The key to the suppression of vibration and noise for PMSM is the optimization of electromagnetic excitation force. The method of motor body optimization can effectively reduce the radial excitation force of the motor...
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The key to the suppression of vibration and noise for PMSM is the optimization of electromagnetic excitation force. The method of motor body optimization can effectively reduce the radial excitation force of the motor, so as to suppress the vibration and noise of the motor. Firstly, the stator structure of the motor is optimized with V-shape skew slot based on the analytical modeling of the radial electromagnetic excitation force of the motor. Then, the structural parameters of the motor that affect the electromagnetic excitation force of the motor are determined, and the average torque, torque ripple and radial electromagnetic excitation force generated by tangential electromagnetic excitation force are taken as the optimization objectives. The sensitivity analysis and classification of the structural parameters of the motor are carried out. The multi -objective geneticalgorithm and response surface method are combined to optimize the structural parameters of the motor. Finally, the finite element analysis, modal analysis, multi -speed vibration and noise analysis of the optimized motor are done. The performance comparisons before and after optimization have proved that the peak of equivalent sound power level have decreased by 8.65% after the optimization of V-shaped skewed slot structure. After the optimization of structural parameters, the power level of permanent magnet synchronous motor has been reduced by 9.22%. For the vibration noise caused by resonance and the main frequency of vibration noise harmonics, the suppression effects are also better than those of Vshape skewed slots optimization, and the ERPL values are reduced by 9.22% and 10.12%, respectively, in two cases. The results show that the vibration and noise of permanent magnet synchronous motor are effectively suppressed.
This paper proposes a novel approach to pricing of American put option under double Heston model. We develop an analytical solution to the double Heston partial differential equation (double Heston PDE) using the equi...
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This paper proposes a novel approach to pricing of American put option under double Heston model. We develop an analytical solution to the double Heston partial differential equation (double Heston PDE) using the equivalent European put option price and standard portfolio-consumption model. Then through the affine form of the model and Fourier transform method, we evaluate the American put option price. Finally, we calibrate the option prices resulting from double Heston model to a set of observed index options by employing genetic optimization algorithm. A detailed numerical study illustrates the efficiency of the proposed method. (C) 2021 Elsevier B.V. All rights reserved.
Magnetorheological (MR) gel is a novel type of smart material with field-dependent rheological properties, which is mainly composited of soft magnetic particles and a gel-like matrix. Its controllable rheological beha...
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Magnetorheological (MR) gel is a novel type of smart material with field-dependent rheological properties, which is mainly composited of soft magnetic particles and a gel-like matrix. Its controllable rheological behaviors depend on many factors, in which temperature is a significant factor requiring further study. Herein, polyurethane-based MR gel with a 60% weight fraction of carbonyl iron is developed. The influence of temperature on the rheological characteristics of the MR gel sample is systematically investigated. The steady shear test is adopted to determine the yield stress and dynamic viscosity of MR gel under different temperatures. A new stress model based on Bingham constitutive model and Arrhenius relation is proposed to incorporate the influence of the temperature and to capture the hysteresis characteristics and strain stiffening properties. The results show that yield stress shows exponential decay with temperature and at the same time, dynamic viscosity displays exponential decay both along with temperature and current. Finally, hysteresis behavior responses by sinusoidal strain excitation with the frequency of 0.1, 5, and 15 Hz at the fixed amplitude of 50% and current of 2 A have been extracted to analyze the impact of temperature on the damping and stiffness properties of the MR gel.
Phononic crystals (PnCs) with a broad bandgap have been the subject of extensive research, particularly for their capacity to manipulate elastic waves efficiently. However, the explored design space remains relatively...
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Phononic crystals (PnCs) with a broad bandgap have been the subject of extensive research, particularly for their capacity to manipulate elastic waves efficiently. However, the explored design space remains relatively limited, and the shapes under consideration are often relatively simple. This study optimizes a free-form hole shape for square and hexagonal lattice aluminum plate PnCs with high relative bandgaps (i.e., ratio of bandgap to its center frequency). optimization is implemented by leveraging the predictive capabilities of deep neural networks (DNNs). For both types of lattices, an initial training dataset is made up of 20,000 randomly generated PnCs unit cells, each containing a symmetric smooth hole. The relative bandgap is subsequently evaluated using the Finite Element Method (FEM). For each lattice, one Deep Neural Network (DNN) is trained to predict the relative bandgap, while another DNN is used to classify whether the bandgap exists. The predictive power of DNNs is exploited to search for design candidates with high relative bandgaps using the genetic optimization algorithm (GOA). The relative bandgaps of new candidates are determined and validated using FEM. The results of these analyses are then utilized to update the DNNs through active learning (AL) techniques. As a result, the relative bandgaps of the progressively refined hole shapes for square and hexagonal lattices are 2.382 and 10.383 times larger, respectively, than those of circular holes.
This paper approaches the design using two optimization techniques for a permanent magnet generator used in a micro-wind turbine, with a major importance on the overall performances of the energy conversion system. Th...
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ISBN:
(纸本)9781538623442
This paper approaches the design using two optimization techniques for a permanent magnet generator used in a micro-wind turbine, with a major importance on the overall performances of the energy conversion system. The proposed micro-wind generator has two armatures and both are rotating in opposite directions.
Owing to the many unknown parameters and complex overlying stratums structure evolution, the back analysis of the dynamic deformation is becoming a typical complex nonlinear optimization *** order to overcome the low ...
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Owing to the many unknown parameters and complex overlying stratums structure evolution, the back analysis of the dynamic deformation is becoming a typical complex nonlinear optimization *** order to overcome the low efficiency of the conventional inversion method in multi-parameters back analysis,firstly, using the strata control theory to analyze the dynamic structure evolution of overlying stratums, and choosing the global search optimizationalgorithm-geneticalgorithm,besides combining the implicit nonlinear relationship between supporting resistance and the multi parameters of the overlying rock to find the minimum between field measured value and numerical calculation values, and the unknown lithologic parameters were determined when the minimum was *** these unknown parameters, including the rock mass density, mechanical parameters—elasticity modulus and poisson ratio, and strength parameters—cohesion and internal friction ***, choosing the No.8206 working face in Qingciyao coal mine as the testing site,the hard stratum fracture overlying which always lead to the rapidly increase of supports resistance, and combining the hydraulic supporting resistance value variation with time, and using the algorithm to acquire the optimal parameters and instability rules of the main roof, and the simulation results show a good agreement with the measured ***, in this study, using the optimal numerical model can well analyze the fracture characteristic of the overlying stratums and the variation of the hydraulic supports with the different advance distances.
Ideal step signal is nonexistent in practical application and the input signals used in system identification are actually not ideal step signals. This introduced errors to the direct identification modeling method th...
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Ideal step signal is nonexistent in practical application and the input signals used in system identification are actually not ideal step signals. This introduced errors to the direct identification modeling method that based on the ideal step input assumption. Therefore, an improved algorithm based on non-ideal step signal input was proposed in this paper. A parameter represent the time of the non-ideal step signal was introduced in this algorithm, and it can be decided automatically during the model identification by using genetic optimization algorithm(GA), which means that this proposed identification modeling algorithm has higher precision and also can be used directly in the practical application. The effectiveness and applicability of this method has been demonstrated through the simulation model identification under the non-ideal step signal input.
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