Journal of Hydroelectric Engineering

水力发电学报

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2015 Vol. 34, No. 2 Published: 2015-02-25

	1	Calculate Sherman unit hydrograph by stepwise filter optimization method
		ZHU Chengtao, WANG Xiaofeng, DAI Xiaolong
		Since 1932 when Sherman put forth a unit hydrograph concept, Sherman unit hydrograph has been a basic hydrological method for solution of complex runoff concentration. The authors analyze the current methods of unit hydrograph calculation and their problems, and present a stepwise filter optimization method. This paper gives objective function and tconstraint conditions for this method, elaborates the theory of moving average filter and moving polynomial filter, and demonstrates a procedure for its calculation of unit hydrograph. Its application to calculation of Sherman unit hydrographs for different river basins has achieved satisfactory results.
		2015 Vol. 34 (2): 1-6 [Abstract] ( 220 ) PDF (590 KB) ( 456 )

	7	Improved support vector machine regression model and its application to annual runoff forecasting
		CUI Dongwen, JIN Bo
		This paper presents an annual runoff forecasting model using the heuristic algorithms of PSO-SVR and GA-SVR to overcome the practical difficulties in selection of the penalty factor and kernel parameters of support vector machines for regression (SVR) and to reduce the influence of selection on model performance, including a case study of the Luoque station in Yunnan. This method first determines the input vector by selecting the impact factor of annual runoff using the SPSS code, and then constructs PSO-SVR and GA-SVR-multivariate models of annual runoff forecasting, based on the basic principles of particle swarm optimization (PSO) and genetic algorithm (GA), using the penalty factor and nuclear function parameters of PSO and GA optimization SVR. For comparison, a combined GS-SVR model is constructed with the algorithms of grid search (GS) and cross-validation (CV). Application of these two multivariate models to one practical example shows that the predictions of a runoff series of 16 years by PSO-SVR and GA-SVR (averaging five random predictions) have average relative errors of 2.53% and 2.79%, maximum relative error of 7.11% and 6.64%, and average absolute errors of 0.14 and 0.15, respectively. Their prediction accuracy and generalization ability are better than GS-SVR model, showing that PSO and GA can optimize the penalty factor of SVR and its nuclear function parameters. In addition, the two models are superior in robustness and performance. Relatively, PSO-SVR model is slightly better than GA-SVR.
		2015 Vol. 34 (2): 7-14 [Abstract] ( 177 ) PDF (594 KB) ( 767 )

	15	Analysis on detection and attribution of runoff change in Kuye river basin
		BAI Le, LI Huai-en, HE Hongmou
		This study is to provide an identifiable ground for development and utilization of water resources in the Kuye River basin under the direct impact of abnormal climate changes and human activities. According to trend analysis on the annual runoff series at the Wenjiachuan hydrologic station in the basin from 1954 through 2010, MK-P method and Pettitt test were used to detect the abrupt points in this series, and the contribution ratios of rainfall, potential evaporation, and human activities on the runoff were calculated by the method of slope change ratio of cumulative quantity (SCRCQ). Results show that the series has significant decreasing trends and mutation features with two abrupt points that occurred in 1979 and 1996. Relative to the reference period 1954—1979, the impact proportions of annual precipitation, annual potential evaporation, and human activities on runoff were 29.2%, -3.6%, and 74.4% respectively in the period 1980—1996 of low human activity intensity, and 20.6%, -1.5%, and 80.9% in 1997—2010 of high intensity. If compared with the period of low human activity intensity, the impact proportions were 11.9%, -0.2%, and 88.0%. Large-scale water and soil conservation measures and high-intensity coal mining have produced significant effects on the mutations in the Kuye River runoff.
		2015 Vol. 34 (2): 15-22 [Abstract] ( 168 ) PDF (721 KB) ( 507 )

	23	Dynamic control of flood limited water level for cascade reservoirs
		ZHOU Yanlai, GUO Shenglian, et al
		This paper presents a method for real-time dynamic control of flood limited water level for the Qing River cascade reservoirs. In this method, we developed a weather forecasting model for forecasting the flood process in future three days, then an optimal-operation-curve model using a genetic algorithm for optimization of long-term reservoir operation and a binary Copula-SAR stochastic model to simulate the long-term behaviors of runoff. Finally, a real-time optimal operation model was constructed using an aggregation-disaggregation approach to dynamic control flood limited water level for cascade reservoirs and considering the rules for coupling long-term and short-term operations, and an optimal algorithm POA was adopted to solve the model. The results show that the real-time dynamic control with long-term operation rules can generate extra power outputs of 0.059 and 0.314 billion kW·h (increases by 6.2% and 45.1%) relative to those without coupling long-term operation rules and in design operation, respectively.
		2015 Vol. 34 (2): 23-30 [Abstract] ( 207 ) PDF (786 KB) ( 535 )

	31	Application of improved ant colony algorithm to optimal dispatching of reservoir group water supply
		IU Honghong, WANG Ni, XIE Jiancang, et al
		A mathematical model with a penalty function was developed to solve optimization problems with multiple constraints in the dispatching of reservoir group water supply by using an improved ant colony algorithm, focusing on the method of improvement. This improved algorithm is featured with self-adaptive adjustment in pheromone evaluation coefficient, information quantity, and transition probability, and it can overcome the defects of traditional ant colony algorithm in slow convergence and local-extremum trapping. Its application to the three reservoirs on the Hei River achieved optimal scheduling schemes better than traditional ant colony algorithm. The improved algorithm is better in computational efficiency, optimization results, convergence, and it provides a new approach to optimization of reservoir group water supply dispatching.
		2015 Vol. 34 (2): 31-36 [Abstract] ( 173 ) PDF (284 KB) ( 646 )

	37	Derivation of optimal operating rules for cascade hydropower stations based on projection pursuit regression model
		WANG Jinlong, HUANG Weibin, et al
		To better understand complicated nonlinear relationships between the input and output variables of optimal operation for cascade hydropower stations, this study develops a projection pursuit regression model using a ridge function of nonlinear Hermite polynomials and optimizes the operation with a real accelerating genetic algorithm. This model combines correlation analysis with multivariate stepwise regression analysis method to select the independent variables of dispatching function, obtaining a better way to determine the dispatching factors in formulating optimal operation rules for the cascade stations. Application of the model to one example shows that its fitting accuracy and robustness in solving dispatching function are superior to BP artificial neural network model.
		2015 Vol. 34 (2): 37-43 [Abstract] ( 176 ) PDF (451 KB) ( 462 )

	44	Evaluation method on hard-regulated and utilized volume of hyper-concentration floodwater in flood season
		LI Xungui, WEI Xia, et al
		Evaluation on the hard-regulated and utilized volume of floodwater (HCUVF) in flood season for hyper-concentration rivers is a key issue in hydrology and water resources, but at precent the understandings of its connotations and properties and the existing evaluation methods are very limited. This work takes a case study of the Bajiazui reservoir on Jinghe River. With consideration of the operation of reservoir flood control and the sediment transport limitation on utilization of watershed water resources, and in view of water quantity and quality, HCUVF is divided into two portions, a hard-regulated volume and a hard-utilized volume. The two portions are calculated with an optimal operation model of reservoir flood control and a maximum grade approach, respectively. Results show that the hard-regulated volume much depends on the inflow flood events of reservoir. In the flood season of 1988, four such events occurred with a total volume of 4.56 million cubic meters (mcm). For the second portion, the coefficients of surplus floodwater in flood season can be determined by using the optimization results of reservoir operation and the corresponding sediment concentrations in the river flow, and its volume of 103.80 mcm was estimated. Summing up the two figures gives a total HCUVF of 108.36 mcm for the flood season of 1988. Thus, the presented method is reliable and provides an insight into development and utilization of floodwater resources and study of flood disaster risk.
		2015 Vol. 34 (2): 44-49 [Abstract] ( 196 ) PDF (411 KB) ( 274 )

	50	Assessment model of terrestrial ecological risks for Nuozhadu reservoir
		WANG Liping, ZHANG Pu, et al
		Assessment on ecological risks of large reservoirs is an important part of eco-environmental protection and improvement, but few of its studies have been reported. This paper constructs a multi-level risk receptor or an evaluation index system of multiple risk sources that describes the complicated relationships and mechanism in ecological risks, on the basis of identifying these sources and receptor of the valley area of terrestrial ecosystems in a case study of the Nuozhadu reservoir on the Lancang River. We followed the thoughts of relative risk model (RRM) and developed a multi-level fuzzy model of comprehensive evaluation to handle the variety of risk evaluation indicators and measures, the difficulties in quantification of some indicators, and the fuzziness in human cognition of ecological system. Results show that this model can give a quantitative score of fuzzy evaluation on the ecological risks for each receptor. By comparative analysis, they provide crucial information to the scheme design of eco-environmental improvement for the reservoir area. This contributes to gradual slowdown of the negative ecological effect, further promotion of social, economic, ecological and environmental benefits, and sustainable utilization of the reservoir area, making beneficial attempts for study on ecological risk assessment of large reservoirs.
		2015 Vol. 34 (2): 50-56 [Abstract] ( 153 ) PDF (787 KB) ( 349 )

	57	Application of variable fuzzy set method based on entropy weight to classified real-time flood forecasting
		WU Hengqing, HUANG Qiang, et al
		This paper applies a variable fuzzy set method based on entropy weight to construction of a framework of classified real-time flood forecasting using the concepts of clustering and classification. Fuzzy clustering was used to classify historical floods based on the flood antecedent impact factors and time-varying rainfall information. In the present study, this conceptual hydrological model was calibrated for each type of flood. In application, a fuzzy diagnosis model was used to identify the types of floods in future by using the flood information obtained. Results show that the classified framework gives a fast and accurate diagnosis of the type of flood and significantly improves the accuracy of flood forecasting.
		2015 Vol. 34 (2): 57-63 [Abstract] ( 197 ) PDF (424 KB) ( 464 )

	64	Three-dimensional numerical simulation of internal flow in gill-sheet separation device under muddy water of different sediment concentrations
		TAO Hongfei, QIU Xiuyun, et al
		Three-dimensional numerical simulations were conducted for the water-sediment two-phase flow in a gill-sheet separation device with a laminar model and an Euler particle multiphase flow model solved by the phase-coupled SIMPLE (PC-SIMPLE) algorithm to study the effect of sediment concentration of muddy water on velocity field and characteristics of sediment distribution. The results show that sediment concentration has no effect on velocity distribution of the flow in this device but a higher concentration leads to a greater average velocity of the flow and a higher average concentration. A lower concentration of muddy water improves the effect of water-sediment separation. In the height direction of the device,water-sediment separation is faster at the locations closer to the top of the device, and at these locations it is relatively easier to obtain clean water.
		2015 Vol. 34 (2): 64-71 [Abstract] ( 114 ) PDF (1042 KB) ( 345 )

	72	Study on optimal reinforcement of bridges and culverts based on HEC-RAS simulation model
		TAN Yuxin, WU Yongxin
		Reinforcement of bridges and culverts cross a river often produces a certain effect on its flood safety, and a demonstration of flood safety at the design stage of reinforcement becomes an indispensable part of the reinforcement project. This paper describes three alternative schemes for the reinforcement of Yusha bridge cross the Haiguan channel in Haikou city, and presents a one-dimensional hydraulic model for this project developed on the platform of HEC-RAS simulation model with an analysis on the impact of these schemes on the water level in the channel and the stability of river regime. We have obtained results of intuitive simulation for the flood safety of bridges and culverts, which provides useful information for the Yusha bridge reinforcement and other similar projects.
		2015 Vol. 34 (2): 72-76 [Abstract] ( 131 ) PDF (620 KB) ( 405 )

	77	Study on hydraulic characteristics of contraction-expansion energy dissipater based on numerical simulation
		AI Wanzheng
		Energy dissipater with abruptly-contracted and expanded cross sections, featured with high energy dissipation efficiency and convenient construction, has a broad application prospect in China. It is significant to explore and understand its hydraulic characteristics. This paper presents a study on the relationships of energy loss coefficient versus geometry parameters for this type of energy dissipaters, focusing on a comparison of flows in the orifice plate and tunnel plug dissipaters. Results indicate that the energy dissipation coefficients of plug and orifice both decrease with contraction ratio and that under a fixed contraction ratio, the energy loss coefficient of orifice plate decrease with its thickness while that of plug varies little. Under a fixed contraction ratio, the energy dissipation efficiency of orifice plate is higher than that of plug dissipater.
		2015 Vol. 34 (2): 77-84 [Abstract] ( 170 ) PDF (933 KB) ( 354 )

	85	Application of curved slit-type flip bucket at Maerdang hydropower station
		WANG Rui, LIU Hansheng, et al
		Curved slit-type flip bucket is a typical trajectory energy dissipator invented in China. This article presents a comparison of this slit-bucket with a traditional straight-wall slit-type flip bucket, including an analysis on their structures and forces. Results show that it is characterized by lower sidewall height, higher energy dissipation efficiency, weaker pressure pulsation, and better structure stability. A hydraulic model has been tested for the design of Maerdang hydropower station that is featured with high water head, great flow velocity, shallow downstream tail water depth, and centralized arrangement of flood discharge structures. Using the data of scale model tests, we made a comparative analysis on the curved slit-bucket, tongue-type flip bucket, oblique flip bucket, and straight-wall slit-bucket. This analysis confirms that curved slit-bucket has advantages in appropriate nappe-plunging location, full diffusion of nappes longitudinally and transversely, shallower scour pit, and less influence of riverbed deposition on the tail water of power generation. Thus, it is a suitable energy dissipator for Maerdang hydropower station of dam height over 200m.
		2015 Vol. 34 (2): 85-90 [Abstract] ( 191 ) PDF (462 KB) ( 345 )

	91	Numerical simulation of sediment management for pumped storage power station
		WEI Hongyan, XU Qiumeng, et al
		Pumped storage power station plays an irreplaceable role in improving the security, stability and reliability of power system operation, while sediment passing through the turbine is a key factor that restricts the safe operation of power station. This study adopts virtual confluence nodes to simulate complex flow pattern near the inlet and outlet of power station, and integrates the calculations of the upper and lower reservoirs and the sediment passing through the turbine. Then, a numerical model of flow and non-uniform total sediment control is developed for pumped storage power station in daily or weekly operation mode. This model is verified by using both field observation data and physical model tests. In a case study, the effect of reservoir stage on reservoir sedimentation and turbine sediment concentration is analyzed.
		2015 Vol. 34 (2): 91-97 [Abstract] ( 156 ) PDF (1882 KB) ( 592 )

	98	Analysis on hydraulic characteristics of hydrocyclone in horizontal straight pipeline under operation
		YANG Xiaoni, LI Yongye, et al
		To understand the specific role of hydrocyclone in hydraulic transportation, a horizontal straight pipeline was used to experimentally test the hydraulic characteristics of hydrocyclone in its motion process. Model test and theoretical analysis were used in this study to examine the behaviors of hydrocyclone with different widths and different angles of guide vanes. It is shown that a larger angle of guide vanes leads to lower axial velocity, greater circumferential velocity, and greater absolute value of radial velocity at test section. The wider the guide vanes, the smaller the axial velocity and the greater the circumferential velocity at test section, and the greater the radial velocity in tube core. When the flow rate is increased, the axial velocity at test section increases, but the trends of changes in circumferential and radial velocities depend on the angle of guide vanes.
		2015 Vol. 34 (2): 98-102 [Abstract] ( 183 ) PDF (1285 KB) ( 387 )

	103	Study on variation trends of flow diversion from Jingjiang River to Dongting Lake
		ZHU Lingling, CHEN Jianchi,, et al
		This paper analyzes the changes in flow diversion from the Jingjiang River to the Dongting Lake in the recent sixty years, and demonstrates the causes of these changes: extra-large floods, construction of lower Jingjiang cut-off project, and operation of the Gezhouba reservoir and Three Gorges reservoir. The changes in the diverted flows through the Jingjiang Three Outlets showed significantly periodical behaviors, and at each stage of such periods the diverted flows were dominated by several trend-adjusting periods and equilibrium-adjusting periods. A deeper exploration on the causes and their effect on the adjustment of flow diversion at the outlets reveals that the direct cause for reduction in the diverted flows was the decrease in water level difference between the Yangtze mainstream and the Three Outlets channels before the mid 80’s, and then it was shifted to the flow reduction in the middle Yangtze. The variation trends of flow diversion from Jingjiang to Dongting were predicted by using changes in control factors at different stages.
		2015 Vol. 34 (2): 103-111 [Abstract] ( 154 ) PDF (2068 KB) ( 323 )

	112	Study on application of slit-bucket energy dissipater to multi-tunnel combined spillways
		ZHANG Yingying, WANG Junxing
		The Changheba hydropower station is typical of high head and large capacity of multi-tunnel combined discharge with flip-bucket energy dissipaters that require a great capacity of the downstream river channel in energy dissipation and anti-scour. Large-scale hydraulic model tests have been conducted to solve the problems of insufficient energy dissipation and poor condition of nappes plunging into river at the initial stage. For slit-bucket and constant-width flip bucket, we compared their effects of energy dissipation and anti-scour on the second spillway in the conditions of individual operation and combined operation, and verified the advantages of combined slit-bucket and flip bucket for multi-tunnel combined operation. The results are useful for design of similar energy dissipation and anti-scour structures.
		2015 Vol. 34 (2): 112-117 [Abstract] ( 187 ) PDF (817 KB) ( 405 )

	118	Hydrodynamic analysis of array-type device of wave energy generation
		?HE Guangyu, YANG Shaohui, et al
		This paper presents a new array-type device of wave energy generation and describes its working principle.A simulation model for this device was developed and its parameters and finite element mesh were calculated by the method of AQWA. Using this model, we analyzed the RAO parameters of frequency responses for a single float of different sizes and drafts and the characteristics of whole float array under different angles of wave incidence. The results show that for a single float, when its draft is in the range 1.2-1.4m and its diameter 2.8m, the RAO parameter is maximized. And for the float array, a greater average amplitude of relatively higher efficiency in capture of wave energy can be achieved at an incidence angle of 22.5° with a small variation in the amplitudes of different floats.
		2015 Vol. 34 (2): 118-124 [Abstract] ( 167 ) PDF (515 KB) ( 1045 )

	125	Study on cavitation damages of supplementary dissipater under low-Froude-number flows
		YANG Fan, WANG Junxing, et al
		Cavitation damage of supplementary dissipater is a key problem of hydraulic structures that has drawn much attention and study efforts. This paper focuses on an analysis of the experimental tests on cavitation and cavitation damages of supplementary dissipaters in common use. We describe two measures against cavitation damage: a combined energy dissipater of stilling basin, incomplete flaring gate piers, and baffle piers; baffle piers with smooth rounded edges. The results show that this combined dissipator can reduce the flow velocity near the bottom and the forces on baffle piers, increase cavitation number of the baffle piers, and improve the rate of energy dissipation effectively. If its edges are rounded appropriately, a baffle pier will has a lower incipient cativition number, the turbulent motions behind it are weakened, and its cavitation number is increased, improving its resistance against flow cavition.
		2015 Vol. 34 (2): 125-129 [Abstract] ( 165 ) PDF (605 KB) ( 542 )

	130	Numerical study on characteristics of dual buoy for wave energy conversion device
		SONG Ruiyin, CAI Bingqing, et al
		This paper presents a dual buoy wave energy device composed of a big boat buoy and a small gyro-shape buoy, focusing on an analysis of the gyro-shape buoy using numerical simulation method. A simulation model was developed to calculate the stress and deformation of gyro-shape buoys with different tip radii under water flows in horizontal and vertical directions, and the adaptability of the buoys to waves and their power and efficiency characteristics were analyzed. Using the simulations, we optimized the key scale parameters that control the stress and deformation of the buoys. The results indicate that the gyro-shape buoy is applicable to testing platform for wave energy capture.
		2015 Vol. 34 (2): 130-135 [Abstract] ( 193 ) PDF (792 KB) ( 679 )

	136	Study on bearing behavior of prestressed composite linings with cushion layer for water conveyance shield tunnel
		Shengrong,YANG Fan,, et al
		The force characteristics of prestressed composite linings with a cushion layer for water conveyance shield tunnel are studied. To simulate this structure, a three-dimensional finite-element model of whole structure is developed on a platform of the FEM code ANSYS and applied to the design of the Yellow River-crossing tunnel for the middle route project of south-to-north water diversion. For two cases of the composite structure with or without a cushion layer, stress distributions in the inner lining and outer lining are compared, and force transmission mechanism between the two linings are analyzed for different stiffness of the cushion. And the effect of a change in cushion stiffness on the hoop stress in the linings is examined. The results reveal that for the structure of prestressed composite linings, if a cushion layer is added appropriately, its prestressed tension can be in full use and the design objective for the inner or outer lining to work independently in load bearing can be achieved. This improves the distributions of stress in the linings and makes the outer lining bear greater compressive stress, hence improving the overall safety of lining structure. And a decrease in cushion stiffness results in a lower ratio of water pressure transfer from the inner to outer lining and a better effect of prestressed tension in the inner lining. Thus, the composite structure with a cushion layer is superior in stress distribution, waterproof performance, and overall structural safety for a water conveyance shield tunnel of high internal pressure and great buried depth in soft soil foundation.
		2015 Vol. 34 (2): 136-143 [Abstract] ( 167 ) PDF (621 KB) ( 543 )

	144	Reliability analysis of the tunnel liner pre-stressed with circumferential un-bonded tendons based on the monitoring data
		WANG Xiaozhe, KANG Jingfu, et al
		Compared with the concrete liner pre-stressed with circumferential bonded tendons, the tunnel liner pre-stressed with circumferential un-bonded tendons has many outstanding advantages, but the reliability restrict its general application. Stress state variation of tendon is one of the important parameters to evaluate the reliability of this type of liner structure. Based on the long-term monitoring data of tendon dynamometers in Xiao Langdi pre-stressed sediment tunnels, the influences of ambient temperature and water head on the tendon stress were analyzed. The results show that the variation of temperature has a significant effect to the tendon stress, while the variation of water head has a little impact. Xiao Langdi pre-stressed sediment tunnels has been safely served for more than 10 years and experienced the highest design water head, the prestress in the tendons is stable at all times, no fracture or relaxation of un-bonded steel strands was observed. The experience of Xiao Langdi sediment tunnels shows that the anchorage of un-bonded tendons is reliable and a safe operation can be realized for the tunnel concrete liner pre-stressed with circumferential un-bonded tendons.
		2015 Vol. 34 (2): 144-148 [Abstract] ( 146 ) PDF (383 KB) ( 330 )

	149	Dispersivity identification of clayey soil and its mechanism
		CHEN Hua, FAN Henghui, et al
		Dispersive soil wetted in water has dispersivity and likely to cause destruction of dams and other hydraulic structures. In this work, the dispersivity of clayey soil at the site of Xinjiang Akedala diversion channel has been studied, using pinhole test, crumb test, double hydrometer test, pore water soluble salt cation test, and the test of exchangeable sodium ions percentage, with comparison with an empirical equation for evaluating dispersivity of cohesive soil. The results show that by the five test methods all the six soil samples are transitional type while by the empirical equation five samples are transitional and one is dispersive. The two methods give similar identification results, so it is concluded that all the six samples are transitional soils. These soil samples contain a large amount of sodium ions, have rather high pH values, indicate strongly alkaline, which could promote dispersivity. Their high contents of clay and organic matter, however, lower their dispersivity so that they show transitional characteristics.
		2015 Vol. 34 (2): 149-155 [Abstract] ( 151 ) PDF (2905 KB) ( 346 )

	156	Monitoring and deformation mechanism analysis on rock-bolted crane girders in large underground powerhouse in high geo-stress area
		DONG Zhihong, DING Xiuli, et al
		Safety and mechanical characteristics of rock-bolted crane girders are important to construction of large underground powerhouses. For the underground powerhouse in the Jinping-I hydropower station located in a high geo stress area, mechanical characteristics of its bolts and attachment of its two crane girders to the surrounding rock are analyzed with safety monitoring at its excavation stage and a stage of 2 years later, and safety of its rock-bolted crane girders is evaluated. The results indicate that a larger deformation and deep relaxation of the surrounding rock could be caused by excavation and unloading of high geo-stress. And the stresses in the girder bolts that are generally at a high level, take a long time (roughly one year after the excavation) to reach stability. All the bolt stresses are below the yield strength of steel, and most of the joint openings between the girders and their surrounding rock are less than 5mm, with a maximum of 9.9mm.
		2015 Vol. 34 (2): 156-163 [Abstract] ( 211 ) PDF (816 KB) ( 372 )

	164	Dual evaluation on rolling compaction quality of rock-fill dam based on real-time monitoring
		WANG Xiaoling, ZHOU Long, et al
		Traditional method uses randomly-sampled dry density to evaluate dam rolling compaction quality, but it cannot reflect the real quality of rolling compaction. To improve the evaluation, a dual evaluation model combining the dry density method with a reliability theory for dry density parameter analysis on the platform of a construction quality real-time monitoring system is developed, and a corresponding implementation procedure is established for the evaluation. In application of this dual method to one reservoir construction project in Henan province, variability of dry density and its influencing factors were obtained via reliability and sensitivity analysis on its parameters. It has been shown that the dual evaluation based on real-time monitoring improves the reliability of evaluation and provides a technical support to dam rolling compaction quality control.
		2015 Vol. 34 (2): 164-170 [Abstract] ( 184 ) PDF (790 KB) ( 302 )

	171	Discussion on end-surface cavitation of Francis runner
		LI Renfei
		This paper describes the end-surface cavitation of a Francis runner, analyzes the cause for this type of cavitation, and suggests some precautions. A brief discussion on the similarity between prototype and model turbines is given.
		2015 Vol. 34 (2): 171-174 [Abstract] ( 166 ) PDF (482 KB) ( 340 )

	175	Numerical analysis on pressure fluctuations of time-varying turbulent flow in tubular pumping system with S-shaped shaft extension
		YANG Fan, LIU Chao, et al
		Numerical simulations of three-dimensional unsteady flows were carried out to investigate pressure fluctuations in the passages of a tubular pump system with S-shaped shaft extension in different operating conditions by using the code CFX and comparing with experiments on scale model. Pressure fluctuations at 21 locations of measurement in inlet and outlet passages were obtained and analyzed in time and frequency domains for three typical working conditions of different flow rates. At the exit of inlet passage, the pressure fluctuations show a frequency dominated by the rotation speed of impeller and the blade numbers, and their amplitudes decrease gradually from wall to hub. And these amplitudes decrease with flow coefficient in the range from 0.368 to 0.552. The amplitude of average pressure coefficient at the inlet of elbow tube that is one part of outlet passage, is very close to that in middle part of outlet passage, with a difference less than 0.0005. The fluctuating amplitudes in outlet passage are smaller than those at the exit of inlet passage. Under influence of the circulation at guide vane outlet, the dominant frequencies at different locations of measurements in a fixed working condition vary in a great extent, and those at a fixed location vary slightly with flow rate.
		2015 Vol. 34 (2): 175-180 [Abstract] ( 170 ) PDF (2661 KB) ( 327 )

	181	Evaluation on benefits of construction diversion under upstream flow control
		CHEN Shu, HU Zhigen
		Upstream flow control is an effective way to allocate downstream diversion risk in construction of cascade hydropower stations. Aiming at evaluation on the benefit of upstream flow control measure, this study systematically examines the generation benefit of upstream stations and the downstream stations under construction influenced by operation transformation in these upstream stations, focusing on the upstream stations and the downstream construction diversion. We explore the impact of flow control on diversion standards, construction progress, and flood safety, from a perspective of the construction diversion system and by comparison with that in free discharge condition. With consideration of all these effects, comprehensive benefits of the upstream flow control measure are calculated, and economic feasibility of a diversion risk distribution method with upstream flow control is quantitatively evaluated according to cost and benefit by taking loss in power generation as costs of flow control and selecting benefit-cost ratio as evaluation criteria. Anumerical example of risk analysis shows that the method is feasible and effective.
		2015 Vol. 34 (2): 181-188 [Abstract] ( 142 ) PDF (340 KB) ( 387 )

	189	Study on peaking capacity of cascade hydropower stations under reservoir anti-regulation
		LI Jidong, HUANG Weibin,et al
		A calculation model for hydro plant peaking capacity under reservoir anti-regulation was developed on the basis of previous assessment criteria of the peaking capacity to provide a guide for peaking operation of yearly regulation reservoirs and higher generation benefits under time-of-use (TOU) power price. In application of this model to the cascade hydro plants on Blackwater River, the peaking capacity of the Maoergai hydro plant was evaluated in the conditions of implementing an anti-regulation at the Seergu hydro plant and a second anti-regulation at the Liuping hydro plant. This simulation indicates that the anti-regulation scheme efficiently improves utilization of water power resource and hydro plant benefits and the model proves to be reasonable and applicable.
		2015 Vol. 34 (2): 189-194 [Abstract] ( 131 ) PDF (248 KB) ( 357 )

	195	Discussion on advances in power generation equipment and technology for marine renewable energy and its issues
		Lü Chao, LIU Shuang, et al
		This paper aims at better understanding of the existing status and developing trends in capture and conversion of renewable ocean energy and in use of its equipment and technology, and at promotion of the advances in technology and multilateral collaboration. We presents a summary on the technology and equipment in developing tidal energy, wave energy, and other renewable ocean energy in the world, based on the 2012 international renewable ocean energy conference and the 2013 renewable ocean energy annual conference held in China. On this basis, the common issues in the capture, conversion, and application technology of renewable ocean energy are discussed.
		2015 Vol. 34 (2): 195-198 [Abstract] ( 146 ) PDF (195 KB) ( 934 )

	199	AHP-based schedule compression method for network planning
		WANG Renchao, CHEN Jianyou, et al
		Schedule compression is commonly needed in construction management. Currently, a wide range of methods for schedule compression have been developed in the literature. Almost all these methods consider only cost in the process of determining optimal sequence for activities. But in fact, other factors beyond cost in schedule compression, such as resource availability, risk, and complexity, should have been attributed to the limited use of existing methods. This paper presents a new method for schedule compression of construction projects using an analytical hierarchy process (AHP). This method adopts a multi-objective decision environment in which activities are queued for crashing based on the preferred coefficient calculated by considering resource, risk, and cost. Finally, an example is analyzed to demonstrate the specific optimization procedure. In comparison with the traditional methods, a more objective, comprehensive and accurate preferred coefficient can be achieved, which gives decision makers better optimization solutions to meet the actual needs.
		2015 Vol. 34 (2): 199-206 [Abstract] ( 162 ) PDF (297 KB) ( 378 )