scholarly journals Multi-objective optimisation of material properties and strut geometry for poly(L-lactic acid) coronary stents using response surface methodology

2019 ◽  
Author(s):  
R.W. Blair ◽  
N.J. Dunne ◽  
A.B. Lennon ◽  
G.H. Menary
Keyword(s):  
Response Surface Methodology ◽  
Lactic Acid ◽  
Response Surface ◽  
Material Properties ◽  
Coronary Stents ◽  
The Body ◽  
Design Parameters ◽  
Metal Stents ◽  
Multi Objective ◽  
Trade Offs

AbstractCoronary stents for treating atherosclerosis are traditionally manufactured from metallic alloys. However, metal stents permanently reside in the body and may trigger undesirable immunological responses. Bioresorbable polymer stents can provide a temporary scaffold that resorbs once the artery heals but are mechanically inferior, requiring thicker struts for equivalent radial support, which may increase thrombosis risk. This study addresses the challenge of designing mechanically effective but sufficiently thin poly(L-lactic acid) stents through a computational approach that optimises material properties and stent geometry. Forty parametric stent designs were generated: cross-sectional area (post-dilation), foreshortening, stent-to-artery ratio and radial collapse pressure were evaluated computationally using finite element analysis. Response surface methodology was used to identify performance trade-offs by formulating relationships between design parameters and response variables. Multi-objective optimisation was used to identify suitable stent designs from approximated Pareto fronts and an optimal design is proposed that offers comparable performance to designs in clinical practice. In summary, a computational framework has been developed that has potential application in the design of high stiffness, thin strut polymeric stents that contend with the performance of their metallic counterparts.

Optimization of Aqueous Two Phase Extraction of Proteins from Litopenaeus Vannamei Waste by Response Surface Methodology Coupled Multi-Objective Genetic Algorithm

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
P. Saravana Pandian ◽  
S. Sindhanai Selvan ◽  
A. Subathira ◽  
S. Saravanan
Keyword(s):  
Genetic Algorithm ◽  
Molecular Weight ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Litopenaeus Vannamei ◽  
Value Added ◽  
Phase System ◽  
Two Phase ◽  
Multi Objective ◽  
Multi Objective Genetic Algorithm

Abstract Waste generated from industrial processing of seafood is an enormous source of commercially valuable proteins. One among the underutilized seafood waste is shrimp waste, which primarily consists of head and carapace. Litopenaeus vannamei (L. vannamei) is the widely cultivated shrimp in Asia and contributes to 90 % of aggregate shrimp production in the world. This work was focused on extraction as well as purification of value-added proteins from L. vannamei waste in a single step aqueous two phase system (ATPS). Polyethylene glycol (PEG) and trisodium citrate system were chosen for the ATPS owing to their adequate partitioning and less toxic nature. Response surface methodology (RSM) was implemented for the optimization of independent process variables such as PEG molecular weight (2000 to 6000), pH (6 to 8) and temperature (25 to 45 °C). The results obtained from RSM were further validated using a Multi-objective genetic algorithm (MGA). At the optimized condition of PEG molecular weight 2000, pH 8 and temperature 35 °C, maximum partition coefficient and protein yield were found to be 2.79 and 92.37 %, respectively. Thus, L. vannamei waste was proved to be rich in proteins, which could be processed industrially through cost-effective non-polluting ATPS extraction, and RSM coupled MGA could be a potential tool for such process optimization.

Dry Sliding Wear Behaviour of Magnesium nanocomposites using Response Surface Methodology

2021 ◽  
pp. 1-18
Author(s):  
Kartheesan S ◽  
B. Shahul hamid Khan ◽  
M Kamaraj ◽  
Manoj Gupta ◽  
Sravya Tekumalla
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Sliding Wear ◽  
Wear Behaviour ◽  
Design Parameters ◽  
Dry Sliding Wear ◽  
Wear Loss ◽  
Sliding Velocity ◽  
Sliding Distance ◽  
Sliding Wear Behaviour

Abstract In this study, a pure magnesium material reinforced with 0.5, 1, 1.5, and 2 weight % of CaO was prepared through disintegrated melt deposition technique. Nanocomposites were investigated for their sliding wear behaviour in dry condition at room temperature. Amount of CaO, Load, sliding distance, and Sliding velocity were selected as input design parameters at their five-level in central composite design using Minitab 18.1 statistical software. The influence of design parameters on wear loss is reported through the Response Surface Methodology (RSM). ANOVA was used to confirm the soundness of the developed regression equation. The results indicate the contribution of linear, quadratic, and interaction terms of design parameters on response. 3D response surface and 2D contour plots are indicated the interaction effect. The result shows that an increase in sliding velocity contributes to a decrease in the wear loss of the composites because of the emergence of protective oxidative layer at the surfaces of the pins, which is confirmed through FESEM and EDAX analysis of the pin surfaces. Wear loss of the material decreased as amount of CaO increased. The ANOVA analysis concluded that the sliding distance and load contribute significantly to wear loss of the composites and their percentage of contribution is 64.02 % and 3.69%.

Multi-objective Optimization of UV Spot Curing Technique of Slider - Suspension Attachment Process Using Response Surface Methodology Approach

2021 ◽  
Author(s):  
Santi Pumkrachang
Keyword(s):  
Response Surface Methodology ◽  
Shear Strength ◽  
Response Surface ◽  
Process Parameters ◽  
Epoxy Adhesive ◽  
Quadratic Model ◽  
Uv Curable ◽  
Multi Objective ◽  
Validation Experiment ◽  
Cure Time

The ultraviolet (UV) curing of slider-suspension attachment is going to change from a manual to an automated process. As a result, the bonding parameters of adhesive between slider and suspension needs to be optimized. This paper aims to study two output responses of the UV curable epoxy adhesive i.e., shear strength force and pitch static attitude (PSA) of the joint between slider and suspension in a head gimbal assembly (HGA). Four process parameters were investigated using response surface methodology (RSM) based on face-centered central composite design (FCCD). The RSM was applied to establish a mathematical model to correlate the significance of process parameters and the responses. Then the based multi-objective was applied to determine a quadratic model and obtained the output maximization at 224 g of shear strength force and PSA value close to the target at 1.8 degrees. The input process parameters were optimized at 0.7 s of UV bottom cure time, 120 °C of UV dual side temperature, 5.0 s of UV dual side cure time, and 230 μm of adhesive dot size. The validation experiment showed a prediction response error of less than 7% of the actual value.

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