Search Results (7)

Background/Objectives: Health management in workers in the taxi industry is particularly challenging due to irregular working hours and the need to prevent fatal accidents. In addition, drivers in Japan are aging, and the early prevention of age-related deterioration in oral health is an increasingly important issue. The aim of this cross-sectional study was to investigate the relationships between oral diadochokinesis (OD), tongue pressure, and lip-seal strength in Japanese male taxi workers. Methods: Measurements of tongue pressure and lip-seal strength were performed by dentists using specialized equipment. OD was measured using the number of consecutive “Pa”, “Ta”, and “Ka” vocalizations that could be produced in 5 s. We performed multiple regression analysis to examine the effects of lip-seal strength and tongue pressure on OD. Results: The study included 437 participants, excluding 17 who could not complete all oral cavity measurements. Tongue pressure showed a significant positive correlation with “Pa”, “Ta”, and “Ka” (correlation coefficients: 0.527–0.680). Lip-seal strength was not significantly correlated with OD. Tongue pressure showed a significant positive correlation with “Pa”, “Ta”, and “Ka”. In the results of multiple regression analyses without the elderly participants, tongue pressure was associated with “Pa” (β[95% confidence interval]: 0.574[0.304, 0.843]), “Ta” (0.436[0.231, 0.640]), and “Ka” (0.424[0.210, 0.639]), and lip-seal strength was associated with “Pa” (0.128[0.032, 0.224]) and “Ka” (0.083[0.006, 0.160]). Conclusions: OD may be associated with lip-seal strength and tongue pressure even without including elderly workers. Regardless of age, maintaining good OD may help maintain lip-seal strength and tongue pressure, which may play a role in reducing the risk of age-related oral disorders. Full article

With the startup of the aero-engine, the ground vortex is formed between the ground and the engine intake. The ground vortex leads to total pressure and swirl distortion, which reduces the performance of the engine. The inhalation of the dust and debris through a ground vortex can erode the fan blade, block the seals and degrade turbine cooling performance. As the diameter of the modern fan blade becomes larger, the clearance between the intake lip and the ground surface is smaller, which enhances the strength of the ground vortex. Though considerable numerical studies have been conducted with the predictions of the ground vortex, it is noted that the accurate simulation of the ground vortex is still a tough task. This paper presents authors’ simulation work of the ground vortex into an intake model with different crosswind speeds. This paper tackles the challenge with a parametric study to provide useful guidelines on how to obtain a good match with the experimental data. The influence of the mesh density, performance of different turbulence models and how the boundary layer thickness affects the prediction results are conducted and analysed. The detailed structure of the flow field with ground vortex is presented, which can shed light on the experimental observations. A number of suggestions are presented that can pave the road to the accurate flow field simulations with strong vorticities. Full article

This cross-sectional study aimed to examine the relationships between lip seal strength, tongue pressure, and daytime sleepiness in Japanese workers. A self-administered questionnaire which comprised the Epworth Sleepiness Scale (ESS) was completed by 496 workers, and excessive daytime sleepiness was defined by an ESS score of 11 or over. Lip seal strength and tongue pressure were measured in all participants, and multiple regression analyses were performed to examine the effects of lip seal strength and tongue pressure on daytime sleepiness. The median ESS score was 5.0 (25th and 75th percentiles: 2.0 and 8.0), and 42 (8.5%) workers had excessive daytime sleepiness. The median lip seal strength was 13.5 N (11.4, 16.3), and the tongue pressure was 41.7 kPa (35.2, 48.3). Workers with higher ESS scores had significantly lower levels of lip seal strength than those without, following adjustments for age and body mass index (BMI) values (β (95% confidence interval): −0.043 [−0.081, −0.004]). However, tongue pressure was not significantly associated with ESS score after adjustments for age and/or BMI. These results suggest that maintaining moderate lip seal strength may help prevent excessive daytime sleepiness in Japanese workers regardless of age or BMI. Full article

Deep-sea pressure vessels are specialized pressure vessels designed for automatic deployment from underwater to the surface. These vessels find extensive applications in underwater life-saving and transportation. Their interiors are furnished with a pair of sealing rings, one of which is lip-shaped, and the other is a convex shape, to ensure a dependable seal. With increasing water depth, the sealing rings experience augmented pressure, resulting in a gradual pressing of the rings into the sealing groove. Using ANSYS workbench finite element software, a two-dimensional axisymmetric lip seal finite element model using forces for overall constraint was established, the complete process of progressive pressing into the sealing groove was simulated, and the deformation, contact stress, maximum shear stress, and von Mises stress distribution was also simulated. We also conducted a comparative analysis of lip seals under low and high-water pressure sealing conditions. The findings of the study indicate that when subjected to a combined effect of the installation pre-tightening force and the working water pressure, the lip seal experiences complete compression into the sealing groove at a specific water depth. When subjected to the simultaneous influence of water pressure on the sealing ring material and friction force on the contact surface, two extremes of contact stress manifest in the primary sealing zone of the lip seal. These extremes have the capacity to elevate the contact stress and the effective sealing width, ultimately leading to an improvement in the sealing performance. Concurrently, as the water pressure gradually increases, the inner concave circle of the sealing ring experiences stretching, leading to a reduction in stress concentration, equivalent stress, and shear stress to a considerable extent. This mechanism ensures that the lip-shaped sealing ring retains sufficient strength. This study offers a viable solution for conducting sealing studies on deep-sea separable pressure vessels. Full article

Lip seal strength and tongue pressure are related to sarcopenia in older adults and are directly linked to the quality of life of workers after retirement. This study examined lip seal strength and tongue pressure among Japanese male workers by age. A self-administered questionnaire survey including alcohol consumption and smoking was conducted on 454 male workers. Height, weight, lip seal strength, and tongue pressure were also measured and then stratified by age (20s, 30s, 40s, 50s, and 60s and over). The mean (25th, 75th percentiles) lip seal strength and tongue pressure for all workers were 13.7 N (11.6, 16.4) and 41.7 kPa (35.2, 48.2), respectively. Both lip seal strength and tongue pressure were lowest in the 20s, at 12.1 N (9.6, 14.0) and 40.6 kPa (33.4, 47.6), respectively. The multiple regression analysis adjusted for smoking showed a significant positive association between lip seal strength and BMI for the 20s, 50s, and 60s and over, and a significant positive association between tongue pressure and BMI for the 30s, 40s, 50s, and 60s and over. To maintain oral health in older adults, it may be useful to measure workers’ lip seal strength and tongue pressure and intervene at an earlier stage. Full article

The synergistic control of resistance reduction and sealing poses challenges to enhancing the rapid dynamic response ability of servo hydraulic cylinders; the key to solving this problem is effectively controlling the sealing gap value. In this study, a micro-variation between the hydraulic cylinder and the piston based on the disadvantage of conventional seals, constant gap seals, and lip gap seals was constructed; MSMA assist support blocks were designed on the piston to form a gap seal strip; then, the sealing gap value could be changed by controlling the magnetic field intensity. Simultaneously, the effects of magnetic field strength, parts-manufacturing precision, temperature, and hysteresis on the micro-variation in the MSMA were analyzed, and effective solutions were proposed. Finally, experiments on the magnetic field, temperature, and hysteresis were conducted by the measurement system. The results showed that the variable value of the sealing gap with the MSMA is feasible under ideal conditions, and can effectively change the amount of MSMA expansion by controlling the magnetic field strength, temperature, preload, etc., and then change the amount of the sealing gap of the hydraulic cylinder. This is the key to achieving friction and sealing control, which plays a crucial and active role in improving the efficiency of hydraulic systems. However, the impact of hysteresis effects cannot be ignored, which will be the main problem to be solved in the future. Full article

The purpose of this study was to explore the relationship between lip sealing and lip power, and the effect of button pull exercise on lip posture and lip power. 91 patients who had barely acquired lip sealing had received button pull exercise. They were evaluated for lip power and lip seal before and after Oral Myofunctional treatment. In spite of contrary postures of lip between the Button Pull Group and the Non-Button Pull Group no significant difference for lip strength was found at the first examination. The lip strength of the Button Pull Group had increased twice as much after a half-year and decreased thereafter. 25% of the Button Pull Group acquired complete lip sealing after the treatment, 41% did incompletely and 31% did not change. Full article