INESC-ID

About: INESC-ID is a nonprofit organization based out in Lisbon, Portugal. It is known for research contribution in the topics: Field-programmable gate array & Control theory. The organization has 932 authors who have published 2618 publications receiving 37658 citations.

A Tutorial on Multiplierless Design of FIR Filters: Algorithms and Architectures

Abstract: Finite impulse response (FIR) filtering is a ubiquitous operation in digital signal processing systems and is generally implemented in full custom circuits due to high-speed and low-power design requirements. The complexity of an FIR filter is dominated by the multiplication of a large number of filter coefficients by the filter input or its time-shifted versions. Over the years, many high-level synthesis algorithms and filter architectures have been introduced in order to design FIR filters efficiently. This article reviews how constant multiplications can be designed using shifts and adders/subtractors that are maximally shared through a high-level synthesis algorithm based on some optimization criteria. It also presents different forms of FIR filters, namely, direct, transposed, and hybrid and shows how constant multiplications in each filter form can be realized under a shift-adds architecture. More importantly, it explores the impact of the multiplierless realization of each filter form on area, delay, and power dissipation of both custom (ASIC) and reconfigurable (FPGA) circuits by carrying out experiments with different bitwidths of filter input, design libraries, reconfigurable target devices, and optimization criteria in high-level synthesis algorithms.

Caravela: A Novel Stream-Based Distributed Computing Environment

Abstract: Distributed computing implies sharing computation, data, and network resources around the world. The Caravela environment applies a proposed flow model for stream computing on graphics processing units that encapsulates a program to be executed in local or remote computers and directly collects the data through the memory or the network.

Designing Empathic Agents: Adults Versus Kids

Abstract: An evaluation study of a Virtual Learning Environment populated by synthetic characters for children to explore issues surrounding bullying behaviour is presented. This 225 participant evaluation was carried out with three stakeholder groups, (children, teachers and experts) to examine their attitudes and empathic styles about the characters and storyline believability. Results revealed that children expressed the most favourable views towards the characters and the highest levels of believability towards the bullying storyline. Children were more likely to have an empathic response than adults and found the synthetic characters more realistic and true-to-life.

An Exact Breadth-First Search Algorithm for the Multiple Constant Multiplications Problem

Abstract: This paper addresses the multiplication of one data sample with multiple constants using addition/subtraction and shift operations, i.e., the multiple constant multiplications (MCM) problem. The MCM problem finds itself and its variants in many applications, such as digital finite impulse response (FIR) filters, linear signal transforms, and computer arithmetic. Although many efficient algorithms have been proposed to implement the MCM using the fewest number of operations, due to the NP-hardness of the problem, they have been heuristics, i.e., they cannot guarantee the minimum solution. In this work, we propose an exact algorithm based on the breadth-first search that finds the minimum number of operations solution of mid-size MCM instances in a reasonable time. The proposed exact algorithm has been tested on a set of instances including FIR filter and randomly generated instances, and compared with the previously proposed efficient heuristics. It is observed from the experimental results that, even though the previously proposed heuristics obtain similar results with the minimum number of operations solutions, there are instances for which the exact algorithm finds better solutions than the prominent heuristics.

DIXI --- A Generic Text-to-Speech System for European Portuguese

Abstract: This paper describes a new generic text-to-speech synthesis system, developed in the scope of the Tecnovoz Project. Although it was primarily targeted at speech synthesis in European Portuguese, its modular architecture and flexible components allows its use for different languages. We also provide a survey on the development of the language resources needed by the TTS.