Towards a Model Transformation Intent Catalog

in Proceedings of the First Workshop on Analysis of Model Transformations (2012)

Comment assurer l’évaluation diagnostique des compétences scolaires ? - Table ronde

Scientific Conference (2012)

Updating the Precise Gravity Network at the BIPM

in Geodesy for Planet Earth (2012)

Constitutional amendment in Luxembourg Chapter 12

in Contiades, Xenophon (Ed.) Engineering Constitutional Change. A Comparative Perspective on Europe, Canada and the USA, 478 p. (2012)

Optimal Sensor Placement for Leakage Detection and Isolation in Water Distribution Networks

in Fault Detection, Supervision and Safety of Technical Processes, Volume# 8 | Part# 1 (2012)

In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural ... [more ▼]

In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural models and thus it is suitable to handle non-linear and large scale systems. A drawback of this technique arises when costs are assigned uniformly. A main contribution of this paper is the proposal of an iterative methodology that focuses on identifying essential sensors which ultimately leads to an improvement of the optimal search efficiency. The algorithm presented in this work is successfully applied to a District Metered Area (DMA) in the Barcelona water distribution network. [less ▲]

Strategies to mitigate aliasing of loading signals while estimating GPS frame parameters

in Journal of Geodesy (2012), 86(1), 1-14

Although GNSS techniques are theoretically sensitive to the Earth center of mass, it is often preferable to remove intrinsic origin and scale information from the estimated station positions since they ... [more ▼]

Although GNSS techniques are theoretically sensitive to the Earth center of mass, it is often preferable to remove intrinsic origin and scale information from the estimated station positions since they are known to be affected by systematic errors. This is usually done by estimating the parameters of a linearized similarity transformation which relates the quasi-instantaneous frames to a long-term frame such as the International Terrestrial Reference Frame (ITRF). It is well known that non-linear station motions can partially alias into these parameters. We discuss in this paper some procedures that may allow reducing these aliasing effects in the case of the GPS techniques. The options include the use of well-distributed sub-networks for the frame transformation estimation, the use of site loading corrections, a modification of the stochastic model by downweighting heights, or the joint estimation of the low degrees of the deformation field. We confirm that the standard approach consisting of estimating the transformation over the whole network is particularly harmful for the loading signals if the network is not well distributed. Downweighting the height component, using a uniform sub-network, or estimating the deformation field perform similarly in drastically reducing the amplitude of the aliasing effect. The application of these methods to reprocessed GPS terrestrial frames permits an assessment of the level of agreement between GPS and our loading model, which is found to be about 1.5 mm WRMS in height and 0.8 mm WRMS in the horizontal at the annual frequency. Aliased loading signals are not the main source of discrepancies between loading displacement models and GPS position time series. [less ▲]

Europäisierung der Städtepolitik? Das Beispiel 'CIPU' in Luxemburg

in Europa Regional (2012), 10(18.2010), 38-47

Europeanization of Urban Policy? The example of 'CIPU' in Luxemburg For many years, the ‘Europeanization’ of urban policy and urban development has been vividly discussed as a result of European and ... [more ▼]

Europeanization of Urban Policy? The example of 'CIPU' in Luxemburg For many years, the ‘Europeanization’ of urban policy and urban development has been vividly discussed as a result of European and intergovernmental initiatives in this particular policy field. Based on Radaelli’s concept of Europeanization, this paper examines the development of a European urban policy as well as its increasing importance and impact on the Luxembourgish urban policy with the example of the National Information Cell for Urban Policy (Cellule nationale d’Information pour la Politique Urbaine – CIPU), established in 2008. The empirical evidence shows that the competent Luxembourgish institutions have recognized that European urban policy is of vital importance to the sustainable and polycentric development of Luxembourg. Due to the establishment of CIPU, greater account is taken of the potential of cities and the current challenges that they are facing. This is achieved, among other things, by means of better coordination and an improved provision of information for Luxembourgish stakeholders, a more efficient concentration of means and measures as well as extended opportunities for local stakeholders to influence European policy-making. [less ▲]

Nontidal ocean loading: amplitudes and potential effects in GPS height time series

in Journal of Geodesy (2012), 86(11), 1043-1057

Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean’s internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a ... [more ▼]

Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean’s internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a change in the integrated atmospheric mass over the ocean areas. The only previous global analysis investigating the magnitude of OBP surface displacements used older OBP data sets (van Dam et al. in J Geophys Res 129:507–517, 1997). Since then significant improvements in meteorological forcing models used to predict OBP have been made, augmented by observations from satellite altimetry and expendable bathythermograph profiles. Using more recent OBP estimates from the Estimating the Circulation and Climate of the Ocean (ECCO) project, we reassess the amplitude of the predicted effect of OBP on the height coordinate time series from a global distribution of GPS stations. OBP-predicted loading effects display an RMS scatter in the height of between 0.2 and 3.7 mm, larger than previously reported but still much smaller (by a factor of 2) than the scatter observed due to atmospheric pressure loading. Given the improvement in GPS hardware and data analysis techniques, the OBP signal is similar to the precision of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using the MIT reprocessed solution, mi1. When we compare the predicted OBP height time series with mi1, we find that the scatter is reduced over all stations by 0.1 mm on average with reductions as high as 0.7 mm at some stations. More importantly we are able to reduce the scatter on 65 % of the stations investigated. The annual component of the OBP signal is responsible for 80 % of the reduction in scatter on average.We find that stations located close to semi-enclosed bays or seas are affected by OBP loading to a greater extent than other stations. [less ▲]

Probing Quantum Confinement within Single Core–Multishell Nanowires

in Nano Letters (2012), 12(11), 5829-5834

Theoretically core–multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier ... [more ▼]

Theoretically core–multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier localization phenomena at the hexagon corners by combining synchrotron excited optical luminescence with simultaneous X-ray fluorescence spectroscopy. Applied to single coaxial n-GaN/InGaN multiquantum-well/p-GaN nanowires, our experiment narrows the gap between optical microscopy and high-resolution X-ray imaging and calls for further studies on the underlying mechanisms of optoelectronic nanodevices. [less ▲]

Hierarchies of local monotonicities and lattice derivatives for Boolean and pseudo-Boolean functions

in Miller, D. Michael; Gaudet, Vincent C. (Eds.) 42nd IEEE International Symposium on Multiple-Valued Logic, ISMVL 2012, Victoria, BC, Canada, May 14-16, 2012 (2012)

In this paper we report recent results in [1] concerning local versions of monotonicity for Boolean and pseudo-Boolean functions: say that a pseudo-Boolean (Boolean) function is p-locally monotone if each ... [more ▼]

In this paper we report recent results in [1] concerning local versions of monotonicity for Boolean and pseudo-Boolean functions: say that a pseudo-Boolean (Boolean) function is p-locally monotone if each of its partial derivatives keeps the same sign on tuples which differ on less than p positions. As it turns out, this parameterized notion provides a hierarchy of monotonicities for pseudo-Boolean (Boolean) functions. Local monotonicities are tightly related to lattice counterparts of classical partial derivatives via the notion of permutable derivatives. More precisely, p-locally monotone functions have p-permutable lattice derivatives and, in the case of symmetric functions, these two notions coincide. We provide further results relating these two notions, and present a classification of p-locally monotone functions, as well as of functions having p-permutable derivatives, in terms of certain forbidden “sections”, i.e., functions which can be obtained by substituting variables for constants. This description is made explicit in the special case when p=2. [less ▲]