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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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composite plates and stochastic irregularity in their buckling mode shapes: A semi-analytical non-intrusive approach

《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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混沌工程学

龙运佳

《中国工程科学》 2001年第3卷第2期页码 10-15

摘要：

世界是非线性的，线性只是其近似描述，混沌的发现表明：某些确定性非线性系统具有内在的随机行为。事实上，以往20年，无所不在的混沌现象几乎在每个学科都有所报道，如数学、物理学、化学，甚至社会科学。但理论研究学者的主要兴趣在于探究混沌的本质。与此同时，混沌的实际利用在许多工程领域受到重视，如信息工程、系统工程、医药工程、农业工程、电气工程、生物工程、机械工程、土木工程等。混沌工程学是一门新的研究混沌实际利用及其基本理论的非线性工程科学。文章对现代混沌工程学的定义、对象、概念、方法、理论与应用加以总结，并介绍其近来的进展及作者的工作。混沌工程学在国民经济与国防建设中研究的热点是：混沌分析技术，混沌控制技术与混沌生成技术。

关键词：非线性混沌振荡振动波

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Short-term prediction of the influent quantity time series of wastewater treatment plant based on a chaos

LI Xiaodong, ZENG Guangming, HUANG Guohe, LI Jianbing, JIANG Ru

《环境科学与工程前沿（英文）》 2007年第1卷第3期页码 334-338 doi: 10.1007/s11783-007-0057-6

摘要： By predicting influent quantity, a wastewater treatment plant (WWTP) can be well controlled. The nonlinear dynamic characteristic of WWTP influent quantity time series was analyzed, with the assumption that the series was predictable. Based on this, a short-term forecasting chaos neural network model of WWTP influent quantity was built by phase space reconstruction. Reasonable forecasting results were achieved using this method.

关键词： nonlinear reconstruction WWTP influent characteristic Reasonable forecasting

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指数多项式均匀样条模型

赵颜利,平萍,刘凤玉

《中国工程科学》 2008年第10卷第7期页码 147-152

摘要：

给出了k（ k ≥ ３）阶指数多项式的均匀样条模型。该类模型具有很多与B 样条模型相同的性质，并且增加了一个可调节的形状参数。由该模型构造的曲线，通过改变形状参数的取值，可以调整曲线接近其控制多边形的程度。应用于CAD/CAM领域，可作为几何造型的一种新的有效模型。

关键词：指数多项式样条函数 B样条函数形状参数

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高阶高斯积分节点的高精度数值计算

张庆礼,王晓梅,殷绍唐,江海河

《中国工程科学》 2008年第10卷第2期页码 35-40

摘要：

在工程数值计算、X射线衍射线形分析、光谱学等领域常使用高斯数值积分，高斯积分的节点及权重因子是数值积分的必须数据。研究了高次勒让德、拉盖尔和厄米多项式的零点，即高斯-勒让德、高斯-拉盖尔、高斯-厄米积分的节点的计算方法，给出了一种有效的高精度数值算法——搜索迭代方法（scan-iteration method，SIM）。根据勒让德、拉盖尔、厄米多项式的特点，对拉盖尔多项式、厄米多项式的定义稍做变化后，获得了计算多项式值的稳定递推关系。求它们的根时，先在一定范围内以一定的步长搜索根所在的

关键词：高斯积分勒让德多项式拉盖尔多项式厄米多项式求根

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Application of a Novel Fuzzy Clustering Method Based on Chaos Immune Evolutionary Algorithm for Edge

《机械工程前沿（英文）》 2006年第1卷第1期页码 85-89 doi: 10.1007/s11465-005-0023-6

摘要：

A novel fuzzy clustering method based on chaos immune evolutionary algorithm (CIEFCM) is presented to solve fuzzy edge detection problems in image processing. In CIEFCM, a tiny disturbance is added to a filial generation group using a chaos variable and the disturbance amplitude is adjusted step by step, which greatly improves the colony diversity of the immune evolution algorithm (IEA). The experimental results show that the method not only can correctly detect the fuzzy edge and exiguous edge but can evidently improve the searching efficiency of fuzzy clustering algorithm based on IEA.

关键词： disturbance amplitude disturbance diversity generation processing

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一个基于混沌的分组密码算法的分析

金晨辉

《中国工程科学》 2001年第3卷第6期页码 75-80

摘要：

“基于混沌的分组密码置换网络的设计”一文提出的一个分组密码算法在已知明文攻击和唯密文攻击下都是很容易被破译的,而且在知道加密变换的条件下,很容易利用分割攻击方法求出该分组密码的密钥。此外,基于Logistic映射的混沌序列的相邻值之间的相互制约性,以及该混沌序列的前若干值对初值的低位比特不敏感。

关键词：混沌序列分组密码移位密码唯密文攻击已知明文攻击分割攻击

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Enhancement of the polynomial functions response surface model for real-time analyzing ozone sensitivity

Jiangbo Jin, Yun Zhu, Jicheng Jang, Shuxiao Wang, Jia Xing, Pen-Chi Chiang, Shaojia Fan, Shicheng Long

《环境科学与工程前沿（英文）》 2021年第15卷第2期 doi: 10.1007/s11783-020-1323-0

摘要： Abstract • The calculation process and algorithm of response surface model (RSM) were enhanced. • The prediction errors of RSM in the margin and transition areas were greatly reduced. • The enhanced RSM was able to analyze O3-NOx-VOC sensitivity in real-time. • The O3 formations were mainly sensitive to VOC, for the two case study regions. Quantification of the nonlinearities between ambient ozone (O3) and the emissions of nitrogen oxides (NOx) and volatile organic compound (VOC) is a prerequisite for an effective O3 control strategy. An Enhanced polynomial functions Response Surface Model (Epf-RSM) with the capability to analyze O3-NOx-VOC sensitivities in real time was developed by integrating the hill-climbing adaptive method into the optimized Extended Response Surface Model (ERSM) system. The Epf-RSM could single out the best suited polynomial function for each grid cell to quantify the responses of O3 concentrations to precursor emission changes. Several comparisons between Epf-RSM and pf-ERSM (polynomial functions based ERSM) were performed using out-of-sample validation, together with comparisons of the spatial distribution and the Empirical Kinetic Modeling Approach diagrams. The comparison results showed that Epf-RSM effectively addressed the drawbacks of pf-ERSM with respect to over-fitting in the margin areas and high biases in the transition areas. The O3 concentrations predicted by Epf-RSM agreed well with Community Multi-scale Air Quality simulation results. The case study results in the Pearl River Delta and the north-western area of the Shandong province indicated that the O3 formations in the central areas of both the regions were more sensitive to anthropogenic VOC in January, April, and October, while more NOx-sensitive in July.

关键词： Response surface model Hill-climbing algorithm Ozone pollution Precursor emissions Control strategy

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基于混沌的分组密码置换网络的设计

孙枫,秦红磊,徐耀群,郝燕玲

《中国工程科学》 2000年第2卷第9期页码 47-49

摘要：

文章利用混沌序列的遍历性，给出了一种分组密码置换网络的设计，并对混沌序列的遍历性和置换网络的时间复杂度做了分析。计算机模拟结果显示，混沌分组密码置换网络具有复杂性高、抗破译性强的优点，可以增强信息系统的安全性。

关键词：混沌序列置换网络遍历性时间复杂度

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A new type of quadratic acceleration method

Changqing LI, Menglin LOU,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 302-310 doi: 10.1007/s11709-010-0026-1

摘要： The polynomial acceleration method for time history analysis is presented, in which accelerations between several equal neighboring time steps were assumed to be a polynomial function of time interval. With a higher order polynomial used, a higher accuracy can be obtained, but the stability field of the method becomes narrower. When stability field and computational accuracy are taken into account at the same time, the quadratic acceleration method is superior to linear and cubic acceleration methods in choosing the maximum acceptable time step size. It is also shown that the quadratic acceleration method has desirable arithmetic damp, amplitude decay rate and period elongation rate, though its conditional stability restricts its application in stiff structures.

关键词： polynomial acceleration method convergence stability square acceleration method

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Whole-life Thinking and Engineering the Future

Roger Flanagan

《工程管理前沿（英文）》 2014年第1卷第3期页码 290-296 doi: 10.15302/J-FEM-2014040

摘要： Whole-life thinking for engineers working on the built environment has become more important in a fast changing world. Whole-life thinking is not new, every project attempts to balance the initial capital cost with the operating and maintenance cost of an asset. Engineers are increasingly concerned with complex systems, in which the parts interact with each other and with the outside world in many ways — the relationships between the parts determine how the system behaves. Systems thinking provides one approach to developing a more robust whole-life approach. Systems thinking is a process of understanding how things influence one another within a wider perspective. Complexity, chaos, and risk are endemic in all major projects. New approaches are needed to produce more reliable whole-life predictions. Best value, rather than lowest cost, can be achieved by using whole-life appraisal as a part of the design and delivery strategy.

关键词： whole-life thinking systems thinking complexity chaos risk management through life

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基于对称多项式辅助的中国余数定理的脉冲多普勒雷达多目标距离估计算法 Research Articles

曹成虎1,赵永波1,2

《信息与电子工程前沿（英文）》 2022年第23卷第2期页码 304-316 doi: 10.1631/FITEE.2000418

摘要：工作在高脉冲重复频率的脉冲多普勒雷达能避免多普勒模糊，但是高脉冲重复频率在许多场合导致距离模糊。目前，解决距离模糊的有效方案是基于波形设计，但是增加了雷达系统的复杂性。由于目标距离和量测距离的对应关系未知，传统的基于多脉冲重复频率方案，特别是中国余数定理，很难应用于多目标距离解模糊。本文旨在研究量测距离含有误差的基于中国余数定理多目标距离估计方法。提出基于对称多项式辅助的中国余数定理，能有效从含有误差的量测距离中重建多目标距离。封闭式鲁棒中国余数定理和基于Aitken加速算法的多项式方程求解方法能有效降低所提算法的计算复杂度。

关键词：距离模糊；误差距离；多目标；对称多项式辅助的中国余数定理

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Multiobjective trajectory optimization of intelligent electro-hydraulic shovel

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0706-2

摘要： Multiobjective trajectory planning is still face challenges due to certain practical requirements and multiple contradicting objectives optimized simultaneously. In this paper, a multiobjective trajectory optimization approach that sets energy consumption, execution time, and excavation volume as the objective functions is presented for the electro-hydraulic shovel (EHS). The proposed cubic polynomial S-curve is employed to plan the crowd and hoist speed of EHS. Then, a novel hybrid constrained multiobjective evolutionary algorithm based on decomposition is proposed to deal with this constrained multiobjective optimization problem. The normalization of objectives is introduced to minimize the unfavorable effect of orders of magnitude. A novel hybrid constraint handling approach based on -constraint and the adaptive penalty function method is utilized to discover infeasible solution information and improve population diversity. Finally, the entropy weight technique for order preference by similarity to an ideal solution method is used to select the most satisfied solution from the Pareto optimal set. The performance of the proposed strategy is validated and analyzed by a series of simulation and experimental studies. Results show that the proposed approach can provide the high-quality Pareto optimal solutions and outperforms other trajectory optimization schemes investigated in this article.

关键词： trajectory planning electro-hydraulic shovel cubic polynomial S-curve multiobjective optimization entropy weight technique

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Nonlinear dynamics and analysis of a four-bar linkage with clearance

Yuanguang TANG, Zongyu CHANG, Xiaogang DONG, Yafei HU, Zhenjiang YU

《机械工程前沿（英文）》 2013年第8卷第2期页码 160-168 doi: 10.1007/s11465-013-0258-6

摘要：

In this paper, nonlinear dynamic behavior of a four-bar linkage considering clearance is studied. The dynamic model of the linkage with a clearance between coupler and rocker is developed firstly. Then the dynamic equations of this mechanism are solved by a numerical method. According to the calculated response, compliance, force and trajectory of pin in joint bearing are obtained. Effects of clearance magnitude and the relationship between a mechanism with clearance and without clearance are studied. By using Poincare Map, it is proved that strange attractors or chaos exist in the dynamic response. In addition, phenomena of chaos, periodic response and subharmonic response also can be found in the special condition. Bifurcation diagram is used to suggest that bifurcation and fractal phenomena exist in the dynamic response of this mechanism.

关键词： four-bar linkage chaos bifurcation strange attractors dynamics