Multi-objective optimization of thermal and flow characteristics of R-404A evaporation through corrugated tubes

To improve the flow characteristics of tandem cascades on design and off design incidence angle and increase the stable operation range, a multi-objective optimization methodology based on CO-kriging and parallel multi-point sampling strategy is presented to realize multi-objective optimization of tandem cascades. Co-kriging model created by a greater quantity of low-fidelity samples coupled with a small amount of high-fidelity samples is introduced to reduce the compute cost of multi-objective optimization problems. The prediction performances of Co-kriging are much better than those of Kriging based on two numerical examples. The multi-point sampling strategy based on the fuzzy c-means clustering method can realize a good balance between exploitation known regions and exploration unknown regions for selecting new samples to update the Co-kriging. And the multi-objective optimization methodology can obtain the approximate Pareto frontier at a less compute cost and was validated by applying it to achieve the multi-objective optimization of a high-turning tandem cascade. After optimization, for the optimal tandem cascade, the static pressure ratio is higher and the total pressure loss coefficient is smaller at all incidence angle conditions. At inlet Mach number of 0.7, when incidence angle is −6° and 3°, the total pressure loss coefficient is respectively decreased by 21% and 35%. Tandem cascades with a high PP (about 0.92) and a negative KBB (about −6°) can realize good flow performances on design and off design incidence angle. And a large TR can improve the flow characteristics of tandem cascades on design and off design incidence angle and increase the stable operation range.

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Multi-Objective Optimization Model for Urban Traffic Intersection Control Based on Data Fusion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.156-157.505 ◽

2010 ◽

Vol 156-157 ◽

pp. 505-510 ◽

Cited By ~ 1

Author(s):

Wen Deng ◽

Li Min Jia ◽

Hong Hui Dong

Keyword(s):

Data Fusion ◽

Traffic Flow ◽

Flow Characteristics ◽

Urban Traffic ◽

Traffic Signal Control ◽

Multi Objective Optimization ◽

Equilibrium Degree ◽

Multi Objective ◽

Traffic Intersection ◽

Saturated Traffic

A new multi-objective optimization control strategy for urban intersection is proposed, which takes the degree of smooth and the degree of equilibrium as objectives. The new method is not limited to the traditional basic traffic parameters, such as delay and queue length.etc, but Applying data fusion technology, by multiple integrating on the basic traffic parameters, the real-time multi-objective values are achieved. The degree of the smooth quantitatively denotes the forced travel time extension because of traffic signal control, saturated traffic flow.ect. The degree of equilibrium denotes the equilibrium degree of traffic flow in space. Illustrating an intersection in Beijing, a simulation model in Paramics is built. The simulation results show that the proposed multi-objective control methods can not only reduce the traffic flow delay, but also makes traffic flow distributing equilibrium in each phase of intersection. This approach is consistent with Chinese saturated traffic flow characteristics.

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