Temporal variation in modal properties of a base-isolated building during an earthquake

Temporal variation of dynamical modal properties of a base-isolated building is investigated using earthquake records in the building. A batch processing least-squares estimation method is applied to segment-wise time-series data. To construct an input-output system, an auto-regressive model with exogenous input （ARX） of second-order including a forgetting coefficient as a weighting coefficient is used for the estimation of modal parameters. The fundamental and second natural frequencies and the damping ratios of the fundamental and second natural modes of the base-isolated building are identified in the time domain. The identified results are consistent with the results obtained from the micro-tremor vibration data, forced-vibration test data and earthquake records in the present base-isolated building in the case of taking into account the amplitude-dependency of the iso- lators and viscous dampers. It is finally pointed out that several factors, e.g., amplitude dependency of the isolator and damper system and special characteristics of the series-type viscous damper system, may be related complicatedly with the temporal variation in modal properties of the above-mentioned system.     

Simulation of top-down crack propagation in asphalt pavements

Top-down crack in asphalt pavements has been reported as a widespread mode of failure.A solid understanding of the mechanisms of crack growth is essential to predict pavement performance in the context of thickness design,as well as in the design and optimization of mixtures.Using the coupled element free Galerkin (EFG) and finite element (FE) method,top-down crack propagation in asphalt pavements is numerically simulated on the basis of fracture mechanics.A parametric study is conducted to isolate the effects of overlay thickness and stiffness,base thickness and stiffness on top-down crack propagation in asphalt pavements.The results show that longitudinal wheel loads are disadvantageous to top-down crack because it increases the compound stress intensity factor (SIF) at the tip of top-down crack and shortens the crack path,and thus the fatigue life descends.The SIF experiences a process "sharply ascending—slowly descending—slowly ascending—sharply ascending again" with the crack propagating.The thicker the overlay or the base,the lower the SIF; the greater the overlay stiffness,the higher the SIF.The crack path is hardly affected by stiffness of the overlay and base.     

部分线性模型的光滑样条推断

运用光滑样条估计部分线性模型中的非参数函数,利用限制最大似然或广义交叉验证(GCV)的方法选择光滑参数,主要考察了部分线性模型的光滑样条估计以及有关非参数函数部分的假设检验.基于光滑参数的选择方法,提出了部分线性模型中的非参数函数是否为多项式函数的假设检验方法,并通过模拟例子研究本文提出的推断效果.     

连词“缘”的语法化及相关问题考察

"缘"是中古时期新兴的一个表因连词,它的语法化经历了一个由表"凭借、依据"义的动词到工具介词再到表因连词的过程。这个语法化之所以能够完成,内部因素和外部因素的共同作用是一个不可或缺的重要条件。而且这种演变完全是在汉语内部完成的,与语言接触无关。     

加强党的建设促进新建本科高校内涵式发展——以辽宁科技学院四年发展为例

以改革创新精神加强和改进高校党建工作是高校改革发展的重要政治任务和时代课题。新建本科院校面临着自身发展建设中的特殊性问题及外延发展与提升内涵并重的多重压力,因此,学校的党建工作也面临着重要、艰巨而紧迫的任务。文章以辽宁科技学院为例,就如何以党建促进学校内涵式发展,推进学校教育教学改革紧跟经济社会和高等教育飞速发展和快速变化的形势要求,探索并提出了通过开拓创新党建工作解决新建本科院校生存发展问题的有效途径。     

JALIS专题数据库的调查分析与对策思考

专题数据库的建设是JALIS重点建设的三类资源之一。通过对JALIS三期专题数据库的建设情况调查可以得出结论:JALIS专题数据库建设具有主题丰富、参与面广、多个建库平台并存等特点,但也存在建设能力参差不齐、数据量偏少、数据库规模小、数据更新维护滞后等问题,应采取协作策略、推广策略与服务策略等相关策略加以解决。     

“F27企业经济”类目存在的问题及修订措施

经济学科的发展致使《中国图书馆分类法》(第4版)企业经济类目存在如下问题:有关战略管理、人本管理、知识管理和创业的文献无处可归;行政管理类级设置不合理;各种企业经济分类混乱;一些类名不规范。其修订方法为:单独列类;提高行政管理类级;调整企业经济分类;修改过时类名。     

移动边缘计算中的在线任务卸载方法

为减少移动边缘计算(mobile edge computing,MEC)网络中移动用户的长期任务开销,利用强化学习的马尔科夫决策过程,将用户的移动性与系统的动态信息建模为随机优化问题.依据系统信息的状态,将问题分为系统信息已知、系统信息未知2种情况.在系统信息已知时,提供了问题的最优解;系统信息未知时,基于在线学习提出...     

Human cancer genetics

Cancer is a genetic disorder.Although heredi-tary cancers account for only a small fraction of all tumors,most cancers are caused by a variable mix of heredity and environment that leads to accumulations of genetic alterations and then uncontrolled cell pro-liferations(Kops et al.,2005).In addition,genetic alteration is one of the a few most important bio-logical factors that determine the diagnosis and prognosis of different cancers and dictate the treat-ment strategies for cancer patients.Fu…     

Joint effects of microwave and chromium trioxide on root tip cells of Vicia faba

The mutagemc effects of microwave and chromium trioxide （CrO3） on Vicia faba root tip were studied. Micronucleus assay and chromosomal aberration assay were used to determine the mitotic index, the micronucleus frequency and chromosomal aberration frequency of Vicia faba root tip cells induced by microwave and CrO3. The results showed that the micronucleus frequency decreased, and that the mitotic index and chromosomal aberration frequency showed linear dose responses to CrO3, in treatment of microwave for 5 s. In microwave of 25 s, the mitotic index decreased, the micronucleus frequency and chromosomal aberration frequency increased with increase of CrO3 concentration. We concluded that microwave and CrO3 had antagonistic effect on the mitotic index of Vicia faba root tip cells, but had synergetic effect on micronucleus frequency and chromosomal aberration frequency of Viciafaba root tip cells.