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Application of semi-analytical finite element method to analyze the bearing capacity of asphalt pavements

Pengfei LIU, Dawei WANG, Frédéric OTTO, Markus OESER

《结构与土木工程前沿（英文）》 2018年 第12卷 第2期   页码 215-221 doi: 10.1007/s11709-017-0401-2

摘要： To facilitate long term infrastructure asset management systems, it is necessary to determine the bearing capacity of pavements. Currently it is common to conduct such measurements in a stationary manner, however the evaluation with stationary loading does not correspond to reality a tendency towards continuous and high speed measurements in recent years can be observed. The computational program SAFEM was developed with the objective of evaluating the dynamic response of asphalt under moving loads and is based on a semi-analytic element method. In this research project SAFEM is compared to commercial finite element software ABAQUS and field measurements to verify the computational accuracy. The computational accuracy of SAFEM was found to be high enough to be viable whilst boasting a computational time far shorter than ABAQUS. Thus, SAFEM appears to be a feasible approach to determine the dynamic response of pavements under dynamic loads and is a useful tool for infrastructure administrations to analyze the pavement bearing capacity.

关键词： semi-analytical finite element method     bearing capacity     asphalt pavements     moving loads     dynamic response    

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Uncertainty propagation in dynamics of composite plates: A semi-analytical non-sampling-based approach

Mahdi FAKOOR, Hadi PARVIZ

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1359-1371 doi: 10.1007/s11709-020-0658-8

摘要： In this study, the influences of spatially varying stochastic properties on free vibration analysis of composite plates were investigated via development of a new approach named the deterministic-stochastic Galerkin-based semi-analytical method. The material properties including tensile modulus, shear modulus, and density of the plate were assumed to be spatially varying and uncertain. Gaussian fields with first-order Markov kernels were utilized to define the aforementioned material properties. The stochastic fields were decomposed via application of the Karhunen-Loeve theorem. A first-order shear deformation theory was assumed, following which the displacement field was defined using admissible trigonometric modes to derive the potential and kinetic energies. The stochastic equations of motion of the plate were obtained using the variational principle. The deterministic-stochastic Galerkin-based method was utilized to find the probability space of natural frequencies, and the corresponding mode shapes of the plate were determined using a polynomial chaos approach. The proposed method significantly reduced the size of the mathematical models of the structure, which is very useful for enhancing the computational efficiency of stochastic simulations. The methodology was verified using a stochastic finite element method and the available results in literature. The sensitivity of natural frequencies and corresponding mode shapes due to the uncertainty of material properties was investigated, and the results indicated that the higher-order modes are more sensitive to uncertainty propagation in spatially varying properties.

关键词： composite plate     spatially varying stochastic properties     Galerkin method     polynomial chaos approach     semi-analytical approach    

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Improvement of the assimilable organic carbon (AOC) analytical method for reclaimed water

Xin ZHAO, Hongying HU, Shuming LIU, Feng JIANG, Xiaolei SHI, Mingtang LI, Xueqiao XU

《环境科学与工程前沿（英文）》 2013年 第7卷 第4期   页码 483-491 doi: 10.1007/s11783-013-0525-0

摘要： Microbial growth is an issue of concern that may cause hygienic and aesthetic problems during the transportation and usage of reclaimed water. Assimilable organic carbon (AOC) is an important parameter which determines the heterotrophic bacterial growth potential of water. P17 and sp. NOX are widely used to measure AOC in drinking water. The AOC values of various reclaimed water samples determined by P17 and NOX were compared with those determined by the new strains isolated from reclaimed water in this study. It showed that the conventional test strains were not suitable for AOC measurement of reclaimed water in certain cases. In addition to P17 and NOX, sp. ZJ2, G3 and sp. G6, were selected as test strains for AOC measurement of reclaimed water. Key aspects of the bioassay including inoculum cell density, incubation temperature, incubation time and the pH of samples were evaluated for the newly selected test strains. Higher inoculum density (10 CFU·mL ) and higher incubation temperature (25°C) could reduce the time required for the tests. The AOC results of various collected samples showed the advantages of the method proposed based on those five strains in evaluating the biologic stability of reclaimed water.

关键词： assimilable organic carbon (AOC)     bioassay     biological stability     reclaimed water     test bacterial strains    

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An analytical method for calculating torsional constants for arbitrary complicated thin-walled cross-sections

DU Baisong, GE Yaojun, ZHOU Zheng

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 293-297 doi: 10.1007/s11709-007-0038-7

摘要： In this paper, an analytical method is proposed for calculating torsional constants for complicated thin-walled cross-sections with arbitrary closed or open rib stiffeners. This method uses the free torsional theory and the principle of virtual work to build governing equilibrium equations involving unknown shear flows and twisting rate. After changing the form of the equations and combining these two unknowns into one, torsional function, which is a function of shear flow, shear modulus, and twisting rate, is included in the governing equations as only one of the unknowns. All the torsional functions can be easily obtained from these homogeneous linear equations, and torsional constants can be easily obtained from the torsional functions. The advantage of this method is that we can easily and directly obtain torsional constants from the torsional functions, rather than the more sophisticated shear flow and twisting rate calculations. Finally, a complicated thin-walled cross-section is given as a valid numerical example to verify the analytical method, which is much more accurate and simpler than the traditional finite element method.

关键词： homogeneous     complicated thin-walled     numerical example     advantage     torsional function    

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Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 142-149 doi: 10.1007/s11465-014-0292-z

摘要：

In recent years, prediction of the behaviors of micro and nanostructures is going to be a matter of increasing concern considering their developments and uses in various engineering fields. Since carbon nanotubes show the specific properties such as strength and special electrical behaviors, they have become the main subject in nanotechnology researches. On the grounds that the classical continuum theory cannot accurately predict the mechanical behavior of nanostructures, nonlocal elasticity theory is used to model the nanoscaled systems. In this paper, a nonlocal model for nanorods is developed, and it is used to model the carbon nanotubes with the aim of the investigating into their longitudinal vibration. Following the derivation of governing equation of nanorods and estimation of nondimensional frequencies, the effect of nonlocal parameter and the length of the nanotube on the obtained frequencies are studied. Furthermore, differential quadrature method, as a numerical solution technique, is used to study the effect of these parameters on estimated frequencies for both classical and nonlocal theories.

关键词： continuum theory     differential quadrature method     nanorod     longitudinal vibration    

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Comprehensive evaluation of heavy metal contamination of sediment in Lake Dianchi by using modified AHP method

ZHANG Yan, GAO Xiang, ZHONG Zhenyu, PENG Buzhuo, DENG Xihai

《环境科学与工程前沿（英文）》 2008年 第2卷 第3期   页码 370-379 doi: 10.1007/s11783-008-0054-4

摘要： Through the use of general sampling and measurement by Cs dating, problems regarding the absence of monitoring data can easily be resolved. Further, weighted values need to be determined while Environment Quality Comprehensive Index (EQCI) is commonly used as applied in environmental quality comprehensive evaluation. In order to overcome the subjectivity in determining weights, the modified Analytical Hierarchy Process (AHP) method was designed. The modified AHP method involved the following key procedures: First, the parameters and were calculated based on the monitoring data; second, the factors were put in order according to the symbol and value of and ; third, the continuous odd integers, which represented the importance of factors, were given to factors according to their seating order; and, fourth, the factor weights were determined from the pair-wise comparison matrix calculated by the ratio of the given odd integers. Therefore, the weights were completely based on the monitoring data. In the present study, the comprehensive quality of sediments in five sections of Lake Dianchi were evaluated and the results indicated that the current contamination of sediments in each lake section is much more serious than at any other time in history.

关键词： Dianchi     Analytical Hierarchy     monitoring     modified Analytical     importance    

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Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 361-366 doi: 10.1007/s11709-007-0048-5

摘要： The methods for constructing safe basins of ships and predicting their survival probability in random waves were studied. The nonlinear differential equation of the rolling motion of ships in random beam seas was established considering nonlinear damping, nonlinear restoring moment, and random waves. The random rolling differential equation was solved in the time domain by applying the harmonic acceleration method and by synthetically considering the instantaneous state of ships and the narrowband wave energy spectrum. The numerical simulation of random capsizing course was brought forward, the safe basins were constructed for safe navigation, and the survival probabilities of ships were calculated. As an example, the safe basins on the rolling initial value plane were constructed for a 30.27-meter-long fishing vessel according to different initial conditions and random wave parameters. The survival probabilities of the fishing vessel under different significant wave heights were predicted. Thus, the survival probabilities of ships in random seas can be predicted quantitatively by the proposed method.

关键词： different     survival probability     different significant     nonlinear differential     narrowband    

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环缝天线罩的近似分析方法 Article

罗康, 孟进, 韩江枫, 朱丹妮

《工程（英文）》 2023年 第30卷 第11期   页码 75-82 doi: 10.1016/j.eng.2023.07.015

摘要：

本文提出了一种基于近似分析方法的环缝天线罩带内和带外微波无线功率传输特性分析方法。本文的主要贡献是对环形天线罩的近似分析，推导了E平面和H平面扫描时天线罩表面入射场的统一表达式，并将环形天线罩近似分为30段直条。求解相应的60 × 60线性方程得到了沿环形带的电流分布。沿着互补槽环的磁电流是通过对偶获得的。得益于电流分布的全解析格式，使用Munk方案有效地计算了微波无线功率传输特性。以环缝双层对称混合天线罩为例，验证了该方法的准确性和有效性。HFSS和所提出的方法的CPU计算时间分别约为690 s和2.82 s。

关键词： 近似解析     环形     天线罩     基尔霍夫型电路    

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树盘干缩异向性引起应变的测算及分析

付宗营,赵景尧,蔡英春

《中国工程科学》 2014年 第16卷 第4期   页码 25-29

摘要：

研究探讨了干燥过程中树盘受抑制干缩应变、自由干缩应变、弹性应变、黏弹性蠕变应变以及机械吸附蠕变的图像解析测算法；运用该方法测算了白桦树盘常规缓慢干燥（含水率分布均匀）过程中干缩异向性引起的弦向各应变，分析了干燥过程中不同含水率阶段的应力状态及应力与各应变的关系。结果表明：应变的图像解析测算法可满足精度要求；树盘干燥至fiber saturation point( FSP)以下，弦向首先受拉伸应力作用，随着干燥的进行，拉伸应力转变为压缩应力；应力方向与各应变对应关系不同，与黏弹性蠕变应变无明显对应关系，与机械吸附蠕变基本对应。

关键词： 图像解析法     树盘     干缩异向性     干燥应力     弦向应变    

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Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

《环境科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 112-128 doi: 10.1007/s11783-008-0067-z

摘要： The purpose of this study is to present a library of analytical solutions for the three-dimensional contaminant transport in uniform flow field in porous media with the first-order decay, linear sorption, and zero-order production. The library is constructed using Green's function method (GFM) in combination with available solutions. The library covers a wide range of solutions for various conditions. The aquifer can be vertically finite, semi-infinitive or infinitive, and laterally semi-infinitive or infinitive. The geometry of the sources can be of point, line, plane or volumetric body; and the source release can be continuous, instantaneous, or by following a given function over time. Dimensionless forms of the solutions are also proposed. A computer code FlowCAS is developed to calculate the solutions. Calculated results demonstrate the correctness of the presented solutions. The library is widely applicable to solve contaminant transport problems of one- or multiple- dimensions in uniform flow fields.

关键词： solution library     contaminant transport     analytical solution     dispersion and advection     porous media     type curve     Green's function method (GFM)    

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A method of analysis for modal aero-damping of vibrating blade in incompressible flow

Jun XING, Lin LI,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 465-471 doi: 10.1007/s11708-009-0037-6

摘要： By establishing a research model for aero-damping in a uniform incoming flow, the three-dimension analytical algorithm of the modal aero-damping based on the equivalent viscous damping principle was established. The algorithm, which is suited for low-speed flow, to compute aero-damping is based on classical lift line theory in aerodynamics, according to the analytical solution of unsteady aerodynamic force. According to the analytical equations, the modal aero-damping ratio for different nature frequencies of blades in various fluid field conditions can be solved, and the factors to affect the aero-damping can be determined.The first bend and the first torsion’s modal aero-damping ratios of a compressor blade are calculated by using the above algorithms. The results show that the aero-damping cannot be neglected comparing with the structure damping. It reflects the coupling degree between the flow field and the structure field, so the aero-damping is significant to compute the stress and life of blade.

关键词： compressor     different     three-dimension analytical     classical     low-speed    

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Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 191-202 doi: 10.1007/s11465-014-0293-y

摘要：

In present study, free vibration of cracked beams resting on two-parameter elastic foundation with elastically restrained ends is considered. Euler-Bernoulli beam hypothesis has been applied and translational and rotational elastic springs in each end considered as support. The crack is modeled as a mass-less rotational spring which divides beam into two segments. After governing the equations of motion, the differential transform method (DTM) has been served to determine dimensionless frequencies and normalized mode shapes. DTM is a semi-analytical approach based on Taylor expansion series that converts differential equations to recursive algebraic equations. The DTM results for the natural frequencies in special cases are in very good agreement with results reported by well-known references. Also, the DTM procedure yields rapid convergence beside high accuracy without any frequency missing. Comprehensive studies to analyze the effects of crack location, crack severity, parameters of elastic foundation and boundary conditions on dimensionless frequencies as well as effects of elastic boundary conditions on cracked beams mode shapes are carried out and some problems handled for first time in this paper. Since this paper deals with general problem, the derived formulation has capability for analyzing free vibration of cracked beam with every boundary condition.

关键词： free vibration     cracked beam     elastic foundation     restrained ends     differential transform method    

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stability of uncertain composite plates and stochastic irregularity in their buckling mode shapes: A semi-analytical

《结构与土木工程前沿（英文）》   页码 179-190 doi: 10.1007/s11709-022-0888-z

摘要： In this study, the mechanical properties of the composite plate were considered Gaussian random fields and their effects on the buckling load and corresponding mode shapes were studied by developing a semi-analytical non-intrusive approach. The random fields were decomposed by the Karhunen−Loève method. The strains were defined based on the assumptions of the first-order and higher-order shear-deformation theories. Stochastic equations of motion were extracted using Euler–Lagrange equations. The probabilistic response space was obtained by employing the non-intrusive polynomial chaos method. Finally, the effect of spatially varying stochastic properties on the critical load of the plate and the irregularity of buckling mode shapes and their sequences were studied for the first time. Our findings showed that different shear deformation plate theories could significantly influence the reliability of thicker plates under compressive loading. It is suggested that a linear relationship exists between the mechanical properties’ variation coefficient and critical loads’ variation coefficient. Also, in modeling the plate properties as random fields, a significant stochastic irregularity is obtained in buckling mode shapes, which is crucial in practical applications.

关键词： uncertain composite plate     stochastic assume mode method     Karhunen−Loève theorem     polynomial chaos approach     plate buckling     irregularity in buckling mode shapes    

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Analytical model and finite element computation of braking torque in electromagnetic retarder

Lezhi YE,Guangzhao YANG,Desheng LI

《机械工程前沿（英文）》 2014年 第9卷 第4期   页码 368-379 doi: 10.1007/s11465-014-0314-x

摘要：

An analytical model has been developed for analyzing the braking torque in electromagnetic retarder by flux tube and armature reaction method. The magnetic field distribution in air gap, the eddy current induced in the rotor and the braking torque are calculated by the developed model. Two-dimensional and three-dimensional finite element models for retarder have also been developed. Results from the analytical model are compared with those from finite element models. The validity of these three models is checked by the comparison of the theoretical predictions and the measurements from an experimental prototype. The influencing factors of braking torque have been studied.

关键词： electromagnetic retarder     magnetic field distribution     magnetic circuit     finite element method    

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Lightweight design of an electric bus body structure with analytical target cascading

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0718-y

摘要： Lightweight designs of new-energy vehicles can reduce energy consumption, thereby improving driving mileage. In this study, a lightweight design of a newly developed multi-material electric bus body structure is examined in combination with analytical target cascading (ATC). By proposing an ATC-based two-level optimization strategy, the original lightweight design problem is decomposed into the system level and three subsystem levels. The system-level optimization model is related to mass minimization with all the structural modal frequency constraints, while each subsystem-level optimization model is related to the sub-structural performance objective with sub-structure mass constraints. To enhance the interaction between two-level systems, each subsystem-level objective is reformulated as a penalty-based function coordinated with the system-level objective. To guarantee the accuracy of the model-based analysis, a finite element model is validated through experimental modal test. A sequential quadratic programming algorithm is used to address the defined optimization problem for effective convergence. Compared with the initial design, the total mass is reduced by 49 kg, and the torsional stiffness is increased by 17.5%. In addition, the obtained design is also validated through strength analysis.

关键词： electric vehicle     body in white (BIW)     lightweight     analytical target cascading (ATC)    

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标题 作者 时间 类型 操作

Application of semi-analytical finite element method to analyze the bearing capacity of asphalt pavements

Pengfei LIU, Dawei WANG, Frédéric OTTO, Markus OESER

期刊论文

Uncertainty propagation in dynamics of composite plates: A semi-analytical non-sampling-based approach

Mahdi FAKOOR, Hadi PARVIZ

期刊论文

Improvement of the assimilable organic carbon (AOC) analytical method for reclaimed water

Xin ZHAO, Hongying HU, Shuming LIU, Feng JIANG, Xiaolei SHI, Mingtang LI, Xueqiao XU

期刊论文

An analytical method for calculating torsional constants for arbitrary complicated thin-walled cross-sections

DU Baisong, GE Yaojun, ZHOU Zheng

期刊论文

Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

期刊论文

Comprehensive evaluation of heavy metal contamination of sediment in Lake Dianchi by using modified AHP method

ZHANG Yan, GAO Xiang, ZHONG Zhenyu, PENG Buzhuo, DENG Xihai

期刊论文

Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

期刊论文

环缝天线罩的近似分析方法

罗康, 孟进, 韩江枫, 朱丹妮

期刊论文

树盘干缩异向性引起应变的测算及分析

付宗营,赵景尧,蔡英春

期刊论文

Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

期刊论文

A method of analysis for modal aero-damping of vibrating blade in incompressible flow

Jun XING, Lin LI,

期刊论文

Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

期刊论文

stability of uncertain composite plates and stochastic irregularity in their buckling mode shapes: A semi-analytical

期刊论文

Analytical model and finite element computation of braking torque in electromagnetic retarder

Lezhi YE,Guangzhao YANG,Desheng LI

期刊论文

Lightweight design of an electric bus body structure with analytical target cascading

期刊论文