混合动力车辆动力系统建模与仿真

以并联式混合动力车辆为研究对象,基于MATLAB／Simulink软件,建立了发动机、电动机、蓄电池以及整车仿真模型,制定了整车控制策略．仿真结果表明,应用该策略对发动机与电机间的功率输出进行协调控制,能明显提高整车燃油经济性,并能够维持SOC在规定的工作区间变化．     

Reversible and irreversible domain wall dynamics in [011]C oriented relaxor ferroelectric single crystals

Domain wall motions mainly affect all kinds of properties of ferroelectric materials, such as piezoelectricity, dielectric response, and mechanical loss, and the extrinsic contributions associated with domain wall motions have always been an important issue. In this study, the reversible and irreversible extrinsic contributions to the dielectric properties of [011]_C-oriented 0.27Pb(In_1/2Nb_1/2)O₃-0.46Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃:Mn single crystals have been extracted by the Rayleigh analysis. We found that in the unpoled samples, the extrinsic contributions of reversible and irreversible domain wall motions to dielectric properties significantly reduced, whereas after poling, only the irreversible extrinsic contribution decreased. The pinning effect in the 2R domain structure is much weaker than that in the 4R domain structure, leading to the low enhancement of Q_m and a slight decrease in piezoelectricity caused by acceptor doping in 2R domain structure. This study explores the domain wall dynamics of acceptor-doped single crystals and mainly guides on further performance optimization in PbTiO₃-based relaxor single crystals.     

Crack growth resistance of natural rubber reinforced with carbon nanotubes

Carbon nanotubes (CNTs)/natural rubber (NR) composites are prepared through ultrasonically assisted latex mixing combined with a two-roll mixing process, and their crack growth behavior is examined to evaluate their fatigue properties. CNTs/NR shows a reinforcement of crack growth resistance compared to unfilled NR. The measurements of the tearing energy and the hysteresis loss show that CNTs/NR exhibits more energy dissipation than NR. Also, strain-induced crystallization (SIC) around the crack tip of CNTs/NR and NR composite was examined at different fatigue strains. CNTs positioned at the crack tip led to a crack branching at low fatigue strain, which is responsible for the improvement of the crack growth resistance of CNTs/NR. However, the inclusion of CNTs renders NR higher crystallinity and larger crystallization zones in front of the crack tip at high fatigue strains, which allows more energy dissipation during crack growth. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48447.     

Free electron laser based on the Smith-Purcell radiation

The electromagnetic radiation is sti mulated when anelectron beampasses a metallic periodic structure like adiffraction grating at a fixed distance close to the sur-face.This phenomenon is known as the Smith-Purcelleffect .The radiation mechanism was pred…     

行星齿轮的固有特性研究

考虑了行星轮系的啮合刚度和扭转刚度等因素,基于拉格朗日方程建立了行星轮系的动力学方程。应用数值方法求解了行星轮系的无阻尼自由振动动力学方程,获得了系统不同工况下的特征值及其对应的振型。分析表明,不同工况下系统的动态特性各不相同,太阳轮、行星架、行星轮和内齿圈转动惯量对系统的动态特性的影响也各不相同。     

基于OPC技术的数据采集系统设计

设计了一种基于C/S模式的OPC客户端,实现了DCS系统与数据库之间基于OPC技术的通讯,并将其应用于水泥生产优化软件数据采集系统。实验证明该方法成功解决了SQL Server、智能控制软件与DCS工控软件的数据交换问题。     

Microstructure and mechanical properties of Mo0.9Cr0.1AlB solid solution

In this study, Mo_0.9Cr_0.1AlB solid solution ceramic bulks were prepared from the element powder mixtures using hot pressing sintering method. Compared with MoAlB ceramics, the grains of as-prepared Mo_0.9Cr_0.1AlB were refined obviously. The lattice constants of Mo_0.9Cr_0.1AlB were confirmed to be a = 3.205 Å, b = 13.999 Å and c = 3.098 Å. The density of Mo_0.9Cr_0.1AlB was lower than that of MoAlB due to the incorporation of Cr element. In addition, the effect of doping Cr element on the comprehensive mechanical properties was studied as well. The hardness and compressive strength were improved significantly. In comparison with MoAlB ceramic, the improvement of mechanical properties could be attributed to solid solution strengthening and grain refinement.     

利用Aspen Plus计算气体物质的溶解度

采用化工流程模拟软件Aspen Plus建立气体物质溶解度的计算模型,并利用灵敏度分析功能研究不同温度和压力下的溶解度数据。以CO2为例,计算其在0.1 MPa不同温度下和20℃时不同压力下的水中溶解度,模拟计算结果与文献数据比较相对偏差较小,吻合良好。研究结果表明:本文建立的气体物质的溶解度计算方法是可行的,可为工业生产提供可靠的数据。     

Cobalt nanoparticle decorated N-doped carbons derived from a cobalt covalent organic framework for oxygen electrochemistry

The low cost and highly efficient construction of electrocatalysts has attracted significant attention owing to the use of clean and sustainable energy technologies. In this work, cobalt nanoparticle decorated N-doped carbons (Co@NC) are synthesized by the pyrolysis of a cobalt covalent organic framework under an inert atmosphere. The Co@NC demonstrates improved electrocatalytic capabilities compared to N-doped carbon without the addition of Co nanoparticles, indicating the important role of cobalt. The well-dispersed active sites (Co–N_x) and the synergistic effect between the carbon matrix and Co nanoparticles greatly enhance the electrocatalytic activity for the oxygen reduction reaction. In addition, the Co content has a significant effect on the catalytic activity. The resulting Co@NC-0.86 exhibits a superb electrocatalytic activity for the oxygen reduction reaction in an alkaline electrolyte in terms of the onset potential (0.90 V), half-wave potential (0.80 V) and the limiting current density (4.84 mA·cm^–2), and a high selectivity, as well as a strong methanol tolerance and superior durability, these results are comparable to those of the Pt/C catalyst. Furthermore, the superior bifunctional activity of Co@NC-0.86 was also confirmed in a home-built Zn-air battery, signifying the possibility for application in electrode materials and in current energy conversion and storage devices.     

Syntheses and Structural Characterization of Co(II) Coordination Polymers Supported by Bis(<Emphasis Type="Italic">N</Emphasis>-benzimidazolyl)methane and Bis(<Emphasis Type="Italic">N</Emphasis>-imidazolyl)methane

[Co₂(L¹)₂(NCS)₄]·4MeOH 1, [Co(L²)₂(H₂O)₂](Sal)₂·4H₂O (Sal = salicylate) 2 were obtained from self-assembly of the cobalt salts with bis(N-benzimidazolyl)methane (L¹), and bis(N-benzimidazolyl)methane (L²), and their structures were characterized by IR and X-ray diffraction analysis. Complex 1 exhibits a two-dimensional grid structure, whereas complex 2 is a coordination polymer having a one-dimensional linear chain structure. The grid in 1 lies parallel to the crystallographic ab plane and exhibits intra-grid M–M separations of 10.508 × 10.508 Å. Hydrogen bonds hold the cationic chains in 2 together leading to a three-dimensional network structure.