基于现有动态口令身份认证技术的分析与改进

身份认证对于保证信息只被合法授权用户获取和访问起着重要作用，因而建立强有力的身份认证机制成为信息安全的关键之一。以现有动态口令身份认证主流技术为参照，提出了一种动态口令同步认证方法，以实现动态口令安全性、有效性与同步程度、验证效率之间的最优化配置。     

长江三峡及邻区板内中强地震的孕震动力学分析

本文在研究长江三峡及邻区地壳─上地幔结构和现今地壳重力场基础上，分析了该区板内中强地震的孕震动力学过程，探讨了整体上相对稳定的长江三峡及邻区孕育和发生中强地震的动力学机制，并提出了该区板内中强地震预测的动力学标志。     

Study on methods of land use dynamic monitoring at county level

Remote sensing technique has played an important role in land use dynamic monitoring, but as for the land use dynamic monitoring at county level, traditional remote sensing methods such as satellite imagery visual interpretation and computer classification can not meet its demand for accuracy. The result of 1: 10 000 land use investigation map has high accuracy, but this method can not be used to dynamically monitor the land use because of its big expenses, long period and difficulty in updating data. In this paper, the characteristics of physiognomy, climate and the status of land use in Dehui County are taken into consideration and a set of method, which takes use of 3S techniques and applies to Northeast China Plain, is come up with. When the land use type of a land parcel changed as a whole, the date updating can be make by changing its land type ID in the attribute table in a GIS. When the land use type of an irregular area changed, GPS receivers are used to position its border. This set of method is characteristic of high accuracy and low expenses. It gets the information of land use change timely and can be used to dynamically monitor the land use. Foundation item: Under the auspices of the key project of the National Ninth Five-year Plan (96-B02-01-07). Biography: LI Lin-yi (1968 —), female, a native of Jilin, Ph. D. candidate of Changchun Institute of Geography, the Chinese Academy of Sciences. Her research interest includes land use change monitoring and crop yield estimation using “3S” techniques.     

正确测定望远镜光能集中度的方法

正确测定望远镜光能集中度的方法苏定强（中国科学院南京天文仪器研制中心，南京２１００４２）主题词天文光学－望远镜－光学检验天文望远镜广泛采用的象质判据是光能集中度，即一定比例的光能量集中在多大的圆中。例如，七十年代的优秀望远镜光能集中度的标准是８０％的...     

我国天文气候特点及潜在（光学／红外）优良台址探讨

收集了我国１９７８─１９８６年和１９９０年，共１０年时间的１９２个地面气象站每天四次总云量的观测资料，分别计算了北京时间０８ｈ，０２ｈ和０８ｈ以及２０ｈ，０２ｈ和０８ｈ的无云概率。分析结果表明：我国所处的天文气候条件的大环境并非是世界上最好的，但在国内相对较好的区域里，精心挑选出受局部地形影响形成的较好台址还是有可能的。     

A bimodal four‐parameter lognormal linear model of soil water repellency persistence

Soil water repellency may be characterized in terms of the delayed infiltration time of a water droplet resting on the soil surface, which is, water drop penetration time (WDPT), or repellency persistence. Such repellency persistence varies nonlinearly with soil water content (θ_g), although no models have been proposed to reproduce the variation of WDPT with θ_g in soils. Dynamic factor analysis (DFA) is used to identify two common patterns of unexplained variability in a scattered dataset of WDPT versus θ_g measurements. A four‐parameter lognormal distribution was fitted to both common patterns obtained by DFA, and these were combined additively in a weighted multiple linear bimodal model. We show how such an empirical model is capable of reproducing a large variety of WDPT versus θ_g curve shapes (N = 80) both within a wide range of measured WDPTs (0–17 000 s) and for samples with organic matter content ranging from 21·7 to 80·6 g (100 g)^?1. Copyright © 2009 John Wiley & Sons, Ltd.     

桩-桩水平振动动力相互作用研究

在采用动力Winkler地基模型并考虑了被动桩与桩周土体相互作用的基础上,运用传递矩阵法求解出层状地基中的群桩水平振动桩-桩动力相互作用因子。与严格解（Kaynia和Kausel,1982年）进行对比,验证了方法的有效性。研究了各因素如桩长、桩底约束、桩间角度以及地基土对桩-桩动力相互作用因子的影响,并提出了＂影响桩长＂的概念。     

基于GIS技术的河流污染动态模拟系统

本文论述了稳态均匀流场中的一维河流水质扩散模型,并在此模型的基础上,基于GIS二次开发技术开发了河流污染动态模拟系统。该系统以乐山市涌斯江支流段的地理底图及基本数据为例,实现了对河流污染情况的动态模拟。通过对该系统的一系列操作,可以对河段任意位置污染物浓度进行自动查询和修改,从而为河流水质污染的监测和管理提供可视化参考依据。     

动态灰色模型在变形预测中的应用

本文在引入序列算子成功构造灰色序列的基础上,详细讨论了灰色预测模型的基本内容和两种动态灰色预测模型的实现,并成功将其应用于广州地铁变形监测的数据预报。实践及理论证明,新陈代谢灰色预测模型由于实时加入系统的最新信息,提高灰区间的白度,预测精度最高;灰数递补模型通过引入灰数,一定程度上也提高了预测的精度。新陈代谢灰色预测模型实践证明预测精度可达到一级。     

覆水砂土场地中桥梁群桩基础地震响应离心试验研究

为探究覆水饱和砂土场地中土-群桩基础-桥梁结构体系动力相互作用规律,自主设计并制作了直（斜）群桩基础-桥梁结构物理相似模型,开展了不同地震动强度和不同特性地震波输入下的离心机振动台试验,分析了群桩基础-桥梁结构动力特性指标,探究了覆水饱和砂土地基超孔隙水压力发展规律和桩-土相互作用动力响应特性。研究结果表明：覆水的存在对地基土-桥梁结构体系的基本周期和阻尼影响很小,但会导致直群桩基础桥梁结构的振动幅值增加20%,而斜群桩基础桥梁结构的振动幅值降低10%;斜群桩基础模型阻尼比是直群桩基础模型的2倍。上覆水导致饱和砂土地基由受低频振动液化深度更大变为受高频振动地基液化深度更大,同时导致小震作用下促进超孔隙水压力发展,而大震作用下则反之。上覆水会增大桥梁上部结构的动力响应和桩身弯矩。上述研究结果可为覆水场地中桥梁工程抗震设计提供关键参考依据。