Fatigued driving threatens the safety of people’s lives and property. Scent countermeasures offer minimal disruption and high efficacy, making them a promising approach. The aim of this study was to explore the application of scent countermeasures in alleviating fatigued driving. This study explored changes in EEG frequency bands (alpha, beta, theta, and gamma) and the activity of EEG metrics (R_(α/β), R_θ/(α+β) and R_{(α+θ)/(α+β)}) in the temporal lobe during driving tasks, selected fatigued driving identifiers, and aided validation by investigating subjective fatigue with the Karolinska Sleepiness Scale (KSS). The EEG indicators all increased, with a significant increase in R_(α/β). R_(α/β) was combined with the KSS to explore the effects of three scents, peppermint, grapefruit, and lavender, on driving fatigue. The subjective questionnaire results indicated that all three scents significantly improved driving fatigue, with significantly lower levels of driving fatigue compared to the control group. The analysis of EEG signals revealed a significant decrease in R_(α/β) after the implementation of scent countermeasures. Moreover, R_(α/β) was found to be lower in all three odor intervention groups compared to the control group. All three scents were found to significantly alleviate driving fatigue. The grapefruit scent had a better timely effect in relieving driving fatigue and the lavender scent had a longer effectiveness. This study provides further exploration for the application of odor interventions to alleviate driving fatigue. This study provides a practical reference for drivers to use odors to avoid fatigue in order to improve road safety.

Vapor compression refrigeration systems account for a substantial share of global electricity consumption in residential and commercial applications, with environmental impacts arising from both energy use and refrigerant leakage. Refrigerant charge optimization offers an economical means of improving system performance without hardware modifications. Oil-free linear compressors mitigate lubricant-induced degradation of heat transfer, yet the combined influence of charge amount on the coefficient of performance (COP) and total equivalent warming impact (TEWI) has not been thoroughly quantified. An experimental investigation was conducted on a vapor compression refrigeration system equipped with an oil-free linear compressor using R134a. The experiments covered refrigerant charges of 220–330 g, piston strokes of 9–12 mm, and pressure ratios of 2.0–3.5. Component-level refrigerant distribution and system performance characteristics were analyzed systematically. The condenser holds 74.7% of the total refrigerant charge at the optimal charge of 280 g. Rising charge reduces superheat and increases subcooling, both of which serve as practical indicators of the charge level. The mass flow rate, cooling capacity, and COP all exhibit characteristic non-monotonic trends. The maximum COP of 4.67 and the maximum cooling capacity of 472.7 W are both achieved at 280 g, which is identified as the optimal operating condition. The oil-free design eliminates lubricant interference and yields a clearly condenser-dominated refrigerant distribution. The TEWI increases by only 3.6% when the charge is raised to 330 g, and this slight environmental drawback is offset by the gain in energy efficiency. A distinct COP reduction is observed at a charge of 220 g. The charge of 280 g achieves the best balance between energy efficiency and lifecycle CO₂ emissions. This work provides quantitative guidance for charge selection in oil-free linear compressor refrigeration systems.

Vapor compression refrigeration systems account for substantial global electricity consumption, and improving compressor efficiency offers significant potential for energy conservation and climate change mitigation. Linear compressor technology, particularly moving magnet configurations, has attracted attention for its oil-free operation and reduced friction losses, yet comprehensive experimental data under realistic refrigeration cycle conditions remain limited. This study experimentally evaluates the operational characteristics and performance of a moving magnet linear compressor integrated into a complete R134a vapor compression refrigeration system. The investigation systematically varies compressor load from 65% to 85% and pressure ratio from 2.0 to 3.5 while maintaining a fixed condenser temperature of 45 °C. Key parameters, including resonant frequency, piston offset, matching capacitance, power input, mass flow rate, motor and volumetric efficiencies, refrigerant mass distribution, cooling capacity, and coefficient of performance (COP) were measured and analyzed. Results indicate that piston offset remains nearly constant under varying compressor loads, fluctuating around 0.39 mm, but increases by 36% as pressure ratio rises from 2.0 to 3.5, necessitating careful pressure ratio control to prevent mechanical interference. Motor efficiency decreases from 87.7% to 82.4% as the compressor load increases, suggesting favorable part-load operation for domestic energy consumption reduction. This potential remains to be verified through long-term cyclic tests and a full annual energy assessment. The condenser consistently stores over 70% of the refrigerant charge, with distribution most sensitive to operating condition changes. Cooling capacity reaches a maximum of 434.6 W at 85% load and a pressure ratio of 2.0, while the COP achieves approximately 4.5 under the same conditions and decreases to 2.4 at a pressure ratio of 3.5. Normalized COP remains relatively stable at approximately 0.33 across the tested conditions. These experimental findings provide a robust baseline for the design, integration, and control of moving magnet linear compressors in energy-efficient refrigeration applications.

This study investigated the effects of geometric and loading conditions on the bending mechanical response and failure modes of polyetheretherketone thin-walled tubes. The tubes with wall thicknesses of 1, 2, and 3 mm were subjected to three-point bending experiments and numerical simulations under different bending spans. Experimental results showed that for the 1 mm-thick tubes, increasing the span from 80 mm to 140 mm led to a 41.62% reduction in the fracture load. Under a bending span of 80 mm, reducing the wall thickness from 3 mm to 1 mm resulted in an 89.22% decrease in fracture load and a 70.51% reduction in the specific energy absorption. These findings indicated that both the fracture load and energy absorption capacity of polyetheretherketone tubes increased with wall thickness but decreased with bending span. Two concurrent deformation modes were observed in polyetheretherketone tubes during three-point bending: localized compressive indentation at the midspan and global bending. The deformation behavior is primarily dominated by wall thickness, indenter shape and diameter, as well as bending span. Specifically, the 1 mm-thick tubes exhibited a typical localized indentation-dominated mode, while the tubes with 2 mm and 3 mm thicknesses underwent a transition from localized indentation to global bending deformation. This study elucidated the bending mechanical response and failure mechanism of polyetheretherketone thin-walled tubes, thereby providing practical support for the lightweight structural design in the transportation industry.