Abstract

The environmental impact of civil aviation at low altitudes concerns local air quality, the contribution to global warming and noise nuisances in residential areas located in the vicinity of airports. Aviation is responsible for only a small percentage of man-made CO2 and has a marginal impact on global warming compared to other sources, but the continuous growth of air traffic requires sustainable development to increase, creating economic value with less environmental impact. This research, integrated in the European JTI project Clean Sky, addresses the study of flight departure procedures that minimize the environmental impact of a single aircraft. Departure procedures minimizing perceived noise, the emission of nitrogen oxides and the contribution to the global production of carbon oxides are calculated. From an operational viewpoint, airlines will assign a different priority to each objective and the onboard calculator will provide the most environmental-friendly take-off flight path. These operational constraints entail that the designed algorithm must provide smooth and robust optimal flight paths.

Abstract

International audience; Based on the finite element method, the wave finite element method (WFE) permits to analyze the dynamics of a periodic structure by using a wave decomposition of one period. This method reduces the number of DOF and it has advantages in calculation time. However, it cannot be applied easily to a railway track because this structure is subjected by moving loads which are not considered in a classical WFE. In this article, we present a technique to deal with moving loads applying in a railway track where the track components are modeled by 3D continuous media. By using the classical WFE for one track period in frequency domain, we can rewrite the vector of DOF and loads in a wave base. Then, we can calculate the wave amplitudes of the moving loads from their representation in this base. Thereafter, we apply the wave analyze of WFE to the hold structure. The result shows that the moving loads lead to a sum of wave amplitudes. Finally, we apply this method for a railway track subjected to constant moving loads with numerical application. The new technique permits to analyze the dynamic of railway tracks by considering only one track period.

Abstract

With global warming water issue is becoming a mean problem in areas of the south hemisphere where raining is decreasing considerably. As a result, preserving such resource is becoming a crucial task facing the authorities. One of the main ways of preservation is making the water pipelines network as safe as possible from any damages involving lose of water around urban areas in particular those situated within areas prone to seismicity. For this purpose, a method to assess the seismic vulnerability of water pipelines was developed and implemented in a Geographical Information System (GIS), allowing larger water supply network to be covered and studied. This method is based on the identification of the parameters that have an influence on the behaviour of pipelines. Each parameter having a coefficient that represent its influence on the behaviour of the structure, the product of these parameters represent the seismic vulnerability of the section pipe under study. As a result, a proposed classification is obtained allowing the determination of a safe section (green colour), an unsafe section (red colour) and an intermediate situation (orange colour). For a proposed application of the method, a case study for a town in suburb of Algiers is presented within this paper. It concerns the town of Blida. The results are given in the following sections.