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91.
Vehicle active steering control research based on two-DOF robust internal model control 总被引:1,自引:0,他引:1
Because of vehicle’s external disturbances and model uncertainties, robust control algorithms have obtained popularity in vehicle stability control. The robust control usually gives up performance in order to guarantee the robustness of the control algorithm, therefore an improved robust internal model control(IMC) algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness. The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties. In order to separate the design process of model tracking from the robustness design process, the improved 2 degree of freedom(DOF) robust internal model controller structure is given from the standard Youla parameterization. Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm, on the basis of a nonlinear vehicle simulation model with a magic tyre model. Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance, which can enhance the vehicle stability and handling, regardless of variations of the vehicle model parameters and the external crosswind interferences. Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained. 相似文献
92.
《Ceramics International》2016,42(9):10758-10763
Large size Ba4.2Nd9.2Ti18O54 (BNT) ceramics doped with MnCO3, CuO and CoO were prepared by the conventional solid-state method. Only a single BaNd2Ti4O12 phase was formed in all samples. No second phase was found in the XRD patterns. The bulk density increases slightly because of the dopants. The SEM results showed that the grain size of Mn2+and Cu2+-doped BNT ceramics became larger with the increasing amount of dopants. The permittivity of all samples stays the same. However, the Q×f value of BNT ceramics increases by doping, especially with Mn2+ ions. The conductivity of BNT ceramic doped with Mn2+(0.5 mol‰) under high temperature is lower than that without doping. There are fewer defects in Mn2+-doped BNT ceramics. The XPS results indicated that Ti reduction was suppressed in BNT ceramics doped with 0.5 mol‰ Mn2+. BNT ceramics doped with 0.5 mol‰ Mn2+ ions sintered at 1320 °C for 2 h exhibited good microwave dielectric properties, with εr=88.67, Q×f=7408 GHz and τf = 82.98 ppm/°C. 相似文献
93.
《Ceramics International》2016,42(4):5391-5396
Lead-free piezoelectric ceramics, (1−x)SrBi2Nb2O9−xBiFeO3 [(1−x)SBN−xBFO] (x=0.0, 0.03, 0.05, 0.07, 0.10) were prepared by a conventional solid-state reaction method. The crystal structure, microstructure and electrical properties were systematically investigated. All compositions formed layered perovskite structure without any detectable secondary phases. Plate-like morphology of the grains which is characteristic for layer-structure Aurivillius compounds was clearly observed. The excellent electrical properties (e.g., d33~19 pC/N, 2Pr~18.8 μC/cm2) and a high Curie temperature (e.g., Tc~449 °C) were simultaneously obtained in the ceramics with x=0.05. Additionally, thermal annealing studies indicated that the BFO modified SBN ceramics system possessed stable piezoelectric properties, demonstrating that the modified SBN-based ceramics are the promising candidates for high-temperature applications. 相似文献
94.
《Journal of the European Ceramic Society》2022,42(13):5691-5697
Herein, the improvement of the microwave dielectric properties and sintering characteristics of Zn1?xBixVxW1?xO4(x = 0–0.15)-based ceramics is reported. The results showed that an appropriate amount of doping could not only reduce the optimum sintering temperature from 1100° to 900°C, but also enhance the densification of the microstructures and increase the Q×f value from 5351 to 42525 GHz. Additionally, various structural parameters including the phase composition, crystal structure, vibrational and chemical bond characteristics that are correlated with the dielectric properties were systematically investigated. By considering the chemical bond characteristics, the first-principles calculations and the acquired Raman spectra, the interaction between W-O is stronger than Zn-O in the ZnWO4 structure, while the interaction between V-O is stronger than Bi-O in BiVO4. Interestingly, when the Zn0.97Bi0.03V0.03W0.97O4-based ceramics were sintered at 900 °C, improved microwave dielectric properties were acquired (εr =18.32, Q×f=42525 GHz, τf=?67.51 ppm/°C), which provides a promising candidate in low-temperature co-fired ceramics technology. 相似文献
95.
《Journal of the European Ceramic Society》2022,42(13):5643-5651
BiFeO3 thin films, specifically those fabricated by chemical solution deposition, suffer from severe leakage that hinder the acquirements of their intrinsic high polarizations and are thus normally not considered for use in practical electronics. The controlled fabrication of thin films with reduced leakage is of vital importance. In the present work, BiFeO3 films (with thicknesses below ~300 nm), assisted by an interfacial amorphous layer, were fabricated by chemical solution deposition on Pt/Ti/SiO2/Si substrates. This facile method facilitates the growth of the mentioned amorphous layer, and the ferroelectric properties of the obtained films were greatly enhanced. The conducting mechanisms of both types of thin films were systematically investigated to understand the impact of the designed interface. The results not only advance the potential use of BiFeO3 thin films in electromechanical devices but also promote chemical solution deposition as a promising methodology for the fabrication of high-quality ferroelectric films with compressed leakage. 相似文献
96.
97.
《Ceramics International》2014,40(6):7947-7951
Lead free (1−x)(0.8Bi0.5Na0.5Ti0.5O3–0.2Bi0.5K0.5TiO3)–xBiZn0.5Ti0.5O3 (x=0–0.06) (BNT–BKT–BZT) thin films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by a sol–gel processing technique. The effects of BZT content on the structural, dielectric, ferroelectric and piezoelectric properties of the BNT–BKT–BZT thin films were investigated systematically. The BNT–BKT–BZT thin films undergo a transition from ferroelectric to relaxor phase with increasing temperature. The phase transition temperature decreases with the increase of BZT content. The BNT–BKT–BZT thin film with x=0.04 exhibits the best ferroelectric properties (Pmax=40 µC/cm2 and Pr=10 µC/cm2), largest dielectric constant (ε=560) and piezoelectric constant (d33=40 pm/V). This finding demonstrates that the BNT–BKT–BZT thin film has an excellent potential for demanding high piezoelectric properties in lead free films. 相似文献
98.
Anodizing of etched aluminum foil coated with modified hydrous oxide film for aluminum electrolytic capacitor 总被引:1,自引:0,他引:1
Chaolei Ban Yedong He Xin Shao Liping Wang 《Journal of Materials Science: Materials in Electronics》2014,25(1):128-133
Prior to galvanostatical anodization in boric acid solution, aluminum capacitor foil with a tunnel etch structure is treated in a two-step process in which a non-dense hydrous oxide film is first formed on foil in neutral boiling water for 10 min [namely, conventional hydration (CH)] and the hydrous oxide is then modified in a 80 °C weakly acidic solution containing trace amount of citric acid for 3 min [namely, modified conventional hydration (MCH)]. After modification, the hydrous oxide film becomes dense and thin. Time variations in the anode potential during anodizing were monitored, and the structure and dielectric properties of the anodic oxide films were examined by transmission electron microscopy, X-ray diffraction and electrochemical impedance spectroscopy measurements. It was found that the MCH-induced hydrous oxide film results in a decreased power consumption during anodization and an increased crystallized anodic oxide film, which has a high specific capacitance and a low specific resistance, comparing with the CH-induced hydrous oxide film. 相似文献
99.
Three novel complexes [Cu4(ccsa)4(Py)8] (1), [Mn3(ccsa)4(Py)6(H2O)2]·2Py·H2O (2) and [MnFe2(ccsa)4(Py)6(H2O)2] (3) (H2ccsa = 3-carboxy-5-chloro-salicylald-ehyde) have been synthesized and characterized by elemental analysis, power X-ray diffraction (PXRD), Infrared (IR) spectrum and X-ray single-crystal diffraction. Complex 1 shows a rare 16-MC-4 macrocycle framework with [Cu-O-C-O] repeating unit, and four Cu ions connected by the carboxy groups from four ligands. Complexes 2 and 3 are isostructural and the metal ions exhibit reverse “U” shape arrangement. Magnetic studies reveal unexpected ferromagnetic coupling and field-dependent slow magnetic relaxation in complex 1. 相似文献
100.
The method of moments (MoM) solution on the magnetic field integral equation (MFIE) for electromagnetic scattering problems of conducting objects with Rao–Wilton–Glisson (RWG) basis functions requires the evaluation of almost singular double surface integrals over triangular subdomains. Calculating these integrals accurately is essential for the successful solution of the MFIE by MoM especially for small sharp-edged conducting objects. This paper studies the singularity of the MFIE and uses an accurate singularity extraction technique to avoid logarithmic singularity of the integration on the testing triangles for the MFIE. Based on the numerical examples of several small sharp-edged conducting objects, it is demonstrated that the accuracy of the MFIE is improved greatly with the use of the new singularity extraction technique. 相似文献