1,721,196 research outputs found
Lauro G. Caloca, Dengri y otras personas posando en los patios de Palacio Nacional, retrato de grupo.
No full textLAURO G. CALOCA DENEGRI, I.O
Elucidating the Relative and Absolute Configuration of Organic Compounds by Quantum Mechanical Approaches
No full textDifferent examples of the application of quantum mechanical (QM) methods combined with experimental approaches, such as NMR spectroscopy and electronic circular dichroism (ECD), are reported to highlight their successful application in the determination of the stereochemical arrangement of organic compounds. A first part is dedicated to various examples and methodological studies based on the comparison of experimental NMR parameters (13C and 1H NMR chemical shifts, homonuclear and heteronuclear J coupling constants) and their related values calculated at the QM theory level, with particular applications in the assignment of the relative configuration of organic compounds. A final section is focused on the determination of the absolute configuration by the comparison of experimental and predicted NMR parameters and ECD spectra
VALUTAZIONE PRESTAZIONALE SOTTO SISMA DI UN EDIFICIO IN MURATURA E C.A. RINFORZATO MEDIANTE FRP
No full textSono state valutate le prestazioni sismiche di un edificio in muratura e c.a. rinforzato mediante l’impiego di materiali polimerici fibrorinforzati. A tale scopo, è stata in primo luogo effettuata la calibrazione del modello agli elementi finiti a partire dalle proprietà dinamiche valutate sperimentalmente. É stata quindi condotta un’analisi adattiva di pushover che consente di variare la distribuzione delle spinte in presenza di plasticizzazioni non uniformi. A tale scopo è stato impiegato un modello omogeneo e isotropo a fessurazione diffusa. La risposta inelastica complessiva è stata valutata con un approccio agli spostamenti, mettendo a punto una procedura incrementale ma non iterativa che rappresenta una versione adattiva del metodo dello spettro di capacità e degli spettri di risposta inelastici. La procedura è stata validata attraverso il confronto con i risultati delle prove su tavola vibrante condotte su un modello in scala ridotta. L’obiettivo finale del lavoro è quello di valutare gli effetti degli interventi di rinforzo sulla sicurezza della struttura muraria nei confronti non solo del collasso, ma anche degli altri stati limite.
In this paper the performance-based assessment of a masonry building strengthened with fibre reinforced polymers to improve seismic resistance is carried out. At first, a specific procedure was used to calibrate the finite element model according to the experimental dynamic properties. Then, pushover analysis was carried out with an adaptive load pattern which allows for the redistribution of load as an effect of non-uniform yielding. A homogenous and isotropic smeared cracked model was used for non linear modelling of masonry. An incremental non-iterative procedure, that is an adaptive extension of the capacity spectrum and the inelastic demand response spectra method, was used for the displacement-based seismic assessment of the building. The proposed procedure was validated by comparison with the results from seismic response testing on a scale model. The final objective of the paper is the assessment of the effectiveness of retrofit as far as the safety not only at collapse but also at the other limit states
Valutazione prestazionale di edifici in muratura in presenza di interventi di miglioramento sismico
No full textIn this paper the performance-based assessment of a masonry building strengthened with fibre reinforced polymers to improve seismic resistance is carried out. At this aim, a nonlinear static procedure was used to estimate maximum lateral displacement, to control the acceptance criteria of unreinforced masonry walls and to keep them within tolerable limits at each performance level. These multi-level objectives were pursued with a procedure based on the adaptive pushover, the Capacity Spectrum Method and the Inelastic Demand Response Spectra. At first, a procedure based on the minimum error condition on the natural frequencies, mode shapes and modal forces was used to calibrate the finite element model. Then pushover analysis was carried out with an adaptive load pattern which allows for the redistribution of load as an effect of non-uniform yielding. An incremental non iterative procedure to correlate the earthquake intensity levels and performance levels defined by the acceptance criteria was used. Finally, the correlation between earthquake intensity levels and performance levels both for unreinforced and for the FRP strengthened masonry building was investigated
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
Le prime industrie litiche italiane
No full textViene illustrata l'emergere dell'attività di scheggiatura in Itali
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