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Critical flow-storm approach to total maximum daily load (TMDL) development: an analytical conceptual

Zhang Harry, Yu Shaw

《环境科学与工程前沿（英文）》 2008年 第2卷 第3期   页码 267-273 doi: 10.1007/s11783-008-0058-0

摘要： One of the key challenges in the total maximum daily load (TMDL) development process is how to define the critical condition for a receiving waterbody. The main concern in using a continuous simulation approach is the absence of any guarantee that the most critical condition will be captured during the selected representative hydrologic period, given the scarcity of long-term continuous data. The objectives of this paper are to clearly address the critical condition in the TMDL development process and to compare continuous and event-based approaches in defining critical condition during TMDL development for a waterbody impacted by both point and nonpoint source pollution. A practical, event-based critical flow-storm (CFS) approach was developed to explicitly addresses the critical condition as a combination of a low stream flow and a storm event of a selected magnitude, both having certain frequencies of occurrence. This paper illustrated the CFS concept and provided its theoretical basis using a derived analytical conceptual model. The CFS approach clearly defined a critical condition, obtained reasonable results and could be considered as an alternative method in TMDL development.

关键词： representative hydrologic     occurrence     simulation approach     scarcity     alternative    

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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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Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

Jiping GE, M. Saiid SAIIDI, Sebastian VARELA

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 149-164 doi: 10.1007/s11709-018-0482-6

摘要： This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic performance. The bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled shafts. It will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA) and engineered cementitious composite (ECC) to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software OpenSees. Two versions of the same bridge were analyzed and compared, one with conventional cast-in-place reinforced concrete columns, and the other with top plastic hinges incorporating Nickel-Titanium (NiTi) SMA reinforcing bars and ECC. The novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure, but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic hinges. The analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design     analytical simulation     near-fault earthquakes     shape memory alloy     engineered cementitious composite     self-centering    

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Improved analytical model for residual stress prediction in orthogonal cutting

null

《机械工程前沿（英文）》 2014年 第9卷 第3期   页码 249-256 doi: 10.1007/s11465-014-0310-1

摘要：

The analytical model of residual stress in orthogonal cutting proposed by Jiann is an important tool for residual stress prediction in orthogonal cutting. In application of the model, a problem of low precision of the surface residual stress prediction is found. By theoretical analysis, several shortages of Jiann’s model are picked out, including: inappropriate boundary conditions, unreasonable calculation method of thermal stress, ignorance of stress constraint and cyclic loading algorithm. These shortages may directly lead to the low precision of the surface residual stress prediction. To eliminate these shortages and make the prediction more accurate, an improved model is proposed. In this model, a new contact boundary condition between tool and workpiece is used to make it in accord with the real cutting process; an improved calculation method of thermal stress is adopted; a stress constraint is added according to the volume-constancy of plastic deformation; and the accumulative effect of the stresses during cyclic loading is considered. At last, an experiment for measuring residual stress in cutting AISI 1045 steel is conducted. Also, Jiann’s model and the improved model are simulated under the same conditions with cutting experiment. The comparisons show that the surface residual stresses predicted by the improved model is closer to the experimental results than the results predicted by Jiann’s model.

关键词： residual stress     analytical model     orthogonal cutting     cutting force     cutting temperature    

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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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δN-stable isotope analysis of NH: An overview on analytical measurements, source sampling and its source

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1414-6

摘要：

• Challenges in sampling of NH3 sources for d15N analysis are highlighted.

关键词： Aerosol ammonium     Atmospheric gaseous ammonia     Isotope fingerprinting     Isotope-based source apportionment     Ammonia gas-to-particle conversion    

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Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 435-450 doi: 10.1007/s11465-021-0630-x

摘要： Seven-degree-of-freedom redundant manipulators with link offset have many advantages, including obvious geometric significance and suitability for configu-ration control. Their configuration is similar to that of the experimental module manipulator (EMM) in the Chinese Space Station Remote Manipulator System. However, finding the analytical solution of an EMM on the basis of arm angle parameterization is difficult. This study proposes a high-precision, semi-analytical inverse method for EMMs. Firstly, the analytical inverse kinematic solution is established based on joint angle parameterization. Secondly, the analytical inverse kinematic solution for a non-offset spherical–roll–spherical (SRS) redundant manipulator is derived based on arm angle parameterization. The approximate solution of the EMM is calculated in accordance with the relationship between the joint angles of the EMM and the SRS manipulator. Thirdly, the error is corrected using a numerical method through the analytical inverse solution based on joint angle parameterization. After selecting the stride and termination condition, the precise inverse solution is computed for the EMM based on arm angle parameterization. Lastly, case solutions confirm that this method has high precision, and the arm angle parameterization method is superior to the joint angle parameterization method in terms of parameter selection.

关键词： 7-DOF redundant manipulator     inverse kinematics     semi-analytical     arm angle     link offset    

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Comparison of analytical procedures for measuring phosphorus content of animal manures in China

null

《农业科学与工程前沿（英文）》 2019年 第6卷 第4期   页码 431-440 doi: 10.15302/J-FASE-2019279

摘要：

The concentration and components of manure phosphorus (P) are key factors determining potential P bioavailability and runoff. The distribution of P forms in swine, poultry and cattle manures collected from intensive and extensive production systems in several areas of China was investigated with sequential fractionation and a simplified two-step (NaHCO -NaOH/EDTA) procedures. The mean total P concentration, determined by the sequential fractionation procedure of intensive swine, poultry and cattle manure, expressed as g·kg , was 14.9, 13.4 and 5.8 g·kg , respectively, and 4.4 g·kg in extensive cattle manure. In intensive swine, poultry and cattle manure about 73%, 74% and 79% of total P, respectively, was bioavailable (i.e., P extracted by H O and NaHCO ) and 78% in extensive cattle manure. The results indicated the relative environmental risk, from high to low, of swine, poultry and cattle manure. There is considerable regional variation in animal manure P across China, which needs to be considered when developing manure management strategies.

关键词： diet phosphorus     manure phosphorus     sequential P fractionation    

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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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Vanadium and molybdenum concentrations in particulate from Palermo (Italy): analytical methods using

Diana AMORELLO,Santino ORECCHIO

《环境科学与工程前沿（英文）》 2015年 第9卷 第4期   页码 605-614 doi: 10.1007/s11783-014-0703-8

摘要： The main purpose of this work was to develop a reliable method for the determination of vanadium (V) and molybdenum (Mo) in atmosphere particles or aerosols because they can not be readily measured using conventional techniques. For this research, 30 particulate samples were collected from five different stations located at Palermo, Italy. We used the catalytic adsorptive stripping voltammetry and differential pulsed voltammetry to measure V and Mo in atmospheric particulate, respectively. The represented method includes advantages of high sensitivity, high selectivity, simplicity, reproducibility, speed and low costs. The quantification limits for V and Mo are, respectively, 0.57 and 0.80 ng·m . The precision, expressed as relative standard deviation (RSD %), was about 2% for both metals. The mean recoveries of added V and Mo were about 99.5% and ranged from 97% to 101%. Vanadium concentrations in particulate samples collected in Palermo area ranged from 0.57 to 7.7 ng·m , while Mo concentrations were in the range 0.8–51 ng·m . In many cases the concentrations of two elements in the particulate samples fall below the detection limits. The mean concentrations for V and Mo in particulate samples, collected in Palermo area, were respectively 3.1 and 5.9 ng·m .

关键词： vanadium     molybdenum     particulate     voltammetry     Palermo    

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Simplified analytical solution for free vibration characteristics of Hardfill dam

XIAO Wei, HE Yunlong, ZHANG Yanfeng

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 219-225 doi: 10.1007/s11709-008-0037-3

摘要： Formulas for computing natural frequencies and modes of Hardfill dams are derived based on one-dimensional shear wedge theory, in which the influences of the upstream concrete face and hydrodynamic pressure of water on the dams’ natural frequencies and modes are discussed. Furthermore, the seismic responses of Hardfill dams are calculated using response spectrum method. An example is analyzed to compare the differences of natural frequencies and modes between shear wedge method and FEM. Then the applicability and accuracy of shear wedge method to analyze free vibration characteristics of Hardfill dams are proven.

关键词： upstream concrete     hydrodynamic pressure     vibration     one-dimensional     applicability    

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Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-021-0671-1

摘要： The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.

关键词： axial piston pump     rotating parts     high rotational speed     churning losses     drag torque    

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Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 1-12 doi: 10.1007/s11465-007-0001-2

摘要： Thin films and multi-layered coatings comprised of different classes of materials are often used for various functional devices. The thermo-mechanical integrity of these systems is becoming a major concern and is strongly related to the residual stresses because of the fabrication processes. In this paper, the sources of the residual stresses in the coating-based systems and the concept of misfit strain were briefly reviewed. Analytical models were developed to predict the residual stresses in multi-layered film structures or coating-based systems using the force and moment balances. In addition, the residual stress distributions in the func tionally and compositionally graded coatings were also analyzed.

关键词： briefly     different     thermo-mechanical integrity     addition     residual    

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Impact analytical models for earthquake-induced pounding simulation

Kun YE, Li LI

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 142-147 doi: 10.1007/s11709-009-0029-y

摘要： Structural pounding under earthquake has been recently extensively investigated using various impact analytical models. In this paper, a brief review on the commonly used impact analytical models is conducted. Based on this review, the formula used to determine the damping constant related to the impact spring stiffness, coefficient of restitution, and relative approaching velocity in the Hertz model with nonlinear damping is found to be incorrect. To correct this error, a more accurate approximating formula for the damping constant is theoretically derived and numerically verified. At the same time, a modified Kelvin impact model, which can reasonably account for the physical nature of pounding and conveniently implemented in the earthquake-induced pounding simulation of structural engineering is proposed.

关键词： structural pounding     Hertz model     Kelvin model     nonlinear damping     coefficient of restitution    

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An improved algorithm for McDowell’s analytical model of residual stress

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 150-155 doi: 10.1007/s11465-014-0295-9

摘要：

The analytical model for two-dimensional elastoplastic rolling/sliding contact proposed by McDowell is an important tool for predicting residual stress in rolling/sliding processes. In application of the model, a problem of low predicting precision near the surface layer of the component is found. According to the volume-constancy of plastic deformation, an improved algorithm for McDowell’s model is proposed in order to improve its predicting accuracy of the surface residual stress. In the algorithm, a relationship between three normal stresses perpendicular to each other at any point within the component is derived, and the relationship is applied to McDowell’s model. Meanwhile, an unnecessary hypothesis proposed by McDowell can be eliminated to make the model more reasonable. The simulation results show that the surface residual stress predicted by modified method is much closer to the FEM results than the results predicted by McDowell’s model under the same simulation conditions.

关键词： residual stress     McDowell’s model     volume-constancy of plastic deformation     FEM     elastoplastic rolling/sliding contact    

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标题 作者 时间 类型 操作

Critical flow-storm approach to total maximum daily load (TMDL) development: an analytical conceptual

Zhang Harry, Yu Shaw

期刊论文

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

期刊论文

Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

Jiping GE, M. Saiid SAIIDI, Sebastian VARELA

期刊论文

Improved analytical model for residual stress prediction in orthogonal cutting

null

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

δN-stable isotope analysis of NH: An overview on analytical measurements, source sampling and its source

期刊论文

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

期刊论文

Comparison of analytical procedures for measuring phosphorus content of animal manures in China

null

期刊论文

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

Vanadium and molybdenum concentrations in particulate from Palermo (Italy): analytical methods using

Diana AMORELLO,Santino ORECCHIO

期刊论文

Simplified analytical solution for free vibration characteristics of Hardfill dam

XIAO Wei, HE Yunlong, ZHANG Yanfeng

期刊论文

Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

期刊论文

Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

期刊论文

Impact analytical models for earthquake-induced pounding simulation

Kun YE, Li LI

期刊论文

An improved algorithm for McDowell’s analytical model of residual stress

null

期刊论文