702 research outputs found
Le Illustrazioni dei Papiri ercolanesi di Angelo Antonio Scotti
The Accademico Ercolanese Angelo Antonio Scotti, who edited five Herculaneum papyri in volumes IV, VI e XI of the so-called Collectio Prior (Herculanensium Voluminum quae supersunt), also made the partial Illustrazioni (transcripts) of other papyri, which have not been published and are preserved in the Archivio dell'Officina dei Papiri Ercolanes
Reducing the View Selection Problem through Code Modeling: Static and Dynamic approaches
2015 - 2016Data warehouse systems aim to support decision making by providing users with the appropriate information at the right time. This task is particularly challenging in business contexts where large
amount of data is produced at a high speed. To this end, data warehouses have been equipped with
Online Analytical Processing tools that help users to make fast and precise decisions througt the
execution of complex queries. Since the computation of these queries is time consuming, data
warehouses precompute a set of materialized views answering to the workload queries.
This thesis work defines a process to determine the minimal set of workload queries and the set of views to materialize. The set of queries is represented by an optimized lattice structure used to select the views to be materialized according to the processing time costs and the view storage space.
The minimal set of required Online Analytical Processing queries is computer by analyzing the data
model defined with the visual language CoDe (Complexity Design). The latter allows to conceptually
organizatio the visualization of data reports and to generate visualizations of data obtained from data-‐mart queries. CoDe adopts a hybrid modeling process combining two main methodologieser-‐driven and data- driven. The first aims to create a model according to the user knowledge, re-quirements, and analysis needs, whilst the latter has in charge to concretize data and their relationships in the model through Online Analytical Processing queries. Since the materialized views change over time, we also propose a dynamic process that allows users to upgrade the CoDe model with a context-‐aware editor, build an optimized lattice structure able to
minimize the effort to recalculate it,and propose the new set of views to materialize Moreover, the process applies a Markov strategy to predict whether the views need to be recalculate or not according to the changes of the model. The effectiveness of the proposed techniques has been evaluated on a real world data warehouse. The results revealed that the Markov strategy gives a better set of solutions in term of storage space and total processing cost. [edited by author]
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Self-Assembled Ruthenium(II)Porphyrin-Aluminium(III)Porphyrin-Fullerene Triad for Long-Lived Photoinduced Charge Separation
A very efficient metal-mediated strategy led, in a single step, to a quantitative construction of a new three-component
multichromophoric system containing one fullerene monoadduct, one aluminium(III) monopyridylporphyrin, and one
ruthenium(II) tetraphenylporphyrin. The Al(III) monopyridylporphyrin component plays the pivotal role in directing the correct
self-assembly process and behaves as the antenna unit for the photoinduced processes of interest. A detailed study of the
photophysical behavior of the triad was carried out in different solvents (CH2Cl2, THF, and toluene) by stationary and timeresolved
emission and absorption spectroscopy in the pico- and nanosecond time domains. Following excitation of the Alporphyrin,
the strong fluorescence typical of this unit was strongly quenched. The time-resolved absorption experiments
provided evidence for the occurrence of stepwise photoinduced electron and hole transfer processes, leading to a chargeseparated
state with reduced fullerene acceptor and oxidized ruthenium porphyrin donor. The time constant values
measured in CH2Cl2 for the formation of charge-separated state Ru-Al+-C60 - (10 ps), the charge shift process (Ru-Al+-C60
- \u2192 Ru+-Al-C60 -), where a hole is transferred from Al-based to Ru-based unit (75 ps), and the charge recombination
process to ground state (>5 ns), can be rationalized within the Marcus theory. Although the charge-separating
performance of this triad is not outstanding, this study demonstrates that, using the self-assembling strategy, improvements
can be obtained by appropriate chemical modifications of the individual molecular components
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