A Stochastic Model for Chain Collisions of Vehicles Equipped With Vehicular Communications

Improvement of traffic safety by cooperative vehicular applications is one of the most promising benefits of vehicular ad hoc networks (VANETs). However, to properly develop such applications, the influence of different driving parameters on the event of vehicle collision must be assessed at an early design stage. In this paper, we derive a stochastic model for the number of accidents in a platoon of vehicles equipped with a warning collision notification system, which is able to inform all the vehicles about an emergency event. In fact, the assumption of communications being used is key to simplify the derivation of a stochastic model. The model enables the computation of the average number of collisions that occur in the platoon, the probabilities of the different ways in which the collisions may take place, as well as other statistics of interest. Although an exponential distribution has been used for the traffic density, it is also valid for different probability distributions for traffic densities, as well as for other significant parameters of the model. Moreover, the actual communication system employed is independent of the model since it is abstracted by a message delay variable, which allows it to be used to evaluate different communication technologies. We validate the proposed model with Monte Carlo simulations. With this model, one can quickly evaluate numerically the influence of different model parameters (vehicle density, velocities, decelerations, and delays) on the collision process and draw conclusions that shed relevant guidelines for the design of vehicular communication systems, as well as chain collision avoidance applications. Illustrative examples of application are provided, although a systematic characterization and evaluation of different scenarios is left as future work.This work was supported in part by the MICINN/FEDER project under Grant TEC2010-21405-C02-02/TCM (CALM) and in part by Fundación Seneca RM under Grants 00002/CS/08 FORMA and 04549/GERM/06. The work of J. Garcia-Haro was supported by Grant PR2009-0337. The work of E. Egea was supported by the Universidad Politécnica de Cartagena under Grant PMPDI-UPCT-2011. The work of J. Tomas- Gabarron was supported by Grant AP2008-02244. The work of C. Garcia-Costa was supported by Grant 12347/FPI/09

Improving long line stability by integrating renewables using static synchronous generators

Postprint (author's final draft

Supporting phase stability on interconnected grids by synchronous renewable virtual power plants

Rapid growing on the power level of renewable generation units leads to that using more adaptable and flexible control techniques in this units becomes more important for grid operators. In this paper, after introducing Renewable Static Synchronous Generation Units (RSSGU) as units with flexible dynamics capability, forming of renewable Virtual Power Plants based on this RSSGUs (VPP-SSG) is suggested as a solution for overcoming phase stability challenges on interconnected generation areas. Based on the dynamic modeling and small signal analysis, an algorithm is presented for the dynamic designing of VPP-SSGs aims to provide supporting damping for both local and interarea oscillatory modes. Modal analysis and time domain study on active powers inside of generation areas and tie lines on two area system using Simulink confirms that these type of VPP-SSGs can support phase stability on power grid with interconnected generation areasPeer ReviewedPostprint (author's final draft

Using small mammals to reconstruct the climatic context of the late pleistocene Lagar Velho Rockshelter (Leiria, Portugal).

To reconstruct the climatic conditions of the Lagar Velho rockshelter during the late Pleistocene, we applied the bioclimatic model to the rodent assemblages, mainly composed of the vole species Arvicola sapidus, Microtus arvalis, Microtus agrestis, Microtus (Terricola) lusitanicus and Microtus (Iberomys) cabrerae and the field mouse Apodemus sylvaticus. Based on the distribution of these species by layers and percentages, considering different climate-types, and applying a series of functions, it was possible to estimate the mean annual temperature (MAT), the mean temperature of the coldest month (MTC), the mean temperature of the warmest month (MTW) and the mean annual precipitation (MAP). For comparative purposes, the resulting parameters were compared with climate data obtained for the last 30 years from nearby meteorological stations in order to attain averages and observe climatic fluctuations. The climatic parameters were then compared with the Köppen-Geiger classification in order to contrast our data with the current climate-types. Finally, we combined the results with chronological and environmental information to produce a climate framework within Marine Isotope Stage 2 (MIS 2)

Enantioselective Palladium-Catalyzed [3C + 2C] and [4C + 3C] Intramolecular Cycloadditions of Alkylidenecyclopropanes

NOTICE: This is the peer reviewed version of the following article: Felipe Verdugo, Lara Villarino, Juan Durán, Moisés Gulías, José L. Mascareñas and Fernando López (2018), Enantioselective Palladium-Catalyzed [3C + 2C] and [4C + 3C] Intra-molecular Cycloadditions of Alkylidenecyclopropanes. ACS Catalysis, 2018, 8, 6100–6105 [DOI: 10.1021/acscatal.8b01296]. This article may be used for non-commercial purposes in accordance with American Chemical Society Terms and Conditions for self-archivingWe report a highly enantioselective [3C + 2C] intramolecular cycloaddition of alkylidenecyclopropanes (ACPs) and alkenes. The best results are obtained by using sterically demanding chiral phosphoramidite ligands derived from Vapol. Moreover, we also show that related, but less bulky, phosphoramidites can also lead to very effective [4C + 3C] cycloadditions when dienes, instead of alkenes, are used as reacting partners. The reactions provide a practical, simple, and selective access to optically active, synthetically appealing 5,5- and 5,7-bicyclic systemsThis work received financial support from the spanish MINECO grants (Nos. SAF2016-76689-R, CTQ2016-77047-P, CTQ2017-84767-P, FPU to L.V. and J.D.), Xunta de Galicia (Nos. ED431C 2017/19, 2015-CP082, and Centro Singular de Investigación de Galicia accreditation 2016-2019 ED431G/09), the ERDF and ERC (Adv. Grant No. 340055). The Orfeo-Cinqa network CTQ2016-81797-REDC, CONICYT-Becas Chile (Ph.D. grant to F.V.) and Sarah Walker (preliminary work) are also acknowledgedS

Registres ornitològics 2007

Abstract not availabl