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Publications

2025

SIMD Acceleration of Matrix-Vector Operations on RISC-V for Variable Precision Neural Networks

Authors
Salinas, G; Sequeira, G; Rodriguez, A; Bispo, J; Paulino, N;

Publication
2025 IEEE INTERNATIONAL PARALLEL AND DISTRIBUTED PROCESSING SYMPOSIUM WORKSHOPS, IPDPSW

Abstract
The rapid proliferation of Edge AI applications demands efficient, low-power computing architectures tailored to specific workloads. The RISC-V ecosystem is a promising solution, and has led to a fast growth of implementations based on custom instructions extensions, but with varying degrees of functionality and support which may hinder easy adoption. In this paper, we extensively review existing RISC-V extensions targeting primarily the AI domain and respective compilation flows, highlighting challenges in deployment, usability, and compatibility. We further implement and provide usable containerized environments for two of these works. To address the identified challenges, we then propose an approach for lightweight early validation of custom instructions via source-to-source transformations, without need of compiler modifications. We target our own Single Instruction Multiple Data (SIMD) accelerator, which we integrate into a CORE-V cv32e40px baseline core through custom instructions, and versus which we achieve up to 11.9x speedup for matrix-vector operations.

2025

The Robust Vehicle Routing Problem With Synchronization: Models and Branch-And-Cut Algorithms

Authors
Soares, R; Parragh, SN; Marques, A; Amorim, P;

Publication
NETWORKS

Abstract
The Vehicle Routing Problem with Synchronization (VRPSync) aims to minimise the total routing costs while considering synchronization requirements that must be fulfilled between tasks of different routes. These synchronization requirements are especially relevant when it is necessary to have tasks being performed by vehicles within given temporal offsets, a frequent requirement in applications where multiple vehicles, crews, materials, or other resources are involved in certain operations. Although several works in the literature have addressed this problem, mainly the deterministic version has been tackled so far. This paper presents a robust optimization approach for the VRPSync, taking into consideration the uncertainty in vehicle travel times between customers. This work builds on existing approaches in the literature to develop mathematical models for the Robust VRPSync, as well as a branch-and-cut algorithm to solve more difficult problem instances. A set of computational experiments is also devised and presented to obtain insights regarding key performance parameters of the mathematical models and the solution algorithm. The results suggest that solution strategies where certain standard problem constraints are only introduced if a candidate solution violates any of those constraints provide more consistent improvements than approaches that rely on tailor-made cutting planes, added through separation routines. Furthermore, the analysis of the Price of Robustness indicators shows that the adoption of robust solutions can have a significant increase in the total costs, however, this increase quickly plateaus as budgets of uncertainty increase.

2025

Charting a course at the human-AI frontier: a paradigm matrix informed by social sciences and humanities

Authors
Chaves, R; Barbosa, CE; de Oliveira, GA; Oliveira Lyra, AD; Argôlo, MM; Salazar, H; Lima, Y; Schneider, D; Correia, A; de Souza, JM;

Publication
AI Soc.

Abstract

2025

Keigo: Co-designing Log-Structured Merge Key-Value Stores with a Non-Volatile, Concurrency-aware Storage Hierarchy (Extended Version)

Authors
Adão, R; Wu, Z; Zhou, C; Balmau, O; Paulo, J; Macedo, R;

Publication
CoRR

Abstract

2025

Validation of Multi-Subject Whole-Body COM Dynamics Based on 3D Anatomical Kinematics

Authors
Rodrigues, C; Correia, M; Abrantes, J; Rodrigues, M; Nadal, J;

Publication
IEEE Portuguese Meeting on Bioengineering, ENBENG

Abstract
This study presents and applies validation of whole-body (WB) center of mass (COM) dynamics during impulse phase of explosive maximum vertical jumps (MVJ) using a low-cost image system and 3D anatomical kinematics based on direct linear transformation of 2D image. Root mean square error (RMSE) and squared error analysis led to detection of specific behavior at different MVJ impulse phases with application on kinematic validation of WB COM displacement from dynamics, coping with the limitations of the time flight method and WB weight for vertical impulse and contributing for accurate assessment of lower limb muscle force. © 2025 IEEE.

2025

A Domain-Agnostic Virtual Choreography Framework for Digital Twins: an Oil Spill application

Authors
Cassola, F; Cavaleiro, V; Lacet, D; Correia, M; Oliveira, MA; de Carvalho, AV; Morgado, L;

Publication
OCEANS 2025 BREST

Abstract
Digital Twins (DTs) for the ocean are rapidly emerging as essential tools for understanding, forecasting, and managing environmental phenomena. However, most existing DT visualization solutions are tightly coupled to specific platforms and lack semantic coherence and interoperability-challenges that are particularly critical in federated and distributed DT systems. Furthermore, visualizing dynamic and spatio-temporal behaviors, such as oil spills, across multiple rendering environments remains a complex, platform-dependent task. In this paper, we present VChor, a domain-agnostic virtual choreography framework designed to address these limitations. Our approach integrates model-driven engineering, semantic web technologies, and platform-independent representations to support the declarative specification of behaviors and visual mappings. A single VChor instance describes spatio-temporal dynamics and associated actions, and can be interpreted by multiple visualization engines (e.g., Unity3D and CesiumJS) without the need for code recompilation or platform-specific programming. We demonstrate our approach through a real-world oil spill monitoring use case, developed in the context of the ILIAD H2020 project, and encapsulated within a modular Application Package. This package automates the generation, validation, and transformation of virtual choreographies from raw data to platform-specific outputs. The framework promotes interoperability, reusability, and scalability, while supporting FAIR principles in environmental Digital Twin workflows. The findings highlight VChor's potential to streamline scenario modeling, enable cross-platform visualization, and support decision-makers with accurate, flexible, and reusable visual representations of ocean dynamics.

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