In this paper we propose a query expansion and user profile enrichment approach to improve the performance of recommender
systems operating on a folksonomy, storing and classifying the tags used to label a set of available resources. Our approach
builds and maintains a profile for each user. When he submits a query (consisting of a set of tags) on this folksonomy to
retrieve a set of resources of his interest, it automatically finds further “authoritative” tags to enrich his query and proposes
them to him. All “authoritative” tags considered interesting by the user are exploited to refine his query and, along with
those tags directly specified by him, are stored in his profile in such a way to enrich it. The expansion of user queries
and the enrichment of user profiles allow any content-based recommender system operating on the folksonomy to retrieve and
suggest a high number of resources matching with user needs and desires. Moreover, enriched user profiles can guide any collaborative
filtering recommender system to proactively discover and suggest to a user many resources relevant to him, even if he has
not explicitly searched for them. 相似文献
This paper presents a novel approach for the integration of a set of eXtensible Markup Language (XML) Schemas. The proposed approach is specialized for XML, almost automatic, semantic and “light”. Further, an original peculiarity is that it is parametric w.r.t. a “severity” level against which the integration task is performed. The paper describes the approach in all details, illustrates various theoretical results, presents the experiments we have performed for testing it and, finally, compares it with various related approaches already proposed in the literature. 相似文献
Nowadays two main approaches are being pursued to reduce energy consumption of networks: the use of sleep modes in which devices enter a low-power state during inactivity periods, and the adoption of energy proportional mechanisms where the device architecture is designed to make energy consumption proportional to the actual load. Common to all the proposals is the evaluation of energy saving performance by means of simulation or experimental evidence, which typically consider a limited set of benchmarking scenarios. 相似文献
A modeling method aimed at eliminating the need of explicit crack representation in bi-dimensional structures is presented
for the simulation of the initiation and subsequent propagation within composite materials. This is achieved by combining
a meshless method with a physical stress–displacement based criterion known as Cohesive Model. This model consents to apply
a penalty-based approach to delamination modeling where a variable penalty factor along the crack segment allows to loosen
or tight the two parts according to their relative displacements. Results are showed for classical single mode loading benchmark
cases and compared to experimental results taken from the literature. 相似文献
In recent years, researchers have begun to study inductive databases, a new generation of databases for leveraging decision support applications. In this context, the user interacts with the
DBMS using advanced, constraint-based languages for data mining where constraints have been specifically introduced to increase
the relevance of the results and, at the same time, to reduce its volume. In this paper we study the problem of mining frequent
itemsets using an inductive database. We propose a technique for query answering which consists in rewriting the query in
terms of union and intersection of the result sets of other queries, previously executed and materialized. Unfortunately,
the exploitation of past queries is not always applicable. We then present sufficient conditions for the optimization to apply
and show that these conditions are strictly connected with the presence of functional dependencies between the attributes
involved in the queries. We show some experiments on an initial prototype of an optimizer which demonstrates that this approach
to query answering is viable and in many practical cases it drastically reduces the query execution time. 相似文献
This paper illustrates the development of an analytical model for a communication network providing integrated services to a population of mobile users, and presents performance results to both validate the analytical approach, and assess the quality of the services offered to the end users. The analytical model is based on continuoustime multidimensional birth–death processes, and is focused on just one of the cells in the network. The cellular system is assumed to provide three classes of service: the basic voice service, a data service with bit rate higher than the voice service, and a multimedia service with one voice and one data component. In order to improve the overall network performance, some channels can be reserved to handovers, and multimedia calls that cannot complete a handover are decoupled, by transferring to the target cell only the voice component and suspending the data connection until a sufficient number of channels become free. Numerical results demonstrate the accuracy of the approximate model, as well as the effectiveness of the newly proposed multimedia call decoupling approach. 相似文献
An integrated approach to quality of service for content delivery using Web services includes quality definitions, user contracts, and fault monitoring. 相似文献
The potential hazards resulting from a low-velocity impact (bird-strike, tool drop, runway debris, etc.) on aircraft structures, such as engine nacelle or a leading edge, has been a long-term concern to the aircraft industry. Certification authorities require that exposed aircraft components must be tested to prove their capability to withstand low-velocity impact without suffering critical damage.
This paper describes the results from experimental and numerical simulation studies on the impact and penetration damage of a sandwich panel by a solid, round-shaped impactor. The main aim was to prove that a correct mathematical model can yield significant information for the designer to understand the mechanism involved in the low-velocity impact event, prior to conducting tests, and therefore to design an impact-resistant aircraft structure.
Part of this work presented is focused on the recent progress on the materials modelling and numerical simulation of low-velocity impact response onto a composite aircraft sandwich panel. It is based on the application of explicit finite element (FE) analysis codes to study aircraft sandwich structures behaviour under low-velocity impact conditions. Good agreement was obtained between numerical and experimental results, in particular, the numerical simulation was able to predict impact damage and impact energy absorbed by the structure. 相似文献