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Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 11-23 doi: 10.1007/s11709-010-0081-7

摘要： Macroscopic modeling of soils is based on a number of properties that refer to the mesoscopic morphology. The most fundamental parameters of this art are: 1) coupling parameters between partial stresses of components and deformations of components, 2) porosities, 3) saturation, and 4) permeability and diffusivity, tortuosity. The main aim of this paper is to present in juxtaposition continuous one-, two-, and three-component models of geomaterials appearing in construction of embankment dams. In particular, the above mentioned features, especially saturation with water and seepage problems, modeling of fluidization yielding piping, and generalizations of the Darcy law and changes of porosity, are presented.

关键词： thermomechanical modeling     soil morphology     saturation     porosity    

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Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 235-240 doi: 10.1007/s11465-017-0458-6

摘要： We describe the formation of nested wrinkles created by the thermal mismatch between a narrow-band thin film and a compliant substrate. When a film is described as “narrow-band”, it literally means that the film band width is much shorter than its length; more precisely, it means that the width is comparable with the wavelength of the wrinkles. A silicon mask was used during film sputtering to create narrow-band films on poly (dimethylsiloxane) substrate, thus creating regular boundaries to steer local stresses and control wrinkle morphology. Disordered nano-scale wrinkles were found nested within highly ordered micro-scale sinusoidal wrinkles. The formation of nested wrinkles was explained through the amplitude and wavelength saturation of nano-scale wrinkles. The disordered morphology of nano-scale wrinkles and the highly ordered morphology of micro-scale wrinkles were explained by using the boundary effect.

关键词： nested and hierarchical wrinkles     morphology     amplitude saturation     boundary effect    

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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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Effects of metal ions on the morphology of calcium sulfate hemihydrate whiskers by hydrothermal method

Tianjie Liu, Hao Fan, Yanxia Xu, Xingfu Song, Jianguo Yu

《化学科学与工程前沿（英文）》 2017年 第11卷 第4期   页码 545-553 doi: 10.1007/s11705-017-1665-8

摘要： The effects of Na , Mg , Al and Fe ion concentrations on the crystal morphology of calcium sulfate hemihydrate whiskers formed via a hydrothermal method have been studied. In the presence of Al concentrations higher than 1×10 mol/L the whiskers were significantly shorter and thicker and the presence of Mg and Fe resulted in shorter whiskers. The presence of Na did not affect the morphology of the whiskers. Through elemental analysis, it was determined that Mg and Al were selectively adsorbed on the surfaces of the crystals, whereas Fe underwent a hydrolysis reaction to form a brown precipitate which decreased the ion concentration in the solution. These results indicate that in raw materials used for the industrial preparation of calcium sulfate whiskers, Al and Fe should be removed and the Mg concentration should be less than 8 × 10 mol/L in order to obtain pure whiskers with high aspect ratios.

关键词： metal ions     morphology     calcium sulfate hemihydrate whiskers     hydrothermal method     selective adsorption    

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Molecular level simulations on multi-component systems —a morphology prediction method

C. SCHMIDT, J. ULRICH

《化学科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 49-54 doi: 10.1007/s11705-013-1307-8

摘要： The crystal morphology grown from a solution composed of an organic solvent, solute and additive can be predicted reliably by a computational method. Modeling the supersaturated solution as liquid phase is achieved by employing commercial software. The molecular composition of this solution is a required input parameter. The face specific diffusion coefficient of the solid (crystal surface) and liquid (solution) system is determined using the molecular dynamics procedure. The obtained diffusion coefficient is related to the specific face growth rate via the attachment energy of the pure morphology. The significant improvements are achieved in the morphology prediction because the investigation on the face growth rates in a complex growth environment (as multi-component solutions with additives) can be carried out based on the diffusion coefficients.

关键词： crystallization     morphology     molecular dynamics     solution    

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Comprehensive kinetostatic modeling and morphology characterization of cable-driven continuum robots

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0756-0

摘要： In-situ maintenance is of great significance for improving the efficiency and ensuring the safety of aero-engines. The cable-driven continuum robot (CDCR) with twin-pivot compliant mechanisms, which is enabled with flexible deformation capability and confined space accessibility, has emerged as a novel tool that aims to promote the development of intelligence and efficiency for in-situ aero-engine maintenance. The high-fidelity model that describes the kinematic and morphology of CDCR lays the foundation for the accurate operation and control for in-situ maintenance. However, this model was not well addressed in previous literature. In this study, a general kinetostatic modeling and morphology characterization methodology that comprehensively contains the effects of cable-hole friction, gravity, and payloads is proposed for the CDCR with twin-pivot compliant mechanisms. First, a novel cable-hole friction model with the variable friction coefficient and adaptive friction direction criterion is proposed through structure optimization and kinematic parameter analysis. Second, the cable-hole friction, all-component gravities, deflection-induced center-of-gravity shift of compliant joints, and payloads are all considered to deduce a comprehensive kinetostatic model enabled with the capacity of accurate morphology characterization for CDCR. Finally, a compact continuum robot system is integrated to experimentally validate the proposed kinetostatic model and the concept of in-situ aero-engine maintenance. Results indicate that the proposed model precisely predicts the morphology of CDCR and outperforms conventional models. The compact continuum robot system could be considered a novel solution to perform in-situ maintenance tasks of aero-engines in an invasive manner.

关键词： kinetostatic modeling     morphology characterization     variable friction     continuum robots     in-situ maintenance    

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The effect of sea level rise on beach morphology of caspian sea coast

M. A. Lashteh NESHAEI, F. GHANBARPOUR

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 369-379 doi: 10.1007/s11709-017-0398-6

摘要： Study of beach morphology has been one of the most important issues in coastal engineering research projects. Because of the existence of two important coastal areas located in the north and south parts of the Iran, in the present study an analysis of the coastal zone behaviour is made. Bed level elevations are measured and compared with the theoretical equilibrium profile. It is shown that the behaviour of the coastal zone in the region is consistent with the Dean (1991) equilibrium profile. In the next stage, following extensive investigations, the bed level changes due to arise in sea level at different locations in the surf zone are estimated. The mechanism of beach re-treatment due to a rise in sea level is considered based on the simplified model of Dean (1991) in which the mass balance of the sediments is taken into account. Comparison of the equilibrium profiles for different cases of sea level rise, clearly shows that because of the sediment transport induced by the fluctuation of the water level, the beach profile in the surf zone changes accordingly resulting in an erosion in the inner region of the surf zone and an accumulation of sediments towards the offshore.

关键词： wave     coastal zone     beach morphology     evolution     equilibrium profile     sea level rise    

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Morphology selective construction of

Maher Darwish, Ali Mohammadi, Navid Assi, Samer Abuzerr, Youssef Alahmad

《化学科学与工程前沿（英文）》 2020年 第14卷 第4期   页码 561-578 doi: 10.1007/s11705-019-1808-1

摘要： Controlled growth of Bi WO nanorods with exposed [0 0 1] facets and the fabrication of an Fe O -Bi WO magnetic composite by a microwave-assisted polyol process, were achieved in this study. The adsorptivity and photocatalytic performance of the composite toward sunset yellow dye degradation were greatly enhanced by the -cyclodextrin cavities on its surface, firmly anchored through a cetyltrimethylammonium bromide linkage. A series of examinations and characterizations were carried out to determine the influence of various factors on the morphological modulation-photocatalytic behavior of the pure Bi WO prior to final functionalization. Changing the pH of the precursor solution impacted the formation of 0D, 2D, and 3D structures; however, the presence of hexamethylenetetramine surfactant induced the development of 1D nanorod structure. A reasonable crystal growth mechanism was proposed to elucidate the formation process. Conversely, the mechanism of the activity enhancement of -cyclodextrin functionalized Fe O -Bi WO , compared to that of the non-functionalized samples, could be realized with the assistance of chemical trapping experiments on sunset yellow, and was confirmed on the colorless antibiotic (sulfamethoxazole). The high performance and durability of this composite can be attributed to the facet-dependent activity, large adsorption capacity due to inclusion interactions, enhanced visible light absorption, and efficient charge separation.

关键词： β-cyclodextrin     Bi2WO6     shape controlled     nanorod     sunset yellow    

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Additives effects on crystallization and morphology in a novel caustic aluminate solution decomposition

Ying ZHANG, Shili ZHENG, Yifei ZHANG, Hongbin XU, Yi ZHANG

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 88-92 doi: 10.1007/s11705-009-0133-5

摘要： A novel process of caustic aluminate solution decomposition by alcohol medium was developed by the Institute of Process Engineering, Chinese Academy of Sciences in order to solve the problem of low decomposition ratio in the traditional Bayer seeded hydrolysis process. In this research, effects of additives on the crystallization ratio, secondary particle size and morphology of aluminum hydroxide in the new process were studied to obtain high-quality products. On the basis of primary selection of additives, an orthogonal design L9(3 ) was used as a chemometric method to investigate the effects of additives. The studied parameters include the reaction style, quantity of additives, caustic soda concentration, as well as the combination manner. The crystallization ratios of sodium aluminate solution and crystal size of aluminum hydroxide, determined by ICP-OES, SEM and MLPSA (Malvern Laser Particle Size Analyzer), were used to evaluate the effects of the additives. The results showed that different combination manners could promote agglomeration or dispersion. An additive composed by Tween 80 and PEG 200 could promote agglomeration, while a spot of PEG species had a relatively strong dispersion effect. However, the additives had little effects on the crystallization ratios. According to the Raman spectra result, the added alcohol medium might serve as a kind of solvent.

关键词： additive     crystallization     morphology     caustic aluminate solution     aluminium hydroxide    

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Influence of coagulation bath on morphology of cellulose membranes prepared by NMMO method

LU Yangcheng, WU Yingxin

《化学科学与工程前沿（英文）》 2008年 第2卷 第2期   页码 204-208 doi: 10.1007/s11705-008-0027-y

摘要： To control the morphology of cellulose membranes used for separation, they were prepared by the NMMO method using water, methanol, ethanol and their binary solution as coagulation baths. Morphologies of the surface and cross section of dry membranes were observed. The pore structure parameters of wet membranes were determined. By comparison, the process and mechanism of pore formation in dry membranes were suggested, and the relativity of cellulose crystal size to average pore diameter in wet membranes and their influences were discussed. The results show that the morphology of dry membranes is clearly varied with coagulation baths, while the porosity of wet membranes is almost constant. Porous structures can appear in the compact region of dry membranes due to swelling from water. These pores have a virtual effect on the average pore diameter of wet membranes. By changing the composition of coagulation baths, the microstructure of cellulose membranes in a dry or wet environment can be adjusted separately.

关键词： comparison     NMMO     constant     diameter     process    

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Investigation of sediment transport pattern and beach morphology in the vicinity of submerged groyne

H. Afsoos Biria,M. A. Lashteh Neshaei,A. Ghabraei,M. A. Mehrdad

《结构与土木工程前沿（英文）》 2015年 第9卷 第1期   页码 82-90 doi: 10.1007/s11709-014-0275-5

摘要： Marine structures, such as Groynes, Sea walls and Detached Breakwaters, are constructed in coast of area to improve coast stability against bed erosions due to changing wave and current pattern. Marine mechanisms and interaction with the hydraulic structures need to be intensively studied. Groynes are one of the most prominent structures that are used in shore protection and littoral sediment. The main hydraulic function of the groyne is to control the long shore current and littoral sediment transport. This structure can be submerged and provide the necessary beach protection without negative aesthetic impact. However, for submerged structures adopted for beach protection, the shoreline response to these structures is not well understood. The objective of this study is to predict sediment transport in the vicinity of submerged groyne and comparison with non-submerged groyne focusing on a part of the coast at Dahane Sar Sefidrood, Guilan Province, Iran, where serious coast erosion has been occurred. The simulations were designed using a one-line model which can be used as a first approximation of shoreline prediction in the vicinity of groyne. The results of the proposed model are compared with experimental data to determine the shape of the coast. The results of predicted beach deformation show that when submerged groyne construct in the beach, sediment accumulation will be slightly less than the non-submerged groyne; because transfer coefficient for the submerged groyne is more than non-submerged groyne. This result will cause more sediment passing on submerged groyne. Finally, the result of the present study show that using submerged groyne is an efficient way to control the sediment and beach erosion without causing severe environmental effect on the coast.

关键词： submerged groyne     non-submerged groyne     beach morphology     Dahane Sar Sefidrood     sediment transport    

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Sulfonic acid-functionalized mesoporous silica catalyst with different morphology for biodiesel production

《化学科学与工程前沿（英文）》 2022年 第16卷 第8期   页码 1198-1210 doi: 10.1007/s11705-021-2133-z

摘要： Sulfonic acid functionalized mesoporous silica based solid acid catalysts with different morphology were designed and fabricated. The synthesized materials were characterized by various physicochemical and spectroscopic techniques like scanning electron microscope-energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area, thermogravimetric analysis and n-butylamine acidity. The shape of catalysts particles plays an important role in its activity. The sulfonic acid functionalized mesoporous silica catalysts of spherical shape and the cube shape were assessed for catalytic activity in biodiesel production. The catalytic biodiesel production reaction over the catalysts were studied by esterification of free fatty acid, oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio, catalyst amount, reaction temperature and reaction time on catalytic activity were investigated to optimize the conditions for maximum conversion. It was sulfonated cubic shape mesoporous silica which exhibited better activity as compared to the spherical shape silica catalysts. Additionally, the catalyst was regenerated and reused up to three cycles without any significant loss in activity. The present catalysts exhibit superior performance in biodiesel production and it can be used for the several biodiesel feedstock’s that are rich in free fatty acids.

关键词： solid acid catalyst     mesoporous silica     sulfonic acid     biodiesel     esterification     oleic acid    

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Influence of morphology on high-temperature rheological properties of bitumen modified with styrene-butadiene-styrene

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 806-819 doi: 10.1007/s11709-021-0731-y

摘要： Different microstructures of the same polymer-modified bitumen (PMB) were obtained by subjecting the bitumen modified with styrene-butadiene-styrene (SBS) copolymer to isothermal annealing at various temperatures. The effects of the morphology on the rheological properties of SBS-modified bitumen were investigated within the high-temperature range. The PMB microstructures were quantitatively evaluated using image analysis. A dynamic shear rheometer was used to measure the rheological parameters of the PMB samples and perform the multiple stress creep and recovery (MSCR) test. A quantitative basis could be established on which to discuss the relationship between the PMB morphology and rheology. The image analysis indicated that conditioning by isothermal annealing evidently led to a difference in the microstructure of the samples. Variation of the thermal history is demonstrated to be a practical way to vary the morphology of the PMB with the same raw materials and formulation. Compared with the two-phase morphology, the single-phase microstructure tended to have a narrower linear viscoelastic (LVE) region of the PMB. Within the LVE region, especially at low frequencies, the homogenous PMB can store more energy when experiencing loadings and is more elastic. Outside the LVE region, based on the MSCR test results, the homogenous morphology could assist in reaching a higher percentage of strain recovery after the creep period.

关键词： polymer     bitumen     microstructure     rheology     viscoelasticity    

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Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要： The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词： poly(trimethylene terephthalate)     short carbon fiber     banded spherulites     crack    

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Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste

Feneuil BLANDINE, Karin HABERMEHI-CWIRZEN, Andrzej CWIRZEN

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 255-255 doi: 10.1007/s11709-017-0395-9

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标题 作者 时间 类型 操作

Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

期刊论文

Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

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

Effects of metal ions on the morphology of calcium sulfate hemihydrate whiskers by hydrothermal method

Tianjie Liu, Hao Fan, Yanxia Xu, Xingfu Song, Jianguo Yu

期刊论文

Molecular level simulations on multi-component systems —a morphology prediction method

C. SCHMIDT, J. ULRICH

期刊论文

Comprehensive kinetostatic modeling and morphology characterization of cable-driven continuum robots

期刊论文

The effect of sea level rise on beach morphology of caspian sea coast

M. A. Lashteh NESHAEI, F. GHANBARPOUR

期刊论文

Morphology selective construction of

Maher Darwish, Ali Mohammadi, Navid Assi, Samer Abuzerr, Youssef Alahmad

期刊论文

Additives effects on crystallization and morphology in a novel caustic aluminate solution decomposition

Ying ZHANG, Shili ZHENG, Yifei ZHANG, Hongbin XU, Yi ZHANG

期刊论文

Influence of coagulation bath on morphology of cellulose membranes prepared by NMMO method

LU Yangcheng, WU Yingxin

期刊论文

Investigation of sediment transport pattern and beach morphology in the vicinity of submerged groyne

H. Afsoos Biria,M. A. Lashteh Neshaei,A. Ghabraei,M. A. Mehrdad

期刊论文

Sulfonic acid-functionalized mesoporous silica catalyst with different morphology for biodiesel production

期刊论文

Influence of morphology on high-temperature rheological properties of bitumen modified with styrene-butadiene-styrene

期刊论文

Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

期刊论文

Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste

Feneuil BLANDINE, Karin HABERMEHI-CWIRZEN, Andrzej CWIRZEN

期刊论文