ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Residual stress. 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.

On failure mode and shear behavior of rock mass with interlayer staggered zone

Abstract: Because of existence worldwide of interlayer staggered zone,there have been many engineering rock mass stability problems and geological disasters occurred over the world.In this paper,some cases of distortion failure or destruction of engineering rock mass structure induced by interlayer staggered zone are summarized.Rock mass structure controlling theory is adopted to categorize the failure modes of rock mass with staggered zone into tension crack failure,block-fall and interfacial shear slip failure.After that,it is shown that shear strength model is the main point when modeling for the mechanical behavior of interlayer staggered zone.A deep review of the existing test methods and the modeling theory for its shear behavior shows that the elasto-viscoplastic model is the fundamental constitutive model for describing the mechanical behavior of interlayer staggered zone.

Keratin/Hydrotalcites Hybrid Sponges as Promising Adsorbents for Cationic and Anionic Dyes.

Abstract: In this work, keratin sponges were prepared by freeze-drying method and tested for adsorption of Azure A and Methyl Orange dyes. The obtained materials showed a porosity of 99,92% and a mean pore size dimension of about 91μm. The use of oxidized sucrose with a heating treatment at 150°C was demonstrated to be a useful crosslinking procedure alternative to the conventional glutaraldehyde. Keratin sponges showed a maximum adsorption capacity of 0.063 mmol/g and of 0.037 mmol/g for Azure A and Methyl Orange, respectively. The absorption of the cationic dye AzureA onto keratin sponges was better described by Freundlich model while the isotherm adsorption of the anionic Methyl Orange was found to correlate with both Langmuir and Freundlich models. The mean free energies evaluated by using the D-R model indicated a physisorption of Methyl Orange and a chemisorptions of Azure A onto keratin sponges. Finally, the functionalization of keratin sponges with Zn Al hydrotalcites nanoparticles did not affect the adsorption performances of the adsorbent towards the cationic dye Azure A, while it improved those towards the anionic Methyl Orange, increasing the related removal efficiencies from 43% to 96%. Collectively, the reported data indicates that the combination of keratin with hydrotalcites nanoparticles is a good strategy to obtain more functional adsorbent materials of potential interest for water treatment and purification.

Optimal control design for Modular Multilevel Converters operating on multi-terminal DC Grid

Abstract: This paper proposes an advanced control strategy for Modular Multilevel Converters (MMC) integrated in Multiterminal DC grid. In this present work, a three terminal MMC-MTDC system connecting onshore AC systems with an offshore wind farm is setup. Firstly, the voltage droop control associated to the conventional cascaded controllers for MMC stations is studied, the dynamic behavior of the DC voltage is analyzed and some drawbacks are outlined. In order to improve the dynamic behavior of the controlled DC bus voltage and the stability of MTDC system, an optimal multivariable control strategy of each MMC converter is proposed and integrated in a voltage droop controller strategy. The designed advanced controller allows to improve the overall DC grid stability and to reach the droop values designed on static considerations with acceptable dynamic behavior. By means of numerical simulations in EMTP-RV software, it is shown that the proposed control strategy performs well the stability of MTDC grid with 400-level model for MMC compared with the classic existing control methods.

3D Road Environment Modeling Applied to Visibility Mapping: An Experimental Comparison

Abstract: Sight distance along the pathway plays a significant role in road safety and in particular, has a clear impact on the choice of speed limits. Mapping visibility distance is thus of importance for road engineers and authorities. While visibility distance criteria are routinely taken into account in road design, few systems exist for evaluating them on existing road networks. Most available systems comprise a target vehicle followed at a constant distance by an observer vehicle. This only allows to check if a given, fixed visibility distance is available: estimating the maximum visibility distance requires several passages, with increasing inter-vehicle intervals. We propose two alternative approaches for estimating the maximum available visibility distance, that exploit 3D models of the road and its close environment. These methods involve only one acquisition vehicle and use either active vision, more specifically 3D range sensing (LIDAR), or passive vision, namely, stereovision. The first approach is based on a Terrestrial LIDAR Mobile Mapping System. The triangulated 3D model of the road and its surroundings provided by the system is used to simulate targets at different distances, which allows for estimation of the maximum geometric visibility distance along the pathway in a quite flexible way. The second approach involves the processing of two views taken by digital cameras on-board an inspection vehicle. After road segmentation, the 3D road model is reconstructed which allows maximum roadway visibility distance estimation. Both approaches are described, evaluated and compared. Their pros and cons with respect to vehicle-following systems are also discussed.

A tight sufficient condition for Radner-Stiglitz nonconcavity in the value of information

Abstract: This paper deals with the existence of a nonconcavity in the value of information, as was first explained by Radner and Stiglitz [A nonconcavity in the value of information, in: M. Boyer, R.E. Kihlstrom (Eds.), Bayesian Models in Economic Theory, Elsevier Science Publishers, Amsterdam, 1984, pp. 33-52 (Chapter 3)]. After defining infinitesimal information distance variationIIDV, we find that IIDV = 0 is sufficient for a zero marginal value of information at the null. This is a condition only on the information structure and in particular is independent of the decision maker's preferences. This condition is tight: when IIDV > 0, there exists a payoff function for which the marginal value of information at the null is positive under general assumptions. © 2007.