巨蛎属（Crassostrea）四种牡蛎精子Bindin蛋白海藻糖凝集素结构域（Fucose binding lectin）多样性研究

提取巨蛎属中熊本牡蛎、葡萄牙牡蛎和日本巨牡蛎的基因组DNA,应用PCR技术扩增了三种牡蛎的海藻糖凝集素结构域（Fucose binding lectin,F-lectin）,结合GenBank中长牡蛎海藻糖凝集素结构域的序列利用邻接法对得到的序列进行了系统进化分析,并利用非同义替换率和同义替换率之间的比值分析了巨蛎属四...     

Periodicity in quasar redshifts or selection effects?

Peaks at high redshifts in individual samples of quasars can be explained as due to selection effects. It is concluded that peaks in quasar redshift distribution do not obey any generalformula that can constitute a periodicity, even though individual samples may favour some redshifts of smaller values, viz. z < 1.     

近地小行星探测目标选择

从数以万计的近地小行星(NEAs)中选择探测目标,是一项非常重要的工作.选择小行星时需要考虑的主要问题是:NEAs的轨道参数、自旋周期、大小、科学价值、表面特征以及到达NEAs的时间.本文采用排除法从众多近地小行星中确定候选者,并根据科学目标的要求确定最终探测目标.     

A framework for the evaluation of ground motion selection and modification procedures

This study develops a framework to evaluate ground motion selection and modification (GMSM) procedures. The context is probabilistic seismic demand analysis, where response history analyses of a given structure, using ground motions determined by a GMSM procedure, are performed in order to estimate the seismic demand hazard curve (SDHC) for the structure at a given site. Currently, a GMSM procedure is evaluated in this context by comparing several resulting estimates of the SDHC, each derived from a different definition of the conditioning intensity measure (IM). Using a simple case study, we demonstrate that conclusions from such an approach are not always definitive; therefore, an alternative approach is desirable. In the alternative proposed herein, all estimates of the SDHC from GMSM procedures are compared against a benchmark SDHC, under a common set of ground motion information. This benchmark SDHC is determined by incorporating a prediction model for the seismic demand into the probabilistic seismic hazard analysis calculations. To develop an understanding of why one GMSM procedure may provide more accurate estimates of the SDHC than another procedure, we identify the role of ‘IM sufficiency’ in the relationship between (i) bias in the SDHC estimate and (ii) ‘hazard consistency’ of the corresponding ground motions obtained from a GMSM procedure. Finally, we provide examples of how misleading conclusions may potentially be obtained from erroneous implementations of the proposed framework. Copyright © 2014 John Wiley & Sons, Ltd.     

Intensity measures for probabilistic assessment of non‐structural components acceleration demand

A fundamental issue in the framework of seismic probabilistic risk analysis is the choice of ground motion intensity measures (IMs). Based on the floor response spectrum method, the present contribution focuses on the ability of IMs to predict non‐structural components (NSCs) horizontal acceleration demand. A large panel of IMs is examined and a new IM, namely equipment relative average spectral acceleration (E‐ASA_R), is proposed for the purpose of NSCs acceleration demand prediction. The IMs efficiency and sufficiency comparisons are based on (i) the use of a large dataset of recorded earthquake ground motions; (ii) numerical analyses performed on three‐dimensional numerical models, representing actual structural wall and frame buildings; and (iii) systematic statistical analysis of the results. From the comparative study, the herein introduced E‐ASA_R shows high efficiency with respect to the estimation of maximum floor response spectra ordinates. Such efficiency is particularly remarkable in the case of structural wall buildings. Besides, the sufficiency and the simple formulation allowing the use of existing ground motion prediction models make the E‐ASA_R a promising IMs for seismic probabilistic risk assessment. Copyright © 2015 John Wiley & Sons, Ltd.     

导航卫星非差精密定轨测站选取策略分析

推导了测站分布对定轨精度影响的公式,提出一种兼顾测站数量、观测数据质量以及测站地理分布的测站选取策略。利用IGS和iGMAS全球观测网数据,设计了3种不同的测站分布方案,进行GPS精密定轨实验。结果表明,使用30个全球均匀分布的测站,GPS三维定轨精度能达到6.0 cm左右|使用40个全球均匀分布的测站,GPS三维定轨精度能达到3.5 cm的水平|使用50个全球均匀分布的测站,GPS三维定轨精度能达到2.8 cm以内|超过50个的测站对GPS定轨精度提高基本上没有贡献。     

基于选权拟合法的电离层电子密度层析重构

附加约束的电离层层析算法是解决电离层电子密度反演中不适定问题的主要方法,为避免此类方法中约束权阵的选取不当对电子密度分布重构产生的不良影响,本文将选权拟合法应用到电离层层析成像技术中.该方法特别设计了依据电子密度空间分布特性构造参数权矩阵的方案.新方法有明确的物理意义,挖掘了隐含的信息量,为解决电离层电子密度反演中由于观测数据的不足等因素引起的不适定问题提供了一种新途径,可以得到符合客观实际的结果.数值模拟实验和实测数据的反演结果证实了该算法有效性、可靠性和优越性.     

Evaluation of a recently proposed record selection and scaling procedure for low‐rise to mid‐rise reinforced concrete buildings and its use for probabilistic risk assessment studies

This paper evaluates a recent record selection and scaling procedure of the authors that can determine the probabilistic structural response of buildings behaving either in the elastic or post‐elastic range. This feature marks a significant strength on the procedure as the probabilistic structural response distribution conveys important information on probability‐based damage assessment. The paper presents case studies that show the utilization of the proposed record selection and scaling procedure as a tool for the estimation of damage states and derivation of site‐specific and region‐specific fragility functions. The method can be used to describe exceedance probabilities of damage limits under a certain target hazard level with known annual exceedance rate (via probabilistic seismic hazard assessment). Thus, the resulting fragility models can relate the seismicity of the region (or a site) with the resulting building performance in a more accurate manner. Under this context, this simple and computationally efficient record selection and scaling procedure can be benefitted significantly by probability‐based risk assessment methods that have started to be considered as indispensable for developing robust earthquake loss models. Copyright © 2013 John Wiley & Sons, Ltd.     

Copula models for frequency analysis what can be learned from a Bayesian perspective?

Large spring floods in the Québec region exhibit correlated peakflow, duration and volume. Consequently, traditional univariate hydrological frequency analyses must be complemented by multivariate probabilistic assessment to provide a meaningful design flood level as requested in hydrological engineering (based on return period evaluation of a single quantity of interest). In this paper we study 47 years of a peak/volume dataset for the Romaine River with a parametric copula model. The margins are modeled with a normal or gamma distribution and the dependence is depicted through a parametric family of copulas (Arch 12 or Arch 14). Parameter joint inference and model selection are performed under the Bayesian paradigm. This approach enlightens specific features of interest for hydrological engineering: (i) cross correlation between margin parameters are stronger than expected , (ii) marginal distributions cannot be forgotten in the model selection process and (iii) special attention must be addressed to model validation as far as extreme values are of concern.     

2010年上海世博会选址研究

根据2010年上海世博会对快捷高效的综合交通运输体系、优美的亲水环境、有效的危机管理系统、高标准的防灾体系等运营环境的基本要求,结合该市中心城区高昂的土地置换成本、高强度的交通流量压力、较弱的承灾能力等客观实际条件,文章提出了将世博会选址于上海临港新城的建议,认为这将有利于发挥临港新城的综合交通网络优势,彰显国际性港口城市的会展功能,形成城市化发展的多重社会经济效应,推动上海加快实施海洋开发战略等。