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Engineering properties of the Bukit Timah granitic residual soil in Singapore

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Underground Space 2019年第2期4卷 98-108页

作者： w.g.zhang R.H.zhang L.Han A.T.C.goh Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqingChina National Joint Engineering Research Center of geohazards Prevention in the Reservoir Areas Chongqing UniversityChongqing 400045China Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of EducationWuhan 430072China School of Civil Engineering Chongqing UniversityChongqingChina School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore

Extensive site investigations were conducted prior to the construction of a Mass Rapid Transit project in Singapore that was predominantly in the Bukit Timah granite(BTg)formation residual *** paper evaluates the engineering properties of the BTg formation residual soil based on data from 208 site investigation boreholes from four different *** on the results from 2481 conventional laboratory tests and 1192 in-situ tests,this paper summarizes the engineering properties of the highly variable BTg residual soil,including conventional composition analysis,index and hydraulic properties,and strength and deformation parameters required for geotechnical analysis and *** on these results,the BTg formation is found to be quite *** the degree of weathering decreases with depth from the top of the formation,the BTg residual soil becomes sandier,with reduced silt and clay *** coefficient of permeability and the compression index of the BTg residual soil vary *** addition,the empirical equations relating the shear strength(index)to the standard penetration test(SPT)-N,as well as the equations and charts for determining stiffness,are *** findings,together with the proposed equations or charts,can be used for design guidance of similar projects related to granitic residual soils in Singapore.

关键词： Bukit Timah granite Residual soil Shear strength Stiffness Laboratory testing In-situ testing

Evolution of deformation twins with strain rate in a mediummanganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V

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Journal of Iron and Steel Research International 2019年第9期26卷 983-990页

作者： J. Chen J.J.wang H.zhang w.g.zhang C.M.Liu Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Baosteel Special Steel Co. Ltd.Shanghai 200940China Northeastern Institute of Metal Materials Co. Ltd.Shenyang 110108LiaoningChina

Microstructure evolutions of the medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V (in wt.%) with stacking-fault energy of 22 mJ m-2 during deformation at strain rate ranging of 10^-2-1 s^-1 were analyzed by means of X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the twinning-induced plasticity effect is the main strengthening mechanism of the studied steel, whilst the transformation-induced plasticity effect only occurs at high strain rate. with an increase in strain rate, volume fraction of the deformation twins, in particular that of the secondary twins, increases significantly along with decreasing average size. when applied strain rate is higher than 10^-1 s^-1, the parallel deformation twins are turned into a crossing morphology, and the original straight twin boundaries exhibit a ladder feature, which is attributed to the interactions between regular dislocations and twin dislocations at the twin boundary. The critical strain, a key indicator of the initiation of deformation twin, decreases with increasing strain rate. In addition, the ductility and strength of medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V are mainly determined by the shape and volume fraction of deformation twins.

关键词： Medium-manganese wear-resistant steel Stacking fault Twinning-induced plasticity effect Secondary twin Strain hardening rate

Performance of braced excavation in residual soil with groundwater drawdown

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Underground Space 2018年第2期3卷 150-165页

作者： w.g.zhang A.T.C.goh K.H.goh O.Y.S.Chew D.Zhou Runhong zhang Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqingChina School of Civil Engineering Chongqing UniversityChongqingChina School of Civil and Envirormental Engineering Nanyang Technological UniversitySingapore Civil Design Division Land Transport AuthoritySingapore geotechmical cand Tunnels Division Land Transport AuthoritySingapore

In densely built-up Singapore,relatively stiffsecant-bored piles and diaphragm walls are commonly used in cut-and-cover works to minimize the impact of ground movement on the adjacent structures and *** excavations in stiffresidual soil deposits,the asso-ciated wall deﬂections and ground settlements are generally smaller than for excavations in soft soil ***,if the residual soil permeability is high and the underlying rock is highlyﬁssured or fractured,substantial groundwater drawdown and associated seepage-induced settlement may *** this study,the excavation performance of four sites in residual soil deposits with maximum excavation depths between 20 and 24 m is *** maximum wall deﬂections were found to be relatively small compared to the signiﬁcantly larger maximum ground settlements,owing to the extensive lowering of the groundwater *** this paper,details of the subsurface conditions,excavation support system,ﬁeld instrumentation,and observed excavation responses are presented,with particular focus on the large groundwater drawdown and associated ground ***ﬁc issues encountered during the excavation,as well as the effectiveness of various groundwater control measures,are *** case studies will provide useful references and insights for future projects involving braced excavations in residual soil.

关键词： Residual soil Braced excavation wall deﬂection ground settlements groundwater drawdown Strut force

Soft computing approach for prediction of surface settlement induced by earth pressure balance shield tunneling

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Underground Space 2021年第4期6卷 353-363页

作者： w.g.zhang H.R.Li C.Z.wu Y.Q.Li Z.Q.Liu H.L.Liu Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China National Joint Engineering Research Center of geohazards Prevention in the Reservoir Areas Chongqing UniversityChongqing 400045China School of Civil Engineering Chongqing UniversityChongqing 400045China Norwegian geotechnical Institute(NgI) Sognsveien 720855 OsloNorway

Estimating surface settlement induced by excavation construction is an indispensable task in tunneling,particularly for earth pressure balance(EPB)shield *** this study,predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting(XgBoost),artificial neural network,support vector machine,and multivariate adaptive regression *** from three tunnel construction projects in Singapore were used,with main input parameters of cover depth,advance rate,earth pressure,mean standard penetration test(SPT)value above crown level,mean tunnel SPT value,mean moisture content,mean soil elastic modulus,and grout *** performances of these soft computing models were evaluated by comparing predicted deformation with measured *** demonstrate the acceptable accuracy of the model in predicting ground settlement,while XgBoost demonstrates a slightly higher *** addition,the ensemble method of XgBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.

关键词： EPB Surface settlement Soft computing XgBoost Multivariate adaptive regression spline

Numerical Simulation of Radiation Transport to Improve Microalgae Cultivation in an Air-Lift Photobioreactor

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Journal of Thermal Science 2025年第1期34卷 62-76页

作者： zhang Xianbin LI Mingjia HUNg Tzuchen zhang Zixun Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi'an Jiaotong University School of Mechanical Engineering Beijing Institute of Technology Department of Mechanical Engineering Taipei University of Technology

A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling *** purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs) in order to improve the light conditions for microalgae and enhance the photosynthetic *** fluid dynamics(CFD) is used to simulate its internal hydrodynamic *** Lagrangian method is employed to track the movement of microalgae *** radiative transfer equation(RTE)is used to obtain light intensity *** combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU) to calculate the microalgae growth *** numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae *** effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth *** using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.

关键词： light distribution particle tracking photobioreactor structure optimization

Melting Evaluation of Phase Change Materials Impregnated into Cascaded Metal Foams with Regionalized Enhancement

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Journal of Thermal Science 2025年第1期34卷 223-241页

作者： wEI Xinyi zhang Nan zhang Zhaoli CAO Xiaoling YUAN Yanping School of Mechanical Engineering Southwest Jiaotong University

Metal foam promotes the heat transfer of phase change materials(PCMs) in the penalty of reducing the energy storage density of the composite *** this work,the effects of constant porosity(0.96,0.94,0.92,or 0.90) and pore density(PPI) of metal foam on heat transfer of composite PCMs are *** rate could be enhanced by employing with low porosity copper ***,aiming to the right bottom phase changing "dead region",a regionalized enhancement strategy of cascaded metal foams is *** dynamic melting performances of all the composite PCMs are comprehensively *** results reveal that the cascaded configuration is beneficial for *** show that the horizontal strategy enhances melting performance:a maximum of 17.98% reduction in total melting time could be reached when the rear part porosity is 90%.The energy storage density rate could be raised by 5.48%.Besides,the vertical strategy performs with a better average temperature uniformity of 0.441 and brings a lower temperature in the heated *** sum up,the regionalized enhancement of copper foam provides better performance in the phase change *** shows significant potential for solar heat storage and thermal protection.

关键词： copper metal foam heat transfer enhancement phase change materials regionalized enhancement

The optimal control theory——a scientific approach to fundamentally solving control problems

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Science China(Information Sciences) 2025年第1期68卷 389-391页

作者： Huanshui zhang School of Electrical and Automation Engineering Shandong University of Science and Technology School of Control Science and Engineering Shandong University

The maximum principle has bridged mathematical optimization to optimal control,ushering in significant developments and refinements in optimal control theory,notably during the 1960s with the advent of linear quadratic (LQ)control and linear quadratic estimation (LQE).This progression propelled optimal control theory into further advancements,encompassing stochastic control,robust/H-infinity control,model predictive control (MPC),networked control,and reinforcement learning *** control,established upon a rigorous mathematical foundation,extends static optimization theory to dynamic systems,exhibiting scientific essence,unity,and ***,since its inception,optimal control theory has served as an indispensable core role across all control-related domains,including communication-constrained control in networked systems,consensus control,cooperative control,and reinforcement learning control.

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Method for Estimating the State of Health of Lithium-ion Batteries Based on Differential Thermal Voltammetry and Sparrow Search Algorithm-Elman Neural Network

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Energy Engineering 2025年第1期122卷 203-220页

作者： Yu zhang Daoyu zhang Tiezhouwu School of Electrical and Electronic Engineering Hubei University of TechnologyWuhan430068China

Precisely estimating the state of health(SOH)of lithium-ion batteries is essential for battery management systems(BMS),as it plays a key role in ensuring the safe and reliable operation of battery ***,current SOH estimation methods often overlook the valuable temperature information that can effectively characterize battery aging during capacity ***,the Elman neural network,which is commonly employed for SOH estimation,exhibits several drawbacks,including slow training speed,a tendency to become trapped in local minima,and the initialization of weights and thresholds using pseudo-random numbers,leading to unstable model *** address these issues,this study addresses the challenge of precise and effective SOH detection by proposing a method for estimating the SOH of lithium-ion batteries based on differential thermal voltammetry(DTV)and an SSA-Elman neural ***,two health features(HFs)considering temperature factors and battery voltage are extracted fromthe differential thermal voltammetry curves and incremental capacity ***,the Sparrow Search Algorithm(SSA)is employed to optimize the initial weights and thresholds of the Elman neural network,forming the SSA-Elman neural network *** validate the performance,various neural networks,including the proposed SSA-Elman network,are tested using the Oxford battery aging *** experimental results demonstrate that the method developed in this study achieves superior accuracy and robustness,with a mean absolute error(MAE)of less than 0.9%and a rootmean square error(RMSE)below 1.4%.

关键词： Lithium-ion battery state of health differential thermal voltammetry Sparrow Search Algorithm

Automatic and Rapid Throughflow-Based Optimal Design Method for Multi-Stage Axial-Flow Compressors

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Journal of Thermal Science 2025年第1期34卷 77-91页

作者： LEI Fan zhang Xiawen JU Yaping zhang Chuhua Department of Fluid Machinery and Engineering School of Energy and Power EngineeringXi'an Jiaotong University Production and Environmental Department China Huaneng Group.Co.Ltd. State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University

Throughflow design has the advantages of less time consumption and large optimization space,and thus is the corner stone of advanced design system of multi-stage axial-flow *** majority of relevant studies were limited to the throughflow inverse designs,and quite few works have been till now devoted to the throughflow optimal *** this work,an automatic and rapid throughflow-based optimal design method is proposed for axial-flow compressors in which a throughflow inverse design solver is embedded in optimal genetic algorithm to improve the design efficiency of axial-flow *** types of design parameters in the throughflow inverse design of axial-flow compressors,i.e.,swirl and shroud curve,are simultaneously used to optimize both the blade shape and flow *** proposed method is validated by the redesign optimization of the benchmark axial-flow compressor NASA Stage 35,and the CFD predictions show that the throughflow-based optimization leads to 1.18% efficiency benefit at design *** proposed method is then utilized to the two-dimensional throughflow optimal design of a large-scale 6.5-stage axial-flow industrial *** optimal design results are confirmed by CFD predictions,indicating that the proposed method can effectively improve the design adiabatic efficiency of the compressors by 1.09% within a few minutes on desk-top *** throughflow design implications are also obtained for advanced axial-flow industrial *** work could enhance the capability of throughflow design method and has engineering application value to explore the throughflow optimization space of multi-stage axial-flow compressors.

关键词： NASA