造孔剂及烧结温度对堇青石支撑体性能的影响

以人工合成堇青石粉为原料,使用碳粉、淀粉、聚苯乙烯微球为造孔剂,采用挤压成型和固态粒子烧结法制备多孔堇青石陶瓷支撑体.研究了造孔剂种类、用量及烧结温度对支撑体开孔率、抗压强度、空气渗透速率等性能的影响,并用XRD和SEM分析了不同造孔剂对样品的物相组成及断面形貌的影响.研究结果表明:添加造孔剂不会改变试样的物相组成,但对试样的基本性能影响显著,其中添加聚苯乙烯微球的试样开孔率最大,微孔间连通性最好,造孔效果最好;烧结温度能使材料致密化,可以有效提高抗压强度,当温度为1300℃、添加10;的聚苯乙烯微球时制备出的支撑体性能最优.此时开孔率为53.81;,抗压强度为8.36 MPa,空气渗透速率为5.99 m3·h-1·Pa-1·m-2,耐碱腐蚀率为99.97;.     

表面涂覆CeO_2对Co－40Cr合金氧化行为的影响

研究了表面涂覆ＣｅＯ２对Ｃｏ４０Ｃｒ合金在１０００℃、空气中恒温氧化和循环氧化的影响。并用扫描电镜／能谱（ＳＥＭ／ＥＤＸＳ）、电子探针（ＥＰＭＡ）、高分辨电子显微镜（ＨＲＥＭ）等测试手段对氧化膜的形貌和成分进行了观察分析。此外，还用声发射（ＡＥ）方法对氧化膜在热应力作用下发生的开裂和剥落进行了监测。结果表明，涂覆ＣｅＯ２后极大地提高了合金的抗恒温氧化和抗循环氧化性能。研究表明，涂覆的ＣｅＯ２主要以细小颗粒的形式高度弥散存在于氧化膜的外表面，并且主要分布于氧化物晶界上，其中部分ＣｅＯ２以更加细小（１０～２０ｎｍ）的形式存在于Ｃｒ２Ｏ３晶粒内部。这些弥散分布的ＣｅＯ２颗粒改变了Ｃｒ２Ｏ３氧化膜的生长机制，通过阻碍Ｃｒ３＋阳离子向外扩散，降低了氧化膜的生长速率，细化了氧化膜的晶粒并提高了膜的高温塑性，使氧化膜在基体上有较好的粘附性     

三个矩阵秩不等式中等号成立的充分必要条件

研究了线性代数课程教学中三个矩阵秩的不等式,得到了不等式等号成立的充分必要条件.     

大滞后系统控制策略研究——动态矩阵控制的数字仿真

本文详细地从工程设计方面探讨了一种基于预测控制的控制算法，即动态矩阵控制（DMC），实践结果证明动态矩阵控制能很好地克服被控对象的大滞后特征。由于DMC有对模型精确度要求不高等众多优点，它可在石油化工、纺织、钢铁、冶金等行业得到广泛的应用，从而为企业带来更大的经济效益。     

以3,5-二甲基-1H-1,2,4-三氮唑及对苯二甲酸根构筑的三维锌配位聚合物的合成、晶体结构及荧光性质(英文)

水热法合成了1个新颖的锌配位聚合物{[Zn3(Hdmtrz)2(1,4-bdc)3]·2H2O}n(1,Hdmtrz=3,5-二甲基-1-H-1,2,4-三氮唑,1,4-bdc=对苯二甲酸根),对其进行了红外光谱、元素分析、X射线粉末衍射和热重分析等表征,并用X-射线单晶衍射法测定了配合物的单晶结构。该配合物属三斜晶系,P1空间群,晶胞参数为a=0.917 97(18)nm,b=0.983 3(2)nm,c=1.071 7(2)nm,α=100.81(3)°,β=102.589(3)°,γ=106.90(3)°,V=0.8418(3)nm3,Z=1。该化合物为三维框架结构,拓扑类型为pcuα-Po简单立方格子,Schl覿fli符号记为{412·63}。室温固态荧光测试显示,配合物在471 nm(λmax)具有强的荧光吸收。     

高中数学课堂“小组合作讨论”中有效提问的策略研究

研究问题的起因:新课程的理念是以人为本,体现这一理念就要求学生更多地参与到教学活动中,小组合作学习的教学模式可使学生人人参与学习过程,人人得到锻炼的机会,培养学生集体合作的精神,它的有效运用成为体现新课程改革精神的重要标志之一.近两年在淳安县第二中学也实行了"高效合作小组"分组制,每个班根据各班的实际情况,每组六人左右,每组要有优等生、中等生和学困生且都有小组长,小组长的学习成绩     

一个包含Smarandache函数及第二类伪Smarandache函数的方程

主要研究方程Z2（n）＋1=S（n）的可解性,利用初等方法以及Smarandache函数的性质,证明了该方程有无穷多个正整数解,并获得了所有正整数解的具体表现形式．     

一类完全非线性函数的原像分布

利用代数数论的有关知识与理论,研究了从3l阶交换群到3阶交换群上完全非线性函数的原像分布特征方程,通过讨论其等价方程x2+xy+Y2=l的整数解问题,给出了该类完全非线性函数存在的必要条件及其原像分布特征的计数.进一步给出了求该类完全非线性函数所有可能原像分布特征的一个算法.     

Calculation of infrared properties of low emissivity coatings containing metallic flake pigments

The infrared emissivity of low emissivity coating can be significantly reduced by adding high content concentrations of parallel distributed metallic flake pigment. However, the infrared emissivity is very difficult to calculate by the existing theory models, such as the light scattering theory and traditional Kubelka-Munk radiative transfer model, because of shape and distribution anisotropy of flake pigments. Thus, the low emissivity coating is assumed to be the superposition structure of homogeneous layers and metallic flakes are approximately uniform and parallel arrangement in each layer. Based on geometric optics theory and Kubelka＇s layer model, considering multiple reflection, transmission and absorption of infrared radiation among different layers, the theoretical model is established to calculate the coating emissivity. The facts of binder, pigment concentration and thickness are also systematic discussed. The result shows that the law of influence on infrared emissivity can be correctly simulated by this theoretical model. Transparent binder, high volume concentration of thin flake pigment can facilitate to reduce infrared emissivity. Moreover, this model offers the possibility of predicting the infrared optical properties of coatings by their optical constants.     

Mssbauer studies on the shape effect of Fe_(84.94)Si_(9.68)Al_(5.38) particles on their microwave permeability

Ball milling for long time (such as 10, 20, and 30 h) can transform Fe 84.94 Si 9.68 Al 5.38 alloy powders with irregular shapes into flakes. X-ray diffraction (XRD) and Mssbauer measurements have proven that the unmilled particles and the flakes obtained by milling for 10 h have the same D0 3 -type superlattice structure. The flakes obtained by milling for 20 h and 30 h have the same disorder α-Fe(Si, Al) structure. There are more than 6 absorption peaks in the transmission Mssbauer spectra (TMSs) for the particles with D0 3 -type superlattice structure, which can be fitted with 5 sextets representing 5 different Fe-site environments. However, only 6 TMS absorption peaks have been found for particles with a disorder α-Fe(Si, Al) structure, which can be fitted with the distributions of Mssbauer parameters (Bhf, isomer shift). The TMS results show that the flaky particles have a stronger tendency to possess the planar magnetic anisotropy. As the result, the flakes have larger microwave permeability values than particles with irregular shapes. The conversion electron Mssbauer spectra (CEMSs) also show the significantly different Fe-sites environments between the alloy surface and the inside.