水热法解聚钠硼解石制备硼酸钙

以钠硼解石天然矿粉为原料，经水热解聚和相转化制备出硼酸钙产品。通过化学分析、XRD及TG—DTG分析表明：产品中的物相主要是白硼钙石（4CaO·5B2O3-7H2O）、硬硼钙石（2CaO·3B2O3·5H2O）和羟硼钙石（3CaO·2B2O3·9H2O）。实验确定了适宜的工艺条件，即：反应体系液固体积质量比为2．5mL／g左右；解聚温度120℃；解聚时间8h左右；干燥温度在200℃左右。在此工艺条件下制得的硼酸钙产品的氧化钠质量分数在0．5％以下，很好地满足了无碱玻璃纤维工业对含硼原料的要求。     

最大熵和条件随机场模型相融合的藏文人名识别

藏文人名识别是藏文信息处理领域研究的难点之一,其识别效果直接影响到藏文自动分词的精度和相关应用系统的性能,包括藏汉翻译、藏文信息检索、文本分类等。该文在分析藏文人名构成规律和特点的基础上,提出了一种最大熵和条件随机场相融合的藏文人名识别方法。实验表明,该方法可以获取较好的识别效果,在我们的测试集上F-测度值到达了93.08%。     

Electrocatalytic activity of tungsten trioxide microspheres, tungsten carbide microspheres and multi-walled carbon nanotube-tungsten carbide composites

Tungsten trioxide micropheres were prepared by spray pyrolysis, and tungsten carbide microspheres were produced by spray pyrolysis-low temperature reduction and carbonization technology. Multi-walled carbon nanotube-tungsten carbide composites were prepared by the continuous reduction and carbonization process using multi-walled carbon nanotubes (MWCNTs) and WO₃ precursor by molecular level mixing and calcination. The morphology and structure of the samples were characterized by scanning electron microscope and transmission electron microscope. Furthermore, the crystal phase was identified by X-ray diffraction. The electrocatalytic activity of the sample was analyzed by means of methanol oxidation. Tungsten carbide microspheres were catalytic active for methanol oxidation reaction. Nevertheless tungsten trioxide microspheres and multi-walled carbon nanotube-tungsten carbide composites were not catalytic active for methanol oxidation reaction. These results indicate that tungsten carbide micropheres are promising catalyst for methanol oxidation.     

改进鱼眼变换技术的图像适应

目的 为解决目前基于鱼眼变换技术的图像适应方法难以解决的焦点检测和多焦点冲突两大问题,提出一种基于改进鱼眼变换技术的图像适应方法。方法 提出的方法根据源图像的能量计算出图像中所有最优高能量线并组成高能量线集合,作为源图像的高能量部分,即图像的焦点区域;以能量线而不是传统的图像区域为单位进行鱼眼变换以得到目标图像。结果 改变鱼眼变换技术的变换模式并应用于图像适应中,实验结果表明,本文方法解决了基于鱼眼变换技术的图像适应方法存在的问题,通过本文算法所得到的目标图像具有较好的视觉效果,用户满意度接近4分。算法运行速度较快,将源图像(512×384)长度缩小一半的情况下仅需6 s的运算时间。结论 本文方法一方面保留了鱼眼变换图像适应方法的优势,在突出显示图像重要部分的同时,不会忽略图像的次要部分;另一方面解决了鱼眼变换图像适应方法存在的焦点检测和多焦点冲突问题。实现效果和用户主观评价结果表明,该方法是一种有效可行的图像适应方法。     

Melting behavior and nonisothermal crystallization kinetics of polyamide 6/polyamide 66 molecular composites via in situ polymerization

The melting behavior and nonisothermal crystallization kinetics of pure polyamide 6 (PA 6) and its molecular composites with polyamide 66 (PA 66) were investigated with differential scanning calorimetry. The PA 6/PA 66 composites had one melting peak, whereas the coextruded PA 6/PA 66 blends had two melting peaks. With the addition of PA 66 to PA 6 via in situ anionic polymerization, the melting temperature, crystallization temperature, and crystallinity of PA 6 in the composites decreased. The half‐time of nonisothermal crystallization increased for a PA 6/PA 66 molecular composite containing 12 wt % PA 66, in comparison with that of pure PA 6. The commonly used Ozawa equation was used to fit the nonisothermal crystallization of pure PA 6 and its composites. The Ozawa exponent values in the primary stage were equal to 1.28–3.03 and 1.28–2.97 for PA 6 and its composite with 12 wt % PA 66, respectively, and this revealed that the mechanism of primary crystallization of PA 6 and PA 6/PA 66 was mainly heterogeneous nucleation and growth. All the results indicated that the incorporation of PA 66 into PA 6 at the molecular level retarded the crystallization of PA 6. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2172–2177, 2005     

铝阳极氧化膜孔内电沉积银及其抗菌性能

Aluminum specimens were anodized in a sulfuric acid bath, then silver was electrodeposited in pores of the anodized aluminum by using alternating current . The anodized aluminum with deposited silver was testedfor its antibacterial performance. The results show that the antibacterial rates of the specimens are above 95% against the growth of E. coil, P. aeruginasa, S. faecalis and S. aurens. The morphology of the silver in pores of anodized aluminum is characterized by transmission electron microscopy, and the micrographs indicate that silver is assembled in the form of nanowires with a diameter of 10 nm or 25 nm. The nanowires have a structure of parallel bright stripes alternating with parallel dark stripes.     

认知任务驱动的fMRI脑功能网络构建方法

针对脑功能网络的构建受到特定大脑图谱对兴趣点描述准确度及覆盖度的限制,提出了基于认知任务信息和神经影像数据的脑功能网络构建方法。首先计算fMRI体素对于认知任务的敏感度,然后在此基础上选取兼顾分布均衡和去中心化的大脑兴趣点,从而构建任务驱动的脑功能网络。实验通过在人脸情绪识别认知任务相关的梭状回构造任务驱动的脑功能网络,其度中心性、聚类系数、全局效率、局部效率这四个复杂网络指标均优于典型大脑图谱梭状回中兴趣点构成的网络。结果表明,计算得到的大脑兴趣点具有更强的整合性,更适合用于表征特定认知任务下的脑功能网络。     

考虑停车位不足的出发时刻选择问题

针对目的地停车位不足,出行者如何选择出发时刻的问题,在有限理性视野下综合考虑道路拥堵状况、出行者个人感知差异、目的地车位供给状况以及无法停入合法停车位后将受到惩罚等因素对出行者出发时刻选择的影响.依据前景理论设计实验,通过调查获取出行者出发时刻选择意向数据,构建出行者出发时刻选择模型.研究结果表明:停车位剩余状况影响出行者对出行结果的满意程度以及下一次出行决策.出行者出行结果满意度随着目的地剩余车位的减少而降低,当出行者的出行结果为满意时,出行者下一次出行由倾向于早到逐渐变为倾向于晚到.在车位不足,不能合法停车的情况下,不同的惩罚措施会影响到出行者下一次出发时刻的决策结果,惩罚越严重,出行者越倾向于早出发.     

不同尺寸段塞组合等流度二元驱驱油效果评价

辽河油田锦16块实施二元复合驱以来,仍存在部分注入井单层吸液量过大,使注入液在各层中的推进速度不一致,从而导致相应的采油井聚合物质量浓度上升较快的问题。通过室内驱替实验,采用均质岩心和非均质岩心,对比不同段塞组合的等流度二元驱驱油方法在非均质岩心上的驱油效果。结果表明,在相同聚合物用量和总注入孔隙体积倍数条件下,在三层非均质岩心上等流度驱油方法比常规单段塞驱油方法化学驱采出程度高出3.54%;多段塞等流度驱油方法可以明显提高中、低渗层分流率,降低高渗层分流率。因此,合理段塞组合等流度二元驱油方法可有效提高高渗透非均质油藏的采收率。     

Finite Element Simulation for Laser Direct Depositing Processes of Metallic Vertical Thin Parts（1）

建立了模拟直薄壁件逐点沉积过程中温度场的有限元模型，用等价导热系数和焓值法处理了固一液耦合热传导问题和固液混合区的焓．模拟结果真实地反映了沉积316L不锈钢直薄壁件的温度场特征．通过对模拟结果的分析得出，在高温阶段（700℃以上）熔池的平均冷却速率达到10^3℃／s数量级，在240℃以下的冷却速率仅为10℃／s数量级．基板的温度变化经历温度上升、温度平稳、温度下降3个阶段；在温度下降阶段，基板中的热传导对熔池冷却速率影响很小．有限元模拟结果与已有文献的实验测量数据吻合很好．