电磁起重机调磁保磁系统常发故障及改进

介绍了电磁起重机在马钢H型钢厂的应用情况,阐述了调磁保磁系统的作用和功能。针对在实际使用过程中的常发故障,进行了分析和改进。     

渤海大厚层油藏剩余油分布规律及挖潜实践

针对X油田纵向及平面水淹不均、剩余油分布规律复杂等问题,从层内、层间及平面等角度进行研究。研究认为,层内水淹受韵律性及重力共同作用,层间水淹受层间夹层影响,平面水淹规律受沉积相带控制。纵向上剩余油分布于各小层顶部,平面上主河道侧向、断层附近、潜山井区等剩余油富集。采取油井转注实现井网重塑、增加新井完善注采井网等针对性挖潜策略,在实践中取得了显著效果。     

浅析安徽地方文庙的布局特征——以寿州孔庙为例

儒学被认为是古代封建文化的正统,地方文庙也随着封建统治者对尊孔祭祀活动的升级而逐渐普及。寿州孔庙建筑群是安徽省境内始建年代较早,现存较为完整的地方文庙代表。本文以寿州孔庙建筑群为例,从特点鲜明的建筑组成,庙学合一的功能组织,礼制规范的形制格局,层层递进的序列空间等方面解析作为地方文庙建筑的典型布局特征,以期为安徽地方文庙建筑的保护研究提供参考。     

一种采用单双跳变的低功耗确定性BIST方案

为实现低功耗和高故障覆盖率,基于单跳变测试技术和2-bit扭环计数器,提出一种新型的单双跳变的确定性测试向量产生器.首先,与一般的确定性测试方案直接存储确定性种子不同,利用ROM存储控制信号并通过单双跳变生成确定性种子和确定性测试向量,这样控制信号的长度约为确定性种子的1/2,有利于降低功耗并节约存储空间.其次,2-bit减法计数器合理地过滤了冗余向量,大大缩短了测试时间并降低总体能耗.最后,为了适应不同的测试需求,还设计了相应的测试向量压缩算法和三种x指定算法.实验结果表明,平均功耗分别降低了42.36%、32.32%、38.94%,测试长度分别减少了77.6%、86.1%、84.3%,测试数据分别压缩了79.4%、65.2%、68.1%.     

Microstructure and erosion resistance of in-situ SiAlON reinforced BN-SiO<Subscript>2</Subscript> composite ceramics

BN-SiO₂-SiAlON composite ceramics were successfully prepared by the means of hot pressed sintering. Xe plasma flow generated by Hall Thruster was used for sputtering the surface of the samples in order to evaluate the plasma erosion resistance. XRD, TEM, SEM, and LSCM were used to characterize the phase composition and morphologies of as-made composite ceramics before and after Xe plasma erosion. The ceramics were composed of h-BN, fused silica, and SiAlON, which maintained structural stability during the process of Xe plasma sputtering. In conclusion, comparing with BN-SiO₂ composite ceramics, the plasma erosion rate of BN-SiO₂-SiAlON composite ceramics decreases significantly at first then rises with the increase of AlN addition. Erosion pits can be observed by using SEM on the surface after plasma sputtering, which demonstrates that the BN grains have dropped off the surface. In addition, mechanical denudation by high-speed Xe ions is recognized as the injury mechanism for the BN-matrix composite materials.     

Effect of pore structures on the electrochemical performance of porous silicon synthesized from magnesiothermic reduction of biosilica

Two kinds of porous silicon(PS) were synthesized by magnesiothermic reduction of rice husk silica(RHS) derived from the oxidization of rice husks(RHs). One was obtained from oxidization/reduction at 500 ℃ of the unleached RHs, the other was synthesized from oxidization/reduction at 650 ℃ of the acidleached RHs. The structural difference of the above PS was compared: the former had a high pore volume(PV, 0.31 cm3/g) and a large specific surface area(SSA, 45.2 m~2/g), 138 % and 17 % higher than the latter, respectively. As anode materials for lithium ion batteries, the former had reversible capacity of 1 400.7 m Ah/g, 987 m Ah/g lower than the latter; however, after 50 cycles, the former had 64.5 % capacity retention(907 m Ah/g), which was 41.2 % higher than the latter(555.7 m Ah/g). These results showed that the electrochemical performance of PS was significantly affected by its pore structures, and low reduction temperature played the key role in increasing its porosity, and therefore improving its cycling performance.     

基于FANP的私用飞行驾驶员安全驾驶行为评价模型

为了正确评价私用飞行员的安全驾驶行为,在系统分析飞行运行全过程的基础上,建立了基于模糊网络分析法(FANP)的私用驾驶员安全驾驶行为评价模型.针对模型中三角模糊数互补判断矩阵一致性检验过于复杂的问题,引入了最小方差的非线性规划模型,通过求取最优解以简化计算,获得可信度较高的评价指标权重.以某航校飞行学员的评价为实例进行实证分析,结果表明,该模型较传统评价方式更全面、客观,有助于飞行员的安全驾驶行为训练.     

紧固件表面锰系磷化膜的制备及摩擦磨损性能

为了提高核主泵紧固件的摩擦磨损性能,采用三种磷化工艺在40Ni Cr Mo7钢表面制备了锰系磷化膜.采用多功能材料表面性能测试仪进行了往复摩擦磨损试验,并研究了在有无润滑条件下,不同工艺对磷化膜摩擦磨损性能的影响.采用扫描电子显微镜和能谱仪表征了磨损前后磷化膜表面的组织形貌和化学成分,并分析了其磨损失效机制.结果表明,通过工艺Ⅱ制备的磷化膜具有最优的摩擦磨损性能.磷化膜特有的孔隙结构具有储油能力,有利于改善其摩擦学性能.随着法向载荷的增加,磷化膜的塑性变形增大,抗剪切强度降低,且摩擦系数呈先缓慢下降后急剧上升的趋势.     

Mechanical properties and microstructure of Portland cement concrete prepared with coral reef sand

The feasibility of using coral reef sand (CRS) in Portland cement concrete is investigated by testing the mechanical property and microstructure of concrete. The composition, structure and properties of the CRS are analyzed. Mechanical properties and microstructure of concrete with CRS are studied and compared to concrete with natural river sand. The relationship between the microstructure and performance of CRS concrete is established. The CRS has a porous surface with high water intake capacity, which contributes to the mechanical properties of concrete. The interfacial transition zone between the cement paste and CRS is densified compared to normal concrete with river sand. Hydration products form in the pore space of CRS and interlock with the matrix of cement paste, which increases the strength. The total porosity of concrete prepared with CRS is higher than that with natural sand. The main difference in pore size distribution is the fraction of fine pores in the range of 100 nm.     

不同粒径砂土的细观离散元模拟

基于离散元理论,建立砂土数值模型,并赋予颗粒微观参数进行三维数值模拟.通过大量的颗粒流数值试验,对颗粒微观参数进行调整,得到与室内三轴实验相一致的应力应变曲线.通过改变颗粒微观结构,结果表明颗粒直径对材料的宏观力学行为有比较明显的影响.实验突破室内常规三轴实验的局限性,揭示了微观规律,对以后的岩土工程的颗粒模拟提供了有价值的参考.