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The integration of liveness detection into biometric systems is crucial for countering spoofing attacks and enhancing security. This study investigates the efficacy of photoplethysmography (PPG) signals, which offer distinct advantages over traditional biometric techniques. PPG signals are non-invasive, inherently contain liveness information that is highly resistant to spoofing, and are cost-efficient, making them a superior alternative for biometric authentication. A comprehensive protocol was established to collect PPG signals from 40 subjects using a custom-built acquisition system. These signals were then transformed into two-dimensional representations through the Gram matrix conversion technique. To analyze and authenticate users, we employed an EfficientNetV2 B0 model integrated with a Long Short-Term Memory (LSTM) network, achieving a remarkable 99% accuracy on the test set. Additionally, the model demonstrated outstanding precision, recall, and F1 scores. The refined model was further validated in real-time identification scenarios, underscoring its effectiveness and robustness for next-generation biometric recognition systems.

In this paper, a unique method for using thermoelectric generators (TEGs) to generate electricity is introduced, a technique that makes use of a cold oil tank and hot exhaust gases from generators. A set of TEGs and an integrated cold oil tank are connected to the diesel generator as part of the suggested design. A pertinent thermal modeling was designed and a thorough parametric study was carried out to show the validity of this innovative concept. The parametric study has demonstrated that when the generator power and the thickness to thermal conductivity ratio of each TEG in the system are increased, the temperature differential in each TEG module and the power produced by the assembly of TEGs both exhibit linear increases. The length of the TEG plate and the height of the exhaust gas duct cause an exponential increase in the temperature differential across each TEG module. The TEG assembly's power output increases linearly with TEG surface length and decreases exponentially with exhaust gas duct height. Using an exhaust gas duct height of 0.05 m, and a TEGs plate length of 1 m, the parametric study showed that power generation of up to 2778 W is feasible under the predetermined circumstances of a diesel generator with an output of 125 kW. When compared to a conventional setup, the new hybrid generator in this scenario may be able to increase power generation by up to 2.22 %.

Utilizing a cooling technique can help prevent overheating, which can have a detrimental impact on the performance of solar panels. Instead of using a water cooling system that requires a pump, an alternative method uses the return air from a Heating, Ventilating, and Air Conditioning (HVAC) system often utilized in industrial settings. An air cooling system that uses the HVAC system's return air was previously recommended by the co-authors of the current study. Using numerical methods, they carried out a feasibility analysis and showed how a variety of parameters, such as the convection coefficient and the flow type (natural or forced), might affect the output power (efficiency) of the system. As a continuation of the previous study, the present study examines two cooling scenarios to further their past findings. Three different configurations for external flow were tested: cooling the upper and lower surfaces of the PV with exhaust air, installing a vortex generator at the leading edge of the lower surface while relying on natural convection for the upper part, and installing a vortex generator on both the upper and lower surfaces. The efficiency of the PV system increases from 11 % to 18 % with an increase in cooling demand from 0 to 160 kW with solar radiation of 500 W/m2. Efficiency was improved by generating turbulent flow at the leading edge of the panel. While using an internal flow on the bottom surface, the system's efficiency increased as the PV module's length increased.

The present work proposes the engagement of relatively cold air exhausted from Heating, Ventilating and Air Conditioning (HVAC) systems, that exist in structures such as residential commercial and industrial, to reduce the PV modules’ operational temperature. To proceed, a thermal resistance model in steady state is developed along with its corresponding iterative procedure and calculations which are carried out for different configurations and scenarios. The thermal modeling was validated by comparing it to experimental measurement found in the literature. It was revealed that the PV modules’ temperature can be reduced with increasing the mass flow rate of the exhaust air. However, the air mass flow rate depends on the cooling load need; which increases with increasing the cooling load. The efficiency of the PV has shown an increase from 11 to 18% when the cooling load increases from 0 to 160 kW for a solar radiation of 500 W/m2. Moreover, there is an optimum height for the exhaust air duct for each cooling load that must be determined.

In the context of a world energy crisis, the only solution to control the situation is in the management of energy. One of the most important management keys is the optimization of electrical components. This article presents a complete numerical and experimental study aiming for the optimization of electrical water heaters for household use. The optimization conceives the minimization of energy consumption simultaneously with the minimization of time to heat water. Firstly, a thermal model well adapted for the case of heaters is constructed and validated experimentally and then a parametric study is conducted covering all the input power, the volume and the external area of the heater. Results are promising, showing significant energy savings are possible with an optimum setting of these parameters, thus presenting a firm tool for the optimization of heaters.