Accurate prediction of the friction factor and consequently the pressure drop of two-phase flow in small channels is still an issue. Many correlations exist for the determination of the viscosity and the friction fact...
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Accurate prediction of the friction factor and consequently the pressure drop of two-phase flow in small channels is still an issue. Many correlations exist for the determination of the viscosity and the friction factor that appear in the frictional pressure drop and their combination often determined the degree of disagreements between the experimental data and predicted outcomes. Demands for environmentally friendly refrigerants have further posed a challenge to find compatible alternatives with as good a performance as the current coolants. Despite the many available correlations developed to date, many more are studied in effort to reduce the discrepancies. This paper presents the outcomes of a study comparing the optimized conditions when three different viscosity equations are paired with eight different friction factor correlations to minimize the frictional pressure drop. The approach used multi-objective genetic algorithm (MOGA) to assist in selecting the best pairing. Comparison is then completed with available experimental data. The study showed that the Blasius friction factor paired with the Dukler viscosity produced the least percentage difference for R22, while when paired with the McAdams viscosity produced a lower difference for R290, an environmentally friendly refrigerant being considered to replace R22.
An inverted pendulum system (IPS) is a highly nonlinear dynamical open loop unstable system, typically used as a benchmark to verify the performance of controllers. The IPS emulates the behaviour of an altitude contro...
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An inverted pendulum system (IPS) is a highly nonlinear dynamical open loop unstable system, typically used as a benchmark to verify the performance of controllers. The IPS emulates the behaviour of an altitude control of a space booster or rocket on take-off. The problem is to develop suitable controllers to maintain the stabilization and swing up of an inverted pendulum on a cart. This paper presents the evolutionary tuning methods of nonlinear PID (NL-PID) controller for IPS with the multi-objective genetic algorithm (MOGA) and adaptive particle swarm optimization (APSO) algorithm. The function of NL-PID controllers is to keep the pendulum in an upright position by maintaining the pendulum at same state and angle at zero degrees. The comparison of responses and performance of MOGA tuned NL-PID and APSO tuned NL-PID controllers for an IPS are described. The mathematical modeling and simulation analysis of the IPS is presented in detail to test the effectiveness of controller tuning algorithm. The APSO based tuning of the NL-PID controller has lesser chattering, noise and fast settling time than MOGA based tuning of the controller.
The multi-objective Job-Shop scheduling problem under multi-resource constrains was investigated and the active heuristic based operation precedence was developed to address the minimization of makespan, the minimizat...
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The multi-objective Job-Shop scheduling problem under multi-resource constrains was investigated and the active heuristic based operation precedence was developed to address the minimization of makespan, the minimization of total tardiness and the minimization of total idle time of the machines. Then a hybrid procedure was presented by combining the heuristic with multi-objective genetic algorithms and fuzzy evaluation. In the procedure, the representation based operation and the crossover operator based heuristics were adopted, which lead to chromosomes evolve in the active scheduling domain. The weights, which were specified randomly for each fuzzy evaluation, ensured the multidirectional search in the multi-objective genetic algorithm. The results of examples show that the procedure is available and efficient, and superior to the method of Ponnambala.
This paper contains a strategy to minimize energy losses in an electrical distribution network. In order to develop the strategy, a model was constructed to simulate an electrical distribution network, and different p...
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ISBN:
(纸本)9781629931333
This paper contains a strategy to minimize energy losses in an electrical distribution network. In order to develop the strategy, a model was constructed to simulate an electrical distribution network, and different parameters were included that help in estimation of technical losses in medium voltage (MV) distribution network. The main objective of this paper is to minimize technical and non-technical losses in power systems. There are losses in power systems that cannot be predicted or calculated beforehand, these are the non-technical losses. The bulk of these losses are likely caused by electricity theft, rather than the other possibilities such as poor maintenance of meters, and calculation and accounting mistakes, some power systems may suffer from both. The strategy is applied on a part of real distribution network. The network segments consist of different network busses delivering electrical energy from substation to supply different customers. In this network, the load supplied by one bus is a varying load for different times especially at maximum load conditions.
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