Centrifugal compressors are required to increase their operating range and efficiency, which are limited at low mass flow rates by the rotating stall and surge. This paper presents a surrogate-based multi-objective op...
详细信息
Centrifugal compressors are required to increase their operating range and efficiency, which are limited at low mass flow rates by the rotating stall and surge. This paper presents a surrogate-based multi-objective optimization of a centrifugal compressor to improve its efficiency and stall margin. Curvatures of the blade, the impeller shroud, and the diffuser hub are selected as optimization parameters since they influence highly both the efficiency and the stall limit. The implemented optimization procedure starts by the construction of a metamodel, which is the radial basis function that uses a database composed of a well-selected set of geometries and their corresponding computational fluid dynamics predicted objectives using the Ansys-CFX 12 code. The NSGA-II optimization algorithm is used afterward to search the Pareto front based on radial basis function approximations. To improve the accuracy of the radial basis function and subsequently the Pareto front, a database refinement is sequentially achieved, using the leave-one-out-cross-validation uncertainty to select infill points. The present procedure is tested on the NASA low-speed centrifugal compressor, showing its ability to increase both the compressor operating range and efficiency. Furthermore, the flow pattern analysis confirms the suppression of separations that lead to instability in the optimized compressor at the stall point of the baseline design.
This paper presents a particle swarm optimization network (PSON) to improve the search capability of PSO. In PSON, multi-PSOs are connected for the purpose of communication. A variety of network topology can be realiz...
详细信息
This paper presents a particle swarm optimization network (PSON) to improve the search capability of PSO. In PSON, multi-PSOs are connected for the purpose of communication. A variety of network topology can be realized by varying the number of connected PSOs of each PSO. The solving performance and convergence speed can be controlled by changing the network topology. Furthermore, high parallelism is can be realized by assigning PSO to single processor. The stability condition analysis and performance of PSON are shown.
Here, we theoretically suggest the possibility of optical cloaking by employing the binary optimization of plasmonic nano-bi-dome. The proposed cloaking mechanism is based on reducing the total scattering coefficient ...
详细信息
Here, we theoretically suggest the possibility of optical cloaking by employing the binary optimization of plasmonic nano-bi-dome. The proposed cloaking mechanism is based on reducing the total scattering coefficient in optical frequency. Since the scattering coefficient depends strongly on the number of plasmonic nano-particles and the nano particles location, binary particle swarm optimization (BPSO) algorithm is proposed to design an optimized array of the plasmonic nano-bi-domes in order to achieve the minimum scattering coefficient in the optical frequency. In BPSO, a swarm consists of a matrix with binary entries, control the presence ('1') or the absence ('0') of nano bi-domes in the array.
Using particle swarm optimization method, an optimized gain ripple was found for two-sided coupled integrated spaced sequence of Si and Si1-xGex microring resonator Raman amplifier. This amplifier had two sides of rin...
详细信息
Using particle swarm optimization method, an optimized gain ripple was found for two-sided coupled integrated spaced sequence of Si and Si1-xGex microring resonator Raman amplifier. This amplifier had two sides of ring resonators, each consisting of eight rings. On the one side, the microrings were made of Si, and on the other, they were constructed from microSiGe rings. Resonance frequencies of a ring in Si row were equal to those of a ring in the SiGe row;therefore, for a ring of the first row and a ring of the second row, only one pump was used.
The electric multiple unit (EMU) is a complex system running in dynamic environments. Satisfaction on real-time manual operation strategy of the EMU with respect to the multi-objective operation demands, including sec...
详细信息
The electric multiple unit (EMU) is a complex system running in dynamic environments. Satisfaction on real-time manual operation strategy of the EMU with respect to the multi-objective operation demands, including security, punctuality, accurate train parking, energy saving and ride comfort, depends on the drivers' experience and a given V-S curve (velocity versus position curve). To improve the operation strategy, a multi-objective optimization model of EMU operation is developed on the basis of dynamic analysis and speed restriction mutation. Using a modified particle swarm optimization algorithm, a Pareto optimal solution set is obtained by the online optimization of the EMU's operation strategy. Finally, according to the preference order ranking, an optimal operation strategy is sorted out from the Pareto set which satisfies the multi-objective requirements in real time. Experimental results on the field data of CRH380AL (China's railway high-speed EMU type-380AL) demonstrate the effectiveness of the proposed approach. (C) 2015 Elsevier B.V. All rights reserved.
For coherent MIMO radar the optimal target signal processing can be achieved for any transmitted waveforms or radiation beam pattern, making transmit beamforming through waveform design possible without degrading targ...
详细信息
For coherent MIMO radar the optimal target signal processing can be achieved for any transmitted waveforms or radiation beam pattern, making transmit beamforming through waveform design possible without degrading target detection performance. In this work, an innovative waveform optimization approach termed phase-only variable metric method (POVMM) is proposed for coherent MIMO radar waveform design to form a desired transmit beam pattern such as one with radiation nulls in certain directions. The waveform design is carried out by minimizing the radiation powers of the MIMO radar antenna in the selected directions with optimization variables constrained to the waveform phases only. The gradient function of the cost function with regard to waveform phases is analytically derived for the optimization and the POVMM is developed based on the variable metric methods with a flexible search step sizing strategy for improving optimization efficiency. The proposed approach is validated with various designs and simulations.
In this paper, in order to achieve more coupling between photonic crystal waveguide (PCW) and photonic devices, we have used a new optimization method to create output focused beams. The PCW terminated with coupled re...
详细信息
In this paper, in order to achieve more coupling between photonic crystal waveguide (PCW) and photonic devices, we have used a new optimization method to create output focused beams. The PCW terminated with coupled resonator optical waveguide (CROW) is analyzed by the finite difference time domain (FDTD) method. We have optimized the rods of CROW one by one in a special sequence. Our proposed method is more reliable and much faster than other optimization methods such as particle swarm optimization (PSO) and genetic algorithms. The optimized structure compared to the non-optimized one has a factor of 4.73 times improvement in the intensity of the PCW output main lobe. (C) 2014 Elsevier GmbH. All rights reserved.
To describe the continuous bioconversion of glycerol to 1,3-propanediol concerning the intracellular and extracellular dynamics and the transports across cell membrane, we establish a nonlinear switching system and di...
详细信息
To describe the continuous bioconversion of glycerol to 1,3-propanediol concerning the intracellular and extracellular dynamics and the transports across cell membrane, we establish a nonlinear switching system and discuss its some basic properties. For this over parameterized dynamical system, we propose a two-phase method to determine its parameters. The first phase carries out parametric sensitivity analysis for the purpose of reducing the number of the unknown parameters and the second phase covers the optimization of those parameters with higher sensitivity index. Numerical calculations on the basis of multi-groups experiments indicate that the proposed switching system is appropriate and the developed methods are valid. (C) 2014 Elsevier Inc. All rights reserved.
Hong Kong South China Morning network according to *** of statistics said: China of flights delays most serious, according to this problem, paper proposed has a optimization flights of scheduling optimization algorith...
详细信息
Hong Kong South China Morning network according to *** of statistics said: China of flights delays most serious, according to this problem, paper proposed has a optimization flights of scheduling optimization algorithm. Taking a certain period of time and a certain airport as the research object, according to reality, subjecting to some conditions, reasonable arrangements flights, making flights delays time reached minimum, last obtained for this airport of most reasonable of flights arrangements. In the process of solving the model, as in the target weight of another, greatly simplifies the process and reduces the amount of computation. lastly, we chose an airport for example, delay time reduction is obtained using the model
The present paper aims at defining a simplified but effective model of a thermal network that links the thermal power generation with the resulting temperature time profile in a heated or refrigerated environment. For...
详细信息
The present paper aims at defining a simplified but effective model of a thermal network that links the thermal power generation with the resulting temperature time profile in a heated or refrigerated environment. For this purpose, an equivalent electric circuit is proposed together with an experimental procedure to evaluate its input parameters. The paper also highlights the simplicity of implementation of the proposed model into a microgrid Energy Management System. This allows the optimal operation of the thermal network to be achieved on the basis of available data (desired temperature profile) instead of a less realistic basis (such as the desired thermal power profile). The validation of the proposed model is performed on the Savona Campus Smart Polygeneration Microgrid (SPM) with the following steps: (i) identification of the parameters involved in the equivalent circuit (performed by minimizing the difference between the temperature profile, as calculated with the proposed model, and the measured one in a set of training days);(ii) test of the model accuracy on a set of testing days (comparing the measured temperature profiles with the calculated ones);(iii) implementation of the model into an Energy Management System in order to optimize the thermal generation starting from a desired temperature hourly profile.
暂无评论