Expert Algorithmic and Imagistic Problem Solving Strategies in Advanced Chemistry

Abstract

Visualization and imagistic reasoning appear central to expert practice in science; however, expert use of these strategies on authentic tasks has not been examined in detail. This study documents how science experts use both algorithms and imagistic reasoning to solve problems. Using protocol analysis, we report expert chemists' preferential use of algorithms for solving spatial problems and imagistic reasoning for deducing spatial transformations. We observed experts employ algorithms to solve the majority of spatial tasks while reserving imagistic strategies to solve a class of tasks that required translating between representations. Strategy used varied widely among experts and tasks.     

基于查表的开环MPM预失真器

提出了一种基于查表的开环记忆多项式模型(MPM,Memory Polynomial Model)预失真器.从MPM预失真器系数估计和执行信号预失真处理两方面加以考虑.首先,利用预失真器和高功率放大器(HPA,High Power Amplifier)传输特性的互补性,由采集到的HPA输入、输出基带数据进行单次最小二乘估计得到MPM预失真器的系数,避免了以往递归结构的收敛性和计算量大等问题.然后,利用MPM预失真器的特点,建立了基于输入信号强度索引的一维向量表,通过查表实现MPM预失真器的幂次累加项,极大地减少了实现预失真器所需的计算量及硬件开销.仿真显示,采用提出的预失真器可以有效补偿HPA对信号的记忆非线性失真,有效带宽内获得了近20 dB的功率改善,也显著改善了系统误码性能.     

太阳电池阵列模拟器计量测试方法研究

对太阳电池阵列模拟器(SAS)的设计原理和技术要求进行了分析,并根据分析结果对太阳电池阵列模拟器计量测试方法进行了研究。     

机载用电设备的供电适应性试验系列标准制定与实施

机载用电设备的供电适应性试验是对各类机载用电设备在各种供电状态下的性能以及用电设备工作对供电系统影响的验证，是保证用电设备（尤其是大功率电子设备）与飞机供电系统相兼容的重要措施和方法。本文阐明了我国机载用电设备的供电适应性试验系列标准的组成和相互关系，着重对供电适应性试验方法标准的定位、框架、结构要素的确定和主要内容进行了分析，并提出实施供电适应性方法标准的建议。     

卫星遥测功率谱分析和调制度测量方法研究

残余载波调制是卫星测控中的常用调制体制。文章从理论上给出了该体制下信号的功率谱密度表达式，得到奇次谐波谱线展宽等结论，并通过仿真和实验进行了验证。利用所得结论讨论了遥测调制度测量方法，提出通过功率谱的2阶边带进行测量可以使结果得到改善。     

Mathematical description of the NaK model for MASTER-2005

The release of NaK droplets has been modeled for the new version of the European Meteoroid and Space Debris Terrestrial Environment Reference model MASTER-2005. Previously published versions of the model have been revised. The parameters of the model are introduced and discussed. NaK droplets consist of eutectic sodium–potassium alloy and have been released during RORSAT reactor core ejections. They contributed to the space debris environment in the centimeter and millimeter size regime. Sixteen nuclear powered RORSATs launched between 1980 and 1988 activated a reactor core ejection system in Sufficiently High Orbits (SHO), mostly between 900 and 950 km altitude. The core ejection caused an opening of the primary coolant circuit. The liquid coolant has been released into space during these core ejections. The outflow is considered as a discrete event for each of the sixteen core ejections in total. The NaK coolant has been forming droplets up to a diameter of 5.5 cm. NaK releases are restricted to a very narrow region near 65° inclination. This paper gives the parameters of the NaK release model as it is implemented in MASTER-2005. The quantitative values of all model parameters including characteristic diameter and uniformity parameter are presented. The ratio of the characteristic droplet size to the orifice diameter is discussed. It is estimated that altogether 128 kg of NaK-78 (8 kg per RORSAT) was released on orbit. Simulation runs show that there are still 45,000 droplets with a total mass of 97 kg in orbit at the reference epoch 1 May 2005, whereas the smallest droplet has a diameter of 5 mm. Results of orbit propagation simulation runs are presented in terms of spatial density.     

国际空间太阳能电站的技术进展

综述了当前国际空间太阳能电站技术的研究进展与发展趋势。重点介绍了空间太阳能电站系统方案新构思“太阳塔”和“太阳盘”的特点；介绍了空间太阳能电站的主要相关技术———无线电能传输技术、太阳能转换技术和空间运输技术等的发展趋势；最后简要介绍了月球电站的进展情况。     

混合三元系超大集

对于三类混合三元系超大集Ti-OLGD（v）（i=1,2,3）,T1-OLGD（v）和T2-OLGD（v）的存在谱已经完全解决了,而对于T3-OLGD（v）的存在性问题,所知结果很少。本文利用代数和组合设计相结合的方法,主要利用有限域的相关知识,对于T3-OLGD（q-1）（q为素数幂）,给出了一种新的构造方法,从而得到了一系列的结果。     

MPPT不调节母线电源系统稳定性分析

提出了一种MPPT不调节母线电源系统拓扑结构,介绍了其控制策略。分别建立了两域控制模式下太阳电池阵源端与负载端稳态分析的等效电路模型,基于小信号等效分析及状态空间方程特征根求解方法,对系统稳定性进行分析,归纳了提高此类电源系统稳定性设计的方法,此研究结果可为MPPT控制技术在未来空间电源系统中应用提供设计参考。     

模块航天器间激光无线能量传输系统方案设想

模块化航天器是未来航天器发展的重要方向,模块航天器之间的能量传输是实现模块化功能应用的关键技术。文章针对模块化航天器系统能量分配需求,对无线激光能量传输技术进行了研究。阐述了无线激光能量传输系统的功能组成,建立了系统框架模型,分析了系统的关键技术,并对系统各组成模块进行了初步设计。在此基础上对激光传能系统进行了试验验证,获得了理想的光电转换效率。文章的研究成果可为我国模块航天器的发展提供技术支持。