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Full-Text Articles in Engineering
Multiple-Objective Optimization In Precision Laser Cutting Of Different Thermoplastics
Multiple-Objective Optimization In Precision Laser Cutting Of Different Thermoplastics
Faculty of Engineering University of Malaya
Thermoplastics are increasingly being used in biomedical, automotive and electronics industries due to their excellent physical and chemical properties. Due to the localized and non-contact process, use of lasers for cutting could result in precise cut with small heat-affected zone (HAZ). Precision laser cutting involving various materials is important in high-volume manufacturing processes to minimize operational cost, error reduction and improve product quality. This study uses grey relational analysis to determine a single optimized set of cutting parameters for three different thermoplastics. The set of the optimized processing parameters is determined based on the highest relational grade and was found …
Cutting Force-Based Adaptive Neuro-Fuzzy Approach For Accurate Surface Roughness Prediction In End Milling Operation For Intelligent Machining
Faculty of Engineering University of Malaya
End milling is one of the most common metal removal operations encountered in industrial processes. Product quality is a critical issue as it plays a vital role in how products perform and is also a factor with great influence on manufacturing cost. Surface roughness usually serves as an indicator of product quality. During cutting, surface roughness measurement is impossible as the cutting tool is engaged with the workpiece, chip and cutting fluid. However, cutting force measurement is easier and could be used as an indirect parameter to predict surface roughness. In this research work, a correlation analysis was initially performed …
Modeling The Polyphenoloxidase Inactivation Kinetics In Pear, Apple And Strawberry Purees After High Pressure Processing
Faculty of Engineering University of Malaya
High Pressure Processing of Royal Gala apple, Taylor's Gold pear and Camarosa strawberry purees was carried out to inactivate polyphenoloxidase (PPO). First, 600 MPa enzyme inactivation at room temperature was investigated. After 60 min, strawberry (8% RA, residual activity) and apple (89% RA) PPOs were partially inactivated and pear PPO was not inactivated, demonstrating the high variability in the resistance of different fruits' PPOs. Then, the fruit purees were submitted to 600 MPa combined with mild heat, and the PPO inactivation kinetics was modeled. The pear PPO was found to be resistant even after 60 min 600 MPa-71 degrees C …
Model Predictive Control Of Bidirectional Ac-Dc Converter For Energy Storage System
Model Predictive Control Of Bidirectional Ac-Dc Converter For Energy Storage System
Faculty of Engineering University of Malaya
Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected …
Stability And Performance Investigations Of Model Predictive Controlled Active-Front-End (Afe) Rectifiers For Energy Storage Systems
Faculty of Engineering University of Malaya
This paper investigates the stability and performance of model predictive controlled active-front-end (AFE) rectifiers for energy storage systems, which has been increasingly applied in power distribution sectors and in renewable energy sources to ensure an uninten-uptable power supply. The model predictive control (MPC) algorithm utilizes the discrete behavior of power converters to determine appropriate switching states by defining a cost function. The stability of the MPC algorithm is analyzed with the discrete z-domain response and the nonlinear simulation model. The results confirms that the control method of the active-front-end (AFE) rectifier is stable, and that is operates with an infmite …