Search

Background and objective: In magnetic fluid hyperthermia therapy, controlling temperature elevation and optimizing heat generation is an immense challenge in practice. The resultant heating configuration by magnetic fluid in the tumor is closely related to the dispersion of particles, frequency and intensity of magnetic field, and biological tissue properties. Methods: In this study, to solve heat transfer equation, we used COMSOL Multiphysics and to verify the model, an experimental setup has been used. To show the accuracy of the model, simulations have been compared with experimental results. In the second part, by using experimental results of nanoparticles distribution inside Agarose gel according to various gel concentration, 0.5%, 1%, 2%, and 4%, as well as the injection velocity, 4 µL/min, 10 µL/min, 20 µL/min, and 40 µL/min, for 0.3 cc magnetite fluid, power dissipation inside gel has been calculated and used for temperature prediction inside of the gel. Results: The Outcomes demonstrated that by increasing the flow rate injection at determined concentrations, mean temperature drops. In addition, 2% concentration has a higher mean temperature than semi spherical nanoparticles distribution. Conclusion: The results may have implications for treatment of the tumor and any kind of cancer diseases.

The neck fractures and the femurs intertrochanteric are common complications that are recovered by a multicomponent implant called dynamic hip screw (DHS). In the present study, a standard four-hole DHS with Ti6Al4V (Ti6) and SS316l (SS) alloys for static mode (slow walking) and fatigue mode like normal walking (NW), descending stairs (DS), and falling (FA) by finite elements analysis (FEA) have been evaluated (ANSYS software). The results have been confirmed by similar studies in static mode and maximum Von Mises stress and strain are obtained for Ti6 about 145 MPa and 0.191%, and SS about 196 MPa and 0.121%. Most critical stress points occur in cortical screws, plate holes, compression screws, and lag screws, respectively. DHS components with Ti6 alloy have infinite life in NW and DS, also in FA, they have a finite life (107-108 cycle) with alternating Von Mises stress (amax σ) ~ 425 MPa, while for SS they have finite life in all activities, which NW ~107 cycle, DS~106 cycle, and even in FA cortical screw life of failure reaches to 98 cycles and max 486 a σ ? Mpa. The critical regions are the same as the failure regions common in biomechanical and clinical studies. These regions are mainly concentration stress points that lead to DHS failure as the crack grows. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the effect of a number of loading cycles on fabrics bagging behavior, and then investigated the influence of factors such as sample weight, test speed, and sphere diameter on the worsted fabrics bagging behavior using response surface method (RSM). Six worsted fabric types with different weights were prepared and then the bagging properties of these fabrics were measured using a newly developed test method. Bagging parameters including bagging force, work, fatigue, resistance, hysteresis, and residual height are calculated. Then, a statistical model (RSM) was used for the experimental plan (with these factors) to determine the runs of an experiment (or selected points). The experimental results showed that sample weight and sphere diameter have a significant effect while test speed has no significant effect on the bagging parameters. Also, the fitted models of bagging parameters are obtained and coefficient effects are estimated. [ABSTRACT FROM AUTHOR]

This investigation is aimed at modeling the tensile behavior of electrospun polyurethane (PU) membrane. The PU web is produced with different morphologies and the structural parameters are studied through SEM images. Three-dimensional network is simulated using ABAQUS software. Each fibre is modeled as hyperelastic material and each crosslink is modeled as multi point constrain tie. The stress-strain behavior of PU mat is modeled by finite element method, and the effect of fibre diameter, fibre orientation and thickness of web is investigated. The stress-strain curves of networks at three different morphologies are compared with modeling measurements. The model by using third order reduced polynominal as fibre hyperelastic potential energy function shows good agreement with experimental findings which confirm that the tensile behavior of PU web can be explained entirely by microstructure of the network. [ABSTRACT FROM AUTHOR]

In present paper, a point to point optimal path is planned for a mobile manipulator with flexible links and joints. For this purpose, a perfect dynamic modeling is performed for mobile manipulators considering large deformation in links, shear effects, elastic joints, effect of gravitation, and non-holonomic constraints. To study large deformation of links, non-linear relation of displacement-strain and Green's strain tensor are used. Optimal path is planned based on direct methods and applying meta-heuristic optimization methods. In order to get an optimal path profile, maximum load carried by manipulator and minimum transmission time are considered as the objective functions for optimization problem. To provide the parameters of optimization problem, parametric optimization problem is solved by using Harmony Search (HS) and Simulated Annealing (SA) efficient methods. In order to investigate the efficiency of the proposed method, simulation studies are performed considering two-link flexible manipulator with wheeled base. The results indicate that the method proposed has a suitable power and performance when facing dynamics non-linear system. Moreover, the results of path planning for manipulators by small and large deformation models are also compared. The effect of flexibility in joints is studied when planning a point to point path. [ABSTRACT FROM AUTHOR]

In this paper, an elastic modulus reduction (EMR) method is used for the estimation of the creep fracture mechanics parameter C*. The method makes use of uniaxial creep material properties and an appropriate definition of the limiting stresses ahead of the crack tip. Several standard test specimens are selected for analysis. First, the limit load calculations are performed for specimens using the EMR approach and then the C* integral is estimated using the reference stress method. For the limit load analysis of the cracked bodies, a special meshless code has been developed. The results obtained for both limit loads and C* integral are compared with the literature. It is shown that for the present geometries good agreement can be achieved. [ABSTRACT FROM AUTHOR]