河流与古代开封城

古代开封城的历史就是一部城市与河流的关系史,开封的兴衰都与河流有着十分密切的关系。古代开封城的发展,既得益于河流,又受害于河流。一言以蔽之,河流兴则开封兴,河流衰则开封衰。     

民国时期藏密在汉地的传播

民国时期中国佛教复兴的一个突出特点是藏传密教在汉地得到了广泛的传播。此次藏密的内陆传承虽然没有元、明、清时代帝王统治的大力护持,但传播的范围却更广,社会影响更显著。文章从清末民初藏密在汉地传播的时代背景、民国时期藏密在汉地传播的特点及其社会影响三个方面展开论述,以期对民国时期藏密在汉地的传播有一个全面客观的认识     

内陆地区县域涉外劳务输出问题思考

劳务输出是对外经济合作的一种重要形式。我国内地县域劳动力丰富,人多地少,存在着大量待业人员。因此,积极开展涉外劳务输出,在增加劳动者收入,加快内地县域经济发展等方面发挥着巨大作用。但是,在涉外劳务合作过程中,涉外劳务纠纷也越来越多,暴露出体制和法律还需完善,合作领域有待拓宽等问题。本文全面分析了内地县域涉外劳务输出的作用及其存在的问题,并提出了对策建议。     

Using a piecewise linear bottom to fit the bed variation in a laterally averaged,z‐co‐ordinate hydrodynamic model

In developing a 3D or laterally averaged 2D model for free‐surface flows using the finite difference method, the water depth is generally discretized either with the z‐co‐ordinate (z‐levels) or a transformed co‐ordinate (e.g. the so‐called σ‐co‐ordinate or σ‐levels). In a z‐level model, the water depth is discretized without any transformation, while in a σ‐level model, the water depth is discretized after a so‐called σ‐transformation that converts the water column to a unit, so that the free surface will be 0 (or 1) and the bottom will be ‐1 (or 0) in the stretched co‐ordinate system. Both discretization methods have their own advantages and drawbacks. It is generally not conclusive that one discretization method always works better than the other. The biggest problem for the z‐level model normally stems from the fact that it cannot fit the topography properly, while a σ‐level model does not have this kind of a topography‐fitting problem. To solve the topography‐fitting problem in a laterally averaged, 2D model using z‐levels, a piecewise linear bottom is proposed in this paper. Since the resulting computational cells are not necessarily rectangular looking at the x–z plane, flux‐based finite difference equations are used in the model to solve the governing equations. In addition to the piecewise linear bottom, the model can also be run with full cells or partial cells (both full cell and partial cell options yield a staircase bottom that does not fit the real bottom topography). Two frictionless wave cases were chosen to evaluate the responses of the model to different treatments of the topography. One wave case is a boundary value problem, while the other is an initial value problem. To verify that the piecewise linear bottom does not cause increased diffusions for areas with steep bottom slopes, a barotropic case in a symmetric triangular basin was tested. The model was also applied to a real estuary using various topography treatments. The model results demonstrate that fitting the topography is important for the initial value problem. For the boundary value problem, topography‐fitting may not be very critical if the vertical spacing is appropriate. Copyright © 2004 John Wiley & Sons, Ltd.     

基于GPRS的内河船舶油耗监测装置研制

为实现内河船舶的节能减排,提高能耗统计监测水平,改进数据采集和生产模式,研制了一种基于电容测量和GPRS相结合的油耗测量装置。对用于船舶的电容式传感器进行了结构设计,并搭建了传感器、GPRS通信模块以及微处理器LM3S1968为核心的检测处理系统,利用软件抗干扰和温度补偿技术对油量信号进行处理,实现对内河船舶耗油量的远程实时监测。实船测试结果表明,装置测量油耗量能较好地反映实际用油量,实现了监测模式的智能化,为内河船舶能耗统计工作带来便捷性、可靠性。     

基于智能手机和RFID的内河航运动态监管与信息服务系统研究

近年来,我国的内河航运得到了长足发展,其运能大、占地少、能耗低、污染小的独特优势和带动经济社会发展的作用逐步凸显。然而,由于航道分布广泛、错综复杂且通行船舶大小各异,我国的内河航运很难实现对船舶的全面动态监管,不能提供优质的信息服务。随着计算机技术和电子技术的不断发展,GPS、AIS、RFID等技术在内河航运监管与服务系统也逐渐出现,此类技术的应用在一定程度上实现了船舶的动态监管或信息服务。针对现有技术因为岸基建设成本或终端成本高而无法实现推广的状况,将充分利用智能手机定位功能和RFID的身份识别功能,同时结合手机通信网络,提出一种基于智能手机和RFID的内河航运管理与服务系统。该系统借助于现有网络运营商的手机通信网络,只需要增加一个RFID标签和在智能手机上安装一个第三方软件便可实现对船舶的全面动态监管,并能提供丰富的信息服务。极大降低了内河航运监管与服务系统的建设成本,具有较强地实际推广意义。     

内陆中心城市产业转型与经济增长实证研究——以郑州市为例

以郑州市为例,分析了内陆区域中心城市产业转型的特点及其与经济增长速度和质量的关系.发现自改革开放以来,郑州三次产业转型速度虽有周期性波动,但总体上在加快.2000年以来,郑州市工业表现出高加工度化、重工业化特点,但超前发展部门的数量有缩减趋势;服务业中的房地产业、金融业、教育等超前发展.与上海、武汉相比,目前郑州工业与服务业升级的任务还较艰巨.虽然三次产业转型对郑州经济增长速度并无显著的促进作用,但对经济增长质量却有明显的影响,而郑州三次产业内部转型对期经济增长速度与质量均有明显的促进作用.     

Integral transforms for three-dimensional steady turbulent dispersion in rivers and channels

A three-dimensional steady-state mathematical model is considered for predicting the fate of dissolved contaminants in rivers and channels under turbulent flow conditions. The model allows for variable velocity fields and non-uniform turbulent diffusivities within channels of rectangular cross sections. Making use of the Generalized Integral Transform Technique (GITT), a hybrid numerical–analytical solution for the concentration fields is then obtained. The solution convergence behavior is investigated and the criterion for reordering the terms in the infinite series is discussed, with the aim of reducing the computational effort associated with the multiple eigenfunction expansions. A test case is presented to illustrate the proposed approach.     

吉林市滨水景观建设探讨

自然河流在城市发展和城市景观建设中具有重要的价值,而河流滨水景观的建设一直是国内外关注的课题.国外在河流滨水地带的景观建设过程中即有失败亦有成功的范例,而我国正处于起步和摸索阶段.以吉林市为例分析了城市河流——松花江的景观特色和滨水景观建设现状,本着人与自然和谐共生的理念,指出其景观建设中存在的问题并对此提出了合理的建议.     

MODIS／Terra遥感雪盖数据在青藏高原河源区的应用

基于2000-2009年MODIS/Terra积雪数据产品,分析我国青藏高原主要河源区雪盖的空间分布和季节变化.结果表明:五江源的积雪在空间上主要集中于雅鲁藏布江河谷、念青唐古拉山及横断山南部等地区,而北部积雪相对偏少;降雪主要集中于春冬季节,且雪盖变化呈现双峰形特点,峰值主要集中在2月和11月.不同季节雪盖表现出一定的趋势变化,春季雅鲁藏布江源区雪盖显著减少;秋季长江源区雪盖面积显著增加;冬季雪盖变化差异较大,黄河、澜沧江和怒江源区雪盖面积在减少,但趋势不显著,长江和雅鲁藏布江源区雪盖面积在增加,但仅长江源区增加趋势显著.总体而言,五江源地区雪盖面积表现出略微增加的趋势,但不显著.