耐水脱硫石膏、粉煤灰胶结材的研究

本文较深入地研究了脱硫石膏粉煤灰化学成分、杂质、颗粒特征和激发剂等对脱硫石膏、粉煤灰胶结材性能的影响 研究表明 ,激发剂是影响脱硫石膏、粉煤灰胶结材性能的主要因素 这为脱硫石膏、粉煤灰资源化利用打下良好理论基础 经实际应用表明 ,研究结果与实际情况能很好相符     

正弦稳态扫频信号的产生与输出

介绍用计算机软件产生正弦稳态扫频信号的编程方法。通过对Ｄ／Ａ变换与Ａ／Ｄ采集的同步输出可以获得不同频率量程和设定电压的扫频输出     

一类高阶非线性系统的零解稳定性

由Барбащин公式得到的四阶常系数线性系统的Ляпунов函数出发，通过类比法构造了一类四阶非线性系统的Ляпунов函数，并由此得到了这些系统零解的全局渐近稳定性的充分条件     

Geological constraints on tidal dissipation and dynamical ellipticity of the Earth over the past three million years

The evolution of the Solar System has been shown to be chaotic, which limits our ability to retrace the orbital and precessional motion of the Earth over more than 35-50 Myr (ref. 2). Moreover, the precession, obliquity and insolation parameters can also be influenced by secular variations in the tidal dissipation and dynamical ellipticity of the Earth induced by glacial cyclicity and mantle convection. Here we determine the average values of these dissipative effects over the past three million years. We have computed the optimal fit between an exceptional palaeoclimate record from the eastern Mediterranean Sea and a model of the astronomical and insolation history by testing a number of values for the tidal dissipation and dynamical ellipticity parameters. We find that the combined effects of dynamical ellipticity and tidal dissipation were, on average, significantly lower over the past three million years, compared to their present-day values (determined from artificial satellite data and lunar ranging). This secular variation associated with the Plio-Pleistocene ice load history has caused an average acceleration in the Earth's rotation over the past 3 Myr, which needs to be considered in the construction of astronomical timescales and in research into the stationarity of phase relations in the ocean-climate system through time.