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Concrete corrosion in wastewater systems:Prediction and sensitivity analysis using advanced extreme learning machine

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Frontiers of Structural and Civil Engineering 2021年第2期15卷 444-460页

作者： Mohammad ZOUNEMAT-KERMANI Meysam ALIZAMIR Zaher Mundher YASEEN Reinhard Hinkelmann Department of Water Engineering Shahid Bahonar University of KermanKerman 76169-13439Iran Department of Civil Engineering Hamedan BranchIslamic Azad UniversityHamedan 65181-15743Iran Institute of Research and Development Duy Tan UniversityDa Nang 550000Vietnam Department of Civil Engineering Technische Universitat BerlinBerlin 13355Germany

The implementation of novel machine learning models can contribute remarkably to simulating the degradation of concrete due to environmental factors.This study considers the sulfuric acid corrosive factor in wastewater systems to simulate concrete mass loss using five machine learning models.The models include three different types of extreme learning machines,including the standard,online sequential,and kernel extreme learning machines,in addition to the artificial neural network,classification and regression tree model,and statistical multiple linear regression model.The reported values of concrete mass loss for six different types of concrete are the target values of the machine learning models.The input variability was assessed based on two scenarios prior to the application of the predictive models.For the first assessment,the machine learning models were developed using all the available cement and concrete mixture input variables;the second assessment was conducted based on the gamma test approach,which is a sensitivity analysis technique.Subsequently,the sensitivity analysis of the most effective parameters for concrete corrosion was tested using three different approaches.The adopted methodology attained optimistic and reliable modeling results.The online sequential extreme learning machine model demonstrated superior performance over the other investigated models in predicting the concrete mass loss of different types of concrete.

关键词： sewer systems environmental engineering data-driven methods sensitivity analysis

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Impacts of climate change on water quantity, water salinity, food security, and socioeconomy in Egypt

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Water Science and Engineering 2021年第1期14卷 17-27页

作者： Mohie El Din Mohamed Omar Ahmed Moustafa Ahmed Moussa Reinhard Hinkelmann National Water Research Center Fum Ismailiya CanalShoubra El-Kheima 13411Egypt International Center for Agricultural Research in the Dry Areas Cairo 2416Egypt Nile Research Institute(NRI) National Water Research CenterEl-Qanater 13621Egypt Department of Water Engineering Technische Universit€at Berlin(TU Berlin)Campus El GounaEl Gouna 84513Egypt

Climate change might have direct impacts on water quantity in Egypt and lead to indirect effects on Mediterranean saltwater intrusion to groundwater,which exposes agriculture to vulnerability.This study investigated impacts of climate change on agriculture,with particular regard to food security and socioeconomy,and quantified the effectiveness of cropping pattern adaptation measures by integrating three mathematical models.The BlueM model was used for hydrological simulations of Nasser Lake under flooding scenarios to predict the water supply from the High Aswan Dam.The water and salinity balance(WB-SAL)model was adopted to estimate the water salinity in the Nile Delta.The simulated results from the BlueM and WB-SAL models were integrated with the agricultural simulation model for Egypt(ASME)to project cropping patterns,food security,and socioeconomy throughout the country.The results showed that future climate change will directly affect the total crop area;crop areas for 13 crop types;the self-sufficiency of wheat,rice,cereal,and maize supplies;and socioeconomic indicators.The proposed cropping pattern adaptation measures focus on fixing the crop areas of rice and orchards and providing half of the population with lentils,maize,onion,vegetables,milk,and meat.The adaptation measures have the potential to promote food security without causing deterioration of the socioeconomic situation.However,water availability has much more significant effects on food security and socioeconomy than cropping pattern adaptation measures do.Accordingly,the country should rationalize water use efficiency and increase water supply.©2021 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Climate change Water quantity Salinity Cropping pattern adaptation measures Food security Socioeconomy

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Wave propagation speeds and source term influences in single and integral porosity shallow water equations

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Water Science and Engineering 2017年第4期10卷 275-286页

作者： Ilhan Ozgen Jia-heng Zhao Dong-fang Liang Reinhard Hinkelmann Department of Civil Engineering Technische Universitat BerlinBerlin 13355Germany Department of Engineering University of CambridgeCambridge CB2 1PZUK

In urban flood modeling,so-called porosity shallow water equations(PSWEs),which conceptually account for unresolved structures, e.g.,buildings, are a promising approach to addressing high CPU times associated with state-of-the-art explicit numerical methods. The PSWE can be formulated with a single porosity term, referred to as the single porosity shallow water model(SP model), which accounts for both the reduced storage in the cell and the reduced conveyance, or with two porosity terms: one accounting for the reduced storage in the cell and another accounting for the reduced conveyance. The latter form is referred to as an integral or anisotropic porosity shallow water model(AP model). The aim of this study was to analyze the differences in wave propagation speeds of the SP model and the AP model and the implications of numerical model results. First, augmented Roe-type solutions were used to assess the influence of the source terms appearing in both models. It is shown that different source terms have different influences on the stability of the models. Second, four computational test cases were presented and the numerical models were compared. It is observed in the eigenvalue-based analysis as well as in the computational test cases that the models converge if the conveyance porosity in the AP model is close to the storage porosity. If the porosity values differ significantly, the AP model yields different wave propagation speeds and numerical fluxes from those of the BP model. In this study, the ratio between the conveyance and storage porosities was determined to be the most significant parameter.

关键词： Porosity Macroscopic modeling of urban flooding Wave propagation speed Godunov flux Single porosity shallow water model Anisotropic porosity

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Comparison of depth-averaged concentration and bed load flux sediment transport models of dam-break flow

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Water Science and Engineering 2017年第4期10卷 287-294页

作者： Jia-heng Zhao Ilhan Ozgen Dong-fang Liang Reinhard Hinkelmann Department of Civil Engineering Technische Universitat BerlinBerlin 13355Germany Department of Engineering University of CambridgeCambridge CB2 1PZUK

This paper presents numerical simulations of dam-break flow over a movable bed. Two different mathematical models were compared: a fully coupled formulation of shallow water equations with erosion and deposition terms(a depth-averaged concentration flux model), and shallow water equations with a fully coupled Exner equation(a bed load flux model). Both models were discretized using the cell-centered finite volume method, and a second-order Godunov-type scheme was used to solve the equations. The numerical flux was calculated using a Harten, Lax, and van Leer approximate Riemann solver with the contact wave restored(HLLC). A novel slope source term treatment that considers the density change was introduced to the depth-averaged concentration flux model to obtain higher-order accuracy. A source term that accounts for the sediment flux was added to the bed load flux model to reflect the influence of sediment movement on the momentum of the water. In a onedimensional test case, a sensitivity study on different model parameters was carried out. For the depth-averaged concentration flux model,Manning's coefficient and sediment porosity values showed an almost linear relationship with the bottom change, and for the bed load flux model, the sediment porosity was identified as the most sensitive parameter. The capabilities and limitations of both model concepts are demonstrated in a benchmark experimental test case dealing with dam-break flow over variable bed topography.

关键词： Shallow water Sediment transport Bed load flux model Depth-averaged concentration flux model Dam break

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Establishment of a sediment transport capacity equation on loessal slope via experimental investigation

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International Journal of Sediment Research 2023年第2期38卷 166-174页

作者： Tian Wang Jingsi Li Jingming Hou Peng Li Shengdong Cheng Feng Wang Wen Wang Zhanbin Li Reinhard Hinkelmann State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of Technology Chair of Water Resources Management and Modeling of Hydrosystems Department of Civil Engineering Technische Universit at Berlin Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xi'an University of Technology

Areliable sediment transport capacity function provides response against challenges of soil erosion prediction on the Loess Plateau of China. The popular sediment transport capacity functions are questionable on loess slopes because the experimental conditions from which they were derived, like bed materials, gentle slopes,and surface roughness, are different from soil erosion processes on the loess slopes. Due to the foregoing uncertainty, a suitable sediment transport capacity function was developed based on a flume experiment investigation. The erodible bed experiment was implemented for five unit width discharges(1.3 × 10-4-3.3 × 10-4m2/s) and ten slopes(5.2%-57.7%). The selected sediment transport capacity equations were tested in an applicability evaluation. The results of this evaluation found that the Govers(1990) function had the best performance(P.O.0.5-2.0= 76%, R2= 0.93, RMSE = 0.03 kg/(m·s)), followed by the Yalin(1963) function(P.O.0.5-2.0= 80%, R2= 0.81, RMSE = 0.05 kg/(m·s)), and finally by the Low(1989) function(P.O.0.5-2.0= 72%,R2= 0.79, RMSE = 0.04 kg/(m·s)), where P.O.0.5-2.0is the percentage of estimated values with logarithmic discrepancies with the measured value between 0.5 and 2.0; R2is the coefficient of determination and RMSE is the roof mean squares error. The cohesive sediment incipient motion velocity is introduced into the Govers(1990) function, and the sediment particle parameter is determined from measured experimental data. The developed sediment transport capacity equation has good performance with predicted values corresponding to measured values(P.O.0.5-2.0= 98%, R2= 0.98, RMSE = 0.006 kg/(m·s)). The research results provide an improved sediment transport capacity function on the basis of experiments for steep loessal slopes.

关键词： Experimental investigation Hydraulic conditions Loessal slope Sediment transport capacity

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Preface for special section on flood modeling and resilience

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Water Science and Engineering 2017年第4期10卷 265-266页

作者： Jing-ming Hou Qiu-hua Liang Gang Wang Reinhard Hinkelmann Institute of Water Resources and Hydro-Electric Engineering Xi'an University of Technology State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University School of Engineering Newcastle UniversityNewcastle upon TyneNEI 7RUUK Chair of Water Resources Management and Modeling of Hydrosystems Technische Universitt Berlin

Climate change has led to increased frequency, intensity,and duration of extreme weather events, e.g., intense rainfall,heat waves, droughts, and storm surges, worsened byrapid population growth and urbanization at the global scale.Evidence can be found in the exceptional number of unprecedentedweather extremes and the resulting naturalhazards, especially flooding, as seen in the last few decades.For example, the UK has experienced numerous storms andsevere floods in the last decade, particularly in 2007, 2012,and 2015, with 2012 being recorded as the second wettest year in the UK and the wettest ever in England. These events have resulted in lives lost and tremendous economic damage. The UK is not alone. Similarly unusual weather events have been reported across the globe. In China,different types of flooding threaten 1/10 of the country's total area, millions of hectares of farmland, and over 100 large cities, making it one of the most vulnerable countries to flooding.

关键词： Climate change has led to increased frequency

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