ABSTRACT
As a new energy source for atrial fibrillation ablation, electric pulse ablation has higher tissue selectivity and biosafety, so it has a great application prospect. At present, there is very limited research on multi-electrode simulated ablation of histological electrical pulse. In this study, a circular multi-electrode ablation model of pulmonary vein will be built on COMSOL5.5 platform for simulation research. The results show that when the voltage amplitude reaches about 900 V, it can make some positions achieve transmural ablation, and the depth of continuous ablation area formed can reach 3 mm when the voltage amplitude reaches 1 200 V. When the distance between catheter electrode and myocardial tissue is increased to 2 mm, a voltage of at least 2 000 V is required to make the depth of continuous ablation area reach 3 mm. Through the simulation of electric pulse ablation with ring electrode, the research results of this project can provide reference for the voltage selection in the clinical application of electric pulse ablation.
Subject(s)
Humans , Heart Rate , Atrial Fibrillation/surgery , Electrodes , Catheter Ablation , ElectricityABSTRACT
Objective: To explore the law of temperature change in hot air drying process, and provide a theoretical basis for improving the drying efficiency and uniformity of Erzhi Pills (EP). Methods: Heat and mass transfer models were established to simulate the temperature distribution of the drying process of EP with no hole bottom and screen hole bottom based on COMSOL Multiphysics. The drying process of EP layer at 60, 80 and 100 ℃ was studied. The effective water diffusion coefficient (Deff) of EP layer was calculated by Fick’s second law plate model. A probe temperature sensor was used to monitor the temperature changes of the intermediate surface and interior of EP layer during the drying process to verify the drying model. Results: The surface and internal temperature of EP layer showed a trend of first sharp rise and then slow rise in the drying process of different hot air temperature. The inner temperature range of the drying model with no hole bottom and screen hole bottom was 55.3-56.0 ℃ and 57.5-57.7 ℃ respectively. The uniformity of drying temperature of EP can be improved by using drying plate with screen hole. The Deff range of the two model experiments were 0.76 × 10-7-2.82 × 10-7 m2/s and 1.15 × 10-7-3.94 × 10-7 m2/s, respectively. The experimental results showed that the model could well reflect the temperature variation of EP layer drying process within a certain drying temperature range. Conclusion: The change of drying temperature was directly reflected through the reliable hot air drying model of EP layer. The study provides reference for the optimization of EP drying process.
ABSTRACT
Objective To put forward a method for 3D electrical impedance finite element joint modeling and simulation using COMSOL for visual modeling and Visual C++ for programming.Methods A model was established with COMSOL,and then transformed into a.stl file and introduced into Visual C++ simulation platform.Delaunay tetrahedral mesh generation algorithm was used for finite element meshing,calculation and simulation,and joint modeling and simulation were realized finally.Results Simulation result showed that the method could be used to introduce COMSOL model and complete 3D finite element simulation.Conclusion The method proves its compatibility with the models generated by multi software and practicability for joint modeling and simulation.
ABSTRACT
Objective To put forward a method for 3D electrical impedance finite element joint modeling and simulation using COMSOL for visual modeling and Visual C++ for programming.Methods A model was established with COMSOL,and then transformed into a.stl file and introduced into Visual C++ simulation platform.Delaunay tetrahedral mesh generation algorithm was used for finite element meshing,calculation and simulation,and joint modeling and simulation were realized finally.Results Simulation result showed that the method could be used to introduce COMSOL model and complete 3D finite element simulation.Conclusion The method proves its compatibility with the models generated by multi software and practicability for joint modeling and simulation.
ABSTRACT
La queratotomía radial es uno de los métodos quirúrgicos empleados para corregir los defectos ópticos de las personas; ésta ha sido ampliamente estudiada, e incluso se han propuesto nomogramas que permiten predecir los resultados de algunas geometrías; a pesar de esto, las experiencias postoperatorias han demostrado que la tasa de éxito de las cirugías es baja, ya que se presenta hipocorrección o hipercorrección de los pacientes, obligándolos a usar ayudas externas o llevándolos a someterse nuevamente a una cirugía. Teniendo en cuenta esto, se desarrolló una plataforma para simular estas cirugías por medio del método de elementos finitos, empleando los programas Matlab y COMSOL Multiphysics. Por medio de la rutina creada es posible obtener un modelo de la córnea preoperatoria que se asemeje tanto en geometría, como en condiciones de esfuerzo, a la córnea real; adicionalmente, es posible adaptar la geometría de la queratotomía radial que desee simularse. Se realizaron simulaciones para una cirugía compuesta de dos arcos y otra de tres arcos; los resultados obtenidos demuestran la capacidad de la simulación numérica para avanzar en el desarrollo de la cirugía refractiva, al ser posible estudiar parámetros, que de forma experimental, son difíciles de tener en cuenta, como la geometría inicial de la córnea y la edad del paciente, lo cual influye en el módulo de elasticidad del material; por otra parte, se encontró que esta aplicación es una potencial herramienta para los oftalmólogos, pues tiene la capacidad de predecir los resultados postoperatorios.
Radial keratotomy is used as a methodology to correct refractive errors. This surgery has been widely studied and also nomograms have been proposed in order to predict postoperative results of some types of keratotomies. Despite these eff orts, surgical evidence has shown a low success rate because of undercorrection or overcorrection, forcing patients to use spectacles or contact lenses, after surgery, or even leads them to a new procedure. A simulation platform was developed in an attempt to study these surgeries, employing the finite element method, using Matlab and COMSOL Multiphysics simultaneously. The routine is capable of simulate the preoperative cornea in terms of geometry and stress configuration. Also, it could be adapted to simulate any kind of radial keratotomy LASIK and PRK surgeries. Simulations for a double arc keratotomy and a triple arc keratotomy were developed. Results provide evidence of the capability of the platform to improve knowledge of refractive surgery taking into account the possibility to analyze the effect produced by corneal geometry and patient age, which aff ects the elastic modulus of the material, parameters difficult to analyze in an in-vivo experiment. Besides, it demonstrates the potential of the program as a tool for the surgeon to plan refractive surgery.
Subject(s)
Keratotomy, Radial/statistics & numerical data , Corneal Surgery, Laser/trends , Cornea/surgery , Ophthalmologic Surgical Procedures/methodsABSTRACT
Objective: In order to understand temporal and spatial distributions of alternating electromagnetic field (AEMF) of a coil thoroughly, the 3-D finite-element models of this kind of Biomagnetic Fields are established and analyzed for the research on bioeffect of magnetic field on microcirculation. Methods: Designing CAD models, setting boundary conditions, meshing models and obtaining numerical solutions were completed all within Comsol Multiphysics in terms of the theory of electromagnetic field. Results: Axial and radial plot of spatial attenuation rate of the AEMF, which were accordance with measured data, were simulated while the temporal and spatial distributions of AEMF were acquired. Conclusion: Models of 3-D finite-element of this kind of biomagnetic fields which appeared to exactly simulate the real magnetic field were first established systematically, and solved the placing problem of magnetic fields for the research on bioeffect of magnetic field on microcirculation and provided platforms for the simulation of hemodynamic of blood flow in the magnetic field.