圆弧形拱式跨越管道的动力特性分析

本文对圆弧形拱式跨越管道进行模态分析,采用附加质量法和流体单元两种不同的方法来模拟管道内液体,分析流固耦合效应对管道动力特性的影响,并比较了两种方法的异同。同时还分析了矢高、直径、管壁厚、跨度等参数对管道自振频率的影响。本文得到的结果,能为圆弧形拱式跨越管道的设计和计算提供参考。     

自承式管架桥的有限元分析

本文利用大型通用有限元分析软件ANSYS采用参数化建模对自承式管架桥在静力荷载下的变形和内力进行分析,并进一步分析了支座宽度和包裹角度的变化对结构的影响,提出力学性能更为合理的结构设计建议。     

The 3-dimensional dye-sensitized solar cell and module based on all titanium substrates

Here we report a 3-dimensional dye-sensitized solar cell (3D-DSSCs) and module simulating the fractal structure of the pine tree for capturing sunlight. Compared to traditional flat solar cells, this type of solar cell exhibits superiority of absorbing sunlight from all directions. The fabricated 3D-DSSC and module have achieved 3.36% and 3.19% efficiencies, respectively. The results show that the shade has little effect on the performance of 3D-DSSC and module. It is expected that this 3D-DSSC and module have strong potential for practical application due to their 3D light utilization.     

Co-liquefaction of microalgae and synthetic polymer mixture in sub- and supercritical ethanol

Co-liquefaction of microalgae (Spirulina) and synthetic polymer (HDPE, high-density polyethylene) in sub- and supercritical ethanol was investigated in a stainless steel autoclave (1000 mL) at different reaction temperatures (T), Spirulina/HDPE ratio (R₁), (Spirulina + HDPE)/ethanol ratio (R₂) and solvent filling ratio (R₃). Results showed that the addition of Spirulina to HDPE liquefaction could make the conversion conditions of HDPE milder. The yield of bio-oil obtained at 613 K with a 1/10 R₂ and a 2/10 R₃ was increased by 44.81 wt.% when the R₁ was raised from 0/10 to 4/6. Meanwhile, the synergetic effects (SE) between HDPE and Spirulina were increased from 0 to 30.39 wt.%. Further increasing R₁ resulted in a decrease in SE. The yields of bio-oil increased with increasing R₂ firstly and then declined. An opposite trend was observed for the yield of residue. The effect of R₃ to the yields of liquefaction products was similar to that of R₂. The content of C and H in bio-oils reduced with increasing R₁, while the content of O increased. The bio-oil from pure Spirulina liquefaction runs mainly consisted of oxygen-containing compounds, such as carboxylic acids, esters and ketones. But the major components of bio-oil from co-liquefaction of Spirulina and HDPE mixture were similar to those of pure HDPE-derived bio-oil, in which aliphatic hydrocarbons dominated.     

Highly durable and active non-precious air cathode catalyst for zinc air battery

The electrochemical stability of non-precious FeCo-EDA and commercial Pt/C cathode catalysts for zinc air battery have been compared using accelerated degradation test (ADT) in alkaline condition. Outstanding oxygen reduction reaction (ORR) stability of the FeCo-EDA catalyst was observed compared with the commercial Pt/C catalyst. The FeCo-EDA catalyst retained 80% of the initial mass activity for ORR whereas the commercial Pt/C catalyst retained only 32% of the initial mass activity after ADT. Additionally, the FeCo-EDA catalyst exhibited a nearly three times higher mass activity compared to that of the commercial Pt/C catalyst after ADT. Furthermore, single cell test of the FeCo-EDA and Pt/C catalysts was performed where both catalysts exhibited pseudolinear behaviour in the 12-500 mA cm⁻² range. In addition, 67% higher peak power density was observed from the FeCo-EDA catalyst compared with commercial Pt/C. Based on the half cell and single cell tests the non-precious FeCo-EDA catalyst is a very promising ORR electrocatalyst for zinc air battery.     

Highly stable and effective Pt/carbon nitride (CNx) modified SiO2 electrocatalyst for oxygen reduction reaction

We report a durable and active electrocatalyst, Pt/carbon nitride (CN_x) modified silicon dioxide (SiO₂) composite (donated as CN_x/SiO₂), for oxygen reduction reaction (ORR). CN_x/SiO₂ composite is synthesized by calcination of polypyrrole coated SiO₂ (Ppy/SiO₂) at 800 °C. The structure and composition are assessed using Fourier transform infra-red spectroscopy, X-ray diffraction, transmission electron microscope and energy dispersive spectroscopy. Voltammetry is used to study the activities of Pt immobilized on Vulcan XC-72R and CN_x/SiO₂, respectively. The electrochemical data indicate that Pt supported on CN_x/SiO₂ possesses higher electrocatalytic activity and durability for ORR compared with those of Vulcan XC-72R. All these demonstrate that CN_x/SiO₂ is a promising ORR electrocatalyst support for low temperature fuel cells.     

超声波催化糠偶姻缩合的研究

研究了超声波催化条件下温度、时间和超声波强弱对呋喃甲醛缩合生成糠偶姻的反应产率的影响，结果显示，使用强超声在60℃下回流1h是反应的最佳条件。     

威金斯储气柜中T围栏静力与稳定性分析

本文根据工程实例,应用大型通用结构分析软件ANSYS对威金斯储气柜中T围栏进行有限元分析,通过静力与稳定性分析,研究T围栏常用结构形式的位移与应力的分布规律,以及初始缺陷对T围栏稳定性的影响。本文的结论可为类似结构的设计提供参考。     

Efficient production of hydrogen and multi-walled carbon nanotubes from ethanol over Fe/Al2O3 catalysts

Fe/Al₂O₃ catalysts with different Fe loadings (10-90 mol%) were prepared by hydrothermal method. Ethanol decomposition was studied over these Fe/Al₂O₃ catalysts at temperatures between 500 and 800 °C to produce hydrogen and multi-walled carbon nanotubes (MWCNTs) at the same time. The results showed that the catalytic activity and stability of Fe/Al₂O₃ depended strongly on the Fe loading and reaction temperature. The Fe(30 mol%)/Al₂O₃ and Fe(40 mol%)/Al₂O₃ were both the effective catalyst for ethanol decomposition into hydrogen and MWCNTs at 600 °C. Several reaction pathways were proposed to explain ethanol decomposition to produce hydrogen and carbon (including nanotube) at the same time.     

结合纹理复杂度与小波系数特征的渐进式传输算法

针对远程桌面领域的环境需求,提出了一种结合图像纹理复杂度与小波系数特征的渐进式分层算法。首先根据纹理复杂度进行每个图像块的比特分配来提高对目标比特预算的利用率;然后分析图像块内不同子带特征重要性的顺序优化了高频细节分量在渐进式分层算法中的层级结构,并设计了一种根据小波系数特征逐层添加子带传输的渐进式分层算法;最后实现了每个图像块根据分配的比特以及选取的分层方式进行渐进式传输的编解码系统。测试表明所提出的渐进式传输算法在不同图像传输环境中能够重建出质量更佳的图像,并且更加符合人眼的视觉感知特性。该算法对弱网有着更强的适应性,在桌面远程视频图像传输处理领域表现更佳。