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基于自适应修正模型的飞行器外流场三维计算方法
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作者 彭革 徐兴贵 +4 位作者 李忠武 任维贺 李康 郑国宪 邓红艳 《计算机科学》 CSCD 北大核心 2024年第S01期1135-1143,共9页
目前飞行器外流场仿真方法中存在流体可压缩性判断依赖经验知识以及目标外流场三维仿真缺乏封闭约束条件的问题。对此,提出一种基于自适应修正模型的三维外流场数值计算方法。根据飞行器外流场变异系数先验知识,采用加权平均N-S方程表... 目前飞行器外流场仿真方法中存在流体可压缩性判断依赖经验知识以及目标外流场三维仿真缺乏封闭约束条件的问题。对此,提出一种基于自适应修正模型的三维外流场数值计算方法。根据飞行器外流场变异系数先验知识,采用加权平均N-S方程表示可压缩流体物理量分布,同时利用膨胀压缩修正和激波不定项修正两种策略自适应地修正k-ε湍流模型的可压缩性约束条件,并采用壁面函数对近壁区进行近似计算修正约束条件。以某型号无人机外流场分布三维建模仿真实验,结果表明:当飞行器速度达到1.5马赫时,可压缩修正模型出现边界约束条件临界值,所提自适应可压缩修正算法能有效判断气体可压缩性的变化并提升流体分布计算的准确性。 展开更多
关键词 湍流 流场三维仿真 密度加权平均数值模拟 可压缩修正
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自适应抽指加权技术
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作者 陈晓阳 王永安 +1 位作者 孟腾飞 曹玉 《压电与声光》 CAS 北大核心 2022年第2期250-252,共3页
在传统的抽指加权技术基础上,该文提出了一种自适应抽指加权技术。通过计算确定抽指加权的起始位置和加权数值,能对切趾换能器进行部分指条的抽指加权。研究结果表明,根据该文提出方法研制的一款声表面波滤波器,其频率为61.60 MHz,-1 d... 在传统的抽指加权技术基础上,该文提出了一种自适应抽指加权技术。通过计算确定抽指加权的起始位置和加权数值,能对切趾换能器进行部分指条的抽指加权。研究结果表明,根据该文提出方法研制的一款声表面波滤波器,其频率为61.60 MHz,-1 dB相对带宽为3.7%,带外抑制大于45 dB,矩形度为1.4,器件的综合性能得到改善。 展开更多
关键词 抽指加权 自适应 切趾 加权位置 加权数值 声表面波滤波器
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基于多特征融合的羽毛球扣杀动作轨迹跟踪
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作者 何佳佳 薛诗乐 何建强 《信息技术》 2023年第11期68-72,共5页
羽毛球扣杀动作专业性较强、动作轨迹较为复杂,难以捕捉,因此提出一种基于多特征融合的羽毛球扣杀动作轨迹跟踪方法。构建轨迹观测模型,提取羽毛球扣杀动作的目标特征和距离特征;计算实际轨迹观测值与估计轨迹观测值间的巴氏距离,采用... 羽毛球扣杀动作专业性较强、动作轨迹较为复杂,难以捕捉,因此提出一种基于多特征融合的羽毛球扣杀动作轨迹跟踪方法。构建轨迹观测模型,提取羽毛球扣杀动作的目标特征和距离特征;计算实际轨迹观测值与估计轨迹观测值间的巴氏距离,采用分布序列函数表现形式,将复杂的跟踪轨迹转换为基于贝叶斯状态的运动曲线推理问题;计算每个时刻下跟踪轨迹的状态参数,凭借帧数连续性实时状态分布结果完成轨迹跟踪。仿真实验证明,所提方法轨迹融合效果较好,跟踪曲线稳定性较强,可实现羽毛球扣杀动作的有效跟踪。 展开更多
关键词 多特征融合 加权数值 巴氏距离 高斯分布 分布序列函数
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网页自动分类中特征权重计算方法的改进 被引量:2
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作者 谭金波 杨晓江 李艺 《情报学报》 CSSCI 北大核心 2008年第1期56-61,共6页
目前,在网页分类中,对HTML主要结构特征进行加权的常用方法是绝对数值加权方法。这种方法的缺点是加权系数为定值,其对长文本和短文本所起的作用不同,使得结构特征对正文的影响随着正文长度的增加而削弱。针对该缺点,本文提出了一... 目前,在网页分类中,对HTML主要结构特征进行加权的常用方法是绝对数值加权方法。这种方法的缺点是加权系数为定值,其对长文本和短文本所起的作用不同,使得结构特征对正文的影响随着正文长度的增加而削弱。针对该缺点,本文提出了一种改进型加权方法,即相对数值加权方法。通过网页层次分类的实验,比较了这两种方法对单个标签域以及多个标签域结合的分类性能。实验结果表明,相对数值加权方法能有效提高分类的精确度,并且效果优于绝对数值加权方法。 展开更多
关键词 网页分类 层次分类 特征项 权重算法 相对数值加权
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基于电场数值加权的跨介质元胞共形新技术 被引量:4
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作者 孙亚秀 姜庆辉 《物理学报》 SCIE EI CAS CSCD 北大核心 2013年第16期129-137,共9页
针对时域有限差分法处理跨介质元胞现有共形技术中存在误差大、平行方向未被包含等问题,提出一种利用电场数值加权法来进行跨介质元胞共形计算的新算法.该算法不再对介电常数ε做加权平均处理,而是根据中值定理对时域有限差分法真正的... 针对时域有限差分法处理跨介质元胞现有共形技术中存在误差大、平行方向未被包含等问题,提出一种利用电场数值加权法来进行跨介质元胞共形计算的新算法.该算法不再对介电常数ε做加权平均处理,而是根据中值定理对时域有限差分法真正的求解分量电场强度进行权值选择,并将权值乘入积分路径中.该方法同时考虑了跨介质安培环路元胞与跨介质法拉第环路元胞对结果带来的不连续影响,而且对介质界面与元胞中场分量的各种位置关系均能应用,通用性强、精度高且易于实现.利用介质填充圆波导作为数值模型来进行理论数值计算和仿真验证,比较不同共形方法的二维TE模式的特征根与理论值的偏差以及由共形技术所带来的各向相异性.数值结果表明,本文所提出算法求得的特征根最接近理论值,而且造成的各向相异性更小,从而验证了该算法在处理跨介质元胞时的有效性. 展开更多
关键词 时域有限差分 电场数值加权 二维TE模式 跨介质元胞
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Importance of Weighting for Multi-Variable Habitat Suitability Index Model: A Case Study of Winter- Spring Cohort of Ommastrephes bartramii in the Northwestern Pacific Ocean 被引量:12
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作者 GONG Caixia CHEN Xinjun +1 位作者 GAO Feng CHEN Yong 《Journal of Ocean University of China》 SCIE CAS 2012年第2期241-248,共8页
Weighting values for different habitat variables used in multi-factor habitat suitability index (HSI) modeling reflect the relative influences of different variables on distribution of fish species. Using the winter-s... Weighting values for different habitat variables used in multi-factor habitat suitability index (HSI) modeling reflect the relative influences of different variables on distribution of fish species. Using the winter-spring cohort of neon flying squid (Ommastrephes bartramii) in the Northwestern Pacific Ocean as an example, we evaluated the impact of different weighting schemes on the HSI models based on sea surface temperature, gradient of sea surface temperature and sea surface height. We compared differences in predicted fishing effort and HSI values resulting from different weighting. The weighting for different habitat variables could greatly influence HSI modeling and should be carefully done based on their relative importance in influencing the resource spatial distribution. Weighting in a multi-factor HSI model should be further studied and optimization methods should be developed to improve forecasting squid spatial distributions. 展开更多
关键词 weighting multi-factors habitat suitability index model Ommastrephes bartramii Northwestern Pacific Ocean
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Method of Semi Analytic Perturbation Weighted Residuals for Nonlinear Bending of Shallow Shells
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作者 李云飞 黄怡筠 《Journal of Beijing Institute of Technology》 EI CAS 2000年第1期15-19,共5页
The semi? analytic perturbation weighted residuals method was used to solve the nonlinear bending problem of shallow shells, and the fifth order B spline was taken as trial function to seek an efficient method for n... The semi? analytic perturbation weighted residuals method was used to solve the nonlinear bending problem of shallow shells, and the fifth order B spline was taken as trial function to seek an efficient method for nonlinear bending problem of shallow shells. The results from the present method are in good agreement with those derived from other methods. The present method is of higher accuracy, lower computing time and wider adaptability. In addition, the design of computer program is simple and it is easy to be programmed. 展开更多
关键词 shallow shell nonlinear bending perturbation method weighted residuals method spline function
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Kinetic Study on Extraction of Red Pepper Seed Oil with Supercritical CO_2 被引量:4
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作者 王金艳 王玉琪 +4 位作者 郑岚 倪士峰 范召运 姚瑞清 陈开勋 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第1期44-50,共7页
A mathematical model for extraction of red pepper seed oil with supercritical CO2was proposed.Some factors influencing the process were investigated,including operation pressure,temperature and extraction yield Xe(%).... A mathematical model for extraction of red pepper seed oil with supercritical CO2was proposed.Some factors influencing the process were investigated,including operation pressure,temperature and extraction yield Xe(%).The model was solved by the method of weighted residuals and used to simulate the process numerically.The kinetic equation is expressed as Xe16.8606exp(t/9.98177)16.95457 and the simulation results are in excellent agreement with the experimental data.The optimal operating parameters are 30 MPa,318 K and 60 min. 展开更多
关键词 supercritical C02 red pepper seed mathematical model
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Three-dimensional stability of landslides based on local safety factor 被引量:4
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作者 YANG Tao Man-chu Ronald YEUNG +2 位作者 YANG Bing LIU Yong-jiang YANG Yan-xin 《Journal of Mountain Science》 SCIE CSCD 2016年第9期1515-1526,共12页
Unlike the limit equilibrium method(LEM), with which only the global safety factor of the landslide can be calculated, a local safety factor(LSF) method is proposed to evaluate the stability of different sections of a... Unlike the limit equilibrium method(LEM), with which only the global safety factor of the landslide can be calculated, a local safety factor(LSF) method is proposed to evaluate the stability of different sections of a landslide in this paper. Based on three-dimensional(3D) numerical simulation results, the local safety factor is defined as the ratio of the shear strength of the soil at an element on the slip zone to the shear stress parallel to the sliding direction at that element. The global safety factor of the landslide is defined as the weighted average of all local safety factors based on the area of the slip surface. Some example analyses show that the results computed by the LSF method agree well with those calculated by the General Limit Equilibrium(GLE) method in two-dimensional(2D) models and the distribution of the LSF in the 3D slip zone is consistent with that indicated by the observed deformation pattern of an actual landslide in China. 展开更多
关键词 Landslide stability Local safety factor Stability analysis method Slip mechanism
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A Monte Carlo Model of Light Propagation in Nontransparent Tissue 被引量:2
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作者 姚建铨 朱水泉 +1 位作者 胡海峰 王瑞康 《Transactions of Tianjin University》 EI CAS 2004年第3期209-213,共5页
To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and ho... To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and how light propagates in bio-tissue is analyzed in virtue of mathematics and physics equations. The relations,in which light intensity of Class 1 and Class 2 light with different wavelengths changes with their permeation depth,and in which Class 1 light intensity (signal light intensity) changes with the probing depth, and in which angularly resolved diffuse reflectance and diffuse transmittance change with the exiting angle, are studied. The results show that Monte Carlo simulation results are consistent with the theory data. 展开更多
关键词 optical coherence tomography(OCT) mathematics and physics equations bio-tissue Monte Carlo model photon cluster weight
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基于权重评估的主干光节点选址方法
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作者 陈齐 《中国有线电视》 2015年第10期1181-1183,共3页
提出基于权重评估的主干光节点的选址方法,准确地把握了影响主干光节点选址的几个关键因素,并且结合数值加权计算方法,高效地确定了合适的主干光节点。
关键词 权重评估 光节点 数值加权计算
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计算力学的研究现状与发展前景 被引量:4
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作者 张伟林 《安徽建筑工业学院学报(自然科学版)》 2001年第2期7-12,共6页
对计算力学的研究现状作了分析 ,介绍了计算力学中的主要方法 ,其中包括有限差分法、有限元法、边界元法、加权残数法和有限元线法等。又从算法的研究方面讨论了计算力学的研究进展 ,并探讨了计算力学今后的发展趋势。
关键词 计算力学 有限差分法 有限元法 边界元法 加权残数法 有限元线法 数值与解析结合法 结构优化设计 并行算法
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Novel Adaptive Weighted Mean Filter
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作者 程学珍 张京钊 程凤菊 《Journal of Measurement Science and Instrumentation》 CAS 2011年第2期116-119,共4页
Based on the advantages and disadvantages of the standard median filter and the standard wean filter, a new Adaptive Weighted Mean Filter(AWFM) was proposed in this paper. The filter window's size of every pixel wa... Based on the advantages and disadvantages of the standard median filter and the standard wean filter, a new Adaptive Weighted Mean Filter(AWFM) was proposed in this paper. The filter window's size of every pixel was adaptively adjusted. Then the suspidons noise points were examined by certain rules. After that, the authors calculate the weighting factors of the pixels by weighting function which was canstructed according to the differences between their gray values and the median value of all elements in the window. Finally they use the weighted average of gray values to substitute the gray value of the central pixel in the window. The results indicate that this filtering method is not only effective for impulse noise like median filter, but also better than the standard median filters. Compared with conventional filter, this filter methed can effectivdy suppress the mixture noise of images, and protect image's details well. 展开更多
关键词 image filter mixed noise weighted mean noise detect tion median jilter
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New Double Integrals Weighted Cebysev Type Inequalities
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作者 A. Guezane-Lakoud F. Aissaoui 《Journal of Mathematics and System Science》 2012年第5期286-291,共6页
In the last years, the theory of integral inequalities are playing a very significant role in all fields of mathematics, many monographs have been devoted to this subject and present a very active and attractive field... In the last years, the theory of integral inequalities are playing a very significant role in all fields of mathematics, many monographs have been devoted to this subject and present a very active and attractive field of research, the applications of integral inequalities have known a great development in many branches of mathematics in statistics, differential equations and numerical integration, The aim of this paper is to establish new extension of the weighted montgomery identity for double integrals then used it to establish new t^eby^evtype inequalities. 展开更多
关键词 Cebysev type inequalities montgomery identity weighted peanokemel double integrals Cebysevinequalities weightedtCebysev inequalities ostrowski inequality.
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Universality of Competitive Networks in Complex Networks 被引量:1
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作者 GUO Jinli FAN Chao JI Yali 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2015年第3期546-558,共13页
The paper proposes a model which helps to investigate the competitive aspect of real networks in quantitative terms. Through theoretical analysis and numerical simulations, it shows that the competitive model has the ... The paper proposes a model which helps to investigate the competitive aspect of real networks in quantitative terms. Through theoretical analysis and numerical simulations, it shows that the competitive model has the universality for a weighted network. The relation between parameters in the weighted network and the competitiveness in the competitive network is obtained by theoretical analysis. Based on the expression of the degree distribution of the competitive network, the strength and degree distributions of the weighted network can be calculated. The analytical solution reveals that the degree distribution of the weighted network is correlated with the increment and initial value of edge weights, which is verified by numerical simulations. Moreover, the evolving pattern of a clustering coefficient along with network parameters such as the size of a network, an updating coefficient, an initial weight and the competitiveness are obtained by further simulations. 展开更多
关键词 Competitive network complex network scale-free network weighted network.
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FROM UNWEIGHTED TO WEIGHTED GENERALIZED FAREY ORGANIZED TREE AND THE PYRAMID NETWORKS 被引量:1
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作者 Yong LI·Jinqing FANG·Qiang LIU China Institute of Atomic Energy,Beijing 102413,China. 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2010年第4期681-700,共20页
Generalized Farey tree network (GFTN) and generalized Farey organized pyramid network (CFOPN) model are proposed, and their topological characteristics are studied by both theoretical analysis and numerical simula... Generalized Farey tree network (GFTN) and generalized Farey organized pyramid network (CFOPN) model are proposed, and their topological characteristics are studied by both theoretical analysis and numerical simulations, which are in good accordance with each other. Then weighted GFTN is studied using cumulative distributions of its Farey number value, edge weight, and node strength. These results maybe helpful for future theoretical development of hybrid models. 展开更多
关键词 Generalized Farey organized pyramid network topological properties weighted generalized Farey tree network.
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纸张行情分析
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《瓦楞纸箱商情》 2004年第01M期31-32,共2页
纸张行情分析趋势图中,所列价格指数为抽样调查加权平均数值,并不代表某品牌现时价格。
关键词 纸张市场 行情分析趋势图 价格指数 加权平均数值 废纸 纸板
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Randomly Weighted LAD-Estimation for Partially Linear Errors-in-Variables Models
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作者 Xiaohan YANG Rong JIANG Weimin QIAN 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2015年第4期561-578,共18页
The authors consider the partially linear model relating a response Y to predictors (x, T) with a mean function x^Tβ0 + g(T) when the x's are measured with an additive error. The estimators of parameter β0 are... The authors consider the partially linear model relating a response Y to predictors (x, T) with a mean function x^Tβ0 + g(T) when the x's are measured with an additive error. The estimators of parameter β0 are derived by using the nearest neighbor-generalized randomly weighted least absolute deviation (LAD for short) method. The resulting estimator of the unknown vector 30 is shown to be consistent and asymptotically normal. In addition, the results facilitate the construction of confidence regions and the hypothesis testing for the unknown parameters. Extensive simulations are reported, showing that the proposed method works well in practical settings. The proposed methods are also applied to a data set from the study of an AIDS clinical trial group. 展开更多
关键词 Partially linear errors-in-variables LAD-estimation Randomly weighted method Linear hypothesis Randomly weighted LAD-test
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