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Meng Z.,Dalian University of Technology | Hao P.,Dalian University of Technology | Li G.,Dalian University of Technology | Wang B.,Dalian University of Technology | Zhang K.,Beijing Institute of Aerospace Control Devices
Thin-Walled Structures | Year: 2015

Abstract Stiffened shells are affected by numerous uncertainty factors, such as the variations of manufacturing tolerance, material properties and environment aspects, etc. Due to the expensive experimental cost of stiffened shell, only a limited quantity of statistics about its uncertainty factors are available. In this case, an unjustified assumption of probabilistic model may result in misleading outcomes of reliability-based design optimization (RBDO), and the non-probabilistic convex method is a promising alternative. In this study, a hybrid non-probabilistic convex method based on single-ellipsoid convex model is proposed to minimize the weight of stiffened shells with uncertain-but-bounded variations, where the adaptive chaos control (ACC) method is applied to ensure the robustness of search process of single-ellipsoid convex model, and the particle swarm optimization (PSO) algorithm together with smeared stiffener model are utilized to guarantee the global optimum design. A 3 m-diameter benchmark example illustrates the advantage of the proposed method over RBDO and deterministic optimum methods for stiffened shell with uncertain-but-bounded variations. © 2015 Elsevier Ltd. Source


Yang T.,Beijing Institute of Aerospace Control Devices | Zhou L.-B.,Huazhong University of Science and Technology
Dianji yu Kongzhi Xuebao/Electric Machines and Control | Year: 2014

To investigate the influence of the longitudinal dynamic end effect(LDEE) on the magnetic field and performance of the long primary double-sided linear induction motor(LP-DSLIM), the airgap magnetic field for LP-DSLIM was analyzed, in part 1, by using the analytical method. According to the derived analytical expressions of the airgap magnetic flux density, the analytical calculations, when taking into account LDEE, were extended to the prediction of the motor performances, which include electromagnetic thrust, active and reactive power, power factor and efficiency, etc in this part. The analytical results were compared and validated by the predictions from two-dimensioanl finite element analysis. The fact that thrust due to the entry-end effect comes into being as the braking force at high speed, and its influence on the resultant thrust-speed characteristics were investigated by the phasor diagram of the airgap magnetic flux density. The effects of the motor design parameters, including the goodness factor and the pole numbers, on the improving the high speed thrust-speed characteristics for LP-DSLIM were also analyzed. The analysis result show that LDEE makes the rated operating speed in the thrust-speed characteristics be far away from the synchronous speed, thereby resulting in the higher secondary copper losses and lower efficiency. Adjusting the goodness factor has little influence on the thrust improvement, while increasing the pole numbers could effectively alleviate LDEE. Source


Yang T.,Beijing Institute of Aerospace Control Devices | Zhou L.-B.,Huazhong University of Science and Technology
Dianji yu Kongzhi Xuebao/Electric Machines and Control | Year: 2014

To investigate the influence of the longitudinal dynamic end effect (LDEE) on the magnetic field and performance of the long primary double-sided linear induction motor (LP-DSLIM), the one-dimensional time-harmonic magnetic field equations in the airgap region of LP-DSLIM, accounting for LDEE, were developed and solved. The analytical solutions of the fundamental airgap fields and the component fields due to entry-and exit-end are derived. The characteristics of the amplitude, phase and waveform of each three components of the traveling wave, as well as the LDEE wave's influence on the airgap magnetic field distribution were both analyzed. The analytical results were compared and validated by the predictions from corresponding two-dimensional finite element analyses. The variations of LDEE-related characteristic parameters, such as attenuating constant, half-wave length and wave velocity, with the goodness factor were given. The analysis results show that LP-DSLIM and its short primary counterpart exhibit are quite different on the airgap magnetic field distribution, especially operating at high-speed conditions. By adjusting the motor design parameters, the measures to reduce the goodness factor may effectively alleviate LDEE, whilst these effects also degrade the LP-DSLIM fundamental performance. Therefore, the compromised measures should be taken during the design procedures for LP-DSLIM. Source


Yang W.,University of Science and Technology Beijing | Zhu R.,Tsinghua University | Ma B.,Beijing Institute of Aerospace Control Devices
IEEE Transactions on Plasma Science | Year: 2016

There has been considerable interest in nonthermal atmospheric pressure discharges due to their widely used industrial applications. A repetitively pulsed (RP) discharge ignited in microchannels between two nonequally broad planar electrodes is studied in this paper. The discharge current attains several 10-5 A orders of magnitude, and the ion concentration produced in interelectrode space by RP discharge is estimated to be about 1017/m3. The duration of each time of RP discharge is several 10-8 s and the repetition frequency exceeds a few tenths of kilohertz. The repetition frequency of RP discharge depends on the RC product, applied voltage, and the environmental humidity. The experiments of charging aerosol particles by RP discharges have shown that for particles with diameters of 34.8 and 103 nm, the charging efficiency can attain 14.8% and 35%, respectively. © 2015 IEEE. Source


Han B.,Beihang University | Xu Q.,Beihang University | Yuan Q.,Beijing Institute of Aerospace Control Devices
IEEE Transactions on Industrial Electronics | Year: 2016

The combined radial-axial magnetic bearing (CRAMB) with permanent magnet (PM) providing bias magnetic flux is designed for magnetically suspended high-speed electromotor in the compressor for its compact construction. In this paper, the design principle and the initial model of CRAMB are introduced. To improve the performances of CRAMB and better meet the engineering requirements, the optimization is conducted on the bearing. Considering the incompatible objectives of the optimization model, the method of multiobjective optimization (MOO) on the bearing is proposed, which can balance these objectives compared with single-objective optimization (SOO). The objectives and constraints are provided in the form of analytical expressions by means of equivalent magnetic circuit whose rationality is demonstrated by finite-element method (FEM). To optimize the bearing efficiently, the integrated optimum methodology is adopted. After MOO process, the synthetical performances are improved, which are verified by FEM and experiment. © 1982-2012 IEEE. Source

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