一种求解网损因子的新方法

从耗散功率转归理论所提出的支路功率损耗公式出发,分别针对考虑与不考虑节点注入无功功率对有功功率损耗的影响两种情况下,推导出了用于求解系统总的有功损耗、各节点应当分摊到的有功损耗、节点网损因子的新公式。与传统求解方法相比,该方法完全依靠支路的参数,物理含义清晰,更易于计算。     

基于粗糙集理论的不完备数据分析方法的混合信息系统填补算法

为了提高基于粗糙集理论的不完备数据分析方法（ROUSTIDA）在实际应用中对包含离散型（如整型、字符串型、枚举型）、连续型（如浮点数表达）、缺失型属性的混合信息系统（HIS）数据的填补能力,提出了一种基于粗糙集理论的混合信息系统缺失值填补方法（RSHISMIA）。首先,根据决策属性等价类划分思想并按照决策属性对混合信息系统HIS进行划分,解决了填补后可能出现的决策规则冲突问题;其次,定义混合距离矩阵来合理量化对象间的相似性,从而筛选出具有填补能力的样本并克服ROUSTIDA无法处理连续性属性的缺点;然后,结合近邻思想解决了ROUSTIDA在无差别对象属性值发生冲突情况下无法对相同属性缺失数据进行填补的问题。最后,使用10个UCI标准数据集进行实验,将所提出的方法与ROUSTIDA、K近邻填补（KNNI）算法、随机森林填补（RFI）算法和矩阵分解（MF）等几种经典算法进行了比较。实验结果表明,与ROUSTIDA相比,所提方法在查全率上平均高出81%,在查准率上提升了5%~53%,且其归一化均方根误差（NRMSE）最多减小了0.12。此外,所提方法的分类准确率与ROUSTIDA相比平均提升了7%,且优于KNNI、RFI及MF等填补算法。     

Imputation techniques for multivariate missingness in software measurement data

The problem of missing values in software measurement data used in empirical analysis has led to the proposal of numerous potential solutions. Imputation procedures, for example, have been proposed to ‘fill-in’ the missing values with plausible alternatives. We present a comprehensive study of imputation techniques using real-world software measurement datasets. Two different datasets with dramatically different properties were utilized in this study, with the injection of missing values according to three different missingness mechanisms (MCAR, MAR, and NI). We consider the occurrence of missing values in multiple attributes, and compare three procedures, Bayesian multiple imputation, k Nearest Neighbor imputation, and Mean imputation. We also examine the relationship between noise in the dataset and the performance of the imputation techniques, which has not been addressed previously. Our comprehensive experiments demonstrate conclusively that Bayesian multiple imputation is an extremely effective imputation technique.

工业过程数据中缺失值处理方法的研究

针对工业生产中过程数据的缺失问题,首次提出了运用多重填补方法处理工业过程的缺失数据.阐述了常用的缺失数据处理方法,指出各方法的优缺点.在此基础上,通过建立回归模型,针对多变量工业数据中缺失值较少和较多时的两种情况,分别用删除含缺失值的个案,简单填补和多重填补(MI)3种方法对数据进行处理,利用处理后的新数据集进行数据挖掘,预测目标变量的值,并对预测结果进行分析比较.实验结果表明,多重填补方法的处理效果最好,为工业数据的缺失值处理提供了有用的策略.     

Short communication: The role of genotypes from animals without phenotypes in single-step genomic evaluations

In a 2-step genomic system, genotypes of animals without phenotypes do not influence genomic prediction of other animals, but that might not be the case in single-step systems. We investigated the effects of including genotypes from culled bulls on the reliability of genomic predictions from single-step evaluations. Four scenarios with a constant amount of phenotypic information and increasing numbers of genotypes from culled bulls were simulated and compared with respect to prediction reliability. With increasing numbers of genotyped culled bulls, there was a corresponding increase in prediction reliability. For instance, in our simulation scenario the reliability for selection candidates was twice as large when all culled bulls from the last 4 generations were included in the analysis. Single-step evaluations imply the imputation of all nongenotyped animals in the pedigree. We showed that this imputation was increasingly more accurate as increasingly more genotypic information from the culled bulls was taken into account. This resulted in higher prediction reliabilities. The extent of the benefit from including genotypes from culled bulls might be more relevant for small populations with low levels of reliabilities.     

Design and evaluation of a decision support system for pain management based on data imputation and statistical models

The self-reporting of pain complaints is considered the most accurate pain assessment method and represents a valuable source of data to computerised clinical decision support systems (CCDSS) for pain management. However, the subjectivity and variability of pain conditions, combined with missing data, are constraints on the usefulness and accuracy of CCDSS. Based on data imputation principles, together with several mathematical models, this paper presents a CCDSS, the Patient Oriented Method of Pain Evaluation System (POMPES), that produces tailored alarms, reports, and clinical guidance based on collected patient-reported data. This system was tested using clinical data collected during a six-week randomised controlled trial involving thirty-two volunteers recruited from an ambulatory surgery department. The decisions resulting from the POMPES were fully accurate when compared with clinical advice, which proves the ability of the system to cope with missing data and detect either stability or changes in the self-reporting of pain.     

Moment adjusted imputation for multivariate measurement error data with applications to logistic regression

In clinical studies, covariates are often measured with error due to biological fluctuations, device error and other sources. Summary statistics and regression models that are based on mis-measured data will differ from the corresponding analysis based on the “true” covariate. Statistical analysis can be adjusted for measurement error, however various methods exhibit a tradeoff between convenience and performance. Moment Adjusted Imputation (MAI) is a measurement error in a scalar latent variable that is easy to implement and performs well in a variety of settings. In practice, multiple covariates may be similarly influenced by biological fluctuations, inducing correlated, multivariate measurement error. The extension of MAI to the setting of multivariate latent variables involves unique challenges. Alternative strategies are described, including a computationally feasible option that is shown to perform well.     

一种新型2-HRR并联机构及其数控系统实现

提出了一种新型的2-HRR构型的两杆两自由度并联平动机构,其具有运动建模简单、正反解计算容易、作业空间大、结构简单和易于控制等独特的优点.本论文对该并联实验平台进行了运动学分析,并结合其结构特点开发了一种开放式、模块化的数控系统,该数控系统是以“PC机 多轴运动控制器”为硬件平台,以“VisualC ”为软件平台构建的,这种构建方式可以实现系统“积木式”的集成.在此基础上,制作了2-HRR构型并联实验平台.通过联机调试,实现了正确的加工轨迹,验证了本文机构分析的正确性和数控系统的可行性.     

A Bayesian MCMC approach to survival analysis with doubly-censored data

Doubly-censored data refers to time to event data for which both the originating and failure times are censored. In studies involving AIDS incubation time or survival after dementia onset, for example, data are frequently doubly-censored because the date of the originating event is interval-censored and the date of the failure event usually is right-censored. The primary interest is in the distribution of elapsed times between the originating and failure events and its relationship to exposures and risk factors. The estimating equation approach [Sun et al. (1999). Regression analysis of doubly censored failure time data with applications to AIDS studies. Biometrics 55, 909-914] and its extensions assume the same distribution of originating event times for all subjects. This paper demonstrates the importance of utilizing additional covariates to impute originating event times, i.e., more accurate estimation of originating event times may lead to less biased parameter estimates for elapsed time. The Bayesian MCMC method is shown to be a suitable approach for analyzing doubly-censored data and allows a rich class of survival models. The performance of the proposed estimation method is compared to that of other conventional methods through simulations. Two examples, an AIDS cohort study and a population-based dementia study, are used for illustration. Sample code is shown in Appendix A and Appendix B.