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Publicações

2023

Diagnosing applications' I/O behavior through system call observability

Autores
Esteves, T; Macedo, R; Oliveira, R; Paulo, J;

Publicação
2023 53RD ANNUAL IEEE/IFIP INTERNATIONAL CONFERENCE ON DEPENDABLE SYSTEMS AND NETWORKS WORKSHOPS, DSN-W

Abstract
We present DIO, a generic tool for observing inefficient and erroneous I/O interactions between applications and in-kernel storage systems that lead to performance, dependability, and correctness issues. DIO facilitates the analysis and enables near real-time visualization of complex I/O patterns for data-intensive applications generating millions of storage requests. This is achieved by non-intrusively intercepting system calls, enriching collected data with relevant context, and providing timely analysis and visualization for traced events. We demonstrate its usefulness by analyzing two production-level applications. Results show that DIO enables diagnosing resource contention in multi-threaded I/O that leads to high tail latency and erroneous file accesses that cause data loss.

2023

A Method for Detecting Pathologies in Concrete Structures Using Deep Neural Networks

Autores
Diniz, JDN; de Paiva, AC; Braz, G; de Almeida, JDS; Cunha, AC; Cunha, AMTD; Cunha, SCAPD;

Publicação
APPLIED SCIENCES-BASEL

Abstract
Pathologies in concrete structures, such as cracks, splintering, efflorescence, corrosion spots, and exposed steel bars, can be visually evidenced on the concrete surface. This paper proposes a method for automatically detecting these pathologies from images of the concrete structure. The proposed method uses deep neural networks to detect pathologies in these images. This method results in time savings and error reduction. The paper presents results in detecting the pathologies from wide-angle images containing the overall structure and also for the specific pathology identification task for cropped images of the region of the pathology. Identifying pathologies in cropped images, the classification task could be performed with 99.4% accuracy using cross-validation and classifying cracks. Wide images containing no, one, or several pathologies in the same image, the case of pathology detection, could be analyzed with the YOLO network to identify five pathology classes. The results for detection with YOLO were measured with mAP, mean Average Precision, for five classes of concrete pathology, reaching 11.80% for fissure, 19.22% for fragmentation, 5.62% for efflorescence, 27.24% for exposed bar, and 24.44% for corrosion. Pathology identification in concrete photos can be optimized using deep learning.

2023

TweetStream2Story: Narrative Extraction from Tweets in Real Time

Autores
Castro, M; Jorge, A; Campos, R;

Publicação
ADVANCES IN INFORMATION RETRIEVAL, ECIR 2023, PT III

Abstract
The rise of social media has brought a great transformation to the way news are discovered and shared. Unlike traditional news sources, social media allows anyone to cover a story. Therefore, sometimes an event is already discussed by people before a journalist turns it into a news article. Twitter is a particularly appealing social network for discussing events, since its posts are very compact and, therefore, contain colloquial language and abbreviations. However, its large volume of tweets also makes it impossible for a user to keep up with an event. In this work, we present TweetStream2Story, a web app for extracting narratives from tweets posted in real time, about a topic of choice. This framework can be used to provide new information to journalists or be of interest to any user who wishes to stay up-to-date on a certain topic or ongoing event. As a contribution to the research community, we provide a live version of the demo, as well as its source code.

2023

Report on the 1st Workshop on Implicit Author Characterization from Texts for Search and Retrieval (IACT 2023) at SIGIR 2023

Autores
Litvak, M; Rabaev, I; Campos, R; Jorge, AM; Jatowt, A;

Publicação
SIGIR Forum

Abstract

2023

Optical Fiber Surface Plasmon Resonance for Glucose Detection

Autores
Cunha, C; Silva, S; Coelho, LCC; Frazão, O; Novais, S;

Publicação
EPJ Web of Conferences

Abstract
This work proposes a sensor that utilizes a transmission scheme for measuring glucose aqueous solutions based on surface plasmon resonance. A comparison between the performance of two sensors with similar lengths and different diameters is performed. The first sensor comprises a multimode optical fiber with a diameter of 400 µm and a 10 mm middle section of the cladding removed. The second sensor is similar, except that the fiber has a diameter of 600 µm. The sensors were evaluated for their performance in measuring glucose concentrations ranging from 0.0001 to 0.5000 g/mL. The 400 µm sensor demonstrated high sensitivity however, the sensor with a diameter of 600 µm attained a slightly higher maximum sensitivity of 322.0 nm/(g/mL).

2023

A reinforcement learning approach to explore the role of social expectations in altruistic behavior

Autores
Castanon, R; Campos, FA; Villar, J; Sanchez, A;

Publicação
SCIENTIFIC REPORTS

Abstract
While altruism has been studied from a variety of standpoints, none of them has proven sufficient to explain the richness of nuances detected in experimentally observed altruistic behavior. On the other hand, the recent success of behavioral economics in linking expectation formation to key behaviors in complex societies hints to social expectations having a key role in the emergence of altruism. This paper proposes an agent-based model based upon the Bush-Mosteller reinforcement learning algorithm in which agents, subject to stimuli derived from empirical and normative expectations, update their aspirations (and, consequently, their future cooperative behavior) after playing successive rounds of the Dictator Game. The results of the model are compared with experimental results. Such comparison suggests that a stimuli model based on empirical and normative expectations, such as the one presented in this work, has considerable potential for capturing the cognitive-behavioral processes that shape decision-making in contexts where cooperative behavior is relevant.

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