清河干流生态基流计算分析

根据清河干流八棵树水文站、开原水文站1988-2009年径流量资料,选取Tennant法、90%保证率最枯月平均流量法、NGPRP法等5种水文学方法对清河干流生态基流进行了计算,通过对各水文学方法计算结果的对比分析,发现Tennant法更适合用于清河干流生态基流的计算。根据不同水平年清河干流生态基流Tennant法的计算结果,并与清河干流实际径流进行对比分析,表明随着不同水平年降雨量的减少,清河干流生态需水的满足程度逐渐减小。     

渭河流域径流系数的演变规律研究

以渭河流域1960-2005年的径流系数资料为基础,将渭河流域分为北道以上、北道-林家村、林家村-咸阳、咸阳-临潼(含张家山)、临潼-华县+状头5个区域。分析了这5个区域和渭河流域径流系数的基本统计特征、年际变化,并运用R/S法进行持续性分析,Kendall秩次相关检验分析趋势性,功率谱分析法计算周期,Mann-Kendall法和累积距平法相结合分析突变。结果表明:渭河流域径流系数呈现显著的递减趋势并将继续持续下去,北道以上最显著周期为3年,北道-林家村最显著周期为2.66年,其他区域均无显著周期存在。径流系数突变发生在20世纪60年代末—70年代初、80年代—90年代初。由于人类活动和气候变化的影响,整体渭河流域降雨转化为径流的能力显著减弱并在未来还将继续减弱。     

Hydrological simulation approaches for BMPs and LID practices in highly urbanized area and development of hydrological performance indicator system

Urbanization causes hydrological change and increases stormwater runoff volumes, leading to flooding, erosion, and the degradation of instream ecosystem health. Best management practices （BMPs）, like detention ponds and infiltration trenches, have been widely used to control flood runoff events for the past decade. However, low impact development （LID） options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID stormwater management practices such as bioretention cells and porous pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices and the two BMPs of detention ponds and infiltration trenches in an existing hydrological model to estimate the impacts of BMPs and LID practices on the surface runoff. The modeling approach has been used in a parking lot located in Lenexa, Kansas, USA, to predict hydrological performance of BMPs and LID practices. A performance indicator system including the flow duration curve, peak flow frequency exceedance curve, and runoff coefficient have been developed in an attempt to represent impacts of BMPs and LID practices on the entire spectrum of the runoff regime. Results demonstrate that use of these BMPs and LID practices leads to significant stormwater control for small rainfall events and less control for flood events.     

滹沱河径流变化分析

通过对滹沱河流域代表站河道非汛期实测径流分析可以发现,从20世纪50年代到21世纪初,径流量减少为原来的1/3左右。非汛期上游河道来水量的减少,是造成河流下游水环境恶化的根本原因。大规模人类活动使流域下垫面情况发生了变异,使近年来同量级年降水条件下,天然年径流减少超过四成,而同时用水量占来水量的比例却在逐年增加,导致下游河道常年断流干涸,水环境严重恶化。以南水北调中线建成供水为契机,重新确立水库调度中防洪、供水和下游河流水环境保护的关系,是恢复河流水环境的必要途径。     

龙川江流域主要气象要素及径流变化趋势分析

采用Mann-Kendall非参数检验法对金沙江一级支流龙川江流域1970年-2009年逐月气温、降水及1961年-2008年径流资料进行趋势检验,并运用R/S方法分析流域的年平均气温、降水、径流时间序列的持续性,估算各项指标的Hurst指数,以定量估计未来气候及径流的变化趋势。结果表明:(1)过去几十年来,流域内降水呈上升趋势但不显著,未来降水将持续增加且元谋站降水的增长趋势持续性较强;(2)几十年来,流域气温呈显著上升趋势,未来气温将会持续过去的上升趋势;(3)几十年来,流域径流呈减少趋势,但不显著,未来继续呈下降趋势,但持续性不强。     

Impacts of water surface area of watershed on design flood简

In order to analyze the impact of the water surface area of a watershed on the design flood, the watershed was classified into a land watershed and a water surface watershed for flood flow calculation at the same time interval. Then, the design flood of the whole watershed was obtained by adding the two flood flows together. Using this method, we calculated design floods with different water surface areas of three reservoirs and analyzed the impact of water surface area on the flood volume and peak flow. The results indicate that larger water surface areas lead to greater impacts on the flood volume and peak flow. For the same watershed area, the impact of water surface area on the flood volume and peak flow is positively proportional to the flood frequency, i.e., the higher the frequency, the greater the impact becomes.     

医疗信息系统基础设施架构

医疗信息系统持续运行依赖于高可用的信息系统基础架构,传统的双机热备技术已不能满足当前的实际需求.从共享磁盘管理角度论述故障转移型群集新技术方案,从安全角度论述局域网高可用和业务流负载均衡实施技术,操作系统安全措施及终端管理.打造～个真实高可用的信息系统基础平台,清除计划内和计划外停机.保障医疗机构的日常业务,应用软件系...     

基于GPGPU的实时结肠虚拟展平技术

为了在结肠检查过程中实时绘制结肠内壁表面的展平图像,并动态地调整分割阈值,提出一种基于GPGPU的实时结肠虚拟展平技术.首先在结肠中心路径上每一点的切线方向建立圆柱形的光照模型,然后根据当前CT分割阈值,并通过GPGPU加速光线投射算法提取亚像素级的结肠内壁表面,最终得到局部虚拟展平的结果.实验结果表明,文中技术渲染速度达到50帧/s的实时要求,在结肠检查过程中能够通过动态地调整分割阈值获取精细的结肠内壁,提高了虚拟展平算法的适应性和准确性.     

THE EFFECT OF DIFFUSION ON CRYSTAL SIZE DISTRIBUTION IN A CONTINUOUS CRYSTALLIZER

A general steady-state model for the ideal, continuous, mixed suspension, mixed product removal crystallizer is developed in the tradition of Randolph and Larson. Relations derived from the mass balances lead to imposition of constraints on the functional form of the crystal growth rate expression. Application to power law and linear growth rate equations indicates that their parameters must satisfy specific inequalities. Crystal growth rate relations are developed which incorporate both surface reaction kinetics and diffusive mass transfer. Calculated crystal size distributions demonstrate a maximum in the curve which becomes more pronounced as diffusion resistance increases. Limited experimental data support the analysis.     

DRYING OF BIOLOGICAL PRODUCTS WITH SIGNIFICANT VOLUME VARIATION. EXPERIMENTAL AND MODELING RESULTS FOR POTATO DRYING.

ABSTRACT

This work is devoted to the experimental investigation and theoretical modeling of biological products with high initial moisture content which implies significant volume contraction. Firstly, experimental equipment which was designed to continuously determine variations in the global moisture content and in the temperature of the sample is introduced. Furthermore, the equipment is controlled by a PC which records experimental information in real time. In particular, measurement of the radial and temporal distributions of moisture content and temperature during the drying process of the homogeneous porous media potato are given. The mean moisture content and temperature curves are also given.