Zhao Z.-C.,China Water Resources Beifang Investigation Design and Research Co. |
Feng S.-Y.,China Agricultural University |
Huo Z.-L.,China Agricultural University |
Jiang J.,China Agricultural University |
Qin J.-T.,China Agricultural University
Chinese Journal of Applied Ecology | Year: 2010
A field experiment was conducted to study the distribution characteristics of water and salt in a spring wheat soil under brackish water irrigation. Three irrigation quota ( 100% ETc, 80% ETc, and 60% ET C) and three water salinity levels (0. 7, 3 and 6 g -L-1) were installed. The results showed that soil water distribution was affected by irrigation quota and soil texture. Sufficient irrigation made the irrigation water stored in deeper soil layers ; while insufficient irrigation made the irrigation water more stored in top soil layer. Under the same irrigation quota, the salt accumulation in soil body increased with increasing water salinity; while under the same water salinity, the salt content and salt accumulation depth in soil body increased with increasing irrigation quota. Successive brackish water irrigation in the whole growth period of spring wheat induced soil salinization, and insufficient irrigation made the salt more accumulated in surface soil layer, compared with sufficient irrigation.
Yao Z.-F.,China Agricultural University |
Wang F.-J.,China Agricultural University |
Xiao R.-F.,China Agricultural University |
He C.-L.,China Water Resources Beifang Investigation Design and Research Co.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2012
Pressure fluctuations in double-suction centrifugal pumps caused by internal flow are the primary sources of operation instability. By means of pressure transducers installed in suction chamber and volute wall, fluctuating pressure signals were obtained and recorded at various operation conditions. The signals in time and frequency domains of the signals were analyzed by using the fast Fourier Transform Method. The results show that rotating frequency and some lower frequencies are dominative in suction chamber. The latter is adjacent to the 1/3 rotating frequency at the design and higher flow rates. While at partial flow rates, the magnitudes as well as the range of the lower frequencies become notably larger. Blade passage frequency dominates the pressure fluctuations in volute, of which the magnitude becomes relatively smaller when the position is far away from the volute tongue in peripheral direction. The peak-peak value of pressure fluctuation increases remarkedly as the flow rates deviate from the designed one and reaches 4~5 times higher at the partial flow rates.
Wang X.-L.,Tianjin University |
Jiang Z.-Y.,China Water Resources Beifang Investigation Design and Research Co. |
Zhou S.-S.,Tianjin University |
Zhou Z.-Y.,Tianjin University |
Zhang Z.-Q.,Tianjin University
Gongcheng Lixue/Engineering Mechanics | Year: 2011
The ice damage of diversion channel is dangerous to the hydropower station operation, even results in great life losses, so the operation mode of the ice delivery and sluicing is key to diversion-type hydropower station in winter. A 3D unsteady Eulerian two-phase model is developed. The momentum transfer term includes the drag, virtual mass, lift forces, and density difference. The results under different turning radius are as follows: When the turning radius is 200m, the water flow is steady, the water velocity distribution is homogeneous, the amount of floating ice reaches its maximum, and the ice removal efficiency is the highest. Therefore, the optimum turning radius is 200m, and the reasonable design of ice gate can ensure the smooth removal of ice and the safety operation of hydropower station. The prediction by the present model for ice removal of bend channel is confirmed by the experimental results of open channel bend reported by Blanckaert.
Jiang P.,Dongbei University of Finance and Economics |
Qin S.,Lanzhou University |
Wu J.,Lanzhou University |
Sun B.,China Water Resources Beifang Investigation Design and Research Co.
Mathematical Problems in Engineering | Year: 2015
Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term wind speed prediction is examined; the model is based on cross correlation (CC) analysis and a support vector regression (SVR) model that is coupled with brainstorm optimization (BSO) and cuckoo search (CS) algorithms, which are successfully utilized for parameter determination. The proposed hybrid models were used to forecast short-term wind speeds collected from four wind turbines located on a wind farm in China. The forecasting results demonstrate that the intelligent hybrid models outperform single models for short-term wind speed forecasting, which mainly results from the superiority of BSO and CS for parameter optimization. © 2015 Ping Jiang et al.
Yao Z.,China Agricultural University |
Wang F.,China Agricultural University |
Xiao R.,China Agricultural University |
Yang M.,The Aerospace Corporation |
He C.,China Water Resources Beifang Investigation Design and Research Co.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2015
Flow passage coating can effectively improve the resistance to wear, and reduce the hydraulic loss. However, the effect of the flow passage coating on pressure fluctuations for double suction centrifugal pumps has not been understood yet. The experiments for a centrifugal pump with and without flow passage coating were carried out. The fluctuating pressure signals were obtained and recorded at various operating conditions, then time and frequency domains of the signals were analyzed by using the Fast Fourier Transform method. The results show that the flow passage coating decreased the surface roughness, reduced the hydraulic loss and eventually increase the efficiency. However, flow passage coating had changed the pressure fluctuation characteristics. For the suction chamber, the operating range of pump stability was narrowed. And the peak to peak value of pressure fluctuation in suction chamber with coated surface may reached 2.8 times as large as that with original one, which enhanced the operating instability at partial flow rates. For the volute region, the pressure fluctuation at the monitoring location relatively closed to the volute tongue remarkably increased at the partial flow rates. While the pressure fluctuation at the monitoring location relatively far from volute tongue increased at high flow rates. The effect of flow passage coating on pressure fluctuation was not obvious on the design flow rate. To develop the synthetic benefits of flow passage coating technology and ensure the stable operation of pumps, the pump with flow passage coating should not operate at the flow rates that are derived from the design flow rate, especially at the flow rates below 75% of design flow rate. ©, 2015, Shuili Xuebao/Journal of Hydraulic Engineering. All right reserved.