Stability of switched linear differential systems

We study the stability of switched systems where the dynamic modes are described by systems of higher-order linear differential equations not necessarily sharing the same state space. Concatenability of trajectories at the switching instants is specified by gluing conditions, i.e. algebraic conditions on the trajectories and their derivatives at the switching instant. We provide sufficient conditions for stability based on LMIs for systems with general gluing conditions. We also analyse the role of positive-realness in providing sufficient polynomial-algebraic conditions for stability of two-modes switched systems with special gluing conditions

Nuclear design and experiments for a space power reactor

Design and experiments with compact fast spectrum reactor for generating electric power in spac

Performing against the odds: developmental trajectories of children in the EPPSE 3 to 16 study

The Effective Pre-School, Primary and Secondary Education (EPPSE 3 to 16) research project is a large scale, longitudinal, mixed-methods research that is following the progress of 3,000 children since 1997 from the age of 3- to 16-years-old. A focus for EPPSE has been the extent to which pre-school, compulsory education and children’s home learning experiences (HLE) can reduce inequality. Earlier EPPSE found that what parents did with their children was important in terms of the children’s outcomes, not simply ‘who they were’ in terms of social class and income. Following a pilot study with disadvantaged children who were ‘succeeding against the odds’ towards the end of primary school, this study provides in-depth exploration and explanation of how risks and protective factors in the lives of children shape their learning life-courses, and why they lead to academic resilience for some but not for others

Spectroscopic study of unique line broadening and inversion in low-pressure microwave generated water plasmas

It was demonstrated that low pressure (~0.2 Torr) water vapor plasmas generated in a 10 mm inner diameter quartz tube with an Evenson microwave cavity show at least two features which are not explained by conventional plasma models. First, significant (> 0.25 nm) hydrogen Balmer_ line broadening, of constant width, up to 5 cm from the microwave coupler was recorded. Only hydrogen, and not oxygen, showed significant line broadening. This feature, observed previously in hydrogen-containing mixed gas plasmas generated with high voltage dc and rf discharges was explained by some researchers to result from acceleration of hydrogen ions near the cathode. This explanation cannot apply to the line broadening observed in the (electrodeless) microwave plasmas generated in this work, particularly at distances as great as 5 cm from the microwave coupler. Second, inversion of the line intensities of both the Lyman and Balmer series, again, at distances up to 5 cm from the coupler, were observed. The line inversion suggests the existence of a hitherto unknown source of pumping of the optical power in plasmas. Finally, it is notable that other aspects of the plasma including the OH* rotational temperature and low electron concentrations are quite typical of plasmas of this type.Comment: 27 pages, 7 figure

Development of dynamic calibration methods for POGO pressure transducers

Two dynamic pressure sources are described for the calibration of pogo pressure transducers used to measure oscillatory pressures generated in the propulsion system of the space shuttle. Rotation of a mercury-filled tube in a vertical plane at frequencies below 5 Hz generates sinusoidal pressures up to 48 kPa, peak-to-peak; vibrating the same mercury-filled tube sinusoidally in the vertical plane extends the frequency response from 5 Hz to 100 Hz at pressures up to 140 kPa, peak-to-peak. The sinusoidal pressure fluctuations can be generated by both methods in the presence of high pressures (bias) up to 55 MPa. Calibration procedures are given in detail for the use of both sources. The dynamic performance of selected transducers was evaluated using these procedures; the results of these calibrations are presented. Calibrations made with the two sources near 5 Hz agree to within 3% of each other

A dynamic pressure source for the calibration of pressure transducers

A dynamic pressure source is described for producing sinusoidally varying pressures of up to 34 kPa zero to peak, over the frequency range of approximately 50 Hz to 2 kHz. The source is intended for the dynamic calibration of pressure transducers. The transducer to be calibrated is mounted near the base of the thick walled aluminum tube forming the vessel so that the pressure sensitive element is in contact with the liquid in the tube. A section of the tube is filled with small steel balls to damp the motion of the 10-St dimethyl siloxane working fluid in order to extend the useful frquency range to higher frequencies than would be provided by an undamped system. The dynamic response of six transducers provided by the sponsor was evaluated using the pressure sources; the results of these calibrations are given

Lifelong learning and schools as community learning centres : key aspects of a national curriculum draft policy framework for Malta

The island of Malta has been engaged in policy document formulations for curriculum renewal in the country’s educational system (4-16 years of age) since 1988 when the first National Minimum Curriculum (henceforth NMC) was launched (Wain, 1991; Borg et al, 1995). In 1999 a revamped NMC (Ministry of Education, 1999) was developed following a long process of consultation involving various stages and stakeholders. It was a compromise document (Borg & Mayo, 2006) which emerged as a result of reactions to a more radical and coherent draft document produced in 1988. Both curricular documents were subject to debates and critiques (Wain, 1991; Darmanin, 1993; Borg et al, 1995; Giordmaina, 2000; Borg and Mayo, 2006). More recently a series of volumes providing guidelines, key principles and aims for a national curriculum framework (henceforth NCF) have been produced (MEEF, 2011a,b,c,d) and are currently the target of debate and the focus of reactions by various stakeholders in education including teachers who were asked to read the volumes and provide reactions in the form of answers to a set questionnaire. In this paper, I will focus on one aspect of the documents, the first of its three aims: ‘Learners who are capable of successfully developing their full potential as lifelong learners.’ It is that aspect of the framework documents that falls within the purview of the title for this special issue. The use of this notion attests to the influence of the EU’s policy communications on member states, Malta having joined the Union in 2004 (Mayo, 2007).peer-reviewe

Education and articulation: Laclau and Mouffe’s radical democracy in school

This paper outlines a theory of radical democratic education by addressing a key concept in Laclau and Mouffe’s Hegemony and Socialist Strategy: articulation. Through their concept of articulation, Laclau and Mouffe attempt to liberate Gramsci’s theory of hegemony from Marxist economism, and adapt it to a political sphere inhabited by a plurality of struggles and agents none of which is predominant. However, while for Gramsci the political process of hegemony formation has an explicit educational dimension, Laclau and Mouffe ignore this dimension altogether. My discussion starts with elaborating the concept of articulation and analysing it in terms of three dimensions: performance, connection and transformation. I then address the role of education in Gramsci’s politics, in which the figure of the intellectual is central, and argue that radical democratic education requires renouncing that figure. In the final section, I offer a theory of such education, in which both teacher and students articulate their political differences and identities