基于神经网络的股市预测

本文研究了基于神经网络的股票预测方法．针对目前存在的问题,提出了联合Davidon最小二乘算法及遗传算法来综合训练网络结构和权值的新方法．经对上证指数的模拟预测表明,通过合理地选取参数,可获得满意的预测效果．     

坝面粘贴苯板保护层的拱坝温度荷载研究

寒冷地区拱坝的温度应力比南方大得多,温度荷载的可能大大超过水荷载的影响,为了降低温度荷载,减小拱坝厚度。本文求出了两种不同介质在外界气温作用下的解析解,并针对在拱坝下游面用苯板作为永久保护层,提出了确定温度荷载的设计计算新方法,给出的温度荷载计算图表可供工程设计直接使用。     

G-m界面断裂对灰口铸铁力学行为及性能的影响

用扫描电镜原位观察技术,发现拉伸早期形成的Ｇ－ｍ界面断裂并不是直接连续扩展成主裂纹,而是逐步再生许多界面裂纹,其间基体韧带缩小而形变裂开将界面裂纹连接起来这些过程局限在裂开前主裂纹及其近邻处很窄的微带区内进行在断口或表面裂纹中,Ｇ－ｍ界面断裂占绝大部份,基体韧带的穿晶断裂只占很少基此对灰口铸铁中石墨与性能关系提出了新的解释     

一种压电超声马达的工作原理

定性介绍了压电陶瓷技术研究所研制的一种压电超声马达的工作原理。通过定量建立和解压电定子的振动方程,得出定子驱动端轨迹为椭圆这一推动转子转动的关键,并对转子材料提出一些要求。     

稀土高氯酸盐甘氨酸咪唑三元配合物的制备及表征

在水溶液中,用稀土高氯酸盐ＲＥ（ＣｌＯ４）ｍ·ｎＨ２Ｏ（ＲＥ＝Ｌａ,Ｐｒ,Ｎｄ,Ｓｍ,Ｅｕ,Ｇｄ,Ｔｂ,Ｄｙ,Ｙ）与甘氨酸ＧＬＹ及咪唑Ｉｍ作用,合成了９种新的三元配合物,对这些配合物经过元素分析、化学分析,确定了它们的化学式为：ＲＥ（ＧＬＹ）４（Ｉｍ）（ＣｌＯ４）３·ｎＨ２Ｏ;并且通过红外光谱ＩＲ、紫外光谱ＵＶ,Ｘ－射线衍射分析及溶解性的测定等,进行了表征,发现了一些规律。     

膳食纤维研究的现状与展望

介绍国内外对膳食纤维的研究状况,其中包括膳食纤维的特性、组成结构、对人体的生理功能、现有资源的开发、制取方法以及在食品加工中的应用等．提出进一步开发膳食纤维,重点应解决资源领域的再扩大,即进行制取和改性方法以及膳食纤维的应用范围拓宽的研究．     

褪黑素对持续光照小鼠学习记忆能力的影响

运用Ｙ－迷宫检测小鼠的分辨学习和记忆能力,观察了年龄,每天２４小时连续１个月的持续光照和每日定时注射褪黑素对小鼠分辨学习和记忆能力的影响。结果表明,成年小鼠与青年小鼠相经学习和记忆能力下降;持续光照可引起小鼠学习记忆能力出现不同程度的下降;实验结果提示,褪黑素在维持学习记忆能力中具有重要作用。     

基于分维计算的颗粒粒度分析方法

提出了一种基于分形检测超细颗粒粒度的新方法及实现算法,超细颗粒在一定条件下产生布朗运动,通过光电系统记录的图象可看成是群体颗粒无规则漫游的结果,从而可用分数布朗运动模型去描述,对所获取的超强微粒布朗运动图象进行处理,然后按以上分形模型进行逐点的分维计算,再用统计的方法转换为粒度信息,从而实现粒度测量,文中给出了具体的算法及算例。     

Symmetry perception in an insect

Symmetrical visual patterns have a salient status in human perception, as evinced by their prevalent occurrence in art, and also in animal perception, where they may be an indicator of phenotypic and genotypic quality. Symmetry perception has been demonstrated in humans, birds, dolphins and apes. Here we show that bees trained to discriminate bilaterally symmetrical from non-symmetrical patterns learn the task and transfer it appropriately to novel stimuli, thus demonstrating a capacity to detect and generalize symmetry or asymmetry. We conclude that bees, and possibly flower-visiting insects in general, can acquire a generalized preference towards symmetrical or, alternatively, asymmetrical patterns depending on experience, and that symmetry detection is preformed or can be learned as perceptual category by insects, because it can be extracted as an independent visual pattern feature. Bees show a predisposition for learning and generalized symmetry because, if trained to it, they choose it more frequently, come closer to and hover longer in front of the novel symmetrical stimuli than the bees trained for asymmetry do for the novel asymmetrical stimuli. Thus, even organisms with comparatively small nervous systems can generalize about symmetry, and favour symmetrical over asymmetrical patterns.     

A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean

The seeding of an expanse of surface waters in the equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability.