燃用准东煤电站锅炉灰沉积形成过程中的矿物演变与热力学模拟

选取某350 MW电站锅炉燃烧准东混煤,得到锅炉换热面灰沉积样品,主要借助XRD等手段分析了各处灰沉积物矿物形成过程,并通过Factsage 5.2从热力学平衡角度给出理论支持。结果表明,高温区域换热面灰沉积形成主要由于钠长石、钙长石等矿物在高温下经复杂变化形成低温共熔物,黏附烟气中固体颗粒而形成坚硬块状沉积物;低温区域换热面主要由于烟气中硫的沉积而发生酸性腐蚀,沉积物主要晶相为硫酸钙;省煤器换热面主要由于烟气携带的非晶态物形成松散型积灰。Factsage计算结果与实际灰样组成大致吻合,能够帮助分析灰沉积物中矿物质的转化规律。     

Tm:K2YF5晶体的光谱参量计算

测量了Tm:K2YF5晶体的吸收光谱,根据Judd-Ofelt理论计算了Tm3+在K2YF5中的强度参数:Ω2=5.02×10-20cm2,Ω4=3.40×10-20cm2,Ω6=0.38×10-20cm2,以及Tm3+激发能级的自发辐射跃迁几率A,荧光分支比β,荧光寿命τ和积分发射截面∑等光谱参量.     

DYNAMIC SPECTRAL ANALYSIS OF INFRASONIC SIGNAL WITH HILBERT TRANSFORM

In the past we analyzde the dynamic spectrum of infrasonic waves with FFT,but that isnot suitable to this analysis in any case.In this paper another method is proposed to analyzeinfrasonic waves.This method is that,after digital filtering of the signal and Hilbert transform,this paper the computation of the envelope with Hilbert transform and 1/12-octave filter are dis-cussed.Then a synthetic infrasonic signal generated by a large nuclear explosion is analyzed withthe two methods,and their results are compared.It is shown that,in the dynamic spectrum,usingHilbert transform,not only higher resolution is obtained,the main frequency range of separatedmodes can be achieved,but also their waveform can be obtained preliminarily for some modes.Thus it seems that in some cases this method is more efficient for discovering the characteristicsof an infrasonic signal.     

CHARACTERISTICS OF A UNIFORM PIPE ARRAY AND ITS APPLICATION TO INFRASONIC RECEPTION

In this paper the acoustic behaviour of a uniform pipe array,one end of which is connected to aninfrasonic transducer and the other is terminated with an acoustic impedance,is discussed.Both theo-retical analysis and computation of the response of the pipe array are given.Influenes of the impedan-ces at the terminal and of the transducer on the response are shown.By using these results the frequen-cy and phase responses and the directivity can be calculated as a plane sound wave pass across thearray. The pipe array is used for detecting the infrasonic or gravity waves in wind noise.A model of windnoise is established and its average power spectrum density function and coherence can be computed.Based on the theoretical analysis of the pipe array,some imporvement in the signal-to-noise ratioof infrasonic waves in the wind noise back-ground can be got by calculation.Results of a numericalexample obtained by computer programme are given.It is found that there is a significant improve-ment in the period range     

轴对称Poisson方程的Trefftz有限元解法

将径向基函数应用到一类轴对称Poisson方程的数值求解中,提出了一种Trefftz有限元计算格式.非0右端项将问题的特解引入Trefftz单元域内场,致使单元刚度方程涉及区域积分.利用径向基函数对特解近似处理,可消除区域积分,从而保持Trefftz有限元法只含边界积分的优势.为获得特解,选取求解域内所有单元的节点和形心作为基本插值点,而在求解域之外构造一个虚拟边界,在其上布置一定数目的虚拟点作为额外插值点.数值算例验证了该方法的有效性和可行性.     

多孔介质平板通道传热模型的两种求解方法

基于Brinkman Darcy扩展模型和非局部热平衡模型,考虑液相和固相含有内热源的情况,建立了多孔介质平板通道传热的一般模型.分别采用直接法和间接法将液相与固相能量方程解耦,进而求得充分发展传热条件下的多孔介质温度场.与直接解耦法相比,间接解耦法可在原始边界条件下求解二阶微分方程,更加简单易行.通过对无量纲温度表达式系数以及温度分布的比较,验证了两种求解方法的等价性.在两种极限情形下,间接法所得温度分布解析解与现有文献结果相当吻合,这也在一定程度上证明了所建模型更具一般性.参数分析表明,液固两相温差随着Biot数或有效导热系数比的增大而减小,Nusselt数随着内热源比的增大而减小.     

用于递模塑料的有机硅树脂

本文指出提高水解温度,或使用丙酮和甲苯混合溶剂,有利于甲基三氟硅烷与苯基三氯硅烷和二甲基二氯硅烷的共水解缩聚反应,而不易产生凝胶现象。并以此合成了适于递模塑料的R/Si较小、C_6H_5/R较低、羟基含量较高的羟基缩合型无溶剂树脂,简化了步骤,大大缩短了操作时间,树脂质量稳定。此外还讨论了树脂的结构与递模塑料性能的关系,选择了较好的固化剂以及通用的补强剂,使塑料具有优异的性能。     

嵌段共聚有机硅树脂的研究

以甲基三氯硅烷、苯基三氯硅烷、二甲基二氯硅烷以及羟基封头的聚二甲基硅氧烷,即HO[(CH_3)_2SiO]_nH,为原料,采用共水解的方法,合成了具有嵌段结构的有机硅树脂。 研究了树脂的结构与抗开裂性能的关系,确定了树脂链段与橡胶链段的克分子比例以及橡胶链段的长度,即n值的大小,该树脂具有优异的抗开裂性能,是一种较好的大功率半导体器件的封装材料。