ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Residual stress & Finite element method. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Analogies between Internet network and logistics service networks: challenges involved in the interconnection

Abstract: Logistics networks that are currently formed by supply chains are intertwined but remain heterogeneous and not very interconnected. In computer networks, this stage was overtaken with the arrival of Internet. In this paper we explore the possible analogies and transpositions between computer networks, in particular Internet, and logistic networks. To this end, a new logistical concept was proposed: Physical Internet that aims at the interconnection of networks of logistic services. In fact, there are strong similarities between these networks in spite of the basic differences in the type of objects that prevent an integral transposition. To illustrate the pertinence of this analogy, the authors illustrate the interconnection potential of logistics networks with a stylised model. In view of the exploratory nature of this work, this impact will be assessed by means of an analytic model based on a method of continuous approximations. This illustration provides an indication of the potential inherent in the interconnection of logistics networks.

Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach

Abstract: Fisheries management agencies have to drive resources on sustainable paths, i.e. within defined boundaries for an indefinite time. The viable-control approach is proposed as a relevant method to deal with sustainability. We analyse the ICES precautionary approach (PA) by means of the notion of viability domain, and provide a mathematical test for sustainability. It is found that the PA based on spawning-stock biomass (SSB) and fishing mortality (F) indicators is sustainable only when recruits make a significant contribution to SSB. In this case, advice based upon SSB, with an appropriate reference point, is sufficient to ensure sustainability. In all other cases, SSB is not a sufficient metric of stock productivity and must be complemented with other management indicators to ensure sustainability. The approach is illustrated with numerical applications to the northern hake and Bay of Biscay anchovy.

Ensemble averaging stress–strain fields in polycrystalline aggregates with a constrained surface microstructure – Part 1: anisotropic elastic behaviour

Abstract: The effect of three-dimensional (3D) grain morphology on the deformation at a free surface in polycrystalline aggregates is investigated by means of a large-scale finite element and statistical approach. For a given two-dimensional surface at z = 0 containing 39 grains with given crystal orientations, 17 random 3D polycrystalline aggregates are constructed having different 3D grain shapes and orientations except at z = 0, based on an original 3D image analysis procedure. They are subjected to overall tensile loading conditions. The resulting stress–strain fields at the free surface z = 0 are analyzed. Ensemble average and variance maps of the stress field at the observed surface are computed. In the case of an anisotropic elastic behaviour of the grains, fluctuations ranging between 5% and 60% are found in the equivalent stress level at a given material point of the observed surface from one realization of the microstructure to another. These results have important implications in the way of comparing fin...

Comprehensive post-event survey of a flash flood in Western Slovenia: observation strategy and lessons learned

Abstract: The limited extent of the areas affected by flash floods and strong spatial and temporal gradients of rainfall cause conventional measurement networks of rain and discharges to be inadequate for an effective observation of these events. The documentation of flash floods urges post-event survey strategies encompassing accurate radar rainfall estimation, field observations of the geomorphic processes associated to the flood, indirect reconstruction of peak discharges and interviews of eyewitnesses. This paper describes the methods applied and the results achieved in the survey of a flash flood that occurred on 18th September 2007 in the Selka Sora watershed (Western Slovenia). The documentation of this flash flood reveals high peak flood discharges and unit peak discharges and a complex flood response. Observations on geomorphic activity show widespread erosion and debris flows, although generally involving relatively small debris volumes. Relevant amounts of large wood were mobilised, with a large variability of the intensity of supply processes. The field study of the Selka Sora flash flood outlines the importance of geomorphological surveys as a prerequisite for flood discharge reconstruction in mountainous watersheds with active sediment dynamics, the basic role of the accounts of eyewitnesses of the flood, and the need of qualitycontrolled weather radar, which permit coupling field observations with rainfall-runoff modelling.