Measuring place-based accessibility under travel time uncertainty

Travel time uncertainty has significant impacts on individual activity-travel scheduling, but at present these impacts have not been considered in most accessibility studies. In this paper, an accessibility evaluation framework is proposed for urban areas with uncertain travel times. A reliable space-time service region (RSTR) model is introduced to represent the space-time service region of a facility under travel time uncertainty. Based on the RSTR model, four reliable place-based accessibility measures are proposed to evaluate accessibility to urban services by incorporating the effects of travel time reliability. To demonstrate the applicability of the proposed framework, a case study using large-scale taxi tracking data is carried out. The results of the case study indicate that the proposed accessibility measures can evaluate large-scale place-based accessibility well in urban areas with uncertain travel times. Conventional place-based accessibility indicators ignoring travel time reliability can significantly overestimate the accessibility to urban services.     

日长的十年尺度变化研究

用高精度的日长资料和由人卫激光测距（ＳＬＲ） 解算出的地球引力场系数Ｊ２ 的变化序列ΔＪ２ ,证明地球各圈层的物质迁移对日长１０ 年尺度变化贡献仅占日长１０ 年尺度变化的４ ％ ,可以忽略;认为１０ 年尺度变化主要来源于地球各圈层的内力矩或相对角动量部分,其优点是可以不顾及地球各圈层物质迁移复杂的物理机制     

用灰色系统理论分析南京东郊岩溶水源地地下水动态

以灰色关联分析的方法对地下水动态进行研究是可行的,能为水源地地下水动态的控制指出方向,为地下水资源的合理开发、利用提供科学依据。      

山东乳山海滩岩及其重要科学意义

乳山海滩岩,经过室内对微体化石、大化石和沉积岩石学研究,查明该岩体具有典型的海滩岩特征:含有两种文石胶结物、滨海相微体古生物和热带大化石。该岩体形成在全新世最佳气侯期,至少有3次成岩期,对研究古环境变化规律具有重要的科学意义。     

鲈鱼的形态和生态特征及养殖结果

本文根据现有文献资料和笔者的研究结果,比较了不同产地,不同种群鲈鱼的形态、生态特征和各地的养殖结果,分析了产生不同结果的重要原因,提出了充分利用不同种类及产地的鲈鱼为人类造福。     

基于二维模式的PDM与MRPⅡ无缝衔接可行性分析

ＣＩＭＳ工程的重要思想是将企业全部生产经营活动视为有机整体,可以集成与优化。但是,目前我国ＣＩＭＳ工程中ＰＤＭ与ＭＲＰⅡ分系统并未真正实现紧密结合与集成,甚至是彼此分离,无直接衔接。在实践经验的基础上,作者探讨了基于二维模式的ＰＤＭ与ＭＲＰⅡ紧密衔接可行性,提出了实现这一衔接的初步设想     

不动产地籍和产权登记信息系统

介绍了一种涵盖地籍管理过程且在实施过程中简单易行而有效的信息系统,为土地资源的合理开发利用和地籍信息的动态管理了新的途径。     

暴雨过程的中尺度分析

利用１９９８年６月１３日００时－１４日１４时地降水量,地面风场,高空雷达回波资料,被步分析了中尺度过程的演变特征,同中尺度系统是造成暴雨的直接原因并统计出物量,中低压环流活动与暴雨的对应关系。在大尺度环流形势下,中尺度辐合线和地形作用为局地大暴雨提供了有利条件。     

A dynamic 2DH flocculation model for coastal domains

Ocean Dynamics - A dynamic two-dimensional depth-averaged (2DH) parameterization for flocculation of cohesive sediments is proposed based on the kinetic model by Winterwerp (J Hydraul Res...     

美国罗德河流域地下水中铝形成动力学

In the Rhode River estuarine/watershed area, increased acidity of precipitation from atmospheric acidic deposition has deleterious effects on the freshwater ecosystems. One of the characteristics of an acidic watershed is the mobilization of aluminum from soils to aquatic environment. Increased concentrations of aluminum in surface waters are toxic to living organisms. Detection of long-term changes of acidity and elevated Al concentrations in surface and soil waters is a central issue. In this present paper, the dynamics ofAl speciation in the shallow ground waters from Rhode River watershed 110 (la) were investigated. This research provides a unique, regional analysis of important controls on the transport of Al speciation through the rural watershed of the Chesapeake Bay.