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.
Hydrophilic ceramic membranes would be potential candidates for membrane gas absorption if they could be applied to appropriate separation processes. This study highlights a novel concept for the practical implementation of SO2 absorption in hydrophilic ceramic membrane that exhibits outstanding thermal and mechanical stabilities. With this aim, we investigated experimentally the performance of SO2 absorption into aqueous sodium hydroxide (NaOH) solution in a hydrophilic alumina (Al2O3) membrane contactor in terms of SO2 removal efficiency and SO2 mass transfer flux, and compared the performance with that in a hydrophobic one. A series of experiments were performed at various conditions over a NaOH concentration range of 0-1.0 mol·L-1, a liquid flow rate range of 30-180 ml·min-1, a gas flow rate range of 120-1000 ml·min-1, an inlet SO2 concentration range of 400-2000 μl·L-1, and a temperature range of 10-35℃. It was found that the hydrophilic membrane was more competitive when using a NaOH concentration higher than 0.2 mol·L-1. Furthermore, it can be inferred that the hydrophilic α-Al2O3 membrane exhibited exceptional long-term stability under 480 h continuous operation. 相似文献
Railway‐induced vibrations at low frequencies have become an important environmental issue with the rapid development of urban rail transit. In this study, a new vibration attenuation track (VAT) capable of passively mitigating vibrations at low frequencies is developed based on an integrated theoretical and experimental study. The full‐scale VAT is built which incorporates a floating slab track (FST) and the attached dynamic vibration absorbers (DVAs) with key parameters determined by the fixed‐point theory and modal analysis technique. The vibration attenuation performance of the VAT is investigated under train dynamic loads by establishing a three‐dimensional coupled dynamic model of a metro vehicle‐VAT‐subgrade system, and is further elucidated and validated by carrying out full‐scale dynamic tests under different harmonic loadings. Computational and experimental results both show that vibrations of the track are effectively absorbed by the attached DVAs leading to a significant reduction of the subgrade vibrations at the low frequency of 9–16 Hz. 相似文献
The proliferating effects of 3 different simple triglycerides (tristearin, triolein, and trilinolein) on the human umbilical vein smooth muscle cells (HUVSMCs) induced by oxidized‐LDL (ox‐LDL) were investigated in this study. The protein and mRNA gene expressions of proliferating cell nuclear antigen (PCNA), smooth muscle‐α‐actin (SM‐α‐actin), and monocyte chemoattractant protein‐1 (MCP‐1) in HUVSMCs were measured by Western blotting and real‐time quantitative polymerase chain reaction (PCR). It was shown that in tristearin (SSS) treated HUVSMCs, the saturated fatty acid content was increased, and the compositions of polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid were decreased significantly. On the other hand, triolein (OOO) and trilinolein (LLL) significantly increased the levels of some typical PUFA such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. Moreover, LLL and OOO could upregulate the protein and mRNA expressions of PCNA, MCP‐1 as well as downregulate the expression of SM‐α‐actin. The results also showed that, SSS had significant promotion effects on the proliferation of HUVSMCs induced by ox‐LDL. Although both LLL and OOO could inhibit the proliferation of HUVSMCs induced by ox‐LDL, and might have certain inhibition of the atherosclerotic process. 相似文献