PET/PBT共混物和P(ET—BT)共聚物化学结构的各种分析方法研究

本文用红外光谱(IR)、核磁共振氢谱(~1H-NMR)、核磁共振碳谱(~(13)C-NMR)、差示扫描量热谱(DSC)、裂解色谱(PGC)和化学降解色谱(CDC)研究了PET/PBT共混物和P(ET-BT)共聚物的化学结构及其热转变,讨论了各种方法的适用性。结果表明,PGC和CDC法是组分分析最可靠的方法。~(13)C-NMR法是鉴别共混和共聚链结构的最有效手段。对于组分比的测定,CDC法最灵敏,PET和PBT的检测极限为0.5％,相对标准偏差<1％。     

锭尖球面超精加工中单片微机的应用

本文根据锭尖球面超精加工工艺对控制电路的要求,指出传统的由继电器、接触器组成的控制电路存在的缺陷及其原因,提出了应用单片机系统对锭尖球面超精加工进行控制的新方案,并详细地介绍了单片微机在超精加工机械上的检测和控制技术及其实际系统的组成,给出了程序框图;同时指出了为确保满足超精加工工艺要求所采用的一系列行之有效的硬、软件抗干扰措施。实践证明由单片微机系统对锭尖球面超精加工进行控制克服了原控制电路的缺陷,保证了加工台平稳动作、精确定位,满足超精加工工艺要求,并从多方面优化了整个机械的性能。     

Hot compressive deformation behaviors of Mg–10Gd–3Y–0.5Zr alloy

In this paper, the hot compressive deformation characteristics of a Mg–10Gd–3Y–0.5Zr(GW103K) alloy have been investigated by isothermal compression test at the temperature range of 350–450°C and strain rate range of 0.0001–0.1s~(-1). True stress–strain relationships at various strain rates showed the typical strain hardening and softening stage which is indicative of dynamic recrystallization during deformation. The results showed that the peak stress was obviously dependent on temperature and strain rate. A constitutive equation to describe the deformation process was established based on the hyperbolic sine function. The stress exponent n and apparent activation energy Q were determined to be 3.018 and 203.947 k J/mol, respectively. Microstructure investigation showed that dislocation slipping was the dominant deformation mechanism during the hot deformation at all conditions. However, at the temperatures lower than 400 °C and strain rates higher than 0.01 s~(-1), twinning was observed to be activated, which indicated another deformation mechanism. Dynamic recrystallization and dynamic precipitation were found to occur simultaneously under such deformation condition.     

基于力学响应的全厚式高模量沥青路面结构组合及优化

为了分析高模量沥青混凝土在全厚式沥青路面中的合理层位及使用情况,基于山东省典型全厚式沥青路面结构,通过构建全厚式沥青路面结构数值模型,分别将高模量沥青混凝土置于下面层、基层、底基层、基层+底基层、下面层+底基层及不设置高模量沥青混凝土六种工况,分析了各工况条件下力学响应指标的差异,以力学响应改善率为指标确定高模量沥青混...     

基于文献分析的罗汉果产业技术研究进展

为助力广西罗汉果(Siraitia grosvenorii)特色产业高质量发展,本文以国内外图书、期刊学术论文、学位论文、会议论文、专利技术、标准技术、科技成果登记等技术文献分析罗汉果产业技术研究现状,以科技奖励获奖情况分析行业技术的“尖锋”发展情况,从罗汉果的品种选育与繁育、种植栽培、深加工技术、应用开发等方面分析近3年的罗汉果行业热点,全方位、多角度、有针对性地综述罗汉果产业技术研究进展,并分析罗汉果产业技术的不足之处,以期为广西罗汉果产业的研究方向和发展规划提供参考。     

基于需求预测信息共享的竞争性企业联盟结构

构建联盟是企业应对市场需求不确定性和避免过度竞争的重要战略选择,由于企业间的差异性,如何根据市场竞争环境和需求预测精度选择合适的联盟伙伴,是企业决策过程中值得重视的问题.构建了一个包含3个竞争性企业的单层供应链,在不确定性需求下,企业间可以共享需求信号,从而降低需求不确定性和竞争强度.考虑到各企业预测精度的异质性和联盟...     

浅析老路改建路槽底面的处治

针对改建公路工程路槽底面的土壤含水量较高的不良地质情况,结合实际,采用不同的处治方法;通过弯沉、回弹模量等理论计算,确定路槽底面的处治深度,避免处理的盲目性,并采取石灰改善、选用合适的滤水性材料等手段,节约成本,降低造价,加快工程进度。     

铅黄铜复合分离法除Pb工艺探讨

简述了目前国内外铅黄铜除Pb工艺的现状,在分析复合分离法除Pb的理论基础上得出了Ca元素除Pb的可行性.归纳总结了Si-Ca及Mg-Ca除Pb剂对除Pb效果的影响及对除Pb后合金性能的影响.Si-Ca除Pb剂除Pb后,黄铜熔体中的Pb脱除率达到83%,但除Pb后黄铜基体中Si含量超标;Mg-Ca除Pb剂除Pb后,黄铜熔体中的Pb脱除率达到77.3%,基体中添加的Mg与Cu形成Cu₂Mg金属间化合物,在切削过程中起到与游离Pb相似的润滑、断屑作用,从而实现铅黄铜的脱Pb及再生环保易切削黄铜的开发.     

装饰用铜基仿金合金研究进展

装饰用铜合金尤其是仿金铜合金由于外表大方美观、光泽度好而深受追捧.但是受环境因素的影响,合金受汗液或二氧化硫等腐蚀气体腐蚀后,表面美观度大受影响.因此仿金合金的金色度、耐腐蚀和抗变色等综合性能的研究尤为重要.介绍了铜基仿金合金与黄金色度相近的物理学原理,以及利用CIE LAB色空间分析计算仿金合金色度的方法;综述了仿金合金的国内外研究现状,指出仿金合金的研究主要集中于耐腐蚀和抗变色方面;阐述了Zn、Al、Sn、Si、In等合金元素对仿金铜合金色度和抗变色行为的作用及其影响机理.     

Experimental study of the flow and heat transfer of a gas–water mixture through a packed channel

Waste heat recovery from the flue gas of gasfired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue gas.The experiments measured the effects of inlet air temperature, inlet air velocity and circulating water flow rate on the flow and heat transfer. The results show that higher inlet air temperatures and lower inlet air velocities lower the flow resistance and increase the heat transfer coefficient. The stainless steel packing had better surface wettability and larger thermal conductivity than the plastic packing, which enhanced the heat transfer between the water and the saturated moist air. When both the flow resistance reduction and the heat transfer enhancement were considered, the experimental results gave an optimal packing-specific surface area. A packed heat exchanger tower was designed for waste heat recovery from the flue gas of gas-fired boilers based on the experimental results which had better flow and heat transfer characteristics with lower pump and fan power consumption, more stable system operation and less thermal fluctuations compared with a non-packed heat transfer system with atomized water.