大循环粉煤常压气化技术在玻璃熔窑上的应用探讨

简介了大循环粉煤常压气化技术的原理和优势,针对玻璃熔窑的炉型结构与工艺要求,通过理论计算和软件模拟,探讨了大循环粉煤常压气化技术在玻璃熔窑上应用的可行性和前景。     

Dynamic,conformational and topological properties of ring–linear poly(ethylene oxide) blends from molecular dynamics simulations

We present results for the equilibrium conformational and dynamic properties of ring–linear poly(ethylene oxide) (PEO) blends from detailed molecular dynamics (MD) simulations with a thoroughly validated and very accurate forcefield. The simulations have been performed in the isothermal–isobaric (NPT) statistical ensemble with blends where the two types of chains (ring and linear) have the same size. Simulations with two different chain lengths, corresponding to molecular weights equal to 1800 and 5000 g/mol, allowed us to study the dependence of these properties on molecular length. Overall, the presence of linear chains seems to considerably slow down the orientational relaxation of ring molecules and to lower their diffusivity, to a degree that depends strongly on chain length and level of contamination of the melt by linear chains. The longer the size of the molecules the more pronounced the decrease in ring diffusivity is, at a given mass fraction of linear chains. To explain the reduction in the relaxation and mobility of ring molecules when they mix with linear chains to form a blend, selected configurations from the MD simulations were subjected to a detailed topological analysis which revealed significant threading of the cyclic molecules by the linear ones. Our simulation data indicate that, due to threading, ring dynamics in ring–linear PEO melts is strongly heterogeneous. An analysis of the statistics of the lifetimes of ring–linear topological constraints (TCs) reveals a long tail on the long time scale, demonstrating that many of these TCs are long-lived. By inspecting individual ring–linear PEO pairs we found that, in many cases, the lifetimes of these TCs are up to one order of magnitude larger than the typical time characterizing ring relaxation in the pure ring melt. This phenomenon was more pronounced in the blend with the longer molecules (molecular weight = 5000 g/mol).     

上海市内环高架道路存在问题及对策措施

通过对上海市内环高架道路的交通分析 ,提出其四大特征、通车后存在问题及解决问题的对策措施     

Study on contact stresses of un‐stepped rounded D‐ring under uniform squeeze rate and internal pressure by photoelastic experimental hybrid method

The stresses that occur in an un‐stepped rounded D‐ring loaded with various internal pressures and compressed to a 20% squeeze rate are analyzed using photoelastic experimental hybrid method. The analysis shows that the contact stresses on both the upper and front sides of the D‐ring increase as the applied internal pressure increases with the magnitudes of σ_X and σ_Y being considerably higher than those of τ_XY. At a pressure of zero and 20% compression, the isochromatic fringe patterns of the un‐stepped D‐ring are almost symmetrical. However, as the internal pressure applied to the D‐ring increases the isochromatic fringe patterns shift and curve smoothly towards the extrusion gap making the upper and front sides to be more stressed than the lower side. At a pressure of 1.96 MPa and above, the contact stresses on the upper side were found to be almost constant along the contact length. By supplying a fillet radius of 2.1 mm at the corners of the un‐stepped D‐ring the high stresses at the corners were reduced by up to 45%. The results from the study further demonstrated that the un‐stepped rounded D‐ring with a ratio of r/d = 0.3 to be can be an alternative choice to the O‐ring for sealing applications. Interestingly, the pressures that the un‐stepped D‐ring can withstand before extrusion are higher than those of an O‐ring.     

Optical Properties of Ca_(0.25)Ba_(0.75)Nb_2O_6 Thin Films Prepared by Spinning Coating

Ca0.25Ba0.75Nb2O6 (CBN25) thin film was prepared on quartz substrate by spinning coating and the optical properties were investigated by a Hitachi U-3410 spectrophotometer and a Metricon 2010 prism coupler. The optical band gap, thickness and refractive index at 632.8 nm of the CBN25 thin film were determined to be 3.65 eV, 529 nm and 2.2258, respectively. The dispersion of the refractive index fitted to Sellmeier relation well and optical waves could be guided into the thin film, which implied that CBN25 thin films were promising for integrated optics and optically active devices.     

回转支承圈体变形规律研究

通过对一种回转支承加工过程的跟踪测量,对数据进行了采集与处理,绘制了各工序中回转支承圈体的收缩量和圆度变化曲线.通过该曲线总结出回转支承圈体在制造过程中的变形规律.结果表明,热处理工序对回转支承圈体的变形影响最大.     

Surface roughness and material strength of tribo-pairs in ring compression tests

The quantification of friction by means of simple models such as Amonton-Coulomb’s and the law of constant friction is questionable because the influence of surface roughness and material strength, among other factors, is not considered.This paper provides a comprehensive analysis on the influence of surface roughness and material strength in friction and proposes a new operator based on a sigmoid function to incorporate the combined influence of both phenomena in a modified version of the Amonton-Coulomb’s law.The presentation is supported by thoroughly researched quantitative data obtained from experimentation and finite element modelling of the ring compression test.     

转杯式纺纱生产线自动控制系统的设计

随着纺纱厂生产规模的扩大,使得传统人工纺纱逐渐淡出纺纱行业。本文介绍了转杯纺纱生产线电气自动控制系统的设计过程,详细介绍了系统的硬件和软件组成,系统的投入使用提高了纺织厂的生产效益和产量规模,具有一定的推广价值。     

浅析橡胶密封圈的压缩率对密封性能的影响

通过两个实例分析，指出了橡胶密封圈的压缩率偏低是引起液压系统产生泄漏的一个重要原因。提出了解决压缩率偏低的方法。     

旋转喷头法对铝液的高效除氢作用

从铝液内部的净化剂气泡除氢和铝液表面吸氢两个角度阐述了旋转喷头吹气法能实现铝液 高效除氢净化的基本观点。