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Lin T.,Hohai University | Zhang J.,Nanjing Water Planning and Designing Institute Company Ltd | Chen W.,Hohai University | Sun Y.,Hohai University
Clean - Soil, Air, Water | Year: 2014

Bench-scale experiments were conducted to evaluate effects of UV radiation (UVR) on Limnoithona sinensis (Copepoda, Crustacea). Results showed that water depth, wavelength, and irradiation time significantly reduced the swimming activity of L. sinensis. The inactivation rate increased with irradiation time, and there was an inverse relation between inactivation rate and water depth. Positive phototaxis was observed in copepods exposed to visible light with wavelengths of 480 or 500nm, which caused a substantial increase in the inactivation rate when UVR was combined with visible light. Scanning electron microscopy showed that the skin of L. sinensis inactivated by UVR appeared dry and wrinkled, which was possibly due to induction of osmotic changes across cell membranes. As indicated by three-dimensional fluorescence spectra showing leakage of protoplasm to the external environment. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luo C.,Yangzhou University | Cheng L.,Yangzhou University | Liu C.,Yangzhou University | Qi W.,Nanjing Water Planning and Designing Institute Company Ltd | Shang Y.,Yangzhou University
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2015

To analyse the hydraulic performance of the mixed-flow pump with vaned diffuser in a waterjet propulsion system more accurately, CFX code is used to simulate the steady turbulent flow in the system, which consists of a pump, entry duct, water body below the vessel and nozzle, at various flow rates by means of the standard k-ε turbulence model. The hydraulic loss distribution, hydraulic performance, axial thrust and flow field features are exploited. Because the geometry of entry duct is relatively complex where its rectangular section at the inlet needs to be transformed into a circular one at the outlet, the hydraulic loss takes a maximum proportion in the entry duct, especially at a low flow rate. In that case, the proportion exceeds 90%. However, this proportion reduces with increasing flow rate, and the hydraulic loss proportions in the other components increase accordingly. The system is subject to the hydraulic instability around 0.50Qd. The high efficiency zone exists in the range of 0.76Qd and 1.10Qd. The axial thrust generated by the pump diminishes when the flow rate rises. At a small flow rate, the flow pattern in the impeller is complicated, and the spanwise vortex, radial vortex and leakage vortex are evident. Fortunately, these vortices are shrunk until disappear with increasing flow rate. ©, 2015, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved.

Zhai Y.,Hohai University | Jin Y.,Nanjing Water Planning and Designing Institute Company Ltd | Chen L.,Hohai University
Advance Journal of Food Science and Technology | Year: 2015

A well-designed subsurface drainage system with reasonable drain space and depth contributes to large ratio of desalination and high crop yield. In order to find out the optimal space and depth of subsurface drainage tubes for tomato cultivation in greenhouse salty soils in south of China, drainage treatments with different buried methods were designed, the tomato quality, yield, Irrigation Water Use Efficiency (IWUE) and surface soil electricity conductivity in the treatments were observed during 2010 to 2012 growth seasons and the principle component analysis model and projection pursuit model were used to select the treatment with best comprehensive effects. Results showed that: (1) The tomato yield was increased by 14.21 to 50.29% during the growth seasons; (2) Surface soil EC decreased significantly, although in the process of experiments, surface soil EC of some treatments showed a temporary rise; (3) Under the same buried depth, the closer arrangement of subsurface drainage tubes appeared to be more effective for the yield gaining and topsoil desalination; (4) T7 was proved to be the optimal treatment according to the calculations of projection pursuit model, the comprehensive effects of which were the best, mainly embodying in improving the tomato quality, increasing the yield and IWUE and reducing salinity in topsoil. In this study, 0.8m depth combining with 4m space was selected as the optimized layout of subsurface drainage tubes for the tomato cultivation in greenhouse salty soils of south China. © Maxwell Scientific Organization, 2015.

Zhang R.,Yangzhou University | Zhang R.,Jiangsu Surveying and Design Institute of Water Resources Co. | Li C.,Nanjing Water Planning and Designing Institute Company Ltd | Yao L.,Jiangsu Surveying and Design Institute of Water Resources Co. | Zhu H.,Yangzhou University
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2012

In order to obtain the transient hydraulic characteristics of the bulb pump unit in a pump station with VFD during startup, the essential features of low-speed synchronous startup controlled by VFD were analyzed initially. Then the moment equilibrium equation of the rotor of pump unit was established in the startup transient period. The mathematically expressing approach for the electromagnetic torque in the synchronous motor in terms of time was investigated. The resistance moments, inclusive of hydraulic resistance moment, bearing frictional moment and motor cooling fan resistance moment etc, and their mathematical expressions were clarified. Finally, the flow rate allocation and conservation between the rapid-drop gate and flap valve during the transient period were determined. Taking Huaiyin No. 3 Pumping Station as a study case, the startup transient process of the pump unit under the design condition was simulated to obtain the primary electrical and hydraulic parameters. In the simulation, the pump started running when the instant exciting current reached 0.63 times its design value and the frequency was about 6.5 Hz, causing a 15 s lag delay. As a result, a best match was obtained between the motor rotational speed frequency and the lag time for opening the rapid-drop gate. At the design condition, when the rotational speed of the synchronous motor is linearly increased from 0 to 125 r/min in 100 s interval, the optimal lag time is 70 s for opening the rapid-drop gate.

Zuo D.-J.,Tianjin Research Institute for Water Transport Engineering | Zuo D.-J.,Hohai University | Chen L.,Hohai University | Tian Z.-W.,Nanjing Water Planning and Designing Institute Company Ltd | Qi C.-G.,Ningbo University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2015

Based on a liquefied natural gas terminal wharf project in Tianjin, the finite element software ABAQUS is used to study the mechanical characteristics of pile groups of wharf foundation under lateral and vertical cyclic loadings, and the influence of cyclic period of lateral and vertical loadings is discussed. The results indicate that under the lateral and vertical cyclic loadings, the stress of piles redistributes, the shaft force of piles increases, and the side resistance decreases. The increase amplitude of shaft force row piles is the largest. The range of side resistance is mainly concentrated in the area of more than 1/3 of pile length. The cyclic period has great influence on the stress redistribution: with change of the cyclic period, load distribution of piles adjustes gradually, the shaft forces of front and back row piles increase, and the shaft forces and side resistances of the middle row piles decrease. When the cyclic period reaches a certain value, the shaft forces and side resistances of piles no longer change and tend to a steady state. ©, 2015, Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering. All right reserved.

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