微地震信号的关联维

为了得到微地震信号的关联维特征,计算了原始信号中噪声段和微地震脉冲段的关联维.结果表明:随着嵌入维数的增大,噪声段的关联维数逐渐减小,最终趋于0,表明微地震记录中的噪声信号的吸引子为0;微地震脉冲段的关联维则在达到最小值后再次增大,其值在一定的范围内,表明存在吸引子,噪声段和微地震脉冲的关联维特征明显不同;选择适当的相空间重构参数,可以得到更好的结果.     

基于模糊规则的电弧炉三相电流解耦控制分析与研究

针对电弧炉电极调节系统的三相电流的强耦合对冶炼时间、电耗及产品质量等的不利影响,提出用模糊规则的方法进行解耦控制,从而缩短调节时间,节能降耗,避免电极震荡并减少对电网电压的影响,同时也有利于电极调节系统控制。仿真结果表明对三相电流中的一相突加扰动时,另两相超调由40%降为10%,震荡次数由两次减为一次。     

两类省煤器烟侧流动的CFD分析

利用CFD软件对光管及膜式省煤器横截面流场分布进行计算，利用流场速度分布图结合理论分析直观地比较两种省煤器在防磨、防积灰以及换热等性能上的优缺点，为各类锅炉选择合适的省煤器类型提供参考依据。     

Synthesis and microwave dielectric properties of Si/C/B powder

Si/C/B powders were synthesized by carbothermal reduction of xerogels containing boride. Colorless, transparent and monolithic gel was obtained by using tetraethoxysilane, saccharose, tributyl borate, ethanol and distilled water as starting materials. When the xerogel was fired at 1 600 ℃ in the static argon atmosphere, the XRD pattern commences to show the crystallite peak corresponding with C. β-SiC was synthesized at 1 700 ℃, but amorphous remainders could not be eliminated completely. The XRD results show that the boron possibly enters into the silica network, leading to the formation of borosiloxane. Microstructure offl-SiC powders consists of agglomerated particles with diameters ranging from 30 to 100 nm. Though the samples prepared at 1 600 ℃ and 1 700 ℃ have better dielectric loss tangent than the sample at 1 500 ℃ due to exiting crystalline material, the dielectric constant and dielectric loss tangent of three samples reveal lower values.     

ZnO粉体的固相法合成及微波介电性能

采用固相反应法制备了ZnO前驱体,在不同煅烧温度和保温时间分解得到ZnO粉体.用扫描电镜和X射线衍射仪表征合成粉体.采用矢量网络分析仪测试ZnO粉体在8.2～12.4 GHz的微波介电性能.结果表明:在不同煅烧温度和保温时间,前驱体均分解生成ZnO粉体.低温时,得到的样品颗粒大小均匀一致;随着温度的升高,颗粒逐渐长大,但均匀性变差.保温时间对样品颗粒大小的影响不明显.样品介电常数的实部(ε')和虚部(ε')随温度的升高先增大后减小,700℃时,达到最大;而随保温时间的增加,ε'和ε'的变化不显著.对产生介电损耗的机理进行了讨论,并提出改善介电性能的途径.     

溶胶-凝皎-碳热还原法制备富碳β-SiC纳米粉体

采用溶胶-凝胶-碳热还原法,以正硅酸乙酯和蔗糖为原料,在0.1 MPaAr气气氛中碳熟还原合成β-SiC纳米粉体.通过x射线衍射,Raman光谱、扫描电镜和透射电镜对β-SiC纳米粉体的物相、微观结构及形貌进行了表征.结果表明:当合成温度为1 600℃时,已经开始生成β-SiC相,随着温度升高至1 700℃,完全生成了含有Csi缺陷的富碳β-Sic相.β-SiC纳米粉体表现为纳米级的团聚颗粒,平均粒径为40nm,并生成晶须.对β-SiC纳米粉体的碳热还原反应机理进行了分析,结果表明:溶胶-凝胶法明显降低了生成气态SiO控制反应的温度.     

短切SiC纤维含量对SiCsf/LAS复合材料性能的影响

用热压烧结法制备了不同纤维含量的SiCsf/LAS玻璃陶瓷复合材料,研究了该复合材料的微观结构、力学性能和微波介电性能。结果表明:随着SiC纤维含量的增加,SiCsf/LAS材料的抗弯强度先增加后降低,最大值为104MPa。由于碳界面层的形成,SiCsf/LAS比LAS具有更高的介电常数。当SiC短切纤维的质量分数为1.5%时,SiCsf/LAS复合材料介电常数具有最大值,其实部ε′和虚部ε″均值分别为48和66,并具有明显的频散效应。     

空心微球表面化学镀Ni薄膜的工艺研究

比较空心微球表面化学镀Ni薄膜的工艺。分别以Sn-Pd胶体溶液和[Ag（NH3）2]^＋溶液作为活化剂，将空心微球表面进行活化，再采用化学镀的方法分别在其上淀积金属Ni薄膜。使用扫描电子显微镜（SEM）、能量色散光谱（EDS）和X-射线衍射光谱（XRD）对两种工艺所镀Ni薄膜的表面微观结构和组分进行表征。结果表明：用Sn—Pd胶体溶液活化后的空心微球表面淀积了均匀、致密的金属Ni薄膜，该薄膜是由大小约100nm的颗粒组成；而以[Ag（NH3）2]^＋溶液活化后的空心微球表面淀积的金属Ni薄膜，是由大小约1μm的颗粒组成。并分析了这两种镀层形成的机理。     

Synthesis and microwave dielectric properties of boron doped SiC powder by sol-gel method

Nano-SiC powders doped by B were synthesized through the carbothermal reduction of xerogels containing the tributyl borate. The results show that the 3C-SiC with minor phase of 6H-SiC is generated at 1 700℃, and that there are not the characteristic peaks of any boride in the XRD patterns, which indicates that the boron is available only on the crystallization of 3C-SiC. The Raman spectra of the samples also show the characteristic bands of 3C- and 6H-SiC at 788 and 965 cm^-1. But the bands at 1 345 and 1 590 cm^-1 are characteristic peaks of amorphous carbon materials. The intensities of peaks at 788 and 965 cm increase with B content in Raman spectra, which also shift to higher wavenumber with the increasing B. The microstructure of SiC powder is composed of agglomerated particles with diameters ranging from 30 to 100 nm. The results of dielectric property show that the sample with 0.005 B has the largest values in e＇ and ε＂ among the four samples due to the existence of the intrinsic defects. But the absence of the relaxation polarization leads to low values of all the samples.     

TiO2薄膜的椭圆偏振光谱研究

采用溶胶-凝胶工艺制备TiO2薄膜.XRD结果表明所制备TiO2薄膜为锐钛矿结构.场发射SEM结果显示TiO2薄膜致密、无裂纹,晶粒尺寸约为60～100 nm,单层薄膜厚度约为50 nm,且膜厚随着热处理温度的升高而增大.采用椭圆偏振光谱仪测试了薄膜的椭偏参数ψ、△与波长λ的色散关系,选用Cauchy模型对TiO2薄膜的折射率、消光系数和厚度进行了拟合.结果表明当波长大于800 nm时,TiO2薄膜的折射率在2.09～2.20左右,消光系数约为0.026.并对不同热处理温度下制备的TiO2薄膜光学常数及厚度进行了分析讨论.