Synthesis of accelerograms compatible with the Chinese GB 50011-2001 design spectrum via harmonic wavelets: artificial and historic records

A versatile approach is employed to generate artificial accelerograms which satisfy the compatibility criteria prescribed by the Chinese aseismic code provisions GB 50011-2001. In particular, a frequency dependent peak factor derived by means of appropriate Monte Carlo analyses is introduced to relate the GB 50011-2001 design spectrum to a parametrically defined evolutionary power spectrum (EPS). Special attention is given to the definition of the frequency content of the EPS in order to accommodate the mathematical form of the aforementioned design spectrum. Further, a one-to-one relationship is established between the parameter controlling the time-varying intensity of the EPS and the effective strong ground motion duration. Subsequently, an efficient auto-regressive moving-average (ARMA) filtering technique is utilized to generate ensembles of non-stationary artificial accelerograms whose average response spectrum is in a close agreement with the considered design spectrum. Furthermore, a harmonic wavelet based iterative scheme is adopted to modify these artificial signals so that a close matching of the signals’ response spectra with the GB 50011-2001 design spectrum is achieved on an individual basis. This is also done for field recorded accelerograms pertaining to the May, 2008 Wenchuan seismic event. In the process, zero-phase high-pass filtering is performed to accomplish proper baseline correction of the acquired spectrum compatible artificial and field accelerograms. Numerical results are given in a tabulated format to expedite their use in practice

The global dimension in education and education for global citizenship: genealogy and critique

Encouraged by transnational organisations, curriculum policy-makers in the UK have called for curricula in schools and higher education to include a global dimension and education for global citizenship that will prepare students for life in a global society and work in a global economy. We argue that this call is rhetorically operating as a ‘nodal point’ in policy discourse a floating signifier that different discourses attempt to cover with meaning. This rhetoric attempts to bring three educational traditions together: environmental education, development education and citizenship education. We explore this new point of arrival and departure and some of the consequences and critiques

The development of Scotland’s Curriculum for Excellence: Amnesia and Déjà Vu

Scotland’s new Curriculum for Excellence (CfE) has been widely acknowledged as the most significant educational development in a generation, with the potential to transform learning and teaching in Scottish schools. In common with recent developments elsewhere, CfE seeks to re-engage teachers with processes of curriculum development, to place learning at the heart of the curriculum and to change engrained practices of schooling. This article draws upon well-established curriculum theory (notably the work of both Lawrence Stenhouse and A.V. Kelly) to analyse the new curriculum. We argue that by neglecting to take account of such theory, the curricular offering proposed by CfE is subject to a number of significant structural contradictions which may affect the impact that it ultimately exerts on learning and teaching; in effect, by ignoring the lessons of the past, CfE runs the risk of undermining the potential for real change

Tree-ring based reconstructions of northern Patagonia precipitation since AD 1600

Long-term reconstructions (400 years) of seasonal and annual precipitation variations were developed for northern Patagonia east of the Andes using a new set of 16 tree ring-width chronologies from Austrocedrus chilensis (D.Don) Endl. Reconstructions, which capture between 41 and 50% of the precipitation variance, show that the twentieth century contains the most extreme long periods of wetness and dryness in the past 400 years. Since about AD 1910, the reconstructions are also characterized by an increase in interannual variability and one of the highest rates of extreme events within the last 400 years. A prominent oscillation on the order of 2-2.1 years in length has been identified in the reconstructions using spectral analysis. Quasi-Biennial Oscillations have been shown to be very marked in some circulation indices of the Southern Hemisphere. Although significant oscillations within the preferred frequency domain of El Nino-Southern Oscillation (ENSO) are present in the reconstructions, no clear trod consistent responses to ENSO have been observed. Correlations of reconstructions with mean sea-level pressure around South America for the interval AD 1912-1984, reveal the influence of subtropical and high-latitude features of the atmospheric circulation on precipitation variations in northern Patagonia. Droughts result from an intensification of the subtropical Pacific anticyclone off the Chilean coast and the deepness of the circum-Antarctic trough over the South Orkney-Antarctic Peninsula sector. Mean sea-level pressure reconstructions for the South Atlantic sector of the Southern Oceans were used to evaluate the temporal stability of the relationships between northern Patagonia precipitation and high-latitude climatic variations since AD 1750. The influence of high-latitude circulation on precipitation appears to be more significant during the twentieth century, which in turn may respond to an intensification of wavenumbers 3 on the mean planetary wave structure over the Southern Hemisphere. Recent increase of precipitation variability in northern Patagonia may reflect stronger interactions between middle- and high-latitude atmospheric circulation in the Southern Hemisphere during the twentieth century