Squids-snapper fish dynamics model with fishing effects in Terengganu, Malaysia

Overexploitation of marine resources by human activities has become a pandemic issue nowadays. High fishing rates for example, may lead to the extinction of marine populations. In this paper, we introduce a mathematical model of prey-predator system for marine ecosystem with fishing rates for the case of Terengganu state. For this model, we use squids as prey while snapper fish as predator. The objectives of this paper are to analyze the sustainability of equilibrium populations of squids and snapper fish using stability analysis and to show the effect of fishing rates on both of these populations. This model shows that there are four potential equilibria solutions where both populations of squids and snapper fish may be extinct, mutual exclusions where either one of the species dies out as well as coexistence of both populations. The results for stability analysis reported that the equilibrium of coexistence of both populations was stable while the other was unstable. This means that populations of squids and snapper fish are estimated to sustain in the future with the current fishing activities in Terengganu. Hence, we conjectured that in order to guarantee both populations continue to exist, the fishing activities in Terengganu must be restricted within certain range of parameters that is lower than the population growth rates

Optimization of PID Parameters Utilizing Variable Weight Grey-Taguchi Method and Particle Swarm Optimization

Controller that uses PID parameters requires a good tuning method in order to improve the control system performance. Tuning PID control method is divided into two namely the classical methods and the methods of artificial intelligence. Particle swarm optimization algorithm (PSO) is one of the artificial intelligence methods. Previously, researchers had integrated PSO algorithms in the PID parameter tuning process. This research aims to improve the PSO-PID tuning algorithms by integrating the tuning process with the Variable Weight Grey-Taguchi Design of Experiment (DOE) method. This is done by conducting the DOE on the two PSO optimizing parameters: the particle velocity limit and the weight distribution factor. Computer simulations and physical experiments were conducted by using the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE and the classical Ziegler-Nichols methods. They are implemented on the hydraulic positioning system. Simulation results show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE has reduced the rise time by 48.13% and settling time by 48.57% compared to the Ziegler-Nichols method. Furthermore, the physical experiment results also show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE tuning method responds better than Ziegler-Nichols tuning. In conclusion, this research has improved the PSO-PID parameter by applying the PSO-PID algorithm together with the Variable Weight Grey-Taguchi DOE method as a tuning method in the hydraulic positioning system

Modification of structure and properties of well-dispersed dendrimer coated multi-walled carbon nanotube reinforced polyester nanocomposites

This work reveals the structure and properties of dendrimer coated multiwall carbon nanotube (DMWCNT) reinforced unsaturated polyester resin (UPR) nanocomposite. Rheology, as well as the shear thinning behavior of nanosuspension exhibits the dispersion of DMWCNT in UPR matrix. The Raman spectra of DMWCNT-UPR nanocomposites along with the Fourier-transform infrared (FTIR) spectra of DMWCNT and DMWCNT-UPR nanocomposites indicate the interaction between DMWCNT and UPR in the nanocomposite system. Additionally, the surface morphology of DMWCNT and DMWCNT-UPR nanocomposites reveals well dispersion of DMWCNT in DMWCNT-UPR nanocomposites. X-ray diffraction (XRD) profile demonstrates structural properties of pristine UPR and nanocomposites. The Transmission Electron micrograph and Field Emission Scanning Electron micrograph show the fractured surface morphologies of DMWCNT-UPR nanocomposites. Comparative stress-strain behavior shows the deformation mechanism of DMWCNT-UPR nanocomposites

Increasing the Efficiency of Traveling Wave Ultrasonic Motor by Modifying the Stator Geometry

Current traveling wave ultrasonic motor (TWUSM) utilizes comb-teeth structure as deflection amplifier. The position of the stator neutral axis to the stator contact surface is one of the factors that influences the deflection amplifier. Stator deflection directly effects on motor performance. In this study, the modification of the comb-teeth stator design is proposed to see its effect on motor efficiency. The modification is done so that the neutral axis position is further distance from the stator top contact surface. The proposed solution is to remove a selected mass element from the comb-teeth structure. Modeling, simulation and experimental work of the proposed concept is carried out utilizing Shinsei USR60 as the chosen TWUSM. The modeling and analyses are conducted through multi-physic finite element simulation MSC Marc Mentat. The results of the analyses and experimental work reveal that the modified comb-teeth stator increases the position of the neutral axis from the stator top surface. Due to the neutral axis shifting, the results also confirm that the proposed modified motor has higher efficiency compared to the non-modified motor

Polylactic acid(pla)/acrylonitrile butadiene styrene(ABS) nanocomposites with hybrid graphene/ montmorillonite (MMT)

Poly(lactic acid) is widely used as an environmental friendly polymer that benign to the environment. However, PLA is too brittle to be processed industrially and toughness modification is generally required. In this work, PLA was blended with acrylonitrile butadiene styrene (ABS) and graphene nanoplatelet (GnP) / MMT nanofillers were incorporated in PLA/ABS blends sytem. Melt compounding was carried out in a twin screw extruder with 50 rpm for 15 minutes at temperatures between 160-200 oC. The PLA/ABS and PLA/ABS/GnP/MMT blend systems were characterized for mechanical, thermal, chemical and morphological properties. It was found that the mechanical properties of PLA/ABS/GnP/MMT has improved as compared to PLA/ABS blend. Morphology analysis showed that the mechanical properties improvement could be attributed due to the presence of smaller voids in PLA/ABS/GnP/MMT blend. There were no significant chemical changes on the PLA/ABS and PLA/ABS/GnP/MMT blend systems as revealed by the FTIR spectra

Pso-based PID speed control of traveling wave ultrasonic motor under temperature disturbance

Traveling wave ultrasonic motors (TWUSMs) have a time varying dynamics characteristics. Temperature rise in TWUSMs remains a problem particularly in sustaining optimum speed performance. In this study, a PID controller is used to control the speed of TWUSM under temperature disturbance. Prior to developing the controller, a linear approximation model which relates the speed to the temperature is developed based on the experimental data. Two tuning methods are used to determine PID parameters: conventional Ziegler-Nichols(ZN) and particle swarm optimization (PSO). The comparison of speed control performance between PSO-PID and ZN-PID is presented. Modelling, simulation and experimental work is carried out utilizing Fukoku-Shinsei USR60 as the chosen TWUSM. The results of the analyses and experimental work reveal that PID tuning using PSO-based optimization has the advantage over the conventional Ziegler-Nichols method