1,721,125 research outputs found
Apparatus for control and certification of the delivery of goods object of electronic commerce and for the concurrent control and certification of the execution of the related payment
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Future Video Delivery: Competition and coopetition between broadcasters, Telcos and Internet Players
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An Efficient Data Structure for Lattice Operations
No full textIn this paper, we consider the representation and management
of an element set on which a lattice partial order relation
is defined.
In particular, let
be the element set size, we present
an \nradn-space {\em implicit} data
structure for performing the
following set of basic operations:
\begin {itemize}
\item[1.] test the presence of an order relation between two given elements, in constant time;
\item[2.] find a path between two elements whenever one exists, in
steps, where
is the path length;
\item[3.] compute the successors and/or predecessors set of a given element,
in steps, where
is the size of the returned set;
\item[4.] given two elements, find all elements between them,
in time , where is the size of the returned set and
is the maximum indegree or outdegree in the transitive reduction of the
order relation;
\item[5.] given two elements, find the least common ancestor and/or the greatest common
successor in -time;
\item[6.] given elements, find the least common ancestor and/or the greatest common
successor in
\footnote{Unless stated otherwise, all logarithms are to the base 2.}-time.
\end {itemize}
The pre-processing time is
.
Focusing on the first operation, representing the building-box for all the others, we derive an overall
\nradn-spacetime bound which beats the order bottle-neck representing the present
complexity for this problem. Moreover, we will show that the complexity
bounds for the first three operations are optimal with
respect to the worst case. Additionally, a stronger result can be
derived. In particular, it is possible to represent a lattice in space
, where is the minimum number of disjoint chains which
partition the element set
Innovative thermoeconomic diagnosis of multiple faults in air conditioning units: Methodological improvements and increased reliability of results
No full textThermoeconomic faults diagnosis of air conditioning units is a pioneeristic approach to detect single or multiple faults and quantify their impact in terms of additional energy consumption. The poor reliability of conventional thermoeconomic approaches has been
limiting the interest for practical applications of this technique. In this paper an improved thermoeconomic diagnosis is proposed and applied to a reference 120 kWc air-cooled air
conditioning system; a simulator is used to evaluate thermodynamic data under normal and faulty conditions. Four faults are individually or simultaneously imposed: fouling at
condenser and evaporator, refrigerant undercharge and compressor valve leakage. For setting up the diagnostic tool only a few numerical or experimental tests are required; the
results testify the procedure to be sufficiently reliable both when heavy or light faults are considered. Also, the performance of the diagnostic procedure slightly improves when the
effects of “system level” faults like refrigerant undercharge are preliminarily filtered
The Italian electronic identity card: Overall architecture and IT infrastructure
No full textIn this paper we describe the overall process of deployment of the Italian Electronic Identity Card: the way it is issued, services it is used for, organizations involved in the process, and the Information Technology (IT) infrastructure enabling the effective management of the whole process while ensuring the mandatory security functions. Organizational complexity lies in the distribution of responsibilities for the management of Personal Data Registries (on which identity of people is based) which is an institutional duty of the more than 9000 Italian municipalities, and the need of keeping a centralized control on all processes dealing with identity of people as prescribed by laws and for national security and police purposes. Technical complexity stems from the need of efficiently supporting this distribution of responsibilities while ensuring. at the same time. interoperability of IT-based systems independent of technical choices of the organizations involved, and fulfilment of privacy constraints. The IT architecture defined for this purpose features a clear separation between security services, provided at an infrastructure level, and application services, exposed oil the Internet as Web Services. This approach has allowed to easily design and implement secure interoperability, since - notwithstanding the huge variety of IT solutions deployed all over the Italian Municipalities to manage Personal Data Registries - existing application services have not required major changes to be able to interoperate
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