Search
Filters
total: 321
filtered: 247
Search results for: MESH-FASCIA JUNCTION
-
Modeling of the fascia-mesh system and sensitivity analysis of a junction force after a laparoscopic ventral hernia repair
PublicationW pracy rozpatrywano prosty model cięgnowy układu powięż-siatka do oszacowania siły połączenia siatki z powięzią po operacji laparoskopowej przepukliny brzusznej. Cięgno obciążone jest ciśnieniem wewnątrz brzusznym, symulującym kaszel, oraz przemieszczeniami jego końców wywołanymi skłonami pacjenta. Wpływ poszczególnych parametrów cięgna na siłę połączenia określono za pomocą analizy wrażliwości. Sformułowano pewne wnioski ważne...
-
Cough influence on fascia-mesh system built for a hernia repair - an experimental research
PublicationAn experimental approach to identify stronger and weaker fixation schemes in laparoscopic ventral hernia repair is presented in the paper. Two types of implants, whose mechanical properties are significantly different and five kinds of connectors are considered. Physical models of operated hernia have been built using those materials and porcine abdominal tissue. The models have been subjected to dynamic impulse load, similar to...
-
Physical and mathematical modelling of implant-fascia system in order to improve laparoscopic repair of ventral hernia
PublicationThis paper describes an investigation of biomechanical behaviour of hernia repair, which is focused on the selection of safe linking of certain type of implant with fascia in laparoscopic operation. The strength of various fixations of the implant to the fascia is analysed. Methods: The research is based on experimental observations of operated hernia model behaviour during a dynamic impulse load corresponding to post-operative...
-
EXPERIMENTS AND SIMULATIONS FOR LAPAROSCOPICVENTRAL HERNIA REPAIR IMPROVEMENT
PublicationThe authors conducted a wide experimental and numerical study in order to determine effective approaches in the laparoscopic VH repair. At first the study covered identification of mechanical properties of the abdominal fascia, implants, tacks and transabdominalsutures. Basis on these data, the one and two-dimensional mathematical models were formulated and a number of numerical static and dynamic analyses were carried out. Then...
-
Biomechanics of the front abdominal wall as a potential factorleading to recurrence with laparoscopic ventral hernia repair
PublicationThis study investigated the front abdominal wallto describe its elasticity in vivo and searched for elongationsthat possibly stretched an implanted mesh, therebycausing fixation failure and subsequent recurrence.To measure front abdominal wall elongations, amodel of fascia movements was created. Eight healthyvolunteers were measured during exercise to determine theextent of elongations in their front abdominal wall. Videoswere...
-
Behaviour of orthotropic surgical implant in hernia repair due to the material orientation and abdomen surface deformation
Publicationrelation to the different range of typical deformations observed in different directions and zones of abdomen surface due to the patients’ life activities, has a significant influence on the extreme junction forces in the mesh–tissue connections and hence the repair persistence. The finite element model of the orthotropic implant was developed, and the junction forces in the connections of tissue and mesh were studied. The kinematical...
-
Mechanical behaviour of the implant used in human hernia repair under physiological loads
PublicationIn laparoscopic operations of abdominal hernias some recurrences still take place, even when applying a surgical mesh. This is usually caused by a failure of the connection between the tissue and the implant. The study deals with the influence of an implant’s orientation on forces in joints, which connect the mesh to human tissues. In the paper, the implant is modelled as a membrane structure within framework of the Finite Element...
-
Biomechanical causes for failure of the Physiomesh/Securestrap system
PublicationThis study investigates the mechanical behavior of the Physiomesh/Securestrap system, a hernia repair system used for IPOM procedures associated with high failure rates. The study involved conducting mechanical experiments and numerical simulations to investigate the mechanical behavior of the Physiomesh/Securestrap system under pressure load. Uniaxial tension tests were conducted to determine the elasticity modulus of the Physiomesh...
-
Combined numerical and experimental approach to determine numerical model of abdominal scaffold
PublicationA proper junction of the prosthesis and the abdominal wall is important in successful hernia repair. The number of tacks should be balanced to assure appropriate mesh fixation and not to induce post-operative pain. Numerical simulations help to find this balance. The study is aimed at creating a proper numerical model of a knitted surgical mesh subjected to boundary conditions and load occurring in the abdominal cavity. Continuous,...
-
Orthotropic membrane as a mechanical model of surgical implant in abdominal hernia repair
PublicationEven though the incisional hernia repair surgery is a well known procedure, mechanical properties of the tissue-implant system are unknown so the implantation of the repairing mesh is quite intuitive and, recurrences of the illness still take place. The main objective of the study is to define an operated hernia model that can be used for surgery planning and the assessment of the repair persistence. The load applied to the structure...
-
Accurate Computation of IGBT Junction Temperature in PLECS
PublicationIn the article, a new method to improve the accuracy of the insulated-gate bipolar transistor (IGBT) junction temperature computations in the piecewise linear electrical circuit simulation (PLECS) software is proposed and described in detail. This method allows computing the IGBT junction temperature using a nonlinear compact thermal model of this device in PLECS. In the method, a nonlinear compact thermal model of the IGBT is...
-
Nonreciprocal properties of elliptical ferrite coupled line junction
PublicationIn this paper the nonreciprocal properties of el-liptical ferrite coupled line (EFCL) junction are examined. In the analysis the technique combining spectral-domain approach (SDA) with coupled-mode method (CMM) is applied. The nu-merical results concerning gyromagnetic coupling coefficient of ferrite coupled lines and scattering matrix of EFCL junction are presented. The obtained results are validated with the use of commercial...
-
Effect of mesh deformation on the accuracy of 3D FEM electromagnetic analysis
PublicationIn this paper, the accuracy of 3D FEM electromagnetic simulations in parametric analysis using mesh deformation techniques is discussed. Mesh deformation techniques allow one to preserve the mesh topology while the geometry is changed. It is shown that the application of mesh deformation can provide accurate simulation results even for very large deformations. On the other hand, it is also shown that the technique has to be used...
-
Numerical analysis of CO2-water separation in a horizontal double T-junction
PublicationCarbon dioxide is considered one of the main factors leading to global warming. Considering the significant impacts of CO2 on climate change, various technologies have been developed in recent decades to control carbon emission, such as for example CO2 capture and storage. The developed cycle of a negative CO2 emission power plant includes some devices, out of which, separator plays an indispensable role. To this end, T-junction...
-
Longitudinally magnetized left-handed cylindrical ferrite coupled line junction for nonreciprocal devices
PublicationThis paper presents investigations of longitudinally magnetized left-handed cylindrical ferrite coupled line junction for nonreciprocal devices. The proposed junction is formed as a quasi periodic arrangement of N unit cells. Each unit cell is realized as a cascade of short cylindrical ferrite coupled lines with reactance circuit composed of series capacitors and parallel inductors. The left-handed cylindrical junction with π/4...
-
Measures of region failure survivability for wireless mesh networks
PublicationWireless mesh networks (WMNs) are considered as a promising alternative to wired local, or metropolitan area networks. However, owing to their exposure to various disruptive events, including natural disasters, or human threats, many WMN network elements located close to the failure epicentre are frequently in danger of a simultaneous failure, referred to as a region failure. Therefore, network survivability, being the ability...
-
Objective selection of minimum acceptable mesh refinement for EMC simulations
PublicationOptimization of computational electromagnetics (CEM) simulation models can be costly in both time and computing resources. Mesh refinement is a key parameter in determining the number of unknowns to be processed. In turn, this controls the time and memory required for a simulation. Hence, it is important to use only a mesh that is good enough for the objectives of the simulation, whether for direct handling of high-fidelity EM...
-
Experimental Research of Implant-Fascia Connections
PublicationW pracy przedstawiono wyniki identyfikacji siły zrywającej połączenie implantu z powięzią wykonane z użyciem różnych typów łączników: zszywek lub szwów chirurgicznych. Rozważono pięć typów łączników i pięć typów implantów.
-
Mechanical Properties of Human Abdominal Fascia
PublicationW pracy przedstawiono wyniki identyfikacji modułu sprężystosci i współczynnika Poissona próbek powięzi ściany brzucha człowieka, którą przeprowadzono na podstawie testów jednoosiowego rozciągania.
-
Four-Port Circulator Using Reduced Ground Plane Ferrite Coupled Line Junction
PublicationIn this paper the investigations of four-port circula-tor using longitudinally magnetized ferrite coupled line section are presented. The device is designed by cascading ferrite section with magic-T junction ensuring its even and odd mode excitation. The scattering parameters of ferrite coupled line junction are calculated using own software and verified with the use of commercial software. The even and odd excitation of ferrite...
-
In vivo performance of intraperitoneal onlay mesh after ventral hernia repair
PublicationBackground: Ventral hernia repair needs to be improved since recurrence, postoperative pain and other complications are still reported in many patients. The behavior of implants in vivo is not sufficiently understood to design a surgical mesh mechanically compatible with the human abdominal wall. Methods: This analysis was based on radiological pictures of patients who underwent laparoscopic ventral hernia repair. The pictures...
-
Application of mesh deformation for modeling of conformal RF components with 3D FEM
PublicationIn this paper, a method of analysis of conformal RF components has been proposed. In this approach, modeling of a curved structure is based on mesh deformation of planar objects rather than the construction of conformal geometry at CSG level. Since the model is represented as a 3D mesh, the deformation only requires the calculation of nodes position in the bent structure. The results of the proposed algorithm have been validated...
-
Mechanical behaviour of knit synthetic mesh used in hernia surgery
PublicationPurpose: There is a discussion in literature concerning mechanical properties and modelling of surgical meshes. An important feature of elastic modulus dependency on load history is taken into account in this paper, as implants are subjected to variable loading during human activity. The example of DynaMesh®-IPOM surgical implant is studied. Methods: The analysis is based on failure tension tests and cyclic loading and unloading...
-
Local Mesh Deformation for accelerated parametric studies based on the Finite Element Method
PublicationThis paper presents an approach for enhancing the efficiency of two-dimensional Finite Element Method analysis in parametric studies or optimisation process of microwave components. The new approach involves local mesh deformation applied near the elements that are modified during computations. Since in the proposed approach the topology of the mesh remains unchanged, a new mesh does not have to be generated from scratch when the...
-
Mesh dependence study for numerical assessment of hydrodynamic characteristics of windsurfing fin
PublicationThe presented research aims to assess the drag coefficient and lift coefficient versus angle of attack curves for windsurfing fin. Special attention in the research was being paid to the evaluation of the stall angle value. The angle of incidence for which the stall occurs was searched, and the sensitivity of the solution for the mesh resolution was studied. The mesh resolution sensitivity analysis was done by systematically decreasing...
-
Influence of mesh density on 2D viscous flutter in a turbomachinery cascade
PublicationIn this study numerical simulations of 2D viscous flutter were performed and compared with available experimental results for various mesh densities and flow parameters. Calculations were carried out for the bending oscillations of an Eleventh Standard Configuration cascade. ANSYS CFX code was used for the SST, SA and k-ω turbulence model calculations.
-
A hybrid-mesh solution for coverage issues in WiMAX metropolitan area networks.
PublicationThe new WiMAX technology offers several advantages over the currently available (GSM or UMTS-based) solutions. It is a cost effective, evolving, and robust technology providing quality of service guarantees, high reliability, wide coverage and non-line-of-sight (NLOS) transmission capabilities. All these features make it particularly suitable for densely populated urban environments. In this paper we discuss the design and implementation...
-
Is mesh fixation necessary in laparoendoscopic techniques for M3 inguinal defects? An experimental study.
Publicationrepairs, in case of large direct hernias (M3) mesh fixation is recommended to reduce recurrence risk. Despite lack of highquality evidence, the recommendation was upgraded to strong by expert panel. The authors conducted a research experiment to verify the hypothesis that it is possible to preserve the mesh in the operating field in large direct hernias (M3) without the need to use fixing materials. Method The authors conducted...
-
Cross-layer mDNS/ARP integration for IEEE 802.11s Wireless mesh Network
PublicationPopularization of mobile computing devices created a need for robust, efficient and ubiquitous methods of communication and network access. At the same time, evolution and standardization of Wireless Local Area Network (WLAN) technologies made them an attractive solution for building of complex network systems. Moreover, growing maturity of WLAN standards such as IEEE 802.11 allows for introduction of WLAN architectures other than...
-
Local mesh morphing technique for parametrized macromodels in the finite element method
PublicationThis paper presents a novel approach for enhancing the efficiency of the design process of microwave devices by means of the finite element method. It combines mesh morphing with local model order reduction (MOR) and yields parametrized macromodels that can be used to significantly reduce the number of variables in the FEM system of equations and acceleration of computer simulation. A projection basis for local reduction is generated...
-
Self-Adaptive Mesh Generator for Global Complex Roots and Poles Finding Algorithm
PublicationIn any global method of searching for roots and poles, increasing the number of samples increases the chances of finding them precisely in a given area. However, the global complex roots and poles finding algorithm (GRPF) (as one of the few) has direct control over the accuracy of the results. In addition, this algorithm has a simple condition for finding all roots and poles in a given area: it only requires a sufficiently dense...
-
Mechanics of mesh implanted into abdominal wall under repetitive load. Experimental and numerical study
PublicationThere are a number of papers discussing medical and mechanical aspects of ventral hernia management. Despite intensive work on the problem understanding, recurrences of the sickness still happen too often. For that reason new aspects of the problem must be considered. In this paper, a change in the abdominal implant’s stiffness is discussed, which is caused by cyclic loading. Such loading influence abdominal implant e.g. while...
-
Router Selfishness in Community Wireless Mesh Networks: Cross-Layer Benefits and Harms
PublicationWęzły sieci mesh nie są poddane administracyjnej kontroli, zarazem nie odczuwają ograniczeń energetycznych. Są przez to skłonne do zachowań egoistycznych w warstwach 2 i 3 OSI, w szczególności w odniesieniu do protokołów MAC i routingowych. W pracy przebadano symulacyjnie wybrane aspekty środowiska mesh uzasadniające podjęcie ataków egoistycznych i zidentyfikowano trzy: gęstość rozmieszczenia i położenie routerów oraz warstwa OSI...
-
Interworking and Cross-layer Service Discovery Extensions for IEEEE802.11s Wireless Mesh Standard
PublicationWith the rapid popularization of mobile end-user electronic devices wireless network technologies begin to play a crucial role as networks access technologies. While classic point-to-multipoint wireless access systems, based on fixed infrastructure of base stations providing access to clients, remain the main most popular solution, an increasing attention is devoted to wireless mesh systems, where each connecting client can extend...
-
Behaviour of Fascia-Implant Structure under the Impulse Pressure
PublicationW pracy przedstawiono badania eksperymentalne wykonane dla modeli zaoperowanych przepuklin brzusznych poddanych impulsowemu działaniu ciśnienia, analogicznego do kaszlu pooperacyjnego. Zbudowano 57 modeli zgodnie ze sztuką oparacji laparoskopowej, z użyciem powiezi świńskiej, pięciu typów implantów i pięciu rodzajów łączników. Opisano otrzymane wyniki wskazując na mocniejsze i słabsze rozwiązania operacyjne.
-
GPU-Accelerated 3D Mesh Deformation for Optimization Based on the Finite Element Method
PublicationThis paper discusses a strategy for speeding up the mesh deformation process in the design-byoptimization of high-frequency components involving electromagnetic field simulations using the 3D finite element method (FEM). The mesh deformation is assumed to be described by a linear elasticity model of a rigid body; therefore, each time the shape of the device is changed, an auxiliary elasticity finite-element problem must be solved....
-
A 3D-FEM mesh technique for fast analysis of waveguide problems containing rotatable tuning elements
PublicationIn this paper a meshing technique for 3D Finite Element Method is presented. It allows for fast analysis and optimization of the waveguide structures, which contain rotatable tuning elements. In the proposed procedure a thin layer of varying cylindrical mesh buffer is introduced in order to reuse unchanged mesh and FEM matrices in the rest of the domain.
-
A new approach to design of weather disruption-tolerant wireless mesh networks
PublicationWireless Mesh Networks, offering transmission rates of 1–10 Gb/s per a millimeter-wave link (utilizing the 71–86 GHz band) seem to be a promising alternative to fiber optic backbone metropolitan area networks because of significantly lower costs of deployment and maintenance. However, despite providing high transmission rates in good weather conditions, high-frequency wireless links are very susceptible to weather disruptions....
-
CO2 capture through direct-contact condensation in a spray ejector condenser and T- junction separator
PublicationThe design principle underlying the steam condensation and CO2 purification in a gas power plant with a focus on reducing CO2 emissions encompasses the deployment of a spray ejector condenser (SEC) and separator. This innovative system facilitates direct-contact condensation of steam with non-condensable gas (CO2) by inter acting with a spray of subcooled water, seamlessly integrated with a T-junction separator mechanism aimed...
-
Service and Path Discovery Extensions for Self-forming IEEE 802.11s Wireless Mesh Systems
PublicationWith the rapid growth of the quantity and capabilities of end-user electronic devices, both stationary and mobile, they are employed in increasing number of applications. In this situation, wireless network technologies begin to play a crucial role as networks access technologies, as cable-based solutions tend to be of limited utility in case of easily portable or mobile devices. Resulting development of wireless technologies reached...
-
Photovoltaic effect in the single-junction DBP/PTCBI organic system under low intensity of monochromatic light
PublicationPhotoelectric properties of the planar ITO/MoO3/DBP/PTCBI/BCP/Ag system were characterized on the basis of short-circuit current, open-circuit voltage and absorption spectra, and current-voltage measurements in the dark and under monochromatic illumination of low intensity. Photovoltaic performance of the system was compared with the performance of ideal semiconductor and excitonic cells of chosen bandgaps. Such analysis shows,...
-
Mechanical Modelling of Human Fascia in the Problem of Ventral Hernia Repair
PublicationPraca dotyczy badań doświadczalnych tkanki ludzkiej oraz symulacji numerycznej zachowania tej tkanki. Na podstawie eksperymentu dokonuje się identyfikacji modelu materiałowego tkanki a następnie w celu wweryfikacji przeprowadza się symulacje numeryczną zachowania modelowanej struktury. Celem badań jest uzyskanie informacji przydatnych podczas leczenia przepuklin brzusznych u ludzi.
-
Mechanical model of fascia-implant structure. Finite element simulation.
PublicationPraca dotyczy modelowania i symulacji syntetycznych implantów chirurgicznych stosowanych w leczeniu przepulin brzusznych metodą laparoskowpową. Prponowane są modele matematyczne a ich prawidłowość weryfikowana jest na podstawie badań doświadczalnych zachowania się modeli fizycznych wszczepionych implantów pod wpływem obciążeń wynikających z fizjologii człowieka. Nakreślona jest metodologia oceny trwałości połączenia siatki chirurgicznej...
-
A Mesh Deformation Technique Based on Solid Mechanics for Parametric Analysis of High-Frequency Devices With 3-D FEM
PublicationIn this paper, a versatile technique for mesh defor- mation is discussed, targeted at the electromagnetic (EM) field simulation of high-frequency devices using the 3-D finite element method (FEM). The approach proposed applies a linear elasticity model to compute the displacements of the internal mesh nodes in 3-D when the structure geometry is changed. The technique is compared with an alternative approach...
-
A Nonlinear Model of a Mesh Shell
PublicationFor a certain class of elastic lattice shells experiencing finite deformations, a continual model using the equations of the so-called six-parameter shell theory has been proposed. Within this model, the kinematics of the shell is described using six kinematically independent scalar degrees of freedom — the field of displacements and turns, as in the case of the Cosserat continuum, which gives reason to call the model under consideration...
-
Impact of the Finite Element Mesh Structure on the Solution Accuracy of a Two-Dimensional Kinematic Wave Equation
PublicationThe paper presents the influence of the finite element mesh structure on the accuracy of the numerical solution of a two-dimensional linear kinematic wave equation. This equation was solved using a two-level scheme for time integration and a modified finite element method with triangular elements for space discretization. The accuracy analysis of the applied scheme was performed using a modified equation method for three different...
-
SIMULATION OF PROCEED® SURGICAL MESH APPLIED TO VENTRAL HERNIA REPAIR
PublicationIn the present research, Proceed® implant is considered. The system is subjected to short-time dynamic pressure load, similar to post-operative cough naturally occurring in human abdomen. The model refers to a clinical case of 5cm of hernia operated by Proceed implant fixed by 15 joints every 3cm around the orifice. The simulations of the implanted mesh are performed by means of the Finite Element Method. The implant is modelled...
-
Global sensitivity analysis of membrane model of abdominal wall with surgical mesh
PublicationThe paper addresses the issue of ventral hernia repair. Finite Element simulations can be helpful in the optimization of hernia parameters. A membrane abdominal wall model is proposed in two variants: a healthy one and including hernia defect repaired by implant. The models include many uncertainties, e.g. due to variability of abdominal wall, intraabdominal pressure value etc. Measuring mechanical properties with high accuracy...
-
BJS-03 DO WE NEED FIXATION OF THE MESH IN LAPAROENDOSCOPIC TECHNIQUES FOR M3 INGUINAL DEFECTS? AN EXPERIMENTAL STUDY
PublicationThe authors conducted a research experiment to verify the hypothesis that it is possible to preserve the mesh in the operating field in large direct hernias (M3) without the need to use fixing materials. The results showed that mesh fixation is not the only alternative to preventing recurrence in complex defects and that the type of implant seems to be a key factor from the point of view of mechanics and biophysics.
-
Residue-Pole Methods for Variability Analysis of S-parameters of Microwave Devices with 3D FEM and Mesh Deformation
PublicationThis paper presents a new approach for variability analysis of microwave devices with a high dimension of uncertain parameters. The proposed technique is based on modeling an approximation of system by its poles and residues using several modeling methods, including ordinary kriging, Adaptive Polynomial Chaos (APCE), and Support Vector Machine Regression (SVM). The computational cost is compared with the traditional Monte-Carlo...