1,151 research outputs found
Geometric Properties of Randers and Other Changes of Rizza Manifolds
No full text[[abstract]]In this paper we study the β-change of Rizza manifold associated with the generalized Finsler metric. It is proved that Randers change preserves the C-reducibility. We consider the Randers-change (superscript *)L=L+β and proved the conditions for Rizza manifold to be C-reducible, Berwald and Landsbergian. Also we obtain condition for Rizza manifold to be C-conformal to a locally Minkowski space
Pragmatiche della sicurezza sul lavoro fra pratiche organizzative e discorsi
No full textL'articolo, esito di una procedura di peer review della rivista Sociologia del lavoro (rivista di fascia A nei settori scientifici 14/C1-C2-D1) è il prodotto di una ricerca PRIN sul tema “La qualità dell’argomentazione pubblica: discorsi, pratiche, istituzioni”, coordinata da F. Rositi, Università di Pavia e che ha coinvolto le università di Milano Bicocca (O. de Leonardis; W. Privitera); Milano Statale (G. Procacci, R. Escobar), Bologna Alma Mater Sudiorum (V. Borghi, R. Rizza, B. Giullari). Il tema trattato è quello del rapporto tra sicurezza e lavoro, con particolare attenzione alla circolarità tra discorsi, pratiche e processi organizzativi. A questo scopo si fa riferimento al concetto di campo organizzativo, analizzando l’evoluzione storica del quadro normativo, gli attori individuali e collettivi che intervengono in questo campo influenzandosi a vicenda, e le culture organizzative della sicurezza che emergono. Si tratta di un tentativo di sistematizzare in chiave di sociologia dei processi economici, del lavoro e dell’organizzazione, il tema del rapporto fra salute-sicurezza e lavoro, altrimenti dominato da una letteratura di tipo medico, giuridico e psicologico
Variability of airborne particle metrics in an urban area
No full textIn the present study a mobile monitoring approach (i.e. bike with onboard instruments) was proposed and applied to investigate the spatial variability of all the key airborne particle metrics in an Italian urban area from a statistical point of view. Particle number, alveolar-deposited surface area, and PM<sub>10</sub> concentrations were measured through hand-held monitors and compared to simultaneous background concentrations by means of non-parametric tests and further post-hoc tests (Kruskal-Wallis test). Streets characterized by exposure levels statistically higher than the background levels for all the particle metrics were identified for different seasons in a pilot urban area (Cassino, Italy). A higher number of hot spots was detected for metrics affected by ultrafine particles (i.e. number and alveolar-deposited surface area concentrations) with respect to PM<sub>10</sub>. The effect of metrological requirements of the instrumentation on the proposed method was also discussed
Purification and molecular characterization of a novel protein factor from Phytophthora cactorum causing toxicity in plant
No full textPowder bed fusion with electron beam: The interplay of sintering, porosity, and coordination number in modelling the powder thermal conductivity through a novel tortuosity formulation
No full textFor the powder bed fusion with electron beam (PBF-EB) additive manufacturing, properties such as the thermal conductivity of the material surrounding the melting area are critical. Thermal conductivity is influenced by the extremely high temperature reached in a short time and distributed in the building area. This fast temperature growth produces sintering phenomena and the creation of a neck between the particles. Because of this sintering, measuring the thermal conductivity at the process conditions is challenging. This paper proposes an analytical formulation for estimating the effective powder bed thermal conductivity at the PBF-EB conditions, introducing a novel modelling strategy for the tortuosity factor. In a changing net of sintered powder particles, the proposed model for the tortuosity factor considers the neck evolution and the complexity of the heat transfer due to the several heat paths possible through the particle net. To show the effectiveness of the proposed model, the thermal conductivity is evaluated for three 3D structures characterised by an increasing number of powder particles and heat path complexity: a simple cubic, a body centred cubic and a portion of a powder bed. It is shown that thermal conductivity strongly depends on the arrangement of the particles in 3D space, the structure density and the complexity of the heat diffusion path (tortuosity). Also, the numerical results from the proposed model show good agreement when compared with finite element analysis and experimental literature data
Re: "regulation of S-Nitrosylation in Aging and Senescence" by Larrick and Mendelsohn (Rejuvenation Res 2019;22:171-174)
No full textPhase-field simulation of particles rigid body motion at the early stage of sintering in powder bed fusion with electron beam: A proposal for computational efficiency
No full textThe sintering of powder particles prior to full melting is a defining feature of the powder bed fusion with electron beam (PBF-EB) process, distinguishing it from other metal additive manufacturing techniques. Sintering involves the movement of atoms toward contact points between adjacent particles, leading to neck formation and growth. This atomic movement is driven by the high working temperatures of PBF-EB, which activate diffusion mechanisms and induce rigid body motion (RBM) of particles. While research on the numerical analysis of diffusion is growing, the motion of the particles occurring during the PBF-EB and its relevance are still unexplored. This work uses a phase field model to capture the physics of early-stage sintering in PBF-EB, incorporating both diffusion and RBM driven by vacancy migration. The influence of RBM parameters on neck formation and growth during the sintering of Ti6Al4V particles under PBF-EB conditions is investigated. Simulations encompass different process phases and durations (from seconds to hours), including the preheating of the layer and the cooling of the build. In addition, this work addresses the computational challenges of modelling RBM and proposes a novel approach to enhancing diffusion coefficients to emulate RBM effects, significantly reducing simulation times. Results indicate that incorporating RBM accelerates sintering and leads to larger neck formation compared to diffusion alone, although computational time increases by 30 %. Consequently, RBM should be prioritised in scenarios where its impact is critical, such as the preheating phase of PBF-EB. In contrast, during the process, the neck growth can be analysed by the novel proposed approach which significantly enhances computational efficiency while effectively capturing the influence of RBM on neck growth
On ‘grapheme’: recurrent problems and new reflections
No full textSome problems connected to the term/concept 'grapheme' are reviewed. The major point concerns the question of the dependency of writing from speech or language. We distinguish between a semiotic dependency and an epistemological one. A writing system is a code, most of this code, in glottographic systems, re-codes the code of a given language (mainly the phonological one): in this sense we accept the concept of dependency of writing system (especially glottographic). The relation between grapheme and phoneme, however, is shown to be more epistemological than semiotic. We try to overcome this. The anthropological model offers solutions that are particulary interesting for ancient scripts. We intro-duce a concept of grapheme that covers different areas of functions: from the core glottographic to the visual one
The Cherokee ‘vulgate’. A critical premise to the historical study of the Cherokee writing system
No full textThe essay proposes a critical premise for the historical study of Cherokee writing. The Cherokee syllabary can only be historically understood if it is brought back to the historical dynamics of the time in which it was designed. The history of writing systems, however, has been primarily concerned with the invention of the script, often giving uncritical credit to reports about the biography of its inventor. In particular, we critically consider the important work of I. Gelb, who saw the process of invention of the Cherokee (and other comparable scripts) as confirming the evolutionary history of writing. Anecdotal evidence around Sequoyah proves central to understanding the reception of the syllabary and its invention at the academic level. Our conclusions provide an outline of the interrelationship among the different themes of the vulgate and identify Sequoyah's métissage theme as a mirror image of the hybrid nature of the script. This parallelism tells a great deal about the dynamics, including tragic ones, of the history of the period, a topic we will address in a future paper
- …
