Bicycles are rapidly gaining popularity as a sustainable mode of transportation around the world. Furthermore, the smart bicycle paradigm enables increased use through the Internet of Things applications (e.g., GPS tracking systems). This new paradigm introduces energy autonomy as a new challenge. The energy harvesting technology can capture the energy present in the cycling environment (e.g., kinetic or solar) to give this autonomy. The kinetic energy source is more stable and dense in this environment. There are several wheel kinetic harvesters on the market, ranging from low-complexity dynamos used to power bicycle lights to smart harvester systems that harvest kinetic energy while braking and cycling and store it for when it is needed to power sensors and other electronics loads. Perhaps the hub and the “bottle” dynamos are the most commercially successful systems because of their cost-effective design. Furthermore, the bottle generator is very inexpensive, yet it suffers from significant energy losses and is unreliable in wet weather due to mechanical friction and wheel slippage in the wheel/generator contact. This paper proposes a cost-effective bicycle harvester based on a novel kinetic-electromagnetic transducer. The proposed harvester allows for the generation and storage of harnessed kinetic energy to power low-power electronics loads when the user requires it (e.g., cell phone charging, lighting). The proposed harvester is made up of a power processing unit, a battery, and an optimized transducer based on a Halbach magnet array. An extensive full-wave electromagnetic simulation was used to evaluate the proposed transducer. Circuit simulation was also used to validate the proposed power unit. The proposed harvester generates a simulated output power of 1.17 W with a power processing unit efficiency of 45.6% under a constant bicycle velocity of 30 km/h.

This paper studies and analyzes the approximation of one-dimensional smooth closed-form functions with compact support using a mixed Fourier series (i.e., a combination of partial Fourier series and other forms of partial series). To explore the potential of this approach, we discuss and revise its application in signal processing, especially because it allows us to control the decreasing rate of Fourier coefficients and avoids the Gibbs phenomenon. Therefore, this method improves the signal processing performance in a wide range of scenarios, such as function approximation, interpolation, increased convergence with quasi-spectral accuracy using the time domain or the frequency domain, numerical integration, and solutions of inverse problems such as ordinary differential equations. Moreover, the paper provides comprehensive examples of one-dimensional problems to showcase the advantages of this approach.

Wireless communication supports various real-world applications, such as aeronautical navigation, satellite and TV broadcasting, wireless LANs, and mobile communications. The inherent characteristics of the electromagnetic spectrum impose constraints on telecommunication channels and their frequency bandwidths within mobile networks. A persistent challenge in these applications is providing high-demand services to mobile users, where frequency assignment problems, also known as channel assignment problems, assume significance. Researchers have developed several modeling approaches to address different facets of this problem, including the management of interfering radio signals, the assessment of available frequencies, and optimization criteria. In this paper, we present improved algorithms for solving the Minimum Span Frequency Assignment Problem in mobile communication systems using the greedy optimization approach known as F/DR. We solved and evaluated twenty well-known benchmark cases to assess the efficacy of our algorithms. Our findings consistently demonstrate that the modified algorithms outperform the F/DR approach with comparable computational complexity. The proposed algorithm notably achieves the following benchmarks: The modified algorithms consistently produce at least one local optimum better than the traditional algorithm in all benchmark tests. In 95% of the benchmarks evaluated, the probability of discovering a local optimum value (calculated by the modified algorithm) that is better than or equal to the one found by the conventional algorithm exceeds 50%.

Hybrid power converters that cascade switched-capacitor stages with conventional LC-based DC/DC switching converters have recently emerged as promising solutions for applications requiring a bipolar DC bus, such as photovoltaic systems and in-chip OLED drivers. However, despite clear advantages in efficiency, compactness, and implementation simplicity, their adoption has been limited due to the lack of accurate modeling and experimental validation. Traditional modeling techniques often fail to capture the static and dynamic behavior of these hybrid topologies. Some previous works either neglected capacitive losses or relied on empirical equivalent models without a clearly defined methodology. The Perilla SIBO (Single-Input Bipolar-Output) Boost Converter is a representative example of this new class of hybrid converters, integrating a conventional Single-Inductor Single-Output (SISO) boost stage with a switched-capacitor inverter. In earlier work, a static model for the Perilla Boost converter was derived using the small-ripple approximation and charge balance principles, assuming matched output capacitors and balanced load conditions—but without considering efficiency estimation. This paper extends the previous model to account for unbalanced loading and mismatched output capacitances and introduces a novel analytical expression to estimate converter efficiency. A comprehensive static modeling and experimental evaluation is presented under realistic operating conditions. The model is validated using a prototype operating across an input voltage range of 3 V to 10 V and delivering output power between 1 W and 20 W. The proposed model achieves a mean absolute percentage error of 5.76% and a standard deviation of 5.68%, offering a reliable tool for steady-state performance prediction. The dynamic modeling of the converter, as well as the development of a systematic design methodology, are beyond the scope of this work.

Objective: The objective of this work was to develop a passive exoskeleton prototype for the relief of knee-load employing ischiatic body weight support. Methods and materials: A functional prototype was developed and tested with three volunteers to analyze its potential effectiveness and effects on gait kinematics. The performance of the prototype was assessed using motion capture and pressure mapping systems, and a testing bench for the study of ischiatic body weight. Results and discussion: The results of the tests indicate that the prototype allows reducing the load supported by the knees and does not have a significant effect on the kinematics of the hip and knee joints. The process allowed the designers to identify possibilities of improvement mainly on reducing the restrictions imposed by the prototype to the motion of the ankles, especially on the midstance of the support phase. Conclusions: The passive exoskeleton prototype developed for ischiatic body weight support allows setting different percentages of knee-load relief. The prototype does not have a significant effect on the kinematics of the hip and knee joints. Nevertheless, improvements must be performed to reduce the restrictions to the motion of the ankles. Objetivo: el objetivo de este trabajo fue desarrollar un prototipo de exoesqueleto pasivo para el alivio de carga en la rodilla utilizando soporte isquiático del peso. Métodos y materiales: un prototipo funcional fue desarrollado y probado con tres voluntarios para analizar su posible efectividad y efectos en la cinemática de la marcha. El desempeño del prototipo se evaluó utilizando sistemas de captura de movimiento y de mapeo de presión, y un banco de pruebas para el estudio del soporte de peso corporal isquiático. Resultados y discusión: los resultados de las pruebas indican que el prototipo permite reducir la carga soportada por las rodillas sin un efecto significativo en la cinemática de las articulaciones de la cadera y la rodilla. El proceso permitió a los diseñadores identificar posibilidades de mejora principalmente en cuanto a la reducción de las restricciones impuestas por el prototipo al movimiento de los tobillos, especialmente en la mitad de la fase de apoyo. Conclusiones: el prototipo de exoesqueleto pasivo desarrollado para el soporte isquiático del peso permite definir configurar diferentes porcentajes de alivio de carga en la rodilla. El prototipo no tiene un efecto significativo sobre la cinemática de las articulaciones de la cadera y rodilla. Sin embargo, se deben realizar mejoras para reducir las restricciones sobre el movimiento de los tobillos.