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Stress-strain relationship with soil structural parameters of collapse loess

SHAO Shengjun, LONG Jiyong, YU Qinggao

《结构与土木工程前沿（英文）》 2008年 第2卷 第2期   页码 151-160 doi: 10.1007/s11709-008-0020-z

摘要： Through the tri-axial shearing tests of unsaturated intact loess and based on the concept of comprehensive soil structural potential, this paper reveals the changing laws of soil structural property under the tri-axial stress conditions and establishes a mathematical expression equation of structural parameters, whereby reflecting the effects of unsaturated loess water content, stress and strain states, which is introduced into the shearing stress and shearing strain relation to obtain the structural stress-strain relation. The tests reveal that the loess dilatancy is of shearing contraction and shearing expansion, whereby indicating that there is a good linear relation between the stress ratio and shearing expansion strain ratio. The larger consolidation confining pressure is, the larger the stress of shearing contraction and expansion critical point is; and the larger water content is, the smaller the strain ratio of shearing contraction and expansion critical point is. Finally, the constitutive model is established to reflect the variation in loess structure, stress-strain softening and hardening, and shearing contraction and shearing expansion features. Through the comparative analysis, the stress-strain curves described by the constitutive relationship are found to be in good conformity with test results, whereby testing the rationality of the model in this paper.

关键词： hardening     shearing expansion     unsaturated     structural property     mathematical expression    

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A computational toolbox for molecular property prediction based on quantum mechanics and quantitativestructure-property relationship

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 152-167 doi: 10.1007/s11705-021-2060-z

摘要： Chemical industry is always seeking opportunities to efficiently and economically convert raw materials to commodity chemicals and higher value-added chemical-based products. The life cycles of chemical products involve the procedures of conceptual product designs, experimental investigations, sustainable manufactures through appropriate chemical processes and waste disposals. During these periods, one of the most important keys is the molecular property prediction models associating molecular structures with product properties. In this paper, a framework combining quantum mechanics and quantitative structure-property relationship is established for fast molecular property predictions, such as activity coefficient, and so forth. The workflow of framework consists of three steps. In the first step, a database is created for collections of basic molecular information; in the second step, quantum mechanics-based calculations are performed to predict quantum mechanics-based/derived molecular properties (pseudo experimental data), which are stored in a database and further provided for the developments of quantitative structure-property relationship methods for fast predictions of properties in the third step. The whole framework has been carried out within a molecular property prediction toolbox. Two case studies highlighting different aspects of the toolbox involving the predictions of heats of reaction and solid-liquid phase equilibriums are presented.

关键词： molecular property     quantum mechanics     quantitative structure-property relationship     heat of reaction     solid-liquid phase equilibrium    

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Convective heat transfer in helical coils for constant-property and variable-property flows with high

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

《能源前沿（英文）》 2010年 第4卷 第4期   页码 546-552 doi: 10.1007/s11708-010-0116-8

摘要： Forced convection heat transfer of single-phase water in helical coils was experimentally studied. The testing section was constructed from a stainless steel round tube with an inner diameter of 10 mm, coil diameter of 300 mm, and pitch of 50 mm. The experiments were conducted over a wide Reynolds number range of 40000 to 500000. Both constant-property flows at normal pressure and variable-property flows at supercritical pressure were investigated. The contribution of secondary flow in the helical coil to heat transfer was gradually suppressed with increasing Reynolds number. Hence, heat transfer coefficients of the helical tube were close to those of the straight tube under the same flow conditions when the Reynolds number is large enough. Based on the experimental data, heat transfer correlations for both incompressible flows and supercritical fluid flows through helical coils were proposed.

关键词： convective heat transfer     helical coils     high Reynolds number     supercritical pressure     variable property    

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A review on the application of nanofluids in enhanced oil recovery

《化学科学与工程前沿（英文）》 2022年 第16卷 第8期   页码 1165-1197 doi: 10.1007/s11705-021-2120-4

摘要： Enhanced oil recovery (EOR) has been widely used to recover residual oil after the primary or secondary oil recovery processes. Compared to conventional methods, chemical EOR has demonstrated high oil recovery and low operational costs. Nanofluids have received extensive attention owing to their advantages of low cost, high oil recovery, and wide applicability. In recent years, nanofluids have been widely used in EOR processes. Moreover, several studies have focused on the role of nanofluids in the nanofluid EOR (N-EOR) process. However, the mechanisms related to N-EOR are unclear, and several of the mechanisms established are chaotic and contradictory. This review was conducted by considering heavy oil molecules/particle/surface micromechanics; nanofluid-assisted EOR methods; multiscale, multiphase pore/core displacement experiments; and multiphase flow fluid-solid coupling simulations. Nanofluids can alter the wettability of minerals (particle/surface micromechanics), oil/water interfacial tension (heavy oil molecules/water micromechanics), and structural disjoining pressure (heavy oil molecules/particle/surface micromechanics). They can also cause viscosity reduction (micromechanics of heavy oil molecules). Nanofoam technology, nanoemulsion technology, and injected fluids were used during the EOR process. The mechanism of N-EOR is based on the nanoparticle adsorption effect. Nanoparticles can be adsorbed on mineral surfaces and alter the wettability of minerals from oil-wet to water-wet conditions. Nanoparticles can also be adsorbed on the oil/water surface, which alters the oil/water interfacial tension, resulting in the formation of emulsions. Asphaltenes are also adsorbed on the surface of nanoparticles, which reduces the asphaltene content in heavy oil, resulting in a decrease in the viscosity of oil, which helps in oil recovery. In previous studies, most researchers only focused on the results, and the nanoparticle adsorption properties have been ignored. This review presents the relationship between the adsorption properties of nanoparticles and the N-EOR mechanisms. The nanofluid behaviour during a multiphase core displacement process is also discussed, and the corresponding simulation is analysed. Finally, potential mechanisms and future directions of N-EOR are proposed. The findings of this study can further the understanding of N-EOR mechanisms from the perspective of heavy oil molecules/particle/surface micromechanics, as well as clarify the role of nanofluids in multiphase core displacement experiments and simulations. This review also presents limitations and bottlenecks, guiding researchers to develop methods to synthesise novel nanoparticles and conduct further research.

关键词： nanofluid     EOR mechanism     nanoparticle adsorption     interface property     internal property    

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Experimental study on compaction-induced anisotropic mechanical property of rockfill material

Xiangtao ZHANG, Yizhao GAO, Yuan WANG, Yu-zhen YU, Xun SUN

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 109-123 doi: 10.1007/s11709-021-0693-0

摘要： The anisotropy of rockfill materials has a significant influence on the performance of engineering structures. However, relevant research data are very limited, because of the difficulty with preparing specimens with different inclination angles using traditional methods. Furthermore, the anisotropy test of rockfill materials is complex and complicated, especially for triaxial tests, in which the major principal stress plane intersects with the compaction plane at different angles. In this study, the geometric characteristics of a typical particle fraction consisting of a specific rockfill material were statistically investigated, and the distribution characteristics of particle orientation in specimens prepared via different compaction methods were examined. For high-density rockfill materials, a set of specimen preparation devices for inclined compaction planes was developed, and a series of conventional triaxial compression tests with different principal stress direction angles were conducted. The results reveal that the principal stress direction angle has a significant effect on the modulus, shear strength, and dilatancy of the compacted rockfill materials. Analysis of the relationship between the principal stress direction angles, change in the stress state, and change in the corresponding dominant shear plane shows that the angle between the compacted surface and dominant shear plane is closely related to interlocking resistance associated with the particle orientation. In addition, different principal stress direction angles can change the extent of the particle interlocking effect, causing the specimen to exhibit different degrees of anisotropy.

关键词： rockfill     inclination of specimen preparation     anisotropy     mechanical property     mechanism    

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Experimental research on the mechanical property of prestressing steel wire during and after heating

ZHENG Wenzhong, HU Qiong, ZHANG Haoyu

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 247-254 doi: 10.1007/s11709-007-0031-1

摘要： The mechanical property of prestressing steel wire during and after heating is the key factor in the design of fire resistance and after-fire damage evaluation of prestressed structures. Tensile experiment of 16 prestressing steel wires ( = 1770 N/mm, = 5 mm, low relaxation of stress) at high temperature and tensile experiment of 14 prestressed steel wires after heating are carried out. According to the experiment, the shapes of stress-strain curves of steel wire at high temperature go smooth and the mechanical property indexes of the steel wire such as strength, modulus of elasticity, etc., degenerate continuously as temperature increased. According to the experiment after heating, the mechanical property of steel wire varies little when the highest temperature that the steel wire has ever been heated to is lower than 300vH; while the stress-strain curves of steel wire become more ductile and the mechanical property indexes of the steel wire degenerate gradually when the highest temperature is higher than 300vH. By applying the theory of viscoelastic mechanics, stress-strain curves of steel wire at high temperatures without loading rate influence are obtained. The law of mechanical property indexes of the wire is presented. The mathematical models of the stress-strain relationship of the pre-stressed steel wire are established. All can serve as basic data for the analysis of fire resistance and after-fire damage evaluation of pre-stressed structures.
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深圳城市供水系统产权结构重组模式及评价

肖文,欧阳芳锐,王先甲

《中国工程科学》 2004年 第6卷 第7期   页码 48-52

摘要：

提出了城市供水系统产权结构重组的两种基本模式，运用制度经济学和管理学理论，提出产权结构模式评价的指标与方法，分析了这两种产权结构模式的特性和在这两种模式下不同利益主体的行为与利益关系的变化特点及优缺点，并提出了缓解劣势的手段与方法。

关键词： 城市供水     产权结构     产权重组     产权模式评价    

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novel strategy for the construction of silk fibroin–SiO composite aerogel with enhanced mechanical property

《化学科学与工程前沿（英文）》 2023年 第17卷 第3期   页码 288-297 doi: 10.1007/s11705-022-2222-7

摘要： The practical application of silica aerogels is an enormous challenge due to the difficulties in improving both mechanical property and thermal insulation performance. In this work, silk fibroin was used as scaffold to improve the mechanical property and thermal insulation performance of silica aerogels. The ungelled SiO2 precursor solution was impregnated into silk fibroin to prepare silk fibroin–SiO2 composite aerogels via sol−gel method followed by freeze-drying. By virtue of the interfacial hydrogen-bonding interactions and chemical reactions between silk fibroin and silica nanoparticles, SiO2 was well-dispersed in the silk fibroin aerogel and composite aerogels exhibited enhanced mechanical property. By increasing the loading of silk fibroin from 15 wt % to 21 wt %, the maximum compressive stress was enhanced from 0.266 to 0.508 MPa when the strain reached 50%. The thermal insulation performance of the composite aerogels was improved compared with pure silica aerogel, as evidenced that the thermal conductivity was decreased from 0.0668 to 0.0341 W∙m‒1∙K‒1. Moreover, the composite aerogels exhibited better hydrophobicity and fire retardancy compared to pure silica aerogel. Our work provides a novel approach to preparing silk fibroin–SiO2 composite aerogels with enhanced mechanical property and thermal insulation performance, which has potential application as thermal insulation material.

关键词： silica aerogel     silk fibroin     impregnation     thermal insulation     mechanical property    

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Meshing stiffness property and meshing status simulation of harmonic drive under transmission loading

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0674-6

摘要： The multitooth meshing state of harmonic drive (HD) is an important basic characteristic of its high transformation precision and high bearing capacity. Meshing force distribution affects the load sharing of the tooth during meshing, and theoretical research remains insufficient at present. To calculate the spatial distributed meshing forces and loading backlashes along the axial direction, an iterative algorithm and finite element model (FEM) is proposed to investigate the meshing state under varied transmission loading. The displacement formulae of meshing point under tangential force are derived according to the torsion of the flexspline cylinder and the bending of the tooth. Based on the relationship of meshing forces and circumferential displacements, meshing forces and loading backlashes in three cross-sections are calculated with the algorithm under gradually increased rotation angles of circular spline, and the results are compared with FEM. Owing to the taper deformation of the cup-shaped flexspline, the smallest initial backlash and the earliest meshing point appear in the front cross-section far from the cup bottom, and then the teeth in the middle cross-section of the tooth rim enter the meshing and carry most of the loading. Theoretical and numerical research show that the flexibility is quite different for varied meshing points and tangential force amplitude because of the change of contact status between the flexspline and the wave generator. The meshing forces and torsional stiffness of the HD are nonlinear with the torsional angle.

关键词： harmonic drive     meshing flexibility matrix     meshing force     loading backlash     flexspline     contact analysis    

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Modeling and analysis of controllable output property of cantilever-beam inertial sensors based on magnetic

Guixiong LIU, Peiqiang ZHANG, Chen XU

《机械工程前沿（英文）》 2009年 第4卷 第2期   页码 129-133 doi: 10.1007/s11465-009-0035-8

摘要： Magnetic fluid is first introduced into the traditional cantilever-beam senor. Based on the property of the cantilever-beam and the novel controllable mag-viscosity of magnetic fluid, the output of cantilever-beam sensors is under control so that the controllable output of the sensors can be realized. The mathematical model of the sensors is established and analyzed. The dynamic control function and the following educational results, which include the two curves of the displacement ratio and phase function with the different damping ratio and frequency ratio, are obtained based on the model. The result shows that it is valid to realize the controllable output of the sensors by controlling the viscosity of the magnetic fluid, and finally the expanded measurement range can be realized.

关键词： sensors     magnetic fluid     property of mag-viscosity     controllable output    

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of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative structure-property

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

《环境科学与工程前沿（英文）》 2014年 第8卷 第5期   页码 683-692 doi: 10.1007/s11783-014-0680-y

摘要： In this paper the photolysis half-lives of the model dyes in water solutions and under ultraviolet (UV) radiation were determined by using a continuous-flow spectrophotometric method. A quantitative structure-property relationship (QSPR) study was carried out using 21 descriptors based on different chemometric tools including stepwise multiple linear regression (MLR) and partial least squares (PLS) for the prediction of the photolysis half-life ( ) of dyes. For the selection of test set compounds, a K-means clustering technique was used to classify the entire data set, so that all clusters were properly represented in both training and test sets. The QSPR results obtained with these models show that in MLR-derived model, photolysis half-lives of dyes depended strongly on energy of the highest occupied molecular orbital ( ), largest electron density of an atom in the molecule ( ) and lipophilicity (log ). While in the model derived from PLS, besides aforementioned and descriptors, the molecular surface area ( ), molecular weight ( ), electronegativity ( ), energy of the second highest occupied molecular orbital ( ) and dipole moment ( ) had dominant effects on logt values of dyes. These were applicable for all classes of studied dyes (including monoazo, disazo, oxazine, sulfonephthaleins and derivatives of fluorescein). The results were also assessed for their consistency with findings from other similar studies.

关键词： dye     photolysis half-life     quantitative structure-property relationship     continuous-flow     stepwise multiple linear regression     partial least squares    

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Approximation of structural damping and input excitation force

Mohammad SALAVATI

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 244-254 doi: 10.1007/s11709-016-0371-9

摘要： Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a model-less structural input estimation are considered. The effectiveness of proposed methods has been carried out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.

关键词： structural modal parameters     damping identification method     input excitation force identification     Inverse problem    

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Preparation and property of porous hydroxyapatite as an inorganic dispersant used in suspension polymerization

XU Kaqiu, XU Jiale, WANG Yuhong

《化学科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 49-54 doi: 10.1007/s11705-008-0004-5

摘要： The porous hydroxyapatite (HAP) for suspension polymerization dispersant was prepared using calcium carbonate and phosphoric acid as raw materials. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET nitrogen adsorption. The results show that the prepared HAP has a porous structure, low particle density, large specific surface area, uniform particle size and does not agglomerate easily between the particles. The preparation conditions for the HAP were optimized as follows: solid content of calcium carbonate aqueous suspension 90 g/L, concentration of phosphoric acid 1.0 mol/L, reaction/aging temperature 50°C, and aging time 3 h. The HAP prepared under optimal preparation conditions has 106.8 m·g of specific surface area, which is about 1.5–1.8 times as much as that of Japanese HAP or commercial HAP. Its application result in the suspension polymerization of styrene show that the porous HAP dispersant has high surface activity, excellent suspension dispersibility and stability and can markedly improve the quality of polystyrene beads.

关键词： diffraction     stability     nitrogen adsorption     phosphoric     aqueous suspension    

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Preparation and property characterization of PAA/Fe3O4 nanocomposite

WEI Shanshan, ZHANG Yi, XU Jiarui

《化学科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 233-237 doi: 10.1007/s11705-007-0042-4

摘要： PAA/FeO nanocomposites were prepared by mixing nano-FeOvent. The materials were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), thermogravimetry analysis (TGA), dynamic ultra-micro hardness tester (DUMHT) and superconducting quantum interference device (SQUID) magnetometer. Results showed that PAA coordinated with nano-FeO to form a cross-linking structure. The presence of nano-FeO enhanced the thermal stability of the nanocomposite. The elasticity and hardness of the nanocomposite increased, and the indentation depth reduced with the increase of FeO content in the composites. The nanocomposites showed superparamagnetic properties at 300 K.

关键词： magnetometer     superparamagnetic     ultra-micro     thermogravimetry     transmission    

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Effects of operating conditions on membrane charge property and nanofiltration

Li XU, Li-Shun DU, Jing HE

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 492-499 doi: 10.1007/s11705-011-1143-7

摘要： The effects of the operating pressure, cross flow velocity, feed concentration, and temperature on the streaming and Zeta potential of the membranes were studied. The permeate flux and the retention rate under different nanofiltration operating conditions were also investigated. The results show that the higher pressure, feed concentration, temperature, and lower cross flow velocity lead to the higher absolute value of streaming and Zeta potential. The permeate flux of the nanofiltration decreases with the feed concentration and increases with not only the pressure but also the cross flow velocity and temperature. The higher the pressure and the cross flow velocity, the higher the retention rate. The lower feed concentration and higher temperature leads to lower retention rate. The effects of the operating conditions on the permeate flux and the retention rate were explained by the variation of the membrane charge property.

关键词： nanofiltration membrane     streaming potential     Zeta potential     permeate flux     retention rate    

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标题 作者 时间 类型 操作

Stress-strain relationship with soil structural parameters of collapse loess

SHAO Shengjun, LONG Jiyong, YU Qinggao

期刊论文

A computational toolbox for molecular property prediction based on quantum mechanics and quantitativestructure-property relationship

期刊论文

Convective heat transfer in helical coils for constant-property and variable-property flows with high

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

期刊论文

A review on the application of nanofluids in enhanced oil recovery

期刊论文

Experimental study on compaction-induced anisotropic mechanical property of rockfill material

Xiangtao ZHANG, Yizhao GAO, Yuan WANG, Yu-zhen YU, Xun SUN

期刊论文

Experimental research on the mechanical property of prestressing steel wire during and after heating

ZHENG Wenzhong, HU Qiong, ZHANG Haoyu

期刊论文

深圳城市供水系统产权结构重组模式及评价

肖文,欧阳芳锐,王先甲

期刊论文

novel strategy for the construction of silk fibroin–SiO composite aerogel with enhanced mechanical property

期刊论文

Meshing stiffness property and meshing status simulation of harmonic drive under transmission loading

期刊论文

Modeling and analysis of controllable output property of cantilever-beam inertial sensors based on magnetic

Guixiong LIU, Peiqiang ZHANG, Chen XU

期刊论文

of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative structure-property

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

期刊论文

Approximation of structural damping and input excitation force

Mohammad SALAVATI

期刊论文

Preparation and property of porous hydroxyapatite as an inorganic dispersant used in suspension polymerization

XU Kaqiu, XU Jiale, WANG Yuhong

期刊论文

Preparation and property characterization of PAA/Fe3O4 nanocomposite

WEI Shanshan, ZHANG Yi, XU Jiarui

期刊论文

Effects of operating conditions on membrane charge property and nanofiltration

Li XU, Li-Shun DU, Jing HE

期刊论文