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Publications

Publications by José Carlos Alves

1998

Flexible hardware acceleration for nesting problems

Authors
Ferreira, JC; Alves, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;

Publication
5th IEEE International Conference on Electronics, Circuits and Systems, ICECS 1998, Surfing the Waves of Science and Technology, Lisbon, Portugal, September 7-10, 1998

Abstract
The nesting (or placement) problem is an NP-hard combinatorial problem with important industrial applications, e.g. in apparel or footwear industry. This paper describes a hardware infrastructure to accelerate the processing of the underlying geometric information. The system consists of an FPGA-based reconfigurable platform enhanced by an ASIC for the processing of irregular polygons. The paper discusses the need for such a platform, establishes the main design guidelines and describes the architecture and modes of operation of both the reconfigurable infrastructure and the dedicated IC.

1999

FAFNER-Accelerating Nesting Problems with FPGAs

Authors
Alves, JC; Ferreira, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;

Publication
7th IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM '99), 21-23 April 1999, Napa, CA, USA

Abstract
The nesting problem consists of defining the cutting plan of a piece of raw material in smaller irregular shapes, and has applications in the apparel and footwear industries. Due to its NP-hard nature, the optimal solution can only be guaranteed by exhaustively trying all possible solutions and choosing the best one. Because this is impractical in real-life industrial problems, automatic approaches are based on optimization meta-heuristics that search for sub-optimal but good enough solutions. These optimization techniques rely on the construction and evaluation of several solutions, thus requiring heavy geometric manipulation of the irregular polygons that constitute the problem data. Efficient processing of this geometric information is thus necessary to make effective fully automatic approaches to nesting problems in industrial environments. This paper describes Fafner, an FPGA-based custom computing machine that is used to accelerate the geometric operations, that are in the core of heuristic solutions to the nesting problem. The system is used as an auxiliary processor attached to a low cost personal computer, and combines a custom programmable processor with an array of custom circuits for the processing of irregular polygons.

1997

A vector architecture for higher-order moments estimation

Authors
Alves, JC; Puga, A; CorteReal, L; Matos, JS;

Publication
1997 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING, VOLS I - V: VOL I: PLENARY, EXPERT SUMMARIES, SPECIAL, AUDIO, UNDERWATER ACOUSTICS, VLSI; VOL II: SPEECH PROCESSING; VOL III: SPEECH PROCESSING, DIGITAL SIGNAL PROCESSING; VOL IV: MULTIDIMENSIONAL SIGNAL PROCESSING, NEURAL NETWORKS - VOL V: STATISTICAL SIGNAL AND ARRAY PROCESSING, APPLICATIONS

Abstract
Higher-order statistics extend the analysis methods of non-linear systems and non-gaussian signals based on the autocorrelation and power spectrum. The main drawback of their use in real time applications is the high complexity of their estimation due to the large number of arithmetic operations. This paper presents an experimental vector architecture for the estimation of the higher-order moments. The processor's core is a pipelined multiply-accumulate unit that receives four data vectors and computes in parallel the moment taps up to the fourth-order. The design of custom cache memory organization and address generation circuits has led to more than 11 operations per clock cycle. The architecture was modeled and simulated in Verilog and is presently being implemented in XILINX field-programmable gate arrays (FPGAs) and one custom integrated circuit for the multiply-accumulate unit.

1998

RVC - A reconfigurable coprocessor for vector processing applications

Authors
Alves, JC; Matos, JS;

Publication
IEEE SYMPOSIUM ON FPGAS FOR CUSTOM COMPUTING MACHINES, PROCEEDINGS

Abstract
This work presents RVC (Reconfigurable Vector Coprocessor), a FPGA based custom computing machine for vector processing applications. This system was built to serve as an implementation platform for a custom vector processor designed for a digital signal processing application. Although its architecture has been in part dictated by the immediate needs of that dedicated processor, it also serves for other custom machines exhibiting similar requirements of vector processing. © 1998 IEEE.

1996

A simulated annealing approach for high-level synthesis with reconfigurable functional units

Authors
Alves, JC; Matos, JS;

Publication
38TH MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, PROCEEDINGS, VOLS 1 AND 2

Abstract
In this paper, we present an application of the simulation annealing optimization algorithm to the problem of high-level synthesis of digital systems, targeted to architectures with run-time reconfigurable functional units. The scheduling, allocation and binding problems are treated simultaneously. Reconfiguration times and execution delays are taken into account, along with pipelined execution and precise clock cycles for consumption of each operand.

1997

Implementation and evaluation of mixed current / voltage testing using the IEEE P1149.4 infrastructure

Authors
Da Silva, JM; Alves, JC; Matos, JS;

Publication
IEE Colloquium (Digest)

Abstract
This paper presents experiments carried out with a prototype test chip provided by the IEEE P1149.4 Mixed-Signal Testing Working Group, which explore the architecture of the proposed analogue boundary module to implement simultaneous observation of power supply current and output voltage, towards mixed current/voltage testing of analogue and mixed-signal circuits.

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