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针对海上浮式装置力学分析中选用不同截止频率阈值得到重构的冲击载荷对结构响应结果有较大影响的问题,采用变分模态分解(Variable Mode Decomposition, VMD)方法得到冲击载荷各本征模态函数、对应频谱的特征频率和最大加速度幅值。选取不同的截止因数,重构得到不同的冲击载荷。数值仿真结果表明:当截止因数为0.01时,重构的冲击载荷动力学响应与原始冲击载荷动力学响应基本保持一致;在保证足够的安全裕度的前提下,当截止因数选0.20时,可获得更低的截止频率。 相似文献
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Yu Cheng Xinnan Xu Mengfan Wang Chengwei Deng Yi Sun Chenglin Yan Tao Qian 《Advanced functional materials》2023,33(44):2302332
As a promising energy carrier, ammonia synthesis by electrocatalytic nitrogen reduction reaction (eNRR) is a promising green and low-carbon ammonia synthesis strategy that can replace the traditional Haber–Bosch process. However, the development of eNRR processes is mainly severely constrained by competitive hydrogen evolution reaction (HER), and the corresponding strategies to inhibit this adverse side reaction to obtain high eNRR selectivity are still limited. In addition, for this complex reaction involving gas–liquid–solid three-phase interface and proton/electron transfer, it is great significance to analyze and summarize the existing inhibition HER strategies from the viewpoint of dynamics. In view of this, this work reviews proton supply/filtration regulation strategy in catalytic system, allowing a systematic survey of the literature focusing on interface membrane regulation (inorganic membrane and organic membrane), electrolyte regulation (metal-mediated strategy and electrolyte ion regulation strategy) and system device design (electrode structure design and electrolytic cell device design). Constructive catalytic system design guidance is also suggested to inhibit hydrogen evolution and improve NH3 selectivity, aiming for scalable and economically feasible applications. 相似文献
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针对低转速齿轮箱齿轮故障特征频率低、故障特征频率易被背景噪声淹没,使其难以准确提取的问题,提出了基于参数优化的变分模态分解(parameter optimization variational mode decomposition,简称POVMD)和循环自相关函数(cyclic autocorrelation function,简称CAF)结合的故障诊断方法。首先,通过POVMD对原始信号进行分解,选用余弦相似度度量选取敏感的本征模态函数(intrinsic mode function,简称IMF);其次,计算其循环自相关函数谱,获得包含调制特征的循环自相关函数谱切片;最后,使用Teager能量算子(Teager energy operator,简称TEO)算法对切片解调,提取故障特征频率。同时将本方法与相关方法进行了对比分析,特征频率提取效果更加显著,仿真信号和实验数据分析验证了该方法的有效性和可靠性。 相似文献
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金属有机框架(MOF)材料由于其比表面积大、孔隙率高、结构可调控和单分散的活性中心等特性,在吸附分离、气体储存和电催化等领域具有巨大的应用前景,其中,在催化领域的应用尤为突出.目前,利用传统方法所制备的MOF虽然含有具有催化活性的金属,但是MOF中的金属位点通常和有机配体相结合,无法很好的暴露出来,导致在催化过程中表现... 相似文献
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In this article, the effects of coupling agent, silica particle size, and particle shape on the mechanical properties of polyimide (PI) were studied by molecular dynamics (MD) simulations, and the effect of SiO2 surface treated with coupling agent on the mechanical properties of PI was investigated by experiment. At the same doping volume fraction (5%), the simulation results show that the surface interaction energy between the matrix and particle gradually increases with the radius of the embedded nanoparticles. Meanwhile, the interface interaction energy and mechanical properties of the sphere-type were significantly higher than the ones of other shaped nanoparticles. Moreover, the simulations were compared with the experimental results; atomic force microscopy and scanning electron microscopy images can verify that after being treated with coupling agent, interface interaction between nanosilica and PI enhances quite a little. The mechanical experimental results show that the tensile strength and elasticity modulus of pure PI, unbonded (UB) PI/SiO2, and bonded PI/SiO2 films are 34.47 and 1.13, 36.46 and 1.32, and 66.20 MPa and 1.72 GPa, respectively. It is indicated that the coupling agent plays a crucial role in nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48595. 相似文献
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Mengfan Wang Jian Guo Wei Qi Rongxin Su Zhimin He 《Food science and biotechnology》2013,22(3):705-712
In this paper, an effective and green strategy was developed to obtain aglycone isoflavones from soybean through the extraction, hydrolysis, and purification steps. Firstly, a novel ethanol-alkaline extraction method was designed and optimized. The high extraction yield (94.34%) of isoflavones was achieved under the optimal extraction conditions of pH 9.0, 70°C, 60 min, ethanol concentration of 65%, and 1:15 of the solid to liquid ratio. Then, the cellulase (GC-220) was used instead of traditional β-glucosidase to hydrolyze the glycoside isoflavones into aglycone isoflavones which gave an excellent conversion of 95%. Finally, the crude aglycone isoflavones have been purified by an environmental-friendly procedure comprised of ethanol precipitation, ethyl acetate extraction, and water rinse. The final amount of aglycone isoflavones obtained was 1.279 mg for every gram of defatted soybean by this strategy, and the final recovery, and purity of aglycone isoflavones could achieve 80.38 and 87.21%, respectively. 相似文献
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Yuefei Wang Renliang Huang Wei Qi Yanyan Xie Mengfan Wang Rongxin Su Zhimin He 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(24):2893-2902
The wetting and drying of drops on flexible fibers occurs ubiquitously in nature, and the capillary force underlying this phenomenon has motivated our great interest in learning how to direct supramolecular self‐assembly. Here, the hierarchical co‐assembly of two aromatic peptides, diphenylalanine (FF) and ferrocene‐diphenylalanine (Fc‐FF), is reported via sequential, combinatorial assembly. The resulting dandelion‐like microstructures have highly complex architectures, where FF microtube arrays serve as the scapes and the Fc‐FF nanofibers serve as the flower heads. Homogeneous FF microtubes with diameters tailored between 1 and 9 μm and wall thickness ranging from 70 to 950 nm are initially formed by controlling the degree of supersaturation of the FF and the water content. Once the FF microtubes are formed, the growth of the dandelion‐like microstructures is then driven by the capillary force, derived from the wetting and drying of the Fc‐FF solution on the FF microtubes. This simple and ingenious strategy offers many opportunities to develop new and creative methods for controlling the hierarchical self‐assembly of peptides and thus building highly complex nano and microstructures. 相似文献
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Yingying Zhao Mengfan Wu Zhiyong Ji Yuanyuan Wang Jiale Li Jianlu Liu Junsheng Yuan 《Frontiers of Chemical Science and Engineering》2019,13(4):832
The desulfurization by seawater and mineral carbonation have been paid more and more attention. In this study, the feasibility of magnesia and seawater for the integrated disposal of SO2 and CO2 in the simulated flue gas was investigated. The process was conducted by adding MgO in seawater to reinforce the absorption of SO2 and facilitate the mineralization of CO2 by calcium ions. The influences of various factors, including digestion time of magnesia, reaction temperature, and salinity were also investigated. The results show that the reaction temperature can effectively improve the carbonation reaction. After combing SO2 removal process with mineral carbonation, Ca2+ removal rate has a certain degree of decrease. The best carbonation condition is to use 1.5 times artificial seawater (the concentrations of reagents are 1.5 times of seawater) at 80°C and without digestion of magnesia. The desulfurization rate is close to 100% under any condition investigated, indicating that the seawater has a sufficient desulfurization capacity with adding magnesia. This work has demonstrated that a combination of the absorption of SO2 with the absorption and mineralization of CO2 is feasible. 相似文献