不等权泛组合运算模型研究

实际复杂系统中的各因素一般具有不同的权重,针对现有的泛组合运算模型描述的是一种理想的等权情况,给出了两种广义加权算子模型,并据此提出了一种不等权泛组合运算模型,从而可以更准确地处理复杂系统中各因素间关系的不确定性问题.     

Control allocation technology based on fault diagnosis for the unmanned aerial vehicle system subject to physical constraints and fault reconfiguration mismatch

The problem of the system robustness subject to physical constraints and mismatched fault reconstruction is discussed in this paper. In order to facilitate the design, a four-rotor unmanned aerial vehicle (UAV) system model was selected for research. First, the control allocation model of the nonlinear UAV system with disturbances is shown in the paper. Secondly, a weighted pseudo-inverse method based on adaptive weights is proposed, which reduces the impact of physical constraints on the system. After that, a dynamic weight control allocation method based on the fault efficiency matrix is designed. The weight matrix can dynamically adjust the control distribution law according to the fault estimation value provided by the observer. Then, a dynamic adaptive control allocation method for faults and physical constraints is carried out by combining adaptive weights and dynamic weights. Finally, a simulation example is presented to further illustrate the effectiveness of the algorithm proposed in this paper.     

基于云模型和余弦跳跃权重的改进蛙跳算法

标准蛙跳优化算法(SFLA)有寻优精度低和易陷入局部收敛区域的缺点, 为提高其性能, 提出一种基于云模型局部搜索和余弦跳跃权重更新位置的改进蛙跳算法(CSFLA). 首先通过Tent混沌映射和反向学习生成种群, 使种群的分布更均匀, 利用云模型的正态特性对子群中的优秀个体的所在区域进行探索. 同时, 对种群中其他个体引入基于余弦函数的跳跃步长权重, 使该权重在整个迭代过程中由高以不同的速率下降, 提高种群的全局搜索能力. 最后, 将CSFLA与多个优化算法在不同类型的测试函数上进行了比较. 结果表明, CSFLA具有更好的收敛速度和精度, 能有效找出全局最优解. 并且将改进算法应用至旅行商问题, 该算法可以找到总路程更短的路线.     

基于词项扩展的XML信息检索反馈技术

为提高XML信息检索的查询准确率,提出一种基于词项扩展的XML信息检索反馈技术.利用词项所在节点的语义权重、词项与查询词间的相邻频度、共现程度,评估词项权重并排序,取权重较大的词项对初始检索词进行扩展,给出各因子的计算方法.在Wikipedia2009数据集上的实验结果表明,扩展后的查询准确率较高.     

带权定性影响图

定性影响图是具有精确概率和效用的影响图的定性抽象。在定性影响图中,节点之间的影响关系使用定性符号描述,这种符号描述简化了不确定知识的表示,降低了影响图建模的难度,加速了不确定知识的推理。但是,定性影响图在抽象过程中损失了部分信息,导致定性影响图在评价过程中会产生不确定结果,阻碍了定性影响图的广泛应用。以加权的思想扩展定性影响图,使扩展的定性影响图中每个定性影响都带有一个表示节点间影响强弱的数值权值,在评价过程中根据定性影响权值的比较来减少不确定结果的产生,从而扩大定性影响图的应用范围。     

An e-commerce performance assessment model: Its development and an initial test on e-commerce applications in the retail sector of China

We developed a performance assessment model for e-commerce; it included indicators, indicator weights, and evaluation methods. The model has seven methods of assessing e-commerce performance and uses four criteria to compare and select the appropriate one for a particular situation. This model was tested in the retail sector of China. According to the data collected from 70 Chinese retailers, 16 indicators of e-commerce performance consisted of four constructs: marketing and sales, customer service, supply chain efficiency, and financial performance. The indicators for those constructs provide a comprehensive measurement of performance. Then weights were assigned for each indicator using a majority aggregation method. Comparison of the results from seven evaluation methods showed that discordance analysis and simple additive weighting were the best evaluation methods for the enterprises we had sampled.     

Weighted dynamic time warping for time series classification

Dynamic time warping (DTW), which finds the minimum path by providing non-linear alignments between two time series, has been widely used as a distance measure for time series classification and clustering. However, DTW does not account for the relative importance regarding the phase difference between a reference point and a testing point. This may lead to misclassification especially in applications where the shape similarity between two sequences is a major consideration for an accurate recognition. Therefore, we propose a novel distance measure, called a weighted DTW (WDTW), which is a penalty-based DTW. Our approach penalizes points with higher phase difference between a reference point and a testing point in order to prevent minimum distance distortion caused by outliers. The rationale underlying the proposed distance measure is demonstrated with some illustrative examples. A new weight function, called the modified logistic weight function (MLWF), is also proposed to systematically assign weights as a function of the phase difference between a reference point and a testing point. By applying different weights to adjacent points, the proposed algorithm can enhance the detection of similarity between two time series. We show that some popular distance measures such as DTW and Euclidean distance are special cases of our proposed WDTW measure. We extend the proposed idea to other variants of DTW such as derivative dynamic time warping (DDTW) and propose the weighted version of DDTW. We have compared the performances of our proposed procedures with other popular approaches using public data sets available through the UCR Time Series Data Mining Archive for both time series classification and clustering problems. The experimental results indicate that the proposed approaches can achieve improved accuracy for time series classification and clustering problems.     

A new fuzzy decision-making procedure applied to emergency electric power distribution scheduling

In this paper a new fuzzy decision-making procedure is developed. Two levels of weightings, called upper and lower weights, are proposed to calculate the fuzzy weightings of different criteria. The preference table is introduced to calculate the upper and lower weights. Also a new method is developed to determine the expected preference values of different alternatives. These values are used for generating the priority list of alternatives. The procedure is applied for providing an emergency electric power distribution, scheduling time table. The IEEE 14-bus standard system and a 14-bus system with four power plants are considered as case studies. Using fuzzy decision-making procedure, the regions with more priorities are more connected to the distribution net, while the maximum consumption criterion is also reasonably respected.     

水贫困指数在河西走廊三大内陆河流域的应用

水贫困指数提供了一种简单、易行的水资源评价方法,它通过资源、途径、能力、利用和环境5个方面来定量评价区域水资源的相对水平。运用主客观组合赋权法确定各分指标的权重,对河西走廊三大内陆河流域的水贫困指数进行了研究。结果表明:黑河流域、疏勒河流域、石羊河流域的水贫困指数分别为39.4、66.0、36.6,评价结果与客观情况基本相符。     

一个A_∞权类的特征刻画及其应用

建立了A∞权类的一个特征刻画并且定义了一类变形的John-Strmberg局部极大算子,应用所建立的特征刻画证明了这类极大算子的Lp(Rn)(0相似文献