Robust observer-based fault estimation and accommodation of discrete-time piecewise linear systems

In this paper a new integrated observer-based fault estimation and accommodation strategy for discrete-time piecewise linear (PWL) systems subject to actuator faults is proposed. A robust estimator is designed to simultaneously estimate the state of the system and the actuator fault. Then, the estimate of fault is used to compensate for the effect of the fault. By using the estimate of fault and the states, a fault tolerant controller using a PWL state feedback is designed. The observer-based fault-tolerant controller is obtained by the interconnection of the estimator and the state feedback controller. We show that separate design of the state feedback and the estimator results in the stability of the overall closed-loop system. In addition, the input-to-state stability (ISS) gain for the closed-loop system is obtained and a procedure for minimizing it is given. All of the design conditions are formulated in terms of linear matrix inequalities (LMI) which can be solved efficiently. Also, performance of the estimator and the state feedback controller are minimized by solving convex optimization problems. The efficiency of the method is demonstrated by means of a numerical example.     

Not Meta Just Data: Redefining Content and Metadata in Archival Theory and Practice1

How we imagine records affects what we acquire and how we manage it. I take up the call from Arjun Appadurai to view archives as deliberate creations, and from Hugh Taylor to use imagination as a means of creative engagement with archival theory. I explore how we can reimagine archival work, mandates, and records by eschewing divisions of content and metadata, acknowledging items and aggregations to be interchangeable concepts, and integrating data about use into archival data management.     

Book Review

This book is a good example of the contribution a clear conceptual analysis can make to highlighting and clarifying problematic thinking about real issues in education. In the literature there are different claims of varying strength and plausibility which require very careful sorting. David Carr demonstrates such careful sorting in the difficult field of ethics and maps some paths for fruitful thinking about professionalism in teaching. 'The distinctions of Peters and others between education and teaching, theory and practice, and intrinsic and instrumental value, stand in need of more careful mapping and refinement' which could enable us to steer clear of 'educationally pernicious conclusions' (p. 179). Carr succeeds in doing just this.     

A novel on-chip three-dimensional micromachined calorimeter with fully enclosed and suspended thin-film chamber for thermal characterization of liquid samples

A microfabricated calorimeter (μ-calorimeter) with an enclosed reaction chamber is presented. The 3D micromachined reaction chamber is capable of analyzing liquid samples with volume of 200 nl. The thin film low-stress silicon nitride membrane is used to reduce thermal mass of the calorimeter and increase the sensitivity of system. The μ-calorimeter has been designed to perform DC and AC calorimetry, thermal wave analysis, and differential scanning calorimetry. The μ-calorimeter fabricated with an integrated heater and a temperature sensor on opposite sides of the reaction chamber allows to perform thermal diffusivity and specific heat measurements on liquid samples with same device. Measurement results for diffusivity and heat capacitance using time delay method and thermal wave analysis are presented.     

Continuous classification: capturing dynamic relationships among information resources

Records classification within electronic records management systems often is constrained by rules derived from paper-era recordkeeping, particularly the rule that one record can have only one file code??a rule that was developed to enable the management of records in aggregate. This paper calls for a transformation of recordkeeping and archival practice through an expanded definition of records classification and through item-level management of electronic records.     

Book Review

This book is a good example of the contribution a clear conceptual analysis can make to highlighting and clarifying problematic thinking about real issues in education. In the literature there are different claims of varying strength and plausibility which require very careful sorting. David Carr demonstrates such careful sorting in the difficult field of ethics and maps some paths for fruitful thinking about professionalism in teaching. ‘The distinctions of Peters and others between education and teaching, theory and practice, and intrinsic and instrumental value, stand in need of more careful mapping and refinement’ which could enable us to steer clear of ‘educationally pernicious conclusions’ (p. 179). Carr succeeds in doing just this.     

Green Doesn't Always Mean ‘Go’: possible tensions in the desirability and implementation of environmental education

Although there are different interpretations of environmental education, they all share two assumptions, i.e. that environmental education is a desirable objective, and that it needs to be implemented as widely and as urgently as possible. This paper argues that these two assumptions cannot be taken for granted in South Africa, with its particular history of apartheid and developmental needs. I examine four possible responses to the dominant Western/Northern interpretation of environmental education and argue that in South Africa the fourth response may prove to be the most fruitful one to pursue, for it moves beyond tensions generated by race and class issues.     

‘Embodied knowing’: exploring the founding of the Melbourne Rudolf Steiner school in 1970s Victoria,Australia

ABSTRACT

Education in Victoria, Australia not only underwent significant change in the 1970s, but was witness to a widespread educational reform project. Whilst exploration of the more widespread alternatives has been of some interest, the smaller progressive traditions that emerged in some ways ‘alongside’ the broader reforms have rarely been examined in any detail. This article explores the founding of the Melbourne Rudolf Steiner School (MRSS) in the 1970s, the first of its kind in Victoria, and the third such school nationally. Analysis is based primarily on interviews with educators directly involved. L.A. Reid’s notion of education as an ‘aesthetic’ object is drawn on to examine the collective experiences of the founders of the MRSS, and the particular expression they gave to Steiner’s educational ideas.