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The thermal dynamics of transformer is a critical issue during operation, since it limits the lifespan and the load capacity of transformers. This paper introduces a finite element method (FEM) coupled fluid-thermal to investigate the thermal performance of oil-immersed power transformers. A two-dimensional (2-D) axially symmetric model is established, according to the basic parameters of a 250 kVA/10kV...
The transformer is one of the most important equipment of the power system, the accident that the lightning impact damages the transformer insulation often happens[1]. The main design method of transformer longitudinal insulation structure design is the wave process calculation which is basis on the transformer electromagnetic optimization design[2] [3]. So research the wave process of the transformer...
This paper deals with the multi-objective optimization of a transverse flux machine with claw-pole and flux-concentrating structure (CPTFM), which is especially suitable for low-speed and high-torque applications due to its high pole pair number. Compared with conventional radial flux machine, the main flux path in CPTFM is three dimensional and transverse to the rotation of the rotor. For this reason,...
The optimal technique for low-thrust trajectory optimization is concerned in this paper. In solar ecliptic coordinate, a normalized three-dimensional orbit transfer model was introduced; the optimal direction of thrust was obtained with linear combination of co-state variables while the Hamiltonian and co-state equations were also established. A switching function was introduced according to Pontryagin's...
In view of the landing site positioning of the lunar probe, this paper proposes a positioning reduction method based on VLBI tracking data, and applies VLBI delay-observation data from more than three baselines to complete positioning reduction with the distance between the lunar lander and the center of the earth as a constraint. Simulation results show that the positioning accuracy of landing point...
Through a literature review, we find that the bidding models based on rational theory have revealed little practical values by only taking into account of environmental constraints leaving bounded rationality neglected. This paper studies how bidders' cognitive limitations will affect their decision process in the framework of bounded rationality and we find that the satisficing rule and the aspiration...
In order to build Timely and effective communication in HF blind-spot (20-100KM), Cobwebb folded dipole antenna was designed as well as matching circuitry. In this paper, antenna structure and antenna electric-height are simulated and amended in the use of electromagnetic simulation software FEKO. Antenna radiation patterns in the different electric-height are given. It is clear that the proper electrical...
In this paper, we present a homography-based method for calibrating the central catadioptric vision system. We consider two cases, i.e. orthographic camera with parabolic mirror and perspective camera with hyperbolic mirror. In both cases, the parameters of the mirror and the extrinsic parameters of the camera are estimated simultaneously, assuming that the intrinsic parameters of the camera are known...
Chaotification is an inverse problem of chaos control. This paper addresses the mechanism of chaotification of buck converter with time-delay feedback. The chaotification model is established moreover the article discusses the chaotification ruler of buck converter in a rigorous mathematic sense. The ranges of control parameters are given using nonlinear dynamics stability theory. Computer simulation...
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