arXiv subjects

Antonio Lazaro

Publications and source records attributed to Antonio Lazaro.

7 recordsLinked to original sources

arXiv2026

To Tab or Not to Tab: Measuring Critical Engagement in AI Code Completion Tools Using Behavioral Signals and Attention Checks

AI code completion tools, such as Github Copilot, provide students with code suggestions to help them write programs. However, recent qualitative studies suggest that students fail to critically evaluate these suggestions. We present Clover, a code completion tool that logs students' interactions with code suggestions and additionally offers attention checks to probe reflective engagement during programming tasks. We also develop a taxonomy of behavioral interaction metrics for AI-assisted programming, informed by literature. We analyzed relationships between interaction patterns, engagement with attention checks, and task performance. We observed that higher rates of tab accept were associated with lower attention check performance, while increased dwell time was associated with higher attention check performance. We conclude by discussing how programming process data and attention checks might support reflective engagement in AI-assisted programming.

cs.HC↗

arXiv2024

Reduced-Order Model of Power Converters to Optimize Power Hardware-In-the-Loop Technology in Dc-Distributed Systems

The Power Hardware-In-the-Loop (PHIL) technology provides a powerful tool for testing scenarios where there is a high-power interchange, in which the performance of field tests can be very complex or expensive. When performing PHIL simulations of systems with a high number of components, such as DC-distributed systems on a ship or aircraft, the use of switched or average models of the converters can require the use of expensive commercial real-time digital simulators (RTDS) reducing the advantages of these technology. This paper is focused on the proposal of a reduced order model of converters to be able to perform PHIL analysis of Dc-distributed systems using low resources of the required real-time digital simulator. The paper validates that the proposed reduced-order model is able to determine the stability on the Dc-distributed system in comparison with more complex converter models. Moreover, a comparison between both models regarding the required resources in the implementation in a commercial RTDS platform is performed to validate the benefits of the proposed model in performing PHIL analysis of large power distribution systems.

eess.SY↗

arXiv2024

Study of Applicability of Simple Closed Loop Input Impedance Model for Grid-Tie Inverters

In recent years the need for DC distribution buses has increased considerably. As it can be noticed in the transport for example the distribution systems of the more electric aircrafts, ships, or electric cars. Given the complexities of the systems presented above, the need to use more and more switched power converters has arisen. The main problem of the connection of multiple controlled switched converters acting as source and load is the degradation of stability that occurs on the DC distribution bus due to the converter interactions. To study the stability in the distribution bus there are some wellestablished criteria. These criteria require knowledge of the input impedance of the converters that act as load and the output impedance of the equipment that acts as source. In order to reduce the complexity of obtaining the input impedance a model based on a controlled converter acting as a constant power load (CPL) is commonly used. This article studies the accuracy of this model for a commonly used topology in distribution systems nowadays, Two Level Voltage Source Converter (2L-VSC), studying different scenarios that make the model become inaccurate.

eess.SY↗

arXiv2024

Analysis and implementation of the Buck-Boost Modified Series Forward converter applied to photovoltaic systems

The mismatching phenomenon is one of the main issues in photovoltaic (PV) applications. It could reduce the generated power of a string when a PV panel has different performances from the other PV panels connected to the same string. Distributed Maximum Power Point Tracking (DMPPT) architectures are one of the most promising solutions to overcome the drawbacks associated with mismatching phenomena in PV applications. In this kind of architectures, a DC-DC module integrated converter (MIC) manages each PV panel, isolating it from the rest of the PV panels, for harvesting the maximum available power from the Sun. Due to the high number of DCDC converters used in a grid-tied PV installation, the most desired MIC requirements are high efficiency, low cost and the capability of voltage step-up and step-down. This paper proposes the Buck-Boost Modified Forward (BBMSF) converter as a good candidate to be applied in DMPPT architectures. A complete analysis of the BBMSF converter is carried out, including the steady-state analysis as well as the small signal analysis in continuous conduction mode. The main advantages of the BBMSF converter are its step-up and step-down voltage transfer function; a higher simplicity, since it only includes a single controlled switch; the soft switching characteristics in all the diodes and MOSFET, reaching in some cases ZVS and ZCS, and yielding high efficiencies; the use of an autotransformer, with better performances than a typical Forward transformer; and the good dynamic performance, like the Forward converter ones. The theoretical analyses are validated through the experimental results in a 225 W BBMSF prototype designed and built under the requirements of a 100 kW grid-tied PV installation, achieving an efficiency up to 93.6%.

eess.SY↗

arXiv2024

Analysis, design, and implementation of the AFZ converter applied to photovoltaic systems

Grid-tied photovoltaic (PV) installations with Distributed Maximum Power Point Tracking (DMPPT) architectures include a DC-DC Module Integrated Converter (MIC) for managing each PV panel, isolating it from the others, reducing the mismatching effect and maximizing the harvested power. In this paper, the Autotransformer Forward converter with type-Zeta resonant reset (AFZ) is proposed as a DMPPT architecture MIC candidate. The main characteristics of the AFZ converter are the high versatility due to its voltage step-up and step-down capability; the use of an optimized autotransformer with only two windings, reducing the complexity and power losses of this component; the good dynamic performances, like the Forward converter ones; the low number of components and the simplicity and high feasibility associated to the use of just one active switch. Besides, soft switching transitions are achieved thanks to the autotransformer type-Zeta resonant reset. The steady-state theoretical analysis, considering the effect of the autotransformer leakage inductance, is presented. The converter is also studied in the frequency domain, obtaining the small-signal transfer functions. A design procedure based on the requirements of a 100 kW grid-tied photovoltaic installation is described, yielding in a 225 W prototype with efficiencies up to 95.6 %. Experimental results validate the theoretical analysis.

eess.SY↗

arXiv2024

Extension of the Injected-Absorbed-Current Method applied to DC-DC Converters with Input Filter, Output Post-filter and Feedforward Compensations

In railway applications, it is common to use an LC filter connected between the catenary and the input port of the main converter of the auxiliary and traction systems. In addition, in the auxiliary systems, there is a converter operating as a battery charger, which requires a very low ripple in the output current and output voltage, so a postfilter may be placed at the output port of the converter. This article proposes a step-by-step methodology to extend the injected-absorbed-current (IAC) method in order to obtain transfer functions that consider the effects of the input filter, output postfilter, and some feedforward compensations. The proposed methodology allows reusing the characteristic coefficients of the DC-DC converter model derived from the existing IAC method. One of the advantages of the proposed methodology is that the transfer functions obtained in this article are valid for cases where both, one or none of the filters, are implemented. Finally, for the experimental validation of the proposed methodology, the phase-shifted full-bridge converter was selected as a convenient example. Furthermore, the experimental measurements have been performed on two prototypes.

eess.SY↗

arXiv2018

Chipless Dielectric Constant Sensor for Structural Health Testing

A low-cost chipless RFID sensor tag to determine the dielectric properties of materials is presented. The sensor is based on a depolarizing dipole resonator loaded with printed capacitors whose capacitance depends on the permittivity of the material located on contact with the tag. The permittivity is obtained from the shift of the resonance frequency. The resonator is tested both individually as well as placed on a periodic arrangement so as to form a frequency selective structure (FSS) to increase the cross- polar radar cross section, thus facilitating the tag detection. The proposed structure and measurement procedure is particularly suitable for the characterization of civil materials as a nondestructive testing (NDT).

physics.app-ph↗