Search results for " Mesh"
showing 10 items of 304 documents
Performance Analysis in Spatially Correlated IEEE 802.11 Networks
2012
Wireless mesh networks are difficult to be characterized, especially under multi-hop traffic streams. The problem is that the local view of the channel and the correlation between the buffers of consecutive nodes in a stream path make complicated the identification of the contention level perceived by each station along the time. Such a figure is used in the models based on the so called decoupling assumption for evaluating the final scheduling of simultaneous channel access grants. In this paper we propose a simplified mesh network model focused on capturing the correlation due to the network topology and traffic routes rather than the access protocol state at each node. To this purpose, w…
Broadband Internet Access via Multi-Hop Wireless Mesh Networks: Design, Protocol and Experiments
2010
Published version of an article from the journal: Wireless Personal Communications. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11277-009-9907-9 While bandwidth for Internet access in urban areas is steadily increasing in recent years, many rural areas are still suffering from the effect of the digital divide. This paper presents a broadband Internet access paradigm developed in the context of the ADHOCSYS project, which was financed by the European Commission under the 6th Framework Program Information and Society Technologies, within the strategic objective of Broadband for All. Aiming at providing reliable Internet access in rural and mountainous regi…
Transsacral rectocele following combined neurinoma resection: A case report
2015
Highlights • Case of a combined (transsacral and laparoscopic) resection of a presacral tumour. • First described case of a transsacral rectocele two years after this procedure. • Possibility of laparoscopic defect repair of transsacral defects.
STUDIO DEI DIFFUSORI DI SCHROEDER E MODELLAZIONE MEDIANTE DWM (DIGITAL WAVEGUIDE MESH)
2012
Sono stati trattati due differenti argomenti: lo studio della diffusione delle onde acustiche per mezzo dei diffusori di Schroeder e la modellazione acustica tramite la Digital Waveguide Mesh (DWM). E’ stato prima affrontato lo studio delle sequenze numeriche a spettro costante e il modo in cui esse vengono generate. La progettazione dei diffusori è stata studiata, partendo da una formulazione semplificata in campo lontano e variando i parametri di progetto sono stati ricavati i diagrammi polari di diffusione. In particolare, mediante i diagrammi polari in campo lontano è stata considerata la variazione della diffusione al variare della classe di sequenza (QRD, PRD, MLS), della lunghezza N …
Energetic criterion of the error evaluation in the analysis via SGBEM
2006
The Symmetric Galerkin Boundary Element Method (sGbem) is assuming more and more an effective role in the solving problems of mechanics in different fields of engineering [1]. The presence of symmetric and defined in sign algebraic operators make such Method more competitive in comparison to the formulation for collocation. The present work has as objective the improvement of the response in the process of analysis of the system where a first discretizazion has been operated, by using a strategy that allows to operate a estimate of the error. On the base of such estimate it is possible to operate a new discretizazion of the boundary through adaptive procedures.
Primitives detection by a discrete and non linear approach : application to the detection and caracterization of interest points for 3D meshes
2010
This manuscript is dedicated to the detection and caracterization of interest points for 3D meshes. First of all, we show the limitations of the curvature measure on sharp edges, the measure usually used for the analysis of meshes. Then, we present a generalization of the SUSAN operator for meshes, named SUSAN-3D. The saliency measure proposed quantify the local variation of the surface and classify directly the analysed vertices in five classes: salient, crest, flat, valley and cavity. The meshes under consideration are manifolds and can be closed or non-closed, regulars or irregulars, dense or not and noised or not. The accuracy of the SUSAN-3D operator is compared to two curvature operat…
Biologic response of inguinal hernia prosthetics: a comparative study of conventional static meshes versus 3D dynamic implants.
2015
Despite improvements in prosthetics and surgical techniques, the rate of complications following inguinal hernia repair remains high. Among these, discomfort and chronic pain have become a source of increasing concern among surgeons. Poor quality of tissue ingrowth, such as thin scar plates or shrinking scars-typical results with conventional static implants and plugs-may contribute to these adverse events. Recently, a new type of 3D dynamically responsive implant was introduced to the market. This device, designed to be placed fixation-free, seems to induce ingrowth of viable and structured tissue instead of regressive fibrotic scarring. To elucidate the differences in biologic response be…
Inguinal Hernia: Defect Obliteration with the 3D Dynamic Regenerative Scaffold Proflor™.
2021
Prosthetic inguinal hernia repair presents significant challenges. Some of these, such as mesh fixation and quality of the biologic response, are still debated among surgeons. For example, there is no strong consensus regarding a specific condition that characterizes the surgical procedure during herniorrhaphy. This issue concerns management of the hernia defect, which in conventional hernia repair with flat meshes remains patent. However, a critical analysis of typical postoperative complications after inguinal hernia repair reveals that some of these adverse events are related to patency of the hernial opening. Postoperative discomfort, pain with specific movements and even hernia recurre…
Registration of arbitrary multi-view 3D acquisitions
2013
International audience; To register 3D meshes representing smooth surfaces we track the 3D digitization system using photogrammetric techniques and calibrations. We present an example by digitizing a 800 mm x 600 mm portion of a car door. To increase the tracking accuracy the 3D scanner is placed in a cubic frame of side 0.5 m covered with 78 targets. The target frame moves in a volume that is approximately 1100 mm x 850 mm x 900 mm, to digitize the area of interest. Using four cameras this target frame is tracked with of an accuracy of 0.03 mm spatially and 0.180 mrad angularly. A registration accuracy between 0.1 mm and 2 mm is reached. This method can be used for the registration of mesh…
Highly Accurate Conservative Finite Difference Schemes and Adaptive Mesh Refinement Techniques for Hyperbolic Systems of Conservation Laws
2007
We review a conservative finite difference shock capturing scheme that has been used by our research team over the last years for the numerical simulations of complex flows [3, 6]. This scheme is based on Shu and Osher’s technique [9] for the design of highly accurate finite difference schemes obtained by flux reconstruction procedures (ENO, WENO) on Cartesian meshes and Donat-Marquina’s flux splitting [4]. We then motivate the need for mesh adaptivity to tackle realistic hydrodynamic simulations on two and three dimensions and describe some details of our Adaptive Mesh Refinement (AMR) ([2, 7]) implementation of the former finite difference scheme [1]. We finish the work with some numerica…