An optical tachometer for short‐path measurement of flow speeds in shallow overland flows: improved alternative to dye timing

Tracers, such as ?uorescein dye, are widely employed to measure overland ?ow speeds by time‐of‐travel along measured ?ow paths. Among several disadvantages of this method are the involvement of human reaction time when using stop‐watches, and the relatively long travel path that is consequently needed for reliable timing. Long ?ow paths mean that local variability along the ?ow path cannot be detected. This paper describes a new optical tachometer that overcomes these limitations, as well as offering other advantages. It is based on the use of a small ?oating re?ector target that is carried on the surface tension ?lm, and which passes between two re?ective sensors mounted above the ?ow. The new device allows virtual ‘spot’ measurements of surface ?ow speed over a path as short as 1 cm, and eliminates the in?uence of human reaction time. The new device is battery powered and portable, and provides an improved alternative to dye timing in many ?eld and laboratory applications. Its use will allow the collection of more re?ned data than have hitherto been easily achievable. Copyright © 2003 John Wiley & Sons, Ltd.     

Estimating formation conditions of ore-bearing trap intrusions (example of Noril'sk I intrusion)

Studies of vein and wallrock parageneses and geochemistry and analyses of fluids trapped in mineral inclusions in the epithermal fluorite deposits of Transbaykalia, supplemented by studies of fluorite deposition at active hot springs, provide the basis for the geochemical aspects of a genetic model. The fluorine appears to be magmatogenic, carried in the form of silicofluoride complexes in near-neutral solutions, and precipitated by calcium either released during argillization of the wallrocks or present in calcium-bearing ground water.     

气候变化对洪水频率和洪峰流量的影响

以月平均流量和月最大洪峰流量的相关关系为基础,建立了洪水频率评价模型,并用非参数方法估计各级流量的条件概率.利用月水量平衡模型求得未来不同气候变化情况下的月均流量过程,并探讨气候变化对洪峰流量及洪水频率的影响.东江和汉江部分流域的应用结果表明,降水变化对洪水频率和洪峰流量的影响要比气温变化对其的影响敏感得多,气温升高2℃,降水增加10%～20%,2年一遇的洪水频率要相应增加19.1%～47.4%;20年一遇的洪峰流量要增加10.2%～24.1%.     

网上购物对实体零售的影响

在互联网时代,商业中心受到新兴信息技术的冲击日益显著,成为新经济对城市空间影响效应的集中体现。本文以上海南方商城商业中心为例,通过消费者问卷调查与实地商家访谈探讨了网上购物对实体零售的影响效应。总体而言,网购频率对实体购物的影响呈正态分布的形式,高频和低频网购者产生高频实体购物的可能性较低,而中频网购人群具有更高的实体购物频率。从消费者内在决策过程分析,网购一方面降低了消费者对实体零售空间的满意度,但另一方面也刺激了消费者需求的增长,催生出更多的休闲娱乐消费行为。因此,网购对实体零售业及其消费者所带来的影响是复杂的,决策过程中不同方面受到的影响不尽相同。最后对商业中心的应对策略进行了分析讨论。     

强余震和主震地面运动分布比较研究

应用地震动衰减关系计算了1966年邢台地震以来中国大陆及近海发生的21次MSge;7地震序列的主震和强余震产生的有效峰值加速度，并对计算结果进行了比较分析， 发现76.2%地震序列的强余震产生的有效峰值加速度超过主震，其中50%多的强余震产生的有效峰值加速度在大范围内大幅度地超过主震. 本研究表明在强余震震中区附近，强余震往往会造成比主震更严重的破坏， 因此在地震危险性分析中要充分考虑强余震的影响场，才能为抗震设防提供科学、安全、可靠的依据.      

Time-related capture zones for radial flow in two dimensional randomly heterogeneous media

We consider the effect of randomly heterogeneous hydraulic conductivity on the spatial location of time-related capture zones (isochrones) for a non-reactive tracer in the steady-state radial flow field due to a pumping well in a confined aquifer. A Monte Carlo (MC) procedure is used in conjunction with FFT-based spectral methods. The log hydraulic conductivity field is assumed to be Gaussian and stationary, with isotropic exponential correlation. Various degrees of domain heterogeneity are considered and stability and accuracy of the MC procedure is examined. The location of an isochrone becomes uncertain due to heterogeneity, and it is strongly influenced by hydraulic conductivity variance. The probability that a particle released at a point in the aquifer is pumped by the well within a given time is identified. We propose a new expression for the probabilistic spatial distribution of isochrones, which is formally similar to the analytical solution for a uniform medium and takes into account the effects of heterogeneity.     

Estimation of peak streamflows through channel geometry / Estimation de pics de débit fluviatiles à l'aide de la géométrie des cours d'eau

Abstract

Knowledge of peak discharge is essential for safe and economical planning and design of hydraulic structures. In India, as in most developing countries, the majority of river basins are either sparsely gauged or not gauged at all. The gauged records are also of short length (generally 15–30 years), therefore development of robust models is necessary for estimation of streamflows. Various studies reveal that flood estimation through channel geometry is an alternative method for ungauged catchments. It is appropriate for use where flow characteristics are poorly related to catchment area and other catchment characteristics. In the present study, stream geometry parameters for 42 river sites in central-south India were used; calibration equations were developed with data for 35 stations and tested on data for the remaining seven stations. The relationships developed between mean discharge and channel geometry parameters provide an alternative technique for estimation of mean annual channel discharge.     

中国古建筑抗震性能分析

本文根据我国古建筑在历次地震作用下的结构破坏状况,总结了古建筑结构的震害特点,介绍了古建筑抗震性能分析方法,结合泰安市古建筑实例进行了抗震性能分析并给出了抗震性能分析结果。     

时空协同的城市旅游行程规划模型构建

传统的旅游行程规划往往仅被归类为空间排序问题,而对行程安排中时空耦合性与游客自身选择的灵活性考虑不足。本文将行程规划问题的理解从空间视角拓展至游客活动视角,从旅游节点时空耦合关系以及重构模式出发,将旅行中涉及到的时间、空间与专题等多维属性有机组织,进而提出行程时空链的概念模型以及行程要素时空衔接方法。研究以南京为案例展开模型实验,结果显示该模型与传统线路设计方法在节点名称、节点数量以及节点顺序等指标的匹配度均超过了80%,体现出较好的应用可靠性。相较于已有研究仅从空间视角展开的论述,本文提出以游客自身作为行程规划的基本单位,从游客行为选择、游览时间序列以及节点线路串联等多维视角进行映射耦合,以期为拓展深化城市旅游线路设计理论,支撑智慧旅游工程精细化建设提供理论支撑与借鉴。