Cookies
O website necessita de alguns cookies e outros recursos semelhantes para funcionar. Caso o permita, o INESC TEC irá utilizar cookies para recolher dados sobre as suas visitas, contribuindo, assim, para estatísticas agregadas que permitem melhorar o nosso serviço. Ver mais
Aceitar Rejeitar
  • Menu
Publicações

2024

Final Design and Status of the Mid-IR ELT Imager and Spectrograph, METIS

Autores
Brandl, BR; Bettonvil, F; van Boekel, R; Glauser, AM; Quanz, S; Absil, O; Feldt, M; Garcia, P; Glasse, A; Guedel, M; Labadie, L; Meyer, M; Pantin, É; Wang, SY; Van Winckel, H;

Publicação
GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY X

Abstract
The Mid-Infrared ELT Imager and Spectrograph (METIS) will be one of only three 1st-generation science instruments on the 39m Extremely Large Telescope (ELT). METIS will provide diffraction-limited imaging and medium resolution slit-spectroscopy from 3-13 microns (L, M, and N bands), as well as high resolution (R approximate to 100,000) integral field spectroscopy from 2.9-5.3 microns. Both imaging and IFU spectroscopy can be combined with coronagraphic techniques. After the final design reviews of the optics (2021) and the entire system (2022), most hardware procurements have started. In this paper we present an overview of the status of the various ongoing activities. Many hardware components are already in hand, and the manufacturing is in full swing in order to start the assembly and testing of the subsystems in 2024 toward first light at the telescope in 2028/29. This rather brief paper only provides an overview of the project status. For more information, we refer to the detailed instrument paper which will be published soon.

2024

Extending C2 Traffic Detection Methodologies: From TLS 1.2 to TLS 1.3-enabled Malware

Autores
Barradas, D; Novo, C; Portela, B; Romeiro, S; Santos, N;

Publicação
PROCEEDINGS OF 27TH INTERNATIONAL SYMPOSIUM ON RESEARCH IN ATTACKS, INTRUSIONS AND DEFENSES, RAID 2024

Abstract
As the Internet evolves from TLS 1.2 to TLS 1.3, it offers enhanced security against network eavesdropping for online communications. However, this advancement also enables malicious command and control (C2) traffic to more effectively evade malware detectors and intrusion detection systems. Among other capabilities, TLS 1.3 introduces encryption for most handshake messages and conceals the actual TLS record content type, complicating the task for state-of-the-art C2 traffic classifiers that were initially developed for TLS 1.2 traffic. Given the pressing need to accurately detect malicious C2 communications, this paper examines to what extent existing C2 classifiers for TLS 1.2 are less effective when applied to TLS 1.3 traffic, posing a central research question: is it possible to adapt TLS 1.2 detection methodologies for C2 traffic to work with TLS 1.3 flows? We answer this question affirmatively by introducing new methods for inferring certificate size and filtering handshake/protocolrelated records in TLS 1.3 flows. These techniques enable the extraction of key features for enhancing traffic detection and can be utilized to pre-process data flows before applying C2 classifiers. We demonstrate that this approach facilitates the use of existing TLS 1.2 C2 classifiers with high efficacy, allowing for the passive classification of encrypted network traffic. In our tests, we inferred certificate sizes with an average error of 1.0%, and achieved detection rates of 100% when classifying traffic based on certificate size, and over 93% when classifying TLS 1.3 traffic behavior after training solely on TLS 1.2 traffic. To our knowledge, these are the first findings to showcase specialized TLS 1.3 C2 traffic classification.

2024

Manipulation of Microparticles in Optofluidic Devices Fabricated by Femtosecond Laser Micromachining

Autores
Cameira, C; Maia, M; Marques, PVS;

Publicação
EPJ Web of Conferences

Abstract
This study reports the fabrication of three-dimensional microfluidic channels in fused silica, using femtosecond laser micromachining, to achieve two-dimensional hydrodynamic flow focusing in either the horizontal or the vertical directions. Spatial focusing of 3 µm polystyrene particles was successfully demonstrated, showing the ability of the fabricated devices to confine microparticles within a 6 µm layer over a channel width of 420 µm and within a 5 µm layer over a channel height of 260 µm. Integration of laser-direct written optical waveguides inside a microfluidic chip and orthogonal to the channel also enabled the implementation of a dual-beam optical trap, with trapping of polystyrene microparticles using a 1550 nm beam being demonstrated. © The Authors.

2024

Enhancing robustness to forecast errors in availability control for airline revenue management

Autores
Gonçalves, T; Almada Lobo, B;

Publicação
Journal of Revenue and Pricing Management

Abstract
Traditional revenue management systems are built under the assumption of independent demand per fare. The fare adjustment theory is a methodology to adjust fares that allows for the continued use of optimization algorithms and seat inventory control methods, even with the shift toward dependent demand. Since accurate demand forecasts are a key input to this methodology, it is reasonable to assume that for a scenario with uncertainties it may deliver suboptimal performance. Particularly, during and after COVID-19, airlines faced striking challenges in demand forecasting. This study demonstrates, firstly, the theoretical dominance of the fare adjustment theory under perfect conditions. Secondly, it lacks robustness to forecast errors. A Monte Carlo simulation replicating a revenue management system under mild assumptions indicates that a forecast error of ±20% can potentially prompt a necessity to adjust the margin employed in the fare adjustment theory by -10%. Moreover, a tree-based machine learning model highlights the forecast error as the predominant factor, with bias playing an even more pivotal role than variance. An out-of-sample study indicates that the predictive model steadily outperforms the fare adjustment theory. © The Author(s), under exclusive licence to Springer Nature Limited 2024.

2024

Analysis of Constructive Heuristics with Cuckoo Search Algorithm, Firefly Algorithm and Simulated Annealing in Scheduling Problems

Autores
Moreira, C; Costa, C; Santos, AS; Madureira, AM; Barbosa, M;

Publicação
FLEXIBLE AUTOMATION AND INTELLIGENT MANUFACTURING: ESTABLISHING BRIDGES FOR MORE SUSTAINABLE MANUFACTURING SYSTEMS, FAIM 2023, VOL 2

Abstract
Nowadays, decision making is one of the most important and influential aspects of everyday life, and the application of metaheuristics and heuristics facilitates the process. Thus, this paper presents a performance analysis of the combination of constructive heuristics used to generate initial solutions for metaheuristics applied to scheduling problems. Namely, Nawaz, Enscore, and Ham Heuristic (NEH), Palmer Heuristic and Campbell, Dudek, and Smith Heuristic (CDS) with Cuckoo Search, Firefly Algorithm and Simulated Annealing. The aim is to compare the performance of these combinations to analyse the efficiency, effectiveness and robustness of each. All combinations were analysed in an in-depth computational study and then subjected to a statistical study to support an accurate analysis of the results. The results of the analysis show that the Firefly Algorithm associated with NEH, despite having a high runtime, performs better than the other combinations. However, the best effectiveness-efficiency ratio corresponds to SA-Palmer and SA-CDS.

2024

INDICADORES PARA ANÁLISE DA INDÚTRIA CRIATIVA EM PORTUGAL: estruturação do observatório na Universidade do Porto

Autores
Manuel Figueiredo Lima, C; Costa Martins, T; Manuela Gomes de Azevedo Pinto, M;

Publicação
Comunicação & Inovação

Abstract
O artigo explora a criação de um sistema de indicadores para um observatório da Indústria Criativa (IC) na Universidade do Porto. A pesquisa, de natureza exploratória, descreve e propõe um framework conceitual para a análise de indicadores na IC. Destaca a importância da interdisciplinaridade, integrando perspectivas econômicas e infocomunicacionais. Aborda a complexidade na definição e classificação das atividades econômicas desse setor. O artigo também apresenta uma proposta em desenvolvimento para o observatório e sugere o uso de modelos descritivos, preditivos e prescritivos em etapas futuras.

  • 562
  • 4574