1,720,994 research outputs found
Time series clustering from road transport CO2 emission
No full textCarbon dioxide (CO2) pollution has long been considered a severe environmental issue. In particular, the Road Transport sector has been recognized as one of the biggest contributors to emitting carbon emissions. In tackling climate change, the Kyoto Protocol was signed by developed and developing countries and represents a voluntary international treaty that aims to reduce carbon emissions. This work seeks to identify similarities in trend emission performance among 31 countries that ratified the agreement. The data come from the Emissions Database for Global Atmospheric Research, which contains the annual values of polluting gas emissions from 1970 to 2018. To do this, time series cluster analyses have been applied using two distance measures and considering different sub-periods
Detecting leaders country from road transport emission time-series
Full text linkNowadays, climate change and global warming have become the main concerns world-wide. One of the main causes are the greenhouse gas (GHG) emissions produced by human activities, especially by the transportation sector. The adherence to international agreements and the implementation of climate change policy are necessary conditions for reducing environmental problems. This paper investigates the lead–lag relationship between Organization for Economic Co-operation and Development (OECD) and Annex I member countries on road transport emission performance focusing on the statistical analysis of the lead–lag relationships between the road transport emission time-series from 1970–2018 extracted by the Emissions Database for Global Atmospheric Research (EDGAR) database. The analysis was carried out using the cross-correlation function between each pair of the countries’ time-series considered. Empirical results confirm that some nations have been playing a role as leaders, while others as followers. Sweden can be considered the leader, followed by Germany and France. By analyzing their environmental policy history, we can figure out a common point that explains our results
The role of gear layout and meshing phase for whine noise reduction in ordinary geartrains
No full textWhine noise is one of major concern within geared system dynamics. The time-varying bearing forces are transmitted to the gearbox case, which coupled with the whole system assembly provokes an undesired noise emission. The paper proposes an analytical formulation able to forecast the main overall direction and magnitude of bearing reaction forces on idler gear when the geartrain works under quasi-static condition. Moreover, a parametric study is conducted by evaluating the influence of geartrain layout, the meshing phase shift and the amplitudes of meshing forces. Finally, numerical experiments are performed in order to evaluate discrepancies and similarities when the inertial effects become relevant
A rattle index formulation for single and multiple branch geartrains
No full textThe paper proposes an analytical procedure for the generalization of the rattle index in any type of ordinary transmission layouts, single or multiple branch, both in idle and loaded conditions. Its definition is obtained by a recursive analytical formulation of the rotational dynamics of gears. Numerical analytical studies are exploited to examine the effectiveness and reliability of the introduced index. Several geartrain layouts are investigated and results show its capability to instantaneously describe the vibro-impact events related to any gear pair of the driveline. Moreover, the general definition is shown to be a proper indicator of the potential presence of mutual interactions between different gear pairs pertaining to the same driveline. The analysis of the results reveals an excellent agreement with the expected behavior of the outlined parameter
A model-based approach for gear train whine noise reduction by mesh phasing modification
No full textHeavily loaded gear trains are known to produce a characteristic whine noise and vibration signature, which radiates through the bearings producing an undesired noise emission affecting the NVH behavior of the overall machine. This phenomenon is generated by the variable mesh stiffness and the static transmission error of the gear pairs in mesh within the gear train, but its magnitude strongly depends on how the meshing processes combine between each others. In this context, the present work proposes an analytical methodology to predict amplitude and direction of the variable loads applied on the bearings of idle gears, assuming quasi-static conditions. The dissertation demonstrates that the multiple mesh forces produce a variable load on idle gear bearings describing an ellipse whose shape depends on various geometrical parameters of the system. Numerical examples are shown to assess the potentials of the method and highlight how gear train spatial layout and phasing between different meshings may be used during gearbox design projects to limit the emitted noise of the gear train
THE IMPACT OF YOUTH GUARANTEE FOR RURAL NEETS -WHO PARTICIPATES IN PUBLIC EMPLOYMENT SERVICES AND WITH WHAT EFFECTS? A STUDY ON ITALY, POLAND, AND ROMANIA
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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