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Publicações

2024

Using Source-to-Source to Target RISC-V Custom Extensions: UVE Case-Study

Autores
Henriques, M; Bispo, J; Paulino, N;

Publicação
PROCEEDINGS OF THE RAPIDO 2024 WORKSHOP, HIPEAC 2024

Abstract
Hardware specialization is seen as a promising venue for improving computing efficiency, with reconfigurable devices as excellent deployment platforms for application-specific architectures. One approach to hardware specialization is via the popular RISC-V, where Instruction Set Architecture (ISA) extensions for domains such as Edge Artifical Intelligence (AI) are already appearing. However, to use the custom instructions while maintaining a high (e.g., C/C++) abstraction level, the assembler and compiler must be modified. Alternatively, inline assembly can be manually introduced by a software developer with expert knowledge of the hardware modifications in the RISC-V core. In this paper, we consider a RISC-V core with a vectorization and streaming engine to support the Unlimited Vector Extension (UVE), and propose an approach to automatically transform annotated C loops into UVE compatible code, via automatic insertion of inline assembly. We rely on a source-to-source transformation tool, Clava, to perform sophisticated code analysis and transformations via scripts. We use pragmas to identify code sections amenable for vectorization and/or streaming, and use Clava to automatically insert inline UVE instructions, avoiding extensive modifications of existing compiler projects. We produce UVE binaries which are functionally correct, when compared to handwritten versions with inline assembly, and achieve equal and sometimes improved number of executed instructions, for a set of six benchmarks from the Polybench suite. These initial results are evidence towards that this kind of translation is feasible, and we consider that it is possible in future work to target more complex transformations or other ISA extensions, accelerating the adoption of hardware/software co-design flows for generic application cases.

2024

Optimisation for operational decision-making in a watershed system with interconnected dams

Autores
Vaz, TG; Oliveira, BB; Brandao, L;

Publicação
APPLIED ENERGY

Abstract
In the energy production sector, increasing the quantity and efficiency of renewable energies, such as hydropower plants, is crucial to mitigate climate change. This paper proposes a new and flexible model for optimising operational decisions in watershed systems with interconnected dams. We propose a systematic representation of watersheds by a network of different connection points, which is the basis for an efficient Mixed-Integer Linear Programming model. The model is designed to be adaptable to different connections between dams in both main and tributary rivers. It supports decisions on power generation, pumping and water discharge, maximising profit, and considering realistic constraints on water use and factors such as future energy prices and weather conditions. A relax-and-fix heuristic is proposed to solve the model, along with two heuristic variants to accommodate different watershed structures and sizes. Methodological tests with simulated instances validate their performance, with both variants achieving results within 1% of the optimal solution faster than the model for the tested instances. To evaluate the performance of the approaches in a real-world scenario, we analyse the case study of the C & aacute;vado watershed (Portugal), providing relevant insights for managing dam operations. The model generally follows the actual decisions made in typical situations and flood scenarios. However, in the case of droughts, it tends to be more conservative, saving water unless necessary or profitable. The model can be used in a decision-support system to provide decision-makers with an integrated view of the entire watershed and optimised solutions to the operational problem at hand.

2024

Open Design Communities: A bibliometric analysis of community-based management

Autores
Castro, H; Madureira, F; Vrabic, R; Avila, P; Simonnetto, E;

Publicação
Procedia Computer Science

Abstract
Online collaboration growing significantly in the development of open-source hardware and software has led to a surge of research interest. However, no comprehensive bibliometric review has investigated the management of digital communities in these ecosystems. In this study, academic contributions to the field of online community management in open-source hardware and software were mapped, highlighting influential research streams and trends. A bibliometric review was conducted based on a keyword search analysis of research databases (IEEExplore, Scopus, ScienceDirect, Web of Science), with a sample comprising an overall 399 papers. The study identifies the most impactful articles in the field, maps the diverse streams of research on online collaboration and community management, visualizes focus areas and trends, and pinpoints areas for further investigation. These findings will support future research within this rapidly evolving domain. © 2024 The Author(s). Published by Elsevier B.V.

2024

State Estimation Extensive Criticality Analysis Performed on Measuring Units: A Comparative Study

Autores
Nishio, A; Do Coutto, MB; de Souza, JCS; Pereira, J; Zanghi, E;

Publicação
JOURNAL OF CONTROL AUTOMATION AND ELECTRICAL SYSTEMS

Abstract
As one of the functions integrating energy management systems, state estimation (SE) is instrumental in monitoring power networks, allowing the best possible use of energy resources. It plays a decisive role in debugging if sufficient data are available, ruined if not. Criticality analysis (CA) integrates SE as a module in which elements of the estimation process-taken one-by-one or grouped (tuples of minimal multiple cardinality)-are designated essential. The combinatorial nature of extensive CA (ExtCA), derestricted from identifying only low-cardinality critical tuples, characterizes its computational complexity and imposes defiant limits in implementing it. This paper presents the methodology for ExtCA and compares algorithms to find an efficient solution for expanding the boundaries of this analysis problem. The algorithms used for comparison are one sequential Branch&Bound (a well-known paradigm for combinatorial optimization recently used in ExtCA) and two new parallels implemented on the central processing unit (CPU) and the graphics processing unit (GPU). The conceived parallel architecture favors evaluating massive combinations of diverse cardinality measuring unit (MU) tuples in ExtCA. The acronym MU refers to the aggregate of devices deployed at substations, such as a remote terminal unit, intelligent electronic device, and phasor measurement unit. The numerical results obtained in the paper show significant speed-ups with the novel parallel GPU algorithm, tested on different and real-scale power grids. Since, the visualization of the ExtCA results is still not a well-explored field, this work also presents a novel way of graphically depicting spots of weak observability using MU-oriented ExtCA.

2024

Preface

Autores
Zimmermann R.; Rodrigues J.C.; Simoes A.; Dalmarco G.;

Publicação
Springer Proceedings in Business and Economics

Abstract

2024

AOB: the new adaptive optics bench at Gemini North

Autores
Jouve, P; Correia, C; Fusco, T; Neichel, B; Rakich, A; Lawrence, J; Charton, J; Ching, T; Goodwing, M; Lamb, M; Sivo, G;

Publicação
ADAPTIVE OPTICS SYSTEMS IX

Abstract
AOB is an Adaptive Optics (AO) facility currently designed to feed the Gemini infrared Multi Object Spectrograph (GIRMOS) on the GEMINI North 8m class telescope located in Hawaii. This AO system will be made of two AO modes. A laser tomography AO (LTAO) mode using 4 LGS (laser guide stars) and [1-3] NGS (natural guide stars) for high performance over a narrow field of view (a few a rcsec). The LTAO reconstruction will benefit from the most recent developments in the field, such as the super-resolution concept for the multi-LGS tomographic system, the calibration and optimization of the system on the sky, etc. The system will also operate in Ground Layer Adaptive Optics (GLAO) mode providing a robust solution for homogeneous partial AO correction over a wide 2' FOV. This last mode will also be used as a first s tep of a MOAO (Multi-object adaptive optics) mode integrated in the GIRMOS instrument. Both GLAO and LTAO modes are optimized to provide the best possible sky coverage, up to 60% at the North Galactic Pole. Finally, the project has been designed from day one as a fast-track, cost effective project, aiming to provide a first scientific light on the telescope by 2028 at the latest, with a good balance of innovative and creative concepts combined with standard and well controlled components and solutions. In this paper, we will present the innovative concepts, design and performance analysis of the two AO modes (LTAO and GLAO) of the AOB project.

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