基于逆系统迭代学习观测器的故障调节方法

针对一类满足Lipschitz条件的多输入多输出非线性可逆系统执行器故障问题,提出了一种基于迭代学习观测器的逆系统内模故障调节方法。引入PD型迭代学习策略,设计了迭代学习故障诊断观测器,用于对执行器未知时变故障进行快速、准确估计。根据故障估计值,结合逆系统方法对逆模型进行补偿,使得补偿后的逆模型与非线性被控对象串联仍为伪线性系统;再结合内模控制实现了伪线性系统的容错控制。最后,通过仿真算例验证了该方案的有效性。     

产品设计时间智能预测方法的研究

首先利用质量功能配置技术从设计要求中提取产品特征，从而确定影响设计任务所需时间的因素集；其次给出一种模糊神经网络模型来融合数据并实现时间的预测，该模型通过模糊综合评判来精简结构；最后通过注塑模具设计应用表明了该智能预测方法的有效性和可行性．     

A directed failure causality network (DFCN) based method for function components risk prioritization under interval type-2 fuzzy environment

Failure risk prioritization of function components plays a key role in the process to redesign a mechanical product. However, the failure causality relationships (FCRs) among failure modes of components are often ignored in the existing design risk assessment methods, leading to inaccurate risk prioritization results. A failure mode in one component can be the cause of a failure mode in another component, and a failure mode with low chance of failure may result in another failure mode with high chance of failure through propagation among failure modes. Thus, the ultimate effects of each failure mode should be determined by considering the effects of failure propagations. In this research, a directed failure causality network (DFCN) model considering FCRs is proposed to describe the FCRs and to predict risks of the designed product. In addition, uncertainties of linguistic terms in evaluation are also considered in the developed model, because linguistic terms are more suitable and natural than quantitative numbers for design engineers to assess design risks based on their knowledge. To describe these uncertainties, interval type-2 fuzzy set is employed to model the designers’ subjective linguistic terms for determining the weights of edges and weights of vertices in the DFCN. A case study for failure risk prioritization of components in redesign of a large tonnage crawler crane (LTCC) is implemented to demonstrate the effectiveness of the proposed method.     

Estimation of a flexible simple linear model for interval data based on set arithmetic

The estimation of a simple linear regression model when both the independent and dependent variable are interval valued is addressed. The regression model is defined by using the interval arithmetic, it considers the possibility of interval-valued disturbances, and it is less restrictive than existing models. After the theoretical formalization, the least-squares (LS) estimation of the linear model with respect to a suitable distance in the space of intervals is developed. The LS approach leads to a constrained minimization problem that is solved analytically. The strong consistency of the obtained estimators is proven. The estimation procedure is reinforced by a real-life application and some simulation studies.     

A systematic knowledge-based method for design of transformable product

A transformable product can perform different functions or change functionality by changing its physical structure. It is formed by integration of different components whose states can be transformed each other. However, there is a lack of systematic methods to guide design of the transformable product. In order to improve the design efficiency of transformable products, a large number of products are studied in this research to build a case base of transformation parameters and transformation principles for the design knowledge. A systematic design process is proposed to apply the design knowledge. The transformation design problem is first mapped from the problem domain to the knowledge domain expressed by transformation parameters. A general solution is then obtained in the knowledge domain. A multi-classification support vector machine is used to train a model of the transformation recommendation based on transformation parameters. Finally, the general solution is mapped into the problem domain for the specific solution using the analogy design. The effectiveness of the method is verified in the design of a self-propelled boom sprayer.     

基于Bootstrap区间估计的中药指纹图谱相似度阈值确定方法研究

利用指纹图谱相似度评价中药质量时,色谱指纹图谱样本的数量有限。小样本条件下指纹图谱相似度值的分布难以满足正态分布或近似正态分布,不适合直接利用传统的区间估计方法来确定相似度的阈值。本文利用Bootstrap方法扩增样本,建立了小样本条件下的指纹图谱相似度阈值确定方法,并通过3个具体实例说明指纹图谱相似度阈值确定的具体过程。首先通过Bootstrap方法扩增样本,然后利用单侧区间估计方法确定相似度下限,得到相似度的阈值。以上3个实例说明了用该方法建立中药指纹图谱相似度阈值的合理性和可行性。此方法适用于由不同相似度计算方法所得相似度值。本文从理论、技术和应用的角度阐述了确定中药指纹图谱相似度阈值的方法,该方法将对指纹图谱技术的推广应用产生积极作用。     

一种基于区间数判断矩阵的加权AlP群决策方法

针对决策过程中区间数更适合表达决策者对候选方案的偏好程度,基于区间数判断矩阵,综合考虑决策者个体权重,扩展“和积法”,应用“相对熵”的概念,提出了一种加权个体方案权重集结的群体决策方法．该方法将中间结果转化为实数型再进行集结,避免了决策者判断信息的丢失．最后,通过算例说明了该方法的可行性和有效性．     

A product design method for form and color matching based on aesthetic theory

Form and color matching design are vital links in product design. Recently, many scholars have focused on quantifying visual aesthetics to improve design efficiency in form or color matching design activities. However, few scholars have considered both form and color matching. Therefore, we propose a more comprehensive and practical design model based on the aesthetics theory of form and color matching. This model includes 3 phases: preparation (Phase I), form design (Phase II), and color matching design (Phase III). In Phase I, the target product's functional system and design objectives are clarified. In Phase II, the spatial layouts of the target product are analysed, and several reasonable layouts are designed in detail. Finally, the form with the highest aesthetic measurement is selected from alternatives using the modified equilibrium formula and questionnaire. In Phase III, a group of colors conforming to the target imagery is selected from a color palette. Meanwhile, a set of appropriate observation angles are chosen using an expert questionnaire. Subsequently, three-color combinations with higher color harmony are filled into images with different observation angles. Finally, the aesthetics of color matching schemes are obtained using the formula of color matching, and the scheme with a higher average value of the aesthetic measurement from all observation angles is considered the best scheme. This paper takes the fresh food vehicle and leafless fan as the cases. The best form and color matching scheme are obtained using the formula of aesthetic measurement and verified with an expert questionnaire. The result shows consistency between the results of the quantization formula and the expert questionnaire, which confirms the effectiveness of this design model. The proposed design model could improve the design efficiency and ensure the products' visual aesthetics.     

基于近似随进占优的概率区间数信息多属性决策方法

针对传统区间数包含信息量太少,导致决策结果具有很大不确定性的问题,提出了基于VIKOR的概率区间数多属性决策方法。该方法首先将概率信息引入区间数,定义概率区间数的运算规则和集结算子。接着基于近似随机占优理念,定义了一种新的主客观结合的占优度,在此基础上确立了概率区间数的比较规则。最后将专家给出的概率区间数决策矩阵转化为占优度矩阵,并利用 VIKOR 方法对其求解。算例分析表明,该方法对概率分布的缓急变化具有很好的稳定性,而对于概率分布的偏态趋势变化具有敏感性。得到的决策结果在与传统方法一致的基础上更为准确。     

A method to optimize the scope of a software product platform based on end-user features

ContextDue to increased competition and the advent of mass customization, many software firms are utilizing product families – groups of related products derived from a product platform – to provide product variety in a cost-effective manner. The key to designing a successful software product family is the product platform, so it is important to determine the most appropriate product platform scope related to business objectives, for product line development.AimThis paper proposes a novel method to find the optimized scope of a software product platform based on end-user features.MethodThe proposed method, PPSMS (Product Platform Scoping Method for Software Product Lines), mathematically formulates the product platform scope selection as an optimization problem. The problem formulation targets identification of an optimized product platform scope that will maximize life cycle cost savings and the amount of commonality, while meeting the goals and needs of the envisioned customers’ segments. A simulated annealing based algorithm that can solve problems heuristically is then used to help the decision maker in selecting a scope for the product platform, by performing tradeoff analysis of the commonality and cost savings objectives.ResultsIn a case study, PPSMS helped in identifying 5 non-dominated solutions considered to be of highest preference for decision making, taking into account both cost savings and commonality objectives. A quantitative and qualitative analysis indicated that human experts perceived value in adopting the method in practice, and that it was effective in identifying appropriate product platform scope.     

基于分级置信度传播的立体匹配新方法

针对当前全局立体匹配算法效率低下以及在遮挡区域难以准确匹配的问题,提出了一种高效的基于分层置信度传播的立体匹配新方法。该方法首先采用高效局部匹配获得初 始匹配代价,并根据初始匹配的结果检测遮挡和误匹配像素;其次,使用平面化估计的结果对初始代价进行了修正,改善了遮挡区域的匹配效果;最后使用改进的分层置信度传播 快速估计最小化能量,降低了低纹理区域的误匹配,提高了整体的平滑度。实验结果表明,该方法在精度和速度上具有较高的性能。     

A novel approach for combination of individual and group decisions based on fuzzy best-worst method

The process of decision-making in an enterprise may either keep the business on track or derail it. Thus, a senior decision maker often use a group of experts as the supportive team to ensure appropriate decisions. The experts often have different expertise level regarding their knowledge, talent, proficiency, and experience. In this study, we first extend the best-worst method based on the linguistic preferences of decision-makers about importance of attributes. These preferences are converted into triangular fuzzy numbers to be utilized in the linear programming model. That is, in contrast with the original best-worst method in which the preferences towards the attributes are crisp, fuzzy preferences are considered in the proposed method to reflect the imprecise comments of experts. Second, we propose a novel group decision making approach based on the fuzzy best-worst method to combine the opinion of senior decision-maker and the opinions of the experts. Indeed, our model helps the senior decision-maker to make a significant trade-off between democratic and autocratic decision-making styles. From sensitivity analyses on two numerical examples, we show that, when there is conflict between senior decision-maker and group of decision-makers, the consistency of group decision-making (democracy) will increase as it tends to individual decision-making (autocracy).     

Supplier selection using a clustering method based on a new distance for interval type-2 fuzzy sets: A case study

Supplier selection is a decision-making process to identify and evaluate suppliers for making contracts. Here, we use interval type-2 fuzzy values to show the decision makers’ preferences and also introduce a new formula to compute the distance between two interval type-2 fuzzy sets. The performance of the proposed distance formula in comparison with the normalized Hamming, normalized Hamming based on the Hausdorff metric, normalized Euclidean and the signed distances is evaluated. The results show that the signed distance has the same trend as our method, but the other three methods are not appropriate for interval type-2 fuzzy sets. Using this approach, we propose a hierarchical clustering-based method to solve a supplier selection problem and find the proximity of the suppliers. To illustrate the applicability of the proposed method, first a case study of supplier selection problem with 8 criteria and 8 suppliers are illustrated and next, an example taken from the literature is worked through. Then, to test the hierarchical clustering-based method and compare with the obtained results by two other methods, a comparative study using experimental analysis is designed. The results show that while the proposed hierarchical clustering algorithm provides acceptable results, it is also conveniently appropriate for using interval type-2 fuzzy sets and obtaining proximity of suppliers.     

基于灰色理论的小样本振荡序列区间预测建模方法

传统单变量灰色预测模型的指数结构形式制约了其对小样本振荡序列的模拟与预测能力, 对此, 通过包络线将振荡序列拓展为具有明确上界与下界的区间灰数序列, 还原影响因素不确定性条件下振荡序列的区间灰数形式; 在此基础上, 利用区间灰数建模方法实现对振荡序列取值范围的模拟与预测. 应用该方法较好地模拟了具有振荡特征的重庆市空气质量指数(AQI) 的变化规律, 所得研究成果为小样本振荡序列的模拟与预测提供了一种新的分析方法与建模手段.

     

基于LDPC码结构的盲信道噪声方差估计方法

在LDPC码的迭代软判决译码算法中需要利用信道的噪声方差,通过对二元LDPC码、采用BPSK调制的盲信道噪声方差估计方法的分析,提出了在AWGN信道条件下,采用QPSK调制的基于多元LDPC码结构的盲信道噪声方差估计算法,将估计的结果应用到多元LDPC码的译码算法中。仿真结果显示,该算法可以有效地提高信道利用率,在没有增加额外开销的同时能够得到比较准确的信噪比估计。     

一种基于FastICA的波达方向估计新方法

独立分量分析是一种新颖的盲源分离技术，该方法作为目前信号处理领域的一项新技术，具有非常重要的理论意义和实用价值，已广泛应用于通讯、雷达信号处理、生物医学图像处理、模式识别等众多领域。简要介绍了独立分量分析的基本原理和算法，并提出将快速独立分量分析（FastICA）方法应用于波达方向估计（DOA），通过仿真实验和分析，可以得到DOA的一种简单估计，实验结果亦表明该算法在波达方向估计应用中的可行性和有效性。     

一种低信噪比下DSSS的载频估计方法

直接序列扩频信号具有较低的功率谱密度,信号淹没在背景噪声中,侦查难度较大。四阶累计量2-D切片理论上可以有效地抑制高斯白噪声,但是当信噪比较低时,抑制效果不是很明显。对低信噪比下直接序列扩频信号的检测和估计提出了一种改进思路：在常规四阶累积量2-D切片前加设自适应干扰消噪器。此方法能改善白噪声背景下信号的信噪比。在此思想上基于System View平台构建了仿真模型,实现了低信噪比下DSSS信号载波频率的准确检测。仿真结果验证了其有效性。     

基于模型估计的关节式月球车参数化轨迹规划*

为了在轨迹规划阶段提高月球车在三维地形中的轨迹规划精度,以被动关节式地形自适应月球车为研究对象,融合关节机器人D-H坐标建模方法构建月球车悬架运动学模型,结合数值求解方法,推导了任意崎岖三维地形中月球车姿态估计模型.在模型估计基础上利用参数化控制原理,建立了满足约束条件下被动关节式月球车在任意地形中的基于模型估计的一般性参数化轨迹生成模型.针对轮式月球车的非完整性特点,结合数值求解方法,推导了非线性模型的求解方法.最后利用仿真方法,以八轮摇杆摇臂关节式月球车为例,验证了崎岖地形中基于模型估计的轨迹生成方法的正确性,且可提高关节式月球车在崎岖地形中的规划精度.     

基于主导边界Radon变换的SAR目标方位角估计方法

针对仅利用主导边界估计带来的目标垂直与水平方位的模糊问题,提出一种基于主导边界Radon变换的合成孔径雷达(SAR)图像目标方位角估计方法。该方法基于分割图像中目标主导边界长度的判别准则进行解模糊,同时引入目标主导边界Radon变换的估计算法,解决了传统主导边界算法中长、短主导边界不易分离的问题。MSTAR实测数据的实验结果表明提出的算法具有良好的精确度和适应性。