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Publications

2022

A Flexible HLS Hoeffding Tree Implementation for Runtime Learning on FPGA

Authors
Sousa, LM; Paulino, N; Ferreira, JC; Bispo, J;

Publication
2022 IEEE 21ST MEDITERRANEAN ELECTROTECHNICAL CONFERENCE (IEEE MELECON 2022)

Abstract
Decision trees are often preferred when implementing Machine Learning in embedded systems for their simplicity and scalability. Hoeffding Trees are a type of Decision Trees that take advantage of the Hoeffding Bound to allow them to learn patterns in data without having to continuously store the data samples for future reprocessing. This makes them especially suitable for deployment on embedded devices. In this work we highlight the features of a HLS implementation of the Hoeffding Tree. The implementation parameters include the feature size of the samples (D), the number of output classes (K), and the maximum number of nodes to which the tree is allowed to grow (Nd). We target a Xilinx MPSoC ZCU102, and evaluate: the design's resource requirements and clock frequency for different numbers of classes and feature size, the execution time on several synthetic datasets of varying sizes (N) and the execution time and accuracy for two datasets from UCI. For a problem size of D=3, K=5, and N=40000, a single decision tree operating at 103MHz is capable of 8.3x faster inference than the 1.2 GHz ARM Cortex-A53 core. Compared to a reference implementation of the Hoeffding tree, we achieve comparable classification accuracy for the UCI datasets.

2022

ProGenVR: Natural Interactions for Procedural Content Generation in VR

Authors
Carvalho, B; Mendes, D; Coelho, A; Rodrigues, R;

Publication
ICAT-EGVE

Abstract

2022

What can move non-IS developers towards open and collaborative development initiatives?

Authors
Andrade, T; de Araujo, RM; Siqueira, SWM;

Publication
Braz. J. Inf. Syst.

Abstract

2022

Toward measuring supermassive black hole masses with interferometric observations of the dust continuum

Authors
Amorim, A; Bourdarot, G; Brandner, W; Cao, Y; Clénet, Y; Davies, R; De Zeeuw, PT; Dexter, J; Drescher, A; Eckart, A; Eisenhauer, F; Fabricius, M; Förster Schreiber, NM; Garcia, PJV; Genzel, R; Gillessen, S; Gratadour, D; Hönig, S; Kishimoto, M; Lacour, S; Lutz, D; Millour, F; Netzer, H; Ott, T; Paumard, T; Perraut, K; Perrin, G; Peterson, BM; Petrucci, PO; Pfuhl, O; Prieto, MA; Rouan, D; Santos, DJD; Shangguan, J; Shimizu, T; Sternberg, A; Straubmeier, C; Sturm, E; Tacconi, LJ; Tristram, KRW; Widmann, F; Woillez, J; GRAVITY, C;

Publication
ASTRONOMY & ASTROPHYSICS

Abstract
This work focuses on active galactic nuclei (AGNs) and on the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H beta BLR size, with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence simply be derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and they are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate a measuring of the BH mass based on the dust-continuum size with our first calibration of the R-BLR-R-d relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential of measuring BH masses for a large sample of AGNs in the low-redshift Universe.

2022

Towards novel deep neuroevolution models: chaotic levy grasshopper optimization for short-term wind speed forecasting

Authors
Jalali, SMJ; Ahmadian, S; Khodayar, M; Khosravi, A; Ghasemi, V; Shafie khah, M; Nahavandi, S; Catalao, JPS;

Publication
ENGINEERING WITH COMPUTERS

Abstract
High accurate wind speed forecasting plays an important role in ensuring the sustainability of wind power utilization. Although deep neural networks (DNNs) have been recently applied to wind time-series datasets, their maximum performance largely leans on their designed architecture. By the current state-of-the-art DNNs, their architectures are mainly configured in manual way, which is a time-consuming task. Thus, it is difficult and frustrating for regular users who do not have comprehensive experience in DNNs to design their optimal architectures to forecast problems of interest. This paper proposes a novel framework to optimize the hyperparameters and architecture of DNNs used for wind speed forecasting. Thus, we introduce a novel enhanced version of the grasshopper optimization algorithm called EGOA to optimize the deep long short-term memory (LSTM) neural network architecture, which optimally evolves four of its key hyperparameters. For designing the enhanced version of GOA, the chaotic theory and levy flight strategies are applied to make an efficient balance between the exploitation and exploration phases of the GOA. Moreover, the mutual information (MI) feature selection algorithm is utilized to select more correlated and effective historical wind speed time series features. The proposed model's performance is comprehensively evaluated on two datasets gathered from the wind stations located in the United States (US) for two forecasting horizons of the next 30-min and 1-h ahead. The experimental results reveal that the proposed model achieves the best forecasting performance compared to seven prominent classical and state-of-the-art forecasting algorithms.

2022

A realistic simulation environment as a teaching aid in educational robotics

Authors
Lima, J; Kalbermatter, RB; Braun, J; Brito, T; Berger, G; Costa, P;

Publication
2022 LATIN AMERICAN ROBOTICS SYMPOSIUM (LARS), 2022 BRAZILIAN SYMPOSIUM ON ROBOTICS (SBR), AND 2022 WORKSHOP ON ROBOTICS IN EDUCATION (WRE)

Abstract
The experimental component is an essential method in Engineering education. Sometimes the availability of laboratories and components is compromised, and the COVID19 pandemic worsened the situation. Resorting to an accurate simulation seems to help this process by allowing students to develop the work, program, test, and validate it. Moreover, it lowers the development time and cost of the prototyping stages of a robotics project. As a multidisciplinary area, robotics requires simulation environments with essential characteristics, such as dynamics, connection to hardware (embedded systems), and other applications. Thus, this paper presents the Simulation environment of SimTwo, emphasizing previous publications with models of sensors, actuators, and simulation scenes. The simulator can be used for free, and the source code is available to the community. Proposed scenes and examples can inspire the development of other simulation scenes to be used in electrical and mechanical Engineering projects.

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