Development and application of a spatially‐distributed Arctic hydrological and thermal process model (ARHYTHM)

A process‐based, spatially distributed hydrological model was developed to quantitatively simulate the energy and mass transfer processes and their interactions within arctic regions (arctic hydrological and thermal model, ARHYTHM). The model first determines the flow direction in each element, the channel drainage network and the drainage area based upon the digital elevation data. Then it simulates various physical processes: including snow ablation, subsurface flow, overland flow and channel flow routing, soil thawing and evapotranspiration. The kinematic wave method is used for conducting overland flow and channel flow routing. The subsurface flow is simulated using the Darcian approach. The energy balance scheme was the primary approach used in energy‐related process simulations (snowmelt and evapotranspiration), although there are options to model snowmelt by the degree‐day method and evapotranspiration by the Priestley–Taylor equation. This hydrological model simulates the dynamic interactions of each of these processes and can predict spatially distributed snowmelt, soil moisture and evapotranspiration over a watershed at each time step as well as discharge in any specified channel(s). The model was applied to Imnavait watershed (about 2·2 km²) and the Upper Kuparuk River basin (about 146 km²) in northern Alaska. Simulated results of spatially distributed soil moisture content, discharge at gauging stations, snowpack ablations curves and other results yield reasonable agreement, both spatially and temporally, with available data sets such as SAR imagery‐generated soil moisture data and field measurements of snowpack ablation, and discharge data at selected points. The initial timing of simulated discharge does not compare well with the measured data during snowmelt periods mainly because the effect of snow damming on runoff was not considered in the model. Results from the application of this model demonstrate that spatially distributed models have the potential for improving our understanding of hydrology for certain settings. Finally, a critical component that led to the performance of this modelling is the coupling of the mass and energy processes. Copyright © 2000 John Wiley & Sons, Ltd.     

GEOMORPHOLOGICAL TRANSFER FUNCTION CALCULATED FROM DIGITAL ELEVATION MODELS FOR DISTRIBUTED HYDROLOGICAL MODELLING

Recently, several attempts have been made to relate the hydrological response of a catchment to its morphological and topographical features using different hypotheses to model the effect of the drainage network. Several transfer functions were developed and some of these are based on the theory of a linear model, the geomorphological unit hydrograph. The aim of this paper is to present a methodology to automatically identify the transfer function, using digital elevation models for applications in distributed hydrological modelling. The transfer function proposed herein is based on the Hayami approximation solution of the diffusive wave equation especially adapted for the routing hydrograph through a channel network. The Gardon d’Anduze basin, southern France, was retained for applications. Digital elevation models were used to extract the channel network and divide the basin into subcatchments. Each subcatchment produces, at its own outlet, an impulse response which is routed to the outlet of the whole catchment using the diffusive wave model described by two parameters: celerity and diffusivity functions of geometrical characteristics of the channel network. Firstly, a geomorphological unit hydrograph obtained by routing a homogeneous effective rainfall was compared with the unit hydrograph identified by a lumped model scheme, then the distributed model was applied to take into account the spatial variability of effective rainfall in the catchment. Results show that this new method seems to be adapted for distributed hydrological modelling; it enables identification of a transfer function response for each hydrological unit, here subcatchments, and then simulation of the contribution of each unit to the hydrograph at the outlet. © 1997 by John Wiley & Sons, Ltd.     

分布埋入式光纤与隧道衬砌耦合性能试验及应用

为探究埋入式光纤与隧道衬砌的耦合性能,分别从理论与试验两个方面进行研究,并在实际工程中进行了验证。构建了光纤、中间体和基体结构力学分析模型,进行光纤应变传递机制理论分析,计算了光纤应变传递效率;使用钢筋混凝土梁模拟隧道衬砌,进行了2组不同加载速率的试验。其中,在同一根梁内（同一工况）设计6种光纤的布设方式,以位移控制的方式在梁跨中部位进行单点多级加载,使用BOFDA（布里渊散射光频域分析）技术分别对6条光纤进行监测。试验结果表明：6条光纤均可以有效监测梁从开始加载至钢筋开始屈服阶段,光纤与梁耦合性最好;钢筋开始屈服直至梁破坏阶段,光纤应变不再增加甚至减小或呈现出光纤断裂的状态,此过程光纤与梁耦合性较差;除开槽埋入式光纤的有效监测应变差为3 000×10?6外,其余布设方式光纤有效监测应变差为2 000×10?6;光纤在长距离（>>146 mm）埋入式布设情况下可认为其应变传递效率接近100%,2组不同试验结果呈现相似规律。在北京市新机场线地铁暗挖隧道CRD工法区间进行了工程应用研究,监测结果表明分布埋入式光纤布设工艺是可行的,可为分布式光纤技术在地下工程结构监测中的应用提供有价值的参考。     

分布式数据库Greenplum在地震前兆数据存储中的应用

随着地震前兆观测台网的加密、采样率的提高,地震前兆观测数据量也在快速增加。在进行地震数据共享服务时,需要快速获得大量数据集,无疑对前兆共享数据库的数据处理能力提出了更高的要求。针对这一问题,提出基于Greenplum数据库的地震前兆数据存储设计方案。通过搭建Greenplum分布式数据库环境,实现了海量前兆数据的快速处理,并与传统Oracle数据库进行对比,结果表明:Greenplum数据库读取前兆数据耗时更低,对于大批量数据的读取操作,Greenplum数据库的优势更加明显;Greenplum数据库良好的可扩展性和对应用编程接口(JDBC、ODBC)的支持,使得其在前兆数据分析处理中的应用前景广阔。     

A semi‐distributed parallel‐type linear reservoir rainfall‐runoff model and its application in Taiwan

The main purpose of this paper is to introduce a semi‐distributed parallel surface rainfall‐runoff conceptual model. In this paper, a general solution of the instantaneous unit hydrograph (IUH) has been derived successfully for N linearly connected reservoirs, each having a different storage constant. The solution is a function of geomorphologic parameters, meteorologic factors and roughness coefficients. The model also takes into account the hydrologic response which is influenced by outflow downstream of a reservoir. For calibration, the shuffled complex evolution (SCE) algorithm is used to search for the global optimal parameters of the model. Because of the parallel structure, the mean roughness parameter of the channel becomes a “conceptual” parameter without a real physical meaning. To evaluate the adaptability of the model adopted, three watersheds around the city of Taipei in Taiwan were chosen to test the effectiveness of the model. The study provides an appropriate rainfall‐runoff model for planning flood mitigation in Taiwan. Copyright © 1999 John Wiley & Sons, Ltd.     

Development and application of a distributed catchment-scale hydrological model for the River Ythan,NE Scotland

Mathematical models are being used to develop a decision support system for integrated management of the Ythan catchment in NE Scotland. One component of this has involved the development of a distributed catchment-scale hydrological model. The model is based on subsurface flow routing and calculates the contribution to stream flow from each 50 m×50 m cell in the 548 km² catchment. It uses two topographic parameters, slope and distance to stream following the main line of flow, and five physical parameters. The topographic analysis and distributed flow accumulation are performed by linking the single cell model with a geographic information system. Preliminary results from a three-year simulation of daily flows indicate that the model successfully predicts the main characteristics of the catchment flow. © 1998 John Wiley & Sons, Ltd.     

基于BOFDA的地面塌陷变形分布式监测模型试验研究

地面塌陷变形作为一种分布广泛的地质灾害已成为目前城市发展中亟待解决的一个问题。文章使用布里渊光频域分 析（BOFDA）技术对地面塌陷变形进行分布式监测模型实验研究。利用自制的地面塌陷物理模型,对不同类型、不同厚度 土体在塌陷过程中的变形进行分布式光纤监测,并对其试验结果进行对比分析。结果表明：基于BOFDA分布式光纤传感技 术可有效捕捉到地面塌陷变形的发生和发展过程,并较为准确地反映出地面的塌陷变形规律。研究结果为该技术在地面塌 陷变形监测的推广应用提供一定的参考依据。     

A distributed parameter model of a frame pin‐supported wall structure

Many reinforced‐concrete frames collapse via a soft‐story mechanism during severe earthquakes. Such collapses are mainly attributed to concentrated deformation in a soft story. Deformation control is thus important in preventing collapse. The frame pin‐supported wall structure is a type of rocking structure that releases constraints at the bottom of the wall. Previous research has obtained good results for the deformation control of this type of structure. However, the interior forces and strength demands of the pin‐supported wall have not been systematically explored. In this paper, a distributed parameter model is developed to investigate the strength demand of the wall in a frame pin‐supported wall structure. In the model, the pin‐supported wall is simplified as a bending beam and the frame is simplified as a shear beam. The two beams are joined by distributed shear connectors, so that the shear force can be transferred at any location on the interface. The model can be solved using differential equations based on equilibrium and compatibility. The accuracy of the model is verified using SAP2000 (Computers and Structures Inc., Berkeley, CA, USA). Displacement distribution of the structure and distributions of the moment and shear force within the pin‐supported wall are obtained for two typical external force profiles. It is found that the pin‐supported wall can effectively reduce the drift concentration factor. Distributions of the displacement, moment, and shear force are closely correlated with the relative stiffness of the wall and frame. Finally, recommendations on the stiffness and strength of a pin‐supported wall are made. Copyright © 2015 John Wiley & Sons, Ltd.     

基于密度的线数据分组算法研究

目前,地理空间数据面临着由于数据量膨胀和计算量高速增长而引起算法效率低的问题,采用"分而治之"的数据分组策略提高运算效率已成为研究的热点。面向分布不均匀的线数据,本文提出了基于密度的线数据分组算法(简称LGAD)。首先,算法通过查找高密度区提取样本线段,保证了分组算法的起点落到高密区;其次,考虑线空间拓扑关系的复杂性,引用水平、垂直和夹角距离度量线段间距离,创建样本线段与其他线段的距离矩阵;最后,以距离矩阵和最优选择方法实现数据负载均衡分组。实验结果显示,对数据分组和分组后数据进行线段聚类的2个过程中,该算法体现了较好的时间优势,与串行计算相比,在分组数为2-12 时,平均比率达4.3,提高了应用的响应速度,具有较好的实际意义。     

Real‐time distributed hybrid testing: coupling geographically distributed scientific equipment across the Internet to extend seismic testing capabilities

Large‐scale testing and qualification of structural systems and their components is crucial for the development of earthquake engineering knowledge and practice. However, laboratory capacity is often limited when attempting larger experiments due to the sheer size of the structures involved. To overcome traditional laboratory capacity limitations, we present a new earthquake engineering testing method: real‐time distributed hybrid testing. Extending current approaches, the technique enables geographically distributed scientific equipment including controllers, dynamic actuators and sensors to be coupled across the Internet in real‐time. As a result, hybrid structural emulations consisting of physical and numerical substructures need no longer be limited to a single laboratory. Larger experiments may distribute substructures across laboratories located in different cities whilst maintaining correct dynamic coupling, required to accurately capture physical rate effects. The various aspects of the distributed testing environment have been considered. In particular, to ensure accurate control across an environment not designed for real‐time testing, new higher level control protocols are introduced acting over an optimised communication system. New large time‐step prediction algorithms are used, capable of overcoming both local actuation and distributed system delays. An overview of the architecture and algorithms developed is presented together with results demonstrating a number of current capabilities. Copyright © 2013 John Wiley & Sons, Ltd.