scholarly journals Parameter Design for Time‐Domain Optimization of the Fourth‐Order Carrier Loop in a BDS Receiver

2021 ◽  
Vol 30 (3) ◽  
pp. 584-594
Author(s):  
LI Na ◽  
ZHANG Shufang ◽  
ZHANG Jingbo ◽  
HUAI Shuaiheng ◽  
JIANG Yi
Keyword(s):  
Fourth Order ◽  
Time Domain ◽  
Parameter Design ◽  
Domain Optimization

An efficient application of PML in fourth-order precise integration time domain method for the numerical solution of Maxwell's equations

2013 ◽  
Vol 33 (1/2) ◽  
pp. 116-125
Author(s):  
Zhongming Bai ◽  
Xikui Ma ◽  
Xu Zhuansun ◽  
Qi Liu
Keyword(s):  
Finite Difference ◽  
Numerical Solution ◽  
Fourth Order ◽  
Time Domain ◽  
Fdtd Method ◽  
Time Domain Method ◽  
Integration Time ◽  
Precise Integration ◽  
Content Type ◽  
Domain Method

Purpose – The purpose of the paper is to introduce a perfectly matched layer (PML) absorber, based on Berenger's split field PML, to the recently proposed low-dispersion precise integration time domain method using a fourth-order accurate finite difference scheme (PITD(4)). Design/methodology/approach – The validity and effectiveness of the PITD(4) method with the inclusion of the PML is investigated through a two-dimensional (2-D) point source radiating example. Findings – Numerical results indicate that the larger time steps remain unchanged in the procedure of the PITD(4) method with the PML, and meanwhile, the PITD(4) method employing the PML is of the same absorbability as that of the finite-difference time-domain (FDTD) method with the PML. In addition, it is also demonstrated that the later time reflection error of the PITD(4) method employing the PML is much lower than that of the FDTD method with the PML. Originality/value – An efficient application of PML in fourth-order precise integration time domain method for the numerical solution of Maxwell's equations.

Design and multi-objective optimization of magnetorheological damper considering vehicle riding comfort and operation stability

2021 ◽  
pp. 1045389X2110482
Author(s):  
Zhaoxue Deng ◽  
Xinxin Wei ◽  
Xingquan Li ◽  
Shuen Zhao ◽  
Sunke Zhu
Keyword(s):  
Time Domain ◽  
Vehicle Dynamics ◽  
Mr Damper ◽  
Structure Parameters ◽  
Multi Objective Optimization ◽  
Dynamics Model ◽  
Damping Force ◽  
Domain Optimization ◽  
Operation Stability ◽  
The Time Domain

Mostly, magnetorheological (MR) dampers were optimized based on individual performance, without considering the influence of structure parameters change on vehicle performance. Therefore, a multi-objective optimization scheme of MR damper based on vehicle dynamics model was proposed. The finite element method was used to analyze magnetic flux density distribution in tapered damping channel under different structure parameters. Furthermore, the damping force expression of the tapered flow mode MR damper was derived, and the damping force was introduced into the vehicle dynamics model. In order to improve the ride comfort and operation stability of the vehicle, a collaborative optimization platform combining magnetic circuit finite element analysis and vehicle dynamics model was established. Based on this platform, the optimal design variables were determined by comfort and stability sensitivity analysis. The time domain optimization objective and frequency domain optimization objective are proposed simultaneously to overcome the lack of time domain optimization objective. The results show that compared with the time domain optimization and the initial design, the suspension dynamic deflection, tire dynamic load and vehicle body vertical acceleration are decreased after the time-frequency optimization. At the same time, in the frequency domain, the amplitude of vibration acceleration in each working condition is significantly reduced.

scholarly journals Time Domain Room Acoustic Solver with Fourth-Order Explicit FEM Using Modified Time Integration

2020 ◽  
Vol 10 (11) ◽  
pp. 3750 ◽  
Author(s):  
Takumi Yoshida ◽  
Takeshi Okuzono ◽  
Kimihiro Sakagami
Keyword(s):  
Conventional Method ◽  
Fourth Order ◽  
Time Domain ◽  
Time Integration ◽  
Sound Field ◽  
Time Discretization ◽  
Computationally Efficient ◽  
Order Accuracy ◽  
Practical Applications ◽  
Acoustic Methods

This paper presents a proposal of a time domain room acoustic solver using novel fourth-order accurate explicit time domain finite element method (TD-FEM), with demonstration of its applicability for practical room acoustic problems. Although time domain wave acoustic methods have been extremely attractive in recent years as room acoustic design tools, a computationally efficient solver is demanded to reduce their overly large computational costs for practical applications. Earlier, the authors proposed an efficient room acoustic solver using explicit TD-FEM having fourth-order accuracy in both space and time using low-order discretization techniques. Nevertheless, this conventional method only achieves fourth-order accuracy in time when using only square or cubic elements. That achievement markedly impairs the benefits of FEM with geometrical flexibility. As described herein, that difficulty is solved by construction of a specially designed time-integration method for time discretization. The proposed method can use irregularly shaped elements while maintaining fourth-order accuracy in time without additional computational complexity compared to the conventional method. The dispersion and dissipation characteristics of the proposed method are examined respectively both theoretically and numerically. Moreover, the practicality of the method for solving room acoustic problems at kilohertz frequencies is presented via two numerical examples of acoustic simulations in a rectangular sound field including complex sound diffusers and in a complexly shaped concert hall.

Time domain optimization of wire antennas loaded with passive linear elements using GA

2003 ◽  
Vol 27 (4) ◽  
pp. 345-349 ◽  
Author(s):  
M Fernández Pantoja ◽  
A Rubio Bretones ◽  
A Monorchio ◽  
R Gómez Martı́n
Keyword(s):  
Time Domain ◽  
Domain Optimization ◽  
Linear Elements ◽  
Wire Antennas
Sign in / Sign up

Export Citation Format

Share Document