On the effect of different flux limiters on the performance of an engine gas exchange gas-dynamic model

[EN] A suitable tool for the design of intake and exhaust systems of internal combustion engines is provided by time domain non-linear finite volume models. These models, however, are affected by overshoots at discontinuities and numerical dispersion unless some flux limiter is used. In this paper, the effect of the most relevant of such flux limiters on a non-linear staggered-mesh finite-volume model is evaluated. Flux-Corrected-Transport (FCT) and Total Variation Diminishing (TVD) schemes, together with a Momentum Diffusion Term (MDT) are presented for such a model, and the performance of the resulting methods is checked in different problems representative of the influence of engine gas exchange flows on engine performance and intake and exhaust noise. First, two one-dimensional cases are considered: the shock-tube problem, and the propagation of a finite amplitude pressure pulse. Secondly, a simple but representative three-dimensional geometry is studied. From the results obtained, it can be concluded that, even if none of the methods is able to handle properly the three problems considered, the FCT method provides the best overall performance. (C) 2017 Elsevier Ltd. All rights reserved.M. Hernandez is partially supported through contract FPI-S2-2015-1064 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Torregrosa, AJ.; Broatch, A.; Arnau Martínez, FJ.; Hernández-Marco, M. (2017). On the effect of different flux limiters on the performance of an engine gas exchange gas-dynamic model. International Journal of Mechanical Sciences. 133:740-751. https://doi.org/10.1016/j.ijmecsci.2017.09.029S74075113

Stellar Astrophysics and Exoplanet Science with the Maunakea Spectroscopic Explorer (MSE)

The Maunakea Spectroscopic Explorer (MSE) is a planned 11.25-m aperture facility with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. A rebirth of the 3.6m Canada-France-Hawaii Telescope on Maunakea, MSE will use 4332 fibers operating at three different resolving powers (R ~ 2500, 6000, 40000) across a wavelength range of 0.36-1.8mum, with dynamical fiber positioning that allows fibers to match the exposure times of individual objects. MSE will enable spectroscopic surveys with unprecedented scale and sensitivity by collecting millions of spectra per year down to limiting magnitudes of g ~ 20-24 mag, with a nominal velocity precision of ~100 m/s in high-resolution mode. This white paper describes science cases for stellar astrophysics and exoplanet science using MSE, including the discovery and atmospheric characterization of exoplanets and substellar objects, stellar physics with star clusters, asteroseismology of solar-like oscillators and opacity-driven pulsators, studies of stellar rotation, activity, and multiplicity, as well as the chemical characterization of AGB and extremely metal-poor stars.Comment: 31 pages, 11 figures; To appear as a chapter for the Detailed Science Case of the Maunakea Spectroscopic Explore

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

An optimal battery sizing algorithm for future aircraft systems studies

International audienceThe path to climate-friendly aviation is a difficult way that needs to be traveled fast. A considerable and immediate drop of fossil fuels consumption is necessary to respect the Paris Agreement. Hybrid-electric and full-electric aircraft are part of the solution but developing a reliable and profitable hybrid-electric regional aircraft is a complex task. The European research project FUTPRINT50 aims at developing methods and tools to help to achieve this goal. The battery system is one of the key elements of aircraft electric architectures as it stores energy for propulsion and auxiliary systems. Among other challenges, optimal sizing (including mass, electric performances and aging) and safety are the two most difficult aspects to overcome. Herein, we propose a battery sizing algorithm, integrated to a plane level optimization tool (SUAVE), which, for a given power profile, optimizes battery systems sizing including all above cited parameters.The sizing algorithm is based on a three steps strategy:1.Optimal battery sizing for a given power profile: Optimal series/parallel configuration that includes battery aging and nominal thermal management. At this step the total battery mass is estimated with a scalar coefficient. This is the standard approach for mass evaluation. It gives high uncertainty.2.Optimal battery sizing including thermal runaway non propagationWe assure that in case of a thermal runaway of a cell, there is no propagation inside the battery pack. Two parameters are taken into account: cell-to-cell distance and thermal insulation material. Total battery mass is then refined a first time.3.Optimal battery sizing including battery casing sizing. Based on actual experimental data, an analytical model of the battery casing helps to determine the optimal casing thickness. Besides Finite Element Analysis models based on a CAD battery casing under pressure, contributes to supports the analytical model through several safety module tests, including thermal runway of a cell inside the casing. A refined battery mass evaluation is then possible.The reduced battery cell model is built up using several simulations of an electric equivalent circuit model of a cell (fixed chemistry, format and specifications) parametrized by testing. This model is then used to run an optimal battery sizing, finally taking into account performance targets (mass, volume, voltage, power), aging and safety

An optimal battery sizing algorithm for future aircraft systems studies

International audienceThe path to climate-friendly aviation is a difficult way that needs to be traveled fast. A considerable and immediate drop of fossil fuels consumption is necessary to respect the Paris Agreement. Hybrid-electric and full-electric aircraft are part of the solution but developing a reliable and profitable hybrid-electric regional aircraft is a complex task. The European research project FUTPRINT50 aims at developing methods and tools to help to achieve this goal. The battery system is one of the key elements of aircraft electric architectures as it stores energy for propulsion and auxiliary systems. Among other challenges, optimal sizing (including mass, electric performances and aging) and safety are the two most difficult aspects to overcome. Herein, we propose a battery sizing algorithm, integrated to a plane level optimization tool (SUAVE), which, for a given power profile, optimizes battery systems sizing including all above cited parameters.The sizing algorithm is based on a three steps strategy:1.Optimal battery sizing for a given power profile: Optimal series/parallel configuration that includes battery aging and nominal thermal management. At this step the total battery mass is estimated with a scalar coefficient. This is the standard approach for mass evaluation. It gives high uncertainty.2.Optimal battery sizing including thermal runaway non propagationWe assure that in case of a thermal runaway of a cell, there is no propagation inside the battery pack. Two parameters are taken into account: cell-to-cell distance and thermal insulation material. Total battery mass is then refined a first time.3.Optimal battery sizing including battery casing sizing. Based on actual experimental data, an analytical model of the battery casing helps to determine the optimal casing thickness. Besides Finite Element Analysis models based on a CAD battery casing under pressure, contributes to supports the analytical model through several safety module tests, including thermal runway of a cell inside the casing. A refined battery mass evaluation is then possible.The reduced battery cell model is built up using several simulations of an electric equivalent circuit model of a cell (fixed chemistry, format and specifications) parametrized by testing. This model is then used to run an optimal battery sizing, finally taking into account performance targets (mass, volume, voltage, power), aging and safety

Application of a variable structure model in observation and control of an anaerobic digestor

NRC publication: Ye

Rehabilitation project of a managed marsh: Biodiversity assessment of different management measures

International audienc

Effector Mimics and Integrated Decoys, the Never-Ending Arms Race between Rice and Xanthomonas oryzae

BGPI : équipe 4Plants are constantly challenged by a wide range of pathogens and have therefor evolved an array of mechanisms to defend against them. In response to these defense systems, pathogens have evolved strategies to avoid recognition and suppress plant defenses (Brown and Tellier, 2011). Three recent reports dealing with the resistance of rice to Xanthomonas oryzae have added a new twist to our understanding of this fascinating co-evolutionary arms race (Ji et al., 2016; Read et al., 2016; Triplett et al.,2016). They show that pathogens also develop sophisticated effector mimics to trick recognition