Stabilizability and Detectability of Singularly Perturbed Linear Time-Invariant Systems with Delays in State and Control

A singularly perturbed linear time-invariant system with delays in state and control variables is considered. Connection between properties of open-loop stabilizability (detectability) of the reduced-order and boundary-layer systems, associated with the original system, and such properties of the original system itself are analyzed.     

超声衍射传播时间法与射线照相法对缺陷检出能力的比较

介绍国外焊缝用超声衍射传播时间法(TOFD)与射线照相法在缺陷检出能力和定量精度方面的比较,最后得出,锅炉、压力容器焊缝(板厚>12.7mm)可用超声TOFD法取代RT检测的结论。     

Working towards a test for screening visual skills in a complex visual environment

We developed a test for screening visual skills under similar conditions as at workplace. The test was administered to 207 participants, recruited in the working population. Six-digit numbers were super-imposed on a video of a drive and presented for 300 ms in the central visual field and in the periphery. Participants reported whether or not the integer ‘3’ was included in the numbers. Normative data for the test were computed using 150 data sets of participants reporting not to take drugs and with an age ranging between 15 y and 67 y. Participants performed better in the central visual field than in periphery. The test could successfully be completed by participants of all ages without the need of adjustment of settings. Comparison of 46 data sets recorded in participants taking drugs (30 y – 68 y) with age matched participants not taking drugs demonstrates an additional potential application of the test.

Practitioner Summary: Developed test delivers comparative estimates of visual skills within short time and appears as valuable and cheap complementation to current testing procedures in industrial practice. The test can be used in a preventive and in educative manner to monitor effects of factors like fatigue, sleep deprivation or drug consumption.     

能力验证提升实验室检测水平的实证研究

为分析能力验证对实验室检测能力提升的促进方式,定量能力验证对实验室检测能力的提升效能,分析了305家实验室2010-2015年间参加柴油检测能力验证的3 133个评价结果和能力评价统计量|Z|值的变动趋势。研究表明,随参加能力验证次数增加,实验室检测能力显著提高,但单次能力验证不能有效保证持续检测能力。通过3轮能力验证,实验室能够基本消除检测过程中的关键错误。对于不同检测项目间能力验证的相互作用研究表明,通过参加某一项目的能力验证,实验室提高了其他项目的技术水平,表明能力验证能够促进实验室整体能力提升,而非局限于单一的检测项目。能力验证对实验室检测能力的作用方式可分为2种,一种通过消除检测技术的关键错误,直接提升能力验证参加项目的技术水平;另一种通过提升实验室整体管理能力,间接提升其他检测项目的技术水平。     

新息图拓扑可观测性及不良数据可辨识性分析

新息图状态估计在拓扑结构获取和不良数据辨识方面与一般状态估计差异较大。文中研究了新息图状态估计拓扑结构可观测性、量测数据的相关性、不良数据的可检测性和可辨识性问题。由获得连支推算新息的必要条件确定拓扑结构可观测性;利用新息差向量的表现特征分析不良数据可检测性和可辨识性,最后给出了较优的辨识连支不良数据的顺序。对该算法的分析及IEEE30节点系统算例表明,新息图状态估计中不良数据可辨识性可进行定性分析,其辨识不正常事件的能力强,量测冗余度要求较低。     

Observer and observer-based H∞ control of generalized Hamiltonian systems

This paper deals with observer design for generalized Hamiltonian systems and its applications. First, by using the systems' structural properties, a new observer design method called Augment Plus Feedback is provided and two kinds of observers are obtained: non-adaptive and adaptive ones. Then, based on the obtained observer, H∞ control design is investigated for generalized Hamiltonian systems, and an observer-based control design is proposed. Finally, as an application to power systems, an observer and an observer-based H∞ control law are designed for single-machine infinite-bus systems.Simulations show that both the observer and controller obtained in this paper work very well.     

控制系统状态故障的可检测性研究

从控制系统的结构出发 ,对线性系统状态故障的可检测性进行了讨论 ,提出并证明了线性能观系统的状态故障是可检测的结论     

An argument-principle-based framework for structural and spectral characteristics in linear dynamical systems

By means of the argument principle in complex analysis, the paper proposes a novel complex geometric framework about structural features in terms of controllability/observability and stability/stabilisability, and spectral ones in terms of bounded/positive realness for transfer functions in linear dynamical systems. The proposed criteria render alternative complex/frequency-domain interpretations about the structural and spectral essentials. Moreover, the criteria are implementable graphically with locus plotting, independent of singularities distribution, locus orientation specification, singularity-related locus encirclement counting and prior frequency sweeping; the criteria are also utilisable numerically via complex argument increment integration without locus plotting, independent of iterative algorithms. In either ways, the criteria are numerically tractable and opt for robustness analysis and synthesis. Numerical examples are included to illustrate the main results.     

Influence of some practical factors on background extrapolation in EELS quantification

The detectability of a minor element with EELS in a STEM is of great interest. This paper first describes errors resulting from a conventional background extrapolation scheme and other faults in the collected spectra which in effect greatly reduce the seemingly good signal to noise ratio of a spectrum and therefore impose much more stringent statistical counting requirement on spectra if a small amount of element is to be quantified with good accuracy. Secondly, the systematic variation of the index r of the power law background fitting curve of an ionizatoin edge tail is discussed. Its effect on the detectability of a minor element is analysed. It puts a lower limit on the detectability of an element, however many counts are accumulated. Also a scheme is proposed of some non-conventional linear least squares fits by which one might suffer from less quantification error due to background extrapolation and achieve lower detectability of a minor element.