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Search Results: 1 - 10 of 83936 matches for " 易军凯 "
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压电网络板的机电耦合动力学特性
李琳,
北京航空航天大学学报 , 2014, DOI: 10.13700/j.bh.1001-5965.2013.0501
Abstract: 借鉴复合材料结构建模中的均匀化处理方法建立了压电网络板机电耦合动力学方程并对其进行求解,获得了耦合系统的频率特征方程;通过求解频率特征方程发现压电网络板的固有模态以耦合模态对的形式存在;在此基础上对耦合系统的频率特性进行了分析,表明耦合模态对的特征频率值随着电感的变化会出现频率转向现象.进一步通过对系统在频率转向区能量转换规律的研究,揭示了压电网络板中频率转向的意义.最后,分析了压电网络板设计参数对频率转向区特性的影响,为压电网络板的合理设计提供了理论参考.
压电网络板的振动控制原理与控制效果
,李琳
北京航空航天大学学报 , 2014, DOI: 10.13700/j.bh.1001-5965.2013.0641
Abstract: 在给出压电网络板机电耦合动力学方程的基础上对其进行求解,将压电网络板的响应表示为子模态压电系统响应的线性组合.通过分析压电网络板在脉冲激励下子模态压电系统的响应行为,揭示压电网络板可以通过两种途径控制自身振动.基于对传递函数的分析进一步得到子模态压电系统的最优电学参数;在此基础上研究了针对某一阶子模态压电系统设计最优电学参数时,各阶子模态压电系统的响应行为以及压电网络板的多模态控制效果.研究结果表明,压电网络板具有多模态控制效果,特别地,当对板的某一阶次的振动控制具有较高要求时,通过对最优电学参数进行设计,电感电阻并联型压电网络板可满足要求.
面向文本分类的深度置信网络特征提取方法研究
,王超,李辉
- , 2018, DOI: 10.13543/j.bhxbzr.2018.03.014
Abstract: 在对文本分类领域发展现状进行研究的基础上,提出了一种面向文本分类的深度置信网络特征提取方法,通过引入词向量模型和深度置信网络解决传统文本分类方法在文本表示及特征提取方面存在的语义缺失问题,实验结果表明,该方法在文本分类中有更高的准确率。
Abstract:Based on earlier research on the development of text categorization, in this paper, a new feature extraction method for text categorization is proposed. The method solves the semantic loss problem of text representation and feature extraction found in traditional text categorization methods by introducing word embedding and a deep belief network. Experiments show that the new method has higher accuracy than traditional methods in text categorization.
基于压电网络的四边固支板多阶共振抑制
Multi-mode vibration suppression of clamped plates based on piezoelectric networks

李琳,李俊,
- , 2015, DOI: 10.13700/j.bh.1001-5965.2014.0703
Abstract: 摘要 利用四边固支板横向自由振动的精确解作为模态坐标,在模态空间求解了四边固支压电网络板的机电耦合动力学方程.基于对压电网络板在模拟单点激励下谐响应行为的计算分析,得到了控制其各阶共振的压电网络电路元件最优电学参数.电感电阻并联型四边固支压电网络板与四边简支压电网络板不同,其具有多个局部最优电学参数.通过分析这些最优参数对其他阶共振的影响,发现四边固支压电网络板具有多阶共振抑制效果,与电阻相比,该效果对电感更加敏感.电感电阻并联型四边固支压电网络板可以实现比电阻型四边固支压电网络板更好的单模态振动抑制效果,但同时其多模态振动抑制效果会降低.
Abstract:The exact solutions for transverse free vibrations of a clamped plate were adopted as the modal coordinates to solve the given electromechanical coupled kinetic equations of clamped piezo electro mechanical-plate in modal space. After the computational analysis was conducted for harmonic response of the clamped piezo electro mechanical-plate which was stimulated under single-point excitation force, the optimal parameters of electrical components in piezoelectric networks used to suppress different resonances were obtained. For the clamped piezo electro mechanical-plate with parallel resistors and inductors, it has more than one local optimal parameters comparing with a simply supported plate. The clamped piezo electro mechanical-plate has the ability to suppress multimode vibration by analyzing the effectiveness of these optimal parameters on other resonances. In addition, the effectiveness is more sensitive to inductance comparing with resistance. The clamped piezo electro mechanical-plate with parallel resistors and inductors is more effective than piezo electro mechanical-plate only with resistors in reducing resonant response at single resonant frequency, while the multiple-mode vibration suppression effectiveness of it with parallel resistors and inductors will be decreased.
大跨度拱桥静动力试验与结构识别的实践
周云,,陈松柏,伟建
- , 2017,
Abstract: 由于有限元建模中存在不确定性因素的影响,大跨度拱桥初始设计模型的理论分析结果与现场测试数据之间存在一定差异.为了消除模型校验技术中的认知不确定性和随机不确定性,从而更好地进行结构识别,本文以来华大桥和巴溪洲大桥为例,对其中若干关键问题进行了讨论.通过合理地现场勘察与精确的有限元模拟相结合,基于灵敏度分析方法进行不确定性参数筛选,并最终采用最小二乘法进行参数优化,实现了可靠的结构工作状况评估与响应预测.研究包括现场静动力试验、有限元模拟、模型校验、响应预测和校验合理性评估等.基于精确建模和模态参数的校验技术可以有效地减小有限元模型与现场静动力试验结果之间的误差,使用未经试验结果校验的设计模型,进行两座桥梁校验系数的评估,分别存在着21%和23%的误差.
Various uncertainties of the FE modeling may have significant impact on structural identification and result in obvious discrepancy between FE model analysis and field test results. In order to eliminate epistemic uncertainty and aleatory uncertainty during model calibration procedure, which contributes to achieve reliable condition assessment and response prediction, two long-span bridges were taken for examples, and several critical issues were discussed. By means of field inspection and blueprint review, simultaneously combined with the precise modeling, uncertain parameter selection was carried out based on sensitivity analysis, and parameter optimization was eventually performed by the least square method to complete the working condition assessment and response prediction. Research in this paper consists of in-situ experiments, precise finite element modeling, model calibration, and model admissibility check. Discrepancies between FE model and field test results can be mitigated by efficient model calibration method, and initial design model generally shows 20% and 23% relative difference.
图像的SIFT特征二阶检索算法
,陈龙龙,姜大光
- , 2016, DOI: 10.13543/j.bhxbzr.2016.04.014
Abstract: 提出了用图像SIFT特征二阶检索算法实现相似图像检索。首先对图像进行SIFT特征提取,然后利用词袋算法通过K-Means聚类出特征词并建立特征词频表,最后基于词频表通过二阶检索算法实现相似图像匹配。二阶检索分两步:第一步实现特征分布结构的相似检索;第二步根据两张图像对应特征点落于同一特征类的数量与图像自身特征点数的比例来实现图像的精确检索,提高图像检索的准确率。实验结果表明,该方法具有较高的查全率,同时在查询效率上也具有很好的表现。
Abstract:This paper proposes a second-order retrieval algorithm, which can be used to retrieve similar images. The image SIFT features are first extracted. The frequency table of characteristic words is then built by K-Means clustering and a bag of words algorithm. Finally, based on the word frequency table, similar images can be retrieved by means of a second-order retrieval algorithm. The first step is retrieving the images that have similar distribution characteristics in their structure. The second retrieval step involves accurate retrieval of images according to the proportion of the corresponding feature points that belong to the same class. The experimental results show that this method has both a good recall factor and high query efficiency. 
基于距离的相似最近邻搜索算法研究
姜大光,孙贺娟,
- , 2017, DOI: 10.13543/j.bhxbzr.2017.05.015
Abstract: 为了提高相似最近邻搜索(ANN)算法的精度,提出了一种在度量空间下基于距离的相似最近邻搜索算法-优化的VP森林(OVF)算法。在传统VP树(VT)算法的基础上,首先采用改进的选择优势点的方法,通过从数据集采样优势点候选集,对其进行评估,选取其中区分度大的点作为优势点;然后提出构建多棵VP树的新方法,改进距离优势点远的子树中最近邻不紧凑问题;接着提出使用优先队列与剪枝搜索方法结合的新搜索方法查找最近邻,减少了很多不必要的距离计算。最后通过实验结果表明,本文方法在数据维度、数据集大小、返回不同邻居个数、不同的距离函数及建树个数方面精度有了很大的提高。
Abstract:In order to improve the accuracy of approximate nearest neighbor (ANN) algorithms, this paper proposes an approximate nearest neighbor algorithm based on distance in metric space-the optimized vantage point (VP) forest algorithm (OVF). Starting from the traditional VP tree algorithm, we first adopted an improved method for selecting vantage points, evaluated the vantage point candidate set sampled from the data set, and selected the point which had the biggest degree of differentiation as the vantage point. We then put forward a new method of building multiple VP trees, overcoming the problem of the nearest neighbors not being compact in the sub-tree, which further distances the vantage point. Finally, we proposed a new search method to find the nearest neighbors by combining a priority queue and a pruning method, which significantly reduces unnecessary distance calculations. The experimental results show that the algorithm proposed in this paper gives a large enhancement in precision in terms of the data dimension, the size of the data set, the return of different numbers of neighbors, the different distance functions, and building different number of trees.
原创科技复杂网络的反演模型研究
,闫拴,万静,杨光,李琳,张勇
- , 2016, DOI: 10.13543/j.bhxbzr.2016.02.019
Abstract: 为减少先进科技跟踪成本,研究了原创科技复杂网络的反演模型,将传统的科技信息直接获取变为间接推理。 该模型首先以约束反演方法来提取复杂网络中各个节点的社会属性和技术属性,并对其进行量化;然后研究属性间关联关系的计算方法,形成统一的分值矩阵模型,并量化复杂网络模型的各个节点间的权值;最后对模型进行分析形成多种优化目标的计算方法,并采用约束反演推理策略进行复杂网络最优路径求解,其中引入变量事件分类以加快反演速度。 实验结果表明,该模型能够快速反演出先进科技的来源,并具有良好的可信度。
Abstract:In an attempt to reduce tracking costs for advanced science, an inversion model of an original science complex network has been developed in which indirect reasoning is used rather than obtaining information directly.The model first extracts social and technical attributes of each node, sampled according to the weight of each node. Secondly the method of calculating the relationship between those properties is provided. Applying a unified score matrix model allows the complex weight of each edge of the network model to be calculated. Finally several optimization methods are used. We can combine the constrained inversion process with several reasoning approaches to establish an optimal path for the complex network. Moreover, our method speeds up the inversion by applying a variable event classification. The experimental results show that the model can find the sources of advanced technology in reasonable time and also provide sufficient accuracy.
拟南芥CBF1基因植物表达载体构建及其野生蕉的遗传转化
,胡春华,魏岳荣,,邵秀红
湖南农业大学学报(自然科学版) , 2011,
Abstract: 从拟南芥中克隆CBF1基因,转入到植物表达载体pBI121的XbaI和SacI位点,得到中间重组质粒pBI121-CBF1,用EcoRI和HindⅢ将35S启动子与CBF1基因从pBI121-CBF1切下,转入到植物表达载体pCAMBIA1301中,构建植物表达载体p1301-CBF1。将构建的植物表达载体转入农杆菌EHA105,采用农杆菌介导法转化野生蕉胚性悬浮细胞,经GUS组织化学染色和PCR鉴定,证明CBF1基因已转入野生蕉中。。
论私法上公序良俗条款的基本功能

比较法研究 , 2006,
Abstract:
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