1,721,949 research outputs found
Analytical solutions of the balance equation for the scalar variance in one-dimensional turbulent flows under stationary conditions
No full textThis study presents 1D analytical solutions for the ensemble variance of reactive scalars in one-dimensional turbulent flows, in case of stationary conditions, homogeneous mean scalar gradient and turbulence, Dirichlet boundary conditions, and first order kinetics reactions. Simplified solutions and sensitivity analysis are also discussed. These solutions represent both analytical tools for preliminary estimations of the concentration variance and upwind spatial reconstruction schemes for CFD (Computational Fluid Dynamics)-RANS (Reynolds-Averaged Navier-Stokes) codes, which estimate the turbulent fluctuations of reactive scalars. Copyright © 2015 Andrea Amicarelli et al
Numerical study of the daytime planetary boundary layer over an idealized urban area: Influence of surface properties, anthropogenic heat flux, and geostrophic wind intensity
No full textLarge-eddy simulations of an idealized diurnal urban heat island are performed using the Weather Research and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering the anthropogenic heat contribution and the differences of thermal and mechanical properties between urban and rural surfaces. Several cases are simulated together with a reference case, considering different values of the control parameters: Albedo, thermal inertia, roughness length, anthropogenic heat emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in the lower half of the PBL, the shear in the upper half, and the turbulent transport term at the top. The vertical advection of TKE is significant in the upper half of the PBL. The control parameters significantly influence the shape of the profiles of the transport and shear terms in the TKE budget. Bulk properties of the PBL via proper scaling are compared with literature data. A log-linear relationship between the aspect ratio of the heat island and the Froude number is confirmed. For the first time, the effect of relevant surface control parameters and the geostrophic wind intensity on the bulk and turbulent properties of the PBL is systematically investigated at high resolution. © 2016 American Meteorological Society
La foresta degli amanti. Echi e rifrazioni dell'immaginario medievale nel 'salut' Destret d'emors mi clam a vos (codice catalano F)
No full textAnalisi letteraria del 'salut' (codice catalano F)contenente una versione peculiare del tema delle dame amorose premiate/sdegnose punite ricorrente in varie opere mediolatine e romanze
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
Numerical study of the daytime planetary boundary layer over an idealized urban area. Influence of surface properties, anthropogenic heat flux, and geostrophic wind intensity
No full textLarge-eddy simulations of an idealized diurnal urban heat island are performed using the Weather Research
and Forecasting Model. The surface energy balance over an inhomogeneous terrain is solved considering
the anthropogenic heat contribution and the differences of thermal and mechanical properties
between urban and rural surfaces. Several cases are simulated together with a reference case, considering
different values of the control parameters: albedo, thermal inertia, roughness length, anthropogenic heat
emission, and geostrophic wind intensity. Spatial distributions of second-moment statistics, including the
turbulent kinetic energy (TKE) budget, are analyzed to characterize the structure of the planetary boundary
layer (PBL). The effect of each control parameter value on the turbulent properties of the PBL is investigated
with respect to the reference case. For all of the analyzed cases, the primary source of TKE is the buoyancy in
the lower half of the PBL, the shear in the upper half, and the turbulent transport term at the top. The vertical
advection of TKE is significant in the upper half of the PBL. The control parameters significantly influence the
shape of the profiles of the transport and shear terms in the TKE budget. Bulk properties of the PBL via
proper scaling are compared with literature data. A log-linear relationship between the aspect ratio of the
heat island and the Froude number is confirmed. For the first time, the effect of relevant surface control
parameters and the geostrophic wind intensity on the bulk and turbulent properties of the PBL is systematically
investigated at high resolution
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
Human beings influencing assembly line performance: A comparison of job rotation strategies
Full text linkIndustries recently have faced high uncertain market demand with a greater product variety and a shorter life cycle. The primary aim of assembly systems is to increase line efficiency by maximizing the ratio of throughput to incurred costs while maintaining high flexibility. Workers are essential in determining line performance since most assembly tasks are still manual. Consequently, worker diversity plays a critical role in the operation of an assembly line, not only in terms of efficiency and productivity, but also from a human perspective. The human factor has a significant impact on task execution times and the overall production process; in any event, few studies considered human beings in assembly line operations. This study aims to explore the effect of human beings on assembly line performance; the case of an Italian company in which workers' behavior deeply influences production performance is presented, with the aim of analyzing different alternatives for the planning strategy in order to meet this requirement. The studied assembly line consists of three manual workstations and two automated workstations. It operates in a multi-model production environment and has an imbalance level of 50%. The proposal is to manage the allocation of workers through job rotation scheduling to ensure equal treatment despite different levels of efficiency. The study outlines three scheduling alternatives, highlighting the advantages and disadvantages of each
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