Percorrer por autor "Matos, Tiago"
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- A Demonstrator for future fiber-optic active SMART repeatersPublication . Cruz, Nuno A.; Silva, António; Zabel, Friedrich; Ferreira, Bruno; Jesus, Sergio; Martins, Marcos S.; Pereira, Eduardo; Matos, Tiago; Viegas, Ruben; Rocha, João; Faria, JoãoThe deep-sea environment still presents many challenges for systematic, comprehensive data acquisition. The current generation of SMART cables incorporates low-power sensors in long-range telecommunication cables to improve knowledge of ocean variables, aid in earthquake and tsunami warnings, and enhance coastal protection. The K2D Project seeks to expand SMART cables' capabilities by increasing the diversity of sensors along deep water cables, integrating active devices, and leveraging mobile platforms like deep-water AUVs, thereby improving spatial coverage and advancing ocean monitoring technology. This paper discusses a demonstration of these capabilities, focusing on the description of the main building blocks developed along the project, with results from a sea deployment in September 2023.
- Erratum: Martins, M.S., et al. Wideband and wIde beam polyvinylidene difluoride (PVDF) acoustic transducer for broadband underwater. Sensors 2019, 19, 3991Publication . Martins, Marcos; Faria, Carlos L.; Matos, Tiago; Gonçalves, L. M.; Cabral, José; Silva, António; Jesus, SergioThe authors wish to make the following erratum to this paper [...].
- Network nodes for ocean data exchange through submarine fiber optic cable repeatersPublication . Martins, M. S.; Cruz, Nuno A.; Silva, António; Ferreira, Bruno; Zabel, Fred; Matos, Tiago; Jesus, Sergio; Pinto, André; Pereira, Eduardo; Matos, Aníbal; Faria, Carlos; Tieppo, Marcos; Goncalves, L. M.; Rocha, João; Faria, JoãoAs humanity progresses and globalization advances, humanized environment and associated systems increase in complexity and size. In earth systems, oceans represent an essential element of equalization and normal functioning. Ocean-atmospheric interactions are nowadays believed to be at the heart of all earth vital signs and climatic behaviours, and therefore are essential to accurate monitoring and understanding of earth systems. The work presented is a preliminary result of the K2D- Knowledge and Data from the Deep to Space, project which addresses the challenge of creating underwater network nodes to provide power and communication to land through the submarine fiber optic cable repeaters. The N2ODE system will consist of a set of subsystems that will allow continuous monitoring and interaction with fixed and mobile underwater devices.
- Remote secure online voting system developmentPublication . Matos, Tiago; Guerreiro, JoelRemote online elections have been studied and applied throughout the years in several countries with different approaches and distinct secure mechanisms. Online elections collect sensitive information therefore, the system, must guarantee confidentiality, integrity, privacy, security and be auditable to ensure a successful and creditable election process. A distinct web-based system approach, as far known, was developed using data processing, backend, storage and frontend components secured by cipher suites and an independent developed asymmetric cryptography key management system. Both, cipher suites and the key manage system, ensure authentication, authorization and vote encryption before storage, making it impossible to visualize election results primary to vote counting initiation and user’s votes choices. The developed system implements a mechanism to verify enabled users accesses in a specific election and ensure if they already voted, avoiding repeated votes. Encrypts, stores votes and users in distinct database tables to avoid, even with direct database access, the knowledge of who has voted so far and what was the vote direction, displaying statistics information of the already casted number of votes, being, the election committee, able to monitor effectiveness, before the voting period ends. The developed and implemented databases follows ACID (Atomicity, Consistency, Isolation and Durability) properties, assuring each statement in a transaction is treated as a single unit preventing data loss and corruption, ensuring consistency, isolating user transactions, guaranteeing no transaction interferes with another and, on the event of a system failure, is assured that all executed transactions are saved and no data is lost.
- Wideband and wide beam polyvinylidene difluoride (PVDF) acoustic transducer for broadband underwater communicationsPublication . Martins, Marcos; Faria, Carlos; Matos, Tiago; Gonçalves, Luís; Cabral, José; Silva, António; Jesus, SergioThe advances in wireless communications are still very limited when intended to be used on Underwater Communication Systems mainly due to the adverse proprieties of the submarine channel to the acoustic and radio frequency (RF) waves propagation. This work describes the development and characterization of a polyvinylidene difluoride ultrasound transducer to be used as an emitter in underwater wireless communications. The transducer has a beam up to 10° × 70° degrees and a usable frequency band up to 1 MHz. The transducer was designed using Finite Elements Methods and compared with real measurements. Pool trials show a transmitting voltage response (TVR) of approximately 150 dB re µPa/V@1 m from 750 kHz to 1 MHz. Sea trials were carried in Ria Formosa, Faro (Portugal) over a 15 m source-receiver communication link. All the signals were successfully detected by cross-correlation using 10 chirp signals between 10 to 900 kHz.