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期刊论文 37

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge     aerodynamics     nonlinear     aeroelastic model     Pseudo-steady     mean wind loads    

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Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要： The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词： adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

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Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 56-66 doi: 10.1007/s11709-008-0001-2

摘要： Present paper deals with the computing of passive earth pressure acting on the vertical rigid retaining wall supporting the soil mass subjected to water seepage. The basic assumptions of Coulomb’s theory and the 2-dimensional steady flow function are used. Three Coulomb-type solutions for the passive earth pressures are presented for the walls provided with three different drainage systems respectively. Based on the general solutions, the variations of the critical inclination of the failure surface and the coefficient of passive earth pressure with increasing the effective friction angle of the soil mass, the soil/structure friction angle, and the water/soil unit weight ratio are discussed. Two tables with values of the coefficients of passive earth pressure for Cases 1 and 3 respectively are also presented.

关键词： function     coefficient     Coulomb-type     effective friction     different drainage    

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Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 26-34 doi: 10.1007/s11705-007-0006-8

摘要： The effect of steady shear on multi-axial texture of symmetric diblock copolymer was investigated by using dynamic density functional theory. Through modifying the periodic boundary condition, the parallel-transverse biaxial texture and perpendicular-parallel-transverse triaxial texture have been observed. In the formation of the multi-axial texture, there are two critical velocities μ and µ, at which the transition between the perpendicular and the parallel lamellar morphology, and the transition between the parallel and the transverse lamellar morphology occur, respectively. The two critical velocities increase as the interaction parameter increases, but they almost remain constant at different shear rates. Furthermore, the rotation from the transverse lamellae to the parallel lamellae induced by the shear strain, and the increase of lamellar spacings of the three lamellae after removing the shear, have also been observed by the time evolution of the morphologies. These phenomena are consistent with experimental work.
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Automated synthesis of steady-state continuous processes using reinforcement learning

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 288-302 doi: 10.1007/s11705-021-2055-9

摘要： Automated flowsheet synthesis is an important field in computer-aided process engineering. The present work demonstrates how reinforcement learning can be used for automated flowsheet synthesis without any heuristics or prior knowledge of conceptual design. The environment consists of a steady-state flowsheet simulator that contains all physical knowledge. An agent is trained to take discrete actions and sequentially build up flowsheets that solve a given process problem. A novel method named SynGameZero is developed to ensure good exploration schemes in the complex problem. Therein, flowsheet synthesis is modelled as a game of two competing players. The agent plays this game against itself during training and consists of an artificial neural network and a tree search for forward planning. The method is applied successfully to a reaction-distillation process in a quaternary system.

关键词： automated process synthesis     flowsheet synthesis     artificial intelligence     machine learning     reinforcement learning    

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New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1492-1508 doi: 10.1007/s11709-020-0679-3

摘要： Natural slopes consist of non-homogeneous soil profiles with distinct characteristics from slopes made of homogeneous soil. In this study, the limit equilibrium modified pseudo-dynamic method is used to analyze the stability of two-layered soil slopes in which the failure surface is assumed to be a logarithmic spiral. The zero-stress boundary condition at the ground surface under the seismic loading condition is satisfied. New formulations derived from an analytical method are proposed for the predicting the seismic response in two-layered soil. A detailed parametric study was performed in which various parameters (seismic accelerations, damping, cohesion, and angle of internal friction) were varied. The results of the present method were compared with those in the available literature. The present analytical analysis was also verified against the finite element analysis results.

关键词： layered soil     limit equilibrium method     seismic analysis     damping     PLAXIS    

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导航卫星双向伪距时间同步

谭述森

《中国工程科学》 2006年 第8卷 第12期   页码 70-74

摘要：

针对卫星导航系统时间同步需求，提出了导航卫星双向伪距时间同步的理论根据，并就4种基本同步方法（双向无线电伪距同步方法, 星地双向激光伪距同步方法,双向卫星中继无线电伪距同步方法, 双向地球站中继无线电伪距同步方法）与应用进行了分析，与目前国际导航卫星时间同步通用方法相比,具有精度高, 方法简单，设备负担轻特点。

关键词： 导航卫星     伪距     时间同步    

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Modeling and analysis of steady-state vibration induced by backlash in servo rotary table

Xiao YANG,Dun LU,Sanli LIU,Jun ZHANG,Wanhua ZHAO

《机械工程前沿（英文）》 2015年 第10卷 第1期   页码 43-47 doi: 10.1007/s11465-015-0327-0

摘要：

Backlash cannot be always avoided in mechanical systems because of wear or looseness. Steady-state vibration may be induced by backlash in closed loop feed drive systems. This paper presents a mathematical model of a servo rotary table, considering the effect of backlash. The accuracy of this model is verified by an experiment. The influences of the parameters, such as position controller gain, velocity controller gain, load and the magnitude of backlash, on steady-state vibration are discussed. The steady-state vibration amplitude increases with the position controller gain, load and the magnitude of backlash. The steady-state vibration frequency increases with the position controller gain and the velocity controller gain, while an increase in load leads to a decrease in the frequency.

关键词： backlash     servo rotary table     steady-state vibration    

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The construction of pseudo-Janus silica/surfactant assembly and their application to stabilize Pickering

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1101-1113 doi: 10.1007/s11705-021-2095-1

摘要： Nanoparticles with high surface energy and chemical activity have drawn substantial attention in petroleum industry. Recently, Janus nanoparticles exhibited tremendous potential in enhanced oil recovery (EOR) due to their asymmetric structures and properties. In this study, a series of amphiphilic pseudo-Janus@OTAB (PJ@C18) nanoparticles with different concentrations of stearyltrimethylammoium bromide (OTAB) were successfully fabricated. The structures and properties of PJ@C18 were characterized by Fourier transform infrared spectroscopy and ζ-potential measurements. Based on the emulsification experimental results, the interaction models and the self-assembly behavior between hydrophilic nanoparticles (SiO2@NH2) and OTAB molecules at the oil/water interface were proposed, which was further confirmed via the measurements of the contact angle and dynamic interfacial tension. Interestingly, it was found that the change of pH value from 7.5 to 4.0 caused the type reversal of the PJ@C18-1000 stabilized Pickering emulsions. Furthermore, the PJ@C18-1000 stabilized Pickering emulsion system with excellent salt and temperature tolerances (10000 mg∙L–1, 90 °C) significantly improved the oil recovery in the single-tube (more than 17%) and double-tube (more than 25%) sand pack model flooding tests. The findings of this study could help to better understand the construction mechanism of pseudo-Janus silica/surfactant assembly and the potential application of PJ@C18-1000 stabilized Pickering emulsions for EOR.

关键词： Janus nanoparticles     surfactant     double phase inversion     self-assembly     enhanced oil recovery    

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Micromechanics model for static and dynamic strength of concrete under confinement

ZHENG Dan

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 329-335 doi: 10.1007/s11709-008-0044-4

摘要： The process of propagation, kinking of micro-cracks in concrete and the interaction among cracks as well as the induced failure were analyzed using the model that describes the wing type crack from the point of view of micromechanics. The pseudo-force method is applied to calculate the compressive strength factor of kinky propagated crack taking into account the effect of interaction among cracks. On the assumption that the micro fracture toughness of concrete does not vary with stain rate, the static and dynamic strength of concrete under different confinements can be calculated. The comparison of calculation result with experimental data indicates that a good agreement is achieved which implies that the model can be used to explain the rate-dependent properties of concrete in multi-axial stress state.

关键词： comparison     different     interaction     pseudo-force     toughness    

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Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation

Veena Bangalore Rangappa, Vidya Shetty Kodialbail, Saidutta Malur Bharthaiyengar

《环境科学与工程前沿（英文）》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0863-9

摘要： Continuous pulsed plate bioreactor (PPBR) was used for phenol biodegradation. cells immobilized on granular activated carbon was used. Dynamic and steady state biofilm characteristics depend on dilution rate (DR). Lower DR favour phenol degradation and uniform, thick biofilm formation. Exo polymeric substance production in biofilm are favoured at lower dilution rates. Pulsed plate bioreactor (PPBR) is a biofilm reactor which has been proven to be very efficient in phenol biodegradation. The present paper reports the studies on the effect of dilution rate on the physical, chemical and morphological characteristics of biofilms formed by the cells of Pseudomonas desmolyticum on granular activated carbon (GAC) in PPBR during biodegradation of phenol. The percentage degradation of phenol decreased from 99% to 73% with an increase in dilution rate from 0.33 h?1 to 0.99 h?1 showing that residence time in the reactor governs the phenol removal efficiency rather than the external mass transfer limitations. Lower dilution rates favor higher production of biomass, extracellular polymeric substances (EPS) as well as the protein, carbohydrate and humic substances content of EPS. Increase in dilution rate leads to decrease in biofilm thickness, biofilm dry density, and attached dry biomass, transforming the biofilm from dense, smooth compact structure to a rough and patchy structure. Thus, the performance of PPBR in terms of dynamic and steady-state biofilm characteristics associated with phenol biodegradation is a strong function of dilution rate. Operation of PPBR at lower dilution rates is recommended for continuous biologic treatment of wastewaters for phenol removal.

关键词： Biofilm     Exopolymeric substances     Phenol     Dilution rate     Pulsed plate bioreactor    

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Electrocoagulation process for the treatment of metal-plating wastewater: Kinetic modeling and energy consumption

Fatih Ilhan, Kubra Ulucan-Altuntas, Yasar Avsar, Ugur Kurt, Arslan Saral

《环境科学与工程前沿（英文）》 2019年 第13卷 第5期 doi: 10.1007/s11783-019-1152-1

摘要： The wastewater from industrial area was treated by EC via Fe and Al electrodes. Cu, Ni, Cr and Zn were highly removed at the first minutes, simultaneously. Pseudo-2nd-order was found to be more suitable for kinetics. Adsorption capacities based on kinetic modeling were observed as Cr>Cu>Ni>Zn. The chemical cost in the case of pH adjustment after EC was less as 3.83 $/m3. It is known that wastewater produced by the metal-plating industry contains several heavy metals, which are acidic in nature and therefore toxic for the environment and for living creatures. In particular, heavy metals enter the food chain and accumulate in vital organs and cause serious illness. The precipitation of these metals is mostly achieved by pH adjustment, but as an alternative to this method, the electrocoagulation process has investigated in this study using iron and aluminum electrodes. The effects of the pH adjustment on removal before and after the electrocoagulation process were investigated, and cost analyses were also compared. It was observed that a high proportion of removal was obtained during the first minutes of the electrocoagulation process; thus, the current density did not have a great effect. In addition, the pH adjustment after the electrocoagulation process using iron electrodes, which are 10% more effective than aluminum electrodes, was found to be much more efficient than before the electrocoagulation process. In the process where kinetic modeling was applied, it was observed that the heavy metal removal mechanism was not solely due to the collapse of heavy metals at high pH values, and with this modeling, it was seen that this mechanism involved adsorption by iron and aluminum hydroxides formed during the electrocoagulation process. When comparing the ability of heavy metals to be adsorbed, the sequence was observed to be Cr>Cu>Ni>Zn, respectively.

关键词： Electrochemical treatment     Heavy metals     Kinetic modeling     Pseudo first order kinetic     Pseudo second order kinetic    

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Mechanical and geometric advantages in compliant mechanism optimization

Michael Yu WANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 229-241 doi: 10.1007/s11465-009-0066-1

摘要： This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formulations of compliant mechanisms posed as a topology optimization problem. With a linear elastic structural analysis, we quantify mechanical (and geometric) advantage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formulations.

关键词： compliant mechanisms     topology optimization     mechanical advantage     pseudo rigid-body mechanisms    

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Development of a steady thermal-hydraulic analysis code for the China Advanced Research Reactor

TIAN Wenxi, QIU Suizheng, GUO Yun, SU Guanghui, JIA Dounan, LIU Tiancai, ZHANG Jianwei

《能源前沿（英文）》 2007年 第1卷 第2期   页码 189-194 doi: 10.1007/s00000-007-0024-8

摘要： A multi-channel model steady-state thermal-hydraulic analysis code was developed for the China Advanced Research Reactor (CARR). By simulating the whole reactor core, the detailed mass flow distribution in the core was obtained. The result shows that structure size plays the most important role in mass flow distribution, and the influence of core power could be neglected under single-phase flow. The temperature field of the fuel element under unsymmetrical cooling condition was also obtained, which is necessary for further study such as stress analysis, etc. of the fuel element. At the same time, considering the hot channel effect including engineering factor and nuclear factor, calculation of the mean and hot channel was carried out and it is proved that all thermal-hydraulic parameters satisfy the Safety design regulation of CARR .

关键词： detailed     calculation     unsymmetrical     temperature     channel    

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城市给水管网恒定流和瞬变流数学模型研究

汪守东,沈永明,姜恒志

《中国工程科学》 2007年 第9卷 第12期   页码 26-30

摘要：

首先基于节点方程法，建立了给水管网恒定流数学模型，并采用经改进的牛顿迭代法实现了对模型的求解；其次由特征线法建立了给水管网瞬变流数学模型，可预测管网运行中出现的有害水击，并求得可能出现的最大(最小)水压及其相应发生的位置。实例研究表明，建立的模型是可靠的，且具有计算速度快、精度高等优点，可以用于城市给水管网的水力平衡数值模拟研究和为设计者防护水击所采取的措施提供理论依据。

关键词： 给水管网     恒定流     瞬变流     水击     牛顿迭代法    

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标题 作者 时间 类型 操作

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

期刊论文

Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

期刊论文

Automated synthesis of steady-state continuous processes using reinforcement learning

期刊论文

New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

期刊论文

导航卫星双向伪距时间同步

谭述森

期刊论文

Modeling and analysis of steady-state vibration induced by backlash in servo rotary table

Xiao YANG,Dun LU,Sanli LIU,Jun ZHANG,Wanhua ZHAO

期刊论文

The construction of pseudo-Janus silica/surfactant assembly and their application to stabilize Pickering

期刊论文

Micromechanics model for static and dynamic strength of concrete under confinement

ZHENG Dan

期刊论文

Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation

Veena Bangalore Rangappa, Vidya Shetty Kodialbail, Saidutta Malur Bharthaiyengar

期刊论文

Electrocoagulation process for the treatment of metal-plating wastewater: Kinetic modeling and energy consumption

Fatih Ilhan, Kubra Ulucan-Altuntas, Yasar Avsar, Ugur Kurt, Arslan Saral

期刊论文

Mechanical and geometric advantages in compliant mechanism optimization

Michael Yu WANG

期刊论文

Development of a steady thermal-hydraulic analysis code for the China Advanced Research Reactor

TIAN Wenxi, QIU Suizheng, GUO Yun, SU Guanghui, JIA Dounan, LIU Tiancai, ZHANG Jianwei

期刊论文

城市给水管网恒定流和瞬变流数学模型研究

汪守东,沈永明,姜恒志

期刊论文