Increasing Tilt Angle Research Articles

Understanding the biomechanics of smartphone addiction: The physical and cognitive impacts of prolonged device use on college students

The widespread use of smartphones, particularly among college students, has raised concerns about the negative impacts of prolonged device use on physical and cognitive health. While smartphones offer many conveniences, excessive usage can lead to a range of biomechanical and psychological issues, including posture-related strain, repetitive strain injuries (RSIs), eye strain, impaired cognitive function, and elevated levels of anxiety and stress. This study aims to examine the physical and cognitive impacts of prolonged smartphone use among college students, focusing on biomechanical strain, cognitive impairments, and psychological effects. It explores the relationship between smartphone addiction and its effects on posture, musculoskeletal health, eye fatigue, focus, memory retention, and mental health. The study was conducted with a sample of 37 college students in China. Data collection involved physical assessments, including posture analysis, musculoskeletal screening, and cognitive assessments, such as focus and memory tests. Mental health was evaluated using standardized surveys for anxiety, stress, and depression. Statistical analyses were used to interpret the data, including descriptive statistics, paired t-tests, correlation analysis, and multiple regression. The results indicated a significant increase in neck tilt angle, posture discomfort, and wrist strain over the study period, with higher smartphone usage correlating with worse physical outcomes. Cognitive performance, mainly focuses and memory retention, significantly declined with increased smartphone usage. In addition, elevated levels of anxiety and stress were observed among heavy smartphone users, with a strong correlation between high smartphone usage and negative psychological effects.

Preparation and initial condensation characteristics of superhydrophobic coating based on nano-SiO2 particles

Superhydrophobic surfaces can effectively inhibit the growth of droplets and reduce attachment, thus inhibiting the formation of frost. In this paper, using dimethyldimethoxysilane-modified silica nanoparticles, a superhydrophobic coating with a contact angle of 165.73 ± 1° and a rolling angle of 2 ± 1° was successfully prepared by the secondary spraying method, and the chemical composition of the substrate and the surface morphology of the coating were characterized by means of FT-IR, EDS, and SEM. A visualization test rig was constructed to investigate the condensation droplet growth characteristics on the superhydrophobic surface across various tilt angles (0°to 90°), cold surface temperatures (-1 ℃ to 5 ℃), and humidity levels (45% to 75%). The experimental results revealed that as the tilt angle increases, the forces acting on the condensed droplets change, resulting in a higher frequency of droplet merging, jumping, and slipping. Furthermore, a decrease in cold surface temperature accelerates the growth of condensed droplets. Under varying humidity conditions, droplets on the superhydrophobic surface nucleate and grow more rapidly in high humidity environments, where they exhibit a larger coverage area despite having a relatively small mean radius.

Dust deposition characteristics on photovoltaic arrays investigated through wind tunnel experiments

Optimizing the installation parameters of photovoltaic panels in a photovoltaic array to reduce dust accumulation, thereby enhancing their power generation, is a crucial research topic in the construction of solar power stations in desert regions. Utilizing a series of wind tunnel experiments on a photovoltaic array comprising four equally sized panels, this study assessed how variations in tilt angle, mounting height, spacing, and incoming flow direction influence both the accumulation mass of dust and the particle size distribution in a photovoltaic array. The results indicate that the dust accumulation on the first panel exponential growth with increasing tilt angle, incoming flow angles, and height, while subsequent panels displayed a trend of initial increase followed by a decrease, with a maximum increasing ratio achieved at specific installation configurations, the difference of dust mass on each panel can even be several times. Notably, when the spacing between panels exceeds twice the panel height, the mutual influence on dust deposition becomes negligible, providing a quantifiable threshold for optimal panel spacing. Additionally, significant differences exist in the particle size characteristics of dust in the panel of the array, influenced by the installation parameters of panels and the direction of the incoming flow. This research not only enhances the understanding of dust accumulation in solar energy systems but also offers practical recommendations for optimizing installation strategies, thereby improving the economic viability of solar power stations, particularly in desert regions.

Thermofluidics in Water-in-Glass Evacuated-Tube Solar Collectors Analysis Based on the Symmetry Conditions of Heat Flux and Tilt Angle

This research aims to determine the primary thermofluidic correlations describing the thermosiphon effect under idealized steady-state conditions, considering water-in-glass evacuated-tube geometry, tilt angle, and heat flux. A numerical model based on Computational Fluid Dynamics (CFD) was developed to obtain these correlations for water-in-glass evacuated-tube solar collectors. Initial validation against experimental velocity and temperature profiles was necessary. With a validated CFD model, thermofluidic correlations were determined, expressed as dimensionless parameters such as Re, Gr, and Pr, water-in-glass evacuated-tube dimensions, and tilt angle. Symmetry was exploited in the water-in-glass evacuated-tube geometry for both validation simulations and the development of thermofluidic correlations. Contrary to correlations recorded in the literature, the correlations obtained in this study indicate an increase in water flow and a decrease in mean temperature with increasing tilt angle. These correlations are crucial for the energy–exergy balance formulations used in the analysis and design of such thermal systems.

Identification of the factors influencing the liquid sloshing wave height in a sloped bottom tank under horizontal excitation using PCA approach

The dynamic behavior of liquid storage tanks represents a pivotal research area concerning structural safety and reliability. Notably, sloped bottom tanks exhibit heightened sloshing with reduced liquid mass compared to rectangular counterparts. This study adopts a hybrid approach that seamlessly integrates the linear potential-flow theory, renowned for its analytical rigor in fluid dynamics modeling, with principal component analysis (PCA), a potent technique for dimensionality reduction and feature extraction. The hybrid methodology initially employs the linear potential-flow theory to simulate the fundamental fluid dynamics within sloped bottom tanks subjected to horizontal excitation. Subsequently, PCA is applied to the simulated data, identifying key components of liquid sloshing wave height variations. Through the analysis of these principal components, an accurate model of the maximum sloshing wave height is derived, achieving a close correlation with ANSYS simulation results, exhibiting a correlation coefficient of 0.98 and a mean absolute error of 2.5%. This approach uniquely facilitates the evaluation of the intricate interplay between multiple factors, including tank geometry and excitation frequency, on the dynamic characteristics of liquid sloshing waves in sloped bottom tanks. The findings emphasize the significant influence of tank height and tilt angle, with a sensitivity analysis indicating a 4.07% increase in maximum wave height per degree increase in tilt angle under specified experimental conditions. This comprehensive methodology not only enhances understanding of the complex liquid sloshing phenomenon but also provides precise theoretical and practical guidance for fluid sway control strategies. Future investigations will further expand the scope and elucidate the fundamental mechanisms governing liquid sloshing dynamics.

Study on the Stability of Unbalanced Rotation of Large-Tonnage T-Shaped Rigid Frame Bridges

In the design of cantilever method bridge anti-overturning structures, the appropriate gap between the supporting foot and the lower rotating table is a crucial factor. It affects the distribution of the upper load and the friction force of the rotating structure, playing a key role in stability control. Currently, a reasonably defined range for this gap based on engineering practice has not been established. This study, set against the backdrop of practical engineering for large-tonnage rotational bridges, analyzes potential overturning instability forms during rotation. It provides a detailed examination of the stability performance of bridges in unbalanced states under single-side joint support configurations and analyzes the mechanical performance and stability under different gaps and impact velocities during rotation. The result is that the impact acceleration, angular acceleration of rotation, and tilt angle (gap) increase displacement and stress in the support system, posing a significant safety risk. The present research demonstrates the safety and rationality of the proposed unbalanced rotation and provides control limits for tilt angle and rotation acceleration during the rotation process. These results demonstrate that the proposed support mode ensures safety requirements during unbalanced rotation, offering insights for the design and construction of large-tonnage rotational bridges.

Increased anterior pelvic tilt angle elevates the risk of hamstring injuries in soccer player

ABSTRACT Objective This study aims to determine the impact of increased anterior pelvic tilt angle on hamstring muscle injuries in football players. An independent t-test was performed to compare right and left anterior pelvic tilt angles. Design The study was conducted by monitoring 76 different players from a professional club in the Premier Division of Professional Football League over a period of five years. During this time, the hamstring injuries sustained by the players and their severity were recorded using MRI imaging techniques. Result The comparison of the right and left anterior pelvic tilt angles among players was analysed using an independent t-test for independent groups. The Receiver Operating Characteristic (ROC) analysis was used to determine the threshold value that categorizes the right and left angles. According to the results, a significant impact of the variation in right-left anterior pelvic tilt angle on hamstring muscle injuries was observed (p < 0.05). However, no significant effects were found for the Q angle, tibial torsion, or knee posture (p > 0.05). Conclusion In conclusion, it can be stated that an increase in the anterior pelvic tilt angle is associated with a higher frequency of hamstring injuries.

Experimental investigation on wind loads and wind-induced responses of large-span flexible photovoltaic support structure

Experimental investigation on wind loads and wind-induced responses of large-span flexible photovoltaic support structure

A Review of the Building Heating System Integrated with the Heat Pipe

The heat pipe (HP) is widely applied in the thermal management field at present. In order to make use of the low-grade and renewable energies to maintain building thermal comfort in the heating season, more and more studies with respect to improving the thermal performance of the building heating system integrated with the HP (BHSIHP), such as the floor heating system integrated with the HP (FHSIHP), the thermal storage wall heating system integrated with the HP (TSWIHP), conventional wall integrated with the HP (WIHP) and radiator heating system integrated with the HP (RHSIHP), are conducted. This paper aims to summarize different types of HPs applied in the building heating system and offers an overview of the thermal performance improvement for the BHSIHP. The thermal response, thermal conductivity, thermal resistance, heat capacity, heat transfer coefficient, temperature distribution, thermal storage and heat release capacity are always selected to investigate characteristics of the BHSIHP. Results show that the thermal performance of the FHSIHP, the TSWIHP, the WIHP and the RHSIHP is more outstanding than that of the conventional heating system. The thermal performance of the BHSIHP is affected by heat source temperature, installation tilt angle, working fluid, and filling ratio of the HP. The heat source temperature, which positively affects the performance of the BHSIHP, is crucial for the selection of the working fluid and filling ratio. However, the performance of the BHSIHP is increased first and then decreased with the increase of the installation tilt angle. The optimal filling ratio of the working fluid has been proven not to be a fixed value.

Self-consistent modelling of radio frequency sheath in 3D with realistic ICRF antennas

Abstract Ion Cyclotron Resonant Frequency (ICRF) induced impurity production has raised many concerns since ITER proposed to change the first wall material from beryllium to tungsten. Enhanced DC plasma potential (VDC) due to RF sheath rectification is well known as one of the most important mechanisms behind the RF induced impurities. Our previous work (L. Lu et.al, Plasma Phys. Control. Fusion 60 (2018) 035003) considered the impact of both the slow wave and the fast wave on the RF sheath rectification in a 2D geometry. It can barely recover the double-hump structure of the VDC poloidal distribution observed in various machines when only the slow wave is modelled using the multi-2D approach which intrinsically assumes the poloidal wavenumber kz is zero. The fast wave on the other hand is found to be more sensitive to a finite kz and may need to be tackled in 3D. This work reports our recent progress on the 3D RF sheath modelling. In this new code, the latest RF sheath boundary conditions (J. R. Myra, J. Plasma Phys. 87 (2021) 905870504) and the realistic 3D ICRF antennas are implemented. Compared to the 2D results, the 3D code could well recover the double-hump poloidal distribution of VDC even with the fast wave included, which confirms our speculation on the necessity of treating the fast wave in 3D. While the double-hump pattern is robust in the simulation, the amplitude of VDC is found to be affected by the magnetic tilt angle and the antenna geometry. This emphasizes the importance of adopting a realistic antenna geometry in the RF sheath modelling. The double-hump VDC poloidal structure breaks as the magnetic tilt angle increases. This is explained by the gyrotropic property of the cold plasma dielectric tensor. The spatial proximity effect we identified in the previous 2D simulations is still valid in 3D. Finally, simulation shows the slow wave dominates the RF sheath excitation in the private SOL, while the fast wave gradually takes over when moving to the far SOL region. This code could be a new tool to provide numerical support for ITER impurity assessment and ICRF antenna design.

Study of ash deposition characteristics of photovoltaic arrays taking into account the effect of photovoltaic module spacing and its effect on output characteristics: Indoor experiment

Study of ash deposition characteristics of photovoltaic arrays taking into account the effect of photovoltaic module spacing and its effect on output characteristics: Indoor experiment

Numerical simulation of dust deposition characteristics of photovoltaic arrays taking into account the effect of the row spacing of photovoltaic modules

Numerical simulation of dust deposition characteristics of photovoltaic arrays taking into account the effect of the row spacing of photovoltaic modules

High-sensitive glucose sensor based on tilted fiber Bragg gratings

High-sensitive glucose sensor based on tilted fiber Bragg gratings

Research of dust removal performance and power output characteristics on photovoltaic panels by longitudinal high-speed airflow

Research of dust removal performance and power output characteristics on photovoltaic panels by longitudinal high-speed airflow

Study of Wind Load Influencing Factors of Flexibly Supported Photovoltaic Panels

Flexible photovoltaic (PV) support structures are limited by the structural system, their tilt angle is generally small, and the effect of various factors on the wind load of flexibly supported PV panels remains unclear. In order to investigate the shape coefficients of the flexibly supported PV panel arrays, the grid-independent validation is carried out first, and then the case study validation is carried out to ensure the accuracy of the method in this paper. The CFD numerical simulation method is used to obtain the wind load variation of the PV panel array with different tilt angles, different spacing ratios, different wind angles, different heights above ground, different regions, and mountainous conditions. The distribution of wind pressure coefficients on the surface of PV panels with different inclination angles at different spacing ratios was investigated. The results show that the wind load shape coefficients with the increase in tilt angle and height above ground are basically a linear growth; the maximum value of PV shape coefficients appears in the wind angle at 30°, and 150° near the different tilt angles of the flexible PV array group shape coefficients distribution law is inconsistent. Different tilt angles of PV modules with the change rule of the spacing ratio of the wind load are inconsistent and have a greater impact on the wind load, so the PV panel array in all wind direction angles under the regional shape coefficients has a recommended value. The proposed value of the regional shape coefficients at all wind angles and the wind load calculation formula introducing height coefficients and spacing ratio coefficients are given.

Aerodynamic and Structural Assessment of Floating Wind Turbine Rotor Under Varying Tilt Angle

Predicting the aerodynamic performance of floating offshore wind turbines (FOWTs) proves challenging due to platform motion induced by waves. The effect of wind and waves results in a six-degree-of-freedom motion of the platform, directly influencing turbine performance. Understanding the impact of specific degrees of freedom (DOF) motions on aerodynamics and structural response is crucial for effective wind turbine design. This research examines the impact of rotor tilt on both aerodynamic performance and structural response. The investigation employs computational fluid dynamics (CFD) analysis and mapping aerodynamic loads onto the finite element (FE) mesh for structural analysis. The study employs a comprehensive 3D simulation, utilizing the moving reference frame (MRF) method for the NREL 5 MW reference wind turbine CFD simulations. It explores different rotor tilt angles (5°, 10°, 15°, and 20°) encountered by offshore structures during their operation and examines their impact on aerodynamic performance. Predicted aerodynamic loads were mapped onto the blade FE mesh using the radial basis function (RBF) interpolation technique and solved using the open-source FE solver CalculiX. The analysis shows that the turbine performance is relatively unaffected up to a tilt angle of 10°. However, further increase in rotor tilt angle adversely impacts turbine performance, leading to notable reductions in thrust and power output. The fluid-structure coupled analysis provided insights into the deformations and stresses experienced by the turbine blade, indicating a notable increase in flap-wise displacement for larger tilt angles, while edge-wise displacement is not as significantly affected. The maximum stress location on the blade generally correlates well with actual observations.

A novel approach of stability and topography prediction in five-axis ball-end milling process through workpiece-edge-coupling

By studying the workpiece-edge-coupling (WEC) in five-axis ball-end milling, the contact characteristics between the workpiece and edge curve are analyzed, and the chip model is extracted and simplified. The edge curve involved in the cutting process of each edge are calculated at each time and a new instantaneous numerical chip thickness model is established. Then the milling forces and stability lobe diagram (SLD) are calculated in following cut process with lead and tilt angle. The milling forces and SLD of lead angle at 15° and tilt angle at −15° are verified by comparing with Otzurk model as references, and it is found the SLD of WEC model can reflect the unstable points more properly than that of Otzurk model. Also the vibration in [Formula: see text] and [Formula: see text] directions show a divergence trend, which proves the high precision for the new algorithm adapted to the stability prediction of five-axis ball-end milling process. In addition, the surface topography is acquired considering lead and tilt angle as well as forced vibration, and the result is consistent with the experiment in the existing literature. It is found that the milling forces, SLD and surface topography show the same variation trend with the increase of lead and tilt angle. Besides, the stability region significantly expands and the surface topography improves by applying positive tilt angle other than the negative. Then, under the conditions of positive lead and tilt angle, increasing lead angle and decreasing tilt angle reduces the milling force, expands the stability region of SLD and improve the surface topography. The optimized tool posture is acquired by the coincident analysis of milling force, SLD and surface topography under different lead and tilt angle.

Experimental Investigation of the Influence of Longitudinal Tilt Angles on the Thermal Performance of a Small-Scale Linear Fresnel Reflector

This paper analyses the influence of the longitudinal tilt angle of the secondary system of a low-concentration photovoltaic system based on a small-scale linear Fresnel reflector. Several evaluation indicators, such as useful heat gain, thermal efficiency, incident solar irradiance gain on the photovoltaic cells, and total useful energy gain, were evaluated for five wind speed conditions and six locations in the Northern Hemisphere. The tests were performed with two small-scale linear Fresnel reflector configurations: the classical large-scale linear Fresnel reflector configuration (base configuration) and the optimal longitudinal tilt angle configuration (longitudinal tilt configuration). An experimental platform based on an open-loop wind tunnel was designed and built for this purpose. As far as useful heat production, the longitudinal tilt configuration performs worse as the longitudinal tilt angle and wind speed increase. A useful heat gain 33.91% lower than the base configuration is obtained with a wind speed of 10.03 (m/s) at the 36.86 (°) latitude location. Thermal efficiency decreases with increasing wind speed and longitudinal tilt angle. The thermal efficiency is between 0.3 and 0.2 with wind speeds of 4.99 (m/s) and 10.03 (m/s). The longitudinal tilt configuration shows the best increase in total useful energy gain in the absence of wind (up to 53% at a latitude of 36.86 (°)). This increase is 25% at this same location with a wind speed of 10.03 (m/s). It can be concluded that the effect of the longitudinal tilt of the secondary system has a positive effect. To highlight the importance of this work, the results obtained in the configuration comparison were used to compare a nonconcentrating photovoltaic system and a low-concentration photovoltaic system. The incident solar irradiance on the photovoltaic cells is much higher with nonconcentrating photovoltaic technology. This solar irradiance gain is over 60% for the base configuration and 45% for the longitudinal tilt configuration. The total useful energy gain is 70% in the absence of wind and at the 36.86 (°) latitude location in favour of the low-concentration photovoltaic system. The nonconcentrating photovoltaic system performs better with a wind speed of 10.03 (m/s).

Numerical study on heat transfer and evaporation vaporization performance of solar assisted heat pump regenerative evaporator based on dual-phase change coupled heat transfer

Numerical study on heat transfer and evaporation vaporization performance of solar assisted heat pump regenerative evaporator based on dual-phase change coupled heat transfer

Study on Temperature Characteristics of Lubrication Film of Valve Plate Pair in Axial Piston Pumps

The film temperature distribution of the valve plate pair in axial piston pumps affects its lubrication, leakage, and friction. In order to investigate the film temperature distribution of the valve plate pair in axial piston pumps, a test platform was constructed including three displacement sensors for the oil film thickness and eleven thermocouples for the film temperature distribution of the valve plate pair. An accurate film shape model of the valve plate pair was built according to the three-point film thickness test data. Based on the film shape model, the film temperature model of the valve plate pair was developed considering the viscous oil temperature characteristics, the energy loss caused by leakage and viscous friction in the film, and the heat conduction among the oil, cylinder block, and valve plate. The influence of different swash plate tilt angles and operating pressures on the valve plate film temperature was studied. The test results indicate that the film temperature of the valve plate pair increases as the working pressure and swash plate tilt angle increase. The theoretical and experimental absolute errors of the film temperature in the circumferential range [−60°, 60°] of the valve plate high-pressure side are less than 3.5 °C. As the swash plate tilt angle varies from 12° to 16° and working pressure from 3 MPa to 7 MPa, the minimum film thickness position and the maximum temperature point move accordingly in the circumferential range [−15°, 5°] of the valve plate pair.