Residual‐based a posteriori estimators for the potential formulations of electrostatic and time‐harmonic eddy current problems with voltage or current excitation

In this paper, we consider some potential formulations of electrostatic as well as time‐harmonic eddy current problems with voltage or current excitation sources. The well‐posedness of each formulation is first established. Then, the reliability of the corresponding residual‐based a posteriori estimators is derived in the context of the finite element method approximation. Finally, the implementation in an industrial code is performed, and the obtained theoretical results are illustrated on an academic and on an industrial benchmark. Copyright © 2015 John Wiley & Sons, Ltd.     

A Copula Approach in the Point Estimate Method for Reliability Engineering

In order to arrive at realistic results in statistical analysis, it is often advisable to consider involved uncertainties as random variables. An important aspect in this context is the evaluation of the importance of parameter uncertainty. Because of the complexity of computational models, the point estimate method is usually adopted as an easy‐run approach for approximating the statistical moments of a system/model in a reliability analysis. The efficiency of this method highly depends on the correlation coefficient. However, the complex nature of parameters in computational problems often exhibits a nonlinear relationship. This paper aims to develop an original and efficient point estimate method based on the copula approach for reliability engineering problems. The paper discusses the use of the copula theory in the point estimate method for computing the statistical moments of a function involving random variables. The study performs two engineering applications to demonstrate the benefits of this approach. The performance of this proposed method can significantly improve the quality of the results in using the point estimate method when a nonlinear relationship exists between the parameters. Copyright © 2015 John Wiley & Sons, Ltd.     

Goal-oriented adaptivity based on a model hierarchy of mean-field and full-field homogenization methods in linear elasticity

Homogenization methods are drawing increasing attention for simulation of heterogeneous materials like composites. For balancing the accuracy and the numerical efficiency of such strategies, we deal with both model and discretization errors of the finite element method (FEM) on a macroscale. Within a framework of goal-oriented adaptivity, we consider linear elastic heterogeneous materials, for which first-order homogenization schemes apply. A novel model hierarchy is proposed based on mean-field and full-field homogenization methods. For the former, we consider several well-established schemes like Mori-Tanaka or self-consistent as basic models, and for the latter, as superior models, unit cell problems are solved via the FEM under an a priori chosen boundary condition. For a further stage of the model hierarchy, we consider hierarchical unit cells within the frame of the FEM toward an adaptive selection of the unit cell size. By means of several numerical examples, we illustrate the effectiveness of the proposed adaptive approach.     

投标报价探讨

介绍了投标报价的过程，从施工图预算和单价分析、投标报价的确定、投标报价技巧等方面进行了论述，指出投标报价是建筑企业取得经济效益的重要组成部分。     

论建设项目全过程造价的控制与管理

根据工程项目投资建设的四个阶段，介绍了各个阶段工程造价的控制与管理技术，以保证科学有效的造价控制，使项目投资获得良好的效益和回报。     

Comparison of methods to correct the miscounting of multiple episodes of care when estimating the incidence of hospitalised injury in child motor vehicle passengers

This study evaluates the performance of different case selection criteria to account for multiple episodes of care when estimating the hospitalisation rate due to road trauma amongst children. The internally linked NSW Inpatient Statistics Collection (ISC) dataset for the period between 1st July, 2000 and 30th June, 2003 was used to identify the "single" episode of care for each hospitalised child motor vehicle passenger residing in NSW. We used two hospitalised injury definitions of a case based on (1) all-diagnoses and (2) principal diagnosis only. We then developed case selection criteria, based on (a) linkage methods only available from linked ISC datasets; (b) selected variables available in both the linked and unlinked ISC datasets, to exclude repeat episodes of care for an injury. Changes in the estimated hospitalisation rate, and sensitivity and specificity, were calculated for each selection criteria compared to the findings from linkage methods as the "gold standard". None of the correction methods for multiple episodes of care was clearly superior in terms of incidence estimation, sensitivity, and specificity concurrently. However, the correction criterion which is optimal may vary depending on different study objectives and different types of hospitalised injuries.     

多变异源过程控制与指数加权移动平均控制图的应用研究

改进休哈特控制图能够解决多变异源过程控制虚发警报错误过高的问题,但是对均值偏移的检出力过低。本文研究的目的是将指数加权移动平均(EWMA)控制图用于多变异源过程控制,提高控制图对均值偏移的检出力。通过对多个变异源的方差分析,基于对部分方差估计,给出指数加权移动平均控制图在多变异源过程控制的应用方法。通过计算指数加权移动平均控制图的平均运行长度,并与改进的休哈特控制图作比较,证明指数加权移动平均控制图在检测多变异源过程均值偏移时检出力有较大提高,应用实例的结果表明当偏移量小于1σ时,检出力能提高10倍以上。     

抗差估计定权方法及与其他方法抗差效果比较研究

在参数回归估计中,不同的权函数形式产生了不同的估计方法.文中主要介绍了利用误差分布律概率密度函数定权来进行抗差估计的一种方法.首先从理论上阐述了此种抗差方法,并通过实例同最小二乘法和几种抗差估计方法(Huber估计法、Hampel估计法、丹麦估计法)作了比较;证明了此种方法的优越性.     

Vector quantization using information theoretic concepts

The process of representing a large data set with a smaller number of vectors in the best possible way, also known as vector quantization, has been intensively studied in the recent years. Very efficient algorithms like the Kohonen self-organizing map (SOM) and the Linde Buzo Gray (LBG) algorithm have been devised. In this paper a physical approach to the problem is taken, and it is shown that by considering the processing elements as points moving in a potential field an algorithm equally efficient as the before mentioned can be derived. Unlike SOM and LBG this algorithm has a clear physical interpretation and relies on minimization of a well defined cost function. It is also shown how the potential field approach can be linked to information theory by use of the Parzen density estimator. In the light of information theory it becomes clear that minimizing the free energy of the system is in fact equivalent to minimizing a divergence measure between the distribution of the data and the distribution of the processing elements, hence, the algorithm can be seen as a density matching method.     

工程造价预算控制措施分析

在建设工程中,工程造价预算有着重要的作用,它直接影响着工程建设的社会和经济学效应。因此,加强对工程造价的控制至关重要。主要论述了建筑工程造价的构成、工程造价超预算的原因,并分析探究了能够有效控制工程造价预算的具体措施。