科研管理项目管理系统设计与开发

信息化时代推动了我国科研水平飞速增长,为各行业、各领域提供先进的技术与设备支持,以此提升我国整体的GDP水平.文章认为在提升科研水平的过程中,科研项目管理系统起到举足轻重的作用,为科研活动的规范性、合理性与可行性提供了参考标准.     

多孔纳米SiO_2微粉的制备与表征

多孔状纳米SiO2 微粉的制备是以水玻璃和盐酸为原料 ,添加适宜的稳定剂 (非离子表面活性剂 )在适宜的pH值和温度下沉淀合成。要得到性能优良的SiO2 纳米微粉 ,最佳工艺的研究尤其重要。用BDL B型电位仪、BET、EPMA 电子探针及DTA TGA等手段对其性能进行了表征 ,结果表明 ,制得的SiO2 超细微粉 ,颗粒呈多孔状 ,具有巨大的比表面积 ,高达 10 0 0m2 /g以上 ,孔径为 2 5 左右。粒度分布均匀 ,粒度可达纳米级 ,这种粉末具有特殊的性能     

Influences of mullite fibers on mechanical and thermal properties of silica-based ceramic cores

Mullite fibers composite silica-based ceramic cores were successfully prepared by injection molding. The effects of mullite fibers on the mechanical and thermal properties of ceramic cores were investigated. The results indicated that the linear shrinkage was significantly decreased and the porosity was gradually increased with the increase of mullite fibers. In addition, the flexural strength for the room temperature and the simulated casting temperature of 1500°C was increased to a maximum value when the content of mullite fibers was about 1 wt.%, and then decreased with the increase of mullite fibers. The mullite fibers of 1 wt.% presented excellent mechanical properties with a linear shrinkage of .65%, a porosity of 6.96%, and a flexural strength of 17 MPa at room temperature and 34.83 MPa at the simulated casting temperature of 1500°C. Besides, the change in microstructure and properties in various contents of mullite fibers were analyzed.     

Two New Quinochalcone C-Glycosides from the Florets of Carthamus tinctorius

Two new quinochalcone C-glycosides, named hydroxysafflor yellow B (1) and hydroxysafflor yellow C (2), along with two known quinochalcone C-glycosides, safflomin C (3) and saffloquinoside C (4), and one known flavanone, (2R)-4'',5-dihydroxyl-6,7-di-O-β-d-glucopyranosyl flavanone (5), were isolated from the florets of Carthamus tinctorius. Their structures were determined by extensive spectroscopic (UV, IR, HR-ESI-MS, 1D and 2D NMR) analyses. In addition, these quinochalcone C-glycosides together with hydroxysafflor yellow A and anhydrosafflor yellow B were evaluated for their anti-oxidative effects against H₂O₂-induced cytotoxicity in cultured H9c2 cells. Among them, compound 2 exhibited significant anti-oxidative effects.     

基于空间句法的现代住区空间结构研究

现代住区在长期的发展过程中已凸显的诸多问题,＂活力不足＂、＂人情冷漠＂等现实困顿亟需解决。住区空间是人性化的空间,空间的相互关系—构型决定了人在住区中的认知和行为。文章通过对长沙现代住区的实地调研分析,运用＂空间句法＂研究方法,建立拓扑结构分析模型,以此模型分析住区结构,从整合度、连接度和平均深度三个方面探讨住区空间结构塑造人的运动和共同在场的方式,分析整体的空间通达性和关联性等,从而为充满活力的现代住区的设计提供思路。     

电力市场中MCP和PAB机制的Swarm仿真分析

竞价机制的设计一直是电力市场设计的难点。采用Swarm仿真的研究方法对两种竞价机制的均衡过程进行了比较分析。仿真发现,在市场出清价MCP（Market clearing price）和按报价支付PAB（Pay-as-Bid）机制下,在发电商博弈过程中,PAB机制中出清电价低于MCP机制;在发电商博弈达到市场均衡后,MAC机制中出清电价低于PAB机制;在PAB机制中,每个发电商成交电量和成交价格的波动幅度要小于MCP机制。在竞争博弈过程中发电商的无意识共谋行为也是两种竞价机制中存在市场力的原因之一。     

一种适用于复合制导的中末制导弹道交接班方法

导弹武器系统的发展趋势是由单一制导模式向复合制导过渡,而中末制导的可靠交接班是复合制导的关键步骤。针对复合制导中的中末制导弹道交接班问题,在分析中末制导弹道平滑过渡约束条件的基础上,提出了一种简单有效的线性中末制导交接班算子,详细计算了平滑算子的加权系数。通过直升机载空地导弹的中末制导弹道交接班的仿真试验,验证所提方法的可行性。试验结果表明,在较小中末制导律差异条件下,所提算子可实现弹道的平滑过渡和良好衔接。     

基于信道估计的SC-FDMA自适应传输方案

由于SC-FDMA的峰均功率比（PAPR）比OFDMA低,因而被应用于3GPP LTE上行链路。论文分析了SC-FDMA传输系统的数学模型,介绍了基于导频的SC-FDMA系统最小二乘（LS）和线性最小均方误差（LMMSE）信道估计算法。在比较该系统集中式和分布式两种子载波映射方式在高低速不同移动环境下传输性能的基础上,提出了一种基于信道估计的SC-FDMA系统自适应传输方案。经仿真证实该方案比单纯采用一种子载波映射的方法性能更加优越,在相同的误码率情况下,能够节省大概3dB左右的信噪比。     

调度员培训仿真器中三相不对称系统的稳态仿真

针对调度员培训仿真器(DTS)的特点,提出了一个在以单相仿真为主的DTS中嵌入三相不对称系统稳态仿真的方法,包括潮流计算和故障分析。该方法基于相分量模型,除对变压器和线路采用详细模型外,还能够考虑多项式负荷。算法在不收敛情况下以误差最小解为计算结果,提高了DTS的鲁棒性。以消弧线圈接地电网的仿真为例说明了该方法的有效性和在DTS中的重要作用,并揭示出负荷特性对消弧线圈运行整定有重要影响。     

Swelling behaviors of superabsorbent chitin/carboxymethylcellulose hydrogels

Novel superabsorbent chitin/carboxymethylcellulose (CMC) hydrogels were successfully prepared from mixture of CMC and chitin solution dissolved in 8 wt% NaOH/4 wt% urea aqueous system at low temperature by crosslinking with epichlorohydrin. The morphology and structure of the resultant composite hydrogels were investigated by scanning electron microscope, thermogravimetry, and Fourier transform infrared spectroscopy. The results indicated that the stiff chains of chitin are as a strong backbone in the hydrogel to support the pore wall, whereas the CMC contributed to water absorption. The maximum swelling ratio in water reached an exciting level of 1300 as the hydrogels still kept an intact appearance. Moreover, the hydrogels exhibited smart swelling and shrinking behaviors in NaCl and CaCl₂ aqueous solution, showing salt-responsive adsorption behaviors in different media. This work provided a “green” pathway to prepare chitin-based superabsorbent hydrogels, which would be potential for the application in the biodegradable water-absorbent material field.