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Activation of fly ashes by the high temperature and high alkalinity in ASR tests

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Science china(Technological Sciences) 2011年第S1期54卷 28-32页

作者： CAI YueBo ,DING JianTong & BAI Yin State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering,Nanjing hydraulic research institute,Nanjing 210029,china 1. State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering Nanjing Hydraulic Research Institute Nanjing 210029 China

High temperature and high alkalinity are typical testing conditions to accelerate the appraisal process of the suppressing effect of fly ashes on alkali silica reaction(ASR),but the reaction mechanism of fly ashes would be quite different under such conditions compared to the normal condition of temperature and *** make a reasonable analysis of the suppressing effect of fly ashes,13 types of fly ashes were tested in this paper by both the accelerated mortar bar test method and the 60°C accelerated concrete prism test *** results showed that the effect of fly ashes would be magnified under the condition of high temperature and high *** XRD analysis showed that all the phases of fly ash could react with the hot alkaline solution except for mullite and a small amount of *** ash could be significantly activated by the 80°C 1 mol/L NaOH solution,and form mainly C-S-H phase and P type zeolite,but its effect on inhibiting ASR was exaggerated *** to the mortar strength test and the ASR suppressing test results,C-S-H phase contributed to mortar strength,but its amount did not decide the ASR suppressing effect of fly ash.

关键词： fly ash Alkali silica reaction Activation

Delayed response model for bankfull discharge predictions in the yellow river

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International Journal of Sediment research 2011年第4期26卷 445-459页

作者： Baosheng WU and Lingyun LI 1 Prof.,State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,china, 2 Ph.D.and research hydraulic Engineer,Changjing river Scientific research institute,Wuhan 430010,china [a] Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China [b] Ph.D. and research hydraulic Engineer Changjing River Scientific Research Institute Wuhan 430010 China

Delayed response means that channels cannot achieve a new equilibrium state immediately following disruption;the channel requires a response time or relaxation time to reach *** follows that the morphological state of fluvial system represents the cumulative effects of all previous disturbances and environmental conditions.A unique feature of the delayed response model for bankfull discharge is that the model is capable of representing the cumulative effects of all previous flow conditions when applied to predict the path/trajectories of bankfull discharge in response to altered flow *** this paper,the delayed response model was modified by readjusting the weight for the initial boundary conditions and introducing a variableβwith respect to *** modified model was then applied to the bankfull discharge calculations for three selected river reaches of the yellow river,with each reach having different geomorphic settings and constraints. Results indicated that the modified model can predict accurately the bankfull discharge variation in response to changes in flow discharge and sediment load conditions that have been dramatically altered in the *** also demonstrated the strong dependence of current bankfull discharge on the previous years’ flow conditions,with the relaxation time varied from 2 to 14 years,meaning that the bankfull discharge was not only affected by the flow discharge and sediment load in the current year,but also by those in previous 1 to 13 ***,the relaxation time of bankfull discharge adjustment was inversely proportional to the long-term average suspended sediment concentrations,and this may be explained by fact that high sediment concentrations may have a high potential to perform geomorphic work and there is more sediment readily available to shape the channel boundary and geometry.

关键词： yellow river Bankfull discharge Delayed response Flow discharge Sediment load Relaxation time

Numerical application of k-ε turbulence model to the flow over a backward-facing step

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Science china(Technological Sciences) 2010年第10期53卷 2817-2825页

作者： DING DaoYang1 & WU ShiQiang1,2 1 Nanjing hydraulic research institute, Nanjing 210029, china 2 State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering, Nanjing hydraulic research institute, Nanjing 210029, china Nanjing hydraulic research institute Nanjing China State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering Nanjing Hydraulic Research Institute Nanjing China

A model that uses the operator splitting technique based on Eulerian-Lagrangian method and embeds the k-ε turbulence mode is developed. The model is used to simulate a two dimensional flow over a backward-facing step with triangular mesh discrete flow field. The convection operator is solved with the characteristic method and the diffusion operator and pressure-Poisson equation are solved by finite element method. The results from the example showed that numerical results are well agreed with the experimental data,and that the method can be adapted to simulate complex turbulent flow with strong non-linear convection. The treatment of boundary conditions is also studied in the paper.

关键词： turbulence model the flow over a backward-facing step numerical method

Effect of Wave Groups on Wave Run-up

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china Ocean Engineering 1992年第1期7卷 79-86页

作者： Zhou Jiabao and Zhang Jiachang Senior Engineer, river and Harbour Department, Nanjing hydraulic research institute, Nanjing

-The effect of wave group on wave run-up on a slope dike is mainly discussed in this paper. Two simulating methods of wave group and their applications in laboratory are introduced. Synthesizing the research results of wave run-up on a slope dike, the effect of wave group on wave run-up on a slope dike in coastal protection engineering is studied as the main point.

关键词： wave group run-up slope dike coastal protection engineering

Overtopping Discharge of Wind-Waves on Simple Slope Dikes

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china Ocean Engineering 1991年第4期6卷 419-428页

作者： Yu Kuang-ming , Zhang Jiachang and Zhou Jiabao Professor, Senior Engineer, The river and Harbour Department, Nanjing hydraulic research institute,Nanjing Senior Engineer, The river and Harbour Department, Nanjing hydraulic research institute, Nanjing

An empirical formula for estimating the overtopping discharge of wind-waves on a smooth-impermeable-simple slope dyke is derived through model tests in this paper, it can be adopted by related design departments in th... 详细信息

关键词： Overtopping discharge design wave check wave wind-waves slope dike

A new learning statistic for adaptive filter based on predicted residuals

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Progress in Natural Science:Materials International 2006年第8期16卷 833-837页

作者： YANG Yuanxi and GAO Weiguang (Xi'an research institute of Surveying and Mapping, Xi'an710054, china institute of Surveying and Mapping, University of Information Engineering, zhengzhou 450052, china) [a]Xi' an research institute of Surveying and Mapping Xi' an China [b]institute of Surveying Mapping University of Information Engineering Zhengzhou China

A key problem for an adaptive filter is to establish a suitable adaptive factor for balancing the contributions of the measurements and the predicted state information from some kinematic models. The reasonable adaptive factor needs a reliable learning statistics to judge the state kinematic model errors. After analyzing the existing two kinds of learning statistics based on the state discrepancy and variance component ratio, a new learning statistic based on predicted residuals is set up, which is different from the exiting learning statistics. The new learning statistic does not need to estimate the kinemetic state parameters before the filtering process, Of course, it does not need necessary measurements to estimate state parameters for all observation epochs. The new learning statistic can be applied together with the learning factor constructed by the state discrepancy. The advantages and shortcomings of the new learning factor are analyzed, and an example is given.

关键词： adaptive factor adaptive filter kinematic model predicted residual.

A MATHEMATICAL MODEL FOR UNSTEADY SEDIMENT TRANSPORT IN THE LOWER yellow river

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International Journal of Sediment research 2001年第2期16卷 150-158页

作者： ZHANG Hongwu1, HUANG Yuandong1 and ZHAO Lianjun2 1 Department of hydraulic Engineering, Tsinghua University, Beijing 100084, china 2 yellow river institute of hydraulic research, zhengzhou 4.0003, china Department of hydraulic Engineering Tsinghua University Beijing 100084 China yellow river institute of hydraulic research Zhengzhou 450003 China

A one-dimensional mathematical model for unsteady sediment transport in the Lower yellow river is developed. A coefficient of sediment distribution is defined to represent the ratio of the bottom to the average concentration under the equilibrium conditions. The coefficient is not constant and is evaluated by using an empirical expression obtained by integrating the sediment concentration along water depth. The concentration distributions and the mean diameter distributions of suspended sediment in the transversal direction are also estimated in this model. A four-point (Preismann type) finite difference scheme and TDMA are employed in the numerical method. Three typical floods occurd in 1977,1982 and 1996, respectively, in the Lower yellow river from Tiexie to Shunkou with a length of 393.67km are numerically simulated with the model. The computed results, such as the water stage, discharge, and sediment concentration agree well with the measured data.

关键词： Mathematical model Unsteady sediment transport The Lower yellow river Floods

Back analysis of mechanical parameters of roller compacted concrete dam

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Science china(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1,2,3,LI Bo 1,XU GuangLei 4 &YU Hong 1,2,3 1 State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering,Hohai University,Nanjing 210098,china 2College of Water Conservancy Hydropower,Hohai University,Nanjing 210098,china 3National Engineering research Center of Water Resources Engineering Safety,Efficient Utilization and Nanjing 210098,china 4 Nanjing hydraulic research institute,Nanjing 210029,china 1. State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering Hohai University Nanjing 210098 China2. College of Water Conservancy Hydropower Hohai University Nanjing 210098 China3. National Engineering Research Center of Water Resources Engineering Safety Efficient Utilization and Nanjing Nanjing 210098 China4. Nanjing Hydraulic Research Institute Nanjing 210029 China

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

A DISCUSSION ON CURRENTS AND SUSPENDED LOAD TRANSPORT IN SURF ZONE

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china Ocean Engineering 1989年第2期4卷 195-202页

作者： Zhou Jiabao Senior Engineer, Nanjing hydraulic research institute, Nanjing Nanjing hydraulic research Inst. Nanjing China China

In this paper, the distribution characteristics of the breaking wave current and suspended load transport in the surf zone are discussed in main. Based on the measured data of the waves, the form of breaking wave, the breaking wave current and the sediment concentration of suspended load in the offshore surf zone near Nouakchott, the Islamic Republic of Mauritania, the author has analized the law governing the distribution of longshore current and sediment concentration of suspended load by means of statistical method, and presented a calculation method for the longshore sediment transport in offshore surf zone.

关键词： A DISCUSSION ON CURRENTS AND SUSPENDED LOAD TRANSPORT IN SURF ZONE SURF