of the objectives. The higher an objective priority is, the higher the probability that the corresponding objective will be met. Beam directions are selected from an input set of candidate directions. Input sets can be restricted, e.g., to allow only generation of coplanar plans, or to avoid collisions between patient/couch and the gantry in a noncoplanar setup. Obtaining clinically feasible calculation times was an important design criterium for development of iCycle. This could be realized by sequentially adding beams to the treatment plan in an iterative procedure. Each iteration loop starts with selection of the optimal direction to be added. Then, a Pareto-optimal IMRT plan is generated for the (fixed) beam setup that includes all so far selected directions, using a previously published algorithm for multicriterial optimization of fluence profiles for a fixed beam arrangement Breedveld et al.[Phys. Med. Biol. 54, 7199-7209 (2009)]. To select the next direction, each not yet selected candidate direction is temporarily added to the plan and an optimization problem, derived from the Lagrangian obtained from the just performed optimization for establishing the Pareto-optimal plan, is solved. For each patient, a single one-beam, two-beam, three-beam, etc. Pareto-optimal plan is generated until addition of beams does no longer result in significant plan quality improvement. Plan generation with iCycle is fully automated. Results: Performance and characteristics of iCycle are demonstrated by generating plans for a maxillary sinus case, a cervical cancer patient, and a

  2. 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.

  3. Evaluation of volumetric modulated arc therapy for cranial radiosurgery using multiple noncoplanar arcs

    International Nuclear Information System (INIS)

    Audet, Chantal; Poffenbarger, Brett A.; Chang, Pauling; Jackson, Paul S.; Lundahl, Robert E.; Ryu, Stephen I.; Ray, Gordon R.

    2011-01-01

    Purpose: To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. Methods: Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multiple metastases patients were planned (Eclipse RapidArc AAA algorithm, v8.6.15) using VMAT (1-6 noncoplanar arcs), dynamic conformal arc (DCA, ∼4 arcs), and IMRT (nine static fields). All plans were evaluated according to a conformity index (CI), healthy brain tissue doses and volumes, and the dose to organs at risk. A 2D dose distribution was measured (Varian Novalis Tx, HD120 MLC, 1000 MU/min, 6 MV beam) for the ∼4 arc VMAT treatment plans using calibrated film dosimetry. Results: The CI (0-1 best) average for all plans was best for ∼4 noncoplanar arc VMAT at 0.86 compared with ∼0.78 for IMRT and a single arc VMAT and 0.68 for DCA. The volumes of healthy brain receiving 50% of the prescribed target coverage dose or more (V 50% ) were lowest for the four arc VMAT [RA(4)] and DCA plans. The average ratio of the V 50% for the other plans to the RA(4) V 50% were 1.9 for a single noncoplanar arc VMAT [RA(1nc)], 1.4 for single full coplanar arc VMAT [RA(1f)] and 1.3 for IMRT. The V 50% improved significantly for single isocenter multiple metastases plan when two noncoplanar VMAT arcs were added to a full single coplanar one. The maximum dose to 5 cc of the outer 1 cm rim of healthy brain which one may want to keep below nonconsequential doses of 300-400 cGy, was 2-3 times greater for IMRT, RA(1nc) and RA(1f) plans compared with the multiple noncoplanar arc DCA and RA(4) techniques. Organs at risk near (0-4 mm) to targets were best spared by (i) single noncoplanar arcs when the targets are lateral to the organ at risk and (ii) by skewed nonvertical planes of IMRT fields when the targets are not lateral to the organ at risk. The highest dose gradient

  4. SU-F-P-28: A Method of Maximize the Noncoplanar Beam Orientations and Assure the Beam Delivery Clearance for Stereotactic Body Radiation Therapy (SBRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J [Presence St. Joseph Medical Ctr., Joliet, IL (United States)

    2016-06-15

    Purpose: Develop a method to maximize the noncoplanar beam orientations and assure the beam delivery clearance for SBRT, therefore, optimize the dose conformality to the target, increase the dose sparing to the critical normal organs and reduce the hot spots in the body. Methods: A SBRT body frame (Elekta, Stockholm, Sweden) was used for patient immobilization and target localization. The SBRT body frame has CT fiducials on its side frames. After patient’s CT scan, the radiation treatment isocenter was defined and its coordinators referring to the body frame was calculated in the radiation treatment planning process. Meanwhile, initial beam orientations were designed based on the patient target and critical organ anatomy. The body frame was put on the linear accelerator couch and positioned to the calculated isocenter. Initially designed beam orientations were manually measured by tuning the body frame position on the couch, the gantry and couch angles. The finalized beam orientations were put into the treatment planning for dosimetric calculations. Results: Without patient presence, an optimal set of beam orientations were designed and validated. The radiation treatment plan was optimized and guaranteed for delivery clearance. Conclusion: The developed method is beneficial and effective in SBRT treatment planning for individual patient. It first allows maximizing the achievable noncoplanar beam orientation space, therefore, optimize the treatment plan for specific patient. It eliminates the risk that a plan needs to be modified due to the gantry and couch collision during patient setup.

  5. Comparison of a new noncoplanar intensity-modulated radiation therapy technique for craniospinal irradiation with 3 coplanar techniques

    DEFF Research Database (Denmark)

    Hansen, Anders T; Lukacova, Slavka; Lassen-Ramshad, Yasmin A.

    2015-01-01

    When standard conformal x-ray technique for craniospinal irradiation is used, it is a challenge to achieve satisfactory dose coverage of the target including the area of the cribriform plate, while sparing organs at risk. We present a new intensity-modulated radiation therapy (IMRT), noncoplanar...... patient using the noncoplanar IMRT-based technique, a coplanar IMRT-based technique, and a coplanar volumetric-modulated arch therapy (VMAT) technique. Dosimetry data for all patients were compared with the corresponding data from the conventional treatment plans. The new noncoplanar IMRT technique...... substantially reduced the mean dose to organs at risk compared with the standard radiation technique. The 2 other coplanar techniques also reduced the mean dose to some of the critical organs. However, this reduction was not as substantial as the reduction obtained by the noncoplanar technique. Furthermore...

  6. Usefulness of Non-coplanar Helical Tomotherapy Using Variable Axis Baseplate

    International Nuclear Information System (INIS)

    Ha, Jin Sook; Chung, Yoon Sun; Lee, Ik Jae; Shin, Dong Bong; Kim, Jong Dae; Kim, Sei Joon; Jeon, Mi Jin; Chok, Yoon Jin; Kim, Ki Kwang; Lee, Seul Bee

    2011-01-01

    Helical Tomotherapy allows only coplanar beam delivery because it does not allow couch rotation. We investigated a method to introduce non-coplanar beam by tilting a patient's head for Tomotherapy. The aim of this study was to compare intrafractional movement during Tomotherapy between coplanar and non-coplanar patient's setup. Helical Tomotherapy was used for treating eight patients with intracranial tumor. The subjects were divided into three groups: one group (coplanar) of 2 patients who lay on S-plate with supine position and wore thermoplastic mask for immobilizing the head, second group (non-coplanar) of 3 patients who lay on S-plate with supine position and whose head was tilted with Variable Axis Baseplate and wore thermoplastic mask, and third group (non-coplanar plus mouthpiece) of 3 patients whose head was tilted and wore a mouthpiece immobilization device and thermoplastic mask. The patients were treated with Tomotherapy after treatment planning with Tomotherapy Planning System. Megavoltage computed tomography (MVCT) was performed before and after treatment, and the intrafractional error was measured with lateral(X), longitudinal(Y), vertical(Z) direction movements and vector (√x 2 +√y 2 +√z 2 ) value for assessing overall movement. Intrafractional error was compared among three groups by taking the error of MVCT taken after the treatment. As the correction values (X, Y, Z) between MVCT image taken after treatment and CT-simulation image are close to zero, the patient movement is small. When the mean values of movement of each direction for non-coplanar setup were compared with coplanar setup group, X-axis movement was decreased by 13%, but Y-axis and Z-axis movement were increased by 109% and 88%, respectively. Movements of Y-axis and Z-axis with non-coplanar setup were relatively greater than that of X-axis since a tilted head tended to slip down. The mean of X-axis movement of the group who used a mouthpiece was greater by 9.4% than the group

  7. Dynamic intensity-modulated non-coplanar arc radiotherapy (INCA) for head and neck cancer

    International Nuclear Information System (INIS)

    Krayenbuehl, Jerome; Davis, J. Bernard; Ciernik, I. Frank

    2006-01-01

    Background and purpose: To define the potential advantages of intensity-modulated radiotherapy (IMRT) applied using a non-coplanar dynamic arc technique for the treatment of head and neck cancer. Materials and methods: External beam radiotherapy (EBRT) was planned in ten patients with head and neck cancer using coplanar IMRT and non-coplanar arc techniques, termed intensity modulated non-coplanar arc EBRT (INCA). Planning target volumes (PTV1) of first order covered the gross tumor volume and surrounding clinical target volume treated with 68-70 Gy, whereas PTV2 covered the elective lymph nodes with 54-55 Gy using a simultaneous internal boost. Treatment plan comparison between IMRT and INCA was carried out using dose-volume histogram and 'equivalent uniform dose' (EUD). Results: INCA resulted in better dose coverage and homogeneity of the PTV1, PTV2, and reduced dose delivered to most of the organs at risk (OAR). For the parotid glands, a reduction of the mean dose of 2.9 (±2.0) Gy was observed (p 0.002), the mean dose to the larynx was reduced by 6.9 (±2.9) Gy (p 0.003), the oral mucosa by 2.4 (±1.1) Gy (p < 0.001), and the maximal dose to the spinal cord by 3.2 (±1.7) Gy (p = 0.004). The mean dose to the brain was increased by 3.0 (±1.4) Gy (p = 0.002) and the mean lung dose increased by 0.2 (±0.4) Gy (p = 0.87). The EUD suggested better avoidance of the OAR, except for the lung, and better coverage and dose uniformity were achieved with INCA compared to IMRT. Conclusion: Dose delivery accuracy with IMRT using a non-coplanar dynamic arc beam geometry potentially improves treatment of head and neck cancer

  8. 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.

  9. 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.

  10. Image Reconstruction in Radio Astronomy with Non-Coplanar Synthesis Arrays

    Science.gov (United States)

    Goodrick, L.

    2015-03-01

    Traditional radio astronomy imaging techniques assume that the interferometric array is coplanar, with a small field of view, and that the two-dimensional Fourier relationship between brightness and visibility remains valid, allowing the Fast Fourier Transform to be used. In practice, to acquire more accurate data, the non-coplanar baseline effects need to be incorporated, as small height variations in the array plane introduces the w spatial frequency component. This component adds an additional phase shift to the incoming signals. There are two approaches to account for the non-coplanar baseline effects: either the full three-dimensional brightness and visibility model can be used to reconstruct an image, or the non-coplanar effects can be removed, reducing the three dimensional relationship to that of the two-dimensional one. This thesis describes and implements the w-projection and w-stacking algorithms. The aim of these algorithms is to account for the phase error introduced by non-coplanar synthesis arrays configurations, making the recovered visibilities more true to the actual brightness distribution model. This is done by reducing the 3D visibilities to a 2D visibility model. The algorithms also have the added benefit of wide-field imaging, although w-stacking supports a wider field of view at the cost of more FFT bin support. For w-projection, the w-term is accounted for in the visibility domain by convolving it out of the problem with a convolution kernel, allowing the use of the two-dimensional Fast Fourier Transform. Similarly, the w-Stacking algorithm applies a phase correction in the image domain to image layers to produce an intensity model that accounts for the non-coplanar baseline effects. This project considers the KAT7 array for simulation and analysis of the limitations and advantages of both the algorithms. Additionally, a variant of the Högbom CLEAN algorithm was used which employs contour trimming for extended source emission flagging. The

  11. 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

  12. Lung stereotactic body radiotherapy using a coplanar versus a non-coplanar beam technique: a comparison of clinical outcomes

    Science.gov (United States)

    Stauder, Michael C.; Miller, Robert C.; Garces, Yolanda I.; Foote, Robert L.; Sarkaria, Jann N.; Bauer, Heather J.; Mayo, Charles S.; Olivier, Kenneth R.

    2013-01-01

    Objectives To determine if lung stereotactic body radiotherapy (SBRT) using a coplanar beam technique was associated with similar outcomes as lung SBRT using a non-coplanar beam technique. Methods A retrospective review was performed of patients undergoing lung SBRT between January 2008 and April 2011. SBRT was initially delivered with multiple non-coplanar, non-overlapping beams; however, starting in December 2009, SBRT was delivered predominantly with all coplanar beams in order to reduce treatment time and complexity. Results This analysis included 149 patients; the median follow-up was 21 months. SBRT was delivered for primary (n = 90) or recurrent (n = 17) non-small cell lung cancer, or lung oligometastasis (n = 42). The most common dose (Gy)/fraction (fx) regimens were 48 Gy/4 fx (39%), 54 Gy/3 fx (37%), and 50 Gy/5 fx (17%). The beam arrangement was coplanar in 61 patients (41%) and non-coplanar in 88 patients (59%). In patients treated with 54 Gy/3 fx, the mean treatment times per fraction for the coplanar and non-coplanar cohorts were 10 and 14 minutes (p < 0.0001). Kaplan-Meier 2-year estimates of overall survival (OS), progression-free survival, and local control (LC) for the coplanar and non-coplanar cohorts were 65% vs. 56% (p = 0.30), 47% vs. 39% (p = 0.71), and 92% and 92% (p = 0.94), respectively. The 1-year estimates of grade 2-5 pulmonary toxicity for the coplanar and non-coplanar cohorts were 11% and 17%, respectively (p = 0.30). On multivariate analysis, beam arrangement was not significantly associated with OS, LC or pulmonary toxicity. Conclusions Patients treated with lung SBRT using a coplanar technique had similar outcomes as those treated with a non-coplanar technique. PMID:29296365

  13. TU-CD-304-05: 4Ï€ Non-Coplanar Radiotherapy: From Mathematical Modeling to Clinical Implementation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, V; Nguyen, D; Tran, A; Ruan, D; Cao, M; Kaprealian, T; Kupelian, P; Low, D; Sheng, K [Department of Radiation Oncology, UCLA, Los Angeles, CA (United States)

    2015-06-15

    Purpose: To develop and clinically implement 4π radiotherapy, an inverse optimization platform that maximally utilizes non-coplanar intensity modulated radiotherapy (IMRT) beams to significantly improve critical organ sparing. Methods: A 3D scanner was used to digitize the human and phantom subject surfaces, which were positioned in the computer assisted design (CAD) model of a TrueBeam machine to create a virtual geometrical model, based on which, the feasible beam space was calculated for different tumor locations. Beamlets were computed for all feasible beams using convolution/superposition. A column generation algorithm was employed to optimize patient specific beam orientations and fluence maps. Optimal routing through all selected beams were calculated by a level set method. The resultant plans were converted to XML files and delivered to phantoms in the TrueBeam developer mode. Finally, 4π plans were recomputed in Eclipse and manually delivered to recurrent GBM patients. Results: Compared to IMRT utilizing manually selected beams and volumetric modulated arc therapy plans, markedly improved dosimetry was observed using 4π for the brain, head and neck, liver, lung, and prostate patients. The improvements were due to significantly improved conformality and reduced high dose spillage to organs mediolateral to the PTV. The virtual geometrical model was experimentally validated. Safety margins with 99.9% confidence in collision avoidance were included to the model based model accuracy estimates determined via 300 physical machine to phantom distance measurements. Automated delivery in the developer mode was completed in 10 minutes and collision free. Manual 4 π treatment on the GBM cases resulted in significant brainstem sparing and took 35–45 minutes including multiple images, which showed submillimeter cranial intrafractional motion. Conclusion: The mathematical modeling utilized in 4π is accurate to create and guide highly complex non-coplanar IMRT

  14. SU-F-T-416: Dosimetric Comparison of Coplanar and Non-Coplanar IMRT Plans for Peripheral Lung Lesion

    International Nuclear Information System (INIS)

    Kang, J; Zhang, S; Philbrook, S; Paul, S; Wang, B

    2016-01-01

    Purpose: The purpose of this study was to compare dosimetric parameters of treatment plans between coplanar and non-coplanar techniques for treating peripheral lung lesions. Methods: The planning CT scans of 6 patients in supine positions were used in this study. The size of the PTV ranges from 163 c.c. to 782 c.c.. The locations of PTV are mostly at the peripheral of Lung, some spreading to the mediastinum. For each patient, we generated two IMRT plans, one with and the other without non-coplanar beams. The non-coplanar beams were carefully selected so that the beams would never exit patient bodies through the contralateral lung. The IMRT plans were generated with Pinnacle 9.8 treatment planning software. The IMRT optimization objectives were kept the same for the corresponding pairs of plans. All plans were normalized such that 95% of PTV receives the prescription dose (full dose). Results: The conformity index (mean±standard deviation of the mean) is 1.49±0.14 and 1.58±0.23 for the coplanar and noncoplanar plans, respectively. The heterogeneity index (mean±standard deviation of the mean) is 7.74 ±2.33 and 6.34±1.40 for the coplanar and non-coplanar plans, respectively. The maximum heart dose is 60.94±6.22 and 60.42±7.21 Gy, and mean heart dose is 10.22 ±7.57, 9.07 ±6.32 Gy, for the coplanar and non-coplanar plans, respectively. The ipsilateral lung V20 is 48.0%±2.4% and 47.5%±3.3%, and V5 is 68.2%±10.0% and 69.1%±7.3%, for the coplanar and noncoplanar plans, respectively. Furthermore, with the non-coplanar beam arrangement, the contralateral lung V20 was reduced from 3.3%±3.7% to 1.3%±0.8%, and the contralateral Lung V5 is reduced significantly from 65.6%±9.3% to 33.5%±20.9% (p value =0.008). Conclusion: The IMRT plans with non-coplanar beam arrangement could reduce the exit dose to the contralateral lung, and therefore reduce the contralateral lung V5 significantly. This method is especially helpful while the lung lesion doesn’t have a

  15. The treatment of extensive scalp lesions using coplanar and non-coplanar photon IMRT: a single institution experience

    International Nuclear Information System (INIS)

    Ostheimer, Christian; Janich, Martin; Hübsch, Patrick; Gerlach, Reinhard; Vordermark, Dirk

    2014-01-01

    This clinical study compared four different cases of extensive scalp malignancies treated by intensity-modulated radiation therapy. The merits of coplanar and non-coplanar Step-and-shoot total scalp irradiation techniques were evaluated against the background of the literature. Four patients (angiosarcoma, n=2, cutaneous B-cell non-Hodgkin lymphoma, B-NHL, n=1, mycosis fungoides, n=1) treated between 2008 and 2012 at our institution were retrospectively analyzed. For every patient with executed coplanar plan, a non-coplanar plan and vice versa has been calculated additionally for direct comparison. Three patients underwent limited surgery before radiotherapy. Individual adapted bolus material was used for every patient (helmet). Total scalp dose was 30 Gy (B-NHL, mycosis fungoides) and 50 Gy (angiosarcoma) with fractional doses of 2.0-2.5 Gy (without sequential local boost in three patients). Conformity and homogeneity indexes and dose volume histograms were used for treatment plan comparison. Dose hot spots were higher in coplanar plans (110-128% Dmax). Non-coplanar plans showed a more homogeneous dose distribution (HI = .12 - .17) and superior PTV coverage (88 - 96%). Target dose coverage was 81-117% in non-coplanar and 30-128% in coplanar plans. Coplanar plans yielded a stronger dose gradient across the target (.7-1.6 Gy/mm) compared to non-coplanar plans (.8-1.3 Gy/mm). The most conformal plan was a non-coplanar plan (CI = .7). Mean and maximum brain doses were comparable and showed an almost linear decrease between min. and max. dose. The optic chiasm and brain stem was spared most with non-coplanar plans, mean doses to the lenses ranged between 4 and 8 Gy and were higher in non-coplanar plans as were doses to the optic nerves. Radiotherapy tolerance was acceptable and acute side effects included erythema, scalp pain, alopecia and radiodermatitis which all spontaneously resolved. Two patients accomplished partial response, two patients showed complete response

  16. 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

  17. Connectivity editing for quad-dominant meshes

    KAUST Repository

    Peng, Chihan; Wonka, Peter

    2013-01-01

    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.

  18. Comparison of static conformal field with multiple noncoplanar arc techniques for stereotactic radiosurgery or stereotactic radiotherapy

    International Nuclear Information System (INIS)

    Hamilton, Russell J.; Kuchnir, Franca T.; Sweeney, Patrick; Rubin, Steven J.; Dujovny, Manuel; Pelizzari, Charles A.; Chen, George T. Y.

    1995-01-01

    Purpose: Compare the use of static conformal fields with the use of multiple noncoplanar arcs for stereotactic radiosurgery or stereotactic radiotherapy treatment of intracranial lesions. Evaluate the efficacy of these treatment techniques to deliver dose distributions comparable to those considered acceptable in current radiotherapy practice. Methods and Materials: A previously treated radiosurgery case of a patient presenting with an irregularly shaped intracranial lesion was selected. Using a three-dimensional (3D) treatment-planning system, treatment plans using a single isocenter multiple noncoplanar arc technique and multiple noncoplanar conformal static fields were generated. Isodose distributions and dose volume histograms (DVHs) were computed for each treatment plan. We required that the 80% (of maximum dose) isodose surface enclose the target volume for all treatment plans. The prescription isodose was set equal to the minimum target isodose. The DVHs were analyzed to evaluate and compare the different treatment plans. Results: The dose distribution in the target volume becomes more uniform as the number of conformal fields increases. The volume of normal tissue receiving low doses (> 10% of prescription isodose) increases as the number of static fields increases. The single isocenter multiple arc plan treats the greatest volume of normal tissue to low doses, approximately 1.6 times more volume than that treated by four static fields. The volume of normal tissue receiving high (> 90% of prescription isodose) and intermediate (> 50% of prescription isodose) doses decreases by 29 and 22%, respectively, as the number of static fields is increased from four to eight. Increasing the number of static fields to 12 only further reduces the high and intermediate dose volumes by 10 and 6%, respectively. The volume receiving the prescription dose is more than 3.5 times larger than the target volume for all treatment plans. Conclusions: Use of a multiple noncoplanar

  19. SU-F-BRB-12: A Novel Haar Wavelet Based Approach to Deliver Non-Coplanar Intensity Modulated Radiotherapy Using Sparse Orthogonal Collimators

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, D; Ruan, D; Low, D; Sheng, K [Deparment of Radiation Oncology, University of California Los Angeles, Los Angeles, CA (United States); O’Connor, D [Deparment of Mathematics, University of California Los Angeles, Los Angeles, CA (United States); Boucher, S [RadiaBeam Technologies, Santa Monica, CA (United States)

    2015-06-15

    Purpose: Existing efforts to replace complex multileaf collimator (MLC) by simple jaws for intensity modulated radiation therapy (IMRT) resulted in unacceptable compromise in plan quality and delivery efficiency. We introduce a novel fluence map segmentation method based on compressed sensing for plan delivery using a simplified sparse orthogonal collimator (SOC) on the 4π non-coplanar radiotherapy platform. Methods: 4π plans with varying prescription doses were first created by automatically selecting and optimizing 20 non-coplanar beams for 2 GBM, 2 head & neck, and 2 lung patients. To create deliverable 4π plans using SOC, which are two pairs of orthogonal collimators with 1 to 4 leaves in each collimator bank, a Haar Fluence Optimization (HFO) method was used to regulate the number of Haar wavelet coefficients while maximizing the dose fidelity to the ideal prescription. The plans were directly stratified utilizing the optimized Haar wavelet rectangular basis. A matching number of deliverable segments were stratified for the MLC-based plans. Results: Compared to the MLC-based 4π plans, the SOC-based 4π plans increased the average PTV dose homogeneity from 0.811 to 0.913. PTV D98 and D99 were improved by 3.53% and 5.60% of the corresponding prescription doses. The average mean and maximal OAR doses slightly increased by 0.57% and 2.57% of the prescription doses. The average number of segments ranged between 5 and 30 per beam. The collimator travel time to create the segments decreased with increasing leaf numbers in the SOC. The two and four leaf designs were 1.71 and 1.93 times more efficient, on average, than the single leaf design. Conclusion: The innovative dose domain optimization based on compressed sensing enables uncompromised 4π non-coplanar IMRT dose delivery using simple rectangular segments that are deliverable using a sparse orthogonal collimator, which only requires 8 to 16 leaves yet is unlimited in modulation resolution. This work is

  20. An Experimental and Numerical Study on Cracking Behavior of Brittle Sandstone Containing Two Non-coplanar Fissures Under Uniaxial Compression

    Science.gov (United States)

    Yang, Sheng-Qi; Tian, Wen-Ling; Huang, Yan-Hua; Ranjith, P. G.; Ju, Yang

    2016-04-01

    To understand the fracture mechanism in all kinds of rock engineering, it is important to investigate the fracture evolution behavior of pre-fissured rock. In this research, we conducted uniaxial compression experiments to evaluate the influence of ligament angle on the strength, deformability, and fracture coalescence behavior of rectangular prismatic specimens (80 × 160 × 30 mm) of brittle sandstone containing two non-coplanar fissures. The experimental results show that the peak strength of sandstone containing two non-coplanar fissures depends on the ligament angle, but the elastic modulus is not closely related to the ligament angle. With the increase of ligament angle, the peak strength decreased at a ligament angle of 60°, before increasing up to our maximum ligament angle of 120°. Crack initiation, propagation, and coalescence were all observed and characterized from the inner and outer tips of pre-existing non-coplanar fissures using photographic monitoring. Based on the results, the sequence of crack evolution in sandstone containing two non-coplanar fissures was analyzed in detail. In order to fully understand the crack evolution mechanism of brittle sandstone, numerical simulations using PFC2D were performed for specimens containing two non-coplanar fissures under uniaxial compression. The results are in good agreement with the experimental results. By analyzing the stress field, the crack evolution mechanism in brittle sandstone containing two non-coplanar fissures under uniaxial compression is revealed. These experimental and numerical results are expected to improve the understanding of the unstable fracture mechanism of fissured rock engineering structures.

  1. 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 ...

  2. 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...

  3. Adaptive Mesh Refinement in CTH

    International Nuclear Information System (INIS)

    Crawford, David

    1999-01-01

    This paper reports progress on implementing a new capability of adaptive mesh refinement into the Eulerian multimaterial shock- physics code CTH. The adaptivity is block-based with refinement and unrefinement occurring in an isotropic 2:1 manner. The code is designed to run on serial, multiprocessor and massive parallel platforms. An approximate factor of three in memory and performance improvements over comparable resolution non-adaptive calculations has-been demonstrated for a number of problems

  4. Selection of coplanar or noncoplanar beams using three-dimensional optimization based on maximum beam separation and minimized nontarget irradiation

    International Nuclear Information System (INIS)

    Das, Shiva K.; Marks, Lawrence B.

    1997-01-01

    Purpose: The design of an appropriate set of multiple fixed fields to achieve a steep dose gradient at the tumor edge, with minimal normal tissue exposure, is a very difficult problem, since a virtually infinite number of possible beam orientations exists. In practice we have selected beams in an iterative and often time-consuming process. This work proposes an optimization method, based on geometric and dose elements, to effectively arrive at a set of beam orientations. Methods and Materials: Beams are selected by minimizing a goal function including an angle function (beam separation for steep dose gradient at target edge) and a length function (related to normal tissue dose volume histogram). The relative importance of these two factors may be adjusted depending on the clinic situation. The model is flexible and can include case specific practical anatomic and physical considerations. Results: In extremely simple situations, the goal function yields results consistent with well-known analytical solutions. When applied to more complex clinical situations, it provides clinically reasonable solutions similar to those empirically developed by the clinician. The optimization process takes approximately 25 min on a UNIX workstation. Conclusion: The optimization scheme provides a practical means for rapidly designing multiple field coplanar or noncoplanar treatments. It overcomes limitations in human three-dimensional visualization such as trying to visualize beam directions and keeping track of the hinge angle between beams while accounting for anatomic/machine constraints. In practice, it has been used as a starting point for physicians to make modifications, based on their clinical judgment

  5. Double exchange model on triangular lattice: Non-coplanar spin configuration and phase transition near quarter filling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G.P., E-mail: bugubird_zhang@hotmail.com [Department of Physics, Renmin University of China, Beijing 100872 (China); Zhang, Jian [3M Company, 3M Corporate Headquarters, 3M Center, St. Paul, MN 55144-1000 (United States); Zhang, Qi-Li [Data Center for High Energy Density Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Zhou, Jiang-Tao [College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Shangguan, M.H. [Department of Physics, Renmin University of China, Beijing 100872 (China)

    2013-05-15

    Unconventional anomalous Hall effect in frustrated pyrochlore oxides is originated from spin chirality of non-coplanar localized spins, which can also be induced by the competition between ferromagnetic (FM) double exchange interaction J{sub H} and antiferromagnetic superexchange interaction J{sub AF}. Here truncated polynomial expansion method and Monte Carlo simulation are adopted to investigate the above model on two-dimensional triangular lattice. We discuss the influence of the range of FM-type spin–spin correlation and strong electron–spin correlation on the truncation error of spin–spin correlation near quarter filling. Two peaks of the probability distribution of spin–spin correlation in non-coplanar spin configuration clearly show that non-coplanar spin configuration is an intermediate phase between FM and 120° spin phase. Near quarter filling, there is a phase transition from FM into non-coplanar and further into 120° spin phase when J{sub AF} continually increases. Finally the effect of temperature on the magnetic structure is discussed.

  6. Evaluation of optical data gained by ARAMIS-measurement of abdominal wall movements for an anisotropic pattern design of stress-adapted hernia meshes produced by embroidery technology

    Science.gov (United States)

    Breier, A.; Bittrich, L.; Hahn, J.; Spickenheuer, A.

    2017-10-01

    For the sustainable repair of abdominal wall hernia the application of hernia meshes is required. One reason for the relapse of hernia after surgery is seen in an inadequate adaption of the mechanical properties of the mesh to the movements of the abdominal wall. Differences in the stiffness of the mesh and the abdominal tissue cause tension, friction and stress resulting in a deficient tissue response and subsequently in a recurrence of a hernia, preferentially in the marginal area of the mesh. Embroidery technology enables a targeted influence on the mechanical properties of the generated textile structure by a directed thread deposition. Textile parameters like stitch density, alignment and angle can be changed easily and locally in the embroidery pattern to generate a space-resolved mesh with mechanical properties adapted to the requirement of the surrounding tissue. To determine those requirements the movements of the abdominal wall and the resulting distortions need to be known. This study was conducted to gain optical data of the abdominal wall movements by non-invasive ARAMIS-measurement on 39 test persons to estimate direction and value of the major strains.

  7. 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

  8. 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.

  9. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang

    2011-12-12

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

  10. 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.

  11. Factorized distorted wave approximation for the (e,2e) reaction on atoms : noncoplanar symmetric

    International Nuclear Information System (INIS)

    Dixon, A.J.; McCarthy, I.E.; Noble, C.J.; Weigold, E.

    1977-02-01

    Angular and energy correlations for electrons produced in the ionization of neon and xenon by electrons with energies between 400eV and 2.5 keV have been measured using symmetric noncoplanar kinematics. The reaction yields information about the atomic orbitals and their correlations when analysed with the distorted-wave off-shell impulse approximation. In the past either plane waves or various eikonal approximations have been used for the distorted waves, and in the cases where the eikonal parameters are approximately related to the elastic scattering the spectroscopic sum rule has been approximately verified. In the present work calculations have also been carried out using partial-wave-expanded optical model wave functions which describe the elastic scattering in detail. (Author)

  12. A scheme of measurement of quantum-vacuum geometric phases in a noncoplanar fibre system

    International Nuclear Information System (INIS)

    Shen Jianqi

    2004-01-01

    We study the quantum-vacuum geometric phases resulting from the vacuum fluctuation of photon fields in a Tomita-Chiao-Wu noncoplanar curved fibre system, and suggest a scheme to test for the potential existence of such a vacuum effect. Since the signs of the quantum-vacuum geometric phases of left- and right-handed (LRH) circularly polarized light are opposite, the sum of the geometric phases at the vacuum level is necessarily zero in the fibre experiments performed previously by other authors. By using the present approach where a fibre made of gyroelectric media is employed, the quantum-vacuum geometric phases of LRH light cannot be exactly cancelled, and it may therefore be possible to test this experimentally. (letter to the editor)

  13. SU-E-T-436: Fluence-Based Trajectory Optimization for Non-Coplanar VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, G; Bamber, JC; Bedford, JL [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom); Evans, PM [Centre for Vision, Speech and Signal Processing, University of Surrey, Guildford (United Kingdom); Saran, FH; Mandeville, HC [The Royal Marsden NHS Foundation Trust, Sutton (United Kingdom)

    2015-06-15

    Purpose: To investigate a fluence-based trajectory optimization technique for non-coplanar VMAT for brain cancer. Methods: Single-arc non-coplanar VMAT trajectories were determined using a heuristic technique for five patients. Organ at risk (OAR) volume intersected during raytracing was minimized for two cases: absolute volume and the sum of relative volumes weighted by OAR importance. These trajectories and coplanar VMAT formed starting points for the fluence-based optimization method. Iterative least squares optimization was performed on control points 24° apart in gantry rotation. Optimization minimized the root-mean-square (RMS) deviation of PTV dose from the prescription (relative importance 100), maximum dose to the brainstem (10), optic chiasm (5), globes (5) and optic nerves (5), plus mean dose to the lenses (5), hippocampi (3), temporal lobes (2), cochleae (1) and brain excluding other regions of interest (1). Control point couch rotations were varied in steps of up to 10° and accepted if the cost function improved. Final treatment plans were optimized with the same objectives in an in-house planning system and evaluated using a composite metric - the sum of optimization metrics weighted by importance. Results: The composite metric decreased with fluence-based optimization in 14 of the 15 plans. In the remaining case its overall value, and the PTV and OAR components, were unchanged but the balance of OAR sparing differed. PTV RMS deviation was improved in 13 cases and unchanged in two. The OAR component was reduced in 13 plans. In one case the OAR component increased but the composite metric decreased - a 4 Gy increase in OAR metrics was balanced by a reduction in PTV RMS deviation from 2.8% to 2.6%. Conclusion: Fluence-based trajectory optimization improved plan quality as defined by the composite metric. While dose differences were case specific, fluence-based optimization improved both PTV and OAR dosimetry in 80% of cases.

  14. Radiation dose in critical organs due to non-coplanar irradiation of the pituitary gland

    International Nuclear Information System (INIS)

    Schulte, R.W.M.; Rittmann, K.L.; Meinass, H.J.; Rennicke, P.

    1996-01-01

    In order to estimate the somatic and genetic risk associated with a non-coplanar linac-based radiation technique of the pituitary gland, systematic secondary-dose measurements in a phantom and sample measurements of the dose near critical organs of patients were performed. For measurements of the dose outside the primary radiation field an acrylic-PVC phantom was used which was irradiated with a single field (4x4 cm 2 ). Eight patients with pituitary tumors were treated isocentrically with a combination of sagittal and transverse rotational arcs. To measure the dose in critical organs, LiF thermoluminescence dosimeters (TLD) in chip form were placed onto 1 eyelid, the skin over the thyroid, and the patient's clothes covering the region of breasts and ovaries of female patients and the testicles of male patients. Measurements were performed for all patients during 1 sagittal irradiation and for the majority of patients during 1 transverse irradiation. The phantom measurements demonstrated that the secondary dose measured on the patients surface can be considered as a good approximation for the dose in adjacent organs. The median dose in critical organs for sagittal irradiation was in the range of 25.8 mGy (eyes) to 1.9 mGy (testicles), and for transverse irradiation in the range of 23.3 mGy (eyes) to 1.3 mGy (testicles). The ratio of median organ doses for sagittal and transverse irradiation was 2.1 for the thyroid gland, 1.1 for the eyes, and 1.5 for the other organs. The dose in critical organs due to non-coplanar irradiation of the pituitary gland is only a small fraction of the dose delivered to the reference point of the planning target volume. The risk of a radiation-induced tumor and a genetic consequence associated with these small doses is generally less than 1% and 0.1%, respectively. (orig./MG) [de

  15. Design of village power and micro-grids for rural areas of Zimbabwe with specific attention to voltage regulation on low voltage meshed distribution grids

    Energy Technology Data Exchange (ETDEWEB)

    Tinarwo, David

    2009-07-01

    This work constitutes a feasibility study of the use of renewable energy resources in rural farming villages in Zimbabwe. A case study was done for a farming village consisting of a dairy farm called Rosenwald with 627 dairy cows and surrounded by local villagers offering manpower labour for the dairy activities. The village setup presents great opportunities for a sustainable power supply system in the form of village power system using the powerful microgrid concept since the farm is already connected to the national grid but with great problems of reliability, which is already a national problem if not regional due to the worst economics crisis facing the country coupled with the present regional power shortage experiencing the whole Southern Africa region. With the intended on-farm energy generation, the energy services are to be extended to the surrounding villages. Thus the study aims to stimulate better focus to the use of locally available renewable energy resources at bigger scales starting from the disadvantaged communities in the rural areas. The focus is put to these rural farming communities because these could be a strong force in the speedy electrification of the poor communities surrounding them. This could be more viable given the already existing business activities in these farms. So in this thesis the study of the on-farm energy generation using the farm and animal waste has shown that such communities can be totally independent from the electric grid by using the locally available resources. Here the technologies assessed are the biogas and solar and all the evaluation of the designs, choice of components and their suitable sizes was done with the help of a micropower optimization model HOMER simulation programme from National Renewable Energy Laboratory available at their website www.nrel.gov/homer. From the assessment done for the case study farm, it was shown that an electricity price of EUR 0.26/kWh is possible from the on - farm energy

  16. 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.

  17. 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

  18. 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.

  19. Advantages and disadvantages of using non-coplanar techniques in radiotherapy of the abdomen formed 3D

    International Nuclear Information System (INIS)

    Urena Llinares, A.; Castro Ramirez, I.; Iborra Oquendo, M. A; Quinones Rodriguez, L. A.; Angulo Pain, E.

    2011-01-01

    3D Radiotherapy locations abdomen, especially in pancreas and stomach cancers is often extremely difficult if we are to meet the dose constraints to organs at risk due to proximity and many of these (liver, kidneys, intestines, lungs, bone. ..). Of these, the most critical are the kidneys, which also present values of tolerance, in most cases difficult to meet. This is done in our hospital are using non-coplanar techniques performing well both as coating PTV dose to both kidneys.

  20. SU-F-T-649: Dosimetric Evaluation of Non-Coplanar Arc Therapy Using a Novel Rotating Gamma Ray System

    Energy Technology Data Exchange (ETDEWEB)

    Eldib, A; Chibani, O; Jin, L; Fan, J; Veltchev, I; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Mora, G [Universidade de Lisboa, Codex, Lisboa (Portugal); Li, J [Cyber Medical Inc, Xian, Shaanxi (China)

    2016-06-15

    Purpose: Stereotactic intra and extra-cranial body radiation therapy has evolved with advances in treatment accuracy, effective radiation dose, and parameters necessary to maximize machine capabilities. Novel gamma systems with a ring type gantry were developed having the ability to perform oblique arcs. The aim of this study is to explore the dosimetric advantages of this new system. Methods: The rotating Gamma system is named CybeRay (Cyber Medical Corp., Xian, China). It has a treatment head of 16 cobalt-60 sources focused to the isocenter, which can rotate 360° on the ring gantry and swing 35° in the superior direction. Treatment plans were generated utilizing our in-house Monte Carlo treatment planning system. A cylindrical phantom was modeled with 2mm voxel size. Dose inside the cylindrical phantom was calculated for coplanar and non-coplanar arcs. Dosimetric differences between CybeRay cobalt beams and CyberKnife 6MV beams were compared in a lung phantom and for previously treated SBRT patients. Results: The full width at half maxima of cross profiles in the S-I direction for the coplanar setup matched the cone sizes, while for the non-coplanar setup, FWHM was larger by 2mm for a 10mm cone and about 5mm for larger cones. In the coronal and sagittal view, coplanar beams showed elliptical shaped isodose lines, while non-coplanar beams showed circular isodose lines. Thus proper selection of the oblique angle and cone size can aid optimal dose matching to the target volume. Comparing a single 5mm cone from CybeRay to that from CyberKnife showed similar penumbra in a lung phantom but CybeRay had significant lower doses beyond lung tissues. Comparable treatment plans were obtained with CybeRay as that from CyberKnife.ConclusionThe noncoplanar multiple source arrangement of CybeRay will be of great clinical benefits for stereotactic intra and extra-cranial radiation therapy.

  1. Fraction-variant beam orientation optimization for non-coplanar IMRT

    Science.gov (United States)

    O'Connor, Daniel; Yu, Victoria; Nguyen, Dan; Ruan, Dan; Sheng, Ke

    2018-02-01

    Conventional beam orientation optimization (BOO) algorithms for IMRT assume that the same set of beam angles is used for all treatment fractions. In this paper we present a BOO formulation based on group sparsity that simultaneously optimizes non-coplanar beam angles for all fractions, yielding a fraction-variant (FV) treatment plan. Beam angles are selected by solving a multi-fraction fluence map optimization problem involving 500-700 candidate beams per fraction, with an additional group sparsity term that encourages most candidate beams to be inactive. The optimization problem is solved using the fast iterative shrinkage-thresholding algorithm. Our FV BOO algorithm is used to create five-fraction treatment plans for digital phantom, prostate, and lung cases as well as a 30-fraction plan for a head and neck case. A homogeneous PTV dose coverage is maintained in all fractions. The treatment plans are compared with fraction-invariant plans that use a fixed set of beam angles for all fractions. The FV plans reduced OAR mean dose and D 2 values on average by 3.3% and 3.8% of the prescription dose, respectively. Notably, mean OAR dose was reduced by 14.3% of prescription dose (rectum), 11.6% (penile bulb), 10.7% (seminal vesicle), 5.5% (right femur), 3.5% (bladder), 4.0% (normal left lung), 15.5% (cochleas), and 5.2% (chiasm). D 2 was reduced by 14.9% of prescription dose (right femur), 8.2% (penile bulb), 12.7% (proximal bronchus), 4.1% (normal left lung), 15.2% (cochleas), 10.1% (orbits), 9.1% (chiasm), 8.7% (brainstem), and 7.1% (parotids). Meanwhile, PTV homogeneity defined as D 95/D 5 improved from .92 to .95 (digital phantom), from .95 to .98 (prostate case), and from .94 to .97 (lung case), and remained constant for the head and neck case. Moreover, the FV plans are dosimetrically similar to conventional plans that use twice as many beams per fraction. Thus, FV BOO offers the potential to reduce delivery time for non-coplanar IMRT.

  2. Noncoplanar Stereotactic Body Radiation Therapy for Centrally Located or Larger Lung Tumors

    International Nuclear Information System (INIS)

    Dong, Peng; Lee, Percy; Ruan, Dan; Long, Troy; Romeijn, Edwin; Low, Daniel A.; Kupelian, Patrick; Abraham, John; Yang, Yingli; Sheng, Ke

    2013-01-01

    Purpose: To investigate the dosimetric improvements in stereotactic body radiation therapy for patients with larger or central lung tumors using a highly noncoplanar 4π planning system. Methods and Materials: This study involved 12 patients with centrally located or larger lung tumors previously treated with 7- to 9-field static beam intensity modulated radiation therapy to 50 Gy. They were replanned using volumetric modulated arc therapy and 4π plans, in which a column generation method was used to optimize the beam orientation and the fluence map. Maximum doses to the heart, esophagus, trachea/bronchus, and spinal cord, as well as the 50% isodose volume, the lung volumes receiving 20, 10, and 5 Gy were minimized and compared against the clinical plans. A dose escalation study was performed to determine whether a higher prescription dose to the tumor would be achievable using 4π without violating dose limits set by the clinical plans. The deliverability of 4π plans was preliminarily tested. Results: Using 4π plans, the maximum heart, esophagus, trachea, bronchus and spinal cord doses were reduced by 32%, 72%, 37%, 44%, and 53% (P≤.001), respectively, and R 50 was reduced by more than 50%. Lung V 20 , V 10 , and V 5 were reduced by 64%, 53%, and 32% (P≤.001), respectively. The improved sparing of organs at risk was achieved while also improving planning target volume (PTV) coverage. The minimal PTV doses were increased by the 4π plans by 12% (P=.002). Consequently, escalated PTV doses of 68 to 70 Gy were achieved in all patients. Conclusions: We have shown that there is a large potential for plan quality improvement and dose escalation for patients with larger or centrally located lung tumors using noncoplanar beams with sufficient quality and quantity. Compared against the clinical volumetric modulated arc therapy and static intensity modulated radiation therapy plans, the 4π plans yielded significantly and consistently improved tumor coverage and

  3. Noncoplanar Stereotactic Body Radiation Therapy for Centrally Located or Larger Lung Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Peng; Lee, Percy; Ruan, Dan [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California (United States); Long, Troy; Romeijn, Edwin [Department of Industrial and Operations Engineering, University of Michigan, Ann Arbor, Michigan (United States); Low, Daniel A.; Kupelian, Patrick; Abraham, John; Yang, Yingli [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California (United States); Sheng, Ke, E-mail: ksheng@mednet.ucla.edu [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California (United States)

    2013-07-01

    Purpose: To investigate the dosimetric improvements in stereotactic body radiation therapy for patients with larger or central lung tumors using a highly noncoplanar 4π planning system. Methods and Materials: This study involved 12 patients with centrally located or larger lung tumors previously treated with 7- to 9-field static beam intensity modulated radiation therapy to 50 Gy. They were replanned using volumetric modulated arc therapy and 4π plans, in which a column generation method was used to optimize the beam orientation and the fluence map. Maximum doses to the heart, esophagus, trachea/bronchus, and spinal cord, as well as the 50% isodose volume, the lung volumes receiving 20, 10, and 5 Gy were minimized and compared against the clinical plans. A dose escalation study was performed to determine whether a higher prescription dose to the tumor would be achievable using 4π without violating dose limits set by the clinical plans. The deliverability of 4π plans was preliminarily tested. Results: Using 4π plans, the maximum heart, esophagus, trachea, bronchus and spinal cord doses were reduced by 32%, 72%, 37%, 44%, and 53% (P≤.001), respectively, and R{sub 50} was reduced by more than 50%. Lung V{sub 20}, V{sub 10}, and V{sub 5} were reduced by 64%, 53%, and 32% (P≤.001), respectively. The improved sparing of organs at risk was achieved while also improving planning target volume (PTV) coverage. The minimal PTV doses were increased by the 4π plans by 12% (P=.002). Consequently, escalated PTV doses of 68 to 70 Gy were achieved in all patients. Conclusions: We have shown that there is a large potential for plan quality improvement and dose escalation for patients with larger or centrally located lung tumors using noncoplanar beams with sufficient quality and quantity. Compared against the clinical volumetric modulated arc therapy and static intensity modulated radiation therapy plans, the 4π plans yielded significantly and consistently improved tumor

  4. SU-F-BRB-04: Comparison of Coplanar VMAT, Non-Coplanar VMAT, and 4π Treatment Plans

    International Nuclear Information System (INIS)

    Woods, K; Nguyen, D; Tran, A; Yu, V; Cao, M; Sheng, K

    2015-01-01

    Purpose: The 4π non-coplanar radiotherapy delivery technique has demonstrated significantly better normal tissue sparing and dose conformality than the clinically used volumetric modulated arc therapy (VMAT). It is unclear whether this is a fundamental limitation of VMAT delivery or the coplanar nature of its typical clinical plans. The non-coplanar basis of 4π is incorporated into VMAT treatment planning to compare its effect on plan quality. Methods: Clinical stereotactic body radiation therapy plans for 9 liver patients treated with 30–60 Gy using coplanar VMAT (cVMAT) were re-planned using non-coplanar VMAT (nVMAT) with 3 arcs and 4 π with 20 intensity-modulated non-coplanar fields. All plans were optimized to deliver 100% of the prescribed dose to 95% of the planning target volume (PTV), and nVMAT and 4π plans were tailored to match the maximum and mean PTV dose from the clinical plan. The conformality index (CI), 50% dose spillage volume (R50), normal liver volume receiving >15 Gy (VL>15), and doses to organs at risk (OARs) were compared for all three treatment plans. Results: Compared to cVMAT, the nVMAT and 4π plans reduced VL>15 by an average of 30.6 cm3 and 96.3 cm3, respectively. The average CI was also reduced from 1.22 (cVMAT) to 1.17 (nVMAT) and 1.14 (4π), indicating higher conformality in the same order. Similarly, R50 was reduced from 3.87 (cVMAT) to 3.58 (nVMAT) and 2.74 (4π). With the exception of the mean right kidney dose, which increased by an average of only 0.6 Gy for nVMAT, the dose differences to OARs were not statistically significant between the two VMAT plans. 4π plans either significantly decreased or maintained OAR doses. Conclusion: While the manual selection of intuitive non-coplanar arcs does show some improvement over coplanar VMAT, the automated beam selection for 4π still results in superior plan quality. This project is supported in part by Varian Medical Systems and NIH R43 CA183390

  5. Design with Nonlinear Constraints

    KAUST Repository

    Tang, Chengcheng

    2015-01-01

    . The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application

  6. The Clinical Value of Non-Coplanar Photon Beams in Biologically Optimized Intensity Modulated Dose Delivery on Deep-Seated Tumours

    International Nuclear Information System (INIS)

    Ferreira, Brigida C.; Svensson, Roger; Loef, Johan; Brahme, Anders

    2003-01-01

    The aim of the present study is to compare the merits of different radiobiologically optimized treatment techniques using few-field planar and non-coplanar dose delivery on an advanced cancer of the cervix, with rectum and bladder as principal organs at risk. Classically, the rational for using non-coplanar beams is to minimize the overlap of beam entrance and exit regions and to find new beam directions avoiding organs at risk, in order to reduce damage to sensitive normal tissues. Two four-beam configurations have been extensively studied. The first consists of three evenly spaced coplanar beams and a fourth non-coplanar beam. A second tetrahedral-like configuration, with two symmetric non-coplanar beams at the same gantry angle and two coplanar beams, with optimized beam directions, was also tested. The present study shows that when radiobiologically optimized intensity modulated beams are applied to such a geometry, only a marginal increase in the treatment outcome can be achieved by non-coplanar beams compared to the optimal coplanar treatment. The main reason for this result is that the high dose in the beam-overlap regions is already optimally reduced by biologically optimized intensity modulation in the plane. The large number of degrees of freedom already incorporated in the treatment by the use of intensity modulation and radiobiological optimization, leads to the saturation of the benefit acquired by a further increase in the degrees of freedom with non-coplanar beams. In conclusion, the use coplanar of radiobiologically optimized intensity modulation simplifies the dose delivery, reducing the need for non-coplanar beam portals

  7. 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)

  8. 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.

  9. 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.

  10. 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.

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

    Science.gov (United States)

    Liu, Zheng; Xue, Kaiping; Hong, Peilin

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

  12. 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.

  13. 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

  14. Beam’s-eye-view imaging during non-coplanar lung SBRT

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Stephen S. F., E-mail: syip@lroc.harvard.edu; Rottmann, Joerg; Berbeco, Ross I. [Department of Radiation Oncology, Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2015-12-15

    Purpose: Beam’s-eye-view (BEV) imaging with an electronic portal imaging device (EPID) can be performed during lung stereotactic body radiation therapy (SBRT) to monitor the tumor location in real-time. Image quality for each patient and treatment field depends on several factors including the patient anatomy and the gantry and couch angles. The authors investigated the angular dependence of automatic tumor localization during non-coplanar lung SBRT delivery. Methods: All images were acquired at a frame rate of 12 Hz with an amorphous silicon EPID. A previously validated markerless lung tumor localization algorithm was employed with manual localization as the reference. From ten SBRT patients, 12 987 image frames of 123 image sequences acquired at 48 different gantry–couch rotations were analyzed. δ was defined by the position difference of the automatic and manual localization. Results: Regardless of the couch angle, the best tracking performance was found in image sequences with a gantry angle within 20° of 250° (δ = 1.40 mm). Image sequences acquired with gantry angles of 150°, 210°, and 350° also led to good tracking performances with δ = 1.77–2.00 mm. Overall, the couch angle was not correlated with the tracking results. Among all the gantry–couch combinations, image sequences acquired at (θ = 30°, ϕ = 330°), (θ = 210°, ϕ = 10°), and (θ = 250°, ϕ = 30°) led to the best tracking results with δ = 1.19–1.82 mm. The worst performing combinations were (θ = 90° and 230°, ϕ = 10°) and (θ = 270°, ϕ = 30°) with δ > 3.5 mm. However, 35% (17/48) of the gantry–couch rotations demonstrated substantial variability in tracking performances between patients. For example, the field angle (θ = 70°, ϕ = 10°) was acquired for five patients. While the tracking errors were ≤1.98 mm for three patients, poor performance was found for the other two patients with δ ≥ 2.18 mm, leading to average tracking error of 2.70 mm. Only one

  15. Noncoplanar magnetic fields at collisionless shocks: A test of a new approach

    International Nuclear Information System (INIS)

    Gosling, J.T.; Winske, D.; Thomsen, M.F.

    1988-01-01

    Within the foot and ramp of a fast mode collisionless shock the magnetic field rotates out of the plane of coplanarity defined by the upstream magnetic field and the shock normal. As previously noted (Goodrich and Scudder, 1984), the sense of this rotation is such as to reduce the cross-shock potential drop when measured in the deHoffman-Teller frame relative to that measured in the normal incidence frame. From a consideration of the requirement that there be zero current in the coplanarity plane downstream of the shock, Jones and Ellison (1987) have argued that the field rotation and potential drop difference are a consequence of unequal ion and electron masses, and have derived an expression for the spatial integral of the noncoplanar field component in terms of the electron current within the shock layer. Moreover, by assuming that the ion current within the shock layer is negligible compared to the electron current, they derive equations which predict the magnitude of both the field rotation and the potential drop difference in terms of upstream quantities and the field jump at the shock. We have tested their equations with ISEE 1 and 2 plasma and field measurements at the Earth's bow shock and by means of numerical simulations. We find substantial support for their suggestion that the field rotation and thus also the frame dependence of the potential drop are fundamentally a consequence of unequal ion and electron masses. Further, for subcritical shocks (low Mach number) one can neglect the ion current to predict both the sign and the magnitude of the field rotation and potential drop difference. However, at supercritical shocks (high Mach numbers) the ion current associated with reflected, gyrating ions cannot be neglected, and the final equations of Jones and Ellison seriously underestimate the magnitude of the field rotation and the potential drop difference at these shocks

  16. Constrained customization of non-coplanar beam orientations in radiotherapy of brain tumours

    International Nuclear Information System (INIS)

    Rowbottom, C.G.; Oldham, M.; Webb, S.

    1999-01-01

    A methodology for the constrained customization of non-coplanar beam orientations in radiotherapy treatment planning has been developed and tested on a cohort of five patients with tumours of the brain. The methodology employed a combination of single and multibeam cost functions to produce customized beam orientations. The single-beam cost function was used to reduce the search space for the multibeam cost function, which was minimized using a fast simulated annealing algorithm. The scheme aims to produce well-spaced, customized beam orientations for each patient that produce low dose to organs at risk (OARs). The customized plans were compared with standard plans containing the number and orientation of beams chosen by a human planner. The beam orientation constraint-customized plans employed the same number of treatment beams as the standard plan but with beam orientations chosen by the constrained-customization scheme. Improvements from beam orientation constraint-customization were studied in isolation by customizing the beam weights of both plans using a dose-based downhill simplex algorithm. The results show that beam orientation constraint-customization reduced the maximum dose to the orbits by an average of 18.8 (±3.8, 1SD)% and to the optic nerves by 11.4 (±4.8, 1SD)% with no degradation of the planning target volume (PTV) dose distribution. The mean doses, averaged over the patient cohort, were reduced by 4.2 (±1.1, 1SD)% and 12.4 (±3.1 1SD)% for the orbits and optic nerves respectively. In conclusion, the beam orientation constraint-customization can reduce the dose to OARs, for few-beam treatment plans, when compared with standard treatment plans developed by a human planner. (author)

  17. Adaptive mesh refinement in titanium

    Energy Technology Data Exchange (ETDEWEB)

    Colella, Phillip; Wen, Tong

    2005-01-21

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

  18. Short-term outcomes of the transvaginal minimal mesh procedure for pelvic organ prolapse

    OpenAIRE

    Naoko Takazawa; Akiko Fujisaki; Yasukuni Yoshimura; Akira Tsujimura; Shigeo Horie

    2018-01-01

    Purpose: This study aimed to evaluate the clinical outcomes and complications of transvaginal minimal mesh repair without using commercially available kits for treatment of pelvic organ prolapse (POP). Materials and Methods: This retrospective cohort study involved 91 women who underwent surgical management of POP with originally designed small mesh between July 2014 and August 2015. This mesh is 56% smaller than the mesh widely used in Japan, and it has only two arms delivered into each righ...

  19. 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.

  20. 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.

  1. 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.

  2. Beam angle selection for intensity-modulated radiotherapy (IMRT) treatment of unresectable pancreatic cancer: are noncoplanar beam angles necessary?

    Science.gov (United States)

    Chang, D S; Bartlett, G K; Das, I J; Cardenes, H R

    2013-09-01

    External beam radiation therapy with concurrent chemotherapy (CRT) is widely used for the treatment of unresectable pancreatic cancer. Noncoplanar (NCP) 3D conformal radiotherapy (3DCRT) and coplanar (CP) IMRT have been reported to lower the radiation dose to organs at risk (OARs). The purpose of this article is to examine the utility of noncoplanar beam angles in IMRT for the management of pancreatic cancer. Sixteen patients who were treated with CRT for unresectable adenocarcinoma of the pancreatic head or neck were re-planned using CP and NCP beams in 3DCRT and IMRT with the Varian Eclipse treatment planning system. Compared to CP IMRT, NCP IMRT had similar target coverage with slightly increased maximum point dose, 5,799 versus 5,775 cGy (p = 0.008). NCP IMRT resulted in lower mean kidney dose, 787 versus 1,210 cGy (p kidney dose, but did not improve other dose-volume criteria. The use of NCP beam angles is preferred only in patients with risk factors for treatment-related kidney dysfunction.

  3. Expected Transmission Energy Route Metric for Wireless Mesh Senor Networks

    Directory of Open Access Journals (Sweden)

    YanLiang Jin

    2011-01-01

    Full Text Available Mesh is a network topology that achieves high throughput and stable intercommunication. With great potential, it is expected to be the key architecture of future networks. Wireless sensor networks are an active research area with numerous workshops and conferences arranged each year. The overall performance of a WSN highly depends on the energy consumption of the network. This paper designs a new routing metric for wireless mesh sensor networks. Results from simulation experiments reveal that the new metric algorithm improves the energy balance of the whole network and extends the lifetime of wireless mesh sensor networks (WMSNs.

  4. 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.

  5. 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

  6. Non-coplanar volumetric-modulated arc therapy (VMAT) for craniopharyngiomas reduces radiation doses to the bilateral hippocampus: a planning study comparing dynamic conformal arc therapy, coplanar VMAT, and non-coplanar VMAT

    International Nuclear Information System (INIS)

    Uto, Megumi; Mizowaki, Takashi; Ogura, Kengo; Hiraoka, Masahiro

    2016-01-01

    Recent studies suggest that radiation-induced injuries to the hippocampus play important roles in compromising neurocognitive functioning for patients with brain tumors and it could be important to spare the hippocampus using modern planning methods for patients with craniopharyngiomas. As bilateral hippocampus are located on the same level as the planning target volume (PTV) in patients with craniopharyngioma, it seems possible to reduce doses to hippocampus using non-coplanar beams. While the use of non-coplanar beams in volumetric-modulated arc therapy (VMAT) of malignant intracranial tumors has recently been reported, no dosimetric comparison has yet been made between VMAT using non-coplanar arcs (ncVMAT) and VMAT employing only coplanar arcs (coVMAT) among patients with craniopharyngiomas. We performed a planning study comparing dose distributions to the PTV, hippocampus, and other organs at risk (OAR) of dynamic conformal arc therapy (DCAT), coVMAT, and ncVMAT. DCAT, coVMAT, and ncVMAT plans were created for 10 patients with craniopharyngiomas. The prescription dose was 52.2 Gy in 29 fractions, and 99 % of each PTV was covered by 90 % of the prescribed dose. The maximum dose was held below 107 % of the prescribed dose. CoVMAT and ncVMAT plans were formulated to satisfy the following criteria: the doses to the hippocampus were minimized, and the doses to the OAR were similar to or lower than those of DCAT. The mean equivalent doses in 2-Gy fractions to 40 % of the volumes of the bilateral hippocampus [EQD 2 (40% hippos )] were 15.4/10.8/6.5 Gy for DCAT/coVMAT/ncVMAT, respectively. The EQD 2 (40% hippos ) for ncVMAT were <7.3 Gy, which is the threshold predicting cognitive impairment, as defined by Gondi et al.. The mean doses to normal brain tissue and the conformity indices were similar for the three plans, and the homogeneity indices were significantly better for coVMAT and ncVMAT compared with DCAT. NcVMAT is more appropriate than DCAT and coVMAT for

  7. 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

  8. 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.

  9. 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...

  10. 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...

  11. 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.

  12. 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.

  13. 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 ...

  14. Prosthetic Mesh Repair for Incarcerated Inguinal Hernia

    Directory of Open Access Journals (Sweden)

    Cihad Tatar

    2016-08-01

    Full Text Available Background: Incarcerated inguinal hernia is a commonly encountered urgent surgical condition, and tension-free repair is a well-established method for the treatment of noncomplicated cases. However, due to the risk of prosthetic material-related infections, the use of mesh in the repair of strangulated or incarcerated hernia has often been subject to debate. Recent studies have demonstrated that biomaterials represent suitable materials for performing urgent hernia repair. Certain studies recommend mesh repair only for cases where no bowel resection is required; other studies, however, recommend mesh repair for patients requiring bowel resection as well. Aim: The aim of this study was to compare the outcomes of different surgical techniques performed for strangulated hernia, and to evaluate the effect of mesh use on postoperative complications. Study Design: Retrospective cross-sectional study. Methods: This retrospective study was performed with 151 patients who had been admitted to our hospital’s emergency department to undergo surgery for a diagnosis of incarcerated inguinal hernia. The patients were divided into two groups based on the applied surgical technique. Group 1 consisted of 112 patients treated with mesh-based repair techniques, while Group 2 consisted of 39 patients treated with tissue repair techniques. Patients in Group 1 were further divided into two sub-groups: one consisting of patients undergoing bowel resection (Group 3, and the other consisting of patients not undergoing bowel resection (Group 4. Results: In Group 1, it was observed that eight (7.14% of the patients had wound infections, while two (1.78% had hematomas, four (3.57% had seromas, and one (0.89% had relapse. In Group 2, one (2.56% of the patients had a wound infection, while three (7.69% had hematomas, one (2.56% had seroma, and none had relapses. There were no statistically significant differences between the two groups with respect to wound infection

  15. SU-F-T-352: Development of a Knowledge Based Automatic Lung IMRT Planning Algorithm with Non-Coplanar Beams

    International Nuclear Information System (INIS)

    Zhu, W; Wu, Q; Yuan, L

    2016-01-01

    Purpose: To improve the robustness of a knowledge based automatic lung IMRT planning method and to further validate the reliability of this algorithm by utilizing for the planning of clinical cases with non-coplanar beams. Methods: A lung IMRT planning method which automatically determines both plan optimization objectives and beam configurations with non-coplanar beams has been reported previously. A beam efficiency index map is constructed to guide beam angle selection in this algorithm. This index takes into account both the dose contributions from individual beams and the combined effect of multiple beams which is represented by a beam separation score. We studied the effect of this beam separation score on plan quality and determined the optimal weight for this score.14 clinical plans were re-planned with the knowledge-based algorithm. Significant dosimetric metrics for the PTV and OARs in the automatic plans are compared with those in the clinical plans by the two-sample t-test. In addition, a composite dosimetric quality index was defined to obtain the relationship between the plan quality and the beam separation score. Results: On average, we observed more than 15% reduction on conformity index and homogeneity index for PTV and V_4_0, V_6_0 for heart while an 8% and 3% increase on V_5, V_2_0 for lungs, respectively. The variation curve of the composite index as a function of angle spread score shows that 0.6 is the best value for the weight of the beam separation score. Conclusion: Optimal value for beam angle spread score in automatic lung IMRT planning is obtained. With this value, model can result in statistically the “best” achievable plans. This method can potentially improve the quality and planning efficiency for IMRT plans with no-coplanar angles.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. User Manual for the PROTEUS Mesh Tools

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-01

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

  1. User Manual for the PROTEUS Mesh Tools

    International Nuclear Information System (INIS)

    Smith, Micheal A.; Shemon, Emily R.

    2015-01-01

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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.).

  7. Adaptive Meshing for Bi-directional Information Flows

    DEFF Research Database (Denmark)

    Nicholas, Paul; Zwierzycki, Mateusz; Stasiuk, David

    2016-01-01

    This paper describes a mesh-based modelling approach that supports the multiscale design of a panelised, thin-skinned metal structure. The term multi-scale refers to the decomposition of a design modelling problem into distinct but interdependent models associated with particular scales, and the ...

  8. A Generic Mesh Data Structure with Parallel Applications

    Science.gov (United States)

    Cochran, William Kenneth, Jr.

    2009-01-01

    High performance, massively-parallel multi-physics simulations are built on efficient mesh data structures. Most data structures are designed from the bottom up, focusing on the implementation of linear algebra routines. In this thesis, we explore a top-down approach to design, evaluating the various needs of many aspects of simulation, not just…

  9. Performance of FACTS equipment in Meshed systems

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

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

  10. Design of nano- and microfiber combined scaffolds by electrospinning of collagen onto starch-based fiber meshes: a man-made equivalent of natural extracellular matrix.

    Science.gov (United States)

    Tuzlakoglu, Kadriye; Santos, Marina I; Neves, Nuno; Reis, Rui L

    2011-02-01

    Mimicking the structural organization and biologic function of natural extracellular matrix has been one of the main goals of tissue engineering. Nevertheless, the majority of scaffolding materials for bone regeneration highlights biochemical functionality in detriment of mechanical properties. In this work we present a rather innovative construct that combines in the same structure electrospun type I collagen nanofibers with starch-based microfibers. These combined structures were obtained by a two-step methodology and structurally consist in a type I collagen nano-network incorporated on a macro starch-based support. The morphology of the developed structures was assessed by several microscopy techniques and the collagenous nature of the nano-network was confirmed by immunohistochemistry. In addition, and especially regarding the requirements of large bone defects, we also successfully introduced the concept of layer by layer, as a way to produce thicker structures. In an attempt to recreate bone microenvironment, the design and biochemical composition of the combined structures also envisioned bone-forming cells and endothelial cells (ECs). The inclusion of a type I collagen nano-network induced a stretched morphology and improved the metabolic activity of osteoblasts. Regarding ECs, the presence of type I collagen on the combined structures provided adhesive support and obviated the need of precoating with fibronectin. It was also importantly observed that ECs on the nano-network organized into circular structures, a three-dimensional arrangement distinct from that observed for osteoblasts and resembling the microcappillary-like organizations formed during angiogenesis. By providing simultaneously physical and chemical cues for cells, the herein-proposed combined structures hold a great potential in bone regeneration as a man-made equivalent of extracellular matrix.

  11. Mechanical behaviour of synthetic surgical meshes: finite element simulation of the herniated abdominal wall.

    Science.gov (United States)

    Hernández-Gascón, B; Peña, E; Melero, H; Pascual, G; Doblaré, M; Ginebra, M P; Bellón, J M; Calvo, B

    2011-11-01

    The material properties of meshes used in hernia surgery contribute to the overall mechanical behaviour of the repaired abdominal wall. The mechanical response of a surgical mesh has to be defined since the haphazard orientation of an anisotropic mesh can lead to inconsistent surgical outcomes. This study was designed to characterize the mechanical behaviour of three surgical meshes (Surgipro®, Optilene® and Infinit®) and to describe a mechanical constitutive law that accurately reproduces the experimental results. Finally, through finite element simulation, the behaviour of the abdominal wall was modelled before and after surgical mesh implant. Uniaxial loading of mesh samples in two perpendicular directions revealed the isotropic response of Surgipro® and the anisotropic behaviour of Optilene® and Infinit®. A phenomenological constitutive law was used to reproduce the measured experimental curves. To analyze the mechanical effect of the meshes once implanted in the abdomen, finite element simulation of the healthy and partially herniated repaired rabbit abdominal wall served to reproduce wall behaviour before and after mesh implant. In all cases, maximal displacements were lower and maximal principal stresses higher in the implanted abdomen than the intact wall model. Despite the fact that no mesh showed a behaviour that perfectly matched that of abdominal muscle, the Infinit® mesh was able to best comply with the biomechanics of the abdominal wall. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Intensity-Modulated Radiation Therapy with Noncoplanar Beams for Treatment of Prostate Cancer in Patients with Bilateral Hip Prosthesis-A Case Study

    International Nuclear Information System (INIS)

    Brooks, Chris; Cheung, Rex Min; Kudchadker, Rajat J.

    2010-01-01

    Megavoltage photon intensity-modulated radiation therapy (IMRT) is typically used in the treatment of prostate cancer at our institution. Approximately 1% to 2% of patients with prostate cancer have hip prostheses. The presence of the prosthesis usually complicates the planning process because of dose perturbation around the prosthesis, radiation attenuation through the prosthesis, and the introduction of computed tomography artifacts in the planning volume. In addition, hip prostheses are typically made of materials of high atomic number, which add uncertainty to the dosimetry of the prostate and critical organs in the planning volume. When the prosthesis is bilateral, treatment planning is further complicated because only a limited number of beam angles can be used to avoid the prostheses. In this case study, we will report the observed advantages of using noncoplanar beams in the delivery of IMRT to a prostate cancer patient with bilateral hip prostheses. The treatment was planned for 75.6 Gy using a 7-field coplanar approach and a noncoplanar arrangement, with all fields avoiding entrance though the prostheses. Our results indicate that, compared with the coplanar plan, the noncoplanar plan delivers the prescribed dose to the target with a slightly better conformality and sparing of rectal tissue versus the coplanar plan.

  13. Multigrid for refined triangle meshes

    Energy Technology Data Exchange (ETDEWEB)

    Shapira, Yair

    1997-02-01

    A two-level preconditioning method for the solution of (locally) refined finite element schemes using triangle meshes is introduced. In the isotropic SPD case, it is shown that the condition number of the preconditioned stiffness matrix is bounded uniformly for all sufficiently regular triangulations. This is also verified numerically for an isotropic diffusion problem with highly discontinuous coefficients.

  14. A SURVEY on WIRELESS MESH NETWORKS, ROUTING METRICS and PROTOCOLS

    Directory of Open Access Journals (Sweden)

    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.

  15. 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....

  16. 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 ...

  17. Management of complications of mesh surgery.

    Science.gov (United States)

    Lee, Dominic; Zimmern, Philippe E

    2015-07-01

    Transvaginal placements of synthetic mid-urethral slings and vaginal meshes have largely superseded traditional tissue repairs in the current era because of presumed efficacy and ease of implant with device 'kits'. The use of synthetic material has generated novel complications including mesh extrusion, pelvic and vaginal pain and mesh contraction. In this review, our aim is to discuss the management, surgical techniques and outcomes associated with mesh removal. Recent publications have seen an increase in presentation of these mesh-related complications, and reports from multiple tertiary centers have suggested that not all patients benefit from surgical intervention. Although the true incidence of mesh complications is unknown, recent publications can serve to guide physicians and inform patients of the surgical outcomes from mesh-related complications. In addition, the literature highlights the growing need for a registry to account for a more accurate reporting of these events and to counsel patients on the risk and benefits before proceeding with mesh surgeries.

  18. TH-EF-BRB-03: Significant Cord and Esophagus Dose Reduction by 4π Non-Coplanar Spine Stereotactic Body Radiation Therapy and Stereotactic Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Yu, V; Tran, A; Nguyen, D; Woods, K; Cao, M; Kaprealian, T; Chin, R; Low, D; Sheng, K [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To demonstrate significant organ-at-risk (OAR) sparing achievable with 4π non-coplanar radiotherapy on spine SBRT and SRS patients. Methods: Twenty-five stereotactic spine cases previously treated with VMAT (n = 23) or IMRT (n = 2) were included in this study. A computer-aided-design model of a Linac with a 3D-scanned human surface was utilized to determine the feasible beam space throughout the 4π steradian and beam specific source-to-target-distances (STD) required for collision avoidance. 4π radiotherapy plans integrating beam orientation and fluence map optimization were then created using a column-generation algorithm. Twenty optimal beams were selected for each case. To evaluate the tradeoff between dosimetric benefit and treatment complexity, 4π plans including only isocentrically deliverable beams were also created. Beam angles of all standard and isocentric 4π plans were imported into Eclipse to recalculate the dose using the same calculation engine as the clinical plans for unbiased comparison. OAR and PTV dose statistics for the clinical, standard-4π, and isocentric-4π plans were compared. Results: Comparing standard-4π to clinical plans, particularly significant average percent reduction in the [mean, maximum] dose of the cord and esophagus of [41%, 21.7%], and [38.7%, 36.4%] was observed, along with global decrease in all other OAR dose statistics. The average cord volume receiving more than 50% prescription dose was substantially decreased by 76%. In addition, improved PTV coverage was demonstrated with a maximum dose reduction of 0.93% and 1.66% increase in homogeneity index (D95/D5). All isocentric-4π plans achieved dosimetric performance equivalent to that of the standard-4π plans with higher delivery complexity. Conclusion: 4π radiotherapy significantly improves stereotactic spine treatment dosimetry. With the substantial OAR dose sparing, PTV dose escalation is considerably safer. Isocentric-4π is sufficient to achieve the

  19. 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

  20. 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.

  1. 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.

  2. 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..

  3. Parallel Block Structured Adaptive Mesh Refinement on Graphics Processing Units

    Energy Technology Data Exchange (ETDEWEB)

    Beckingsale, D. A. [Atomic Weapons Establishment (AWE), Aldermaston (United Kingdom); Gaudin, W. P. [Atomic Weapons Establishment (AWE), Aldermaston (United Kingdom); Hornung, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gunney, B. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gamblin, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Herdman, J. A. [Atomic Weapons Establishment (AWE), Aldermaston (United Kingdom); Jarvis, S. A. [Atomic Weapons Establishment (AWE), Aldermaston (United Kingdom)

    2014-11-17

    Block-structured adaptive mesh refinement is a technique that can be used when solving partial differential equations to reduce the number of zones necessary to achieve the required accuracy in areas of interest. These areas (shock fronts, material interfaces, etc.) are recursively covered with finer mesh patches that are grouped into a hierarchy of refinement levels. Despite the potential for large savings in computational requirements and memory usage without a corresponding reduction in accuracy, AMR adds overhead in managing the mesh hierarchy, adding complex communication and data movement requirements to a simulation. In this paper, we describe the design and implementation of a native GPU-based AMR library, including: the classes used to manage data on a mesh patch, the routines used for transferring data between GPUs on different nodes, and the data-parallel operators developed to coarsen and refine mesh data. We validate the performance and accuracy of our implementation using three test problems and two architectures: an eight-node cluster, and over four thousand nodes of Oak Ridge National Laboratory’s Titan supercomputer. Our GPU-based AMR hydrodynamics code performs up to 4.87× faster than the CPU-based implementation, and has been scaled to over four thousand GPUs using a combination of MPI and CUDA.

  4. 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.

  5. Shuffle-Exchange Mesh Topology for Networks-on-Chip

    OpenAIRE

    Sabbaghi-Nadooshan, Reza; Modarressi, Mehdi; Sarbazi-Azad, Hamid

    2010-01-01

    The mesh topology has been used in a variety of interconnection network applications especially for NoC designs due to its desirable properties in VLSI implementation. In this chapter, we proposed a new topology based on the shuffle-exchange topology, the 2D

  6. 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.

  7. 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.

  8. 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.

  9. Non-coplanar polychlorinated biphenyls (PCBs) are direct agonists for the human pregnane-X receptor and constitutive androstane receptor, and activate target gene expression in a tissue-specific manner

    International Nuclear Information System (INIS)

    Al-Salman, Fadheela; Plant, Nick

    2012-01-01

    The polychlorinated biphenyl group possesses high environmental persistence, leading to bioaccumulation and a number of adverse effects in mammals. Whilst coplanar PCBs elicit their toxic effects through agonism of the aryl hydrocarbon receptor; however, non-coplanar PCBs are not ligands for AhR, but may be ligands for members of the nuclear receptor family of proteins. To better understand the biological actions of non-coplanar PCBs, we have undertaken a systematic analysis of their ability to activate PXR and CAR-mediated effects. Cells were exposed to a range of non-coplanar PCBs (99, 138, 153, 180 and 194), or the coplanar PCB77: Direct activation of PXR and CAR was measured using a mammalian receptor activation assay in human liver cells, with rifampicin and CITCO used as positive controls ligands for PXR and CAR, respectively; activation of target gene expression was examined using reporter gene plasmids for CYP3A4 and MDR1 transfected into liver, intestine and lung cell lines. Several of the non-coplanar PCBs directly activated PXR and CAR, whilst the coplanar PCB77 did not. Non-coplanar PCBs were also able to activate PXR/CAR target gene expression in a substitution- and tissue-specific manner. Non-coplanar PCBs act as direct activators for the nuclear receptors PXR and CAR, and are able to elicit transcriptional activation of target genes in a substitution- and tissue-dependent manner. Chronic activation of PXR/CAR is linked to adverse effects and must be included in any risk assessment of PCBs. -- Highlights: ► Several Non-coplanar PCBs are able to directly activate both PXR and CAR in vitro. ► PCB153 is the most potent direct activator of PXR and CAR nuclear receptors. ► Non-coplanar PCB activation of CYP3A4/MDR1 reporter genes is structure-dependent. ► Non-coplanar PCB activate CYP3A4/MDR1 reporter genes in a tissue-dependent. ► PCB153 is the most potent activator of PXR/CAR target gene in all tissues.

  10. Basic Algorithms for the Asynchronous Reconfigurable Mesh

    Directory of Open Access Journals (Sweden)

    Yosi Ben-Asher

    2002-01-01

    Full Text Available Many constant time algorithms for various problems have been developed for the reconfigurable mesh (RM in the past decade. All these algorithms are designed to work with synchronous execution, with no regard for the fact that large size RMs will probably be asynchronous. A similar observation about the PRAM model motivated many researchers to develop algorithms and complexity measures for the asynchronous PRAM (APRAM. In this work, we show how to define the asynchronous reconfigurable mesh (ARM and how to measure the complexity of asynchronous algorithms executed on it. We show that connecting all processors in a row of an n×n ARM (the analog of barrier synchronization in the APRAM model can be solved with complexity Θ(nlog⁡n. Intuitively, this is average work time for solving such a problem. Next, we describe general a technique for simulating T -step synchronous RM algorithms on the ARM with complexity of Θ(T⋅n2log⁡n. Finally, we consider the simulation of the classical synchronous algorithm for counting the number of non-zero bits in an n bits vector using (k

  11. Conkiss: Conformal Kidneys Sparing 3D Noncoplanar Radiotherapy Treatment for Pancreatic Cancer As an Alternative to IMRT

    International Nuclear Information System (INIS)

    Sebestyen, Zsolt; Kovacs, Peter; Gulyban, Akos; Farkas, Robert; Bellyei, Szabolcs; Liposits, Gabor; Szigeti, Andras; Esik, Olga; Derczy, Katalin; Mangel, Laszlo

    2011-01-01

    When treating pancreatic cancer using standard (ST) 3D conformal radiotherapy (3D-CRT) beam arrangements, the kidneys often receive a higher dose than their probable tolerance limit. Our aim was to elaborate a new planning method that-similarly to IMRT-effectively spares the kidneys without compromising the target coverage. Conformal kidneys sparing (CONKISS) 5-field, noncoplanar plans were compared with ST plans for 23 consecutive patients retrospectively. Optimal beam arrangements were used consisting of a left- and right-wedged beam-pair and an anteroposterior beam inclined in the caudal direction. The wedge direction determination (WEDDE) algorithm was developed to adjust the adequate direction of wedges. The aimed organs at risk (OARs) mean dose limits were: kidney <12 Gy, liver <25 Gy, small bowels <30 Gy, and spinal cord maximum <45 Gy. Conformity and homogeneity indexes with z-test were used to evaluate and compare the different planning approaches. The mean dose to the kidneys decreased significantly (p < 0.05): left kidney 7.7 vs. 10.7 Gy, right kidney 9.1 vs. 11.7 Gy. Meanwhile the mean dose to the liver increased significantly (18.1 vs. 15.0 Gy). The changes in the conformity, homogeneity, and in the doses to other OARs were not significant. The CONKISS method balances the load among the OARs and significantly reduces the dose to the kidneys, without any significant change in the conformity and homogeneity. Using 3D-CRT the CONKISS method can be a smart alternative to IMRT to enhance the possibility of dose escalation.

  12. 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

  13. 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.

  14. Cone beam CT imaging with limited angle of projections and prior knowledge for volumetric verification of non-coplanar beam radiation therapy: a proof of concept study

    Science.gov (United States)

    Meng, Bowen; Xing, Lei; Han, Bin; Koong, Albert; Chang, Daniel; Cheng, Jason; Li, Ruijiang

    2013-11-01

    Non-coplanar beams are important for treatment of both cranial and noncranial tumors. Treatment verification of such beams with couch rotation/kicks, however, is challenging, particularly for the application of cone beam CT (CBCT). In this situation, only limited and unconventional imaging angles are feasible to avoid collision between the gantry, couch, patient, and on-board imaging system. The purpose of this work is to develop a CBCT verification strategy for patients undergoing non-coplanar radiation therapy. We propose an image reconstruction scheme that integrates a prior image constrained compressed sensing (PICCS) technique with image registration. Planning CT or CBCT acquired at the neutral position is rotated and translated according to the nominal couch rotation/translation to serve as the initial prior image. Here, the nominal couch movement is chosen to have a rotational error of 5° and translational error of 8 mm from the ground truth in one or more axes or directions. The proposed reconstruction scheme alternates between two major steps. First, an image is reconstructed using the PICCS technique implemented with total-variation minimization and simultaneous algebraic reconstruction. Second, the rotational/translational setup errors are corrected and the prior image is updated by applying rigid image registration between the reconstructed image and the previous prior image. The PICCS algorithm and rigid image registration are alternated iteratively until the registration results fall below a predetermined threshold. The proposed reconstruction algorithm is evaluated with an anthropomorphic digital phantom and physical head phantom. The proposed algorithm provides useful volumetric images for patient setup using projections with an angular range as small as 60°. It reduced the translational setup errors from 8 mm to generally <1 mm and the rotational setup errors from 5° to <1°. Compared with the PICCS algorithm alone, the integration of rigid

  15. 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

  16. Critical Under-Reporting of Hernia Mesh Properties and Development of a Novel Package Label.

    Science.gov (United States)

    Kahan, Lindsey G; Blatnik, Jeffrey A

    2018-02-01

    With an array of hernia meshes with varying properties, intraoperative decision making for the optimal mesh is critical. Although meshes are subjected to regulatory review through the Food and Drug Administration, it is unknown whether mesh properties are visually accessible. To facilitate greater knowledge for the surgeon on mesh choice, we aimed to comprehensively analyze hernia mesh packaging and regulations. Labeling guidelines and 510(k) requirements across Food and Drug Administration-regulated products were analyzed and compared with mesh packaging. Packages and Instructions for Use were analyzed for commonly available hernia meshes. Literature review was conducted to understand recommended guidelines for mesh products. A novel hernia mesh packaging label was designed to rectify under-reporting. We found that food labels undergo critical scrutiny and detailed specifications, yet medical devices are not subjected to similar guidelines. The highest reported property on packages was the presence of a barrier (80%), and the lowest reported property was barrier composition (33%). For Instructions for Use, the lowest reported properties were mechanics (31%) and thickness (11%), both of which were not reported on packaging. Descriptive terms for pore size and mechanics were reported inconsistently. To overcome this under-reporting of properties, we propose a novel packaging label with properties chosen from regulatory guidelines, packaging analysis, and literature review. Although standardized terminology has been proposed in literature, property knowledge has not adequately permeated surgery, industry, or regulatory guidelines. There is extreme under-reporting and lack of consistency of clinically important mesh properties. Standardized packaging labels will provide accessibility of these properties and aim to bring standardized terminology into practice. With an increase in access to important properties, this can facilitate intraoperative decision making on a

  17. 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.

  18. Dynamic channel assignment scheme for multi-radio wireless mesh networks

    CSIR Research Space (South Africa)

    Kareem, TR

    2008-09-01

    Full Text Available This paper investigates the challenges involve in designing a dynamic channel assignment (DCA) scheme for wireless mesh networks, particularly for multi-radio systems. It motivates the need for fast switching and process coordination modules...

  19. Metal-Mesh Optical Filter Technology for Mid IR, Far IR, and Submillimeter, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovative, high transmission band-pass filter technology proposed here is an improvement in multilayer metal-mesh filter design and manufacture for the far IR...

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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)

  5. 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

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

    Science.gov (United States)

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

    2017-08-01

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

  7. 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

  8. 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.

  9. Limits of dose escalation in lung cancer: a dose-volume histogram analysis comparing coplanar and non-coplanar techniques

    Energy Technology Data Exchange (ETDEWEB)

    Derycke, S; Van Duyse, B; Schelfhout, J; De Neve, W

    1995-12-01

    To evaluate the feasibility of dose escalation in radiotherapy of inoperable lung cancer, a dose-volume histogram analysis was performed comparing standard coplanar (2D) with non-coplanar (3D) beam arrangements on a non-selected group of 20 patients planned by Sherouse`s GRATISTM 3D-planning system. Serial CT-scanning was performed and 2 Target Volumes (Tvs) were defined. Gross Tumor Volume (GTV) defined a high-dose Target Volume (TV-1). GTV plus location of node stations with > 10% probability of invasion (Minet et al.) defined an intermediate-dose Target Volume (TV-2). However, nodal regions which are incompatible with cure were excluded from TV-2. These are ATS-regions 1, 8, 9 and 14 all left and right as well as heterolateral regions. For 3D-planning, Beam`s Eye View selected (by an experienced planner) beam arrangements were optimised using Superdot, a method of target dose-gradient annihilation developed by Sherouse. A second 3D-planning was performed using 4 beam incidences with maximal angular separation. The linac`s isocenter for the optimal arrangement was located at the geometrical center of gravity of a tetraheder, the tetraheder`s comers being the consecutive positions of the virtual source. This ideal beam arrangement was approximated as close as possible, taking into account technical limitations (patient-couch-gantry collisions). Criteria for tolerance were met if no points inside the spinal cord exceeded 50 Gy and if at least 50% of the lung volume received less than 20Gy. If dose regions below 50 Gy were judged acceptable at TV-2, 2D- as well as 3D-plans allow safe escalation to 80 Gy at TV-1. When TV-2 needed to be encompassed by isodose surfaces exceeding 50Gy, 3D-plans were necessary to limit dose at the spinal cord below tolerance. For large TVs dose is limited by lung tolerance for 3D-plans. An analysis (including NTCP-TCP as cost functions) of rival 3D-plans is being performed.

  10. Plan Quality and Treatment Efficiency for Radiosurgery to Multiple Brain Metastases: Non-Coplanar RapidArc vs Gamma Knife

    Directory of Open Access Journals (Sweden)

    Haisong eLiu

    2016-02-01

    Full Text Available Objectives: This study compares the dosimetry and efficiency of two modern radiosurgery (SRS modalities for multiple brain metastases (Gamma Knife and LINAC-based RapidArc/volumetric modulated arc therapy, with a special focus on the comparison of low dose spread.Methods: Six patients with three or four small brain metastases were used in this study. The size of targets varied from 0.1 ~ 10.5 cc. SRS doses were prescribed according to size of lesions. SRS plans were made using both Gamma Knife® Perfexion and a single-isocenter, multiple non-coplanar RapidArc®. Dosimetric parameters analyzed included RTOG conformity index (CI, gradient index (GI, 12 Gy isodose volume (V12Gy for each target, and the dose spread (Dspread for each plan. Dspread reflects SRS plan’s capability of confining radiation to within the local vicinity of the lesion and to not spread out to the surrounding normal brain tissues. Each plan has a dose (Dspread, such that once dose decreases below Dspread (on total tissue DVH, isodose volume starts increasing dramatically. Dspread is defined as that dose when volume increase first exceeds 20 cc per 0.1 Gy dose decrease. Results: RapidArc SRS has smaller CI (1.19 ±0.14 vs. 1.50 ± 0.16, p<0.001 and larger GI (4.77 ± 1.49 vs. 3.65 ± 0.98, p <0.01. V12Gy results were comparable (2.73 ± 1.38 cc vs. 3.06 ± 2.20 cc, p = 0.58. Moderate to lower dose spread, V6, V4.5, and V3, were also equivalent. Gamma Knife plans achieved better very low dose spread (≤3 Gy and also had slightly smaller Dspread, 1.9 Gy vs 2.5 Gy. Total treatment time for Gamma Knife is estimated between 60~100 min. Gamma Knife treatments are between 3~5 times longer compared to RapidArc treatment techniques.Conclusion: Dosimetric parameters reflecting prescription dose conformality (CI, dose fall off (GI, radiation necrosis indicator (V12Gy, and dose spread (Dspread were compared between Gamma Knife SRS and RapidArc SRS for multi-mets. RapidArc plans have

  11. Loft: An Automated Mesh Generator for Stiffened Shell Aerospace Vehicles

    Science.gov (United States)

    Eldred, Lloyd B.

    2011-01-01

    Loft is an automated mesh generation code that is designed for aerospace vehicle structures. From user input, Loft generates meshes for wings, noses, tanks, fuselage sections, thrust structures, and so on. As a mesh is generated, each element is assigned properties to mark the part of the vehicle with which it is associated. This property assignment is an extremely powerful feature that enables detailed analysis tasks, such as load application and structural sizing. This report is presented in two parts. The first part is an overview of the code and its applications. The modeling approach that was used to create the finite element meshes is described. Several applications of the code are demonstrated, including a Next Generation Launch Technology (NGLT) wing-sizing study, a lunar lander stage study, a launch vehicle shroud shape study, and a two-stage-to-orbit (TSTO) orbiter. Part two of the report is the program user manual. The manual includes in-depth tutorials and a complete command reference.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 7th International Meshing Roundtable '98

    Energy Technology Data Exchange (ETDEWEB)

    Eldred, T.J.

    1998-10-01

    The goal of the 7th International Meshing Roundtable is to bring together researchers and developers from industry, academia, and government labs in a stimulating, open environment for the exchange of technical information related to the meshing process. In the past, the Roundtable has enjoyed significant participation from each of these groups from a wide variety of countries.

  17. 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.

  18. 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...

  19. 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)

  20. 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.)

  1. 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)

  2. Surface micromachined counter-meshing gears discrimination device

    Science.gov (United States)

    Polosky, Marc A.; Garcia, Ernest J.; Allen, James J.

    2000-12-12

    A surface micromachined Counter-Meshing Gears (CMG) discrimination device which functions as a mechanically coded lock. Each of two CMG has a first portion of its perimeter devoted to continuous driving teeth that mesh with respective pinion gears. Each EMG also has a second portion of its perimeter devoted to regularly spaced discrimination gear teeth that extend outwardly on at least one of three levels of the CMG. The discrimination gear teeth are designed so as to pass each other without interference only if the correct sequence of partial rotations of the CMG occurs in response to a coded series of rotations from the pinion gears. A 24 bit code is normally input to unlock the device. Once unlocked, the device provides a path for an energy or information signal to pass through the device. The device is designed to immediately lock up if any portion of the 24 bit code is incorrect.

  3. Laser patterned carbon–polyethylene mesh electrodes for wound diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Phair, Jolene; Joshi, Mayank; Benson, John; McDonald, Damian; Davis, James, E-mail: james.davis@ulster.ac.uk

    2014-02-14

    Carbon loaded polyethylene films were selected as the base substrate for a mechanically flexible and conductive sensing material for use wound monitoring technologies. The films were processed using laser ablation of the surface to increase the effective surface area of the electrode and then subject to an oxidative electrochemical etch to improve the electron transfer kinetics. The surface morphology of the resulting films was analysed and the electrode performance in relation to monitoring uric acid, a key wound biomarker, was optimized. A prototype smart bandage was designed, based on interfacing the mesh to a portable potentiostat, and the response to urate and potential interferences assessed. - Highlights: • Innovative use of a carbon–polyethylene mesh for wound sensing applications. • Electroanalytical characterisation of a mechanically flexible conductive film. • Design and preliminary characterisation of an integrated smart bandage.

  4. Laser patterned carbon–polyethylene mesh electrodes for wound diagnostics

    International Nuclear Information System (INIS)

    Phair, Jolene; Joshi, Mayank; Benson, John; McDonald, Damian; Davis, James

    2014-01-01

    Carbon loaded polyethylene films were selected as the base substrate for a mechanically flexible and conductive sensing material for use wound monitoring technologies. The films were processed using laser ablation of the surface to increase the effective surface area of the electrode and then subject to an oxidative electrochemical etch to improve the electron transfer kinetics. The surface morphology of the resulting films was analysed and the electrode performance in relation to monitoring uric acid, a key wound biomarker, was optimized. A prototype smart bandage was designed, based on interfacing the mesh to a portable potentiostat, and the response to urate and potential interferences assessed. - Highlights: • Innovative use of a carbon–polyethylene mesh for wound sensing applications. • Electroanalytical characterisation of a mechanically flexible conductive film. • Design and preliminary characterisation of an integrated smart bandage

  5. 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.

  6. Indications, Contraindications, and Complications of Mesh in Surgical Treatment of Pelvic Organ Prolapse

    Science.gov (United States)

    Ellington, David R.; Richter, Holly E.

    2013-01-01

    Women are seeking care for pelvic organ prolapse (POP) in increasing numbers and a significant proportion of them will undergo a second repair for recurrence. This has initiated interest by both surgeons and industry to utilize and design prosthetic mesh materials to help augment longevity of prolapse repairs. Unfortunately, the introduction of transvaginal synthetic mesh kits for use in women was done without the benefit of Level 1 data to determine its utility compared to native tissue repair. This report summarizes the potential benefit/risks of transvaginal synthetic mesh use for POP and recommendations regarding its continued use. PMID:23563869

  7. [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.

  8. SU-D-BRB-01: A Comparison of Learning Methods for Knowledge Based Dose Prediction for Coplanar and Non-Coplanar Liver Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Tran, A; Ruan, D; Woods, K; Yu, V; Nguyen, D; Sheng, K [UCLA School of Medicine, Los Angeles, CA (United States)

    2016-06-15

    Purpose: The predictive power of knowledge based planning (KBP) has considerable potential in the development of automated treatment planning. Here, we examine the predictive capabilities and accuracy of previously reported KBP methods, as well as an artificial neural networks (ANN) method. Furthermore, we compare the predictive accuracy of these methods on coplanar volumetric-modulated arc therapy (VMAT) and non-coplanar 4π radiotherapy. Methods: 30 liver SBRT patients previously treated using coplanar VMAT were selected for this study. The patients were re-planned using 4π radiotherapy, which involves 20 optimally selected non-coplanar IMRT fields. ANNs were used to incorporate enhanced geometric information including liver and PTV size, prescription dose, patient girth, and proximity to beams. The performance of ANN was compared to three methods from statistical voxel dose learning (SVDL), wherein the doses of voxels sharing the same distance to the PTV are approximated by either taking the median of the distribution, non-parametric fitting, or skew-normal fitting. These three methods were shown to be capable of predicting DVH, but only median approximation can predict 3D dose. Prediction methods were tested using leave-one-out cross-validation tests and evaluated using residual sum of squares (RSS) for DVH and 3D dose predictions. Results: DVH prediction using non-parametric fitting had the lowest average RSS with 0.1176(4π) and 0.1633(VMAT), compared to 0.4879(4π) and 1.8744(VMAT) RSS for ANN. 3D dose prediction with median approximation had lower RSS with 12.02(4π) and 29.22(VMAT), compared to 27.95(4π) and 130.9(VMAT) for ANN. Conclusion: Paradoxically, although the ANNs included geometric features in addition to the distances to the PTV, it did not perform better in predicting DVH or 3D dose compared to simpler, faster methods based on the distances alone. The study further confirms that the prediction of 4π non-coplanar plans were more accurate than

  9. TH-EF-BRB-05: 4pi Non-Coplanar IMRT Beam Angle Selection by Convex Optimization with Group Sparsity Penalty

    International Nuclear Information System (INIS)

    O’Connor, D; Nguyen, D; Voronenko, Y; Yin, W; Sheng, K

    2016-01-01

    Purpose: Integrated beam orientation and fluence map optimization is expected to be the foundation of robust automated planning but existing heuristic methods do not promise global optimality. We aim to develop a new method for beam angle selection in 4π non-coplanar IMRT systems based on solving (globally) a single convex optimization problem, and to demonstrate the effectiveness of the method by comparison with a state of the art column generation method for 4π beam angle selection. Methods: The beam angle selection problem is formulated as a large scale convex fluence map optimization problem with an additional group sparsity term that encourages most candidate beams to be inactive. The optimization problem is solved using an accelerated first-order method, the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). The beam angle selection and fluence map optimization algorithm is used to create non-coplanar 4π treatment plans for several cases (including head and neck, lung, and prostate cases) and the resulting treatment plans are compared with 4π treatment plans created using the column generation algorithm. Results: In our experiments the treatment plans created using the group sparsity method meet or exceed the dosimetric quality of plans created using the column generation algorithm, which was shown superior to clinical plans. Moreover, the group sparsity approach converges in about 3 minutes in these cases, as compared with runtimes of a few hours for the column generation method. Conclusion: This work demonstrates the first non-greedy approach to non-coplanar beam angle selection, based on convex optimization, for 4π IMRT systems. The method given here improves both treatment plan quality and runtime as compared with a state of the art column generation algorithm. When the group sparsity term is set to zero, we obtain an excellent method for fluence map optimization, useful when beam angles have already been selected. NIH R43CA183390, NIH R01CA

  10. 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.

  11. 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

  12. 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.

  13. Indications, Contraindications, and Complications of Mesh in Surgical Treatment of Pelvic Organ Prolapse

    OpenAIRE

    Ellington, David R.; Richter, Holly E.

    2013-01-01

    Women are seeking care for pelvic organ prolapse (POP) in increasing numbers and a significant proportion of them will undergo a second repair for recurrence. This has initiated interest by both surgeons and industry to utilize and design prosthetic mesh materials to help augment longevity of prolapse repairs. Unfortunately, the introduction of transvaginal synthetic mesh kits for use in women was done without the benefit of Level 1 data to determine its utility compared to native tissue repa...

  14. 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.

  15. 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)

  16. 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.

  17. 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.

  18. 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

  19. Smooth Bézier surfaces over unstructured quadrilateral meshes

    CERN Document Server

    Bercovier, Michel

    2017-01-01

    Using an elegant mixture of geometry, graph theory and linear analysis, this monograph completely solves a problem lying at the interface of Isogeometric Analysis (IgA) and Finite Element Methods (FEM). The recent explosion of IgA, strongly tying Computer Aided Geometry Design to Analysis, does not easily apply to the rich variety of complex shapes that engineers have to design and analyse. Therefore new developments have studied the extension of IgA to unstructured unions of meshes, similar to those one can find in FEM. The following problem arises: given an unstructured planar quadrilateral mesh, construct a C1-surface, by piecewise Bézier or B-Spline patches defined over this mesh. This problem is solved for C1-surfaces defined over plane bilinear Bézier patches, the corresponding results for B-Splines then being simple consequences. The method can be extended to higher-order quadrilaterals and even to three dimensions, and the most recent developments in this direction are also mentioned here.

  20. Simulating control rod and fuel assembly motion using moving meshes

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, D. [Department of Electrical and Computer Engineering, McMaster University, 1280 Main Street West, Hamilton Ontario, L8S 4K1 (Canada)], E-mail: gilbertdw1@gmail.com; Roman, J.E. [Departamento de Sistemas Informaticos y Computacion, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Garland, Wm. J. [Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton Ontario, L8S 4K1 (Canada); Poehlman, W.F.S. [Department of Computing and Software, McMaster University, 1280 Main Street West, Hamilton Ontario, L8S 4K1 (Canada)

    2008-02-15

    A prerequisite for designing a transient simulation experiment which includes the motion of control and fuel assemblies is the careful verification of a steady state model which computes k{sub eff} versus assembly insertion distance. Previous studies in nuclear engineering have usually approached the problem of the motion of control rods with the use of nonlinear nodal models. Nodal methods employ special approximations for the leading and trailing cells of the moving assemblies to avoid the rod cusping problem which results from the naive volume weighted cell cross-section approximation. A prototype framework called the MOOSE has been developed for modeling moving components in the presence of diffusion phenomena. A linear finite difference model is constructed, solutions for which are computed by SLEPc, a high performance parallel eigenvalue solver. Design techniques for the implementation of a patched non-conformal mesh which links groups of sub-meshes that can move relative to one another are presented. The generation of matrices which represent moving meshes which conserve neutron current at their boundaries, and the performance of the framework when applied to model reactivity insertion experiments is also discussed.

  1. Secure Multicast Routing Algorithm for Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Rakesh Matam

    2016-01-01

    Full Text Available Multicast is an indispensable communication technique in wireless mesh network (WMN. Many applications in WMN including multicast TV, audio and video conferencing, and multiplayer social gaming use multicast transmission. On the other hand, security in multicast transmissions is crucial, without which the network services are significantly disrupted. Existing secure routing protocols that address different active attacks are still vulnerable due to subtle nature of flaws in protocol design. Moreover, existing secure routing protocols assume that adversarial nodes cannot share an out-of-band communication channel which rules out the possibility of wormhole attack. In this paper, we propose SEMRAW (SEcure Multicast Routing Algorithm for Wireless mesh network that is resistant against all known active threats including wormhole attack. SEMRAW employs digital signatures to prevent a malicious node from gaining illegitimate access to the message contents. Security of SEMRAW is evaluated using the simulation paradigm approach.

  2. Smart-Home Architecture Based on Bluetooth mesh Technology

    Science.gov (United States)

    Wan, Qing; Liu, Jianghua

    2018-03-01

    This paper describes the smart home network system based on Nordic nrf52832 device. Nrf52832 is new generation RF SOC device focus on sensor monitor and low power Bluetooth connection applications. In this smart home system, we set up a self-organizing network system which consists of one control node and a lot of monitor nodes. The control node manages the whole network works; the monitor nodes collect the sensor information such as light intensity, temperature, humidity, PM2.5, etc. Then update to the control node by Bluetooth mesh network. The design results show that the Bluetooth mesh wireless network system is flexible and construction cost is low, which is suitable for the communication characteristics of a smart home network. We believe it will be wildly used in the future.

  3. Automatic mesh adaptivity for CADIS and FW-CADIS neutronics modeling of difficult shielding problems

    International Nuclear Information System (INIS)

    Ibrahim, A. M.; Peplow, D. E.; Mosher, S. W.; Wagner, J. C.; Evans, T. M.; Wilson, P. P.; Sawan, M. E.

    2013-01-01

    The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. First, a macro-material approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm de-couples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility. Using these algorithms resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, obviating the need for a world-class super computer. (authors)

  4. Automatic mesh adaptivity for hybrid Monte Carlo/deterministic neutronics modeling of difficult shielding problems

    International Nuclear Information System (INIS)

    Ibrahim, Ahmad M.; Wilson, Paul P.H.; Sawan, Mohamed E.; Mosher, Scott W.; Peplow, Douglas E.; Wagner, John C.; Evans, Thomas M.; Grove, Robert E.

    2015-01-01

    The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. First, a macromaterial approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm decouples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility. Using these algorithms resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, eliminating the need for a world-class super computer

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Mesh Processing in Medical Image Analysis

    DEFF Research Database (Denmark)

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

  12. 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.

  13. 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...

  14. 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.

  15. Three-Dimensional Non-Coplanar Conformal Radiotherapy Yields Better Results Than Traditional Beam Arrangements for Adjuvant Treatment of Gastric Cancer

    International Nuclear Information System (INIS)

    Soyfer, Viacheslav; Corn, Benjamin W.; Melamud, Alex B.S.; Alani, Shlomi; Tempelhof, Haim; Agai, Reuben; Shmueli, Anat; Figer, Arie; Kovner, Felix

    2007-01-01

    Purpose: The current standard of adjuvant treatment for gastric cancer after curative resection is concurrent administration of radiotherapy and 5-fluorouracil-based chemotherapy. The radiation fields are often arranged as anterioposterior-posteroanterior opposed parallel fields with general recommendations for sparing at least two-thirds of one kidney. We investigated whether a better radiation distribution would be achievable with three-dimensional conformal approaches compared with the classic anterioposterior-posteroanterior fields. Methods and Materials: A total of 19 patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a non-coplanar four-field arrangement. In each case, parallel planning using an anterioposterior-posteroanterior arrangement and a four-field 'box' was performed, and the generated plans were subsequently compared for coverage of target volumes and doses to irradiated organs next to the tumor bed. A separate analysis was performed for kidneys exposed to greater and lower doses in each patient. The mean radiation dose and percentage of kidney volume receiving a dose >20 Gy were registered. Statistical analysis was performed using the two-tailed t test. Results: The clinical target volume was adequately covered in all three plans. In the greater-dose kidney group, all the differences were statistically significant with a benefit for the three-dimensional plan. In the lower-dose kidney group, the differences in the mean radiation dose did not reach the level of statistical significance, and the differences in the kidney volume receiving a dose >20 Gy showed a statistically significant benefit for the three-dimensional plan. Conclusion: Non-coplanar three-dimensional-based conformal planning for postoperative radiotherapy for gastric cancer provided the best results regarding kidney and spinal cord exposure with adequate clinical target volume coverage. This technique was readily implemented in clinical

  16. Three-dimensional non-coplanar conformal radiotherapy yields better results than traditional beam arrangements for adjuvant treatment of gastric cancer.

    Science.gov (United States)

    Soyfer, Viacheslav; Corn, Benjamin W; Melamud, Alex; Alani, Shlomi; Tempelhof, Haim; Agai, Reuben; Shmueli, Anat; Figer, Arie; Kovner, Felix

    2007-10-01

    The current standard of adjuvant treatment for gastric cancer after curative resection is concurrent administration of radiotherapy and 5-fluorouracil-based chemotherapy. The radiation fields are often arranged as anterioposterior-posteroanterior opposed parallel fields with general recommendations for sparing at least two-thirds of one kidney. We investigated whether a better radiation distribution would be achievable with three-dimensional conformal approaches compared with the classic anterioposterior-posteroanterior fields. A total of 19 patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a non-coplanar four-field arrangement. In each case, parallel planning using an anterioposterior-posteroanterior arrangement and a four-field "box" was performed, and the generated plans were subsequently compared for coverage of target volumes and doses to irradiated organs next to the tumor bed. A separate analysis was performed for kidneys exposed to greater and lower doses in each patient. The mean radiation dose and percentage of kidney volume receiving a dose >20 Gy were registered. Statistical analysis was performed using the two-tailed t test. The clinical target volume was adequately covered in all three plans. In the greater-dose kidney group, all the differences were statistically significant with a benefit for the three-dimensional plan. In the lower-dose kidney group, the differences in the mean radiation dose did not reach the level of statistical significance, and the differences in the kidney volume receiving a dose >20 Gy showed a statistically significant benefit for the three-dimensional plan. Non-coplanar three-dimensional-based conformal planning for postoperative radiotherapy for gastric cancer provided the best results regarding kidney and spinal cord exposure with adequate clinical target volume coverage. This technique was readily implemented in clinical practice.

  17. Seeking new surgical predictors of mesh exposure after transvaginal mesh repair.

    Science.gov (United States)

    Wu, Pei-Ying; Chang, Chih-Hung; Shen, Meng-Ru; Chou, Cheng-Yang; Yang, Yi-Ching; Huang, Yu-Fang

    2016-10-01

    The purpose of this study was to explore new preventable risk factors for mesh exposure. A retrospective review of 92 consecutive patients treated with transvaginal mesh (TVM) in the urogynecological unit of our university hospital. An analysis of perioperative predictors was conducted in patients after vaginal repairs using a type 1 mesh. Mesh complications were recorded according to International Urogynecological Association (IUGA) definitions. Mesh-exposure-free durations were calculated by using the Kaplan-Meier method and compared between different closure techniques using log-rank test. Hazard ratios (HR) of predictors for mesh exposure were estimated by univariate and multivariate analyses using Cox proportional hazards regression models. The median surveillance interval was 24.1 months. Two late occurrences were found beyond 1 year post operation. No statistically significant correlation was observed between mesh exposure and concomitant hysterectomy. Exposure risks were significantly higher in patients with interrupted whole-layer closure in univariate analysis. In the multivariate analysis, hematoma [HR 5.42, 95 % confidence interval (CI) 1.26-23.35, P = 0.024), Prolift mesh (HR 5.52, 95 % CI 1.15-26.53, P = 0.033), and interrupted whole-layer closure (HR 7.02, 95 % CI 1.62-30.53, P = 0.009) were the strongest predictors of mesh exposure. Findings indicate the risks of mesh exposure and reoperation may be prevented by avoiding hematoma, large amount of mesh, or interrupted whole-layer closure in TVM surgeries. If these risk factors are prevented, hysterectomy may not be a relative contraindication for TVM use. We also provide evidence regarding mesh exposure and the necessity for more than 1 year of follow-up and preoperative counselling.

  18. 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

  19. 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...

  20. 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

  1. [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.

  2. Quadrilateral mesh fitting that preserves sharp features based on multi-normals for Laplacian energy

    Directory of Open Access Journals (Sweden)

    Yusuke Imai

    2014-04-01

    Full Text Available Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

  3. 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.

  4. Milestone Deliverable: FY18-Q1: 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)

    2017-12-01

    This milestone was focused on deploying and verifying a “sliding-mesh interface,” and establishing baseline timings for blade-resolved simulations of a sub-MW-scale turbine. In the ExaWind project, we are developing both sliding-mesh and overset-mesh approaches for handling the rotating blades in an operating wind turbine. In the sliding-mesh approach, the turbine rotor and its immediate surrounding fluid are captured in a “disk” that is embedded in the larger fluid domain. The embedded fluid is simulated in a coordinate system that rotates with the rotor. It is important that the coupling algorithm (and its implementation) between the rotating and inertial discrete models maintains the accuracy of the numerical methods on either side of the interface, i.e., the interface is “design order.”

  5. 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...

  6. 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

  7. Numerical simulation for quenching meshes with TONUS platform

    International Nuclear Information System (INIS)

    Bin, Chen; Hongxing, Yu

    2009-01-01

    For mitigation of hydrogen risks during severe accidents to protect the integrity of containment, PAR and ignitors are used in current advanced nuclear power plants. But multiple combustions induced by ignitors and consequent DDT phenomena are not practically eliminated. An innovative design call 'quenching meshes' is considered to confine hydrogen flame within one compartment by metallic meshes, so that hazardous flame propagation can be prevented. The numerical simulation results based on discretization of the full Navier-Stokes equations with global one-step reaction represented by Arrhenius laminar combustion model have shown the possibility of flame quenching 'numerically'. This is achieved via multiplication of the combustion rate expression by a Heaviside function having an ignition temperature as a parameter. Qualitative behavior of the computed flow shows that the flame velocity diminishes while passing through a quenching mesh, while qualitative analysis based on the energy balance reveals the mechanism of flame quenching. All the above analysis has been performed for a stoichiometric mixture and normal initial pressure and temperature for initial conditions. For further research we would like to suggest the investigation of the influence of the mixture composition, initial pressure and/or temperature on the quenching criteria

  8. 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.

  9. Effects on Diagnostic Parameters After Removing Additional Synchronous Gear Meshes

    Science.gov (United States)

    Decker, Harry J.

    2003-01-01

    Gear cracks are typically difficult to diagnose with sufficient time before catastrophic damage occurs. Significant damage must be present before algorithms appear to be able to detect the damage. Frequently there are multiple gear meshes on a single shaft. Since they are all synchronous with the shaft frequency, the commonly used synchronous averaging technique is ineffective in removing other gear mesh effects. Carefully applying a filter to these extraneous gear mesh frequencies can reduce the overall vibration signal and increase the accuracy of commonly used vibration metrics. The vibration signals from three seeded fault tests were analyzed using this filtering procedure. Both the filtered and unfiltered vibration signals were then analyzed using commonly used fault detection metrics and compared. The tests were conducted on aerospace quality spur gears in a test rig. The tests were conducted at speeds ranging from 2500 to 5000 revolutions per minute and torques from 184 to 228 percent of design load. The inability to detect these cracks with high confidence results from the high loading which is causing fast fracture as opposed to stable crack growth. The results indicate that these techniques do not currently produce an indication of damage that significantly exceeds experimental scatter.

  10. 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...

  11. 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.

  12. DNA rendering of polyhedral meshes at the nanoscale

    Science.gov (United States)

    Benson, Erik; Mohammed, Abdulmelik; Gardell, Johan; Masich, Sergej; Czeizler, Eugen; Orponen, Pekka; Högberg, Björn

    2015-07-01

    It was suggested more than thirty years ago that Watson-Crick base pairing might be used for the rational design of nanometre-scale structures from nucleic acids. Since then, and especially since the introduction of the origami technique, DNA nanotechnology has enabled increasingly more complex structures. But although general approaches for creating DNA origami polygonal meshes and design software are available, there are still important constraints arising from DNA geometry and sense/antisense pairing, necessitating some manual adjustment during the design process. Here we present a general method of folding arbitrary polygonal digital meshes in DNA that readily produces structures that would be very difficult to realize using previous approaches. The design process is highly automated, using a routeing algorithm based on graph theory and a relaxation simulation that traces scaffold strands through the target structures. Moreover, unlike conventional origami designs built from close-packed helices, our structures have a more open conformation with one helix per edge and are therefore stable under the ionic conditions usually used in biological assays.

  13. 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.

  14. Analisis Kinerja EIGRP dan OSPF pada Topologi Ring dan Mesh

    Directory of Open Access Journals (Sweden)

    DWI ARYANTA

    2014-01-01

    Full Text Available ABSTRAK EIGRP (Enhanced Interior Gateway Routing Protocol dan OSPF (Open Shortest Path Fisrt adalah routing protokol yang banyak digunakan pada suatu jaringan komputer. EIGRP hanya dapat digunakan pada perangkat Merk CISCO, sedangkan OSPF dapat digunakan pada semua merk jaringan. Pada penelitian ini dibandingkan delay dan rute dari kedua routing protokol yang diimplementasikan pada topologi Ring dan Mesh. Cisco Packet Tracer 5.3 digunakan untuk mensimulasikan kedua routing protokol ini. Skenario pertama adalah perancangan jaringan kemudian dilakukan pengujian waktu delay 100 kali dalam 5 kasus. Skenario kedua dilakukan pengujian trace route untuk mengetahui jalur yang dilewati paket data lalu memutus link utama. Pada skenario kedua juga dilakukan perbandingan nilai metric dan cost hasil simulasi dengan perhitungan rumus. Skenario ketiga dilakukan pengujian waktu konvergensi untuk setiap routing protokol pada setiap topologi. Hasilnya EIGRP lebih cepat 386 µs daripada OSPF untuk topologi Ring sedangkan OSPF lebih cepat 453 µs daripada EIGRP untuk topologi Mesh. Hasil trace route menunjukan rute yang dipilih oleh routing protokol yaitu nilai metric dan cost yang terkecil. Waktu konvergensi rata-rata topologi Ring pada EIGRP sebesar 12,75 detik dan 34,5 detik pada OSPF sedangkan topologi Mesh di EIGRP sebesar 13 detik dan 35,25 detik di OSPF. Kata Kunci: EIGRP, OSPF, Packet Tracer 5.3, Ring, Mesh, Konvergensi ABSTRACT EIGRP (Enhanced Interior Gateway Routing Protocol and OSPF (Open Shortest Path Fisrt is the routing protocol that is widely used in a computer network. EIGRP can only be used on devices Brand CISCO, while OSPF can be used on all brands of network. In this study comparison of both the delay and the routing protocol implemented on Ring and Mesh topology. Cisco Packet Tracer 5.3 is used to simulate both the routing protocol. The first scenario is the design of the network and then do the test of time delay 100 times in 5 cases. The

  15. Analisis Kinerja EIGRP dan OSPF pada Topologi Ring dan Mesh

    Directory of Open Access Journals (Sweden)

    DWI ARYANTA

    2016-02-01

    Full Text Available ABSTRAK EIGRP (Enhanced Interior Gateway Routing Protocol dan OSPF (Open Shortest Path Fisrt adalah routing protokol yang banyak digunakan pada suatu jaringan komputer. EIGRP hanya dapat digunakan pada perangkat Merk CISCO, sedangkan OSPF dapat digunakan pada semua merk jaringan. Pada penelitian ini dibandingkan delay dan rute dari kedua routing protokol yang diimplementasikan pada topologi Ring dan Mesh. Cisco Packet Tracer 5.3 digunakan untuk mensimulasikan kedua routing protokol ini. Skenario pertama adalah perancangan jaringan kemudian dilakukan pengujian waktu delay 100 kali dalam 5 kasus. Skenario kedua dilakukan pengujian trace route untuk mengetahui jalur yang dilewati paket data lalu memutus link utama. Pada skenario kedua juga dilakukan perbandingan nilai metric dan cost hasil simulasi dengan perhitungan rumus. Skenario ketiga dilakukan pengujian waktu konvergensi untuk setiap routing protokol pada setiap topologi. Hasilnya EIGRP lebih cepat 386 µs daripada OSPF untuk topologi Ring sedangkan OSPF lebih cepat 453 µs daripada EIGRP untuk topologi Mesh. Hasil trace route menunjukan rute yang dipilih oleh routing protokol yaitu nilai metric dan cost yang terkecil. Waktu konvergensi rata-rata topologi Ring pada EIGRP sebesar 12,75 detik dan 34,5 detik pada OSPF sedangkan topologi Mesh di EIGRP sebesar 13 detik dan 35,25 detik di OSPF. Kata Kunci : EIGRP, OSPF, Packet Tracer 5.3, Ring, Mesh, Konvergensi ABSTRACT EIGRP (Enhanced Interior Gateway Routing Protocol and OSPF (Open Shortest Path Fisrt is the routing protocol that is widely used in a computer network. EIGRP can only be used on devices Brand CISCO, while OSPF can be used on all brands of network. In this study comparison of both the delay and the routing protocol implemented on Ring and Mesh topology. Cisco Packet Tracer 5.3 is used to simulate both the routing protocol. The first scenario is the design of the network and then do the test of time delay 100 times in 5 cases. The

  16. 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.

  17. 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

  18. Device Performance Improvement of Double-Pass Wire Mesh Packed Solar Air Heaters under Recycling Operation Conditions

    Directory of Open Access Journals (Sweden)

    Chii-Dong Ho

    2016-01-01

    Full Text Available The improvement of device performance of a recycling solar air heater featuring a wire mesh packing was investigated experimentally and theoretically. The application of the wire mesh packing and recycle-effect concept to the present study were proposed aiming to strengthen the convective heat-transfer coefficient due to increased turbulence. Comparisons were made among different designs, including the single-pass, flat-plate double-pass and recycling double-pass wire mesh packed operations. The collector efficiency of the recycling double-pass wire mesh packed solar air heater was much higher than that of the other configurations for various recycle ratios and mass flow rates scenarios. The power consumption increment due to implementing wire mesh in solar air heaters was also discussed considering the economic feasibility. A fairly good agreement between theoretical predictions and experimental measurements was achieved with an analyzed error of 1.07%–9.32%.

  19. 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.

  20. Short-term outcomes of the transvaginal minimal mesh procedure for pelvic organ prolapse

    Directory of Open Access Journals (Sweden)

    Naoko Takazawa

    2018-03-01

    Full Text Available Purpose: This study aimed to evaluate the clinical outcomes and complications of transvaginal minimal mesh repair without using commercially available kits for treatment of pelvic organ prolapse (POP. Materials and Methods: This retrospective cohort study involved 91 women who underwent surgical management of POP with originally designed small mesh between July 2014 and August 2015. This mesh is 56% smaller than the mesh widely used in Japan, and it has only two arms delivered into each right and left sacrospinous ligament. The main study outcome was the anatomic cure rate defined as recurrence of POP quantification (POP-Q stage II or more. We also assessed changes in the overactive bladder symptom score (OABSS and prolapse quality of life questionnaire (P-QOL and evaluated adverse events. Finally, we compared patient backgrounds between the patients with and without recurrence. Results: Prolapse recurred in 10 of 91 patients (11.0%, and all patients with recurrence were diagnosed as POP-Q stage II. As adverse events, only mesh erosion occurred in two (2.2% and pelvic pain in one (1.1% of the 91 patients. The OABSS and P-QOL were significantly improved by the operation. When we compared patient backgrounds between the patients with and without recurrence, body mass index was the only factor influencing affecting recurrence. Conclusions: Transvaginal minimal mesh repair resulted in successful outcomes with low mesh-related complications and anatomic recurrence at one year. Furthermore, significant improvement in QOL was offered by this procedure. Our minimal mesh technique should be considered as one treatment option for the management of POP.

  1. Short-term outcomes of the transvaginal minimal mesh procedure for pelvic organ prolapse.

    Science.gov (United States)

    Takazawa, Naoko; Fujisaki, Akiko; Yoshimura, Yasukuni; Tsujimura, Akira; Horie, Shigeo

    2018-03-01

    This study aimed to evaluate the clinical outcomes and complications of transvaginal minimal mesh repair without using commercially available kits for treatment of pelvic organ prolapse (POP). This retrospective cohort study involved 91 women who underwent surgical management of POP with originally designed small mesh between July 2014 and August 2015. This mesh is 56% smaller than the mesh widely used in Japan, and it has only two arms delivered into each right and left sacrospinous ligament. The main study outcome was the anatomic cure rate defined as recurrence of POP quantification (POP-Q) stage II or more. We also assessed changes in the overactive bladder symptom score (OABSS) and prolapse quality of life questionnaire (P-QOL) and evaluated adverse events. Finally, we compared patient backgrounds between the patients with and without recurrence. Prolapse recurred in 10 of 91 patients (11.0%), and all patients with recurrence were diagnosed as POP-Q stage II. As adverse events, only mesh erosion occurred in two (2.2%) and pelvic pain in one (1.1%) of the 91 patients. The OABSS and P-QOL were significantly improved by the operation. When we compared patient backgrounds between the patients with and without recurrence, body mass index was the only factor influencing affecting recurrence. Transvaginal minimal mesh repair resulted in successful outcomes with low mesh-related complications and anatomic recurrence at one year. Furthermore, significant improvement in QOL was offered by this procedure. Our minimal mesh technique should be considered as one treatment option for the management of POP.

  2. 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

  3. 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....

  4. 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....

  5. Advantages and disadvantages of using non-coplanar techniques in radiotherapy of the abdomen formed 3D; Ventajas e inconvenientes del uso de tecnicas con coplanares en radiaoterpia 3D conformada de abdomen

    Energy Technology Data Exchange (ETDEWEB)

    Urena Llinares, A.; Castro Ramirez, I.; Iborra Oquendo, M. A; Quinones Rodriguez, L. A.; Angulo Pain, E.

    2011-07-01

    3D Radiotherapy locations abdomen, especially in pancreas and stomach cancers is often extremely difficult if we are to meet the dose constraints to organs at risk due to proximity and many of these (liver, kidneys, intestines, lungs, bone. ..). Of these, the most critical are the kidneys, which also present values of tolerance, in most cases difficult to meet. This is done in our hospital are using non-coplanar techniques performing well both as coating PTV dose to both kidneys.

  6. Role of higher-multipole deformations and noncoplanarity in the decay of the compound nucleus *220Th within the dynamical cluster-decay model

    Science.gov (United States)

    Hemdeep, Chopra, Sahila; Kaur, Arshdeep; Kaushal, Pooja; Gupta, Raj K.

    2018-04-01

    Background: The formation and decay of the *220Th compound nucleus (CN) formed via some entrance channels (16O+204Pb,40Ar+180Hf,48Ca+172Yb,82Se+138Ba ) at near barrier energies has been studied within the dynamical cluster-decay model (DCM) [Hemdeep et al. Phys. Rev. C 95, 014609 (2017), 10.1103/PhysRevC.95.044603], for quadrupole deformations (β2 i) and "optimum" orientations (θopt) of the two nuclei or decay fragments lying in the same plane (coplanar nuclei, Φ =0∘ ). Purpose: We aim to investigate the role of higher-multipole deformations, the octupole (β3 i) and hexadecupole (β4 i), and "compact" orientations (θc i) together with the noncoplanarity degree of freedom (Φc) in the noncompound nucleus (nCN) cross section, already observed in the above mentioned study with quadrupole deformations (β2 i) alone, the Φ =0∘ case. Methods: The dynamical cluster-decay model (DCM), based on the quantum mechanical fragmentation theory (QMFT), is used to analyze the decay channel cross sections σx n for various experimentally studied entrance channels. The parameter Ra (equivalently, the neck length Δ R in Ra=R1+R2+Δ R ), which fixes both the preformation and penetration paths, is used to best fit both unobserved (1 n ,2 n ) and observed (3 n -5 n ) decay channel cross sections, keeping the root-mean-square (r.m.s) deviation to the minimum, which allows us to predict the nCN effects, if any, and fusion-fission (ff) cross sections in various reactions at different CN excitation energies E*. Results: For the decay of CN *220Th, the mass fragmentation potential V (Ai ) and preformation yields P0( Ai ) show an asymmetric fission mass distribution, in agreement with one observed in experiments, independent of adding or not adding (β3 i,β4 i ), and irrespective of large changes (by 36° and 34°), respectively, in "compact" orientations θc i and noncoplanarity Φc, and also in the potential energy surface V (Ai ) in light mass (1 n -5 n ) decays. Whereas the 3 n

  7. Unstructured Adaptive Meshes: Bad for Your Memory?

    Science.gov (United States)

    Biswas, Rupak; Feng, Hui-Yu; VanderWijngaart, Rob

    2003-01-01

    This viewgraph presentation explores the need for a NASA Advanced Supercomputing (NAS) parallel benchmark for problems with irregular dynamical memory access. This benchmark is important and necessary because: 1) Problems with localized error source benefit from adaptive nonuniform meshes; 2) Certain machines perform poorly on such problems; 3) Parallel implementation may provide further performance improvement but is difficult. Some examples of problems which use irregular dynamical memory access include: 1) Heat transfer problem; 2) Heat source term; 3) Spectral element method; 4) Base functions; 5) Elemental discrete equations; 6) Global discrete equations. Nonconforming Mesh and Mortar Element Method are covered in greater detail in this presentation.

  8. Local adaptive mesh refinement for shock hydrodynamics

    International Nuclear Information System (INIS)

    Berger, M.J.; Colella, P.; Lawrence Livermore Laboratory, Livermore, 94550 California)

    1989-01-01

    The aim of this work is the development of an automatic, adaptive mesh refinement strategy for solving hyperbolic conservation laws in two dimensions. There are two main difficulties in doing this. The first problem is due to the presence of discontinuities in the solution and the effect on them of discontinuities in the mesh. The second problem is how to organize the algorithm to minimize memory and CPU overhead. This is an important consideration and will continue to be important as more sophisticated algorithms that use data structures other than arrays are developed for use on vector and parallel computers. copyright 1989 Academic Press, Inc

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Mesh size in Lichtenstein repair: a systematic review and meta-analysis to determine the importance of mesh size.

    Science.gov (United States)

    Seker, D; Oztuna, D; Kulacoglu, H; Genc, Y; Akcil, M

    2013-04-01

    Small mesh size has been recognized as one of the factors responsible for recurrence after Lichtenstein hernia repair due to insufficient coverage or mesh shrinkage. The Lichtenstein Hernia Institute recommends a 7 × 15 cm mesh that can be trimmed up to 2 cm from the lateral side. We performed a systematic review to determine surgeons' mesh size preference for the Lichtenstein hernia repair and made a meta-analysis to determine the effect of mesh size, mesh type, and length of follow-up time on recurrence. Two medical databases, PubMed and ISI Web of Science, were systematically searched using the key word "Lichtenstein repair." All full text papers were selected. Publications mentioning mesh size were brought for further analysis. A mesh surface area of 90 cm(2) was accepted as the threshold for defining the mesh as small or large. Also, a subgroup analysis for recurrence pooled proportion according to the mesh size, mesh type, and follow-up period was done. In total, 514 papers were obtained. There were no prospective or retrospective clinical studies comparing mesh size and clinical outcome. A total of 141 papers were duplicated in both databases. As a result, 373 papers were obtained. The full text was available in over 95 % of papers. Only 41 (11.2 %) papers discussed mesh size. In 29 studies, a mesh larger than 90 cm(2) was used. The most frequently preferred commercial mesh size was 7.5 × 15 cm. No papers mentioned the size of the mesh after trimming. There was no information about the relationship between mesh size and patient BMI. The pooled proportion in recurrence for small meshes was 0.0019 (95 % confidence interval: 0.007-0.0036), favoring large meshes to decrease the chance of recurrence. Recurrence becomes more marked when follow-up period is longer than 1 year (p < 0.001). Heavy meshes also decreased recurrence (p = 0.015). This systematic review demonstrates that the size of the mesh used in Lichtenstein hernia repair is rarely

  15. Plan quality comparison between 4-arc and 6-arc noncoplanar volumetric modulated arc stereotactic radiotherapy for the treatment of multiple brain metastases.

    Science.gov (United States)

    Yoshio, Kotaro; Mitsuhashi, Toshiharu; Wakita, Akihisa; Kitayama, Takahiro; Hisazumi, Kento; Inoue, Daisaku; Shiode, Tsuyoki; Akaki, Shiro; Kanazawa, Susumu

    2018-01-04

    To compare the plans of 4-arc and 6-arc noncoplanar volumetric modulated arc stereotactic radiotherapy (VMA-SRT) for multiple brain metastases and to investigate the cutoff value for the tumor number and volume for 6-arc rather than 4-arc VMA-SRT. We identified 24 consecutive multiple-target cases (3 to 19 targets in each case) with 189 total targets. We constructed plans using both 4- and 6-arc noncoplanar VMA-SRT. The prescribed dose was 36 Gy/6 fr, and it was delivered to 95% of the planning target volume (PTV). The plans were evaluated for the dose conformity using the Radiation Therapy Oncology Group and Paddick conformity indices (RCI and PCI), fall-off (Paddick gradient index [PGI]), and the normal brain dose. The median (range) RCI, PCI, and PGI was 0.94 (0.92 to 0.99), 0.89 (0.77 to 0.94), and 3.75 (2.24 to 6.54) for the 4-arc plan and 0.94 (0.91 to 0.98), 0.89 (0.76 to 0.94), and 3.65 (2.24 to 6.5) for the 6-arc plan, respectively. The median (range) of the normal brain dose was 910.3 cGy (381.4 to 1268.9) for the 4-arc plan and 898.8 cGy (377 to 1252.9) for the 6-arc plan. The PGI of the 6-arc plan was significantly superior to that of the 4-arc plan (p = 0.0076), and the optimal cutoff values for the tumor number and volume indicative of 6-arc (and not 4-arc) VMA-SRT were cases with ≥ 5 metastases and a PTV of ≥ 12.9 mL, respectively. The PCI values, however, showed no significant difference between the 2 plans. We believe these results will help in considering the use of 6-arc VMA-SRT for multiple brain metastases. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  16. Noncoplanar Beam Angle Class Solutions to Replace Time-Consuming Patient-Specific Beam Angle Optimization in Robotic Prostate Stereotactic Body Radiation Therapy

    International Nuclear Information System (INIS)

    Rossi, Linda; Breedveld, Sebastiaan; Aluwini, Shafak; Heijmen, Ben

    2015-01-01

    Purpose: To investigate development of a recipe for the creation of a beam angle class solution (CS) for noncoplanar prostate stereotactic body radiation therapy to replace time-consuming individualized beam angle selection (iBAS) without significant loss in plan quality, using the in-house “Erasmus-iCycle” optimizer for fully automated beam profile optimization and iBAS. Methods and Materials: For 30 patients, Erasmus-iCycle was first used to generate 15-, 20-, and 25-beam iBAS plans for a CyberKnife equipped with a multileaf collimator. With these plans, 6 recipes for creation of beam angle CSs were investigated. Plans of 10 patients were used to create CSs based on the recipes, and the other 20 to independently test them. For these tests, Erasmus-iCycle was also used to generate intensity modulated radiation therapy plans for the fixed CS beam setups. Results: Of the tested recipes for CS creation, only 1 resulted in 15-, 20-, and 25-beam noncoplanar CSs without plan deterioration compared with iBAS. For the patient group, mean differences in rectum D 1cc , V 60GyEq , V 40GyEq , and D mean between 25-beam CS plans and 25-beam plans generated with iBAS were 0.2 ± 0.4 Gy, 0.1% ± 0.2%, 0.2% ± 0.3%, and 0.1 ± 0.2 Gy, respectively. Differences between 15- and 20-beam CS and iBAS plans were also negligible. Plan quality for CS plans relative to iBAS plans was also preserved when narrower planning target volume margins were arranged and when planning target volume dose inhomogeneity was decreased. Using a CS instead of iBAS reduced the computation time by a factor of 14 to 25, mainly depending on beam number, without loss in plan quality. Conclusions: A recipe for creation of robust beam angle CSs for robotic prostate stereotactic body radiation therapy has been developed. Compared with iBAS, computation times decreased by a factor 14 to 25. The use of a CS may avoid long planning times without losses in plan quality

  17. SU-F-BRB-10: A Statistical Voxel Based Normal Organ Dose Prediction Model for Coplanar and Non-Coplanar Prostate Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Tran, A; Yu, V; Nguyen, D; Woods, K; Low, D; Sheng, K [UCLA, Los Angeles, CA (United States)

    2015-06-15

    Purpose: Knowledge learned from previous plans can be used to guide future treatment planning. Existing knowledge-based treatment planning methods study the correlation between organ geometry and dose volume histogram (DVH), which is a lossy representation of the complete dose distribution. A statistical voxel dose learning (SVDL) model was developed that includes the complete dose volume information. Its accuracy of predicting volumetric-modulated arc therapy (VMAT) and non-coplanar 4π radiotherapy was quantified. SVDL provided more isotropic dose gradients and may improve knowledge-based planning. Methods: 12 prostate SBRT patients originally treated using two full-arc VMAT techniques were re-planned with 4π using 20 intensity-modulated non-coplanar fields to a prescription dose of 40 Gy. The bladder and rectum voxels were binned based on their distances to the PTV. The dose distribution in each bin was resampled by convolving to a Gaussian kernel, resulting in 1000 data points in each bin that predicted the statistical dose information of a voxel with unknown dose in a new patient without triaging information that may be collectively important to a particular patient. We used this method to predict the DVHs, mean and max doses in a leave-one-out cross validation (LOOCV) test and compared its performance against lossy estimators including mean, median, mode, Poisson and Rayleigh of the voxelized dose distributions. Results: SVDL predicted the bladder and rectum doses more accurately than other estimators, giving mean percentile errors ranging from 13.35–19.46%, 4.81–19.47%, 22.49–28.69%, 23.35–30.5%, 21.05–53.93% for predicting mean, max dose, V20, V35, and V40 respectively, to OARs in both planning techniques. The prediction errors were generally lower for 4π than VMAT. Conclusion: By employing all dose volume information in the SVDL model, the OAR doses were more accurately predicted. 4π plans are better suited for knowledge-based planning than

  18. Noncoplanar Beam Angle Class Solutions to Replace Time-Consuming Patient-Specific Beam Angle Optimization in Robotic Prostate Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Linda, E-mail: l.rossi@erasmusmc.nl; Breedveld, Sebastiaan; Aluwini, Shafak; Heijmen, Ben

    2015-07-15

    Purpose: To investigate development of a recipe for the creation of a beam angle class solution (CS) for noncoplanar prostate stereotactic body radiation therapy to replace time-consuming individualized beam angle selection (iBAS) without significant loss in plan quality, using the in-house “Erasmus-iCycle” optimizer for fully automated beam profile optimization and iBAS. Methods and Materials: For 30 patients, Erasmus-iCycle was first used to generate 15-, 20-, and 25-beam iBAS plans for a CyberKnife equipped with a multileaf collimator. With these plans, 6 recipes for creation of beam angle CSs were investigated. Plans of 10 patients were used to create CSs based on the recipes, and the other 20 to independently test them. For these tests, Erasmus-iCycle was also used to generate intensity modulated radiation therapy plans for the fixed CS beam setups. Results: Of the tested recipes for CS creation, only 1 resulted in 15-, 20-, and 25-beam noncoplanar CSs without plan deterioration compared with iBAS. For the patient group, mean differences in rectum D{sub 1cc}, V{sub 60GyEq}, V{sub 40GyEq}, and D{sub mean} between 25-beam CS plans and 25-beam plans generated with iBAS were 0.2 ± 0.4 Gy, 0.1% ± 0.2%, 0.2% ± 0.3%, and 0.1 ± 0.2 Gy, respectively. Differences between 15- and 20-beam CS and iBAS plans were also negligible. Plan quality for CS plans relative to iBAS plans was also preserved when narrower planning target volume margins were arranged and when planning target volume dose inhomogeneity was decreased. Using a CS instead of iBAS reduced the computation time by a factor of 14 to 25, mainly depending on beam number, without loss in plan quality. Conclusions: A recipe for creation of robust beam angle CSs for robotic prostate stereotactic body radiation therapy has been developed. Compared with iBAS, computation times decreased by a factor 14 to 25. The use of a CS may avoid long planning times without losses in plan quality.

  19. 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.

  20. Using small meshed collecting bags on trawls to quantify trawls seabed disturbance of aquatic organisms

    DEFF Research Database (Denmark)

    Krag, Ludvig Ahm

    impact on commercial fishing grounds. In this study we develop and test small-meshed collecting bags designed to retain juvenile fish and benthic megafauna. The collecting bags are mounted in the wings and body of the trawl. The catches in the collection bags provide information of the species and size...... in the mechanical effect, such as penetration depth of the ground gear of different trawl designs. Collecting bags are also mounted to the different sections of the trawl in pairs, one to collect the organisms that pass through the trawl meshes and one to collect the population. Standard selectivity analyses...

  1. A Full Mesh ATCA-based General Purpose Data Processing Board (Pulsar II)

    Energy Technology Data Exchange (ETDEWEB)

    Ajuha, S. [Univ. of Sao Paulo (Brazil); et al.

    2017-06-29

    The Pulsar II is a custom ATCA full mesh enabled FPGA-based processor board which has been designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth interconnections. The design has been motivated by silicon-based tracking trigger needs for LHC experiments. In this technical memo we describe the Pulsar II hardware and its performance, such as the performance test results with full mesh backplanes from different vendors, how the backplane is used for the development of low-latency time-multiplexed data transfer schemes and how the inter-shelf and intra-shelf synchronization works.

  2. 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...

  3. A Full Mesh ATCA-based General Purpose Data Processing Board (Pulsar II)

    CERN Document Server

    Ajuha, S; Costa de Paiva, Thiago; Das, Souvik; Eusebi, Ricardo; Finotti Ferreira, Vitor; Hahn, Kristian; Hu, Zhen; Jindariani, Sergo; Konigsberg, Jacobo; Liu, Tiehui Ted; Low, Jia Fu; Okumura, Yasuyuki; Olsen, Jamieson; Arruda Ramalho, Lucas; Rossin, Roberto; Ristori, Luciano; Akira Shinoda, Ailton; Tran, Nhan; Trovato, Marco; Ulmer, Keith; Vaz, Mario; Wen, Xianshan; Wu, Jin-Yuan; Xu, Zijun; Yin, Han; Zorzetti, Silvia

    2017-01-01

    The Pulsar II is a custom ATCA full mesh enabled FPGA-based processor board which has been designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth interconnections. The design has been motivated by silicon-based tracking trigger needs for LHC experiments. In this technical memo we describe the Pulsar II hardware and its performance, such as the performance test results with full mesh backplanes from di↵erent vendors, how the backplane is used for the development of low-latency time-multiplexed data transfer schemes and how the inter-shelf and intra-shelf synchronization works.

  4. 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

  5. Markov Random Fields on Triangle Meshes

    DEFF Research Database (Denmark)

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

    2010-01-01

    In this paper we propose a novel anisotropic smoothing scheme based on Markov Random Fields (MRF). Our scheme is formulated as two coupled processes. A vertex process is used to smooth the mesh by displacing the vertices according to a MRF smoothness prior, while an independent edge process label...

  6. Performance Evaluation of Coded Meshed Networks

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. Solid Mesh Registration for Radiotherapy Treatment Planning

    DEFF Research Database (Denmark)

    Noe, Karsten Østergaard; Sørensen, Thomas Sangild

    2010-01-01

    We present an algorithm for solid organ registration of pre-segmented data represented as tetrahedral meshes. Registration of the organ surface is driven by force terms based on a distance field representation of the source and reference shapes. Registration of internal morphology is achieved usi...

  8. 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

  9. 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 ...

  10. 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 ...

  11. 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,.

  12. Evaluation of accuracy about 2D vs 3D real-time position management system based on couch rotation when non-coplanar respiratory gated radiation therapy

    International Nuclear Information System (INIS)

    Kwon, Kyung Tae; Kim, Jung Soo; Sim, Hyun Sun; Min, Jung Whan; Son, Soon Yong; Han, Dong Kyoon

    2016-01-01

    Because of non-coplanar therapy with couch rotation in respiratory gated radiation therapy, the recognition of marker movement due to the change in the distance between the infrared camera and the marker due to the rotation of the couch is called RPM (Real-time The purpose of this paper is to evaluate the accuracy of motion reflections (baseline changes) of 2D gating configuration (two dot marker block) and 3D gating configuration (six dot marker block). The motion was measured by varying the couch angle in the clockwise and counterclockwise directions by 10° in the 2D gating configuration. In the 3D gating configuration, the couch angle was changed by 10° in the clockwise direction and compared with the baseline at the reference 0°. The reference amplitude was 1.173 to 1.165, the couch angle at 20° was 1.132, and the couch angle at 1.0° was 1.083. At 350° counterclockwise, the reference amplitude was 1.168 to 1.157, the couch angle at 340° was 1.124, and the couch angle at 330° was 1.079. In this study, the phantom is used to quantitatively evaluate the value of the amplitude according to couch change

  13. Evaluation of accuracy about 2D vs 3D real-time position management system based on couch rotation when non-coplanar respiratory gated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kyung Tae; Kim, Jung Soo [Dongnam Health University, Suwon (Korea, Republic of); Sim, Hyun Sun [College of Health Sciences, Korea University, Seoul (Korea, Republic of); Min, Jung Whan [Shingu University College, Sungnam (Korea, Republic of); Son, Soon Yong [Wonkwang Health Science University, Iksan (Korea, Republic of); Han, Dong Kyoon [College of Health Sciences, EulJi University, Daejeon (Korea, Republic of)

    2016-12-15

    Because of non-coplanar therapy with couch rotation in respiratory gated radiation therapy, the recognition of marker movement due to the change in the distance between the infrared camera and the marker due to the rotation of the couch is called RPM (Real-time The purpose of this paper is to evaluate the accuracy of motion reflections (baseline changes) of 2D gating configuration (two dot marker block) and 3D gating configuration (six dot marker block). The motion was measured by varying the couch angle in the clockwise and counterclockwise directions by 10° in the 2D gating configuration. In the 3D gating configuration, the couch angle was changed by 10° in the clockwise direction and compared with the baseline at the reference 0°. The reference amplitude was 1.173 to 1.165, the couch angle at 20° was 1.132, and the couch angle at 1.0° was 1.083. At 350° counterclockwise, the reference amplitude was 1.168 to 1.157, the couch angle at 340° was 1.124, and the couch angle at 330° was 1.079. In this study, the phantom is used to quantitatively evaluate the value of the amplitude according to couch change.

  14. Reconsidering the advantages of the three-dimensional representation of the interferometric transform for imaging with non-coplanar baselines and wide fields of view

    Science.gov (United States)

    Smith, D. M. P.; Young, A.; Davidson, D. B.

    2017-07-01

    Radio telescopes with baselines that span thousands of kilometres and with fields of view that span tens of degrees have been recently deployed, such as the Low Frequency Array, and are currently being developed, such as the Square Kilometre Array. Additionally, there are proposals for space-based instruments with all-sky imaging capabilities, such as the Orbiting Low Frequency Array. Such telescopes produce observations with three-dimensional visibility distributions and curved image domains. In most work to date, the visibility distribution has been converted to a planar form to compute the brightness map using a two-dimensional Fourier transform. The celestial sphere is faceted in order to counter pixel distortion at wide angles, with each such facet requiring a unique planar form of the visibility distribution. Under the above conditions, the computational and storage complexities of this approach can become excessive. On the other hand, when using the direct Fourier transform approach, which maintains the three-dimensional shapes of the visibility distribution and celestial sphere, the non-coplanar visibility component requires no special attention. Furthermore, as the celestial samples are placed directly on the curved surface of the celestial sphere, pixel distortion at wide angles is avoided. In this paper, a number of examples illustrate that under these conditions (very long baselines and very wide fields of view) the costs of the direct Fourier transform may be comparable to (or even lower than) methods that utilise the two-dimensional fast Fourier transform.

  15. Cross-validation of two commercial methods for volumetric high-resolution dose reconstruction on a phantom for non-coplanar VMAT beams

    International Nuclear Information System (INIS)

    Feygelman, Vladimir; Stambaugh, Cassandra; Opp, Daniel; Zhang, Geoffrey; Moros, Eduardo G.; Nelms, Benjamin E.

    2014-01-01

    Background and purpose: Delta 4 (ScandiDos AB, Uppsala, Sweden) and ArcCHECK with 3DVH software (Sun Nuclear Corp., Melbourne, FL, USA) are commercial quasi-three-dimensional diode dosimetry arrays capable of volumetric measurement-guided dose reconstruction. A method to reconstruct dose for non-coplanar VMAT beams with 3DVH is described. The Delta 4 3D dose reconstruction on its own phantom for VMAT delivery has not been thoroughly evaluated previously, and we do so by comparison with 3DVH. Materials and methods: Reconstructed volumetric doses for VMAT plans delivered with different table angles were compared between the Delta 4 and 3DVH using gamma analysis. Results: The average γ (2% local dose-error normalization/2mm) passing rate comparing the directly measured Delta 4 diode dose with 3DVH was 98.2 ± 1.6% (1SD). The average passing rate for the full volumetric comparison of the reconstructed doses on a homogeneous cylindrical phantom was 95.6 ± 1.5%. No dependence on the table angle was observed. Conclusions: Modified 3DVH algorithm is capable of 3D VMAT dose reconstruction on an arbitrary volume for the full range of table angles. Our comparison results between different dosimeters make a compelling case for the use of electronic arrays with high-resolution 3D dose reconstruction as primary means of evaluating spatial dose distributions during IMRT/VMAT verification

  16. Parallel Adaptive Mesh Refinement for High-Order Finite-Volume Schemes in Computational Fluid Dynamics

    Science.gov (United States)

    Schwing, Alan Michael

    For computational fluid dynamics, the governing equations are solved on a discretized domain of nodes, faces, and cells. The quality of the grid or mesh can be a driving source for error in the results. While refinement studies can help guide the creation of a mesh, grid quality is largely determined by user expertise and understanding of the flow physics. Adaptive mesh refinement is a technique for enriching the mesh during a simulation based on metrics for error, impact on important parameters, or location of important flow features. This can offload from the user some of the difficult and ambiguous decisions necessary when discretizing the domain. This work explores the implementation of adaptive mesh refinement in an implicit, unstructured, finite-volume solver. Consideration is made for applying modern computational techniques in the presence of hanging nodes and refined cells. The approach is developed to be independent of the flow solver in order to provide a path for augmenting existing codes. It is designed to be applicable for unsteady simulations and refinement and coarsening of the grid does not impact the conservatism of the underlying numerics. The effect on high-order numerical fluxes of fourth- and sixth-order are explored. Provided the criteria for refinement is appropriately selected, solutions obtained using adapted meshes have no additional error when compared to results obtained on traditional, unadapted meshes. In order to leverage large-scale computational resources common today, the methods are parallelized using MPI. Parallel performance is considered for several test problems in order to assess scalability of both adapted and unadapted grids. Dynamic repartitioning of the mesh during refinement is crucial for load balancing an evolving grid. Development of the methods outlined here depend on a dual-memory approach that is described in detail. Validation of the solver developed here against a number of motivating problems shows favorable

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. 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...

  5. Anterior six arms prolene mesh for high stage vaginal prolapse: five years follow-up

    Directory of Open Access Journals (Sweden)

    Luis Gustavo M. de Toledo

    Full Text Available ABSTRACT Introduction In high stage vaginal prolapse, recurrence risk patients, anterior and apical defects need to be addressed in the same procedure. The pre-molded commercial mesh kits are expensive and not always available. Alternative effective and safe treatment ways, with lower costs are desirable. Objective To present long term follow-up of patients treated with a homemade mesh shape to correct high stage prolapses. Materials and Methods We describe prospectively 18 patients with anterior and apical vaginal prolapses, stages III and IV, repaired using this specific design of mesh. All patients were submitted to pre-operative clinical evaluation and urodynamics. Prolapse was classified using the pelvic organ prolapse quantification (POP-Q. Intervention Prolapse surgery, using a six arms prolene mesh, through a single anterior vaginal incision. Outcome Measurements: POP-Q, patients satisfaction, descriptive statistical analysis. Results Between February 2009 and Oct 2010, 18 consecutive women underwent the above-mentioned surgery. Mean age was 68 years. At a mean follow-up of .,4 years (5 to 5.8 years, 16 (89% patients were continent, mean Ba point came from +4.7cm to - 2.5cm, mean C point from +2.8cm to -6.6cm and mean Bp point from +1.3 to -1.7cm. There were two (11% objective failures, but all the patients were considered success subjectively. There were two cases of mesh vaginal extrusion. Conclusions The homemade six arms prolene mesh allows concomitant correction of anterior and apical prolapses, through a single anterior vaginal incision, being an effective, safe and affordable treatment option when mesh is needed.

  6. An Approach to Quad Meshing Based On Cross Valued Maps and the Ginzburg-Landau Theory

    Energy Technology Data Exchange (ETDEWEB)

    Viertel, Ryan [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Mathematics; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Osting, Braxton [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Mathematics

    2017-08-01

    A generalization of vector fields, referred to as N-direction fields or cross fields when N=4, has been recently introduced and studied for geometry processing, with applications in quadrilateral (quad) meshing, texture mapping, and parameterization. We make the observation that cross field design for two-dimensional quad meshing is related to the well-known Ginzburg-Landau problem from mathematical physics. This identification yields a variety of theoretical tools for efficiently computing boundary-aligned quad meshes, with provable guarantees on the resulting mesh, for example, the number of mesh defects and bounds on the defect locations. The procedure for generating the quad mesh is to (i) find a complex-valued "representation" field that minimizes the Dirichlet energy subject to a boundary constraint, (ii) convert the representation field into a boundary-aligned, smooth cross field, (iii) use separatrices of the cross field to partition the domain into four sided regions, and (iv) mesh each of these four-sided regions using standard techniques. Under certain assumptions on the geometry of the domain, we prove that this procedure can be used to produce a cross field whose separatrices partition the domain into four sided regions. To solve the energy minimization problem for the representation field, we use an extension of the Merriman-Bence-Osher (MBO) threshold dynamics method, originally conceived as an algorithm to simulate motion by mean curvature, to minimize the Ginzburg-Landau energy for the optimal representation field. Lastly, we demonstrate the method on a variety of test domains.

  7. Abdominal wall hernia repair with a composite ePTFE/polypropylene mesh: clinical outcome and quality of life in 152 patients

    DEFF Research Database (Denmark)

    Iversen, E; Lykke, Anna; Hensler, M

    2010-01-01

    No consensus has yet been reached regarding the optimal mesh for the repair of small ventral hernias. A composite polytetrafluoroethylene/polypropylene mesh (Ventralex(®)) is designed for this purpose, and this paper reports its use in a larger series of patients....

  8. 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

  9. Meshing Force of Misaligned Spline Coupling and the Influence on Rotor System

    Directory of Open Access Journals (Sweden)

    Guang Zhao

    2008-01-01

    Full Text Available Meshing force of misaligned spline coupling is derived, dynamic equation of rotor-spline coupling system is established based on finite element analysis, the influence of meshing force on rotor-spline coupling system is simulated by numerical integral method. According to the theoretical analysis, meshing force of spline coupling is related to coupling parameters, misalignment, transmitting torque, static misalignment, dynamic vibration displacement, and so on. The meshing force increases nonlinearly with increasing the spline thickness and static misalignment or decreasing alignment meshing distance (AMD. Stiffness of coupling relates to dynamic vibration displacement, and static misalignment is not a constant. Dynamic behaviors of rotor-spline coupling system reveal the following: 1X-rotating speed is the main response frequency of system when there is no misalignment; while 2X-rotating speed appears when misalignment is present. Moreover, when misalignment increases, vibration of the system gets intricate; shaft orbit departs from origin, and magnitudes of all frequencies increase. Research results can provide important criterions on both optimization design of spline coupling and trouble shooting of rotor systems.

  10. Dynamic mesh adaptation for front evolution using discontinuous Galerkin based weighted condition number relaxation

    International Nuclear Information System (INIS)

    Greene, Patrick T.; Schofield, Samuel P.; Nourgaliev, Robert

    2017-01-01

    A new mesh smoothing method designed to cluster cells near a dynamically evolving interface is presented. The method is based on weighted condition number mesh relaxation with the weight function 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 fields, such as a volume fraction or index function, is provided. Results show that the low-order level set works equally well as the actual level set for mesh smoothing. Meshes generated for a number of interface geometries are presented, including cases with multiple level sets. Lastly, dynamic cases with moving interfaces show the new method is capable of maintaining a desired resolution near the interface with an acceptable number of relaxation iterations per time step, which demonstrates the method's potential to be used as a mesh relaxer for arbitrary Lagrangian Eulerian (ALE) methods.

  11. 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

  12. Unstructured Mesh Movement and Viscous Mesh Generation for CFD-Based Design Optimization, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovations proposed by ResearchSouth are: 1) a robust method to automatically insert high quality anisotropic prismatic (viscous boundary layer) cells into any...

  13. Network Coding to Enhance Standard Routing Protocols in Wireless Mesh Networks

    DEFF Research Database (Denmark)

    Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2013-01-01

    This paper introduces a design and simulation of a locally optimized network coding protocol, called PlayNCool, for wireless mesh networks. PlayN-Cool is easy to implement and compatible with existing routing protocols and devices. This allows the system to gain from network coding capabilities i...

  14. Numerical form-finding method for large mesh reflectors with elastic rim trusses

    Science.gov (United States)

    Yang, Dongwu; Zhang, Yiqun; Li, Peng; Du, Jingli

    2018-06-01

    Traditional methods for designing a mesh reflector usually treat the rim truss as rigid. Due to large aperture, light weight and high accuracy requirements on spaceborne reflectors, the rim truss deformation is indeed not negligible. In order to design a cable net with asymmetric boundaries for the front and rear nets, a cable-net form-finding method is firstly introduced. Then, the form-finding method is embedded into an iterative approach for designing a mesh reflector considering the elasticity of the supporting rim truss. By iterations on form-findings of the cable-net based on the updated boundary conditions due to the rim truss deformation, a mesh reflector with a fairly uniform tension distribution in its equilibrium state could be finally designed. Applications on offset mesh reflectors with both circular and elliptical rim trusses are illustrated. The numerical results show the effectiveness of the proposed approach and that a circular rim truss is more stable than an elliptical rim truss.

  15. 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

  16. Adaptive upscaling with the dual mesh method

    Energy Technology Data Exchange (ETDEWEB)

    Guerillot, D.; Verdiere, S.

    1997-08-01

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

  17. Variational mesh segmentation via quadric surface fitting

    KAUST Repository

    Yan, Dongming

    2012-11-01

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

  18. Variational mesh segmentation via quadric surface fitting

    KAUST Repository

    Yan, Dongming; Wang, Wen Ping; Liu, Yang; Yang, Zhouwang

    2012-01-01

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

  19. Meshed split skin graft for extensive vitiligo

    Directory of Open Access Journals (Sweden)

    Srinivas C

    2004-05-01

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

  20. ABOUT ESTIMATION OF THE OPTIMAL PARAMETERS OF MESH IN FISHING GEAR FOR FISHERY IN UKRAINE

    Directory of Open Access Journals (Sweden)

    A. Chuklin

    2013-06-01

    Full Text Available The analysis of biometric exterior indicators of haarder (Liza haematocheilus in the Azov Sea is given and by example of use of these indicators the calculations for optimization of the parameters of mesh in fishing gear for fish catching in the Ukraine is complete. The calculations show that the minimum mesh size which provides selective catch capacity concerning haarder of commercial measure (more than 38 cm should be increased in size from 30 mm to 40 mm. In this case, the probability to continue catching of juveniles from 26.8 cm to 38 cm remains, but its share will be significantly less than in case of using adopted now mesh size of 30 mm. The proposed method is recommended for engineering and biological calculations for the design of new gear and improvement of commercial fishing regulations in order to optimize and improve the effectiveness of management of fish stocks.

  1. hp-version discontinuous Galerkin methods on polygonal and polyhedral meshes

    CERN Document Server

    Cangiani, Andrea; Georgoulis, Emmanuil H; Houston, Paul

    2017-01-01

    Over the last few decades discontinuous Galerkin finite element methods (DGFEMs) have been witnessed tremendous interest as a computational framework for the numerical solution of partial differential equations. Their success is due to their extreme versatility in the design of the underlying meshes and local basis functions, while retaining key features of both (classical) finite element and finite volume methods. Somewhat surprisingly, DGFEMs on general tessellations consisting of polygonal (in 2D) or polyhedral (in 3D) element shapes have received little attention within the literature, despite the potential computational advantages. This volume introduces the basic principles of hp-version (i.e., locally varying mesh-size and polynomial order) DGFEMs over meshes consisting of polygonal or polyhedral element shapes, presents their error analysis, and includes an extensive collection of numerical experiments. The extreme flexibility provided by the locally variable elemen t-shapes, element-sizes, and elemen...

  2. Energy-efficient wireless mesh infrastructures

    OpenAIRE

    Al-Hazmi, Y.; de Meer, Hermann; Hummel, Karin Anna; Meyer, Harald; Meo, Michela; Remondo Bueno, David

    2011-01-01

    The Internet comprises access segments with wired and wireless technologies. In the future, we can expect wireless mesh infrastructures (WMIs) to proliferate in this context. Due to the relatively low energy efficiency of wireless transmission, as compared to wired transmission, energy consumption of WMIs can represent a significant part of the energy consumption of the Internet as a whole. We explore different approaches to reduce energy consumption in WMIs, taking into accoun...

  3. MESHREF, Finite Elements Mesh Combination with Renumbering

    International Nuclear Information System (INIS)

    1973-01-01

    1 - Nature of physical problem solved: The program can assemble different meshes stored on tape or cards. Renumbering is performed in order to keep band width low. Voids and/ or local refinement are possible. 2 - Method of solution: Topology and geometry are read according to input specifications. Abundant nodes and elements are eliminated. The new topology and geometry are stored on tape. 3 - Restrictions on the complexity of the problem: Maximum number of nodes = 2000. Maximum number of elements = 1500

  4. Symmetries and the coarse-mesh method

    International Nuclear Information System (INIS)

    Makai, M.

    1980-10-01

    This report approaches the basic problem of the coarse-mesh method from a new side. Group theory is used for the determination of the space dependency of the flux. The result is a method called ANANAS after the analytic-analytic solution. This method was tested on two benchmark problems: one given by Melice and the IAEA benchmark. The ANANAS program is an experimental one. The method was intended for use in hexagonal geometry. (Auth.)

  5. Wireless experiments on a Motorola mesh testbed.

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

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

  6. Surface micromachined counter-meshing gears discrimination device

    International Nuclear Information System (INIS)

    Polosky, M.A.; Garcia, E.J.; Allen, J.J.

    1998-01-01

    This paper discusses the design, fabrication and testing of a surface micromachined Counter-Meshing Gears (CMG) discrimination device which functions as a mechanically coded lock, A 24 bit code is input to unlock the device. Once unlocked, the device provides a path for an energy or information signal to pass through the device. The device is designed to immediately lock up if any portion of the 24 bit code is incorrect. The motivation for the development of this device is based on occurrences referred to as High Consequence Events, A High Consequence Event is an event where an inadvertent operation of a system could result in the catastrophic loss of life, property, or damage to the environment

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Cu mesh for flexible transparent conductive electrodes.

    Science.gov (United States)

    Kim, Won-Kyung; Lee, Seunghun; Hee Lee, Duck; Hee Park, In; Seong Bae, Jong; Woo Lee, Tae; Kim, Ji-Young; Hun Park, Ji; Chan Cho, Yong; Ryong Cho, Chae; Jeong, Se-Young

    2015-06-03

    Copper electrodes with a micromesh/nanomesh structure were fabricated on a polyimide substrate using UV lithography and wet etching to produce flexible transparent conducting electrodes (TCEs). Well-defined mesh electrodes were realized through the use of high-quality Cu thin films. The films were fabricated using radio-frequency (RF) sputtering with a single-crystal Cu target--a simple but innovative approach that overcame the low oxidation resistance of ordinary Cu. Hybrid Cu mesh electrodes were fabricated by adding a capping layer of either ZnO or Al-doped ZnO. The sheet resistance and the transmittance of the electrode with an Al-doped ZnO capping layer were 6.197 ohm/sq and 90.657%, respectively, and the figure of merit was 60.502 × 10(-3)/ohm, which remained relatively unchanged after thermal annealing at 200 °C and 1,000 cycles of bending. This fabrication technique enables the mass production of large-area flexible TCEs, and the stability and high performance of Cu mesh hybrid electrodes in harsh environments suggests they have strong potential for application in smart displays and solar cells.

  12. 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.

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

    Science.gov (United States)

    Mao, Yuqing; Lu, Zhiyong

    2017-04-17

    MeSH indexing is the task of assigning relevant MeSH terms based on a manual reading of scholarly publications by human indexers. The task is highly important for improving literature retrieval and many other scientific investigations in biomedical research. Unfortunately, given its manual nature, the process of MeSH indexing is both time-consuming (new articles are not immediately indexed until 2 or 3 months later) and costly (approximately ten dollars per article). In response, automatic indexing by computers has been previously proposed and attempted but remains challenging. In order to advance the state of the art in automatic MeSH indexing, a community-wide shared task called BioASQ was recently organized. We propose MeSH Now, an integrated approach that first uses multiple strategies to generate a combined list of candidate MeSH terms for a target article. Through a novel learning-to-rank framework, MeSH Now then ranks the list of candidate terms based on their relevance to the target article. Finally, MeSH Now selects the highest-ranked MeSH terms via a post-processing module. We assessed MeSH Now on two separate benchmarking datasets using traditional precision, recall and F 1 -score metrics. In both evaluations, MeSH Now consistently achieved over 0.60 in F-score, ranging from 0.610 to 0.612. Furthermore, additional experiments show that MeSH Now can be optimized by parallel computing in order to process MEDLINE documents on a large scale. We conclude that MeSH Now is a robust approach with state-of-the-art performance for automatic MeSH indexing and that MeSH Now is capable of processing PubMed scale documents within a reasonable time frame. http://www.ncbi.nlm.nih.gov/CBBresearch/Lu/Demo/MeSHNow/ .

  14. 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.

  15. Effective Bandwidth Allocation for WiMAX Mesh Network

    Directory of Open Access Journals (Sweden)

    Hung-Chin Jang

    2010-04-01

    Full Text Available The aim of this paper is to reduce the media access delay in a WiMAX mesh network. We observe that as the number of subscriber stations (SS in a neighborhood increases, the processes of transmission opportunity (TO competition and 3- way handshake are easy to fail. This may degrade transmission efficiency and increase packet transmission delay. Besides, the minislot allocation defined in the WiMAX mesh mode may cause many lower priority services reserve earlier minislots than that of higher priority services like rtPS. This may cause great negative impact on delay-sensitive traffic. In this paper, we design a QoS classifier to enqueue packets according to different QoS service classes, present a dynamic holdoff exponent mechanism to reduce control subframe delay, and propose a Neighborhood-Based Minislot Allocation (NBMA mechanism to reduce data subframe delay. Simulations show that the proposed methodology outperforms that of IEEE 802.16 and Baye's DynExp in delay, jitter and throughput.

  16. Development and acceleration of unstructured mesh-based cfd solver

    Science.gov (United States)

    Emelyanov, V.; Karpenko, A.; Volkov, K.

    2017-06-01

    The study was undertaken as part of a larger effort to establish a common computational fluid dynamics (CFD) code for simulation of internal and external flows and involves some basic validation studies. The governing equations are solved with ¦nite volume code on unstructured meshes. The computational procedure involves reconstruction of the solution in each control volume and extrapolation of the unknowns to find the flow variables on the faces of control volume, solution of Riemann problem for each face of the control volume, and evolution of the time step. The nonlinear CFD solver works in an explicit time-marching fashion, based on a three-step Runge-Kutta stepping procedure. Convergence to a steady state is accelerated by the use of geometric technique and by the application of Jacobi preconditioning for high-speed flows, with a separate low Mach number preconditioning method for use with low-speed flows. The CFD code is implemented on graphics processing units (GPUs). Speedup of solution on GPUs with respect to solution on central processing units (CPU) is compared with the use of different meshes and different methods of distribution of input data into blocks. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.

  17. Configuring the Mesh Size, Side Taper and Wing Depth of Penaeid Trawls to Reduce Environmental Impacts

    Science.gov (United States)

    Broadhurst, Matt K.; Sterling, David J.; Millar, Russell B.

    2014-01-01

    The effects of reducing mesh size while concomitantly varying the side taper and wing depth of a generic penaeid-trawl body were investigated to improve engineering performance and minimize bycatch. Five trawl bodies (with the same codends) were tested across various environmental (e.g. depth and current) and biological (e.g. species and sizes) conditions. The first trawl body comprised 41-mm mesh and represented conventional designs (termed the ‘41 long deep-wing'), while the remaining trawl bodies were made from 32-mm mesh and differed only in their side tapers, and therefore length (i.e. 1N3B or ‘long’ and ∼28o to the tow direction vs 1N5B or ‘short’ and ∼35o) and wing depths (‘deep’–97 T vs ‘shallow’–60 T). There were incremental drag reductions (and therefore fuel savings – by up to 18 and 12% per h and ha trawled) associated with reducing twine area via either modification, and subsequently minimizing otter-board area in attempts to standardize spread. Side taper and wing depth had interactive and varied effects on species selectivity, but compared to the conventional 41 long deep-wing trawl, the 32 short shallow-wing trawl (i.e. the least twine area) reduced the total bycatch by 57% (attributed to more fish swimming forward and escaping). In most cases, all small-meshed trawls also caught more smaller school prawns Metapenaeus macleayi but to decrease this effect it should be possible to increase mesh size slightly, while still maintaining the above engineering benefits and species selectivity. The results support precisely optimizing mesh size as a precursor to any other anterior penaeid-trawl modifications designed to improve environmental performance. PMID:24911786

  18. 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

  19. Magnetic-field design of the accumulator multipole magnet

    International Nuclear Information System (INIS)

    Oleksiuk, L.

    1983-01-01

    A multiple magnet using the FFAG graded coil technique has been designed with the aid of the two dimensional magnet modelling code Poisson. Rapid design interaction in problem formulation has been achieved with a new finite element mesh generator in which mesh densities can be manipulated to overcome difficulties in mesh topologies when spanning the grid over the problem domain

  20. Dosimetric comparison between intensity-modulated with coplanar field and 3D conformal radiotherapy with noncoplanar field for postocular invasion tumor.

    Science.gov (United States)

    Wenyong, Tu; Lu, Liu; Jun, Zeng; Weidong, Yin; Yun, Li

    2010-01-01

    This study presents a dosimetric optimization effort aiming to compare noncoplanar field (NCF) on 3 dimensions conformal radiotherapy (3D-CRT) and coplanar field (CF) on intensity-modulated radiotherapy (IMRT) planning for postocular invasion tumor. We performed a planning study on the computed tomography data of 8 consecutive patients with localized postocular invasion tumor. Four fields NCF 3D-CRT in the transverse plane with gantry angles of 0-10 degrees , 30-45 degrees , 240-270 degrees , and 310-335 degrees degrees were isocentered at the center of gravity of the target volume. The geometry of the beams was determined by beam's eye view. The same constraints were prepared with between CF IMRT optimization and NCF 3D-CRT treatment. The maximum point doses (D max) for the different optic pathway structures (OPS) with NCF 3D-CRT treatment should differ in no more than 3% from those with the NCF IMRT plan. Dose-volume histograms (DVHs) were obtained for all targets and organ at risk (OAR) with both treatment techniques. Plans with NCF 3D-CRT and CF IMRT constraints on target dose in homogeneity were computed, as well as the conformity index (CI) and homogeneity index (HI) in the target volume. The PTV coverage was optimal with both NCF 3D-CRT and CF IMRT plans in the 8 tumor sites. No difference was noted between the two techniques for the average D(max) and D(min) dose. NCF 3D-CRT and CF IMRT will yield similar results on CI. However, HI was a significant difference between NCF 3D-CRT and CF IMRT plan (p 3D-CRT versus CF IMRT set-up is very slight. NCF3D-CRT is one of the treatment options for postocular invasion tumor. However, constraints for OARs are needed. 2010 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  1. Coligand-regulated assembly, fluorescence, and magnetic properties of Co(II) and Cd(II) complexes with a non-coplanar dicarboxylate

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Ling-Yun [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022 (China); Liu, Guang-Zhen, E-mail: gzliuly@126.com [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022 (China); Ma, Lu-Fang [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022 (China); Wang, Li-Ya [College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022 (China); College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang 473061 (China)

    2013-10-15

    A non-coplanar dicarboxylate ndca (H{sub 2}ndca=5-norbornene-2,3-dicarboxylic acid), combining with various dipyridyl-typed tectons, constructs six Cd(II)/Co(II) coordination polymers under hydrothermal conditions, namely [Co(ndca)(H{sub 2}O)]{sub n} (1), ([Co(ndca)(bpe)(H{sub 2}O)]·H{sub 2}O){sub n} (2), [Co(ndca)(bpa){sub 0.5}(H{sub 2}O)]{sub n} (3), [Cd(ndca)(bpe)(H{sub 2}O)]{sub n} (4), ([Cd(ndca)(bpa)(H{sub 2}O)]·0.5H{sub 2}O){sub n} (5), and ([Cd(ndca)(bpp) (H{sub 2}O)]·H{sub 2}O){sub n} (6) (bpe=1,2-di(4-pyridyl)ethylene, bpa=1,2-bi(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane). All these compounds contain various metal(II)–carboxylate motifs, including carboxylate binuclear (2, 4, 5), carboxylate chain (1, 6) and carboxylate layer (3), which are further extended by dipyridyl-typed coligands to afford a vast diversity of the structures with 2D pyknotic layers (1, 6), 2D open layer (5), 2D→3D interpenetrated networks (2,4), and 3D pillared-layer framework (3), respectively. In addition, fluorescent spectra of Cd(II) complexes and magnetic properties of Co(II) complexes are also given. - Graphical abstract: Six various cadmium(II)/cobalt(II)–organic frameworks were constructed by 5-norbornene-2,3-dicarboxylic acid and different bis(pyridine) rod-like tectons, and Cd (II) complexes exhibit blue–violet emissions, whereas Co (II) complexes show antiferromagnetic behaviours. Display Omitted.

  2. Coligand-regulated assembly, fluorescence, and magnetic properties of Co(II) and Cd(II) complexes with a non-coplanar dicarboxylate

    International Nuclear Information System (INIS)

    Xin, Ling-Yun; Liu, Guang-Zhen; Ma, Lu-Fang; Wang, Li-Ya

    2013-01-01

    A non-coplanar dicarboxylate ndca (H 2 ndca=5-norbornene-2,3-dicarboxylic acid), combining with various dipyridyl-typed tectons, constructs six Cd(II)/Co(II) coordination polymers under hydrothermal conditions, namely [Co(ndca)(H 2 O)] n (1), ([Co(ndca)(bpe)(H 2 O)]·H 2 O) n (2), [Co(ndca)(bpa) 0.5 (H 2 O)] n (3), [Cd(ndca)(bpe)(H 2 O)] n (4), ([Cd(ndca)(bpa)(H 2 O)]·0.5H 2 O) n (5), and ([Cd(ndca)(bpp) (H 2 O)]·H 2 O) n (6) (bpe=1,2-di(4-pyridyl)ethylene, bpa=1,2-bi(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane). All these compounds contain various metal(II)–carboxylate motifs, including carboxylate binuclear (2, 4, 5), carboxylate chain (1, 6) and carboxylate layer (3), which are further extended by dipyridyl-typed coligands to afford a vast diversity of the structures with 2D pyknotic layers (1, 6), 2D open layer (5), 2D→3D interpenetrated networks (2,4), and 3D pillared-layer framework (3), respectively. In addition, fluorescent spectra of Cd(II) complexes and magnetic properties of Co(II) complexes are also given. - Graphical abstract: Six various cadmium(II)/cobalt(II)–organic frameworks were constructed by 5-norbornene-2,3-dicarboxylic acid and different bis(pyridine) rod-like tectons, and Cd (II) complexes exhibit blue–violet emissions, whereas Co (II) complexes show antiferromagnetic behaviours. Display Omitted

  3. 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

  4. 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.

  5. 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

  6. 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....

  7. 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

  8. 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.

  9. Compatible discrete operator schemes on polyhedral meshes for elliptic and Stokes equations

    International Nuclear Information System (INIS)

    Bonelle, Jerome

    2014-01-01

    This thesis presents a new class of spatial discretization schemes on polyhedral meshes, called Compatible Discrete Operator (CDO) schemes and their application to elliptic and Stokes equations In CDO schemes, preserving the structural properties of the continuous equations is the leading principle to design the discrete operators. De Rham maps define the degrees of freedom according to the physical nature of fields to discretize. CDO schemes operate a clear separation between topological relations (balance equations) and constitutive relations (closure laws). Topological relations are related to discrete differential operators, and constitutive relations to discrete Hodge operators. A feature of CDO schemes is the explicit use of a second mesh, called dual mesh, to build the discrete Hodge operator. Two families of CDO schemes are considered: vertex-based schemes where the potential is located at (primal) mesh vertices, and cell-based schemes where the potential is located at dual mesh vertices (dual vertices being in one-to-one correspondence with primal cells). The CDO schemes related to these two families are presented and their convergence is analyzed. A first analysis hinges on an algebraic definition of the discrete Hodge operator and allows one to identify three key properties: symmetry, stability, and P0-consistency. A second analysis hinges on a definition of the discrete Hodge operator using reconstruction operators, and the requirements on these reconstruction operators are identified. In addition, CDO schemes provide a unified vision on a broad class of schemes proposed in the literature (finite element, finite element, mimetic schemes... ). Finally, the reliability and the efficiency of CDO schemes are assessed on various test cases and several polyhedral meshes. (author)

  10. Conjugate gradient determination of optimal plane changes for a class of three-impulse transfers between noncoplanar circular orbits

    Science.gov (United States)

    Burrows, R. R.

    1972-01-01

    A particular type of three-impulse transfer between two circular orbits is analyzed. The possibility of three plane changes is recognized, and the problem is to optimally distribute these plane changes to minimize the sum of the individual impulses. Numerical difficulties and their solution are discussed. Numerical results obtained from a conjugate gradient technique are presented for both the case where the individual plane changes are unconstrained and for the case where they are constrained. Possibly not unexpectedly, multiple minima are found. The techniques presented could be extended to the finite burn case, but primarily the contents are addressed to preliminary mission design and vehicle sizing.

  11. Construct mine environment monitoring system based on wireless mesh network

    Science.gov (United States)

    Chen, Xin; Ge, Gengyu; Liu, Yinmei; Cheng, Aimin; Wu, Jun; Fu, Jun

    2018-04-01

    The system uses wireless Mesh network as a network transmission medium, and strive to establish an effective and reliable underground environment monitoring system. The system combines wireless network technology and embedded technology to monitor the internal data collected in the mine and send it to the processing center for analysis and environmental assessment. The system can be divided into two parts: the main control network module and the data acquisition terminal, and the SPI bus technology is used for mutual communication between them. Multi-channel acquisition and control interface design Data acquisition and control terminal in the analog signal acquisition module, digital signal acquisition module, and digital signal output module. The main control network module running Linux operating system, in which the transplant SPI driver, USB card driver and AODV routing protocol. As a result, the internal data collection and reporting of the mine are realized.

  12. 3D unstructured mesh discontinuous finite element hydro

    International Nuclear Information System (INIS)

    Prasad, M.K.; Kershaw, D.S.; Shaw, M.J.

    1995-01-01

    The authors present detailed features of the ICF3D hydrodynamics code used for inertial fusion simulations. This code is intended to be a state-of-the-art upgrade of the well-known fluid code, LASNEX. ICF3D employs discontinuous finite elements on a discrete unstructured mesh consisting of a variety of 3D polyhedra including tetrahedra, prisms, and hexahedra. The authors discussed details of how the ROE-averaged second-order convection was applied on the discrete elements, and how the C++ coding interface has helped to simplify implementing the many physics and numerics modules within the code package. The author emphasized the virtues of object-oriented design in large scale projects such as ICF3D

  13. Unbiased Sampling and Meshing of Isosurfaces

    KAUST Repository

    Yan, Dongming

    2014-05-07

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

  14. Symbolic Block Decomposition In Hexahedral Mesh Generation

    Directory of Open Access Journals (Sweden)

    Andrzej Adamek

    2005-01-01

    Full Text Available Hexahedral mesh generation for three-dimensional solid objects is often done in stages. Usually an object is first subdivided into simple-shaped subregions, which then are filled withhexahedral finite elements. This article presents an automatic subdividing method of polyhedron with planar faces. The subdivision is based on medial surface, axes and nodes of a solid.The main emphasis is put on creating a topology of subregions. Obtaining such a topologyinvolves defining a graph structure OMG which contains necessary information about medialsurface topology and object topology, followed by simple symbolic processing on it.

  15. Shadowfax: Moving mesh hydrodynamical integration code

    Science.gov (United States)

    Vandenbroucke, Bert

    2016-05-01

    Shadowfax simulates galaxy evolution. Written in object-oriented modular C++, it evolves a mixture of gas, subject to the laws of hydrodynamics and gravity, and any collisionless fluid only subject to gravity, such as cold dark matter or stars. For the hydrodynamical integration, it makes use of a (co-) moving Lagrangian mesh. The code has a 2D and 3D version, contains utility programs to generate initial conditions and visualize simulation snapshots, and its input/output is compatible with a number of other simulation codes, e.g. Gadget2 (ascl:0003.001) and GIZMO (ascl:1410.003).

  16. Unbiased Sampling and Meshing of Isosurfaces

    KAUST Repository

    Yan, Dongming; Wallner, Johannes; Wonka, Peter

    2014-01-01

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

  17. 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...

  18. 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

  19. 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,...

  20. 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)

  1. 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.

  2. 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...

  3. 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...

  4. Automated quadrilateral mesh generation for digital image structures

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Preliminary Single-Phase Mixing Test using Wire Mesh System in a wire-wrapped 37-rod Bundle

    International Nuclear Information System (INIS)

    Bae, Hwang; Kim, Hyungmo; Lee, Dong Won; Choi, Hae Seob; Choi, Sun Rock; Chang, Seokkyu; Kim, Seok; Euh, Dongjin; Lee, Hyeongyeon

    2014-01-01

    In this paper, preliminary tests of the wire-mesh sensor are introduced before measuring of mixing coefficient in the wire-wrapped 37-pin fuel assembly for a sodium-cooled fast reactor. Through this preliminary test, it was confirmed that city water can be used as a tracer for demineralized water as a base. A simple test was performed to evaluate the characteristics of a wire mesh with of a short pipe shape. The conductivity of de-mineralized water and city water is linearly increased for the limited temperature ranges as the temperature is increased. The reliability of the wire mesh sensor was estimated based on the averages and standard deviations of the plane image using the cross points. A wire mesh sensor is suitable to apply to a single-phase flow measurement for a mixture with de-mineralized water and city water. A wire mesh sensor and system have been traditionally used to measure the void fraction of a two-phase flow field with gas and liquid. Recently, Ylonen et al. successfully designed and commissioned a measurement system for a single-phase flow using a wire mesh sensor

  14. Mesh-based parallel code coupling interface

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-04-01

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

  15. 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...

  16. Dosimetric Comparison Between Intensity-Modulated with Coplanar Field and 3D Conformal Radiotherapy with Noncoplanar Field for Postocular Invasion Tumor

    International Nuclear Information System (INIS)

    Tu Wenyong; Liu Lu; Zeng Jun; Yin Weidong; Li Yun

    2010-01-01

    This study presents a dosimetric optimization effort aiming to compare noncoplanar field (NCF) on 3 dimensions conformal radiotherapy (3D-CRT) and coplanar field (CF) on intensity-modulated radiotherapy (IMRT) planning for postocular invasion tumor. We performed a planning study on the computed tomography data of 8 consecutive patients with localized postocular invasion tumor. Four fields NCF 3D-CRT in the transverse plane with gantry angles of 0-10 deg., 30-45 deg., 240-270 deg., and 310-335 deg. degrees were isocentered at the center of gravity of the target volume. The geometry of the beams was determined by beam's eye view. The same constraints were prepared with between CF IMRT optimization and NCF 3D-CRT treatment. The maximum point doses (D max) for the different optic pathway structures (OPS) with NCF 3D-CRT treatment should differ in no more than 3% from those with the NCF IMRT plan. Dose-volume histograms (DVHs) were obtained for all targets and organ at risk (OAR) with both treatment techniques. Plans with NCF 3D-CRT and CF IMRT constraints on target dose in homogeneity were computed, as well as the conformity index (CI) and homogeneity index (HI) in the target volume. The PTV coverage was optimal with both NCF 3D-CRT and CF IMRT plans in the 8 tumor sites. No difference was noted between the two techniques for the average D max and D min dose. NCF 3D-CRT and CF IMRT will yield similar results on CI. However, HI was a significant difference between NCF 3D-CRT and CF IMRT plan (p < 0.001). Physical endpoints for target showed the mean target dose to be low in the CF IMRT plan, caused by a large target dose in homogeneity (p < 0.001). The impact of NCF 3D-CRT versus CF IMRT set-up is very slight. NCF3D-CRT is one of the treatment options for postocular invasion tumor. However, constraints for OARs are needed.

  17. Adaptive mesh refinement and adjoint methods in geophysics simulations

    Science.gov (United States)

    Burstedde, Carsten

    2013-04-01

    It is an ongoing challenge to increase the resolution that can be achieved by numerical geophysics simulations. This applies to considering sub-kilometer mesh spacings in global-scale mantle convection simulations as well as to using frequencies up to 1 Hz in seismic wave propagation simulations. One central issue is the numerical cost, since for three-dimensional space discretizations, possibly combined with time stepping schemes, a doubling of resolution can lead to an increase in storage requirements and run time by factors between 8 and 16. A related challenge lies in the fact that an increase in resolution also increases the dimensionality of the model space that is needed to fully parametrize the physical properties of the simulated object (a.k.a. earth). Systems that exhibit a multiscale structure in space are candidates for employing adaptive mesh refinement, which varies the resolution locally. An example that we found well suited is the mantle, where plate boundaries and fault zones require a resolution on the km scale, while deeper area can be treated with 50 or 100 km mesh spacings. This approach effectively reduces the number of computational variables by several orders of magnitude. While in this case it is possible to derive the local adaptation pattern from known physical parameters, it is often unclear what are the most suitable criteria for adaptation. We will present the goal-oriented error estimation procedure, where such criteria are derived from an objective functional that represents the observables to be computed most accurately. Even though this approach is well studied, it is rarely used in the geophysics community. A related strategy to make finer resolution manageable is to design methods that automate the inference of model parameters. Tweaking more than a handful of numbers and judging the quality of the simulation by adhoc comparisons to known facts and observations is a tedious task and fundamentally limited by the turnaround times

  18. 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.

  19. Orbital Reconstruction: Patient-Specific Orbital Floor Reconstruction Using a Mirroring Technique and a Customized Titanium Mesh.

    Science.gov (United States)

    Tarsitano, Achille; Badiali, Giovanni; Pizzigallo, Angelo; Marchetti, Claudio

    2016-10-01

    Enophthalmos is a severe complication of primary reconstruction of orbital floor fractures. The goal of secondary reconstruction procedures is to restore symmetrical globe positions to recover function and aesthetics. The authors propose a new method of orbital floor reconstruction using a mirroring technique and a customized titanium mesh, printed using a direct metal laser-sintering method. This reconstructive protocol involves 4 steps: mirroring of the healthy orbit at the affected site, virtual design of a patient-specific orbital floor mesh, CAM procedures for direct laser-sintering of the customized titanium mesh, and surgical insertion of the device. Using a computed tomography data set, the normal, uninjured side of the craniofacial skeleton was reflected onto the contralateral injured side, and a reconstructive orbital floor mesh was designed virtually on the mirrored orbital bone surface. The solid-to-layer files of the mesh were then manufactured using direct metal laser sintering, which resolves the shaping and bending biases inherent in the indirect method. An intraoperative navigation system ensured accuracy of the entire procedure. Clinical outcomes were assessed using 3dMD photogrammetry and computed tomography data in 7 treated patients. The technique described here appears to be a viable method to correct complex orbital floor defects needing delayed reconstruction. This study represents the first step in the development of a wider experimental protocol for orbital floor reconstruction using computer-assisted design-computer-assisted manufacturing technology.

  20. Design Criteria for Wireless Mesh Communications in Underground Coal Mines

    OpenAIRE

    Griffin, Kenneth Reed

    2009-01-01

    The Mine Improvement and New Emergency Response (MINER) Act of 2006 was enacted in response to several coal mining accidents that occurred in the beginning of 2006. The MINER Act does not just require underground mines to integrate wireless communication and tracking systems, but aims to overall enhance health and safety in mining at both surface and underground operations. In 2006, the underground communication technologies available to the mining industry had inherent problems that limited ...

  1. Design and Characterization of Vertical Mesh Capacitors in Standard CMOS

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais

    2001-01-01

    This paper shows how good RF capacitors can be made in a standard digital CMOS process. The capacitors which are also well suited for binary weighted switched capacitor banks show very good RF performance: Q-values of 57 at 4.0 GHz, a density of 0.27 fF/μ2, 2.2 μm wide shielded unit capacitors, 6...

  2. Mediating Dynamic Supply Chain Formation by Collaborative Single Machine Earliness/Tardiness Agents in Supply Mesh

    Directory of Open Access Journals (Sweden)

    Hang Yang

    2014-01-01

    Full Text Available Nowadays, a trend of forming dynamic supply chains with different trading partners over different e-marketplaces has emerged. These supply chains, which are called “supply mesh,” generally refer to heterogeneous electronic marketplaces in which dynamic supply chains, as per project (often make-to-order, are formed across different parties. Conceptually, in a supply mesh a dynamic supply chain is formed vertically, mediating several companies for a project. Companies that are on the same level horizontally are either competitors or cohorts. A complex scenario such as this makes it challenging to find the right group of members for a dynamic supply chain. Earlier on, a multiagent model called the collaborative single machine earliness/tardiness (CSET model was proposed for the optimal formation of make-to-order supply chains. This paper contributes the particular agent designs, for enabling the mediation of CSET in a supply mesh, and the possibilities are discussed. It is demonstrated via a computer simulation, based on samples from the U.S. textile industry, that by using intelligent agents under the CSET model it is possible to automatically find an ideal group of trading partners from a supply mesh.

  3. Shear strength of reinforced concrete beams strengthened by P.B.O. fiber mesh under loading

    Directory of Open Access Journals (Sweden)

    Blikharskyy Zinoviy

    2017-01-01

    Full Text Available This article presents experimental study of sheer strength of reinforced concrete beams without transverse steel reinforcement, which strengthened by composite materials. The feature of tests is that the beams’ strengthening is made under simultaneous action of loading. The research program involves a series of test beams with size 2100 × 200 × 100 mm and which contains control sample and three reinforced samples by reinforcing FRCM system. FRCM system consisting of two components: mineral mortar based on modified cement Ruredil X Mesh M750 and reinforcing P.B.O. fiber mesh Ruredil X Mesh Gold (Italy. The strength research of test samples was carried out with the shear distance to effective depth ratio a/d = 2. The strengthening loading levels were selected at 0.0, 0.3, 0.5 from shear strength of non strengthened control sample. As a result of experimental studies we found that during strengthening design the inclined cross section of beams we should take into account the existing level of loading. Using the strengthening system Ruredil X Mesh Gold the strengthening effect is reduced at 2.8 to 2.9 times while the existing level of loading increase from 0 to 50%.

  4. Improved mesh based photon sampling techniques for neutron activation analysis

    International Nuclear Information System (INIS)

    Relson, E.; Wilson, P. P. H.; Biondo, E. D.

    2013-01-01

    The design of fusion power systems requires analysis of neutron activation of large, complex volumes, and the resulting particles emitted from these volumes. Structured mesh-based discretization of these problems allows for improved modeling in these activation analysis problems. Finer discretization of these problems results in large computational costs, which drives the investigation of more efficient methods. Within an ad hoc subroutine of the Monte Carlo transport code MCNP, we implement sampling of voxels and photon energies for volumetric sources using the alias method. The alias method enables efficient sampling of a discrete probability distribution, and operates in 0(1) time, whereas the simpler direct discrete method requires 0(log(n)) time. By using the alias method, voxel sampling becomes a viable alternative to sampling space with the 0(1) approach of uniformly sampling the problem volume. Additionally, with voxel sampling it is straightforward to introduce biasing of volumetric sources, and we implement this biasing of voxels as an additional variance reduction technique that can be applied. We verify our implementation and compare the alias method, with and without biasing, to direct discrete sampling of voxels, and to uniform sampling. We study the behavior of source biasing in a second set of tests and find trends between improvements and source shape, material, and material density. Overall, however, the magnitude of improvements from source biasing appears to be limited. Future work will benefit from the implementation of efficient voxel sampling - particularly with conformal unstructured meshes where the uniform sampling approach cannot be applied. (authors)

  5. 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 ...

  6. 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.

  7. 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...

  8. 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

  9. 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.

  10. 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 ...

  11. 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.

  12. 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...

  13. 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…

  14. 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.

  15. 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....

  16. 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.

  17. 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)

  18. 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.

  19. COSMOLOGICAL ADAPTIVE MESH REFINEMENT MAGNETOHYDRODYNAMICS WITH ENZO

    International Nuclear Information System (INIS)

    Collins, David C.; Xu Hao; Norman, Michael L.; Li Hui; Li Shengtai

    2010-01-01

    In this work, we present EnzoMHD, the extension of the cosmological code Enzo to include the effects of magnetic fields through the ideal magnetohydrodynamics approximation. We use a higher order Godunov method for the computation of interface fluxes. We use two constrained transport methods to compute the electric field from those interface fluxes, which simultaneously advances the induction equation and maintains the divergence of the magnetic field. A second-order divergence-free reconstruction technique is used to interpolate the magnetic fields in the block-structured adaptive mesh refinement framework already extant in Enzo. This reconstruction also preserves the divergence of the magnetic field to machine precision. We use operator splitting to include gravity and cosmological expansion. We then present a series of cosmological and non-cosmological test problems to demonstrate the quality of solution resulting from this combination of solvers.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. A Full Mesh ATCA-based General Purpose Data Processing Board: Pulsar II

    CERN Document Server

    Olsen, J; Okumura, Y

    2014-01-01

    High luminosity conditions at the LHC pose many unique challenges for potential silicon based track trigger systems. Among those challenges is data formatting, where hits from thousands of silicon modules must first be shared and organized into overlapping trigger towers. Other challenges exist for Level-1 track triggers, where many parallel data paths may be used for 5 high speed time multiplexed data transfers. Communication between processing nodes requires high bandwidth, low latency, and flexible real time data sharing, for which a full mesh backplane is a natural fit. A custom full mesh enabled ATCA board called the Pulsar II has been designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth board- to-board communication channels while keeping the design as simple as possible.

  6. 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

  7. 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.

  8. 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.

  9. QMESH RENUM QPLOT, Mesh Generator on 2-D Bodies for Finite Element Method Analysis, with Plot Utility

    International Nuclear Information System (INIS)

    Jones, R.E.; Schkade, A.F.; Eyberger, L.R.

    1991-01-01

    1 - Description of problem or function: A set of five programs which make up a self-organising mesh generation package. QMESH generates meshes having quadrilateral elements on arbitrarily-shaped, two-dimensional (planar or axisymmetric) bodies. It is designed for use with two-dimensional finite element analysis applications. A flexible hierarchical input scheme is used to describe bodies to QMESH as collections of regions. A mesh for each region is developed independently, with the final assembly and bandwidth minimization performed by the independent program, RENUM or RENUM8. RENUM is applied when four-node elements are desired. Eight-node elements (with mid-side nodes) may be obtained with RENUM8., QPLOT and QPLOT8 are plot programs for meshes generated by the QMESH/RENUM and QMESH/RENUM8 program pairs, respectively. QPLOT and QPLOT8 automatically section the mesh into appropriately-sized sections for legible display of node and element numbers. An overall plot showing the position of the selected plot areas is produced. 2 - Method of solution: The mesh generating process for each individual region begins with the installation of an initial mesh which is a transformation of a regular grid on the unit square. The dimensions and orientation of the initial mesh may be defined by the user or, optionally, may be chosen by QMESH. Various smoothing algorithms may be applied to the initial mesh. Then, the mesh may be 'restructured' using an iterative scheme involving 'element pair restructuring', 'acute element deletion', and smoothing. In element pair restructuring, the interface side between two elements is removed and placed between two different nodes belonging to the pair of elements, provided that the change produces an overall improvement in the shapes of the two elements. In acute element deletion, an element having one diagonal much shorter than the other is deleted by collapsing the short diagonal to zero length The exact order in which restructuring, element

  10. Synthesis of Gold Nanoparticle-Embedded Silver Cubic Mesh Nanostructures Using AgCl Nanocubes for Plasmonic Photocatalysis.

    Science.gov (United States)

    Joo, Jang Ho; Kim, Byung-Ho; Lee, Jae-Seung

    2017-11-01

    A novel room-temperature aqueous synthesis for gold nanoparticle-embedded silver cubic mesh nanostructures using AgCl templates via a template-assisted coreduction method is developed. The cubic AgCl templates are coreduced in the presence of AuCl 4 - and Ag + , resulting in the reduction of AuCl 4 - into gold nanoparticles on the outer region of AgCl templates, followed by the reduction of AgCl and Ag + into silver cubic mesh nanostructures. Removal of the template clearly demonstrates the delicately designed silver mesh nanostructures embedded with gold nanoparticles. The synthetic mechanism, structural properties, and surface functionalization are spectroscopically investigated. The plasmonic photocatalysis of the cubic mesh nanostructures for the degradation of organic pollutants and removal of highly toxic metal ions is investigated; the photocatalytic activity of the cubic mesh nanostructures is superior to those of conventional TiO 2 catalysts and they are catalytically functional even in natural water, owing to their high surface area and excellent chemical stability. The synthetic development presented in this study can be exploited for the highly elaborate, yet, facile design of nanomaterials with outstanding properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fuel-steel mixing and radial mesh effects in power excursion simulations

    International Nuclear Information System (INIS)

    Chen, X.-N.; Rineiski, A.; Gabrielli, F.; Andriolo, L.; Vezzoni, B.; Li, R.; Maschek, W.; Kiefhaber, E.

    2016-01-01

    Highlights: • Fuel-steel mixing and radial mesh effects are significant on power excursion. • The earliest power peak is reduced and retarded by these two effects. • Unprotected loss of coolant transients in ESFR core are calculated. - Abstract: This paper deals with SIMMER-III once-through simulations of the earliest power excursion initiated by an unprotected loss of flow (ULOF) in the Working Horse design of the European Sodium Cooled Fast Reactor (ESFR). Since the sodium void effect is strictly positive in this core and dominant in the transient, a power excursion is initiated by sodium boiling in the ULOF case. Two major effects, namely (1) reactivity effects due to fuel-steel mixing after melting and (2) the radial mesh size, which were not considered originally in SIMMER simulations for ESFR, are studied. The first effect concerns the reactivity difference between the heterogeneous fuel/clad/wrapper configuration and the homogeneous mixture of steel and fuel. The full core homogenization (due to melting) effect is −2 $, though a smaller effect takes place in case of partial core melting. The second effect is due to the SIMMER sub-assembly (SA) coarse mesh treatment, where a simultaneous sodium boiling onset in all SAs belonging to one ring leads to an overestimated reactivity ramp. For investigating the influence of fuel/steel mixing effects, a lumped “homogenization” reactivity feedback has been introduced, being proportional to the molten steel mass. For improving the coarse mesh treatment, we employ finer radial meshes to take the subchannel effects into account, where the side and interior channels have different coolant velocities and temperatures. The simulation results show that these two effects have significant impacts on the earliest power excursion after the sodium boiling.

  12. Throughput vs. Delay in Lossy Wireless Mesh Networks with Random Linear Network Coding

    OpenAIRE

    Hundebøll, Martin; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2014-01-01

    This work proposes a new protocol applying on–the–fly random linear network coding in wireless mesh net-works. The protocol provides increased reliability, low delay,and high throughput to the upper layers, while being obliviousto their specific requirements. This seemingly conflicting goalsare achieved by design, using an on–the–fly network codingstrategy. Our protocol also exploits relay nodes to increasethe overall performance of individual links. Since our protocolnaturally masks random p...

  13. 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

  14. 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

  15. The influences of mesh subdivision on nonlinear fracture analysis for surface cracked structures

    International Nuclear Information System (INIS)

    Shimakawa, T.

    1991-01-01

    The leak-before-break (LBB) concept can be expected to be applied not only to safety assessment, but also to the rationalization of nuclear power plants. The development of a method to evaluate fracture characteristics is required to establish this concept. The finite element method (FEM) is one of the most useful tools for this evaluation. However, the influence of various factors on the solution is not well understood and the reliability has not been fully verified. In this study, elastic-plastic 3D analyses are performed for two kinds of surface cracked structure, and the influence of mesh design is discussed. The first problem is surface crack growth in a carbon steel plate subjected to tension loading. A crack extension analysis is performed under a generation phase simulation using the crack release technique. Numerical instability of the J-integral solution is observed when the number of elements in the thickness direction of the ligament is reduced to three. The influence of mesh design in the ligament on the solution is discussed. The second problem is a circumferential part-through crack in a carbon steel pipe subjected to a bending moment. Two kinds of mesh design are employed, and a comparison between two sets of results shows that the number of elements on the crack surface also affects the solution as well as the number of elements in the ligament. (author)

  16. Coupling LaGrit unstructured mesh generation and model setup with TOUGH2 flow and transport: A case study

    Science.gov (United States)

    Sentís, Manuel Lorenzo; Gable, Carl W.

    2017-11-01

    There are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools will provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 (Pruess et al., 1999) to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. In this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.

  17. Comparison of Gafchromic EBT2 and EBT3 for patient-specific quality assurance: Cranial stereotactic radiosurgery using volumetric modulated arc therapy with multiple noncoplanar arcs

    Energy Technology Data Exchange (ETDEWEB)

    Fiandra, Christian; Fusella, Marco; Filippi, Andrea Riccardo; Ricardi, Umberto; Ragona, Riccardo [Department of Oncology, Radiation Oncology Unit, University of Torino, Turin 10126 (Italy); Giglioli, Francesca Romana [Medical Physics Unit, Azienda Ospedaliera Città della Salute e della Scienza, Turin 10126 (Italy); Mantovani, Cristina [Radiation Oncology Department, Azienda Ospedaliera Città della Salute e della Scienza, Turin 10126 (Italy)

    2013-08-15

    Purpose: Patient-specific quality assurance in volumetric modulated arc therapy (VMAT) brain stereotactic radiosurgery raises specific issues on dosimetric procedures, mainly represented by the small radiation fields associated with the lack of lateral electronic equilibrium, the need of small detectors and the high dose delivered (up to 30 Gy). Gafchromic{sup TM} EBT2 and EBT3 films may be considered the dosimeter of choice, and the authors here provide some additional data about uniformity correction for this new generation of radiochromic films.Methods: A new analysis method using blue channel for marker dye correction was proposed for uniformity correction both for EBT2 and EBT3 films. Symmetry, flatness, and field-width of a reference field were analyzed to provide an evaluation in a high-spatial resolution of the film uniformity for EBT3. Absolute doses were compared with thermoluminescent dosimeters (TLD) as baseline. VMAT plans with multiple noncoplanar arcs were generated with a treatment planning system on a selected pool of eleven patients with cranial lesions and then recalculated on a water-equivalent plastic phantom by Monte Carlo algorithm for patient-specific QA. 2D quantitative dose comparison parameters were calculated, for the computed and measured dose distributions, and tested for statistically significant differences.Results: Sensitometric curves showed a different behavior above dose of 5 Gy for EBT2 and EBT3 films; with the use of inhouse marker-dye correction method, the authors obtained values of 2.5% for flatness, 1.5% of symmetry, and a field width of 4.8 cm for a 5 × 5 cm{sup 2} reference field. Compared with TLD and selecting a 5% dose tolerance, the percentage of points with ICRU index below 1 was 100% for EBT2 and 83% for EBT3. Patients analysis revealed statistically significant differences (p < 0.05) between EBT2 and EBT3 in the percentage of points with gamma values <1 (p= 0.009 and p= 0.016); the percent difference as well as

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Discrete Surface Evolution and Mesh Deformation for Aircraft Icing Applications

    Science.gov (United States)

    Thompson, David; Tong, Xiaoling; Arnoldus, Qiuhan; Collins, Eric; McLaurin, David; Luke, Edward; Bidwell, Colin S.

    2013-01-01

    Robust, automated mesh generation for problems with deforming geometries, such as ice accreting on aerodynamic surfaces, remains a challenging problem. Here we describe a technique to deform a discrete surface as it evolves due to the accretion of ice. The surface evolution algorithm is based on a smoothed, face-offsetting approach. We also describe a fast algebraic technique to propagate the computed surface deformations into the surrounding volume mesh while maintaining geometric mesh quality. Preliminary results presented here demonstrate the ecacy of the approach for a sphere with a prescribed accretion rate, a rime ice accretion, and a more complex glaze ice accretion.

  9. Procedure for the automatic mesh generation of innovative gear teeth

    Directory of Open Access Journals (Sweden)

    Radicella Andrea Chiaramonte

    2016-01-01

    Full Text Available After having described gear wheels with teeth having the two sides constituted by different involutes and their importance in engineering applications, we stress the need for an efficient procedure for the automatic mesh generation of innovative gear teeth. First, we describe the procedure for the subdivision of the tooth profile in the various possible cases, then we show the method for creating the subdivision mesh, defined by two series of curves called meridians and parallels. Finally, we describe how the above procedure for automatic mesh generation is able to solve specific cases that may arise when dealing with teeth having the two sides constituted by different involutes.

  10. Watermarking on 3D mesh based on spherical wavelet transform.

    Science.gov (United States)

    Jin, Jian-Qiu; Dai, Min-Ya; Bao, Hu-Jun; Peng, Qun-Sheng

    2004-03-01

    In this paper we propose a robust watermarking algorithm for 3D mesh. The algorithm is based on spherical wavelet transform. Our basic idea is to decompose the original mesh into a series of details at different scales by using spherical wavelet transform; the watermark is then embedded into the different levels of details. The embedding process includes: global sphere parameterization, spherical uniform sampling, spherical wavelet forward transform, embedding watermark, spherical wavelet inverse transform, and at last resampling the mesh watermarked to recover the topological connectivity of the original model. Experiments showed that our algorithm can improve the capacity of the watermark and the robustness of watermarking against attacks.

  11. Vertex Normals and Face Curvatures of Triangle Meshes

    KAUST Repository

    Sun, Xiang

    2016-08-12

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

  12. 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.

  13. Use of mesh in laparoscopic paraesophageal hernia repair

    DEFF Research Database (Denmark)

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

    2015-01-01

    Introduction. Mesh augmentation seems to reduce recurrences following laparoscopic paraesophageal hernia repair (LPHR). However, there is an uncertain risk of mesh-associated complications. Risk-benefit analysis might solve the dilemma. Materials and Methods. A systematic literature search...... potential benefits of LMAH. All data regarding LMAH were used to estimate risk of mesh-associated complications. Risk-benefit analysis was performed using a Markov Monte Carlo decision-analytic model. Results. Meta-analysis of 3 RCTs and 9 OCSs including 915 patients revealed a significantly lower...

  14. Numerical convergence of discrete exterior calculus on arbitrary surface meshes

    KAUST Repository

    Mohamed, Mamdouh S.

    2018-02-13

    Discrete exterior calculus (DEC) is a structure-preserving numerical framework for partial differential equations solution, particularly suitable for simplicial meshes. A longstanding and widespread assumption has been that DEC requires special (Delaunay) triangulations, which complicated the mesh generation process especially for curved surfaces. This paper presents numerical evidence demonstrating that this restriction is unnecessary. Convergence experiments are carried out for various physical problems using both Delaunay and non-Delaunay triangulations. Signed diagonal definition for the key DEC operator (Hodge star) is adopted. The errors converge as expected for all considered meshes and experiments. This relieves the DEC paradigm from unnecessary triangulation limitation.

  15. 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

  16. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2014-02-01

    In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a distributed MAC protocol called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs. TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it receives a sufficient number of grant control messages from these neighbors. A grant message indicates that the associated data packet has the lowest timestamp of all the packets pending transmission at the local transmit queue. We demonstrate that a loose ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily integrated in existing 802.11-based WMNs. Our simulation results show that TMAC achieves excellent resource allocation fairness while maintaining over 90% of maximum link capacity across a large number of topologies.

  17. 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)

  18. Effects of mesh size and escape gaps on discarding in an Australian giant mud crab (Scylla serrata trap fishery.

    Directory of Open Access Journals (Sweden)

    Matt K Broadhurst

    Full Text Available In response to concerns over excessive discarding from Australian recreational round traps (with four funnel entrances used to target giant mud crabs, Scylla serrata, an experiment was done to assess the independent and cumulative utility of paired, bottom-located horizontal escape gaps (46×120 mm and increasing mesh size (from 51 to 101 mm. Compared to conventional traps comprising 51-mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 95% undersize (<85 mm carapace length--CL crabs while maintaining legal catches. Traps made from 101-mm mesh (but with the same funnel entrances as conventional designs and with and without escape gaps similarly retained fewer undersize crabs and also yellowfin bream Acanthopagrus australis (the key bycatch species by up to 94%, but there were concomitant reductions in fishing power for legal sizes of S. serrata. Although there were no immediate mortalities among any discarded crabs, there was a greater bias towards wounding among post molts than late inter-molts and less damage to individuals in the 101-mm conventional than 51-mm conventional traps (without escape gaps. The results support retrospectively fitting escape gaps in conventional S. serrata traps as a means for reducing discarding, but additional work is required to determine appropriate mesh sizes/configurations that maximize species and size selectivity.

  19. Direct metal laser sintering (DMLS) of a customized titanium mesh for prosthetically guided bone regeneration of atrophic maxillary arches.

    Science.gov (United States)

    Ciocca, L; Fantini, M; De Crescenzio, F; Corinaldesi, G; Scotti, R

    2011-11-01

    This study describes a protocol for the direct manufacturing of a customized titanium mesh using CAD-CAM procedures and rapid prototyping to augment maxillary bone and minimize surgery when severe atrophy or post-oncological deformities are present. Titanium mesh and particulate autogenous plus bovine demineralised bone were planned for patient rehabilitation. Bone augmentation planning was performed using the pre-op CT data set in relation to the prosthetic demands, minimizing the bone volume to augment at the minimum necessary for implants. The containment mesh design was used to prototype the 0.6 mm thickness customized titanium mesh, by direct metal laser sintering. The levels of regenerated bone were calculated using the post-op CT data set, through comparison with the pre-op CT data set. The mean vertical height difference of the crestal bone was 2.57 mm, while the mean buccal-palatal dimension of thickness difference was 3.41 mm. All planned implants were positioned after an 8 month healing period using two-step implant surgery, and finally restored with a partial fixed prosthesis. We present a viable and reproducible method to determine the correct bone augmentation prior to implant placement and CAD-CAM to produce a customized direct laser-sintered titanium mesh that can be used for bone regeneration.

  20. Polyhedral meshing as an innovative approach to computational domain discretization of a cyclone in a fluidized bed CLC unit

    Directory of Open Access Journals (Sweden)

    Sosnowski Marcin

    2017-01-01

    Full Text Available Chemical Looping Combustion (CLC is a technology that allows the separation of CO2, which is generated by the combustion of fossil fuels. The majority of process designs currently under investigation are systems of coupled fluidized beds. Advances in the development of power generation system using CLC cannot be introduced without using numerical modelling as a research tool. The primary and critical activity in numerical modelling is the computational domain discretization. It influences the numerical diffusion as well as convergence of the model and therefore the overall accuracy of the obtained results. Hence an innovative approach of computational domain discretization using polyhedral (POLY mesh is proposed in the paper. This method reduces both the numerical diffusion of the mesh as well as the time cost of preparing the model for subsequent calculation. The major advantage of POLY mesh is that each individual cell has many neighbours, so gradients can be much better approximated in comparison to commonly-used tetrahedral (TET mesh. POLYs are also less sensitive to stretching than TETs which results in better numerical stability of the model. Therefore detailed comparison of numerical modelling results concerning subsection of CLC system using tetrahedral and polyhedral mesh is covered in the paper.

  1. Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms.

    Science.gov (United States)

    O'Hara, Ryan P; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N

    2016-02-27

    Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

  2. Repairing a Facial Cleft by Polyether-Ether-Ketone Implant Combined With Titanium Mesh.

    Science.gov (United States)

    Deng, Yuan; Tang, Weiwei; Li, Zhengkang

    2018-05-15

    The Tessier Number 4 cleft is one of the rarest, most complex craniofacial anomalies that presents difficulties in surgical treatment. In this article, we report a case of simultaneous facial depression, eye displacement, and medial canthus deformity. In this case, the maxillary bony defect was reconstructed using computer-assisted design computer-assisted manufacturing (CAD-CAM) polyether-ether-ketone (PEEK) material, and the orbital floor defect was repaired with AO prefabricated titanium mesh. Additionally, the medial canthus was modified with canthopexy and a single Z-plasty flap. Owing to its relative rarity and varied clinical presentations, no definitive operative methods have been accepted for Tessier No. 4 facial cleft. This study presents the combination of CAD-CAM manufactured PEEK material and titanium mesh as an alternative approach for reconstructing the bony defect of Tessier No. 4 facial clefts.

  3. Fluid flow and heat transfer investigation of pebble bed reactors using mesh-adaptive LES

    International Nuclear Information System (INIS)

    Pavlidis, Dimitrios; Lathouwers, Danny

    2013-01-01

    The very high temperature reactor is one of the designs currently being considered for nuclear power generation. One its variants is the pebble bed reactor in which the coolant passes through complex geometries (pores) at high Reynolds numbers. A computational fluid dynamics model with anisotropic mesh adaptivity is used to investigate coolant flow and heat transfer in such reactors. A novel method for implicitly incorporating solid boundaries based on multi-fluid flow modelling is adopted. The resulting model is able to resolve and simulate flow and heat transfer in randomly packed beds, regardless of the actual geometry, starting off with arbitrarily coarse meshes. The model is initially evaluated using an orderly stacked square channel of channel-height-to-particle diameter ratio of unity for a range of Reynolds numbers. The model is then applied to the face-centred cubical geometry. coolant flow and heat transfer patterns are investigated

  4. Kinetic mesh-free method for flutter prediction in turbomachines

    Indian Academy of Sciences (India)

    Mesh-free kinetic upwind scheme; unsteady flows; modified CIR splitting ... scheme for solving the inviscid compressible Euler equations of gas ..... typically carried out for about five cycles in which the periodic behaviour of the flow is captured.

  5. Inductive Cross Shaped Metal Meshes in Silicon Substrate

    National Research Council Canada - National Science Library

    Sternberg, O; Moller, K. D; Grebel, H; Stewart, K. P; Henry, R. M

    2002-01-01

    .... The Micro-Stripes program was used for the calculation of resonance wavelength and width of resonance of cross shaped metal meshes and best- fit formulas were developed for the presentation of the data...

  6. Numerical convergence of discrete exterior calculus on arbitrary surface meshes

    KAUST Repository

    Mohamed, Mamdouh S.; Hirani, Anil N.; Samtaney, Ravi

    2018-01-01

    Discrete exterior calculus (DEC) is a structure-preserving numerical framework for partial differential equations solution, particularly suitable for simplicial meshes. A longstanding and widespread assumption has been that DEC requires special

  7. Dynamic power control for wireless backbone mesh networks: a survey

    CSIR Research Space (South Africa)

    Olwal, TO

    2010-01-01

    Full Text Available points of failures, and robust against RF interference, obstacles or power outage. This is because WMRs forming wireless backbone mesh networks (WBMNs) are built on advanced physical technologies. Such nodes perform both accessing and forwarding...

  8. 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

  9. Metal Mesh Filters for Terahertz Receivers, Phase II

    Data.gov (United States)

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

  10. Comparative Study of Different Gill Net Mesh Sizes in the ...

    African Journals Online (AJOL)

    Bioline

    component weighting) in the catch, which were favoured by the bigger mesh sizes (70mm). ... METHODS ... fishes from each ice chest were identified using the ..... feeding habits), and population (abundance) (RPI ... biomass per unit effort.

  11. Application-specific mesh-based heterogeneous FPGA architectures

    CERN Document Server

    Parvez, Husain

    2011-01-01

    This volume presents a new exploration environment for mesh-based, heterogeneous FPGA architectures. Readers will find a description of state-of-the-art techniques for reducing area requirements, which both increase performance and enable power reduction.

  12. 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.

  13. Constructing C1 Continuous Surface on Irregular Quad Meshes

    Institute of Scientific and Technical Information of China (English)

    HE Jun; GUO Qiang

    2013-01-01

    A new method is proposed for surface construction on irregular quad meshes as extensions to uniform B-spline surfaces. Given a number of control points, which form a regular or irregular quad mesh, a weight function is constructed for each control point. The weight function is defined on a local domain and is C1 continuous. Then the whole surface is constructed by the weighted combination of all the control points. The property of the new method is that the surface is defined by piecewise C1 bi-cubic rational parametric polynomial with each quad face. It is an extension to uniform B-spline surfaces in the sense that its definition is an analogy of the B-spline surface, and it produces a uniform bi-cubic B-spline surface if the control mesh is a regular quad mesh. Examples produced by the new method are also included.

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

    KAUST Repository

    Pellenard, Bertrand; Alliez, Pierre; Morvan, Jean-Marie

    2011-01-01

    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

  15. 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.

  16. 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.)

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

    African Journals Online (AJOL)

    Abstract. This is the 2014 updated guideline and position statement from the South African Urogynaecology Association on the use of transvaginal mesh for the surgical correction of pelvic organ prolapse.

  18. 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

  19. Kinetic mesh-free method for flutter prediction in turbomachines

    Indian Academy of Sciences (India)

    -based mesh-free method for unsteady flows. ... Council for Scientific and Industrial Research, National Aerospace Laboratories, Computational and Theoretical Fluid Dynamics Division, Bangalore 560 017, India; Engineering Mechanics Unit, ...

  20. 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.

  1. 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

  2. Titanium mesh as a low-profile alternative for tension-band augmentation in patella fracture fixation: A biomechanical study.

    Science.gov (United States)

    Dickens, Aaron J; Salas, Christina; Rise, LeRoy; Murray-Krezan, Cristina; Taha, Mahmoud Reda; DeCoster, Thomas A; Gehlert, Rick J

    2015-01-01

    We performed a simple biomechanical study to compare the fixation strength of titanium mesh with traditional tension-band augmentation, which is a standard treatment for transverse patella fractures. We hypothesised that titanium mesh augmentation is not inferior in fixation strength to the standard treatment. Twenty-four synthetic patellae were tested. Twelve were fixed with stainless steel wire and parallel cannulated screws. Twelve were fixed with parallel cannulated screws, augmented with anterior titanium mesh and four screws. A custom test fixture was developed to simulate a knee flexed to 90°. A uniaxial force was applied to the simulated extensor mechanism at this angle. A non-inferiority study design was used to evaluate ultimate force required for failure of each construct as a measure of fixation strength. Stiffness of the bone/implant construct, fracture gap immediately prior to failure, and modes of failure are also reported. The mean difference in force at failure was -23.0 N (95% CI: -123.6 to 77.6N) between mesh and wire constructs, well within the pre-defined non-inferiority margin of -260 N. Mean stiffness of the mesh and wire constructs were 19.42 N/mm (95% CI: 18.57-20.27 N/mm) and 19.49 N/mm (95% CI: 18.64-20.35 N/mm), respectively. Mean gap distance for the mesh constructs immediately prior to failure was 2.11 mm (95% CI: 1.35-2.88 mm) and 3.87 mm (95% CI: 2.60-5.13 mm) for wire constructs. Titanium mesh augmentation is not inferior to tension-band wire augmentation when comparing ultimate force required for failure in this simplified biomechanical model. Results also indicate that stiffness of the two constructs is similar but that the mesh maintains a smaller fracture gap prior to failure. The results of this study indicate that the use of titanium mesh plating augmentation as a low-profile alternative to tension-band wiring for fixation of transverse patella fractures warrants further investigation. Copyright © 2015 Elsevier Ltd. All

  3. 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.

  4. 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 schemeto generate mesh for complex 3-D geometric models is given, which consists of 4 steps: (1) createnodes in 3-D models by ball-packing method, (2) connect nodes to generate mesh by 3-D Delaunaytriangulation, (3) retrieve the boundary of the model after Delaunay triangulation, (4) improve themesh.

  5. Feedforward Control of Gear Mesh Vibration Using Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Gerald T. Montague

    1994-01-01

    Full Text Available This article presents a novel means for suppressing gear mesh related vibrations. The key components in this approach are piezoelectric actuators and a high-frequency, analog feed forward controller. Test results are presented and show up to a 70% reduction in gear mesh acceleration and vibration control up to 4500 Hz. The principle of the approach is explained by an analysis of a harmonically excited, general linear vibratory system.

  6. Mesh Generation via Local Bisection Refinement of Triangulated Grids

    Science.gov (United States)

    2015-06-01

    Science and Technology Organisation DSTO–TR–3095 ABSTRACT This report provides a comprehensive implementation of an unstructured mesh generation method...and Technology Organisation 506 Lorimer St, Fishermans Bend, Victoria 3207, Australia Telephone: 1300 333 362 Facsimile: (03) 9626 7999 c© Commonwealth...their behaviour is critically linked to Maubach’s method and the data structures N and T . The top- level mesh refinement algorithm is also presented

  7. 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...

  8. 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).

  9. A general boundary capability embedded in an orthogonal mesh

    International Nuclear Information System (INIS)

    Hewett, D.W.; Yu-Jiuan Chen

    1995-01-01

    The authors describe how they hold onto orthogonal mesh discretization when dealing with curved boundaries. Special difference operators were constructed to approximate numerical zones split by the domain boundary; the operators are particularly simple for this rectangular mesh. The authors demonstrated that this simple numerical approach, termed Dynamic Alternating Direction Implicit, turned out to be considerably more efficient than more complex grid-adaptive algorithms that were tried previously

  10. Vaginal Approaches Using Synthetic Mesh to Treat Pelvic Organ Prolapse

    OpenAIRE

    Moon, Jei Won; Chae, Hee Dong

    2016-01-01

    Pelvic organ prolapse (POP) is a very common condition in elderly women. In women with POP, a sacrocolpopexy or a vaginal hysterectomy with anterior and posterior colporrhaphy has long been considered as the gold standard of treatment. However, in recent decades, the tendency to use a vaginal approach with mesh for POP surgery has been increasing. A vaginal approach using mesh has many advantages, such as its being less invasive than an abdominal approach and easier to do than a laparoscopic ...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. Hydrodynamics in full general relativity with conservative adaptive mesh refinement

    Science.gov (United States)

    East, William E.; Pretorius, Frans; Stephens, Branson C.

    2012-06-01

    There is great interest in numerical relativity simulations involving matter due to the likelihood that binary compact objects involving neutron stars will be detected by gravitational wave observatories in the coming years, as well as to the possibility that binary compact object mergers could explain short-duration gamma-ray bursts. We present a code designed for simulations of hydrodynamics coupled to the Einstein field equations targeted toward such applications. This code has recently been used to study eccentric mergers of black hole-neutron star binaries. We evolve the fluid conservatively using high-resolution shock-capturing methods, while the field equations are solved in the generalized-harmonic formulation with finite differences. In order to resolve the various scales that may arise, we use adaptive mesh refinement (AMR) with grid hierarchies based on truncation error estimates. A noteworthy feature of this code is the implementation of the flux correction algorithm of Berger and Colella to ensure that the conservative nature of fluid advection is respected across AMR boundaries. We present various tests to compare the performance of different limiters and flux calculation methods, as well as to demonstrate the utility of AMR flux corrections.

  16. How MESSENGER Meshes Simulations and Games with Citizen Science

    Science.gov (United States)

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

    2010-12-01

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

  17. 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.

  18. 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.

  19. 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.

  20. 3D Mesh Compression and Transmission for Mobile Robotic Applications

    Directory of Open Access Journals (Sweden)

    Bailin Yang

    2016-01-01

    Full Text Available Mobile robots are useful for environment exploration and rescue operations. In such applications, it is crucial to accurately analyse and represent an environment, providing appropriate inputs for motion planning in order to support robot navigation and operations. 2D mapping methods are simple but cannot handle multilevel or multistory environments. To address this problem, 3D mapping methods generate structural 3D representations of the robot operating environment and its objects by 3D mesh reconstruction. However, they face the challenge of efficiently transmitting those 3D representations to system modules for 3D mapping, motion planning, and robot operation visualization. This paper proposes a quality-driven mesh compression and transmission method to address this. Our method is efficient, as it compresses a mesh by quantizing its transformed vertices without the need to spend time constructing an a-priori structure over the mesh. A visual distortion function is developed to govern the level of quantization, allowing mesh transmission to be controlled under different network conditions or time constraints. Our experiments demonstrate how the visual quality of a mesh can be manipulated by the visual distortion function.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Biomimetic synthesis of interlaced mesh structures TiO{sub 2} nanofibers with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guanghui [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 China (China); Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin 300072 China (China); Zhang, Tianyong, E-mail: tyzhang@tju.edu.cn [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 China (China); Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin 300072 China (China); Li, Bin, E-mail: libin@tju.edu.cn [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 China (China); Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin 300072 China (China); Zhang, Xia; Chen, Xingwei [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 China (China)

    2016-05-25

    A facile and economical method assisted by PPs (the spongy white peels of pomelo peel) was applied for preparing interlaced mesh structures TiO{sub 2} nanofibers by a liquid impregnation method followed by a calcination process in this study. And the as-prepared materials were comprehensively investigated by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, UV-vis diffuse reflectance spectroscopy, photoluminescence spectra and N{sub 2} adsorption-desorption. The resultant TiO{sub 2} materials exhibit unique morphology, in which the curly nanofibers with the diameter about 90 nm interweave each other for assembling hierarchical mesh structures and there are abundant grooves on the surface of the nanofibers. During the bio-inspired synthetic process, the PPs play important roles as template and induction for forming the hierarchical mesh structures of TiO{sub 2} nanofibers. Furthermore, some of the as-prepared TiO{sub 2} samples exhibit 99% degradation rate for methyl orange in 30 min under UV light irradiation, which can be ascribed to the larger surface area and the unique hierarchical mesh structures. In addition, the stability tests of 5 cycling runs of the photocatalysts indicate that the as-prepared TiO{sub 2} nanofibers can be applied as a practical photocatalyst for degrading organic dyes under UV light irradiation. Therefore, hopefully, the strategy for preparing the TiO{sub 2} nanofibers can be extended to design many more powerful photocatalysts for the environmental remediation in the near future. - Graphical abstract: The TiO{sub 2} nanofibers with interlaced mesh structures were prepared with PPs (the spongy white peels of pomelo peel) as the reactive substrate and directing template, and titanium tetrachloride (TiCl{sub 4}) as titanium resource. And the as-prepared TiO{sub 2} samples exhibit highly photocatalytic activity and good stability for degrading methyl orange under UV light irradiation. - Highlights: • A

  7. 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

  8. 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

  9. Development of a coarse mesh code for the solution of two group static diffusion problems

    International Nuclear Information System (INIS)

    Barros, R.C. de.

    1985-01-01

    This new coarse mesh code designed for the solution of 2 and 3 dimensional static diffusion problems, is based on an alternating direction method which consists in the solution of one dimensional problem along each coordinate direction with leakage terms for the remaining directions estimated from previous interactions. Four versions of this code have been developed: AD21 - 2D - 1/4, AD21 - 2D - 4/4, AD21 - 3D - 1/4 and AD21 - 3D - 4/4; these versions have been designed for 2 and 3 dimensional problems with or without 1/4 symmetry. (Author) [pt

  10. 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.

  11. 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

  12. Performance Evaluation of Various STL File Mesh Refining Algorithms Applied for FDM-RP Process

    Science.gov (United States)

    Ledalla, Siva Rama Krishna; Tirupathi, Balaji; Sriram, Venkatesh

    2018-06-01

    Layered manufacturing machines use the stereolithography (STL) file to build parts. When a curved surface is converted from a computer aided design (CAD) file to STL, it results in a geometrical distortion and chordal error. Parts manufactured with this file, might not satisfy geometric dimensioning and tolerance requirements due to approximated geometry. Current algorithms built in CAD packages have export options to globally reduce this distortion, which leads to an increase in the file size and pre-processing time. In this work, different mesh subdivision algorithms are applied on STL file of a complex geometric features using MeshLab software. The mesh subdivision algorithms considered in this work are modified butterfly subdivision technique, loops sub division technique and general triangular midpoint sub division technique. A comparative study is made with respect to volume and the build time using the above techniques. It is found that triangular midpoint sub division algorithm is more suitable for the geometry under consideration. Only the wheel cap part is then manufactured on Stratasys MOJO FDM machine. The surface roughness of the part is measured on Talysurf surface roughness tester.

  13. A novel finite volume discretization method for advection-diffusion systems on stretched meshes

    Science.gov (United States)

    Merrick, D. G.; Malan, A. G.; van Rooyen, J. A.

    2018-06-01

    This work is concerned with spatial advection and diffusion discretization technology within the field of Computational Fluid Dynamics (CFD). In this context, a novel method is proposed, which is dubbed the Enhanced Taylor Advection-Diffusion (ETAD) scheme. The model equation employed for design of the scheme is the scalar advection-diffusion equation, the industrial application being incompressible laminar and turbulent flow. Developed to be implementable into finite volume codes, ETAD places specific emphasis on improving accuracy on stretched structured and unstructured meshes while considering both advection and diffusion aspects in a holistic manner. A vertex-centered structured and unstructured finite volume scheme is used, and only data available on either side of the volume face is employed. This includes the addition of a so-called mesh stretching metric. Additionally, non-linear blending with the existing NVSF scheme was performed in the interest of robustness and stability, particularly on equispaced meshes. The developed scheme is assessed in terms of accuracy - this is done analytically and numerically, via comparison to upwind methods which include the popular QUICK and CUI techniques. Numerical tests involved the 1D scalar advection-diffusion equation, a 2D lid driven cavity and turbulent flow case. Significant improvements in accuracy were achieved, with L2 error reductions of up to 75%.

  14. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  15. Shear force bond analysis between acrylic resin bases and retention framework (open- and mesh-type)

    Science.gov (United States)

    Royhan, A.; Indrasari, M.; Masulili, C.

    2017-08-01

    Occlusions between teeth and the activity of the muscles around an artificial tooth during mastication create a force on dentures. This force causes friction between acrylic resin bases and retention frameworks that can lead to the complete loss of the acrylic resin base from the framework. The purpose of this study was to analyze the design of retention frameworks and determine which ones have a better resistance to shear forces in order to prevent the loss of heat cured acrylic resin base (HCARB). Six samples each of open-and mesh-type retention frameworks, both types made of Co-Cr material, and HCARB, were shear tested by means of a universal testing machine. The average shear force required to release the HCARB for mesh-type retention frameworks was 28.84 kgf, and the average for the open-type was 26.52 kgf. There was no significant difference between the shear forces required to remove HCARB from open- and mesh-type retention frameworks.

  16. Monte Carlo charged-particle tracking and energy deposition on a Lagrangian mesh.

    Science.gov (United States)

    Yuan, J; Moses, G A; McKenty, P W

    2005-10-01

    A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted mesh cells, particle relocation on the moving mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.

  17. Wire-Mesh Tomography Measurements of Void Fraction in Rectangular Bubble Columns

    International Nuclear Information System (INIS)

    Reddy Vanga, B.N.; Lopez de Bertodano, M.A.; Zaruba, A.; Prasser, H.M.; Krepper, E.

    2004-01-01

    Bubble Columns are widely used in the process industry and their scale-up from laboratory scale units to industrial units have been a subject of extensive study. The void fraction distribution in the bubble column is affected by the column size, superficial velocity of the dispersed phase, height of the liquid column, size of the gas bubbles, flow regime, sparger design and geometry of the bubble column. The void fraction distribution in turn affects the interfacial momentum transfer in the bubble column. The void fraction distribution in a rectangular bubble column 10 cm wide and 2 cm deep has been measured using Wire-Mesh Tomography. Experiments were performed in an air-water system with the column operating in the dispersed bubbly flow regime. The experiments also serve the purpose of studying the performance of wire-mesh sensors in batch flows. A 'wall peak' has been observed in the measured void fraction profiles, for the higher gas flow rates. This 'wall peak' seems to be unique, as this distribution has not been previously reported in bubble column literature. Low gas flow rates yielded the conventional 'center peak' void profile. The effect of column height and superficial gas velocity on the void distribution has been investigated. Wire-mesh Tomography also facilitates the measurement of bubble size distribution in the column. This paper presents the measurement principle and the experimental results for a wide range of superficial gas velocities. (authors)

  18. Selective separation of oil and water with special wettability mesh membranes

    KAUST Repository

    Liu, Defei

    2017-02-24

    Due to the different interfacial effects of oil and water, utilizing the special wettability of solid surfaces to design an oil and water separation process has been demonstrated to be an effective approach for oil/water separation. In this report, a simple process has been developed to fabricate special surface wettability mesh membranes. The carbon nanoparticles with diameters of 10 nm were first coated onto the surface of steel wires based on a candle soot coating process. These templates of carbon nanoparticles were then coated with a more stable layer of silica (SiO2) particles via a facile chemical vapor deposition route. After being modified by two separate methods, a superhydrophobic/superoleophilic membrane was obtained by the use of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) and a oleophobic/superhydrophilic membrane was obtained by using poly(diallyldimethylammonium-perfluorooctanoate) (PDDA–PFO). Separation experiments show that these superhydrophobic/superoleophilic or oleophobic/superhydrophilic mesh membranes can be used to selectively separate oil/water with a high flux of more than 930 L m−2 h−1 and a collecting efficiency of over 97%. Furthermore, the repetitions of the separation experiments demonstrate that these superhydrophobic/superoleophilic or oleophobic/superhydrophilic mesh membranes are durable, stable and reusable, making them encouraging candidates for practical oil-polluted water treatment.

  19. In vitro bioactivity of 3D Ti-mesh with bioceramic coatings in simulated body fluid

    Directory of Open Access Journals (Sweden)

    Wei Yi

    2014-09-01

    Full Text Available 3D Ti-mesh has been coated with bioceramics under different coating conditions, such as material compositions and micro-porosity, using a dip casting method. Hydroxyapatite (HA, micro-HA particles (HAp, a bioglass (BG and their different mixtures together with polymer additives were used to control HA-coating microstructures. Layered composites with the following coating-to-substrate designs, such as BG/Ti, HA + BG/BG/Ti and HAp + BG/BG/Ti, were fabricated. The bioactivity of these coated composites and the uncoated Ti-mesh substrate was then investigated in a simulated body fluid (SBF. The Ti-mesh substrate and BG/Ti composite did not induce biomimetic apatite deposition when they were immersed in SBF for the selected BG, a pressable dental ceramic, used in this study. After seven days in SBF, an apatite layer was formed on both HA + BG/BG/Ti and HAp + BG/BG/Ti composites. The difference is the apatite layer on the HAp + BG/BG/Ti composite was rougher and contained more micro-pores, while the apatite layer on the HA + BG/BG/Ti composite was dense and smooth. The formation of biomimetic apatite, being more bioresorbable, is favored for bone regeneration.

  20. Long-term outcome after transvaginal mesh repair of pelvic organ prolapse.

    Science.gov (United States)

    Heinonen, Pia; Aaltonen, Riikka; Joronen, Kirsi; Ala-Nissilä, Seija

    2016-07-01

    The aim of this study was to report long-term subjective and objective outcomes after the transvaginal mesh (TVM) procedure in long-term. Possible late-onset complications were of particular interest. This was a retrospective analysis of TVM performed using Prolift™ transvaginal mesh measuring subjective outcome using validated questionnaires. Objective outcome was assessed using the Pelvic Organ Prolapse Quantification (POP-Q) system using two definitions: POP-Q stage ≤ 1, and vaginal wall prolapse at or above the hymen or vaginal apex not descending below the upper third of the vagina. Complications were reported with the Prosthesis/Graft Complication Classification Code designed by the International Continence Society/International Urogynecological Association (ICS/IUGA). Of 195 patients, 161 (82.6 %) participated this study after a median of 7 years. The scores in questionnaires evaluating urinary (UI) or anal incontinence and constipation or pelvic floor symptoms were low, indicating favorable surgical outcomes. Altogether, 80.1 % of patients were satisfied with the procedure. Anatomical cure was 56.4 % and 69.3 % depending on the definition used. Reoperation due to POP in any compartment was performed in 16.2 % of patients. Mesh exposure rate was 23 %, most of these being asymptomatic and of late onset. Outcome of the TVM procedure was satisfactory. Anatomical cure was inferior to subjective cure. Mesh exposure rate was high; most exposures observed in the long-term were of late onset and were asymptomatic.