2015
Autores
Paulino, N; Ferreira, JC; Cardoso, JMP;
Publicação
ACM TRANSACTIONS ON RECONFIGURABLE TECHNOLOGY AND SYSTEMS
Abstract
This article presents a reconfigurable hardware/software architecture for binary acceleration of embedded applications. A Reconfigurable Processing Unit (RPU) is used as a coprocessor of the General Purpose Processor (GPP) to accelerate the execution of repetitive instruction sequences called Megablocks. A toolchain detects Megablocks from instruction traces and generates customized RPU implementations. The implementation of Megablocks with memory accesses uses a memory-sharing mechanism to support concurrent accesses to the entire address space of the GPP's data memory. The scheduling of load/store operations and memory access handling have been optimized to minimize the latency introduced by memory accesses. The system is able to dynamically switch the execution between the GPP and the RPU when executing the original binaries of the input application. Our proof-of-concept prototype achieved geometric mean speedups of 1.60x and 1.18x for, respectively, a set of 37 benchmarks and a subset considering the 9 most complex benchmarks. With respect to a previous version of our approach, we achieved geometric mean speedup improvements from 1.22 to 1.53 for the 10 benchmarks previously used.
2015
Autores
Teixeira, F; Campos, R; Ricardo, M;
Publicação
WUWNet
Abstract
The demand for broadband underwater communications is being pushed by the increasing use of Autonomous Underwater Vehicles (AUV) in underwater missions. IEEE 802.11, already used in AUV for above water communications, can also be employed underwater to enable cost-effective, high bandwidth, short range communications. However, the high RF attenuation underwater induces high variations of received power, which may affect the performance of existing rate adaptation algorithms designed for over-the-air networks. This paper evaluates the most relevant state-of-the-art IEEE 802.11 rate adaptation algorithms in underwater environment. Simulation results show the AARF algorithm outperforms the widely used Minstrel algorithm, as well as the CARA, RRAA and ONOE algorithms.
2015
Autores
Branco, F; Gonçalves, R; Martins, J; Cota, MP;
Publicação
NEW CONTRIBUTIONS IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 1, PT 1
Abstract
The agri-food organizations evolution, and its inherent need for well supported decision making, has led to an increase on the integration of IT/IS into their business and operational processes. With this in mind, an analysis was performed to the use of systems designed to support business decisions, thus allowing to acknowledge that there was none that answered to the needs inherent to organization from the mushroom production sector. This led to the definition and implementation of a DSS system, with the necessary features and qualities, which would help the mentioned activity sector needs. This DSS was designed and tested in a real environment through the implementation of a case study within a eatable mushrooms production company named "Sousacamp Group". With the implementation of the proposed DSS, the referred business group has reported an increased in their performance levels and decision making accuracy.
2015
Autores
Morgado, ML; Morgado, LF; Silva, N; Morais, R;
Publicação
INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS
Abstract
In this paper the first steps for the derivation of a mathematical model to describe the mechanical behaviour of a cylindrical electromagnetic vibration energy harvester, designed to extract energy from human gait to power biomedical implantable devices, are provided. As it is usual, in the modelling of such devices, the proposed mechanical model is also based on the solution of Newton's second law, but here a nonlinear closed-form expression is used for the resulting magnetic force of the system, unlike what has been done in previous works where, traditionally, that expression is a linear or is a nonlinear approximation of the real one. The main feature of this mechanical model is that it depends on several parameters which are related to the main characteristics of this kind of devices, which constitutes a major advantage with respect to the usual models available in the literature since these characteristics can always be changed in order to optimize the device.
2015
Autores
Martins, P; Fernandes, JP; Saraiva, J;
Publicação
CENTRAL EUROPEAN FUNCTIONAL PROGRAMMING SCHOOL, CEFP 2013
Abstract
In this paper we present a methodology to implement multiple traversal algorithms in a functional programming setting. The implementations we obtain s of highly modular and intermediate structure free programs, that rely on the concept of functional zippers to navigate on data structures. Even though our methodology is developed and presented under Haskell, a lazy functional language, we do not make essential use of laziness. This is an essential difference with respect to other attribute grammar embeddings. This also means that an approach similar to ours can be followed in a strict functional setting such as Ocaml, for example. In the paper, our technique is applied to a significant number of problems that are well-known to the functional programming community, demonstrating its practical interest.
2015
Autores
Madeira, A; Martins, MA; Barbosa, LS; Hennicker, R;
Publicação
FORMAL ASPECTS OF COMPUTING
Abstract
Hybrid logics, which add to the modal description of transition structures the ability to refer to specific states, offer a generic framework to approach the specification and design of reconfigurable systems, i.e., systems with reconfiguration mechanisms governing the dynamic evolution of their execution configurations in response to both external stimuli or internal performance measures. A formal representation of such systems is through transition structures whose states correspond to the different configurations they may adopt. Therefore, each node is endowed with, for example, an algebra, or a first-order structure, to precisely characterise the semantics of the services provided in the corresponding configuration. This paper characterises equivalence and refinement for these sorts of models in a way which is independent of (or parametric on) whatever logic (propositional, equational, fuzzy, etc) is found appropriate to describe the local configurations. A Hennessy-Milner like theorem is proved for hybridised logics.
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