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Land use/cover change effects on floods with different return periods: a case study of Beijing, China

Yueling WANG, Xiaoliu YANG

《环境科学与工程前沿（英文）》 2013年第7卷第5期页码 769-776 doi: 10.1007/s11783-013-0542-z

摘要： In this study, an approach integrating digital land use/cover change (LUCC) analysis, hydraulic modeling and statistical methods was applied to quantify the effect of LUCC on floods in terms of inundation extent, flood arrival time and maximum water depth. The study took Beijing as an example and analyzed five specific floods with return periods of 20-year, 50-year, 100-year, 1000-year and 10000-year on the basis of LUCC over a nine-year period from 1996 to 2004. The analysis reveals that 1) during the period of analysis Beijing experienced unprecedented LUCC; 2) LUCC can affect inundation extent and flood arrival time, and floods with longer return periods are more influenced; 3) LUCC can affect maximum water depth and floods with shorter return periods are more influenced; and 4) LUCC is a major flood security stressor for Beijing. It warns that those cities having experienced rapid expansion during recent decades in China are in danger of more serious floods and recommends that their actual land use patterns should be carefully assessed considering flood security. This integrated approach is demonstrated to be a useful tool for joint assessment, planning and management of land and water.

关键词： inundation extent flood arrival time maximum water depth shallow flow model

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Prediction of hydro-suction dredging depth using data-driven methods

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 652-664 doi: 10.1007/s11709-021-0719-7

摘要： In this study, data-driven methods (DDMs) including different kinds of group method of data handling (GMDH) hybrid models with particle swarm optimization (PSO) and Henry gas solubility optimization (HGSO) methods, and simple equations methods were applied to simulate the maximum hydro-suction dredging depth (h_s). Sixty-seven experiments were conducted under different hydraulic conditions to measure the h_s. Also, 33 data samples from three previous studies were used. The model input variables consisted of pipeline diameter (d), the distance between the pipe inlet and sediment level (Z), the velocity of flow passing through the pipeline (u₀), the water head (H), and the medium size of particles (D₅₀). Data-driven simulation results indicated that the HGSO algorithm accurately trains the GMDH methods better than the PSO algorithm, whereas the PSO algorithm trained simple simulation equations more precisely. Among all used DDMs, the integrative GMDH-HGSO algorithm provided the highest accuracy (RMSE = 7.086 mm). The results also showed that the integrative GMDHs enhance the accuracy of polynomial GMDHs by ~14.65% (based on the RMSE).

关键词： sedimentation water resources dam engineering machine learning heuristic

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Investigating the raveling test for full-depth reclamation

Robert HILL, Andrew BRAHAM

《结构与土木工程前沿（英文）》 2018年第12卷第2期页码 222-226 doi: 10.1007/s11709-017-0423-9

摘要： Full-Depth Reclamation (FDR) is a sustainable method of building pavement structure compared to more traditional rehabilitation methods. Traffic is generally returned to an FDR project before a surface course is applied, as water in the FDR needs time to evaporate from the structure. This should not be done too quickly or raveling occurs. Currently, there is no test to quantify the timing of return to traffic. In this study, the “Raveling test of cold mixed bituminous emulsion samples” (ASTM D7196) was used to compare asphalt emulsion and asphalt foam FDR. Asphalt emulsion samples were cured at ambient and 40 °C temperatures, while asphalt foam samples were cured at ambient temperatures. Raveling test data was collected from 0 to 48 hours of curing, however, samples were often not able to withstand fifteen minutes of testing. Therefore, the “time lasted” (the time the raveling head loses contact with the surface of the sample) was recorded. In general, the asphalt emulsion samples that were cured in the oven at 40 °C had a longer time lasted and showed higher potential for determination of return to traffic. In addition, the asphalt emulsion samples had a longer time lasted than the asphalt foam samples at ambient temperatures.

关键词： raveling full depth reclamation

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Multivariable regression model for Fox depth correction factor

Ravi Kant MITTAL, Sanket RAWAT, Piyush BANSAL

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 103-109 doi: 10.1007/s11709-018-0474-6

摘要： This paper presents a simple and efficient equation for calculating the Fox depth correction factor used in computation of settlement reduction due to foundation embedment. Classical solution of Boussinesq theory was used originally to develop the Fox depth correction factor equations which were rather complex in nature. The equations were later simplified in the form of graphs and tables and referred in various international code of practices and standard texts for an unsophisticated and quick analysis. However, these tables and graphs provide the factor only for limited values of the input variables and hence again complicates the process of automation of analysis. Therefore, this paper presents a non-linear regression model for the analysis of effect of embedment developed using “IBM Statistical Package for the Social Sciences” software. Through multiple iterations, the value of coefficient of determination is found to reach 0.987. The equation is straightforward, competent and easy to use for both manual and automated calculation of the Fox depth correction factor for wide range of input values. Using the developed equation, parametric study is also conducted in the later part of the paper to analyse the extent of effect of a particular variable on the Fox depth factor.

关键词： settlement embedment Fox depth correction factor regression multivariable

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水库调度的最优控制模型与最大值原理求解方法

方强,王先甲,方德斌

《中国工程科学》 2007年第9卷第4期页码 55-59

摘要：

试图用最优控制理论来描述水库调度的连续变化特性，建立了水库调度的最优控制模型，用最大值原理给出了水库调度最优控制的必要条件，分析了不同条件和环境下水库调度最优控制策略和具体表示形式。最后对某具体算例进行了分析，结果表明该方法是有效的。

关键词：水利管理最优控制模型最大值原理水库调度

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Implementation of photovoltaic water pumping system with MPPT controls

Najet REBEI,Ali HMIDET,Rabiaa GAMMOUDI,Othman HASNAOUI

《能源前沿（英文）》 2015年第9卷第2期页码 187-198 doi: 10.1007/s11708-015-0359-5

摘要： To increase the output efficiency of a photovoltaic (PV) system, it is important to apply an efficient maximum power point tracking (MPPT) technique. This paper describes the analysis, the design and the experimental implementation of the tracking methods for a stand-alone PV system, using two approaches. The first one is the constant voltage (CV) MPPT method based on the optimum voltage, which was deduced experimentally, and considered as a reference value to extract the optimum power. The second one is the increment conductance (Inc-Cond) MPPT method based on the calculation of the power derivative extracted by the installation. The output controller can adjust the duty ratio to the optimum value. This optimum duty ratio is the input of a DC/DC boost converter which feeds a set of Moto-pump via a DC/AC inverter. This paper presents the details of the two approaches implemented, based on the system performance characteristics. Contributions are made in several aspects of the system, including converter design, system simulation, controller programming, and experimental setup. The MPPT control algorithms implemented extract the maximum power point (MPP), with satisfactory performance and without steady-state oscillation. MATLAB/Simulink and dSpace DS1104 are used to conduct studies and implement algorithms. The two proposed methods have been validated by implementing the performance of the PV pumping systems installed on the roof of the research laboratory in INSAT Tunisia. Experimental results verify the feasibility and the improved functionality of the system.

关键词： photovoltaic generator (PVG) maximum power point tracking (MPPT) boost DC/DC converter DC/AC inverter moto-pump

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Particle swarm optimization model to predict scour depth around a bridge pier

Shahaboddin SHAMSHIRBAND, Amir MOSAVI, Timon RABCZUK

《结构与土木工程前沿（英文）》 2020年第14卷第4期页码 855-866 doi: 10.1007/s11709-020-0619-2

摘要： Scour depth around bridge piers plays a vital role in the safety and stability of the bridges. The former approaches used in the prediction of scour depth are based on regression models or black box models in which the first one lacks enough accuracy while the later one does not provide a clear mathematical expression to easily employ it for other situations or cases. Therefore, this paper aims to develop new equations using particle swarm optimization as a metaheuristic approach to predict scour depth around bridge piers. To improve the efficiency of the proposed model, individual equations are derived for laboratory and field data. Moreover, sensitivity analysis is conducted to achieve the most effective parameters in the estimation of scour depth for both experimental and filed data sets. Comparing the results of the proposed model with those of existing regression-based equations reveal the superiority of the proposed method in terms of accuracy and uncertainty. Moreover, the ratio of pier width to flow depth and ratio of 50 (mean particle diameter) to flow depth for the laboratory and field data were recognized as the most effective parameters, respectively. The derived equations can be used as a suitable proxy to estimate scour depth in both experimental and prototype scales.

关键词： scour depth bridge design and construction particle swarm optimization computational mechanics artificial intelligence bridge pier

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A control scheme with performance prediction for a PV fed water pumping system

Ramesh K GOVINDARAJAN,Pankaj Raghav PARTHASARATHY,Saravana Ilango GANESAN

《能源前沿（英文）》 2014年第8卷第4期页码 480-489 doi: 10.1007/s11708-014-0334-6

摘要： This paper focuses on modeling and performance predetermination of a photovoltaic (PV) system with a boost converter fed permanent magnet direct current (PMDC) motor-centrifugal pump load, taking the converter losses into account. Sizing is done based on the maximum power generated by the PV array at the average irradiation. Hence optimum sizing of the PV array for the given irradiation at the geographical location of interest is obtained using the predetermined values. The analysis presented here involves systems employing maximum power point tracking (MPPT) as they are more efficient than directly coupled systems. However, the voltage and power of the motor might rise above rated values for irradiations greater than the average when employing MPPT, hence a control scheme has been proposed to protect the PMDC motor from being damaged during these conditions. This control scheme appropriately chooses the optimum operating point of the system, ensuring long-term sustained operation. The numerical simulation of the system is performed in Matlab/Simulink and is validated with experimental results obtained from a 180 V, 0.5 hp PMDC motor coupled to a centrifugal pump. The operation of the system with the proposed control scheme is verified by varying the irradiation levels and the relevant results are presented.

关键词： photovoltaic system boost converter maximum power point tracking (MPPT) DC permanent-magnet motor centrifugal pump

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Depth of cut models for multipass abrasive waterjet cutting of alumina ceramics with nozzle oscillation

Jun WANG

《机械工程前沿（英文）》 2010年第5卷第1期页码 19-32 doi: 10.1007/s11465-009-0082-1

摘要： An experimental study of the depth of cut in multipass abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented. It is found that this cutting technique can significantly increase the depth of cut by an average of 50.8% as compared to single pass cutting without nozzle oscillation under the corresponding cutting conditions and within the same cutting time. Predictive models for the depth of cut are then developed. The modelling process starts with single pass cutting using a dimensional analysis technique and the particle erosion theories applied to alumina ceramics, before progressing to the development of the models for multipass cutting. The models are finally assessed both qualitatively and quantitatively with experimental data. It is shown that the model predictions are in good agreement with the experimental data with the average deviations of about 1%.

关键词： abrasive waterjet engineering ceramics depth of cut cutting performance nozzle oscillation machining

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Effect of biological activated carbon filter depth and backwashing process on transformation of biofilm

Wanqi Qi, Weiying Li, Junpeng Zhang, Xuan Wu, Jie Zhang, Wei Zhang

《环境科学与工程前沿（英文）》 2019年第13卷第1期 doi: 10.1007/s11783-019-1100-0

摘要：

We studied BAC biofilm during the process of initial operation and backwash.

Microbial diversity decreased gradually with the increase of BAC filter depth.

Proteobacteria dominated at the phylum level among the BAC biofilm samples.

α-proteobacteria increased about 10% in all carbon filter depth after backwash.

关键词： Biological activated carbon Biofilm Community structure Carbon filter depth High-throughput sequencing

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Principle of maximum entropy for reliability analysis in the design of machine components

Yimin ZHANG

《机械工程前沿（英文）》 2019年第14卷第1期页码 21-32 doi: 10.1007/s11465-018-0512-z

摘要： We studied the reliability of machine components with parameters that follow an arbitrary statistical distribution using the principle of maximum entropy (PME). We used PME to select the statistical distribution that best fits the available information. We also established a probability density function (PDF) and a failure probability model for the parameters of mechanical components using the concept of entropy and the PME. We obtained the first four moments of the state function for reliability analysis and design. Furthermore, we attained an estimate of the PDF with the fewest human bias factors using the PME. This function was used to calculate the reliability of the machine components, including a connecting rod, a vehicle half-shaft, a front axle, a rear axle housing, and a leaf spring, which have parameters that typically follow a non-normal distribution. Simulations were conducted for comparison. This study provides a design methodology for the reliability of mechanical components for practical engineering projects.

关键词： machine components reliability arbitrary distribution parameter principle of maximum entropy

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Capturing the opportunities to initiate an in-depth integration of traditional Chinese medicine and western

null

《医学前沿（英文）》 2014年第8卷第3期页码 268-271 doi: 10.1007/s11684-014-0369-4

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Experimental study on performance of passive and active solar stills in Indian coastal climatic condition

R. LALITHA NARAYANA, V. RAMACHANDRA RAJU

《能源前沿（英文）》 2020年第14卷第1期页码 105-113 doi: 10.1007/s11708-018-0536-4

摘要： This present work is aimed to examine the effect of mass flow rate on distillate output and performance of a solar still in active mode. Outdoor experiments were conducted at the coastal town, Kakinada (16° 93′N/83° 33′E), Andhra Pradesh, India. A solar still with a 30° of fixed cover inclination, 1m of effective basin area, and a flat-plate collector (FPC) with an effective area of 2 m were used. An attempt was also made earlier in passive mode to optimize the water depth for the same solar still for maximum yield and distillation efficiency. For the passive still, it is observed that the capacity of heat storage and heat drop are significant parameters that affect the still performance. For the selected still design, the study reveals that 0.04 m water depth is the optimum value for specific climatic conditions. In the active solar still, with the optimum water depth, different flow rates of 0.5, 1 and 1.5 L/min are considered through FPC. It is observed that both the mass flow rate and the variation of internal heat transfer coefficients with the mass flow rate have a significant effect on the yield and performance of the still. The experimental results show that the combination of 1.5 L/min mass flow rate and an optimum water depth of 0.04m leads to a maximum yield for the active solar still. The enhanced yield of the active solar still is 57.55%, compared with that of the passive solar still, due to increase in area of radiation collection and more heat absorption rate.

关键词： distillation efficiency solar still heat transfer coefficient water depth optimum and mass flow rate

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Fractional order extremum seeking approach for maximum power point tracking of photovoltaic panels

Ammar NEÇAIBIA,Samir LADACI,Abdelfatah CHAREF,Jean Jacques LOISEAU

《能源前沿（英文）》 2015年第9卷第1期页码 43-53 doi: 10.1007/s11708-014-0343-5

摘要： Due to the high interest in renewable energy and diversity of research regarding photovoltaic (PV) array, a great research effort is focusing nowadays on solar power generation and its performance improvement under various weather conditions. In this paper, an integrated framework was proposed, which achieved both maximum power point tracking (MPPT) and minimum ripple signals. The proposed control scheme was based on extremum-seeking (ES) combined with fractional order systems (FOS). This auto-tuning strategy was developed to maximize the PV panel output power through the regulation of the voltage input to the DC/DC converter in order to lead the PV system steady-state to a stable oscillation behavior around the maximum power point (MPP). It is shown that fractional order operators can improve the plant dynamics with respect to time response and disturbance rejection. The effectiveness of the proposed controller scheme is illustrated with simulations using measured solar radiation data.

关键词： extremum seeking (ES) fractional order control (FOC) fractional calculus photovoltaic (PV) panel maximum power point tracking (MPPT)

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Carbonation depth prediction of fly ash concrete subjected to 2- and 3-dimensional CO attack

CHEN Shudong, SUN Wei, ZHANG Yunsheng, GUO Fei

《结构与土木工程前沿（英文）》 2008年第2卷第4期页码 395-400 doi: 10.1007/s11709-008-0046-2

摘要： Based on accelerated carbonation test, 1D, 2D and 3D carbonation of high performance concrete with different fly ash contents (0%, 15%, 20%, 40%, 60%) were studied. The interaction coefficients of 2D and 3D carbonation are defined. The time-dependent coefficient of carbon dioxide diffusion and the interaction coefficients of 2D and 3D carbonation are analyzed. The mathematical model which includes and is deduced. The experiments indicate that 2D and 3D carbonation have obvious interaction. Interaction coefficients obey the attenuation function through time . The mathematical model of 2D and 3D carbonation life prediction based on Fick scattering law can be solved by Fourier expansion. The life prediction of concrete of Sutong Bridge beam shows that the 1D, 2D, 3D carbonation prediction life are 1595 a, 882 a and 758 a, respectively, 2D and 3D carbonation life predicted are reduced clearly.

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标题作者时间类型操作

Land use/cover change effects on floods with different return periods: a case study of Beijing, China

Yueling WANG, Xiaoliu YANG

期刊论文

Prediction of hydro-suction dredging depth using data-driven methods

期刊论文

Investigating the raveling test for full-depth reclamation

Robert HILL, Andrew BRAHAM

期刊论文

Multivariable regression model for Fox depth correction factor

Ravi Kant MITTAL, Sanket RAWAT, Piyush BANSAL