496 research outputs found
Chiovenda Piola Caselli Lucia
No full textChiovenda Piola Caselli Lucia; profilo e impegno educativo nell'ambito dell'Associazione Guide Italiane
ANALYSIS OF A COMBINED CYCLE EXPLOITING INLET CONDITIONING TECHNOLOGIES FOR POWER MODULATION
No full textThe high share of non-dispatchable renewable energy source generators in the electrical grid has increased the need for flexibility of Gas Turbine Combined Cycles (GTCC) already installed. To maximize not only the maximum power produced, via Power Augmentation Technologies (PATs), but also to reduce the Minimum Environmental Load (MEL), both OEMs and GTCC owners have adopted several technical solutions. This kind of flexibility has become, year-by-year, ever more crucial to guarantee GTCC economical sustainability. Amongst the solutions which can be adapted to guarantee GTCC flexibility, the Inlet Conditioning System is a particularly interesting technical solution, which can be installed without restrictions related to the different GT design.In this paper, an evaluation of the compressor inlet temperature effect over the Combined Cycle performance is presented, with a focus on the bottoming Cycle impact. Different Inlet Conditioning Strategies are then compared considering the energy, and the environmental impact on GTCC behavior. The performance of a layout including a Thermal Energy Storage (TES) and a Heat Pump (HP) is then evaluated and compared to other technical solutions
Supervised versus unsupervised antimalarial treatment with six-dose artemether-lumefantrine: pharmacokinetic and dosage-related findings from a clinical trial in Uganda.
No full textBACKGROUND: A six-dose antimalarial regimen of artemether-lumefantrine (A/L) may soon become one of the most widely used drug combination in Africa, despite possible constraints with adherence and poor absorption due to inadequate nutrition, and a lack of pharmacokinetic and effectiveness data. METHODS: Within a trial of supervised versus unsupervised A/L treatment in a stable Ugandan Plasmodium falciparum transmission setting, plasma lumefantrine concentrations were measured in a subset of patients on day 3 (C [lum]day3) and day 7 (C [lum]day7) post-inclusion. Predictors of lumefantrine concentrations were analysed to show how both C [lum]day7 and the weight-adjusted lumefantrine dose affect 28-day recrudescence and re-infection risks. The implications of these novel findings are discussed in terms of the emergence of lumefantrine-resistant strains in Africa. RESULTS: C [lum]day3 and C [lum]day7 distributions among 241 supervised and 238 unsupervised patients were positively skewed. Unsupervised treatment and decreasing weight-adjusted lumefantrine dose were negatively associated with C [lum]day3. Unsupervised treatment and decreasing age showed strong negative associations with C [lum]day7. Both models were poorly predictive (R-squared < 0.25). There were no recrudescences in either arm, but decreasing lumefantrine dose per Kg resulted in up to 13-fold higher adjusted risks of re-infection. Re-infections occurred only among patients with C [lum]day7 below 400 ng/mL (p < 0.001). CONCLUSION: Maintaining the present six-dose regimen and ensuring high adherence and intake are essential to maximize the public health benefits of this valuable drug combination
Introductory remarks about the Volume II of the complete works of Gabrio Piola
No full textIn this Volume II of the translations into English of the works by Gabrio Piola, we begin from the true first work written by the young Gabrio before 1824, when he was less than 30 years old. The content of the work Sull’applicazione de’ principj della meccanica analitica del Lagrange ai principali problemi. Memoria di Gabrio Piola presentata al concorso del premio e coronata dall’I.R. Istituto di Scienze, ecc. nella solennità del giorno 4 ottobre 1824, Milano, Imp. Regia stamperia, 1825, submitted to respond to a research program proposed by the I.R. Istituto on 4th October 1822, is in some aspects very modern and astonishingly topical
The Loss and Recovery of the Works by Piola and the Italian Tradition of Mechanics
No full textIn this chapter, we look in detail at the aspects concerning the transmission of scientific knowledge of the Italian school of Continuum Mechanics, mainly headed by Gabrio Piola, which strongly supported the point of view of Archytas of Tarentum as rediscovered by D’Alembert and Lagrange. The process of systematically removing references to the name of Gabrio Piola in Continuum Mechanics (and part of his results) is just one of many examples of how some social groups have, over the centuries and in different cultural fields, rewritten more or less relevant parts of the cultural knowledge of a society. Specifically, Gabrio Piola’s contribution to mechanical sciences has been greatly underestimated in both the more theoretical mathematical-physics literature and in the more applied and engineering oriented one. We remark, in the discussion presented in this Chapter, that at the basis of this phenomenon one can always find common features as a sectarian vision of cultural progress or the conviction that the point of view of the own social group is clearly superior to that of all the others
Gabrio Piola and balance equations
No full textThe origin of modern continuum mechanics dates back to Cauchy [1] [8] and Poisson [9, 10], who investigated linear elastic solids and fluids subject to infinitesimal displacements. This is stated in the well known monographs on history of mechanics by Todhunter and Pearson [11], Dugas [12], Timoshenko [13], Benvenuto [14] . We find some more hints on the origins of the theory of elasticity also in the recent contributions by Capecchi et al. [15, 16, 17]. Cauchy and Poisson imagined natural bodies as constituted by very small particles of matter interacting by central forces. However, they derived continuum field equations by suitable analytical tricks, and eventually Cauchy adopted only continuous functions to describe the regions of ambient space filled by a huge number of particles very close to each other. Since then, continuum mechanics has influenced all basic studies on theoretical and applied mechanics, enlarging both its scopes and range of applications: electro-magnetism and heat/work are only two of them. Examples of continuum mechanics in these fields are provided by the pioneering works by Green [18] and Thomson [19, 20]; comprehensive expositions are the well known ones by Truesdell and Toupin [21] and Truesdell and Noll [22]; a more recent handbook is that by Gurtin et al. [23]. Structured continua, originated by the Cosserats [24, 25], represent another branch of continuum models and their study has lead to an established theory, see Capriz [26] for instance. Indeed, continua with (micro-)structure are optimal models for many objects in multiple fields of application: they may describe non-standard beams [27, 28], damaged structural elements [29], masonry [30, 31, 32], plasticity [33]. In addition, they may provide suitable frameworks for multi- field physics, such as piezoelectricity or the mechanics of mixtures or porous media: the various physical quantities entering the phenomena are seen simply as additional degrees of freedom in a generalized lagrangean system. Gabrio Piola (1794 1850) stood out among the Italian scholars in mechanics in the first half of 1800, though he was never in charge of a university chair. In a series of papers, published in Italian in some journals of almost no di diffusion outside Italy [34] [38], he was perhaps the first to present: a) a clear separation among kinematics, expressed by suitable constraint equations, and balance, expressed by Lagrange's virtual work [39], according to which inner actions are simply mechanical duals of suitable constraint equations; b) a clear statement that physical considerations on the constitution of inner actions lie beyond the position of kinematics and balance and are independent of them; c) an imaginary ideal state for any body, made up of a perfectly regular array of molecules, free of any stress; d) an imaginary intermediate con guration between the natural and the actual ones, so that constraint equations exist; and e) the possibility to obtain balance equations by considering a change in observer for the present con guration. These key points in Piola's principles of mechanics are put into evidence by Hellinger [41], and described with some depth in other studies on Piola's works [40, 47]. The aim of this work is, however, to stress the above said points, that seem quite original and basic for a more general theory of continua with respect to that by Cauchy, Poisson and their successors (among them Lamé [42] and Saint-Venant [43, 44]), well before the Cosserats', and with a very modern spirit.....
Irreducible representation of surface distributions and Piola transformation of external loads sustainable by third gradient continua
No full textIn this paper Piola transformations are found that relate the Eulerian and Lagrangian external loads which third gradient continua can sustain. As shown by Gabrio Piola and Paul Germain, the most effective postulation scheme in mechanics is based on the principle of virtual work and therefore continuummechanics must be mathematically founded based on the theory of distributions and on differential geometry. Using the principle of virtual work, the set of admissible external loads sustainable by third gradient continua is seen to include: i) volume force density, ii) surface density of contact force, iii) surface density of contact double force, iv) surface density of contact triple force, v) line density of edge contact forces, vi) line density of contact edge double forces and vii) contact forces concentrated on wedge points. Following the nomenclature introduced by Paul Germain, forces are dual in virtual work of virtual displacements, surface and line double forces are dual of the derivatives of virtual displacements in the normal direction(s) of the surfaces and edges constituting the boundary of the continuum, and surface triple forces are dual of the second normal derivatives of virtual displacements. Volume and surface forces transform as in first gradient Cauchy continua. Moreover we find that: a) the virtual work expended by Eulerian surface triple force, when transformed into the Lagrangian description, must be represented as the work expended by all the kinds of external Lagrangian loads listed in i)-vii); b) Eulerian surface double force transforms into Lagrangian surface double force, surface contact force and edge contact line force; c) Eulerian edge contact line double force transforms into Lagrangian edge contact line double forces, edge line forces and point concentrated wedge forces; d) Eulerian edge and wedge contact line forces transforms into their Lagrangian counterpart only. The Piola transformation formulas deduced in this paper depend on the first, second and third gradients of placement. The presented results allow for the formulation of well-posed boundary condition problems for third gradient continua in the Lagrangian description, and are relevant in computational mechanics. In view of the obtained Piola transformation formulas, the concept of dead loads needs to be modified. We believe to have given an example of how the Mechanics in the French Style, as developed on the ideas by D'Alembert and Lagrange, is still a fertile tool of invention
Subtropical Shelf Front cruise - Thermosalinograph data
No full textThis dataset contains the near-surface ocean (nominally 3 m depth) temperature and salinity observations collected during the Subtropical Shelf Front Cruise (PD_2013_04) carried out on board the research Vessel Puerto Deseado from 3 to 10 October 2013.
A SeaBird Electronics SBE 21 thermosalinograph, which recorded data every 30 seconds, was used throughout the cruise. Data records in physical units are reported in an ascii text file. The variables are presented in the following order, with missing values indicated by "-9.990e-29":
Julian Day
Latitude [deg]
Longitude [deg]
Pressure [dbar]
Temperature [ITS-90, deg C]
Conductivity [S/m]
Salinity, Practical [PSU]
Sigma-t [kg/m^3]
Data were calibrated and quality controlled at the Servicio de HidrografÃa Naval, Argentina ([email protected]).
A readme.txt file containing this description is also included
Transformations for Piola-mapped elements
No full textThe Arnold–Winther element successfully discretizes the Hellinger–Reissner variational formulation of linear elasticity; its development was one of the key early breakthroughs of the finite element exterior calculus. Despite its great utility, it is not available in standard finite element software, because its degrees of freedom are not preserved under the standard Piola push-forward. In this work we apply the novel transformation theory recently developed by Kirby [SMAI J. Comput. Math., 4:197–224, 2018] to devise the correct map for transforming the basis on a reference cell to a generic physical triangle. This enables the use of the Arnold–Winther elements, both conforming and nonconforming, in the widely-used Firedrake finite element software, composing with its advanced symbolic code generation and geometric multigrid functionality. Similar results also enable the correct transformation of the Mardal–Tai–Winther element for incompressible fluid flow. We present numerical results for both elements, verifying the correctness of our theory
A novel pulsatile platform for the ex-vivo evaluation of early remodelling events in human saphenous veins
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