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Shi Z.,Guangdong Hydropower Planning and Design Institute | Gao Z.,Jiangsu Hydraulic Engineering Construction Co.
Applied Mechanics and Materials

A mathematical model for the soil-water characteristic curve is proposed in the light of bounding surface plasticity. The main drying and wetting curves are taken as the asymptotes of the scanning curves, and only one additional parameter is introduced to simulate such scanning curves. To pave to the way for the application of the proposed model, the governing equation of unsaturated seepage problems and the finite element formulations are derived. A FEM program incorporating the SWCC model is then developed and used to study the hydraulic behaviour of an earth dam undergoes a repeated change of reservoir level. Numerical results confirm the possibility and necessity of using such a hysteresis model in unsaturated seepage problems. © (2011) Trans Tech Publications, Switzerland. Source

Wang X.,Sun Yat Sen University | Chiu C.-H.,Sun Yat Sen University | Guo W.,Guangdong Hydropower Planning and Design Institute
Mathematical Problems in Engineering

We construct the mathematical models to find the optimal allocation of the module's capacity (module members) to different assembly operations in a module for given garment assembly tasks in a modular production system. The objectives of the models are minimizing the holding cost for work in process (WIP) inventories in the module and the total deviation of the WIP inventories from their corresponding target values in the module during a specific time interval. The solutions of the models can be used as reference to achieve better allocation of the module members to different operations in a module to fulfill the given garment assembly tasks. © 2014 Xiaoqing Wang et al. Source

Wang Y.,Nanjing University of Aeronautics and Astronautics | Wang Y.,Guangdong Hydropower Planning and Design Institute | Lu Z.,Nanjing University of Aeronautics and Astronautics | Guo T.,Nanjing University of Aeronautics and Astronautics
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics

The flow field of simple terrain is described by a linearization of the flow equations. And the computational method is further simplified based on the characteristic of atmospheric boundary layer(ABL), namely, with a so-called topographic effects coefficient, the flow velocity is obtained quickly on the point (generally wind turbine's sites) being interested in. For wake effects, a modified Park model is used, which has been involved in wind farm design. The wake effects of wind turbines are linearly superimposed and the smaller ones are neglected. A typical-built seashore wind farm is introduced, including its total rated capacity, roughness of the ground and wind data measuring situation. Then as a calculating example, the power production of the wind farm is predicted by using different wind data. Most predicted values coincide well with the measured ones. Finally, it is explored why the output of each wind turbine is so different, and the conclusion presents that the size of topographic maps can influence the accuracy of wind field simulation. Also, definite suggestion about this is proposed for engineering design. Source

Li Z.,Hohai University | Li Z.,Guangdong Hydropower Planning and Design Institute | Hao Z.,Hohai University | Shi X.,CSIRO | And 4 more authors.
Global and Planetary Change

To help the decision making process and reduce climate change impacts, hydrologically-based drought indices have been used to determine drought severity in the Tarim River Basin (TRB) over the past decades. As the major components of the surface water balance, however, the irrigation process and reservoir operations have not been incorporated into drought indices in previous studies. Therefore, efforts are needed to develop a new agricultural drought index, which is based on the Variable Infiltration Capacity (VIC) model coupled with an irrigation scheme and a reservoir module. The new drought index was derived from the simulated soil moisture data from a retrospective VIC simulation from 1961 to 2007 over the irrigated area in the TRB. The physical processes in the coupled VIC model allow the new agricultural drought index to take into account a wide range of hydrologic processes including the irrigation process and reservoir operations. Notably, the irrigation process was found to dominate the surface water balance and drought evolution in the TRB. Furthermore, the drought conditions identified by the new agricultural drought index presented a good agreement with the historical drought events that occurred in 1993-94, 2004, and 2006-07, respectively. Moreover, the spatial distribution of coupled VIC model outputs using the new drought index provided detailed information about where and to what extent droughts occurred. © 2016 Elsevier B.V. Source

Cen W.-J.,Hohai University | Wang J.,Hohai University | Wang S.,Guangdong Hydropower Planning and Design Institute | Xiong K.,Chang Jiang Survey Planning Design and Research LLC
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

Rapid drawdown of reservoir has a great influence on the seepage, deformation and stability of an earth-rock dam. Under earthquakes, it may pose a new threat to the dam safety. Combined with a 300 m-super high core wall earth-rock dam to be constructed, the unsteady and saturated-unsaturated seepage analysis of the dam under the rapid drawdown of reservoir is carried out and the pore water pressure is acquired. Based on the seepage and static stress field, the seismic response of the dam is analyzed to get the basic dynamic response. Meanwhile, the evaluation of seismic stability and permanent deformation of dam slope are also conducted to evaluate its seismic safety. The results show that rapid drawdown of reservoir mainly affects the distribution of pore water pressure of the core and upstream dam body, causes the large change of static average effective stress field of the upstream region of the dam for the high core wall rockfill dams with good barrier performance core and upstream filter protection. The occasional earthquake will significantly affect the dynamic response and the seismic performance of upstream dam slope, and more attention should be paid to it. The change of water level does not affect the distribution of seepage field of the downstream dam body obviously. Therefore, the rapid drawdown of reservoir has little influence on the seismic safety of downstream dam body. Source

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