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Comparison between gradient based UCODE2005 and the ensemble Kalman Filter for transient groundwater flow inverse modeling

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Science China Earth Sciences 2017年第5期60卷 899-909页

作者： TONG Juxiu bill x hu YANG JinZhong Key Laboratory of Groundwater Cycle and Environment Evolution (China University of Geosciences) Ministry of Education Beijing 100083 China School of Water Resources and Environment China University of Geosciences Beijing 100083 China Department of Earth Ocean and Atmospheric Science/Geological Sciences 108 Carraway Building 909 Antarctic Way Florida State University Tallahassee Florida 32306 USA State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China

Gradient based UCODE_2005 and data assimilation based on the Ensemble Kalman Filter(EnKF) are two different inverse methods. A synthetic two-dimensional flow case with four no-flow boundaries is used to compare the UCODE_2005 with the Ensemble Kalman Filter(EnKF) for their efficiency to inversely calculate and calibrate a hydraulic conductivity field based on hydraulic head data. A zonal, random heterogeneous conductivity field is calibrated by assimilating the time series of heads observed in monitoring wells. The study results indicate that the two inverse methods, UCODE_2005 and EnKF, could be used to calibrate the hydraulic conductivity field to a certain degree. More available observations and information about the conductivity field, more accurate inverse results will be obtained for the UCODE_2005. On the other hand, for a realistic zonal heterogeneous hydraulic conductivity field, EnKF can only efficiently determine the hydraulic conductivity field at the first several assimilated time steps. The results obtained by the UCODE_2005 look better than those by the EnKF. This is possibly due to the fact that the UCODE_2005 uses observed head data at every time step, while EnKF can only use observed heads at first several steps due to the filter divergence problem.

关键词： Inverse methods UCODE2005 Ensemble Kalman Filter Heterogeneous hydraulic conductivity Filter divergence

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Analysis of soluble chemical transfer from soil to surface runoff and incomplete mixing parameter identification

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Water Science and Engineering 2015年第3期8卷 217-225页

作者： Ju-xiu Tong Jin-zhong Yang bill x.hu State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Key Laboratory of Groundwater Cycle and Environment Evolution Ministry of Education China University of Geosciences School of Water Resources and Environment China University of Geosciences

A two-layer mathematical model proposed by Tong et al. （2010） was used to predict soluble chemical transfer from soil into surface runoff with ponded water on the soil surface. Infiltration-related incomplete mixing parameter γ and runoff-related incomplete mixing parameter a in the analytical solution of the Tong et al. （2010） model were assumed to be constant. In this study, different laboratory experimental data of soluble chemical concentration in surface runoff from initially unsaturated and saturated soils were used to identify the variables γ and a based on the analytical solution of the model. The values of γ and a without occurrence of surface runoff were constant and equal to their values at the moment when the surface runoff started. It was determined from the results that γ decreases with the increase of the ponded water depth, and when the initial volumetric water content is closer to the saturated water content, there is less variation of parameter γ after the occurrence of surface runoff. As infiltration increases, the soluble chemical concentration in surface runoff decreases. The values of parameter a range from 0 to 1 for the fine loam and sand under the controlled infiltration conditions, while it can increase to a very large value, greater than 1, for the sand under the restrained infiltration conditions, and the analytical solution of the model is not valid for experimental soil without any infiltration if a is expected to be less than or equal to 1. The soluble chemical concentrations predicted from the model with variable incomplete mixing parameters γ and α are more accurate than those from the model with constant γ and α values.

关键词： Surface runoff Incomplete mixing parameter Analytical solution Soluble chemical

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运用STOMP数值模拟器进行多空介质中尿素水解以及方解石沉淀数值模拟(英文)

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地学前缘 2010年第6期17卷 117-133页

作者：郭娈靖 bill x.hu Idaho National Laboratory Idaho Falls China University of Geosciences(Beijing) Florida State University Tallahassee

遍布于美国能源部所辖野外场地的地下放射性核素和痕量金属污染对美国能源部的长期监管职能提出了最严峻的挑战。目前较有前景的一个原地固化污染物方法是利用尿素酶催化尿素水解,进而推动方解石沉淀及与之共同沉淀。运用STOMP数值模拟... 详细信息

遍布于美国能源部所辖野外场地的地下放射性核素和痕量金属污染对美国能源部的长期监管职能提出了最严峻的挑战。目前较有前景的一个原地固化污染物方法是利用尿素酶催化尿素水解,进而推动方解石沉淀及与之共同沉淀。运用STOMP数值模拟器实施一系列反应性溶质数值模拟来研究系统中水流、运移、反应与反应导致的介质性质变化之间的紧密的非线性耦合,并在研究中系统性增加反应系统的复杂度和物理-化学的非均质性以考察模拟效果。通过调整反应速率表达式中尿素酶浓度和沉淀反应常数,对尿素水解和方解石沉淀速率进行了敏感度分析。结果显示:尿素水解速率是矿物沉淀总量的决定性因素,沉淀物的空间分布既取决于水解速率也取决于沉淀速率;在一维水流柱6个空隙体积的时间段模拟中,观察到了5%的最大空隙度减少;当二维模拟中考虑一个低渗透性包裹体时,被改变的流场重新对生成的沉淀组成物进行了分布,形成了扭曲的反应锋面。模拟结果也显示沉淀在低渗透性区域边界上形成,这说明位于这个区域里面的污染物可能被囊裹而从流线中被隔离起来。

关键词：数值模拟原地污染治理尿素水解方解石沉淀 STOMP

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基于去丛聚效应的裂隙岩体渗透性分析

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工程勘察 2007年第3期35卷 21-26,30页

作者：蒋小伟万力梁四海 bill x.hu 中国地质大学水资源与环境学院北京100083 Department of Geological Sciences Florida State UniversityTallahassee

以表征岩体渗透性的单位吸水量ω为参数,采用基于像元的去丛聚效应方法有效地分析了裂隙岩体的渗透性空间分布规律。将研究区的单位吸水量ω筛选并经权系数校正后,研究发现岩体渗透性参数ω服从对数正态分布规律;各地层的ω均值有较大差... 详细信息

以表征岩体渗透性的单位吸水量ω为参数,采用基于像元的去丛聚效应方法有效地分析了裂隙岩体的渗透性空间分布规律。将研究区的单位吸水量ω筛选并经权系数校正后,研究发现岩体渗透性参数ω服从对数正态分布规律;各地层的ω均值有较大差异,表现出层状渗透结构特征;断层影响带中含泥量最少的T41地层,其渗透性明显大于其它区同地层的渗透性,表现出带状渗透结构特征。在此研究的基础上,再将去丛聚效应方法应用到渗透性垂向变化规律的研究,结果表明全区及各分区ω在一定范围内随埋深表现出负指数分布规律,表现出壳状渗透结构特征。这些规律为裂隙岩体的渗流计算和模拟奠定了基础。

关键词：去丛聚效应裂隙岩体渗透性对数正态分布渗透结构

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砂泥岩裂隙岩体埋深和岩性对渗透性影响分析

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水科学进展 2008年第4期19卷 574-580页

作者：蒋小伟万力胡晓农中国地质大学水资源与环境学院 Department of Geological Sciences Florida State UniversityTallahasseeFlorida USA32306

采用表征岩体渗透性的单位吸水量ω为参数,有效地分析了砂泥岩裂隙岩体中相对埋深和岩性对渗透性空间分布规律的影响。研究区内,在不同深度单位吸水量的最大值和最小值相差3-4个数量级,渗透性表现出显著的随机特征。通过将压水试验数据... 详细信息

采用表征岩体渗透性的单位吸水量ω为参数,有效地分析了砂泥岩裂隙岩体中相对埋深和岩性对渗透性空间分布规律的影响。研究区内,在不同深度单位吸水量的最大值和最小值相差3-4个数量级,渗透性表现出显著的随机特征。通过将压水试验数据离散化并在不同深度上取logω的平均值,凸现了渗透性的结构特征。ω均值在一定范围内随相对深度表现出负指数分布规律;剔除logω的线性趋势项后,logω残差表现出与地层内部岩性相对应的规律。此外,研究还发现,渗透性参数随相对深度呈负指数分布规律是由含裂隙的砂岩介质引起的。这些规律为裂隙岩体的渗流计算和模拟奠定了基础。文章所提出的对压水试验数据离散化并在不同深度取均值以找出渗透性和深度关系,以及去除线性趋势项研究渗透性和岩性之间关系等方法具有广泛的应用价值。

关键词：裂隙岩体渗透性负指数分布软岩分布

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A time-space network-based model for transportation service optimization of China Railway Express

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High-speed Railway 2024年第3期2卷 153-163页

作者： Yin W. hu W. Yan x. Peng B. Yang x. College of Urban Rail Transit and Logistics Beijing Union University Beijing 100101 China School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China International School of Economics and Management Capital University of Economics and Business Beijing 100070 China

This paper describes the development and optimization plans for the China Railway Express (CR Express). As a new type of international land transport organization, CR Express has emerged with the continuous expansion of China toward European investment and trade, and in particular, has expanded with the continuous progress of the One Belt and One Road (OBOR) initiative. In addition to improving the service quality of CR Express, the operating costs must be reduced for developing “smart railways” that serve “smart cities”. We propose a dual-objective-based function mathematical optimization model; the satisfaction of the cargo owner is considered, and the timeliness, transportation capacity, and goods category constraints of CR Express transportation are designed. Moreover, we present the normalized equivalent method of the two-objective function of the model. Finally, a case study is conducted against the background of certain trains in the western corridor of CR Express to validate the effectiveness of the model and research methods proposed in this study. © 2024 Beijing Jiaotong University

关键词： China Railway Express Mathematical optimization One Belt and One Road Time-space network Transportation service

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Effect of CO_(2) Opposing Multiple Jets on Thermoacoustic Instability and NO_(x) Emissions in a Lean-Premixed Model Combustor

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Journal of Thermal Science 2024年第1期33卷 207-221页

作者： ZHOU Hao hu Liubin Institute for Thermal Power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China

This paper experimentally studied the effect of CO_(2) opposing multiple jets on the thermoacoustic instability and NO_(x) emissions in a lean-premixed model *** feasibility was verified from three variables:the CO_(2) jet flow rate,hole numbers,and hole diameters of the *** indicate that the control effect of thermoacoustic instability and NO_x emissions show a reverse trend with the increase of open area ratio on the whole,and the optimal jet flow rate range is 1-4 L/min with CO_(2) opposing multiple *** this flow rate range,the amplitude and frequency of the dynamic pressure and heat release signals CH~* basically decrease as the CO_(2) flow rate increases,which avoids high-frequency and high-amplitude thermoacoustic *** amplitude-damped ratio of dynamic pressure and CH*can reach as high as 98.75% and 93.64% with an optimal open area ratio of 3.72%.NO_(x) emissions also decrease as the jet flow rate increases,and the maximum suppression ratio can reach 68.14%.Besides,the flame shape changes from a steep inverted "V" to a more flat "M",and the flame length will become shorter with CO_(2) opposing multiple *** research achieved the synchronous control of thermoacoustic instability and NO_(x) emissions,which could be a design reference for constructing a safer and cleaner combustor.

关键词： thermoacoustic instability lean-premixed model combustor CO_(2)opposing multiple jets open area ratio NO_(x)emissions

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Near-Field Heat Transfer Enhancement of SiC-hBN-InSb Thermophotovoltaic System by Graphene Strong Coupling Effects

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Journal of Thermal Science 2024年第4期33卷 1409-1420页

作者： xU Zhiguo hu Zhifang School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240China

Near-field thermophotovoltaic(NTPV)devices comprising a SiC-hBN-graphene emitter and a graphene-InSb cell with gratings are designed to enhance the performance of the NTPV *** electrodynamics and rigorous coupled-wave analysis are employed to calculate radiative heat transfer *** is found that the NTPV systems with two graphene ribbons perform better due to the graphene strong coupling *** effects of graphene chemical potential are *** is demonstrated that near-field radiative heat transfer of thermophotovoltaic devices is enhanced by the coupling of surface plasmon polaritons,surface phonon polaritons,hyperbolic phonon polaritons,and magnetic polaritons caused by the graphene strong coupling *** splitting frequency of different polaritons is calculated to quantify the mutual interaction of graphene strong coupling ***,the effects of cell grating filling ratio are *** excitation of magnetic polaritons is affected by the graphene ribbon and the cell filling *** investigation provides a new explanation of the enhancement mechanism of graphene-assisted thermophotovoltaic systems and a novel approach for improving the output power of the near-field thermophotovoltaic system.

关键词： near-field radiative heat transfer thermophotovoltaics strong coupling effect multiple magnetic polaritons graphene-hbn heterostructures

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Fracture mechanism of inclusions in thick plate center under tensile loading

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Journal of Iron and Steel Research International 2024年第5期31卷 1196-1209页

作者： Lei hu Li-qin Zhang Feng hu Guo-hong Zhang Kuan Zheng Collaborative Innovation Center for Advanced Steels Wuhan University of Science and TechnologyWuhan430081HubeiChina Department of Applied Physics Wuhan University of Science and TechnologyWuhan430081HubeiChina Analysis and Testing Center Wuhan University of Science and TechnologyWuhan430081HubeiChina

Segregation of solute atoms in the center of thick plates of the tempered steel can cause an inhomogeneous structural transformation and generate micron-sized inclusions,which leads to lamellar tearing of thick plate and decreases the plasticity and *** formation and fragmentation mechanisms of micron-sized inclusions,like MnS and(Nb,Ti)C,in the center of thick plates were investigated by using thermodynamic calculations,finite element simulations,and electron backscatter diffraction characterization *** results show that micron-sized inclusions nucleate and grow in the liquid phase,and under tensile loading,they exhibit three fragmentation *** local stress during the fragmentation of inclusions is lower than the critical fracture stress of adjacent grains,and phase boundaries can effectively impede crack propagation into the *** existence of a low proportion of high-angle grain boundaries(58.1%)and high Kernel average misorientation value(0.534°)in the segregation band promotes inclusions fragmentation and crack *** difference in crack initiation and propagation direction caused by the morphology of inclusions and physical properties,as well as different matrix arrest abilities,is the main reasons for the diversity of inclusion fragmentation.

关键词： Thick plate Inclusion Finite element simulation Critical fracture stress Fracture mechanism

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泥质潮滩的海水-地下水交换量化研究——以莱州湾南岸为例

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海洋通报 2018年第4期37卷 450-458页

作者：常雅雯胡晓农张汉雄陈麟中国地质大学(北京)水资源与环境学院北京100083

本文目的是利用数值模拟量化研究莱州湾南岸泥质潮滩的海水-地下水交换。选取的典型剖面长约3 800 m,坡度小于1%,沿剖面选取5个监测点,观测地下水的水头和盐度,分析其随时间的变化规律。概化水文地质条件基础上,用SEAWAT-2000建立二维... 详细信息

本文目的是利用数值模拟量化研究莱州湾南岸泥质潮滩的海水-地下水交换。选取的典型剖面长约3 800 m,坡度小于1%,沿剖面选取5个监测点,观测地下水的水头和盐度,分析其随时间的变化规律。概化水文地质条件基础上,用SEAWAT-2000建立二维数值模型,模拟水流的流动并将水头模拟值和观测值进行拟合。基于良好的拟合结果,计算出海底地下水排泄(Submarine Groundwater Discharge,SGD)量为17.46 m3/m/d,海水流入量为2.71 m^3/m/d。文章最后提出了观测和模拟过程中存在的问题,需要今后进一步解决。

关键词：莱州湾南岸数值模拟海底地下水排泄海水流入量

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