Pigeons (Columba livia) associate time intervals with symbols in a touch screen task: Evidence for ordinality but not summation.

The present experiments examined whether pigeons can sum symbols that are associated with various temporal consequences in a touch screen apparatus. Pigeons were trained to discriminate between two visual symbols that were associated with 0, 1, 2, 3, 4, or 5 s either of delay to 4 s of hopper access (delay group) or duration of hopper access (reward group). In Experiment 1, the pigeons in both groups learned to select the symbol associated with the more favorable outcome, and they successfully transferred this discrimination to novel symbol pairs. However, when tested with 2 pairs of symbols associated with different summed durations, they responded on the basis of a simple response rule rather than the sum of the symbol pair. In Experiment 2, the reward group was presented with four symbols at once and was allowed to successively choose one symbol at a time. All pigeons chose the symbols in order from largest to smallest. This indicates that pigeons formed an ordered representation of symbols associated with different time intervals, even though they did not sum the symbols. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evolution of available lysine and furosine contents in milk‐based infant formulas throughout the shelf‐life storage period

The evolution of the Maillard reaction (MR) by measuring the available lysine and furosine (FUR) contents in adapted and follow‐up powdered milk‐based infant formulas over the shelf‐life storage period, at 20 and 37 °C, was studied. Available lysine and FUR contents were determined by fluorimetry and high‐performance liquid chromatography respectively. Statistically significant differences were found between adapted and follow‐up infant formulas with respect to the available lysine and FUR contents. Available lysine contents decreased significantly throughout the storage time, and the contents at 37 °C were lower than at 20 °C. A statistically significant increase in FUR contents was observed during the storage period, with the contents being high at 37 °C than at 20 °C. A simple regression analysis between the available lysine and FUR contents during (a) the first year (b) the second year and (c) the two storage years was applied. The best correlations were obtained during the first year of storage. The results obtained show a clear MR evolution during the storage of infant formulas. Copyright © 2003 Society of Chemical Industry     

四边形单元面积坐标的微分和积分公式

构造四边形单元时，应用面积坐标方法有其优点。文献［１］系统地论述了四边形单元面积坐标理论，本文是文献［１］的续篇，补充论述采用四边形单元面积坐标时的微分和积分公式。采用三角形单元面积坐标时的微分和积分公式是其特殊情况。应用面积坐标方法时，易于得出四边形单元刚度矩阵的积分显式，无需依赖于数值积分，这个优点是采用四边形等参坐标时所不具备的。     

恒定轴压力下Q690高性能钢管抗弯性能的试验研究

为研究国家电网输电塔中高强钢焊接中厚板圆管压弯稳定相关性,考虑长细比30、45和60,径厚比(D0/t)为31.25、50.00和58.33,以壁厚为6,8 mm国产Q690高性能钢板制作了5组15根焊接圆管试件,并对其进行恒定轴压力下的抗弯性能试验。记录各试件加载过程中变形现象,得到了试件的弯矩-轴向变形曲线。根据试验结果分析试件的承载力、失稳破坏模式和破坏状态等力学性能,并采用中国及美国相关行业规范公式对压弯承载力进行验算对比。结果显示:失稳破坏类型主要取决于钢管试件径厚比和长细比,随长细比减小或径厚比增大,构件破坏类型由整体失稳转化为局部失稳;失稳状态关键在于径厚比,随径厚比减小,破坏状态由弹性转化为弹塑性;所有规范设计公式均偏于保守,验证了相关规范压弯设计公式和稳定系数取值用于指导工程设计的可行性和合理性。     

页岩烧结保温砌块砌体受压变形性能研究

介绍了现有砌体受压本构关系,并对其优缺点进行分析;针对29排孔和21排孔两类页岩烧结保温砌块砌体变形性能进行了分析,根据试验结果给出了该砌体受压应力—应变曲线,并提出了该砌体受压本构关系计算式和弹性模量计算式,最后给出了砌体泊松比建议取值。     

FRP加固局部损伤钢压杆的稳定分析

钢结构中存在大量的轴心受力构件,作为承受永久竖向荷载的主要构件,往往是结构加固的重点.采用能量方法,分析各种杆端约束条件下,纤维增强复合材料（FRP）加固局部损伤的轴心受压钢构件在弹性失稳时的弹性屈曲临界力,并建立普遍适用的近似欧拉公式.利用ANSYS通用有限元分析软件分析FRP的厚度对损伤空心圆管临界力的影响并与该公式解析解进行对比.计算结果表明,该公式计算结果可靠,采用纤维增强复合材料加固修复局部损伤的钢结构可以有效恢复其刚度和稳定性.     

基于ANSYS的叶片式液压加载器的有限元分析

简要地阐述了叶片式液压加载器的工作原理,利用三维软件Pro/E建立加载器的简化模型叶片轴与叶片总成,分别导入有限元分析软件ANSYS进行网格划分,对叶片轴与叶片总成进行有限元分析得出等效应力和变形矢量总和,最后对它们进行校核,为叶片式液压加载器的实际应用和后期设计提供了理论依据.     

双检理论研究及合成处理

本文深入探讨了水、陆检波器的接收机制及波场动力学特征,认识到水层鸣震是由下行鬼波(虚反射)和上行微曲多次波组成。水检和陆检对于一次波、鬼波和微屈多次波具有不同的响应特征:对于一次波,双检的响应表现为同向;对于鬼波,双检的响应表现为反向;对于微曲多次波,双检的响应表现为同向。因此,本文通过水检和陆检同时采集的数据叠加去除鬼波;在此基础上,进一步求取海底反射系数,从而消除上行微屈多次波。本文方法在实际OBC资料处理中取得了良好应用效果。     

刚性固定露出式钢柱脚锚栓设计计算公式的拓展研究

本文对我国<钢结构设计手册>中给出的刚性固定露出式钢柱脚锚栓设计方法进行了拓展,推导出了在大偏心受压、大偏心受拉、小偏心受拉三种受力情况下,对称于弯矩作用轴的任意形状底板上的、任意方式布置的锚栓设计的一般公式,以及针对底板为矩形、圆形、圆环形时的具体计算公式,供相关设计人员参考.     

高效抑制斜入射光线Fresnel反射的均匀扩散板设计

针对无导光板LED平板灯具设计中常规扩 散板对斜入射光线透过率低的问题,基于几何光 学和Fresnel公式,设计了一种具有高效抑制斜入射光线Fresnel反射的表面微结构扩散板, 并推导了获得 高光传输效率的三棱柱微结构参数计算公式。采用Solidworks软件进行建模,并结合TraceP ro软件对所设计 的扩散板进行光线追迹仿真,分析了扩散板微结构参数对光传输效率和照明面照度均匀度的 影响。结果表 明,入射表面微结构不等腰三棱柱的尺寸和形状、出射表面半凹球面微透镜直径对斜入射光 线传输效率都 有较大影响;参数优化后的扩散板,在距离出光面 1mm处的照明面上的光传输效率为0.92,照度均匀度为 96.8%,并且不同距离照明面上的照度均匀度均能达到80%以上 。根据理论分析得出的优化参数制作扩散板,得到传输效率为0.91。