A revised additivity rule for electron scattering from ethylene, propene, butene, ethane, propane and butane

Considering the difference between the bound atom in a molecule and the free atom, the original additivity rule is revised. Using the revised additivity rule, the total cross sections for electron scattering by ethylene (C₂H₄), propene (C₃H₆), butene (C₄H₈), ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀) are calculated over the energy range 10-1000 eV. The results of the revised additivity rule are compared with those obtained by experiments and the revised additivity rule can give better agreement with experimental values than the original additivity rule.     

The effect of triethylamine on the hydrodechlorination of chlorophenols on Pd/C at low temperature

The hydrodechlorination (HDC) of chlorophenols on 5 wt.% Pd/C catalyst was investigated at low temperature under ordinary pressure by using triethylamine (Et₃N) as a base additive. The inhibition effect of Et₃N on the HDC existed obviously and can be efficiently reduced by stepwise addition of Et₃N. For the first time, the high activity of Pd/C for HDC of chlorophenols was observed at 258 K.     

张拉成形曲面的应力松弛分析

对膜结构施工中由裁剪片拼接张拉形成的膜面进行应力松弛分析,考察膜面应力随时间逐渐减小的变化规律。考虑膜材材料和几何双重非线性,采用广义Maxwell黏弹性模型建立积分型本构方程,推导增量本构方程,编制非线性有限元程序实现成形曲面的应力松弛数值分析过程。对聚氯乙烯 (PVC)膜材进行了不同初始应力水平下的单轴应力松弛试验和不同应力比下的双轴应力松弛试验,用5单元的广义Maxwell黏弹性模型对试验数据拟合,确定了膜材本构方程的黏弹性参数。进行十字形膜片的加载及应力松弛试验,对其试验过程进行数值分析,结果表明试验结果与数值分析结果基本一致,验证了成形曲面黏弹性数值分析方法的可行性。对PVC膜材马鞍形曲面算例进行黏弹性分析,结果表明,马鞍形曲面在张拉完成4 d后,膜面平均应力降低了44%。     

Adsorption properties of novel chelating resins containing 2‐amino‐5‐methylthio‐1,3,4‐thiadizole and hydrophilic spacer arms for Hg2+ and Ag+

The adsorption properties, including the adsorption kinetics, adsorption isotherms, and adsorption selectivity, of newly formed chelating resins that contained a heterocyclic functional group and a hydrophilic spacer arm of poly(ethylene glycol) [polystyrene–diethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–DEG–AMTZ) and polystyrene–triethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–TEG–AMTZ)] were studied in detail. The results show that the adsorption kinetics of PS–DEG–AMTZ and PS–TEG–AMTZ for Hg²⁺ and Ag⁺ could be described by a pseudo‐second‐order rate equation. The introduction of a spacer arm between the polymeric matrix and functional group was beneficial for increasing the adsorption rates. The apparent activation energies of the resins for Hg²⁺ and Ag⁺ were within 20.89–32.32 kJ/mol. The Langmuir model could describe the isothermal process of Hg²⁺ and Ag⁺. The competitive adsorption of the resins for Hg²⁺ and Ag⁺ in binary mixture systems was also investigated. The results show that Hg²⁺ and Ag⁺ were adsorbed before the other metal ions, such as Cu²⁺, Zn²⁺, Fe³⁺, Cd²⁺, and Pb²⁺, under competitive conditions. Five adsorption–desorption cycles were conducted for the reuse of the resins. The results indicate that these two resins were suitable for reuse without considerable changes in the adsorption capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Experimental evidence of structural evolution for TiB2 microcrystal under externally high stresses

The morphology evolution and defect structure of TiB₂ microcrystals treated under high stresses were analyzed using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results show that hexagonal TiB₂ with large particle size gradually evolved to flowerlike TiB₂ with small particle size under high stresses. The evolution process is mainly determined by the preferential cleavage of TiB₂ microcrystal, and the presence of multiple lamellar nanotwin and edge dislocation directly provides some evidence of plastic deformation and structural evolution. For clarity, a possible model is suggested based on the HTREM observation and the natural properties of TiB₂ materials to explain the process mechanism.     

远程视频监控系统中DS/FH混合扩频技术研究

远程视频监控系统中提高系统的可靠性和稳定性很重要。针对这一问题提出在系统中采用DS/FH混合扩频技术。详细讨论了采用DS/FH混合扩频通信技术系统的抗宽带阻塞干扰、多径干扰性能,并通过SYSTEMVIEW仿真软件进行仿真分析,分析和仿真结果表明了采用此技术的可行性。给出了该通信模式下的系统模型,为实际系统的设计与实现奠定了基础。     

各向异性软黏土地基上浅基础破坏包络面研究

 根据已有的关于土体强度各向异性的表达式,针对基于Tresca屈服准则的理想弹塑性模型进行改进,使之可以考虑不排水条件下软黏土强度的各向异性,并在大型通用有限元软件ABAQUS中予以数值实施。联合应用swipe加载模式和固定位移比加载模式,对于条形浅埋基础在竖向荷载V、水平荷载H与力矩荷载M的复合加载条件下的承载性能进行比较系统的数值模拟,主要探讨地基土不排水强度的各向异性、竖向荷载水平对于浅基础在H-M荷载空间内的破坏包络面的影响。首先进行浅基础分别在竖向、水平与力矩荷载单独作用下极限承载力的计算,并与已有结果进行对比。进而对于不同竖向荷载水平下浅基础在H-M荷载空间内的破坏包络面特性进行分析。计算结果表明：当浅基础埋深与宽度之比较大或基础承受三维自由度加载时,swipe加载模式得到的加载路径比真实的破坏包络面明显偏小;对于给定埋深的浅基础,其包络面的大小与地基土强度的各向异性与竖向荷载水平都有关系,而在归一化荷载平面内,包络面形状主要受到竖向荷载水平的影响,而与地基土强度的各向异性无关。     

基于遗传算法的建设工程风险决策多目标优化研究

在建设工程风险决策过程中,只考虑单个目标因素的决策并不能满足实际工程的要求。为了使决策更加科学、合理,在风险识别和风险评价的基础上,综合考虑包括风险管理成本在内的多个目标因素对决策结果的影响,建立了工程风险多目标决策优化模型,通过多目标遗传算法NSGA-Ⅱ,实现了工程风险决策方案的优化。最后,对优化结果的分析和评价,证明了所建立的模型在解决工程风险决策问题上的有效性和实用性。     

一种抗辐射危害和缓解视疲劳保健食品的研制

目的研制既能防止辐射危害又能缓解视疲劳的保健食品。方法以枸杞、菊花和葡萄籽为原料，经科学配伍加工制作，并进行毒理实验和功能评价。结果制成保健食品片剂。结论此产品具有抗辐射危害和缓解视疲劳的作用，安全无毒，可长期服用。