Jordi Vinolas

Existing thermoacoustic dynamic measurement instrumentation is typically expensive and relies on proprietary designs, sensors, and acquisition equipment. However, this study presents a low-cost acquisition solution for sampling pressure and calculating instantaneous power measurements from a thermoacoustic engine using cost-effective sensors and control boards based on the Arduino platform. While the platform was designed for thermoacoustic engines with extra security for safe, high-speed data transfer, it could also suit other applications with similar needs. This study details the implementation of the sampling system and sensor arrangement, employing Python 3.10.2 algorithms based on the two-pressure sensor method to process and present the data. The sampling system is evaluated against a high-performance sound acquisition system. The accuracy of the low-cost system is found to be satisfactory for expected thermoacoustic experimental conditions in terms of pressure resolution and accuracy, with no data loss. These results allow for significantly increased accuracy at low cost in determining the maximum power extracted from any thermoacoustic device.

We present here experimental verification of a theoretical model previously developed to estimate internal mechanical stress in steel-based elements by means of non-contact electromagnetic induction measurements. Results confirm the validity of the proposed model and demonstrate that stress below 50% of the elastic limit can be detected with standard electronics.

In recent years, both the manufacture and sales of electric vehicles have significantly grown compared to traditional vehicles. This growth has favored the creation of tools that measure and evaluate this class of vehicles’ mechanical and electrical operation quickly, simply, and efficiently. Nevertheless, the measurement of electric-vehicle parameters can be a challenge due to the fact that the required DAQ equipment is expensive and thus of limited availability. This work describes a low-cost data acquisition system to simplify and reduce the cost of measuring the current and voltage parameters of electric vehicles. The proposed system is based on a Raspberry PI 3b+ microcomputer and it was evaluated during different driving cycles. The results were compared with the data obtained using a professional Dewesoft Sirius system for validation. The Raspberry Pi-based low-cost system achieved comparable performance to commercial systems (with a measurement error of less than 1%), despite having a lower sampling rate. Furthermore, unlike other systems, the proposed platform is an easy-to-set universal solution that can store the measured data, display them in real-time, graph them, and export the information for analysis with other specialized statistical tools. The main contribution of this work lies in the fact that the proposed low-cost DAQ system can be easily cloned, and the components cost of the prototype is about 10 times less than the price of the commercial systems.

The equations governing energy conversion in traveling wave thermoacoustic machines are affected by their multiphysics nature. Their theoretical study is complicated and, in order to obtain real results, it is necessary to resort to prototypes and experimental tests. This work presents the theoretical–experimental study of a thermoacoustic Stirling engine in which, by altering some of its critical parts and analysing the experimental result, it is possible to improve its performance. The methodology used is based on the study and modelling of the active and reactive acoustic power flow for the improvement of the output power of the thermoacoustic engine. The work and analysis are illustrated through the instrumentation of a thermoacoustic Stirling engine with three different feedbacks. The present work presents the experimental results obtained in all cases, including their parameters, experimental data and analysis. The results are compared with the virtual computational models, allowing us to quantify the theoretical/experimental correlation and the performance improvement obtained that allows us to significantly increase the energy provided by the thermoacoustic machine. In conclusion, it is shown that the proposed methodology is a useful design tool that allows using a simplified and practical approach in the study of the power flow of thermoacoustic machines.

This article presents an innovative energy recovery shock absorber system for motorcycles. The shock absorber is named synchronous pulley - energy harvesting shock absorber (SP-EHSA). The SP-EHSA is the first system specifically designed to maximize the energy recovery of motorcycles without compromising their dynamic behavior. Throughout the article, the theoretical design, computer modeling, optimization, design, and testing of the system are presented. The article results in a validated computer model of the SP-EHSA shock absorber. The validation is done by manufacturing and testing a physical prototype on a test bench. A study of the energy recovery potential for different road profiles at speeds between 20 and 100 km/h was carried out, obtaining in a typical type B road at 60 km/h an estimated 19.68 W average power. Finally, the effect of energy management (i.e., battery's state of charge) on the dynamic behavior of the vehicle is analyzed.

We present a non-invasive method of detecting stress below the elastic limit in magnetic steel elements. The method, based on well-known magnetoelastic effects, relies on mechanical stress-induced permeability modulation. It does not measure absolute values and hence results in suitable in situ measurements in situations where small position or vibration changes can change absolute values.

We present a non-invasive method of detecting stress below the elastic limit in magnetic steel elements. The method, based on well-known magnetoelastic effects, relies on mechanical stress-induced permeability modulation. It does not measure absolute values and hence results in suitable in situ measurements in situations where small position or vibration changes can change absolute values.

The demand for power is increasing due to the rapid growth of the population. Therefore, energy harvesting (EH) from ambient sources has become popular. The reduction of power consumption in modern wireless systems provides a basis for the replacement of batteries with the electromagnetic energy harvesting (EMEH) approach. This study presents a general review of the EMEH techniques for autonomous sensor (ATS) applications. Electromagnetic devices show great potential when used to power such ATS technologies or convert mechanical energy to electrical energy. As its power source, this stage harvests ambient energy and features a self-starting and self-powered process without the use of batteries. Therefore, it consumes low power and is highly stable for harvesting energy from the environment with low ambient energy sources. The review highlights EMEH circuits, low power EMEH devices, power electronic converters, and controllers utilized in numerous applications, and described their impacts on energy conservation, benefits, and limitation. This study ultimately aims to suggest a smart, low-voltage electronic circuit for a low-power sensor that harvests electromagnetic energy. This review also focuses on various issues and suggestions of future EMEH for low power autonomous sensors.

This paper explores the possibility to measure changes in internal stress in ferromagnetic steels using magnetostatic methods. The device consists of a permanent magnet placed close to the steel piece and a magnetic probe between both elements. The magnetostatic field measured by using the probe is partially due to the magnetization of the steel piece. Internal stress variations in the steel alter its magnetic permeability due to the magnetoelastic effect, varying the magnetostatic field measured by using the probe. For the device we present here, the relative variation of the measured magnetic field is of the order of 1.7 × 10⁻⁵/MPa of internal stress.