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.

Self-healing umbrella sampling: convergence and efficiency

Abstract: The Self-Healing Umbrella Sampling (SHUS) algorithm is an adaptive biasing algorithm which has been proposed in Marsili et al. (J Phys Chem B 110(29):14011---14013, 2006) in order to efficiently sample a multimodal probability measure. We show that this method can be seen as a variant of the well-known Wang---Landau algorithm Wang and Landau (Phys Rev E 64:056101, 2001a; Phys Rev Lett 86(10):2050---2053, 2001b). Adapting results on the convergence of the Wang-Landau algorithm obtained in Fort et al. (Math Comput 84(295):2297---2327, 2014a), we prove the convergence of the SHUS algorithm. We also compare the two methods in terms of efficiency. We finally propose a modification of the SHUS algorithm in order to increase its efficiency, and exhibit some similarities of SHUS with the well-tempered metadynamics method Barducci et al. (Phys Rev Lett 100:020,603, 2008).

A Paradigm Change in Road Safety Evaluation: From Hypothetico-Deductive Testing To Designing Safety Systems

Abstract: Automobile industry is going through important changes with the rise of connected vehicle paradigm. In this context, traditional performance evaluation procedures are becoming obsolete or insufficient. This is particularly the case for road safety evaluation models since new information and communication technologies engender new types of vulnerabilities. This paper claims that traditional hypothetico-deductive evaluation paradigms are no longer adequate to assess road safety. To complement this traditional approach, we present an alternative perspective based on design theory originating from engineering design field. We illustrate the use of design methods in this context. More generally, we argue that a design based approach to road safety evaluation will allow integrating evaluators early in the process, and to give them a set of new tools coming from design theory in order to design better experiments with indicators of safety are better adapted to changing safety situations.

Centralized self-optimization of pilot powers for load balancing in LTE

Abstract: Optimization of radio access networks is a challenge for cellular operators. With the deployment of new radio access technologies and advanced features, network optimization needs to be automated for performance improvement and OPerational EXpenditures (OPEX) reduction. In this paper, we propose a method for centralized self-optimization of pilot powers to perform load balancing between base stations. The proposed method uses a stochastic surrogate function to model the functional relationships between noisy Key Performance Indicators (KPIs) and network parameters, and subsequently performs optimization using a pattern search algorithm in a recursive manner. The method is applied to solve a high dimensional optimization problem of pilot power based load balancing in an LTE network. Results obtained using a flow level analytical network simulator show the advantages of the proposed recursive modeling and optimization approach as a promising solution in terms of robustness to noisy data and fast convergence to the optimum point for a high dimensional network optimization.

Interference Analysis in Dynamic TDD System Combined or not With Cell Clustering Scheme

Abstract: Dynamic Time Division Duplex (TDD) has been introduced as a solution to deal with the uplink and downlink traffic asymmetry, mainly observed for dense heterogeneous network deployments. However, the use of this feature requires new interference mitigation schemes capable to handle two additional types of interferences between cells in opposite transmission cycle: downlink to uplink and uplink to downlink interferences. Among them, Cell clustering has been proposed as an efficient solution to minimize inter-cell interferences in opposite transmission directions and somehow responds to the requirements of enhanced Interference Mitigation and Traffic Adaptation (eIMTA) problem. This work is devoted to provide a new analytical approach to model inter-cell interferences and quantify performances of Dynamic TDD system in terms of SINR (Signal to Interferences plus Noise Ratio) distribution. Analytical system performance investigation concerns two scenarios: i) basic Dynamic TDD without any other feature and ii) Dynamic TDD with interference mitigation schemes.