Structures on sliding base subject to horizontal and vertical motions

In this paper particular investigation is directed towards the combined effects of horizontal and vertical motions of real earthquakes to structures resting on sliding base. A simplified method is presented to treat the nonlinear effects of time dependent frictional force of the sliding base as a function of the vertical reaction produced by the foundation. As an example, the El Centro 1940 earthquake record is used on a structural model to show the structural responses due to a sliding base with different frictional and stiffness characteristics. The study shows that vertical ground motion does affect both the superstructure response and the base sliding displacement. Nevertheless, the sliding base isolator is shown to be effective for the reduction of seismic response of a superstructure.

Saturation impulses for dynamically loaded structures with finite-deflections

The concept of ''Saturation Impulse'' for rigid, perfectly plastic structures with finite-deflections subjected to dynamic loading was put forward by Zhao, Yu and Fang (1994a). This paper extends the concept of Saturation Impulse to the analysis of structures such as simply supported circular plates, simply supported and fully clamped square plates, and cylindrical shells subjected to rectangular pressure pulses in the medium load range. Both upper and lower bounds of nondimensional saturation impulses are presented.

A Dynamic Model For Ice-Induced Vibration Of Structures

A dynamic model for the ice-induced vibration (IIV) of structures is developed in the present study. Ice properties have been taken into account, such as the discrete failure, the dependence of the crushing strength on the ice velocity, and the randomness of ice failure. The most important prediction of the model is to capture the resonant frequency lock-in, which is analog to that in the vortex-induced vibration. Based on the model, the mechanism of resonant IIV is discussed. It is found that the dependence of the ice crushing strength on the ice velocity plays an important role in the resonant frequency lock-in of IIV. In addition, an intermittent stochastic resonant vibration is simulated from the model. These predictions are supported by the laboratory and field observations reported. The present model is more productive than the previous models of IIV.

稀土离子对钙调蛋白及其靶酶结构与功能的影响

稀土元素由于在农业上的广泛应用已经越来越多地进入到生物体循环中，因此在分子水平上研究它们对生物体功能的影响及其作用机理成为人们迫切需要解决的课题。钙调蛋白（CaM）是广泛存在于生物体内的一种多功能的调节蛋白，调节着至少40余种酶的活性。基于上述原因，本文选取钙调蛋白作为研究对象，系统地比较了不同浓度的钙离子和稀土离子对它的靶酶钙调神经磷酸酶、磷脂酶凡、乳酸脱氢酶活性的影响，并采用荧光光谱、同步荧光光谱、紫外差谱、红外光谱等方法研究了它们对钙调蛋白及其靶酶构象变化的影响。发现稀土离子对钙调蛋白靶酶的活性均表现出"低浓度促进，高浓度抑制"的Hormesis效应，由于靶酶分子结构的差异，其最大激活浓度有所区别，钙调蛋白可以缓解稀土离子对靶酶的抑制作用；发现高浓度的稀土离子与钙调蛋白作用后，可以降低钙调蛋白与靶肤／酶分子的亲合性，并抑制其调节靶酶活性功能的发挥；稀土离子与钙调蛋白作用后，增大其α-螺旋含量，减少价折叠结构，对小肤的二级结构影响较小；二乙三氨五乙酸及其衍生物二乙三胺五乙酸－双二甲酞胺和二乙三胺五乙酸一双（异烟麟）可以作为乳酸脱氢酶的竞争性抑制剂抑制其活性，抑制常数分别为3.37、7.41、8.52μmol几，钙调蛋白也可以缓解它们对脱氢酶的抑制作用；首次制备出一株由稀土离子诱导钙调蛋白构象变化后的单克隆抗体2C3，该抗体可以特异性地识别含稀土的钙调蛋白，与Ca－CaM、La-CaM、Eu-CaM以及Yb-CaM之间的解离常数分别为157、26.8、21.8和64.8 nmol／L，该抗体还能够区分钙调蛋白结合不同浓度稀土离子后的构象状态。

On Combining Morphological Component Analysis and Concentric Morphology Model for Mammographic Mass Detection

Mammographic mass detection is an important task for the early diagnosis of breast cancer. However, it is difficult to distinguish masses from normal regions because of their abundant morphological characteristics and ambiguous margins. To improve the mass detection performance, it is essential to effectively preprocess mammogram to preserve both the intensity distribution and morphological characteristics of regions. In this paper, morphological component analysis is first introduced to decompose a mammogram into a piecewise-smooth component and a texture component. The former is utilized in our detection scheme as it effectively suppresses both structural noises and effects of blood vessels. Then, we propose two novel concentric layer criteria to detect different types of suspicious regions in a mammogram. The combination is evaluated based on the Digital Database for Screening Mammography, where 100 malignant cases and 50 benign cases are utilized. The sensitivity of the proposed scheme is 99% in malignant, 88% in benign, and 95.3% in all types of cases. The results show that the proposed detection scheme achieves satisfactory detection performance and preferable compromises between sensitivity and false positive rates.