Abstract
Conventional localization systems typically rely on fixed transmission parameters and signal types, limiting their effectiveness in variable and dynamic underwater environments. The present work investigates the potential of adaptable transmission strategies to enhance signal detection estimation for localization purposes. Two widely used signal types, Linear Frequency Modulated (LFM) chirps and BPSK-modulated Msequences, are selected due to their strong autocorrelation properties and robustness to noise. A matched-filter detection approach based on peak correlation is implemented and evaluated. The analysis examines the impact of varying transmission parameters, namely transmission power and signal duration, on detection performance, which inherently influences time-based localization. Results demonstrate that reconfiguring signal parameters significantly reduces estimation dispersion. Moreover, the optimal signal type is shown to depend on the acoustic scenario, with no single waveform consistently outperforming the other. These findings highlight the value of reconfigurable acoustic systems capable of adapting acoustic systems characteristics based on environmental or system feedback, thereby improving localization performance in navigation tasks and dynamic underwater conditions. © 2025 Marine Technology Society.

Abstract
As digital design methodologies and tools are evolving to higher abstraction levels, teaching the low-level concepts of digital electronic system design is becoming increasingly challenging. The raise of the design abstraction level and, more recently, the ability of AI-assisted automated design is pushing the interest of students away from the lower-level details of the digital world. Nevertheless, digital electronic systems are (still) made of transistors, gates and flip-flops, and people do need to keep this basic knowledge to be able to build efficient circuits, understand them and develop the essential electronic design automation tools. For learning these subjects, hands-on experimentation, and learning by doing, is proven to be an effective tool, and when students finally see and feel the results of their designs, motivation raises rapidly. This paper presents the technical aspects of a platform created in the DECEL project to support an FPGA-based remote laboratory based on a commercial single-board computer that can be located somewhere in the Internet. This computer runs a Linux operating system and is based on an AMD/XILINX device that integrates in the same chip an ARM Cortex A9 CPU and a region of FPGA programmable logic. The user develops a digital circuit using standard hardware-description languages (Verilog or VHDL) and runs the implementation tools for the target FPGA using a very simple web interface running in a remote server.

Abstract
This demo shows an infrastructure that allows for easy implementation of real remote labs. In this infrastructure, several nodes are remotely interconnected by publishing/subscribing MQTT messages. There are physical nodes capable of connecting to real circuits and/or sensors/actuators, and virtual nodes that implement simulated versions of circuits that interact remotely with signals from other nodes. The latencies that occur are low enough for groups of students located in different physical locations to benefit from a near real-time experience in interacting with the circuits thus implemented.

Abstract
Squalius alburnoides (Steindachner, 1866) is an endemic threatened species from the Iberian Peninsula. Here, we report the first observations of intraspecific cleaning behavior in isolated summer pools in the Guadiana River Basin (Portugal). We found that focal S. alburnoides solicited cleaning by adopting an immobile tail-stand position known as posing, which immediately signaled a response to a few conspecifics that approached and inspect them. Our study expands the list of cleanerfish species in freshwaters, giving emphasis to the importance of mutual positive behavior within an endangered species, particularly when facing seasonal disturbance.

Abstract
This article addresses the 3-D localization of a stand-alone acoustic beacon based on the Principle of Synthetic Baseline using a single receiver on board a surface vehicle. The process only uses the passive reception of an acoustic signal with no explicit synchronization, interaction, or communication with the acoustic beacon. The localization process exploits the transmission of periodic signals without synchronization to a known time reference to estimate the time-of-arrival (ToA) with respect to an absolute time basis provided by the global navigation satellite system (GNSS). We present the development of the acoustic signal acquisition system, the signal processing algorithms, the data processing of times-of-arrival, and an estimator that uses times-of-arrival and the coordinates where they have been collected to obtain the 3-D position of the acoustic beacon. The proposed approach was validated in a real field application on a search for an underwater glider lost in September 2021 near the Portuguese coast.