Liu X.,HohaiUniversity |
Liu X.,University of Alberta |
Wang Z.-F.,HohaiUniversity |
Jin D.-Z.,HohaiUniversity |
Jin D.-Z.,Nanjing Agricultural University
Technics Technologies Education Management | Year: 2011
Quantifying and minimizing the risks associated with schedule and cost in hydropower construction are the main challenges for all parties involved. Under the impact of uncertain factors such as meteorological factor, there is a great uncertainty in the construction schedule of hydropower construction, accompanying with the occurrence of cost risk. Based on the definition of construction cost risk, this paper establishes the cost risk analysis model under fixed schedule risk probability, discusses the uncertainty and distribution of construction cost and the calculation method of crashing cost. By use of the probability theory and Monte Carlo simulation method, a scientific calculation method and procedure were worked out for construction cost under the schedule risk probability given. The 95th percentile project schedule value, its corresponding cost value, and the percentile ranking of the cost were recorded, and the conditional percentile ranking of the cost values were determined. Finally, in order to quantify the relationship existing between the percentile ranking of the cost and its corresponding cost value, the regression analysis models about them were founded and compared, and the high confidence percentile estimating values for cost and schedule were required simultaneously. Having the ability to accurately quantify this relationship enables the selection of high percentile level values for the hydropower construction cost estimate and schedule simultaneously.
Yang C.X.,HohaiUniversity |
Zheng Y.,HohaiUniversity |
Qzhou D.,HohaiUniversity |
Li X.X.,HohaiUniversity |
IOP Conference Series: Earth and Environmental Science | Year: 2012
Tubular turbines have many advantages such as large flow, high-speed, high efficiency, wide and high efficiency area, compact structure, simple layout, etc. With those advantages, tubular turbine is becoming one of the most economic and suitable types of turbines to develop low head hydraulic resources. According to the general situation of the hydropower station in the north of Jiangsu, a super low head pit turbine which head is set as about 2m is developed by the research to utilize the low head hydraulic resource.The CFD technology was used to calculate the flow field. The computing zone was meshed with unstructured gird. The whole flow passage of shaft type tubular turbine was calculated by 3-d steady turbulent numerical simulation. The detail of flowthrough the whole flowpassage was attained and the influence to the turbine's performance was analyzed by the low head runner blade's various diameters, airfoils and setting angles. The best turbine runner was obtained by considering all the methods. Meeting the station's requirements, the results show that the runner exhibits the highest performance in the efficiency, hydraulic loss and static pressure sides with 1.75m diameter, optimized airfoil and 23 degree setting angle. The developed super low head pit turbine shows highest efficiency under the design condition of 2.1m water head and 10m 3/s flow rate. GD-WS-35 turbine model test was carried out tostudy the performance of the turbine. On the basis ofmodel transformation principle,the numerical simulationresultof GD-WS-175turbine was compared with the model results. It's showed that the model test result is basically consistent with numerical simulationresult. The producing error in the numerical computation is not easy to control. The efficiency's error range is ±3%. © 2013 Published under licence by IOP Publishing Ltd.
Zhang W.,HohaiUniversity |
Li Y.,HohaiUniversity |
Wang C.,HohaiUniversity |
Wang P.,HohaiUniversity |
And 2 more authors.
Water Research | Year: 2013
The mechanisms of simultaneous photocatalytic hydrogen production and estrogenic activity (EA) removal from secondary effluent were investigated by evaluating the effects of initial dissolved oxygen (DO), organic matter, and inorganic ions on the process. The photocatalytic process was enhanced and can be divided into two phases according to the availability of DO. In aerobic phase, the humic/fulvic-like compounds in hydrophilic substances fraction were preferentially decomposed by aerobic photo-formed reactive oxygen species (i.e. O2-, h+, and OH) with generation of electron donors (i.e. formaldehyde, acetaldehyde, acetate, and formate). Approximately 41% of dissolved organic carbon and 90% of EA were reduced in the aerobic phase. In the following anoxic phase, the hydrogen production was significantly improved (apparent photonic efficiency 3.04×10-3) by the generated electron donors and accompanied with completely EA removal by the anoxic photo-formed OH. Hydrogen production was enhanced with the presence of low concentrations of HPO4 2- (below 0.1mmol/L) and HCO3 - (below 0.2mmol/L) through accelerating electrons accumulation while it was inhibited at high concentrations since the formed ion-radicals could not decompose humic/fulvic-like compounds. EA removal was inhibited by HPO4 2- and HCO3 - through scavenging h+/ OH. The presence of NO3 - (below 1mmol/L) only resulted in minor impacts since NO3 - was almost unreactive toward electronor OH in neutral conditions. © 2013 Elsevier Ltd.
PubMed | HohaiUniversity
Type: Case Reports | Journal: Ground water | Year: 2016
The characteristics of karst aquifers are difficult to be determined due to their heterogeneous physical properties and lack of hydrogeological information. In this case study, we applied two methods for a comparative analysis of storage and drainage characteristics in upstream, midstream, and downstream of Houzhai cave stream basin. In the first method, Minimum Smoothed Method (MSM) is used to determine the proportion of baseflow to the total flow (Baseflow Index, BFI). In the second method, a bicarbonate-base two-end member mixing model is used to quantify the slow flow component and fast flow component. For both methods, slow flow and quick flow are quantified at three sampling sites, which provide useful information for the analysis of storage and drainage characteristics. The results from flow separation method and hydrogeochemical analysis show a consistently increasing trend of the proportion of slow flow to total flow from the upstream to downstream which indicates that the voids of highly conductive conduits and well-connected fissures decrease along the flow paths in the Houzhai cave stream basin in southwest China. The upstream areas have a low proportion of baseflow which indicates a high drainage capacity due to high permeable conduits and well-connected fissures. The downstream areas, on the contrary, have a high proportion of baseflow which indicates a high storage capacity and slow infiltration due to the predominant presence of matrix and poorly-connected fissures. These numerical methods provide alternative ways to investigate the storage and drainage characteristics of karst aquifers where direct measurement are not available.