Four global optimisation algorithms are applied in the design optimisation of a hybrid electric vehicle (HEV). These four algorithms are: DIRECT, Simulated Annealing, Genetic algorithm, and Particle Swarm optimisation...
详细信息
Four global optimisation algorithms are applied in the design optimisation of a hybrid electric vehicle (HEV). These four algorithms are: DIRECT, Simulated Annealing, Genetic algorithm, and Particle Swarm optimisation. The optimisation objective is to achieve maximum fuel economy, subject to the constraints of vehicle performance. The model in the loop methodology is adopted for our design process, in which a vehicle model named PSAT is used as the analysis tool. The design optimisation results and the performance of the four optimisationalgorithms are compared. Our initial study shows that DIRECT and Simulated Annealing algorithms are efficient for the complex HEV engineering design problem.
Phase-only synthesis (POS) techniques represent an important tool for reflectarray design. Indeed, although based on approximate scattering models, for planar antennas, they are numerically effective thanks to the use...
详细信息
Phase-only synthesis (POS) techniques represent an important tool for reflectarray design. Indeed, although based on approximate scattering models, for planar antennas, they are numerically effective thanks to the use of fast Fourier transform (FFT) routines. Conformal reflectarrays are becoming of interest as they reduce the frequency dependence of the feed/elements path length. Although synthesis algorithms can be extended from planar to conformal geometries, improving computational efficiency is not trivial. We present a POS, power pattern synthesis technique of conformal, shaped-beam reflectarrays, based on the p-series approach, on non-uniform FFTs, and on fast implementations of the FFT and of matrix-vector and vector-vector multiplications. The approach allows modulating computational burden and accuracy, depending on the needs. The method faces crucial issues concerning the reliability of the solution, by adopting a multi-step strategy. At first, the unknown phase shifts are represented by few degrees of freedom and an efficient and effective global optimisation algorithm is applied. Then, assuming as a starting point the obtained solution, all the reflectarray degrees of freedom are taken into account. The computational performance of the approach and its capability in synthesising shaped-beam patterns are discussed against parabolic and faceted reflectarrays, also considering the coverage of an operative mission.
Characteristic mode analysis has proven useful in the design of multi-input multi-output antennas. By identifying characteristic current modes associated with a conductive structure, the designer can place ports to re...
详细信息
Characteristic mode analysis has proven useful in the design of multi-input multi-output antennas. By identifying characteristic current modes associated with a conductive structure, the designer can place ports to replicate those current modes, which should generate orthogonal far fields with high isolation from one another. An algorithm that uses characteristic mode analysis is proposed to synthesise multi-input multi-output antennas from a conductive structure by determining port placement and excitations without visual inspection. Our algorithm uses a correlation metric to determine the proper excitation from a particular port, and uses a global optimisation algorithm to determine the optimal port placement. Given a particular structure and a domain of possible port locations, our algorithm places ports and generates excitations to synthesise the desired multi-input multi-output antenna. Our algorithm is used to synthesise and simulate a simple 3D cell phone model with a metal ground plane, metal rim, and dielectric. The result is an antenna with the desired six isolated channels at 2.5 GHz.
Vehicle aerodynamic shape optimisation is a typical non-linear and computationally expensive black box problem, which is severely limited by time and cost of the objective function evaluations during the global optimi...
详细信息
Vehicle aerodynamic shape optimisation is a typical non-linear and computationally expensive black box problem, which is severely limited by time and cost of the objective function evaluations during the globaloptimisation process. To solve the shortcomings of low efficiency and high cost of the existing vehicle drag reduction method, an improved efficient globaloptimisation (EGO) algorithm is used to optimise a four-dimensional aerodynamic drag reduction design of a vehicle combined with computational fluid dynamics numerical simulation technology. Moreover, data mining technologies are used to reveal the influence mechanisms of design variables on aerodynamic drag and to analyse the relationship between the variables. It is demonstrated that the improved EGO algorithm, based on the kriging response surface and expected improvement function, can achieve the global optimum with minimum function evaluations. The aerodynamic drag of the optimal design is 1.56% lower than that of the original vehicle. The data mining results showed that the engine hood inclination and the tail upturn angle play a leading role in the vehicle's aerodynamic drag, and the hood inclination has the greatest impact.
暂无评论