大内跨小边跨框架结构预应力筋优化布置方法

预应力筋的优化布置是大内跨小边跨的多跨预应力混凝土框架结构合理设计计算的关键.为满足控制截面承载力最大的需要,以往常将大跨所需预应力筋布置为连续曲线,并按水平直线延伸通过其相邻的两小跨,按这种布置方式仅使大跨内产生竖向向上的预应力等效荷载,可较好平衡大跨的竖向外荷载;而若将大跨及相邻的两小跨统一考虑,预应力筋按连续曲线布置,张拉产生的预应力等效荷载不但可有效平衡大跨的竖向外荷载而且也可平衡小跨的竖向外荷载,可以使荷载平衡得到优化实现.以一典型工程为例,分析了在相同条件下两种预应力筋布置过程中张拉引起的综合弯矩、主弯矩和次弯矩的分布和量值上差异,比较了两类布筋形式对正截面承载力计算结果的影响,验证了对大内跨小边跨框架结构统一考虑后整体上按三段连续正反抛物线预应力筋布置的合理性.     

Bone Tissue Response to the Bone-like Tissue Coating on Titanium

The objective of this study was to investigate the effects of mineralized bone nodules, formed in vitro by bone marrow stromal cells(BMSCs), on the new bone formation in bone defect and on implant surface. The mineralized bone nodules were generated by culture of Lewis rats BMSCs on titanium disks in osteogenic induction medium. The gap-healing animal model was used to create the bone defect facing the disk. The titanium disks in the presence of B group or in the absence of NB group bone nodules were randomly placed into one of the rat distal femurs. This self-control design was used to compare the bone formation in defects and on titanium surface, by Micro-CT, fluorescence staining, histological and histomorphometric analysis. The new bone formation parameters in bone defect area of B group were significantly higher than those of NB group at 2 weeks, including bone volume fraction, trabecular thickness and bone area ratio. The bone nodules pre-stained with Alizarin red disappeared mostly at 2 weeks, while the red fluorescence reappeared in the newly formed bone away from the disk surface. For the bone-implant contact, B group showed lower values than NB group at 2 weeks, but no significant difference was found at 4 weeks. Our results indicate that the mineralized bone nodules can be resorbed in vivo and promote the early osteogenesis in the bone defects, and bone nodules may be applicable for new bone generation in bone defect or modification of tissue engineering scaffold.     

智能电网中电动汽车充电的自适应电价控制方法

针对电动汽车的充电提出一种电价控制策略。聚合管理者集中管理电动汽车的电池,并且考虑用电高峰时电网的电能供给有限,通过电价控制调整充电的需求量。采用自适应动态规划,通过在线网络训练,得到最优的电价策略。仿真结果表明,该自适应电价控制方法能够通过学习电动汽车的移动性和充电过程,从而调整实际充电需求量至期望水平,保证智能电网的稳定运行。     

动态网络中行业因素与股市波动性研究

股票市场的波动性一直是金融领域的一个研究重点,行业因素对股市波动性的影响也是投资者关注的一个焦点.从复杂网络视角出发,以行业内股票相关性强弱(RIL)为指标实证研究了行业因素与股票波动性之间的联系.研究发现不同行业的RIL指标有不同的参考标准,于是对原有的RIL指标进行了改进得到新指标RIL*.在以沪深300样本股为例的实证研究中发现采矿业、金融业和房地产业内的股票受行业因素影响最强.研究还发现股票网络结构变化和股市波动性之间存在联系,当行业因素影响急剧降低时,行业内的股票走势会猛烈上升或下降.     

基于改进Kendall-f算法的发电机定子温度分析

在线监测发电机定子温度可有效发现定子部分过热性故障,如何从检测的温度数据中提取反映定子故障预警的信息是目前国内外研究的热点。该文采用可变窗改进Kendall-f算法处理监测温度数据,提取其变化趋势特征信息;采用偏度分析提取监测温度异常值,从而正确诊断定子过热性故障,仿真分析及实验结果表明该方法有效提高了定子温度监测与预警的准确率。     

论土家织锦对巴楚文化的精神继承

土家织锦是身处巴楚文化长期融合与发酵区域的土家人对大自然和生活的一种艺术理解,反映了土家人生产生活的一种精神特质,更是体现了土家织锦对巴楚文化的精神继承。本文从西兰卡普的巴楚文化历史溯源出发,立足于史料记载和巴楚文化特征,通过西兰卡普中体现出的热烈奔放的浪漫风格、朴拙的审美情趣、兼容并蓄、果敢创新等文化精神内涵来分析与巴楚文化精神之间存在的共通性。     

2-（4-氯苯氨基）甲基苯酚降解的动力学研究

采用高效液相色谱技术,开展了Fenton试剂对2-（4-氯苯氨基）甲基苯酚（CMP）的氧化降解动力学的研究。考察了初始双氧水摩尔浓度、亚铁离子摩尔浓度和温度等因素对CMP降解速率的影响,结果表明,当双氧水摩尔浓度、亚铁离子摩尔浓度增大和温度升高时,CMP的氧化速率明显加快。在30~45℃的温度范围内,其氧化降解符合假一级反应动力学模型,反应的表观活化能Ea为102.90kJ/mol。     

嵌入式消毒柜门内衬板拉深模具设计

通过对嵌入式消毒柜门内衬板工艺分析，确定其模具加工方案，同时对试模过程中存在的问题作进一步的剖析。     

Electrochemical and microstructural characterization of cyclic redox behaviour of SOFC anodes

The oxidation of Ni to NiO in solid oxide fuel cell (SOFC) anode will result in large bulk volume change, which may change the interfaces of the two phases in the anode cermet and thus may cause significant performance degradation. The reduction and oxidation (redox) of the Ni/YSZ cermet were studied at 800 ℃. Anodic polarization measurements were performed before and after redox cycles. The anode current density at an overpotential of 100 mV kept decreasing during the whole redox treatment. It decreased from 19.11 to 7.95 mA·cm-2 after two redox cycles. Anode supported unit cell was assembled for cell's discharge measurements. Cell performance declined after each redox cycle. The maximum power density decreased from 126.28 to 40.32 mW·cm-2 . The microstructural changes after redox cycling were recorded using scanning electron microscopy (SEM). The results reveal that after re-oxidation, the Ni gets coarse and has a higher porosity; the nickel network structure turns to be desultory.     

THE FLOW STRESS OF ALLOY STRUCTURAL STEELS AT HIGH TEMPERATURE AND HIGH STRAIN RATE

采用恒应变速率凸轮式压缩试验机对8种合金结构钢的流动应力进行了实验研究。其变形温度(T)、应变速率((?))及变形程度(ε％)分别为850—1150℃,5—80s~(-1)及5—69％。分析了变形温度、变形程度及应变速率对流动应力(σ)的影响。通过对变形温度影响项具有两种表达式的流动应力数学模型的非线性回归分析及比较,提出了拟合精度较高的8个合金结构钢流动应力的数学模型,并给出了数学模型的回归系数值。