3-D GPR survey with a modular system: reducing positioning inaccuracies and linear noise

Recently, the use of ground-penetrating radar (GPR) arrays with a large number of antenna elements in a fixed configuration has become more common. The investment needed for these systems is significant. Although gradually expandable modular systems, consisting of antennas which can be used independently, do not match the fast acquisition of detailed datasets by means of multi-channel arrays, they can help finding a compromise between increased acquisition speed and (limited) resources. In modular systems, the separation between transmitter-receiver pairs is often larger than the sampling distance prescribed by the Nyquist theorem. As a consequence, additional profiles have to be recorded in between, which requires a high positioning precision. As a completely identical response for the different antennas in an array is difficult to achieve, stripes can occur in the horizontal slices, especially when ringing occurs. This complicates the interpretation of features in the direction of the survey lines. In this paper, a three-dimensional frequency-wavenumber filter is proposed, consisting in a combination of a circular filter and a fan filter. The application of this filter to GPR data collected at the Roman town Mariana (Corsica, France) showed a reduction of the stripe patterns, allowing a more reliable characterization of subtle archaeological structures

Computational design of artificial organs

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On the Core of an Economy with Multilateral and Multidimensional Environmental Externalities

For simple economic models of transfrontier pollution, Chander and Tulkens (1995) and (1997) have offered a formula for transfers to sustain international cooperation on a voluntary basis and which deter coalitional free-riding under some reasonable behaviours of countries not in the coalition. Their scheme rests on the assumption that pollution is a scalar. Relaxing this assumption, interesting interactions among pollutations arise that call for a new formula. In this paper we extend Chander and Tulkens formula for this more realistic multidimensional context, and thereby enhance the practical and theoretical relevance of their seminal analysis.international pollutions, Nash equilibrium, partial agreement Nash equilibrium, international transfers

Head Coverings in the Courtroom: A Question of Respect for the Judge or of Judicial Tolerance?

The Human Rights Centre at Ghent University (the HRC) first initiated the present research while preparing an amicus curiae brief in the Lachiri v. Belgium case before the European Court of Human Rights (ECtHR). The applicant in Lachiri, who was a civil party in legal proceedings concerning the murder of her brother, was denied access to a Brussels courtroom after refusing to remove her Islamic headscarf . Ms. Lachiri’s admission was refused in reliance on Article 759 of the Belgian Judicial Code (Gerechtelijk Wetboek/ Code Judiciaire), which provides that “[t]he audience will attend the sessions with their heads uncovered, respectfully and silently; whatever the judge commands for the maintenance of order will be punctually and immediately executed.” In its third-party intervention, the HRC sought to supply the ECtHR with additional information concerning three points: the debate on the wearing of Islamic headscarves in Belgium, the history, object and purpose of Article 759 of the Belgian Judicial Code, and the scope of the State margin of appreciation in prohibiting religious items of clothing

Modelling of priority pollutants releases from urban areas

In the framework of the EU project ScorePP (Source Control Options for Reducing Emissions of Priority Pollutants), dynamic PPs (priority pollutants) fate models are being developed to assess appropriate strategies for limiting the release of PPs from urban sources and for treating PPs on a variety of spatial scales. Different possible sources of PP releases were mapped and both their release pattern and their loads were quantified as detailed as possible. This paper focuses on the link between the gathered PP sources data and the dynamic models of the urban environment. This link consists of: (1) a method for the quantitative and structured storage of temporal emission pattern information, (2) the coupling of GIS-based spatial emission source data with temporal emission pattern information and (3) the generation of PP release time series to feed the dynamic sewer catchment model. Steps 2 and 3 were included as the main features of a dedicated software tool. Finally, this paper also illustrates the method’s applicability to generate model input timeseries for generic pollutants (N, P and COD/BOD) in addition to priority pollutants

Robust bootstrap procedures for the chain-ladder method

Insurers are faced with the challenge of estimating the future reserves needed to handle historic and outstanding claims that are not fully settled. A well-known and widely used technique is the chain-ladder method, which is a deterministic algorithm. To include a stochastic component one may apply generalized linear models to the run-off triangles based on past claims data. Analytical expressions for the standard deviation of the resulting reserve estimates are typically difficult to derive. A popular alternative approach to obtain inference is to use the bootstrap technique. However, the standard procedures are very sensitive to the possible presence of outliers. These atypical observations, deviating from the pattern of the majority of the data, may both inflate or deflate traditional reserve estimates and corresponding inference such as their standard errors. Even when paired with a robust chain-ladder method, classical bootstrap inference may break down. Therefore, we discuss and implement several robust bootstrap procedures in the claims reserving framework and we investigate and compare their performance on both simulated and real data. We also illustrate their use for obtaining the distribution of one year risk measures

Tax interaction dynamics among Belgian municipalities, 1984-1997

The purpose of this paper is to test econometrically the existence of fiscal interactions between Belgian municipalities. At the time of writing, the motivation was to provide scientific support to the lively debate on fiscal competition that took place among Belgian politicians in the late nineties. Two types of taxes are considered, for which Belgian municipalities have the decision power as to rates : the “centimes additionnels” on the personal income tax and the “précompte immobilier” which is a property tax. A dynamic adjustment model is specified and estimated using panel data for 598 municipalities over 15 years. The empirical results obtained bear upon two main points : (i) Some interaction definitely has prevailed between the municipalities’ fiscal choices made during the observation period, for both taxes; (ii) However, the adjustment reactions to the other municipalities’ fiscal choices have occured over time at the very low yearly pace of 6% and 10% respectively, of the discrepancy between the actual rates and the preferred rates.

La recherche des matières premières susceptibles d'être compostées

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