1,721,001 research outputs found
An algorithm for the analysis of the dynamic of rotating electrical machines with ring and bar commutator windings
No full textImprovement of P.M. stepping motor performances by the modification of system parameters with active impedance
No full textAnalyzing the influence of graviton fluctuations on the inflationary spectrum with a Kuchař-Torre clock
Full text linkThis paper focuses on the search for a coherent and consistent formulation to describe quantum gravity corrections to quantum field theory. We implement two fundamental ingredients discussed in previous analyses: on one hand, the construction of the Wentzel-Kramer-Brillouin and Born-Oppenheimer picture for the Wheeler-DeWitt theory of gravity and matter by using a reference fluid as physical clock; on the other hand, we explicitly separate in the metric field its own purely classical contribution from the quantum graviton degrees of freedom. This allows to derive, by the expansion in a Planckian parameter, a unitary theory properly evaluating the quantum field theory modifications in the considered regime. More specifically, we recover at zero order the standard theory on curved space-time after averaging over the graviton sector. The physical corrections are induced at first order by (quantum) gravitons, thought as the slow-varying component of the system, as opposed to the fast quantum matter and reference fluid. The genuine contribution due to gravitons, nonfactorizable into an independent phase, provides a coherent quantum gravity modification on quantum field theory. We show this by determining the predicted inflationary spectrum during an exact de Sitter phase of the primordial Universe, finding a breaking of the scale invariant morphology even when the inflation potential is modeled by a cosmological constant term. Remarkably, the behavior of such non-scale-invariant spectrum overlaps predictions previously obtained in literature by neglecting nonunitary terms emerging in those formulations. In this respect, the present model provides a satisfactory regularization of such approaches by virtue of a more realistic construction of the physical clock for the total (gravity+matter) quantum dynamics
Tecnica di modulazione della tensione per motori in C.A. alimentati da inverter con ampio campo di variazione della velocità
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Cinematic architectures INSITU: Notes on the participatory construction of a visual urban imagery
No full textThe chapter offers a close analysis of InSitu, an interactive film by Antoine Viviani composed by an assemblage of geolocalized “chapters” by different users. The piece is studied as an example of a renegotiation of urban imagery through database logics
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
Soil organic matter properties after 40 years of different use of organic and mineral fertilisers
No full textOrganic inputs can help maintain soil fertility by improving chemical and biological soil properties. The effects of 40 years of
organic, mineral and mixed fertilisations on soil organic properties were evaluated in a continuous maize system. The following
properties were analysed: total organic carbon (TOC), humic carbon (HC) and its molecular weight distribution, HC/TOC and the
hormone—(auxin and gibberellin-like) activities of the humic substances and their effects on two key enzymes (nitrate reductase
(NR) and glutamine synthetase (GS)) involved in nitrate assimilation in maize seedlings.
Farmyard manure fertilisation sustained TOC in the top layers while mineral treatments alone or mixed with organic exhibited
a minor influence on the organic matter evolution: over 40 years the average TOC depletion was 23% with liquid manure and
mixed fertilisations, 43% with mineral fertilisers alone and 51% in the control.
The different treatments also influenced the HC molecular complexity. Farmyard fertilisations improved the production of
humus with a high degree of policondensation, a fraction usually linked to soil fertility; the absence of organic fertiliser inputs
determined the opposite, with a higher percentage of non-complex and light-weight humus.
The hormone-like and biochemical activities of humus substances were evident with the organic and mixed fertilisations. The
humus extracted by the soil treated with farmyard manure exhibited the best gibberellin-like activity and the highest increases
of NR (+42%) and GS (+49%) activities with respect to the control. The other treatments showed intermediate stimulations as
in the case of mixed fertilisations (NR + 22% and GS + 24%), or no activities as in the case of mineral inputs
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