http://hdl.handle.net/10366/160355 2026-04-17T21:47:47Z http://hdl.handle.net/10366/160469 [EN]This paper reports on optimization of the parameters, by mean of electromagnetic simulations to obtain the values of the parameters that permit optimal conditions for terahertz (THz) radiation detection using the terajet effect generated by inserting a cuboid-shaped mesoscopic dielectric particle in the optical path at in the front of the rectifier. The obtained results show that the length of edge of the cuboid is the key parameter that conditions the performance of the detection system. A substantial gain is obtained under optimal conditions. 2022-08-30T00:00:00Z http://hdl.handle.net/10366/160468 [EN]We report on a study of the coupling of electromagnetic radiation to a strained-silicon MODFETs used as sub-THz terahertz detector. In particular, the effect of the polarization of the incoming beam as well as the role of the bonding wires on the photoresponse generated were addressed. Two tones were considered: 0.15 and 0.30THz. Results show that the device is sensitive to the beam polarization, especially when the beam polarization is perpendicular to the transistor channel under excitation at 0.15THz. We also demonstrated that the bonding wires play a preponderant role in the coupling of the incoming radiation to the channel of the FET under excitation at 0.15THz while they have a minor role at higher frequencies (0.3THz). 2021-08-29T00:00:00Z http://hdl.handle.net/10366/160464 Indoor navigation, an innovative service built on indoor localisation, is a game-changer for travellers. This paper introduces a unique multimodal, dynamic indoor navigation service for indoor spaces. The novelty of this service lies in its seamless integration with outdoor routers, paving the way for a comprehensive door-to-door trip planner. The service's indoor multimodality is a key focus, considering accessibility options profiling and incorporating limited vehicular paths (e.g., internal buses in airports). The service's indoor dynamism is another standout feature involving real-time monitoring of events within the navigation path. The integration with outdoor routers is a significant achievement, primarily through the establishment of common interconnection points (shared points where indoor and outdoor navigation systems can exchange data) and a common data format structure (a standardised way of representing and exchanging navigation data). The proposed navigation service was put to the test in three real deployments at Berlin Tegel (TXL), Berlin Schönefeld (SXF), and Palma International (PMI) airports. Users travelling between these cities experienced the system's rapid detection of mechanical problems (e.g., travellators or elevators out of order) and incidents (e.g., temporarily non-navigable areas). The service's integration with other travel assistants and services, such as evaluating waiting times at check-in counters and security checkpoints, provided more accurate estimations of indoor navigation travel time and helped avoid agglomeration. These successful real-world validations underscore the service's effectiveness and reliability. The findings indicate that this innovative service significantly improves the travel experience by enhancing the planning and scheduling of movements from origin to destination. The validation showed an increase in travel efficiency, reduced wait times, and better accessibility options for travellers, underscoring the practical benefits of the proposed door-to-door navigation system. 2024-07-23T00:00:00Z http://hdl.handle.net/10366/160463 Nowadays, in contemporary building and energy management systems (BEMSs), the predominant approach involves rule-based methodologies, typically employing supervised or unsupervised learning, to deliver energy-saving recommendations to building occupants. However, these BEMSs often suffer from a critical limitation—they are primarily trained on building energy data alone, disregarding crucial elements such as occupant comfort and preferences. This inherent lack of adaptability to occupants significantly hampers the effectiveness of energy-saving solutions. Moreover, the prevalent cloud-based nature of these systems introduces elevated cybersecurity risks and substantial data transmission overheads. In response to these challenges, this article introduces a cutting-edge edge computing architecture grounded in virtual organizations, federated learning, and deep reinforcement learning algorithms, tailored to optimize energy consumption within buildings/homes and facilitate demand response. By integrating energy efficiency measures within virtual organizations, which dynamically learn from real-time inhabitant data while prioritizing comfort, our approach effectively optimizes inhabitant consumption patterns, ushering in a new era of energy efficiency in the built environment. 2023-01-01T00:00:00Z http://hdl.handle.net/10366/160382 We report on the enhancement of responsivity by more than one order of magnitude of a silicon-based sub-terahertz detector when a mesoscopic dielectric particle was used to localize incident radiation to a sub-wavelength volume and focus it directly onto the detector. A strained-silicon modulation field-effect transistor was used as a direct detector on an incident terahertz beam at 0.3 THz. A systematic study in which Teflon cubes were placed in front of the detector to focus the terahertz beam was performed. In this study, cubes with different sizes were investigated, and an enhancement of the responsivity up to 11 dB was observed for a cube with an edge length of 3.45 mm (or 3.45λ). Electromagnetic simulation results were in good agreement with the experimental ones and demonstrated that the size of the mesoscopic particle plays an important role in focalizing the electric field within an area below the diffraction limit. This approach provides an efficient, uncostly, and easy to implement method to substantially improve the responsivity and noise equivalent power of sub-terahertz detectors. 2021-06-21T00:00:00Z http://hdl.handle.net/10366/160381 An infrared (IR) pyroelectric detector was investigated for terahertz (THz) detection using the principle of the terajet effect, which focuses the beam beyond the diffraction limit. The terahertz beam was coupled to the detector’s optical window through a two-wavelength-dimension dielectric cubic particle-lens based on the terajet effect. We experimentally demonstrate an enhancement of about 6 dB in the sensitivity under excitation of 0.2 THz without degradation of the noise equivalent power value. The results show that the proposed method could be applied to increase the sensitivity of various commercial IR sensors for THz applications that do not require modification of the internal structure, and it may apply also to acoustics and plasmonic detectors. 2021-07-29T00:00:00Z http://hdl.handle.net/10366/160380 This paper reports on a study of the response of a T-gate strained-Si MODFETs (modulationdoped field-effect transistor) under continuous-wave sub-THz excitation. The sub-THz response was measured using a two-tones solid-state source at 0.15 and 0.30 THz. The device response in the photovoltaic mode was non-resonant, in agreement with the Dyakonov and Shur model for plasma waves detectors. The maximum of the photoresponse was clearly higher under THz illumination at 0.15 THz than at 0.3 THz. A numerical study was conducted using three-dimensional (3D) electromagnetic simulations to delve into the coupling of THz radiation to the channel of the transistor. 3D simulations solving the Maxwell equations using a time-domain solver were performed. Simulations considering the full transistor structure, but without taking into account the bonding wires used to contact the transistor pads in experiments, showed an irrelevant role of the gate length in the coupling of the radiation to the device channel. Simulations, in contradiction with measurements, pointed to a better response at 0.3 THz than under 0.15 THz excitation in terms of the normalized electric field inside the channel. When including four 0.25 mm long bonding wires connected to the contact pads on the transistor, the normalized internal electric field induced along the transistor channel by the 0.15 THz beam was increased in 25 dB, revealing, therefore, the important role played by the bonding wires at this frequency. As a result, the more intense response of the transistor at 0.15 THz than at 0.3 THz experimentally found, must be attributed to the bonding wires. 2021-01-20T00:00:00Z