Search results for " impact"
showing 10 items of 1078 documents
A non-linear Ritz method for the analysis of low velocity impact induced dynamics in variable angle tow composite laminates
2021
Abstract Variable angle tow (VAT) laminates feature composite layers reinforced by fibres following continuous curved paths and offer a wide structural design space for the manufacturing of composite components. In this work, a formulation for the analysis of the impact-induced dynamics in VAT laminated plates is proposed, implemented and tested in this work. The method is based on the adoption of first order shear deformation kinematics and includes von Karman non-linear strains. The discrete system is obtained by employing a pb-2 Ritz series expansion into the Hamilton’s variational statement, while the impact loading is modelled through Hertzian contact law. The resulting non-linear gove…
Suitability of Some Existing Damage Indexes for Regulating Contracts Between Curators of Museums and HVAC Maintenance and Management Companies
2018
Heating, Ventilating and Air-Conditioning (HVAC) systems in museums are called to properly control important microclimate parameters, not only for visitors’ wellbeing, but mostly for works of art preservation. Accordingly, in case of interruptions occurring to HVAC systems, due to maintenance interventions or drawbacks, it is essential to guarantee the shortest possible period of disservice to which possible damages for the works of art are related. In this regard the aim of this work is to introduce a protocol to follow to support curators in regulate the stipulation of contracts with external companies for a more effective management and maintenance of the HVAC systems in order to preserv…
Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal BP for Younger Dryas boundary on four continents
2015
The Younger Dryas impact hypothesis posits that a cosmic impact across much of the Northern Hemisphere deposited the Younger Dryas boundary (YDB) layer, containing peak abundances in a variable assemblage of proxies, including magnetic and glassy impact-related spherules, high-temperature minerals and melt glass, nanodiamonds, carbon spherules, aciniform carbon, platinum, and osmium. Bayesian chronological modeling was applied to 354 dates from 23 stratigraphic sections in 12 countries on four continents to establish a modeled YDB age range for this event of 12,835-12,735 Cal B.P. at 95% probability. This range overlaps that of a peak in extraterrestrial platinum in the Greenland Ice Sheet …
Modelling of laser beam texturing process: experimental and numerical approaches
2007
The aim of this work is to reache a better control of the laser beam surface texturing process on three materials: 304L, TA6V and AA6056 alloys. For this purpose, two complementary methods, experimental and numerical modelling, have been used. As a result of the experimental design approach, it was observed that the laser surface texturing process of 304L and TA6V alloys is strongly influenced by the pulse energy and frequency. In order to obtain a surface roughness Sa < 5 µm for the highest possible productivity it is necessary to work with an energy of 5 mJ and a frequency ranging between 10 and 12 kHz. Unfortunately, for aluminium alloy AA6056, it is necessary to make a choice between ha…
Land use functions — a multifunctionality approach to assess the impact of land use changes on land use sustainability
2008
Part 5. Regional and local evaluation - 17; International audience; The dramatic changes in land use observed in Europe in the last fifty years have generally resulted in improvement of human welfare and economic development. On the other hand, they have caused serious environmental problems. There is therefore a need for approaches that help to understand in an integrative way the economic, environmental and societal impacts that land use changes have on sustainability. Sustainability Impact Assessment(SIA), which assesses the impact of policies on sustainability, addresses this challenge. SIA partly builds on the concept of the multifunctionality of land which helps to deal with the compl…
Holocene fire activity during low-natural flammability periods reveals scale-dependent cultural human-fire relationships in Europe
2018
Abstract Fire is a natural component of global biogeochemical cycles and closely related to changes in human land use. Whereas climate-fuel relationships seem to drive both global and subcontinental fire regimes, human-induced fires are prominent mainly on a local scale. Furthermore, the basic assumption that relates humans and fire regimes in terms of population densities, suggesting that few human-induced fires should occur in periods and areas of low population density, is currently debated. Here, we analyze human-fire relationships throughout the Holocene and discuss how and to what extent human-driven fires affected the landscape transformation in the Central European Lowlands (CEL). W…
A theoretical study of the wet removal of atmospheric pollutants. Part I: the redistribution of aerosol particles captured through nucleation and imp…
1985
Abstract A theoretical model is formulated which allows the processes that control the wet deposition of atmospheric pollutants to be included in cloud dynamic models. The model considers the condensation process and the collision-coalescence process which, coupled together, control the fate of atmospheric aerosol particles removed by clouds and precipitation through nucleation scavenging and impaction scavenging. The model was tested by substituting a simple parcel model for the dynamic framework. In this form the model was used to determine the time evolution of the aerosol particle mass scavenged by drops as well as the aerosol particle mass left unactivated in air as “drop-interstitial”…
Climats tropicaux d'aujourd'hui à demain : variabilité et changements
2008
Present and future tropical climates : their climate variability and their climate changes The oriffttality of tropical climates is re-examined under the light of climate variability and climate change, both present and future . The interannual variability of rainfall is on average larger in the tropics than in the extra-tropics, but it is also spatially more contrasted. Human communities have often responded to this constraint through efficient coping strategies. The regions showing the most variable climate do not necessarily have lower population densities, an indication that in the long run variability is not decisive. However, the recent demographic growth of these regions is often low…
Overall survival impact of BEACOPP versus ABVD in advanced hodgkin lymphoma: a pooled analysis of 4 randomized trials
2016
IF 6.671; International audience
Très longs épisodes secs hivernaux dans le bassin méditerranéen : variabilité spatio-temporelle et impact sur la production céréalière en Espagne.
2018
This study concerns the long winter sequences without rain at the whole Mediterraneanbasin scale. Objectives are (i) to define theses extreme events as geographical and climatological objectscharacterized by a location, a spatial extension and a temporal length and (ii) measured impacts of these eventson the cereal production in Spain. 76 events of very long dry spells (eVLDS) are detected over the 1957-2013period. These eVLDS are grouped into 4 typical recurrent configurations at the Mediterranean basin scale: North-East, West, Scattered & Localised and South-East. The eVLDS have a greater impact on barley, wheat and oatyields (winter crops grown through rainfed agriculture) than rainfall …