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Reliability and variance-based sensitivity analysis of arch dams during construction and reservoir impoundment

M. Houshmand KHANEGHAHI, M. ALEMBAGHERI, N. SOLTANI

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 526-541 doi: 10.1007/s11709-018-0495-1

摘要： The static performance of arch dams during construction and reservoir impoundment is assessed taking into account the effects of uncertainties presented in the model properties as well as the loading conditions. Dez arch dam is chosen as the case study; it is modeled along with its rock foundation using the finite element method considering the stage construction. Since previous studies concentrated on simplified models and approaches, comprehensive study of the arch dam model along with efficient and state-of-the-art uncertainty methods are incorporated in this investigation. The reliability method is performed to assess the safety level and the sensitivity analyses for identifying critical input factors and their interaction effects on the response of the dam. Global sensitivity analysis based on improved Latin hypercube sampling is employed in this study to indicate the influence of each random variable and their interaction on variance of the responses. Four levels of model advancement are considered for the dam-foundation system: 1) Monolithic dam without any joint founded on the homogeneous rock foundation, 2) monolithic dam founded on the inhomogeneous foundation including soft rock layers, 3) jointed dam including the peripheral and contraction joints founded on the homogeneous foundation, and 4) jointed dam founded on the inhomogeneous foundation. For each model, proper performance indices are defined through limit-state functions. In this manner, the effects of input parameters in each performance level of the dam are investigated. The outcome of this study is defining the importance of input factors in each stage and model based on the variance of the dam response. Moreover, the results of sampling are computed in order to assess the safety level of the dam in miscellaneous loading and modeling conditions.

关键词： concrete arch dams     reliability     randomness     improved Latin hypercube sampling     variance-based sensitivity analysis     exceedance probability     Sobol′ index    

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Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental bridge decks

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 480-501 doi: 10.1007/s11709-017-0435-5

摘要： In this paper, semi 3D models for segmental Bridge decks are created in ABAQUS CFD program with the support of MATLAB codes to simulate and analyze vortex shedding generated due to wind excitation through considering the stationary position of the deck. Three parameters (wind speed, deck streamlined length and dynamic viscosity of the air) are dedicated to study their effects on the kinetic energy of the system in addition to the shapes and patterns of the vortices. Two benchmarks from the literature Von Karman and Dyrbye and Hansen are considered to validate the vortex shedding aspects for the CFD models. Good agreement between the results of the benchmarks and the semi 3D models has been detected. Latin hypercube experimental method is dedicated to generate the surrogate models for the kinetic energy of the system and the lift forces. Variance based sensitivity analysis is utilized to calculate the main sensitivity indices and the interaction orders for all the three parameters. The kinetic energy approach performed very well in revealing the rational effects and the roles of each parameter in the generation of vortex shedding and predicting vortex induced vibration of the deck.

关键词： vortex induced vibration     reynolds number     kinetic energy     vorticity     latin hypercube sampling    

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A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

《工程管理前沿（英文）》 2017年 第4卷 第3期   页码 338-347 doi: 10.15302/J-FEM-2017032

摘要： This study aims to solve a typical long-term strategic decision problem on supply chain network design with consideration to uncertain demands. Existing methods for these problems are either deterministic or limited in scale. We analyze the impact of uncertainty on demand based on actual large data from industrial companies. Deterministic equivalent model with nonanticipativity constraints, branch-and-fix coordination, sample average approximation (SAA) with Bayesian bootstrap, and Latin hypercube sampling were adopted to analyze stochastic demands. A computational study of supply chain network with front-ends in Europe and back-ends in Asia is presented to highlight the importance of stochastic factors in these problems and the efficiency of our proposed solution approach.

关键词： supply chain network     stochastic demand     sampling average approximation     Bayesian bootstrap     Latin hypercube sampling    

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Introduction to the special issue on the VIII Latin-American Congress on Mechanical Engineering

Marco CECCARELLI,René-Vinicio SÁNCHEZ

《机械工程前沿（英文）》 2015年 第10卷 第3期   页码 219-220 doi: 10.1007/s11465-015-0356-8

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线性人脸对象类模型的匹配提升技术

付昀,郑南宁

《中国工程科学》 2005年 第7卷 第2期   页码 47-56

摘要：

针对真实感人脸模型匹配的细节控制和稳健创建问题，提出了线性人脸对象类模型的匹配提升技术。基于非统一抽样(NUS)的动态高斯金字塔分析(DGPA)方法，结合不等概率抽样和整群抽样策略，自适应地动态调整每级高斯金字塔图像的抽样分布，利用最优化算法由粗到精的计算全局近似最优解，获得精确的模型匹配。动态调节整群区域边界并利用再抽样率调节抽样密度，可以有效控制人像模型的细节表达效果，提高模型创建的稳健性。随机梯度下降的线性相关性扰动(CD-SGD)和学习率自适应(ALR)技术，提高了模型匹配的准确性和收敛速度。以MPI和AI&R人像库为测试样本，主观与客观评价的实验结果验证了该模型匹配提升技术的有效性。

关键词： 人脸建模     模型匹配     随机梯度下降     非统一抽样     多分辨率分析    

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Numerical simulation and experimental research on the wheel brush sampling process of an asteroid sampler

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0732-0

摘要： To examine the environmental characteristics of the microgravity force and the weathered layer on an asteroid surface, a symmetric wheel brush asteroid sampler is proposed for the collection of particles on the asteroid surface. To study the influence of the wheel brush rotation speed on the sampling efficiency and the driving torque required for the wheel brush, the contact dynamics model between particles and sampling wheel brushes is established and a simulation and experimental verification of the sampling process are conducted. The parameter calibration of the sampled particles is studied first, and the calibrated particle parameters are used in the numerical simulation of the sampling process. The sampling results and the particle stream curves are obtained for the working conditions of different rotation speeds, and the effects of different parameter settings on the sampling efficiency are analyzed. In addition, a set of rotating symmetrical sampling wheel brush devices is built for the ground test, and the dynamic torque sensor is used to test the torque change of the wheel brush during the sampling process. The relationship between the speed of the wheel brush and the driving torque of the wheel brush motor is determined by comparing the simulation results with the test results. Results indicate that when the rotating speed of the wheel brush is faster, the sampling efficiency is higher, and the driving torque required for the sampling wheel brush is greater. Moreover, a numerical simulation analysis of the sampling process of the wheel brush sampler in a microgravity environment is conducted to determine the optimal speed condition, and the brushing test of the wheel brush sampler in the microgravity environment is verified with the drop tower method. This research proposes the structural optimization design and motor selection of a wheel brush asteroid sampler, which provides important reference value and engineering significance.

关键词： asteroid sampling     wheel brush sampler     discrete element method     parameter calibration     experimental research    

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Investigation on sampling artifacts of particle associated PAHs using ozone denuder systems

Kai LIU, Fengkui DUAN, Kebin HE, Yongliang MA, Yuan CHENG

《环境科学与工程前沿（英文）》 2014年 第8卷 第2期   页码 284-292 doi: 10.1007/s11783-013-0555-7

摘要： Polycyclic aromatic hydrocarbons (PAHs) are complex organic compounds which are identified as significant carcinogenic to human health. PAHs (mainly in particle phase) are susceptible to atmospheric oxidant gases, especially ozone, nitrogen oxides (NO ), hydroxyl radical (OH), and could be degraded on filters during sampling process, leading to an underestimation of ambient PAH concentrations. The goal of this work was to investigate particle associated PAHs sampling artifacts caused by ozone in summer of Beijing. Comparative sampling systems were operated simultaneously during the whole campaign, one with activated carbon ozone denuder, the other being set as conventional sampling system. Activated carbon denuder was testified to be highly efficient to eliminate ozone from air stream. In general, nine particle-bound PAHs observed from conventional sampler were all lower than those from ozone denuder system. The total PAHs (particle phase) concentration was averagely underestimated by 35.9% in conventional sampling procedure. Benzo[a]pyrene (BaP) had the highest percentage of mass loss. Ambient temperature was founded to have influences on PAHs sampling artifacts. High temperature can increase loss of particle associated PAHs during sampling.

关键词： particle associated polycyclic aromatic hydrocarbons (PAHs)     ozone     denuder     sampling artifacts    

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A sampling method based on URL clustering for fast web accessibility evaluation

Meng-ni ZHANG,Can WANG,Jia-jun BU,Zhi YU,Yu ZHOU,Chun CHEN

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 449-456 doi: 10.1631/FITEE.1400377

摘要： When evaluating the accessibility of a large website, we rely on sampling methods to reduce the cost of evaluation. This may lead to a biased evaluation when the distribution of checkpoint violations in a website is skewed and the selected samples do not provide a good representation of the entire website. To improve sampling quality, stratified sampling methods first cluster web pages in a site and then draw samples from each cluster. In existing stratified sampling methods, however, all the pages in a website need to be analyzed for clustering, causing huge I/O and computation costs. To address this issue, we propose a novel page sampling method based on URL clustering for web accessibility evaluation, namely URLSamp. Using only the URL information for stratified page sampling, URLSamp can efficiently scale to large websites. Meanwhile, by exploiting similarities in URL patterns, URLSamp cluster pages by their generating scripts and can thus effectively detect accessibility problems from web page templates. We use a data set of 45 web sites to validate our method. Experimental results show that our URLSamp method is both effective and efficient for web accessibility evaluation.

关键词： Page sampling     URL clustering     Web accessibility evaluation    

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Dilution sampling and analysis of particulate matter in biomass-derived syngas

Xiaoliang WANG, Curtis ROBBINS, S. Kent HOEKMAN, Judith C. CHOW, John G. WATSON, Dennis SCHUETZLE

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 320-330 doi: 10.1007/s11783-011-0347-x

摘要： Thermochemical biomass gasification, followed by conversion of the produced syngas to fuels and electrical power, is a promising energy alternative. Real-world characterization of particulate matter (PM) and other contaminants in the syngas is important to minimize damage and ensure efficient operation of the engines it powers and the fuels created from it. A dilution sampling system is demonstrated to quantify PM in syngas generated from two gasification plants utilizing different biomass feedstocks: a BioMax 15 Biopower System that uses raw and torrefied woodchips as feedstocks, and an integrated biorefinery (IBR) that uses rice hulls and woodchips as feedstocks. PM mass concentrations in syngas from the IBR downstream of the purification system were 12.8–13.7 μg·m , which were significantly lower than the maximum level for catalyst protection (500 μg·m ) and were 2–3 orders of magnitude lower than those in BioMax 15 syngas (2247–4835 μg·m ). Ultrafine particle number concentration and PM chemical constituents were also much lower in the IBR syngas than in the BioMax 15. The dilution sampling system enabled reliable measurements over a wide range of concentrations: the use of high sensitivity instruments allowed measurement at very low concentrations (~1 μg·m ), while the flexibility of dilution minimized sampling problems that are commonly encountered due to high levels of tars in raw syngas (~1 g·m ).

关键词： dilution source sampling     syngas characterization     biomass gasification     ultrafine particles    

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Unified methodology for site-characterization and sampling of highway runoff

Jy S. WU, Craig J. ALLAN,

《环境科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 47-58 doi: 10.1007/s11783-010-0003-x

摘要： Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables. Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring programs that are subject to sampling and resources constraints.

关键词： highway runoff     pollutant loads     regression models     non-point source pollution     storm water permit    

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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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亚奈奎斯特采样的数据恢复：性能极限与恢复算法

罗茜倩,张朝阳

《信息与电子工程前沿（英文）》 2021年 第22卷 第2期   页码 141-286 doi: 10.1631/FITEE.1900320

摘要： 奈奎斯特频率是一般带限信号进行无损采样的采样率下界，然而在某些情景中，亚奈奎斯特频率也足以进行无损采样和信号恢复。以往对亚奈奎斯特采样的研究主要集中在利用信号变换来降低信号维度，但是亚奈奎斯特采样信号的结构并没有得到充分研究。本文针对线性调制基带信号的亚奈奎斯特采样，研究其信号恢复性能极限与算法。该问题中，原信号维度无法降低，因此亚奈奎斯特采样不可避免会带来信息损失，信号恢复也变成一个欠定线性问题。本文采用两种亚奈奎斯特采样方法对线性调制基带信号进行采样，分别研究了两种采样方法下的性能极限和信号恢复算法。首先，针对两种亚奈奎斯特采样方法，分别计算了采样序列之间的最小归一化欧氏距离，以此作为最优性能的指标。然后，在基带信号有限符号集的限制条件下，采用改进的时变维特比算法从亚奈奎斯特采样序列中恢复原信号。将仿真得到的亚奈奎斯特采样的误比特率与其性能的理论极限比较，并与奈奎斯特采样性能对比，验证了时变维特比算法在信号恢复问题中的优良性能。

关键词： 奈奎斯特采样定理；亚奈奎斯特采样；最小欧式距离；欠定线性问题；时变维特比算法    

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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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LARGE-SCALE FARMING BENEFITS SOIL ACIDIFICATION ALLEVIATION THROUGH IMPROVED FIELD MANAGEMENT IN BANANA

《农业科学与工程前沿（英文）》 2023年 第10卷 第1期   页码 48-60 doi: 10.15302/J-FASE-2022475

摘要：

● Large farms had the highest average yield and the least yield variation.

关键词： plantations     land transfer     large-scale farming     nutrient management     soil acidification    

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Cluster voltage control method for “Whole County” distributed photovoltaics based on improved differential

《能源前沿（英文）》   页码 782-795 doi: 10.1007/s11708-023-0905-8

摘要： China is vigorously promoting the “whole county promotion” of distributed photovoltaics (DPVs). However, the high penetration rate of DPVs has brought problems such as voltage violation and power quality degradation to the distribution network, seriously affecting the safety and reliability of the power system. The traditional centralized control method of the distribution network has the problem of low efficiency, which is not practical enough in engineering practice. To address the problems, this paper proposes a cluster voltage control method for distributed photovoltaic grid-connected distribution network. First, it partitions the distribution network into clusters, and different clusters exchange terminal voltage information through a “virtual slack bus.” Then, in each cluster, based on the control strategy of “reactive power compensation first, active power curtailment later,” it employs an improved differential evolution (IDE) algorithm based on Cauchy disturbance to control the voltage. Simulation results in two different distribution systems show that the proposed method not only greatly improves the operational efficiency of the algorithm but also effectively controls the voltage of the distribution network, and maximizes the consumption capacity of DPVs based on qualified voltage.

关键词： distributed photovoltaics (DPVs)     cluster partitioning     improved differential evolution algorithm     voltage control     consumption capacity of distributed photovoltaics    

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标题 作者 时间 类型 操作

Reliability and variance-based sensitivity analysis of arch dams during construction and reservoir impoundment

M. Houshmand KHANEGHAHI, M. ALEMBAGHERI, N. SOLTANI

期刊论文

Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental bridge decks

Nazim Abdul NARIMAN

期刊论文

A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

期刊论文

Introduction to the special issue on the VIII Latin-American Congress on Mechanical Engineering

Marco CECCARELLI,René-Vinicio SÁNCHEZ

期刊论文

线性人脸对象类模型的匹配提升技术

付昀,郑南宁

期刊论文

Numerical simulation and experimental research on the wheel brush sampling process of an asteroid sampler

期刊论文

Investigation on sampling artifacts of particle associated PAHs using ozone denuder systems

Kai LIU, Fengkui DUAN, Kebin HE, Yongliang MA, Yuan CHENG

期刊论文

A sampling method based on URL clustering for fast web accessibility evaluation

Meng-ni ZHANG,Can WANG,Jia-jun BU,Zhi YU,Yu ZHOU,Chun CHEN

期刊论文

Dilution sampling and analysis of particulate matter in biomass-derived syngas

Xiaoliang WANG, Curtis ROBBINS, S. Kent HOEKMAN, Judith C. CHOW, John G. WATSON, Dennis SCHUETZLE

期刊论文

Unified methodology for site-characterization and sampling of highway runoff

Jy S. WU, Craig J. ALLAN,

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

亚奈奎斯特采样的数据恢复：性能极限与恢复算法

罗茜倩,张朝阳

期刊论文

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

期刊论文

LARGE-SCALE FARMING BENEFITS SOIL ACIDIFICATION ALLEVIATION THROUGH IMPROVED FIELD MANAGEMENT IN BANANA

期刊论文

Cluster voltage control method for “Whole County” distributed photovoltaics based on improved differential

期刊论文