Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

2023

The 1st International Workshop on Implicit Author Characterization from Texts for Search and Retrieval (IACT'23)

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

Publication
PROCEEDINGS OF THE 46TH INTERNATIONAL ACM SIGIR CONFERENCE ON RESEARCH AND DEVELOPMENT IN INFORMATION RETRIEVAL, SIGIR 2023

Abstract
The first edition of the Implicit Author Characterization from Texts for Search and Retrieval (IACT'23) aims at bringing to the forefront the challenges involved in identifying and extracting from texts implicit information about authors (e.g., human or AI) and using it in IR tasks. The IACT workshop provides a common forum to consolidate multi-disciplinary efforts and foster discussions to identify the wide-ranging issues related to the task of extracting implicit author-related information from the textual content, including novel tasks and datasets. We will also discuss the ethical implications of implicit information extraction. In addition, we announce a shared task focused on automatically determining the literary epochs of written books.

2023

DSO framework to handle high participation of DER in electricity markets

Authors
Fonseca, NS; Soares, F; Coelho, A; Iria, J;

Publication
2023 19TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET, EEM

Abstract
This paper proposes a new decentralized framework for distribution system operators (DSO) to evaluate the network feasibility of the aggregators' bids and remunerate them in case of providing network support services. Compared to other state-of-the-art approaches, this framework is characterized as being more efficient in terms of communication and computational requirements, which is a great advantage for real world applications. The new framework includes a novel optimization model to decide if aggregators' bids should be curtailed or not to ensure network security and minimize DSO costs. To evaluate and compare the proposed DSO framework against the current one, we used the IEEE 69-bus network with three aggregators of distributed energy resources (DER) from the Iberian electricity market. Our experiments show that the proposed DSO framework ensures distribution network security, while the current framework in place in the Iberian Peninsula does not. In addition, we also studied three curtailment policies for the new DSO framework. The results show that minimizing curtailment costs is the most cost-effective policy for the DSO, compared to the other two policies focused on minimizing linear and squared curtailments.

2023

Execution Time Program Verification with Tight Bounds

Authors
Silva, AC; Barbosa, M; Florido, M;

Publication
PRACTICAL ASPECTS OF DECLARATIVE LANGUAGES, PADL 2023

Abstract
This paper presents a proof system for reasoning about execution time bounds for a core imperative programming language. Proof systems are defined for three different scenarios: approximations of the worst-case execution time, exact time reasoning, and less pessimistic execution time estimation using amortized analysis. We define a Hoare logic for the three cases and prove its soundness with respect to an annotated cost-aware operational semantics. Finally, we define a verification conditions (VC) generator that generates the goals needed to prove program correctness, cost, and termination. Those goals are then sent to the Easycrypt toolset for validation. The practicality of the proof system is demonstrated with an implementation in OCaml of the different modules needed to apply it to example programs. Our case studies are motivated by real-time and cryptographic software.

2023

Joint Traffic and Obstacle-aware UAV Positioning Algorithm for Aerial Networks

Authors
Shafafi, K; Coelho, A; Campos, R; Ricardo, M;

Publication
2023 IEEE 9TH WORLD FORUM ON INTERNET OF THINGS, WF-IOT

Abstract
Unmanned Aerial Vehicles (UAVs) are increasingly used as cost-effective and flexible Wi-Fi Access Points (APs) and cellular Base Stations (BSs) to enhance Quality of Service (QoS). In disaster management scenarios, UAV-based networks provide on-demand wireless connectivity when traditional infrastructures fail. In obstacle-rich environments like urban areas, reliable high-capacity communications links depend on Line-of-Sight (LoS) availability, especially at higher frequencies. Positioning UAVs to consider obstacles and enable LoS communications represents a promising solution that requires further exploration and development. The main contribution of this paper is the Traffic- and Obstacle-aware UAV Positioning Algorithm (TOPA). TOPA takes into account the users' traffic demand and the need for LoS between the UAV and the ground users in the presence of obstacles. The network performance achieved when using TOPA was evaluated through ns-3 simulations. The results show up to 100% improvement in the aggregate throughput without compromising fairness.

2023

The 6G Ecosystem as Support for IoE and Private Networks: Vision, Requirements, and Challenges

Authors
Serôdio, C; Cunha, J; Candela, G; Rodriguez, S; Sousa, XR; Branco, F;

Publication
FUTURE INTERNET

Abstract
The emergence of the sixth generation of cellular systems (6G) signals a transformative era and ecosystem for mobile communications, driven by demands from technologies like the internet of everything (IoE), V2X communications, and factory automation. To support this connectivity, mission-critical applications are emerging with challenging network requirements. The primary goals of 6G include providing sophisticated and high-quality services, extremely reliable and further-enhanced mobile broadband (feMBB), low-latency communication (ERLLC), long-distance and high-mobility communications (LDHMC), ultra-massive machine-type communications (umMTC), extremely low-power communications (ELPC), holographic communications, and quality of experience (QoE), grounded in incorporating massive broad-bandwidth machine-type (mBBMT), mobile broad-bandwidth and low-latency (MBBLL), and massive low-latency machine-type (mLLMT) communications. In attaining its objectives, 6G faces challenges that demand inventive solutions, incorporating AI, softwarization, cloudification, virtualization, and slicing features. Technologies like network function virtualization (NFV), network slicing, and software-defined networking (SDN) play pivotal roles in this integration, which facilitates efficient resource utilization, responsive service provisioning, expanded coverage, enhanced network reliability, increased capacity, densification, heightened availability, safety, security, and reduced energy consumption. It presents innovative network infrastructure concepts, such as resource-as-a-service (RaaS) and infrastructure-as-a-service (IaaS), featuring management and service orchestration mechanisms. This includes nomadic networks, AI-aware networking strategies, and dynamic management of diverse network resources. This paper provides an in-depth survey of the wireless evolution leading to 6G networks, addressing future issues and challenges associated with 6G technology to support V2X environments considering presenting +challenges in architecture, spectrum, air interface, reliability, availability, density, flexibility, mobility, and security.

2023

A Novel Approach to the Two-Dimensional Cargo Load Problem

Authors
Mateus, F; Santos, AS; Brito, MF; Madureira, AM;

Publication
Lecture Notes in Networks and Systems

Abstract
The transport and logistics sector, which include freight forwarders companies, constitutes a vast network of entities that are central to a good performance in services. With the COVID-19 pandemic and its effects on the global economy, there was a huge shortage in the number of containers available, thus creating the need to optimize the loading of available equipment to avoid waste and maximize profits from each export. The present work presents a novel approach where a set of restrictions were created that, applied in synergy with the Non-Linear GRG algorithm, aim to allocate the boxes in different consecutive lines until forming a wall, and, therefore, the walls complete the container, in order to maximize the occupancy on it. To validate the proposed approach a prototype was developed and studied in real-world problem where the solutions resulted in occupations around 80% to 90%. Thus, we can foresee the importance of the proposed approach in decision-making regarding container consolidation services. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

  • 529
  • 4365