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701.
Alejandra Barrera Gonzalo Tejera Martin Llofriu Alfredo Weitzenfeld 《Spatial Cognition & Computation》2013,13(1):27-59
In his landmark article, Richard Morris (1981) introduced a set of rat experiments intended “to demonstrate that rats can rapidly learn to locate an object that they can never see, hear, or smell provided it remains in a fixed spatial location relative to distal room cues” (p. 239). These experimental studies have greatly impacted our understanding of rat spatial cognition. In this article, we address a spatial cognition model primarily based on hippocampus place cell computation where we extend the prior Barrera–Weitzenfeld model (2008) intended to allow navigation in mazes containing corridors. The current work extends beyond the limitations of corridors to enable navigation in open arenas where a rat may move in any direction at any time. The extended work reproduces Morris's rat experiments through virtual rats that search for a hidden platform using visual cues in a circular open maze analogous to the Morris water maze experiments. We show results with virtual rats comparing them to Morris's original studies with rats. 相似文献
702.
韩星 《西安航空技术高等专科学校学报》2003,21(4):44-46,53
本文是针对张荣明先生《儒教研究的里程碑》一文而作,是针对张先生所涉及到的相关问题而言,不妥之处,敬请各方批评指正。 相似文献
703.
704.
基于迭代学习的PID控制器研究 总被引:6,自引:0,他引:6
将目前对u(t)的记忆与修正改成对期望控制ud(t)的记忆与修正,提出两种新的拟合控制系统的PID控制器参数的方法。这两种方法实现的PID控制器较常规的PID控制器结构简单,作用于系统可获得较佳的动态特性和较强的鲁棒性。研究目的是为迭代学习控制理论在设计性能优良的控制器方面扩大应用领域。 相似文献
705.
Peter H. Schultz Carolyn M. Ernst Jennifer L. B. Anderson 《Space Science Reviews》2005,117(1-2):207-239
The NASA Discovery Deep Impact mission involves a unique experiment designed to excavate pristine materials from below the
surface of comet. In July 2005, the Deep Impact (DI) spacecraft, will release a 360 kg probe that will collide with comet
9P/Tempel 1. This collision will excavate pristine materials from depth and produce a crater whose size and appearance will
provide fundamental insights into the nature and physical properties of the upper 20 to 40 m. Laboratory impact experiments
performed at the NASA Ames Vertical Gun Range at NASA Ames Research Center were designed to assess the range of possible outcomes
for a wide range of target types and impact angles. Although all experiments were performed under terrestrial gravity, key
scaling relations and processes allow first-order extrapolations to Tempel 1. If gravity-scaling relations apply (weakly bonded
particulate near-surface), the DI impact could create a crater 70 m to 140 m in diameter, depending on the scaling relation
applied. Smaller than expected craters can be attributed either to the effect of strength limiting crater growth or to collapse
of an unstable (deep) transient crater as a result of very high porosity and compressibility. Larger then expected craters
could indicate unusually low density (< 0.3 g cm−3) or backpressures from expanding vapor. Consequently, final crater size or depth may not uniquely establish the physical
nature of the upper 20 m of the comet. But the observed ejecta curtain angles and crater morphology will help resolve this
ambiguity. Moreover, the intensity and decay of the impact “flash” as observed from Earth, space probes, or the accompanying
DI flyby instruments should provide critical data that will further resolve ambiguities. 相似文献
706.
采用实例推理和遗传算法相结合的方法,研究了航空机械零部件失效模式识别的问题。对用于识别的失效属性的选择、检索相似度计算、训练用遗传算法的适应度函数设计以及训练策略的影响进行了较为详细的描述。应用测试表明,对包含分布均衡的3种模式的情况取得了高于74.67%的识别率,所获得的最佳权值向量对另外2种模式具有很好的识别精度(大于73.3%),对混合多模式情况也具有较好的推广能力。验证了该方法对航空零部件失效模式的识别是可行的。 相似文献
707.
708.
基于神经网络在线建模的非线性动态系统中传感器故障检测方法 总被引:3,自引:1,他引:3
本文提出一种基于神经网络在线建模的动态非线性系统中传感器故障检测方法,它首先利用神经网络在线建立动态非线性系统的超前一步预测模型,然后利用神经网络对传感器的预测输出和传感器实际输出之差与一预定阈值比较以检测传感器故障。本文的优点是可以检测多个传感器故障,同时由于采用在线学习方式,非常适于航天器自主系统传感器故障检测的需要。此外,故障检测阈值的选取也比较简单。为了验证本文方法,仿真了一控制系统中同时发生漂移故障的两个传感器故障检测过程。结果表明,方法十分有效。 相似文献
709.
任爱珍 《华北航天工业学院学报》2007,(3)
"语言习得"与"语言学习"是外语教学理论研究中的两个重要概念,克拉申认为只有"习得"来的语言才能成为流利的口头表达,而"学习"只能起"监查"作用。在"学习"的条件下,通过营造人为目的语习得环境,以用为本,立足实践,学习者同样可以达到习得外语的目标。 相似文献
710.
Qi Wang Holly A. Taylor Tad T. Brunyé Keith B. Maddox 《Spatial Cognition & Computation》2014,14(1):58-89
People use spatial and nonspatial information to structure memory for an environment. Two experiments explored interactions between spatial and social categories on map memory when mediated by retrieval (Experiment 1) and encoding (Experiment 2) demands. Participants studied a map depicting business locations (including proprietors' race). In Experiment 1, participants completed two memory tasks, one globally focused and the other locally focused. The global task compressed, while the local task expanded, within-category similarity. Furthermore, processing styles carried over to the subsequent task. Experiment 2 emphasized either the spatial or social category during encoding, which increased that category's weighting in memory. These results extend the work of Maddox, Rapp, Brion, and Taylor, suggesting that retrieval and encoding demands can shift how these categories affect spatial memory. 相似文献