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81.
A novel computational approach for the dynamic analysis of a large scale rigid–flexible multibody system composed of composite
laminated plates is proposed. The rigid parts in the system are described through the Natural Coordinate Formulation (NCF)
and the flexible bodies in the system are modeled via the finite elements of Absolute Nodal Coordinate Formulation (ANCF),
which can lead to a constant mass matrix for the derived system equation of motion. For modeling composite laminated plates
accurately, a new composite laminated plate element of ANCF is proposed and the corresponding efficient formulations for evaluating
both the elastic force and its Jacobian of the element are derived from the first Piola–Kirchhoff stress tensor. To improve
computational efficiency, the sparse matrix technology and graph theory are used to solve the huge set of linear algebraic
equations in the process of integrating the equations of motion by using the generalized-a method, and an OpenMP based parallel scheme is also introduced. Finally, the effectiveness of the proposed approach is validated
through two numerical examples. One is the static simulation of a single composite laminated plate under gravity and the other
is the dynamic simulations of unfolding process of a satellite system with a pair of complicated antennas. 相似文献
82.
石化行业加热炉效率的提高是降低生产装置能耗的重要手段.传统的加热炉效率计算方式有着实时性不强或数据共享性差等缺点,不利于及时跟踪和调整加热炉工况.本文阐述了通过提取MES系统的实时数据库实时数据,自动计算加热炉热效率和进行实时统计的方法.软件设计灵活、结构性强,通过工艺人员对相关参数的设置,软件自动提取和处理实时数据,可有效地为调整生产做参考依据. 相似文献
83.
84.
环境因素导致无线传感器网络定位存在噪声影响,实质上是非平滑的非线性问题,针对传统粒子滤波算法在处理该问题时精度不高的缺点,提出一种基于后验泊松分布的Monte Carlo-Gaussian重采样粒子滤波算法的无线传感器网络定位算法。首先,基于粒子滤波算法,借鉴扩展卡尔曼滤波算法采用近似后验高斯分布思想,设计了后验泊松分布Monte Carlo-Gaussian重采样粒子滤波器。其次,采用该滤波器设计实现了无线传感器网络定位算法,解决了非平滑非线性的噪声干扰定位问题。最后,分别对滤波器和定位算法的性能进行了对比仿真实验,结果验证了所提算法的有效性。 相似文献
85.
Huan Xie Xin Luo Xiong Xu Haiyan Pan Xiaohua Tong 《International journal of remote sensing》2016,37(8):1826-1844
The successful launch of the Landsat 8 satellite continues the Earth observation of the Landsat series, which has been taking place for nearly 40 years. With the increase in the band number and the improved spectral range compared with the previous Landsat imagery, it will be possible to expand the application of the new Landsat 8 imagery. The purpose of this study is to explore water extraction based on the new Landsat 8 Operational Land Imager (OLI) imagery. According to the specific inland water conditions (clear water, turbid water, and eutrophic water), a number of highly adaptable water indices are assessed for water extraction using Landsat OLI imagery. The results show that clear water is the easiest to extract among the different types of waterbodies, with the highest average accuracy of 97%. The highest-accuracy methods are the automated water extraction index for shadow pixels (AWEIsh), the normalized difference water index using bands 4 and 7 (NDWI47), and the normalized difference water index using bands 3 and 7 (NDWI37), with accuracies of 98.55%, 95.50%, and 96.61%, corresponding to clear water, turbid water, and eutrophic water, respectively. Through the analysis of the different methods for optimal band selection, the seventh band OLI7 (shortwave infrared 2, SWIR-2) of Landsat OLI shows the best performance in water identification. When applying the water indices to water extraction, Otsu’s algorithm has been used to automatically select the water threshold. Using extensive experiments with Otsu’s algorithm and a manual method, it was found that Otsu’s algorithm can replace manual selection and has the ability to select an accurate threshold for water extraction. 相似文献
86.
Jialiang Sun Qiang Tian Haiyan Hu 《Structural and Multidisciplinary Optimization》2017,55(4):1159-1177
A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation. The equivalent static load method is employed to transform the topology optimization of the nonlinear dynamic response of the system into a static one, and evaluated to adapt to the absolute nodal coordinate formulation by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method with the additive operator splitting algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation. In addition, the expert evaluation method of weights based on the grey theory is utilized to define the objective function, and a modified augmented Lagrange multiplier method is proposed to treat the inequality volume constraint so as to avoid the oscillation and drift of the volume. Finally, two numerical examples are provided to validate the proposed methodology. 相似文献
87.
88.
以深圳水库水为原水,选用聚合氯化铝(PAC)、硫酸铝和氯化铁作为气浮工艺的混凝剂进行分析处理,选择出适合深圳水库水的最理想混凝剂.试验结果表明:PAC、硫酸铝、氯化铁三者的最佳投药量分别为1.25、1.25、4mg/L;在各自的最佳投药量下,PAC对浊度、色度、CODMn的去除率都要优于硫酸铝、氯化铁,且使用PAC生成的浮渣量最少.因此选用PAC作为此气浮工艺的混凝剂进行后续研究. 相似文献
89.
Yi Zeng Ning Zhong Yan Wang Yulin Qin Zhisheng Huang Haiyan Zhou Yiyu Yao Frank van Harmelen 《Knowledge and Information Systems》2011,27(3):419-450
Under the context of large-scale scientific literatures, this paper provides a user-centric approach for refining and processing
incomplete or vague query based on cognitive- and granularity-based strategies. From the viewpoints of user interests retention
and granular information processing, we examine various strategies for user-centric unification of search and reasoning. Inspired
by the basic level for human problem-solving in cognitive science, we refine a query based on retained user interests. We
bring the multi-level, multi-perspective strategies from human problem-solving to large-scale search and reasoning. The power/exponential
law-based interests retention modeling, network statistics–based data selection, and ontology-supervised hierarchical reasoning
are developed to implement these strategies. As an illustration, we investigate some case studies based on a large-scale scientific
literature dataset, DBLP. The experimental results show that the proposed strategies are potentially effective. 相似文献
90.