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Publications

2008

A Compiler Approach to Managing Storage and Memory Bandwidth in Configurable Architectures

Authors
Baradaran, N; Diniz, PC;

Publication
ACM TRANSACTIONS ON DESIGN AUTOMATION OF ELECTRONIC SYSTEMS

Abstract
Configurable architectures offer the unique opportunity of realizing hardware designs tailored to the specific data and computational patterns of an application code. Customizing the storage structures is becoming increasingly important in mitigating the continuing gap between memory latencies and internal computing speeds. In this article we describe and evaluate a compiler algorithm that maps the arrays of a loop-based computation to internal storage structures, either RAM blocks or discrete registers. Our objective is to minimize the overall execution time while considering the capacity and bandwidth constraints of the storage resources. The novelty of our approach lies in creating a single framework that combines high-level compiler techniques with lower-level scheduling information for mapping the data. We illustrate the benefits of our approach for a set of image/signal processing kernels using a Xilinx VirtexTM Field-Programmable Gate Array (FPGA). Our algorithm leads to faster designs compared to the state-of-the-art custom data layout mapping technique, in some instances using less storage. When compared to hand-coded designs, our results are comparable in terms of execution time and resources, but are derived in a minute fraction of the design time.

2008

The Mob core language and abstract machine (rev 0.2)

Authors
Paulino, Herve; Lopes, LuisM.B.;

Publication
CoRR

Abstract

2008

The semantics of MPEG-21 digital items revisited

Authors
Timmerer, C; Rogai, D; Andrade, MT; Carvalho, P; Cordara, G;

Publication
MM 2008 - Proceedings of the 2008 ACM International Conference on Multimedia, with Co-located Symposium and Workshops: MS 2008

Abstract
The MPEG-21 standard forms a comprehensive multimedia framework covering the entire multimedia distribution chain. In particular, it provides a flexible approach to represent, process, and transact complex multimedia objects which are referred to as Digital Items (DIs). DIs can be quite generic, independent of the application domain, and can encompass a diversity of media resources and metadata. This flexibility has an impact on the level of interoperability between systems and applications, since not all the functionality needs to be implemented. Furthermore, additional semantic rules may be implemented through the processing of the Digital Item which is possibly driven by proprietary metadata. This jeopardizes interoperability and consequently raises barriers to the successful achievement of augmented and transparent use of multimedia resources. In this context, we have investigated and evaluated the interoperability at the semantic level of Digital Items throughout the automated production, delivery and consumption of complex multimedia resources in heterogeneous environments. This paper describes the studies conducted, the experiments performed, and the conclusions reached towards that goal. © Copyright 2008 ACM.

2008

Learning from Data Streams: Synopsis and Change Detection

Authors
Sebastiao, R; Gama, J; Mendonca, T;

Publication
STAIRS 2008

Abstract
The aim of this PhD program is the study of algorithms for learning histograms, with the capacity of representing continuous high-speed flows of data and dealing with the current problem of change detection on data streams. In many modern applications, information is no longer gathered as finite stored data sets, but assuming the form of infinite data streams. As a large volume of information is produced at a high-speed rate it is no longer possible to use memory algorithms which require the full historic data stored in the main memory, so new ones are needed to process data online at the rate it is available. Moreover, the process generating data is not strictly stationary and evolves over time; so algorithms should, while extracting some sort of knowledge from this incessantly growing data, be able to adapt themselves to changes, maintaining a representation consistent with the most recent status of nature. In this work, we presented a feasible approach, using incremental histograms and monitoring data distributions, to detect concept drift in data stream context.

2008

Creative entrepreneurial abrasion in higher education

Authors
Pinto Ferreira, JJP; Sousa, M; Oliveira, J;

Publication
INNOVATION IN MANUFACTURING NETWORKS

Abstract
In a group setting, the exposure to different thinking styles and people promotes what is called creative abrasion, which, if properly managed, can greatly enhance the Innovation potential. This is the philosophy behind MIETE, which was conceived in 2004 to promote innovation and entrepreneurship with multidisciplinary teams. With this in mind, MIETE aims at adapting itself to the profiles of candidates from different areas including, amongst others, Management, Engineering, Biotechnology, Sciences and Design. In this paper the authors, report their experiences during the feedback sessions of the last two years with MIETE students, particularly in the 'Implementation and Strategies for Technology Comercialisation' workshops.

2008

Dual sensing of oxygen and temperature using quantum dots and a ruthenium complex

Authors
Jorge, PAS; Maule, C; Silva, AJ; Benrashid, R; Santos, JL; Farahi, F;

Publication
ANALYTICA CHIMICA ACTA

Abstract
A scheme for the simultaneous determination of oxygen and temperature using quantum dots and a ruthenium complex is demonstrated. The luminescent complex [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline)](2+) is immobilized in a non-hydrolytic sol-gel matrix and used as the oxygen sensor. The temperature information is provided by the luminescent emission of core-shell CdSe-ZnS semiconductor nanocrystals immobilized in the same material. Measurements of oxygen and temperature could be performed with associated errors of +/- 2% of oxygen concentration and +/- 1 degrees C, respectively In addition, it is shown that while the dye luminescence intensity is quenched both by oxygen and temperature, the nanocrystals luminescent emission responds only to temperature. Results presented demonstrate that the combined luminescence response allows the simultaneous assessment of both parameters using a single optical fiber system. In particular, it was shown that a 10% error in the measured oxygen concentration, induced by a change in the sample temperature, could be compensated using the nanocrystals temperature information and a correction function.

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