Liu G.W.,Nanjing Hydraulic Research Institute
Science China Earth Sciences | Year: 2012
This paper investigates the important scientific problem of river regulation strategies in the lower reaches of the Yellow River, and discusses the "geo-basis" of river regulation. The concept of a geo-basis to river regulation in the lower Yellow River was discussed in terms of subsidence and sedimentation features of the river plain; channel features, erosion characteristics of the Loess Plateau and storm-flood features of the middle and lower reaches. The geographic features of the lower Yellow River have gradually changed since the Holocene but there has been no fundamental change. Based on an analysis of the geo-attributes of the lower reaches of the Yellow River, several conclusions on its river regulation were made. The release of sediment should be the first measure of river regulation because of deposition in the lower reaches. The river channels should be provided with adequate space for wandering in the lower reaches. The tail river should be also provided with necessary wandering space because of weak marine dynamics in the estuary area and changes in the delta. Because the erosion environment of the Loess Plateau will not fundamentally change, river harnessing of the middle reaches should focus on improving the plateau morphology, which can be done by reducing the fragmentation of terrain and building a planation surface. Ecoremediation should focus on converting farmland to grassland. There may be extreme floods in the future, as has occurred previously, thus an extreme flood defense system should be considered for the lower reaches. A periodic law for regulation in the Yellow River is discussed. We also discuss how the current use of the lower reaches of the Yellow River is unsustainable and it is urgent to research artificial rechanneling and the creation of new flow paths for the lower reaches. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.
Shaowei H.,Nanjing Hydraulic Research Institute
Automation in Construction | Year: 2014
At present, there is no design specification for the pre-stressed composite beam. To research the bending mechanical behaviors of pre-stressed steel-concrete composite box beams and provide corresponding design specification and requirements, the tests of ten pre-stressed composite box beams were finished, and the effects on flexural behaviors were given for different initial pre-stress levels, the forms of reinforcement placement and loading method and so on. Design calculation methods under serviceability and bearing capacity limits were mainly discussed. Test results indicated that the pre-stressed composite beam displays a lot of advantages compared with ordinary composite beams. The flexural capacity of the composite beams through using pre-stressed technology was greatly increased. The elastic-plastic analysis of the pre-stressed composite beams was finished; what's more, the equations of deflection and elastic bearing capacity with consideration of interface slip were derived out. Calculating equations for ultimate banding capacity were derived with consideration of pre-stress increments. Finally, the calculated values met precise requirements when compared with the test results. This study provides advisory opinions for the designer to analysis and design of the pre-stressed composite beams. © 2013 Elsevier B.V.
Hu S.,Nanjing Hydraulic Research Institute |
Hu S.,Northwestern University
Applied Clay Science | Year: 2013
When the angular velocity of a circular disk at room temperature is gradually increased the disk first of all behaves elastically, then, at a certain velocity, plastic yielding begins and proceeds, with work-hardening, until all the material of the disk has reached the initial yield point, Further increase in speed causes unrestricted plastic flow to take place. The system is stable as long as an increase in speed is necessary to produce further plastic flow. In the paper, theoretical analysis in polar coordinate of the elastic-plastic interface under rotating status was finished, The calculated results are given out in exact solution. The formula of large deformation analyses of rotating disk were derived out of an equation group which could become into seven independent equations with seven unknowns and can be solved by COLSYS software. Then, some calculated examples were given out. The bursting speed of rotating disk was analyzed. © 2013 Elsevier B.V.
Zhan C.-S.,CAS Institute of Geographical Sciences and Natural Resources Research |
Song X.-M.,Nanjing Hydraulic Research Institute |
Xia J.,CAS Institute of Geographical Sciences and Natural Resources Research |
Tong C.,Lawrence Livermore National Laboratory
Environmental Modelling and Software | Year: 2013
Efficient sensitivity analysis, particularly for the global sensitivity analysis (GSA) to identify the most important or sensitive parameters, is crucial for understanding complex hydrological models, e.g., distributed hydrological models. In this paper, we propose an efficient integrated approach that integrates a qualitative screening method (the Morris method) with a quantitative analysis method based on the statistical emulator (variance-based method with the response surface method, named the RSMSobol' method) to reduce the computational burden of GSA for time-consuming models. Using the Huaihe River Basin of China as a case study, the proposed approach is used to analyze the parameter sensitivity of distributed time-variant gain model (DTVGM). First, the Morris screening method is used to qualitatively identify the parameter sensitivity. Subsequently, the statistical emulator using the multivariate adaptive regression spline (MARS) method is chosen as an appropriate surrogate model to quantify the sensitivity indices of the DTVGM. The results reveal that the soil moisture parameter WM is the most sensitive of all the responses of interest. The parameters Kaw and g1 are relatively important for the water balance coefficient (WB) and Nash-Sutcliffe coefficient (NS), while the routing parameter RoughRss is very sensitive for the Nash-Sutcliffe coefficient (NS) and correlation coefficient (RC) response of interest. The results also demonstrate that the proposed approach is much faster than the brute-force approach and is an effective and efficient method due to its low CPU cost and adequate degree of accuracy. © 2012 Elsevier Ltd.
Zhu D.,Nanjing Southeast University |
Zhu D.,Nanjing Hydraulic Research Institute
Coastal Engineering | Year: 2011
The present paper extends the impedance analytical method to the study of the interaction of regular plane waves with a row of rectangular piles. The dissipative energy is estimated from the flow resistance for the row of piles. Formulas of wave reflection and transmission coefficients and the wave force for the row of piles are derived. Predictions obtained using the present model agree with experimental data in the literature. © 2011 Elsevier B.V.