Water retention properties of a fused deposition modeling based 3D printed polylactic acid vessel

The applications of fused deposition modelling (FDM) based 3D printing have gone beyond merely simple prototypes to where functionalities are expected. One of such functionalities is the water retention properties, especially for fluid handling products, either completely waterproof or deliberately porous. Issues arise especially in determining crucial parameters and their optimization to achieve the desired water retention properties. This study established the relationship among printing parameters (layer thickness and wall thickness) and water temperature with leakage flow rate. A series of 3D printed polylactic acid (PLA) vessels were fabricated at various layer height and wall thickness. Then, the volumetric loss of water at various temperatures was measured, elapsed time was recorded, and the leakage flow rate was calculated for each 3D printed vessel. It has been found that the leakage flow rate decreased when layer height decreased, wall thickness increased, and water temperature decreased. Based on multilinear regression analysis, the magnitude of influence for the layer height was the highest, which could reach at a point where variation in wall thickness and water temperature had no effect. A regression model having 81.27% fitness that provided a quantitative relationship among all parameters had also been obtained. ANOVA analysis revealed that all parameters were statistically significant in optimizing as well as predicting the value of the leakage flow rate

Fish harvesting management strategies using logistic growth model (Strategi Pengurusan Penuaian Ikan dengan Menggunakan Model Pertumbuhan Logistik)

This paper studies the harvesting strategies for tilapia fish farming. Two logistic growth models have been used namely constant harvesting and periodic harvesting. Even though tilapia fish farming has been commercialized, the use of mathematical models in determining harvesting strategies has not been widely applied in Malaysia. Logistic growth model is appropriate for population growth of animal when overcrowding and competition resources are taken into consideration. The objectives of this study were to estimate the highest continuing yield from fish harvesting strategies implemented. Secondly, the study predicted the optimum quantity for harvesting that can ensure the tilapia fish supply is continuous. Finally, to compare the results obtained between the two strategies. The best harvesting strategy for the selected fish farm is periodic harvesting. These findings can assist fish farmers to increase the supply to meet the demand for tilapia fish

A preference analysis of renewable energy alternatives in Malaysia using fuzzy VIKOR method

In Malaysia, the main consumed energy is the fossil fuel. As the population continues to increase and the fossil fuels begin to deplete rapidly, it may not be possible to depend solely on fossil fuel. A feasible alternative should be sought to replace the dependency of the fossil fuel. In this paper, an evaluation is made on the experts’ preference of the type of eco-friendly renewable energy that is suitable to be used in Malaysia between biomass, solar, hydro or hybrid energy using the fuzzy VIKOR method. Since the evaluation considers subjective element that involves human perceptions and knowledge experts, the Fuzzy VIKOR method is considered to be an appropriate choice. The Fuzzy VIKOR method has the ability to deal with multi-conflicting or non-commensurable criteria in the ranking and selecting the alternatives. The evaluation is based on four main criteria which are Efficiency, Operation, Land Use and Job Creation of each alternative. It is found that the main concern of the renewable energy choice is on its efficiency and the hydro energy is the most preferred alternative energy to be used in Malaysia

Extended FTOPSIS with Distance and Set Theoretic-Based Similarity Measure

Comparing fuzzy numbers is an essential process in deducing the output of many fuzzy decision making methods. One of the comparison methods commonly used is by using similarity measure. The main advantage of the similarity measure over other approaches is its ability to minimize the loss of information in the computational process. Several similarity measures have been applied effectively in fuzzy decision making methods. In this paper, a new similarity measure based on the geometric distance, the center of gravity, Hausdorf distance and the set theoretic similarity formula known as the Dice similarity index are incorporated into the Extended Fuzzy Technique for Order Preference by Similarity to Ideal Solution (FTOPSIS) method particularly in calculating the closeness coefficients. This similarity measure is in favor of others as it is able to discriminate two similar shape fuzzy numbers effectively with two different locations. A validation process is carried out by implementing the proposed procedure of the Extended FTOPSIS with the new similarity measure in solving a supplier selection problem and the ranking outcome is then compared with the Extended FTOPSIS with other existing similarity measure. The result shows that the Extended FTOPSIS with the proposed similarity measure gives a consistent result without reducing any information in the computational process