The traction motor is the power source of the locomotive. If the surface waviness occurs on the races of the motor bearing, it will cause abnormal vibration and noise, accelerate fatigue and wear, and seriously affect the stability and safety of the traction power transmission. In this paper, an excitation model coupling the time-varying displacement and contact stiffness excitations is adopted to investigate the effect of the surface waviness of the motor bearing on the traction motor under the excitation from the locomotive-track coupled system. The detailed mechanical power transmission path and the internal/external excitations (e.g., wheel–rail interaction, gear mesh, and internal interactions of the rolling bearing) of the locomotive are comprehensively considered to provide accurate dynamic loads for the traction motor. Effects of the wavenumber and amplitude of the surface waviness on the traction motor and its neighbor components of the locomotive are investigated. The results indicate that controlling the amplitude of the waviness and avoiding the wavenumber being an integer multiple of the number of the rollers are helpful for reducing the abnormal vibration and noise of the traction motor.
Power conversion efficiency (PCE) and stability are two important properties of perovskite solar cells (PSCs). Particularly, defects in the perovskite films could cause the generation of trap states, thereby increasing the nonradiative recombination. To address this issue, suitable dopants can be incorporated to react with non-bonded atoms or surface dangling bonds to passivate the defects. Herein, we introduced TiI4 into CH3NH3PbI3 (MAPbI3) film and obtained a dense and uniform morphology with large crystal grains and low defect density. The champion cell based on 0.5% TiI4-doped MAPbI3 achieved a PCE as high as 20.55%, which is superior to those based on pristine MAPbI3 (17.64%). Moreover, the optimal solar cell showed remarkable stability without encapsulation. It retained 88.03% of its initial PCE after 300 h of storage in ambient. This work demonstrates TiI4 as a new and effective passivator for MAPbI3 film. 相似文献
Journal of Porous Materials - Based on a new semi-rigid tridentate azole ligand, a porous metal–organic framework (MOF), {[Ni3(tmpa)2(bdc)3]·6DMF}n (1)... 相似文献
A series of rare earth zirconates (RE2Zr2O7) high-entropy ceramics with single- and dual-phase structure were prepared. Compared with La2Zr2O7 and Yb2Zr2O7, the smaller “rattling” ions (Yb3+, Er3+, Y3+) have been incorporated into pyrochlore lattice in (La0.2Nd0.2Y0.2Er0.2Yb0.2)2Zr2O7 (LNYEY) while larger ions (La3+, Nd3+, Sm3+, Eu3+) incorporated into fluorite lattice in (La0.2Nd0.2Sm0.2Gd0.2Yb0.2)2Zr2O7 (LNSGY). Due to high-entropy lattice distortion and resonant scattering derived from smaller ions Yb3+, Er3+, and Y3+, LNYEY shows a lower glass-like thermal conductivity (1.62-1.59 W m-1 K-1, 100-600℃) than LNSGY (1.74-1.75 W m-1 K-1, 100-600℃). Moreover, LNYEY and LNSGY exhibit enhanced Vickers’ hardness (LNYEY, Hv = 11.47 ± 0.41 GPa; LNSGY, Hv = 10.96 ± 0.26 GPa) and thermal expansion coefficients (LNYEY, 10.45 × 10-6 K-1, 1000℃; LNSGY, 11.02 × 10-6 K-1, 1000℃). These results indicate that dual-phase rare-earth-zirconate high-entropy ceramics could be desirable for thermal barrier coatings. 相似文献
Face aging (FA) for young faces refers to rendering the aging faces at target age for an individual, generally under 20s, which is an important topic of facial age analysis. Unlike traditional FA for adults, it is challenging to age children with one deep learning-based FA network, since there are deformations of facial shapes and variations of textural details. To alleviate the deficiency, a unified FA framework for young faces is proposed, which consists of two decoupled networks to apply aging image translation. It explicitly models transformations of geometry and appearance using two components: GD-GAN, which simulates the Geometric Deformation using Generative Adversarial Network; TV-GAN, which simulates the Textural Variations guided by the age-related saliency map. Extensive experiments demonstrate that our method has advantages over the state-of-the-art methods in terms of synthesizing visually plausible images for young faces, as well as preserving the personalized features. 相似文献
With co-substitution of (Li0.5Sm0.5) at A site and W at B site, the electrical properties of modified Ca0.92(Li0.5Sm0.5)0.08Bi2Nb2-xWxO9 [(CLS)BN-xW, x = 0, 0.015 and 0.03] piezoceramics with ultrahigh Curie temperature (TC) of > 930 °C were enhanced dramatically. The increased resistivity induced by the co-substitution ensure them to be polarized under an enough high field. Combined with the increase of spontaneous ferroelectric polarization (PS), the significant enhancements in the piezoelectric, dielectric and ferroelectric properties can be obtained in the composition x = 0.015. Furthermore, the piezoelectric activity (d33) and bulk resistivity (ρb) of (CLS)BN-0.015 W can be further enhanced at an appropriate sintering temperature. This optimum composition sintered at 1170 °C shows ultrahigh TC of ~948 °C, d33 of ~17.3 pC/N and ρb of ~6.9 MΩ cm at 600 °C, which are comparable to those of the reported high-temperature Aurivillius piezoceramics with TC > 850 °C. 相似文献
Sr0.9La0.1TiO3 based textured ceramics (SLTT-S3T) with a texture fraction of 0.81 are successfully fabricated by the reactive template grain growth method, in which Sr0.9La0.1TiO3/20 wt%Ti was used as matrix and 10 wt% plate-like Sr3Ti2O7 template seeds were used as templates. The phase transition, microstructure evolution, and the anisotropic thermoelectric properties of SLTT-S3T ceramics were investigated. The results show that the ceramics are mainly composed of Sr0.9La0.1TiO3 and rutile TiO2 phases. Grains grow with a preferred orientation along (h00). A maximum ZT of 0.26 at 1073 K was achieved in the direction perpendicular to the tape casting direction. The low lattice thermal conductivity of 1.9 W/(m K) at 1073 K was obtained decreased by 34%, 40%, and 38% compared with non-textured, SrTiO3 and Sr0.9La0.1TiO3 ceramics prepared by the same process, can be attributed to the enhanced phonon scattering by the complex multi-scale boundaries and interfaces. This work provides a strategy of microstructural design for thermoelectric oxides to decrease intrinsic lattice thermal conductivity and further regulate thermoelectric properties via texture engineering. 相似文献
Directional lamellar porous titanium scaffolds are widely used as bone implant bearing materials because of their anisotropic pore structure. Their mechanical properties can be effectively improved by enhancing the strength of pore walls through the introduction of ceramics. In this work, porous titanium implants were prepared by freeze casting combined with TiH2 decomposition. The graphene was introduced into the pore walls of porous titanium, which could transform into titanium carbide (TiC) in situ upon sintering. TiC was evenly distributed in the lamellar pore walls, and the interface was well bonded. The compression strength of the fabricated implants was up to 389.94 MPa when the graphene content was 3 wt%, which was 377.8% times as high as the porous titanium. The crack propagation was resisted by TiC because of the “pinning” effect on the pore wall. Some of TiC were pulled out from the matrix, and others were fractured. The strength of the fabricated implants was improved significantly by the large consumption of fracture energy. Also, fabricated porous titanium implants with TiC are suitable for bone implantation. 相似文献
For solid oxide fuel cells, an important structural requirement is that the electrolyte layer needs to be dense and the electrode layer porous, which is difficult to obtain by conventional cosintering. In this work, flash cosintering of a double layer structure consisting of a Gd-doped ceria substrate with a lanthanum strontium cobalt ferrite nanofibre coating is investigated. Experimental and finite element modelling results reveal that when the LSCF layer is connected to the electrode, the heat is concentrated in the LSCF layer, which leads to a huge temperature gradient and introduces severe cracking. When the LSCF layer is electrically isolated from the electrode, the heat is concentrated in the GDC layer, and the temperature gradient is dramatically reduced. In this situation, the density of GDC can reach 92.86% while a high porosity of 52.26% is maintained in the LSCF layer, which is higher than that of the conventional cosintered sample. 相似文献