正交实验优化金银花中绿原酸的提取工艺

本研究选择以绿原酸作为考察指标,在单因素实验的前提下,通过正交试验,对液料比、提取时间、浸泡时间、提取次数对金银花提取率的影响进行了考察,结果显示最佳提取工艺为加15倍的水,提取3次,每次提取60 min,结果符合实际生产要求。     

Low-temperature-sintered Bi0.5Na0.5TiO3-based lead-free ferroelectric ceramics with good piezoelectric properties

Li₂CO₃ has been used as a sintering aid for fabricating lead-free ferroelectric ceramic 0.93(Bi_0.5Na_0.5TiO₃)-0.07BaTiO₃. A small amount (0.5 wt%) of it can effectively lower the sintering temperature of the ceramic from 1200 °C to 980 °C. Unlike other low temperature-sintered ferroelectric ceramics, the ceramic retains its good dielectric and piezoelectric properties, giving a high dielectric constant (1570), low dielectric loss (4.8%) and large piezoelectric coefficient (180 pC/N). The “depolarization” temperature is also increased to 100 °C and the thermal stability of piezoelectricity is improved. Our results reveal that oxygen vacancies generated from the diffusion of the sintering aid into the lattices are crucial for realizing the low temperature sintering. Owing to the low sintering temperature and good dielectric and piezoelectric properties, the ceramics, especially of multilayered structure, should have great potential for practical applications.     

基于资源路由器的网格资源管理系统

论述了实现网格资源管理系统所涉及到的各方面问题。论述的是一种基于资源路由器的网格资源管理系统。介绍了网格资源管理系统的组成及各组成部件的作用及网格资源管理中的3个关键技术,包括资源管理信息库管理、资源描述信息库管理、资源服务的接口设计。     

螺旋槽管中单相水与油湍流摩擦阻力与传热特性

对单相水与油分别在4根不同几何参数的螺旋槽管中湍流摩擦阻力与传热特性进行了试验研究。以动量传递与热量传递的模拟理论为基础,由试验结果的关联得到了动量传递粗糙度函数（R函数）与热量传递粗糙度函数（G函数）的表达式,并与前人工作进行了比较。针对油的Pr随温度变化较大的特性,提出了改进的强化传热性能评价方法,并据此对1号与2号试验管进行了评价。研究结果可用于换热器设计及优化螺旋槽管几何参数。     

Effects of MnO2 and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics

Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ + xmol% MnO₂ lead-free ceramics have been prepared by a conventional sintering method and the effects of MnO₂ and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ lead-free ceramics have been studied. The addition of 0.25 mol% MnO₂ promotes grain growth, improves the ferroelectricity of the ceramics and strengthens ferroelectric tetragonal–ferroelectric orthorhombic phase transition near 40 °C. Because of the coexistence of tetragonal and orthorhombic phases and the combinatory effects of soft and hard doping of Mn ions, the ceramic with x = 0.25 exhibits the optimum piezoelectric properties (d ₃₃ = 306 pC/N and k _p = 42.2 %, respectively). Excess MnO₂ inhibits the grain growth and degrades the ferroelectric and piezoelectric properties of the ceramics. Sintering temperature has an important influence on the microstructure, tetragonal–orthorhombic phase transition near 40 °C, ferroelectric and piezoelectric properties of the ceramics. The increase in sintering temperature leads to large grains and more noticeable tetragonal–orthorhombic phase transition near 40 °C, enhances ferroelectricity and thus improves effectively the piezoelectricity of the ceramics. The Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ ceramic sintered at 1350 °C possesses the optimum piezoelectric constant d ₃₃ value of 373 pC/N.     

无线传感器网络研究进展

无线传感器网络因其巨大的应用前景而受到学术界和工业界越来越广泛的重视.介绍了无线传感器网络的基本概念以及具有应用代表性的研究项目,总结提出了网络协议体系结构框架并简要介绍了各主要研究方向的最新进展,本文还针对最受关注的数据链路层协议、网络层路由协议、协议栈优化、能耗管理以及网络仿真技术等几个研究热点做了比较详细的研究进展综述.     

Study of the electronic structures of oxygen doped in LiBaF3 crystal

The most likely substituting positions of impurity oxygen ions in LiBaF₃ crystals are studied using the general utility lattice program (GULP). The calculated results indicate that the main defect model is [] in the O:LiBaF₃ crystal. The electronic structures of the LiBaF₃ crystal with the defect [] are calculated using the DV-Xα method. It can be concluded from the electronic structures that the LiBaF₃ crystal with the defect [] will exhibit a 217-280 nm absorption band and the impurity oxygen will decrease core-valence luminescence yield.     

发电侧多主体投资低碳综合微网氢储能的演化策略

在低碳经济背景下,为提高向大用户直供能的灵活性,解决多主体在有限理性下共建共享的非对称性行为决策问题,提出多新能源场站联合投资低碳综合微网氢储能的演化行为分析方法。首先,利用异质性新能源场站发电与大用户用能的时空互补特性,提出多主体共享低碳综合微网氢储能的基本框架,使各发电主体形成“自平衡+直供电+余量上网”模式,在增强新能源友好并网能力与供用能灵活性的同时降低投资成本。然后,考虑多主体在参与氢储能共建共享时的非对称行为决策,基于复制者动态方程与演化稳定定理,对多新能源场站在有限理性下的多投资策略进行演化行为分析。最后,以我国西北部新能源汇集区域为算例对发电侧在联合投资中的合作行为进行推演,结果表明政府可通过对间断性发电特征的电站给予适当补助,或细化电价设置来激励异质性新能源场站的联合投资行为,从而促进氢储能的规模化发展;新能源场站则可通过提高装机容量来保证自身定值收益。