精密水深测量中延时效应的研究

利用GPS RTK 进行无验潮模式下的精密水下地形测量时,延时改正对于实现定位和测深的同步以及最终成果的质量具有重要的影响.针对传统方法的局限性,研究了两种延时确定方法,即特征点对法和断面一致性原则,并给出了相应的延时确定模型,并用实际资料进行了验证,理论分析和实际验证结果证明,通过延时改正有效地消除了系统性延时对测深定位所产生的影响,从而确保了测量成果的质量.     

一种适用于冲锋舟的回声仪安装支架

在水塘、库汊中开展水下地形测量工作,由于水深浅不一,大船容易搁浅,只能选择吃水较浅的冲锋舟作为主测船.由于水体的不连通,测量过程中需要经常搬运船只,回声仪需要不停地拆卸和安装,传统的回声仪安装架不仅笨重而且拆卸困难,严重影响水下测量作业效率.因此,需要我们研发出拆装简单,质量轻的回声仪安装支架.笔者结合生产实际,先介绍...     

精密单波束测深分析与实践

随着对多波束系统组成单元的研究不断深入,多传感器集成技术已从传统单波束测深向精细化方向发展.在分析普通单波束测深精度因子的基础上,重点针对延时效应、动吃水效应和波束角效应进行了分析和试验.试验结果表明:对于中高速运行的测船测深作业,应进行延时改正;采用波束角小的换能器以无验潮模式进行单波束测深可有效提高测深精度.得出了...     

浅地层剖面仪在淤泥厚度探测中的应用

主要讨论了声波在淤泥厚度探测中的原理和浅地层剖面仪在淤泥厚度探测中实施步骤和数据处理过程中的注意事项,以及分析了浅地层剖面仪探测沉积层厚度的探测误差来源和改正方法。     

ADCP·流速仪流量相关系数分析

介绍了ADCP基本原理,通过ADCP法与常规流速仪法测流资料进行对比、分析比测资料,率定ADCP与流速仪法的相关系数.通过系数改正,以达到解决在缺乏外部设备、提高仪器使用精度、正式投产应用的目的..     

偏角改正表的验证和编制说明

采用流速仪进行测量时,由於入水後的悬索、铅鱼和流速仪受水流冲击的影响,使悬索随水移向下游,产生不同程度的悬索偏角。而其悬索偏角的大小,则往往决定於垂线上的流速分布,以及采用的悬索粗细和铅鱼的重量与型式。一般在36°以下,我们可以参照路其谢姓或华东丛刊所载的偏角表进行偏角改正,以确定仪器的施放位置。但是超过上述范围,这些改正表即失掉了使用价值。纵令勉强采用直线的插补方法,或根据假定的曲线型式进行公式有推演,这样处理和改正的结果与实际     

大水深测量校正方法研究与应用

水库水深测量精度直接关系到水库的防洪安全与蓄水兴利。现有回声测深仪无法应对大水深施测的情况，且测量受到水库水温分层影响。利用回声测深仪配合校正标进行大水深测量的校正方法，能够精确检测到回声测深仪水深测量的误差及差值、系统延时问题等，通过与各级校正标的真值比较、修正，能使测值近似真值,且使误差控制在容许范围内。介绍了水深校正标基本原理、操作方法和步骤以及在水库测深中的应用。     

一种回声测深远程校准仪的研制

为实现回声测深仪主机精确计量检定及远程在线计量检定问题,开发了一种回声测深远程校准系统。采用STM32单片机作为数据采集的核心元件,包括电源供电模块、信号处理接收模块、信号发生输出模块、显示延时控制模块、信号通信交互模块;通信模块通过USB串口、RS485及无线WIFI网络系统,实现回声测深仪主机的远程在线校准和远程交互。试验结果表明:该回声测深远程校准系统检定精度符合国家计量检定标准(最大允许误差为±1%d,其中d为实测水深值),且远程校准测试和现场校准测试误差率在2%以内。该回声测深远程校准仪系统为进一步推广远程在线计量研究打下了坚实基础。     

手持电波流速仪在洪水流量测验中的应用与分析

手持式电波流速仪是专用于测量水面流速的仪器,适合在洪水期使用,尤其适用于野外巡测中的洪水应急测量。本文通过电波流速仪在爱河铁佛寺水文站与转子式流速仪的对比观测资料,进行相关分析,率定其在山溪性河流中高水流速测验的流速改正系数,寻求其在国家基本水文站洪水流量测验中的应用途径。     

丹江口水库回声仪测深比测精度分析

丹江口水库是南水北调中线工程水源地,水库淤积状况备受世人关注,淤积规律研究对三峡水利枢纽等工程有重大借鉴作用.通过总结影响回声仪测深精度的仪器性能、传播介质、反射位置、反射界面等4大基本因素,认识到水库床面分强、弱、中反射面.通过对多种回声仪在重点淤积库段同步进行定点测深并结合淤积物容重、粒径分布等观测数据,对比测数据进行了统计分析.     

THE RELATIONSHIP BETWEEN THERMAL REGIME ALTERATION AND SPAWNING DELAY OF THE FOUR MAJOR CHINESE CARPS IN THE YANGTZE RIVER BELOW THE THREE GORGES DAM

Large dams often alter flow and thermal regimes downstream, resulting in fish spawning delays and larval abundance declines. Accurate prediction of the delayed spawning period under changed thermal regime is critical for selecting a correct timing to modify dam operation and to release the environmental flow needed to enhance fish spawning. We used correlation analysis to investigate the relationship between thermal regime alteration and spawning delay of the four major Chinese carps (FMCC) below the Three Gorges Dam in the Yangtze River, China, using a 13‐year ecological data series (1997–2009). Eighteen variables were defined to quantify thermal regime and related to two variables representing spawning timing. Our results demonstrate that the start of FMCC spawning has been delayed from early May to middle June since the Three Gorges Dam initiated operation in 2003. Water temperature declines of 2 °C–4 °C in March, April and May (a critical period for gonad development) were the principal reason for the observed spawning delay. The variable most associated with spawning timing was the arrival date of the cumulative temperature needed for gonad development from stages IV to V (D_DegDayIV–V), which describes the long‐term impacts of the timing, magnitude and duration of thermal regime upon gonad development. Only the cumulative temperature for gonad development and the minimum temperature for FMCC spawning (18 °C) are both satisfied, the occurrence of suitable flow conditions, that is, flow increase or flash flood, would produce a successful spawning event. Consequently, we suggest that the experimental flow increase process of the Three Gorges Reservoir aimed at enhancing FMCC spawning should initiate after 15 June when the requisite thermal regime can be met. Copyright © 2013 John Wiley & Sons, Ltd.     

浅析CSTR水质模型在赣江流域的应用

利用CSTR模型的方法建立了适应于赣江流域复杂河流系统的水质模型，对可以获得的赣江流域水质模型数据进行了分析，同时还对模型进行了验证．结果表明：所建立的水质数学模型能够达到赣江流域预定的规划目标的要求，模似的结果是比较可靠．只是水文数据在空间上比较稀疏，污染源统计数据可信度比较低，但单个水文站点能够比较好地反映流量和其它水文参数的时间变化过程．     

DYNAMIC CORRECTION OF ROUGHNESS IN THE HYDRODYNAMIC MODEL

Based on the hydrodynamic model and the Xinanjiang model, the river stage forecasting model has been proposed. But its performance is not satisfactory as applied to estuary areas. River roughness is a sensitive parameter in the hydrodynamic model, and its value is related to some substantial uncertainties in the tidal river. According to roughness tests, a new method of roughness dynamic correction was developed to improve the performance of the stage model. The method was focused on the usage of observed data for the studied section, and its parameters were analyzed. Nested with the dynamic correction of roughness, the stage model was applied to the tidal reach of the Caoe River. The results demonstrate that the roughness dynamic correction can improve the simulation accuracy of the stage model, and especially has the capacity of reducing the errors at peak stages.     

FINITE ELEMENT ANALYSIS OF LAMINAR FLOW AND HEAT TRANSFER IN A BUNDLE OF CYLINDERS

In this paper two-dimensional Navier-Stokes equations and energy equation governing incompressible laminar flow past a bundle of cylinders were numerically solved by using the finite element method.The velocity correction method was used for time advancement, and spatial discretization was carried out with the Galerkin weighted residual method.Viscous flows past the cylinder banks arranged in in-line cylinder bundles and staggered cylinder bundles, coupled with heat transfer, were investigated for pitch-diameter ratios of 1.5 and 2.0 and the Reynolds numbers from 50 to 500.Flow structures and heat transfer behavior were discussed.The results obtained agree well with available numerical data.     

THE PARALLEL CALCULATION METHOD OF INCOMPRESSIBLE VISCOUS FLOW IN CYLINDRICAL PASSAGE

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FINITE ELEMENT ANALYSIS OF THE FLOW INDUCED BY ROTATING BLADES IN AN INCOMPRESSIBLE VISCOUS FLUID

Aerodynamic loads on a multi-bladed helicopter rotor in hovering flight were calculated by solving the three-dimensional incompressible Navier-Stokes equations. The rotor wake effects were accounted by the correction of local geometric angle of attack according to a free-wake modeling in addition to an empirical modification for the tip flow effect. The validity and efficiency of the present method were verified by the comparisons between numerical results and experimental data.     

数据复制技术在防汛网络系统应用初探

在分析防汛网络系统的实时水情信息采集系统结构和特点的基础上，初步探讨了一种适用于防汛网络系统的实时情信息采集系统中数据复制服务技术。     

Regional estimation of short duration rainfall extremes

The present study proposes a method for estimating the distribution of short-duration (e.g., 1 hour) extreme rainfalls at sites where data for the time interval of interest do not exist, but rainfall data for longer-duration (e.g., I day) are available (partially-gaged sites). The proposed method is based on the recently developed “scale-invariance” (or “scaling”) theory. In this study, the scaling concept implies that statistical properties of the extreme rainfall processes for different temporal scales are related to each other by a scale-changing operator involving only the scale ratio. Further, it is assumed that these hydrologic series possess a simple scaling behaviour. The suggested methodology has been applied to extreme rainfall data from a network of 14 recording raingages in Quebec (Canada). The Generalised Extreme Value (GEV) distribution was used to estimate the rainfall quantiles. Results of the numerical application have indicated that for partially-gaged sites the proposed scaling method is able to provide extreme rainfall estimates which are comparable with those based on available at-site rainfall data.     

大坝自动化监测数据的漂移校正

应用统计学原理，研究了对大坝自动化监测数据的区间性漂移进行校正的方法。首先，分别对测值序列中各段无漂移的子系列，以监测效应量(子系列效应量的平均值)的波动值作为因变量、以环境因子(子系列因子的平均值)的波动值作为自变量，逐段准备数据；之后，将各区段中准备好的数据融合在一起，进行全序列的回归分析；最后，根据回归分析的结果及漂移前后环境量的区段平均变化程度估计漂移量，并对测值进行校正，给出了具体的校正公式。此外，通过方差分析对校正精度进行了估计。