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Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1480-1493 doi: 10.1007/s11709-021-0776-y

摘要： In waterfront geotechnical engineering, seismic and drainage conditions must be considered in the design of retaining structures. This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions. The method comprises the following steps: i) determination of the total head, ii) upper bound solution of seismic active earth thrust, and iii) deduction for the earth pressure distribution. The determination of total head h(x,z) relies on the Fourier series expansions, and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem. Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure. The numerical results confirm the validity of the total head distribution. Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure. The method can be applied to the seismic design of waterfront retaining walls.

关键词： seismic active earth pressure     partial seepage flow     pore pressure     anisotropy     upper bound theorem    

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Analyzing the characterization of pore structures and permeability of diesel contaminated clays under

《结构与土木工程前沿（英文）》   页码 1264-1280 doi: 10.1007/s11709-023-0921-x

摘要： In this study, mercury intrusion porosimetry (MIP) and X-ray micro-computed tomography (XRμCT) were used to characterize the pore structures and investigate the permeability characteristics of clay after aging and contamination with diesel. The results of the MIP tests showed that aging leads to reductions in porosity and average diameter, as well as an increase in tortuosity. The XRμCT analysis yielded consistent results; it showed that aging renders pores more spherical and isotropic and pore surfaces smoother. This weakens the pore connectivity. Micromorphological analysis revealed that aging led to the rearrangement of soil particles, tighter interparticle overlapping, and a reduction in pore space. The combination of MIP and XRμCT provided a comprehensive and reliable characterization of the soil pore structure. An increased diesel content increased the porosity and average diameter and reduced the tortuosity of the pores. Mechanistic analysis showed that aging weakens interparticle cohesion; this causes large agglomerates to break down into smaller agglomerates, resulting in a tighter arrangement and a subsequent reduction in porosity. An increase in diesel content increases the number of large agglomerates and pore spaces between agglomerates, resulting in increased porosity. Both aging and diesel content can weaken the permeation characteristics of soil.

关键词： MIP     XRμCT     aging     diesel content     pore structure     permeability characteristics    

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Catalyst particle shapes and pore structure engineering for hydrodesulfurization and hydrodenitrogenation

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 897-908 doi: 10.1007/s11705-021-2127-x

摘要： Catalyst particle shapes and pore structure engineering are crucial for alleviating internal diffusion limitations in the hydrodesulfurization (HDS)/hydrodenitrogenation (HDN) of gas oil. The effects of catalyst particle shapes (sphere, cylinder, trilobe, and tetralobe) and pore structures (pore diameter and porosity) on HDS/HDN performance at the particle scale are investigated via mathematical modeling. The relationship between particle shape and effectiveness factor is first established, and the specific surface areas of different catalyst particles show a positive correlation with the average HDS/HDN reaction rates. The catalyst particle shapes primarily alter the average HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. An optimal average HDS/HDN reaction rate exists as the catalyst pore diameter and porosity increase, and this optimum value indicates a tradeoff between diffusion and reaction. In contrast to catalyst particle shapes, the catalyst pore diameter and the porosity of catalyst particles primarily alter the surface HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. This study provides insights into the engineering of catalyst particle shapes and pore structures for improving HDS/HDN catalyst particle efficiency.

关键词： hydrodesulfurization     hydrodenitrogenation     particle shape     pore structure    

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Uncoupled state space solution to layered poroelastic medium with anisotropic permeability and compressible pore

Zhiyong AI, Wenze ZENG, Yichong CHENG, Chao WU

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 171-179 doi: 10.1007/s11709-011-0103-0

摘要： This paper presents an uncoupled state space solution to three-dimensional consolidation of layered poroelastic medium with anisotropic permeability and compressible pore fluid. Starting from the basic equations of poroelastic medium, and introducing intermediate variables, the state space equation usually comprising eight coupled state vectors is uncoupled into two sets of equations of six and two state vectors in the Laplace-Fourier transform domain. Combined with the continuity conditions between adjacent layers and boundary conditions, the uncoupled state space solution of a layered poroelastic medium is obtained by using the transfer matrix method. Numerical results show that the anisotropy of permeability and the compressibility of pore fluid have remarkable influence on the consolidation behavior of poroelastic medium.

关键词： uncoupled state space solution     layered poroelastic medium     three-dimensional consolidation     anisotropic permeability     compressible pore fluid    

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Influence of pore structure on biologically activated carbon performance and biofilm microbial characteristics

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1419-1

摘要：

• Pore structure affects biologically activated carbon performance.

关键词： Granular activated carbon     Biologically activated carbon filter     Bacterial community structure     Pore structure    

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Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

《能源前沿（英文）》 2021年 第15卷 第2期   页码 460-472 doi: 10.1007/s11708-021-0733-4

摘要： Water transport is of paramount importance to the cold start of proton exchange membrane fuel cells (PEMFCs). Analysis of water transport in cathode catalyst layer (CCL) during cold start reveals the distinct characteristics from the normal temperature operation. This work studies the effect of CCL mesoscopic pore-morphology on PEMFC cold start. The CCL mesoscale morphology is characterized by two tortuosity factors of the ionomer network and pore structure, respectively. The simulation results demonstrate that the mesoscale morphology of CCL has a significant influence on the performance of PEMFC cold start. It was found that cold-starting of a cell with a CCL of less tortuous mesoscale morphology can succeed, whereas starting up a cell with a CCL of more tortuous mesoscale morphology may fail. The CCL of less tortuous pore structure reduces the water back diffusion resistance from the CCL to proton exchange membrane (PEM), thus enhancing the water storage in PEM, while reducing the tortuosity in ionomer network of CCL is found to enhance the water transport in and the water removal from CCL. For the sake of better cold start performance, novel preparation methods, which can create catalyst layers of larger size primary pores and less tortuous pore structure and ionomer network, are desirable.

关键词： cold start     energy conversion     fuel cells     mesoscale morphology     tortuosity     water management    

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Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated undrained stress paths

Mingjing JIANG, Haijun HU, Jianbing PENG, Serge LEROUEIL

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 225-238 doi: 10.1007/s11709-011-0108-8

摘要： In this paper, an experimental investigation is conducted to study the mechanical behavior of saturated natural loess, saturated natural filling in ground fissure and their corresponding saturated remoulded soils under three consolidated undrained triaxial stress tests, namely, conventional triaxial compression test (CTC), triaxial compression test (TC) and reduced triaxial compression test (RTC). The test results show that stress-strain relation, i.e. strain-softening or strain-hardening, is remarkably influenced by the structure, void ratio, stress path and confining pressure. Natural structure, high void ratio, TC stress path, RTC stress path and low confining pressures are favorable factors leading to strain-softening. Excess pore pressure during shearing is significantly affected by stress path. The tested soils are different from loose sand on character of strain-softening and are different from common clay on excess pore water pressure behavior. The critical states in ′– space in CTC, TC and RTC tests almost lie on one line, which indicates that the critical state is independent of the above stress paths. As for remoulded loess or remoulded filling, the critical state line (CSL) and isotropic consolidation line (ICL) in -log ′ space are almost straight, while for natural loess or natural filling, in -log ′ space there is a turning point on the CSL, which is similar to the ICL.

关键词： stress paths     static liquefaction     natural soil     remoulded soil     loess     structure     total strength indices     excess pore pressure    

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polybenzoxazine-based carbon microspheres with nitrogen functionalities: Effects of mixed solvents on pore

Uthen Thubsuang, Suphawadee Chotirut, Apisit Thongnok, Archw Promraksa, Mudtorlep Nisoa, Nicharat Manmuanpom, Sujitra Wongkasemjit, Thanyalak Chaisuwan

《化学科学与工程前沿（英文）》 2020年 第14卷 第6期   页码 1072-1086 doi: 10.1007/s11705-019-1899-8

摘要： In this study, polybenzoxazine (PBZ)-based carbon microspheres were prepared via a facile method using a mixture of formaldehyde (F) and dimethylformamide (DMF) as the solvent. The PBZ microspheres were successfully obtained at the F/DMF weight ratios of 0.4 and 0.6. These microspheres exhibited high nitrogen contents after carbonization. The microstructures of all the samples showed an amorphous phase and a partial graphitic phase. The porous carbon with the F/DMF ratio of 0.4 showed significantly higher specific capacitance (275.1 F g ) than the reference carbon (198.9 F g ) at 0.05 A g . This can be attributed to the synergistic electrical double-layer capacitor and pseudo-capacitor behaviors of the porous carbon with the F/DMF ratio of 0.4. The presence of nitrogen/oxygen functionalities induced pseudo-capacitance in the microspheres, and hence increased their total specific capacitance. After activation with CO , the specific surface area of the carbon microspheres with the F/DMF ratio of 0.4 increased from 349 to 859 m g and the specific capacitance increased to 424.7 F g . This value is approximately two times higher than that of the reference carbon. The results indicated that the F/DMF ratio of 0.4 was suitable for preparing carbon microspheres with good supercapacitive performance. The nitrogen/oxygen functionalities and high specific surface area of the microspheres were responsible for their high capacitance.

关键词： PBZ     carbon     porous materials     microsphere     supercapacitor    

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Applications of atomic force microscopy in immunology

Jiping Li, Yuying Liu, Yidong Yuan, Bo Huang

《医学前沿（英文）》 2021年 第15卷 第1期   页码 43-52 doi: 10.1007/s11684-020-0769-6

摘要： Cellular mechanics, a major regulating factor of cellular architecture and biological functions, responds to intrinsic stresses and extrinsic forces exerted by other cells and the extracellular matrix in the microenvironment. Cellular mechanics also acts as a fundamental mediator in complicated immune responses, such as cell migration, immune cell activation, and pathogen clearance. The principle of atomic force microscopy (AFM) and its three running modes are introduced for the mechanical characterization of living cells. The peak force tapping mode provides the most delicate and desirable virtues to collect high-resolution images of morphology and force curves. For a concrete description of AFM capabilities, three AFM applications are discussed. These applications include the dynamic progress of a neutrophil-extracellular-trap release by neutrophils, the immunological functions of macrophages, and the membrane pore formation mediated by perforin, streptolysin O, gasdermin D, or membrane attack complex.

关键词： cellular mechanics     atomic force microscopy     neutrophil extracellular trap     macrophage phagocytosis     pore formation    

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Pore-scale simulation of water/oil displacement in a water-wet channel

Jin Zhao, Guice Yao, Dongsheng Wen

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 803-814 doi: 10.1007/s11705-019-1835-y

摘要： Water/oil flow characteristics in a water-wet capillary were simulated at the pore scale to increase our understanding on immiscible flow and enhanced oil recovery. Volume of fluid method was used to capture the interface between oil and water and a pore-throat connecting structure was established to investigate the effects of viscosity, interfacial tension (IFT) and capillary number ( ). The results show that during a water displacement process, an initial continuous oil phase can be snapped off in the water-wet pore due to the capillary effect. By altering the viscosity of the displacing fluid and the IFT between the wetting and non-wetting phases, the snapped-off phenomenon can be eliminated or reduced during the displacement. A stable displacement can be obtained under high number conditions. Different displacement effects can be obtained at the same number due to its significant influence on the flow state, i.e., snapped-off flow, transient flow and stable flow, and ultralow IFT alone would not ensure a very high recovery rate due to the fingering flow occurrence. A flow chart relating flow states and the corresponding oil recovery factor is established.

关键词： VOF     pore scale     immiscible displacement     EOR     snap-off     Ca    

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Influence of pore size and membrane surface properties on arsenic removal by nanofiltration membranes

Nathalie Tanne, Rui Xu, Mingyue Zhou, Pan Zhang, Xiaomao Wang, Xianghua Wen

《环境科学与工程前沿（英文）》 2019年 第13卷 第2期 doi: 10.1007/s11783-019-1105-8

摘要：

Four NF membranes were compared regarding arsenate rejection and their properties.

Rejection of arsenate had no relationship with membrane pore size.

A more negative surface charge was favorable for arsenate rejection at neutral pH.

A severe membrane fouling could lead to a great reduction of arsenic rejection.

关键词： Arsenate     Nanofiltration     Drinking water     Membrane property     Membrane fouling    

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Structure creation in earthen construction materials: information from dry soil mixtures

Christopher BECKETT, Charles AUGARDE

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 151-159 doi: 10.1007/s11709-011-0109-7

摘要： There is increasing interest in the use of earthen construction materials, such as rammed earth, due to their inherent sustainability. These materials have been used by man for thousands of years and some of the earliest examples can be found in China. Features of the structures of these materials arise from the means of production. In particular, in situ earthen construction materials exhibit strong anisotropy due to their layered nature. A more subtle structure effect arises from the way that the earth mixture is deposited. This paper reviews and discusses stratification effects in dry soil mixtures, including some original experimental work, and indicates some links between the features of the dry mixtures and earthen construction materials. Improved understanding of the physical processes in play will allow more accurate specification of these materials in the future, and hence spread their use.

关键词： rammed earth     stratification     particle size distribution     pore size distribution    

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Coupling the porous conditional moment closure with the random pore model: applications to gasification

D. N. SAULOV, C. R. CHODANKA, M. J. CLEARY, A. Y. KLIMENKO

《化学科学与工程前沿（英文）》 2012年 第6卷 第1期   页码 84-93 doi: 10.1007/s11705-011-1164-2

摘要： Gasification of coal or biomass with in situ CO capture simultaneously allows production of clean hydrogen at relatively low cost and reduced emission of CO into the atmosphere. Clearly, this technology has a great potential for a future carbon constrained economy. Therefore, the development of a comprehensive, physically-based gasifier model is important. The sub-models that describe reactive transport processes in coal particles as well as in particles of CO sorbent material are among the key sub-models, which provide a necessary input for an overall gasifier model. Both coal and sorbent are materials that have complicated pore structures. The porous conditional moment closure (PCMC) model proves to be adequate for modeling reactive transport through porous media with fixed pore structure. Consumption of coal in the heterogeneous gasification reaction, however, widens the pores and reduces the surface area available for this reaction. At the same time, formation of a carbonate layer narrows the pores in the sorbent material and reduces the reaction rate of CO sorption. In both cases the pore structures are affected. Such changes are not taken into account in the existing PCMC model. In this study, we obtain the parameters of the diffusive tracer distribution based on the pore size distribution given by the widely applied random pore model (RPM), while coupling PCMC with RPM. Such coupling allows taking into account changes in pore structure caused by heterogeneous reactions and thus improves the accuracy of these key sub-models.

关键词： gasification     CO2 capture     PCMC     RPM    

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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when hr/D > 0.5. For a tunnel with hr/D ≤ 0.5, the variation of hr/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change     deviation correction trajectory     earth pressure balance shield     mechanical model     posture rectification    

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Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

《能源前沿（英文）》 2008年 第2卷 第1期   页码 116-120 doi: 10.1007/s11708-008-0019-0

摘要： A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward. To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion is stable, however, it will fluctuate much when the combustion is unstable.

关键词： comparison     wavelet approximation     pressure transducer     general pressure     consistent    

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标题 作者 时间 类型 操作

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

期刊论文

Analyzing the characterization of pore structures and permeability of diesel contaminated clays under

期刊论文

Catalyst particle shapes and pore structure engineering for hydrodesulfurization and hydrodenitrogenation

期刊论文

Uncoupled state space solution to layered poroelastic medium with anisotropic permeability and compressible pore

Zhiyong AI, Wenze ZENG, Yichong CHENG, Chao WU

期刊论文

Influence of pore structure on biologically activated carbon performance and biofilm microbial characteristics

期刊论文

Effect of catalyst layer mesoscopic pore-morphology on cold start process of PEM fuel cells

Ahmed Mohmed DAFALLA, Fangming JIANG

期刊论文

Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated undrained stress paths

Mingjing JIANG, Haijun HU, Jianbing PENG, Serge LEROUEIL

期刊论文

polybenzoxazine-based carbon microspheres with nitrogen functionalities: Effects of mixed solvents on pore

Uthen Thubsuang, Suphawadee Chotirut, Apisit Thongnok, Archw Promraksa, Mudtorlep Nisoa, Nicharat Manmuanpom, Sujitra Wongkasemjit, Thanyalak Chaisuwan

期刊论文

Applications of atomic force microscopy in immunology

Jiping Li, Yuying Liu, Yidong Yuan, Bo Huang

期刊论文

Pore-scale simulation of water/oil displacement in a water-wet channel

Jin Zhao, Guice Yao, Dongsheng Wen

期刊论文

Influence of pore size and membrane surface properties on arsenic removal by nanofiltration membranes

Nathalie Tanne, Rui Xu, Mingyue Zhou, Pan Zhang, Xiaomao Wang, Xianghua Wen

期刊论文

Structure creation in earthen construction materials: information from dry soil mixtures

Christopher BECKETT, Charles AUGARDE

期刊论文

Coupling the porous conditional moment closure with the random pore model: applications to gasification

D. N. SAULOV, C. R. CHODANKA, M. J. CLEARY, A. Y. KLIMENKO

期刊论文

Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

期刊论文

Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

期刊论文