基于视频数据和传递熵的鱼群信息传递网络构建

鱼群中的个体如何通过信息传递从而达到一致的群体运动状态,至今还没有刻画这一现象的统一数学模型.本文阐述了一种利用视频数据和传递熵构建鱼群中个体间信息传递网络的方法.首先用实验获取斑马鱼集群的视频数据,并采用计算机视觉跟踪的方法获取鱼群中每个个体的位置和运动速度,然后利用传递熵计算个体两两之间的信息传递关系,在此基础上构建了鱼群信息传递网络.通过网络分析,揭示了鱼群中个体间的信息交互个数与信息传播速度之间的关系,进一步发现了鱼群信息传递网络中的频繁子结构.本文提供了一种利用探测时间序列间因果关系建立鱼群信息传递网络的方法,为鱼群信息传递研究提供了一种新的思路.     

电力系统一二次调频的反馈微分博弈协同控制

风能等间歇式能源并网将是未来电网发展趋势,其输出功率的波动将加剧一二次调频之间的冲突反调问题.本文将反馈微分博弈应用于电力系统频率控制中,建立起一二次调频的协同控制模型,并考虑调速器死区、控制动作幅值限制、机组爬坡速率约束等工程实际因素,用协同进化算法求得该模型的反馈纳什均衡解.用仿真验证了该方法在满足各种工程因素下有效解决一二次调频的冲突反调问题,充分挖掘了系统蕴藏的调频能力.     

Some Insights into the Preparation of Pt/γ-Al2O3 Catalysts for the Enantioselective Hydrogenation of α-Ketoesters

Pt/γ-Al₂O₃ catalysts were prepared by two different impregnation methods and characterized by XRD, TEM, and CO chemisorption. The Pt particle sizes ranged in 2.4–23.3 nm for these 5.0 wt% Pt/γ-Al₂O₃ catalysts. The catalysts were also characterized by FT-IR spectroscopy using CO as a probe molecule before and after the chiral modification with cinchonidine. Two IR bands (2078 and 2060 cm^-1) due to CO linearly adsorbed on the Pt/γ-Al₂O₃ catalyst, calcined at 500 °C before reduction in sodium formate solution were observed, whereas only one IR band at ～2070 cm^-1 was observed for other catalysts. A red shift of the IR band was observed after chiral modification of all the catalysts, except the one with the largest Pt particle size and lowest Pt dispersion. The catalytic performance of the cinchonidine-modified Pt/γ-Al₂O₃ catalysts was tested for the enantioselective hydrogenations of ethyl pyruvate and ethyl 2-oxo-4-phenylbutyrate (EOPB). A 95% ee value was obtained for the ethyl pyruvate hydrogenation and about 83% ee was achieved for the enantioselective hydrogenation of EOPB under the optimized preparation and reaction conditions. It is deduced that the interaction of Pt with γ-Al₂O₃ is a crucial factor for obtaining high activity and that the adsorption abilities (adsorption of reactant, solvent and chiral modifier molecules) of the catalyst surface affect the catalytic performance significantly.     

Effects of an organic phosphorus nucleating agent on crystallization behaviors and mechanical properties of poly(propylene)

The effects of an organic phosphorus nucleating agent on the crystallization behavior and mechanical properties of poly(propylene) were investigated. As the concentration of nucleating agent increased from 0 to 0.8%, the tensile and flexural strengths of the nucleated poly(propylene) resin increased by 15%, the flexural modulus increased by 35%, the crystallization peak temperature increased by 10°C, and the nucleation density (calculated with the nonlinear Voltrra integral equation) increased by 10⁶ times. Mechanical properties increased with nucleation density. Linear equations between the mechanical properties and the logarithmic nucleation density were revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 297–301, 2003     

硫酸氢钠催化合成丁二酸二乙酯

在一水硫酸氢钠存在下 ,由乙醇和丁二酸合成了丁二酸二乙酯。当丁二酸、乙醇和硫酸氢钠的物质的量比为 1∶ 6∶ 0 .2 ,环己烷为溶剂 ,回流分水 5 0 m in,酯收率达 80 .5 %     

基于解码缓冲信息的IPTV QoE策略

提供一种可在IPTV用户的终端接收设备上评测QoE(Quality of Experience)的方法。该方法通过实时监测设备上的解码缓存的状态以及缓存中的媒体丢失率作为参数,并基于统计和实验数据建立这些参数和QoE的函数关系,最终给出它们之间的推算公式来量化当前流媒体视频的QoE等级(MOS值)。考虑到终端设备(如IPTV机顶盒)的处理能力在应用中还会对相应方法做一些优化。     

双环戊二烯改性不饱和聚酯树脂研究进展

较详细地介绍了双环戊二烯改性不饱和聚酯树脂的机理、合成路线(初始法、半酯化法、酸酐法、后期法、封端法和水解法)及国内外双环戊二烯改性不饱和聚酯树脂在气干性、低苯乙烯挥发、低收缩性与力学性能方面的研究进展,提出了今后的研究方向。     

冲压式舵机动态特性测试系统的研制

为了在实验室条件下模拟冲压式舵机的舵面在空中所受的气动载荷,实现舵机系统动态性能指标的综合检测,设计了基于PXI总线的舵机动态测试系统,工作过程中对舵偏角信号、工作电流信号、扭矩信号进行实时采集、显示,并配合测试流程完成对舵机动态性能的测试。设计中重点考虑了定刚度加载系统的小扭矩加载精度、小转动惯量以及同轴度问题。实验结果表明,该测试系统测试精度高、使用维护方便,满足要求。     

多孔β-TCP陶瓷药物载体结构与性能的影响因素

本分析了影响多孔β-TCP陶瓷药物载体结构与性能的因素，确定了制备多孔β-TCP陶瓷药物载体的技术路线和工艺参数。     

恒粘天然橡胶理化性能的研究

用粘度稳定剂处理天然橡胶鲜胶乳和湿杂胶，研究了粘度稳定剂种类及处理方法对橡胶的P0、PRI、MV、氮含量和加速贮存硬化值（△P）等的影响。结果表明，鲜胶乳所制得的恒粘胶经加速贮存后的△P≤1个塑性值，门尼粘度值变化量（△MV）≤3个门尼值。其它性能虽有变化，但均能达到天然生胶标准的要求。自然凝固制得的恒粘胶的P0、PRI和MV相对较高，氮含量相对较低。粘度稳定剂延长了鲜胶乳的凝固时间。粘度稳定剂处理后的杂胶，△P和△MV减少，但恒粘效果不及鲜胶乳制得的恒粘胶。