Tetsuji Matsuo, Jun Kawahara, Tomohiro Shimoi and Takeshi Mifune
The purpose of this paper is to examine the numerical stability of a space-time finite integration (FI) method. A symmetric correction is proposed to give an accurate constitutive…
Abstract
Purpose
The purpose of this paper is to examine the numerical stability of a space-time finite integration (FI) method. A symmetric correction is proposed to give an accurate constitutive relation at the subgrid connections.
Design/methodology/approach
A scheme for the numerical stability analysis of the space-time FI method is presented, where the growth rate of instability is evaluated by a numerical eigenvalue analysis formulated from an explicit time-marching scheme.
Findings
The 3D and 4D subgrid schemes using the space-time FI method are conditionally stable, where a symmetric correction does not induce numerical instability. The staircase-type 4D space-time subgrid allows a larger time-step than the straight-type subgrid.
Originality/value
The numerical stability of space-time FI method is proven by an eigenvalue analysis, which provides 3D and 4D stable subgrid schemes.
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Keywords
Ru Zhang, Chuanzhen Huang, Jun Wang, Hongtao Zhu and Hanlian Liu
The purpose of this study is to fabricate high-aspect-ratio grooves with high surface quality by femtosecond laser (FS) to improve the machinability of silicon carbide (SiC) and…
Abstract
Purpose
The purpose of this study is to fabricate high-aspect-ratio grooves with high surface quality by femtosecond laser (FS) to improve the machinability of silicon carbide (SiC) and optimize the process parameters in micromechanical applications.
Design/methodology/approach
Four contrast experiments are reported to characterize the FS laser grooving process for SiC with polarization direction, crystal orientation, multi-pass scanning and z layer feed, respectively. The effects of different experimental conditions on the groove characteristics, material removal rate (MRR), aspect ratio, heat affected zone (HAZ) and surface roughness Ra are analyzed.
Findings
The influence of increasing laser fluence and multi-scanning pass on the groove depth is greater than on the groove width. The MRR, aspect ratio, HAZ and Ra increased with the increase of laser fluence and multi-scanning pass. The direction of laser polarization affects the direction of hot electron injection but has little effect on the material characteristics. FS laser ablation is an isotropic process and there is no obvious change in different crystal orientations. The z-layer feed can significantly increase the groove width and depth and reduce HAZ and Ra. The maximum aspect ratio of 82.67% was fabricated.
Originality/value
The results contribute to the understanding of the removal mechanism and reduce the friction of the microfluidic device and improve the flowability in the FS laser ablation of SiC. This paper provides suggestions for the selection of suitable process parameters and provides a wider possibility for the application of micro-texture on SiC.
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The purpose of the method is to develop a numerical method for the solution of nonlinear partial differential equations.
Abstract
Purpose
The purpose of the method is to develop a numerical method for the solution of nonlinear partial differential equations.
Design/methodology/approach
A new numerical approach based on Barycentric Rational interpolation has been used to solve partial differential equations.
Findings
A numerical technique based on barycentric rational interpolation has been developed to investigate numerical simulation of the Burgers’ and Fisher’s equations. Barycentric interpolation is basically a variant of well-known Lagrange polynomial interpolation which is very fast and stable. Using semi-discretization for unknown variable and its derivatives in spatial direction by barycentric rational interpolation, we get a system of ordinary differential equations. This system of ordinary differential equation’s has been solved by applying SSP-RK43 method. To check the efficiency of the method, computed numerical results have been compared with those obtained by existing methods. Barycentric method is able to capture solution behavior at small values of kinematic viscosity for Burgers’ equation.
Originality/value
To the best of the authors’ knowledge, the method is developed for the first time and validity is checked by stability and error analysis.
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Keywords
Carlos Eduardo Díaz, Roemi Fernández, Manuel Armada and Felipe de Jesús García Gutiérrez
– This paper aims to provide an insight into recent advancements and developments of robotics for Natural Orifice Transluminal Surgery (NOTES) procedures.
Abstract
Purpose
This paper aims to provide an insight into recent advancements and developments of robotics for Natural Orifice Transluminal Surgery (NOTES) procedures.
Design/methodology/approach
Following an introduction that highlights the evolution from Minimally Invasive Surgery (MIS) to NOTES in the medical field, this paper reviews the main robotics systems that have been designed and implemented for MIS and NOTES, summarising their advantages and limitations and remarking the technological challenges and the requirements that still should be addressed and fulfilled.
Findings
The state-of-the-art presented in this paper shows that the majority of the platforms created for NOTES are laboratory prototypes, and their performances are still far from being optimal. New solutions are required to solve the problems confronted by the proposed systems such as the limited number of DOFs, the limited resolution, the optimal fixation and stiffening of the instruments for enabling stable and precise operation, the effective transmission of forces to the tip tools, the improvement of the force feedback feeling and the proper visualization and spatial orientation of the surgical field. Advances in robotics can contribute significantly to the development and future implementation of the NOTES procedure.
Originality/value
This paper highlights the current trends and challenges ahead in robotics applied to NOTES procedure.