Body Seat Research Articles

Improvement of Physical Health of Primary School Students in the Haibo Bay Area

Background and Aim: A healthier population will have a positive impact on the entire community. In recent years, more and more attention has been paid to the physical health of children, but the current physical health of primary school students in the Bay Area is still worrying. Lack of awareness in schools, limited resources, and insufficient attention to physical education are among the major causes of the decline in physical health caused by irregular lifestyles, the increase in electronic products, lack of physical activity and unhealthy eating habits, and the urgent need to implement effective interventions, The aim is to improve the physical health of primary school students in Haibo Bay to ensure that the overall health level of primary school students in Haibo Bay is improved. Thus, the purpose of this study is to find the decline in the physical health of primary school students in Haibu Bay Area, to develop appropriate teaching and training plans to improve the decline in the physical health of primary school students in Haibu Bay Area and to provide reasonable suggestions to improve students' cardiorespiratory endurance, strength, coordination, flexibility, and weight reduction through exercises. Materials and Methods: This study is an experimental study. G*power is used to calculate that the minimum sample size required for the experiment is 40 people (20 men and women each). A total of 80 students (40 men and women each) are recruited for this study. There are 141 students in grade 5. We randomly select 20 male and female students from each class for training as the experimental group (40 people in total), and 20 male and female students from each class as the control group (40 people in total). The experimental group receives systematic teaching training while the control group receives routine training. The data collected before and after the experiment were sorted out and analyzed. SPSSAU statistical software was used to conduct paired sample T-tests for intra-group comparison and paired sample T-tests for inter-group comparison. The statistical results were represented by mean ± standard deviation and the significance level was set as P<0.05, which made the test scores of students more accurate and more conducive to the formulation and implementation of teaching plans. Understand the student's physical condition. Results: (1) Through systematic physical education training, the experimental group of men and women had different degrees of improvement than before the experiment, in which weight, 50 meters, one-minute jump rope, one-minute sit-up, and seat body forward bending were the most obvious, and the control group also had improvement, but compared with the experimental group, the improvement was smaller. (2) After systematic physical training, the scores of physical health tests of both male and female students in the experimental group were significantly improved, indicating that systematic physical training has a positive effect on improving the physical health of primary school students. And (3) After systematic physical training, the physical health scores of both men and women in the experimental group were higher than those of the control group. It shows that the systematic teaching and training method is more effective than the conventional teaching and training method. Conclusion: the systematic physical education training employed in the study yielded notable improvements in various fitness parameters for both male and female primary school students. The experimental group exhibited superior enhancements compared to the control group, highlighting the efficacy of the systematic teaching and training approach. These findings underscore the positive impact of structured physical education programs in enhancing the overall physical health and fitness of young students.

Lightweight simulation design of integrated die-casting body rear wheel cover and seat crossbeam

Lightweight simulation design of integrated die-casting body rear wheel cover and seat crossbeam

Studying mechanical load at body-seat interface during dynamic activities such as wheelchair propulsion: a scoping review

Background The increasing number of wheelchair users and their risk of medical complications such as pressure ulcers (PU) make it important to have a better understanding of their seating characteristics. However, while most studies tackling this issue are based on static measurements, wheelchair users are active in their wheelchairs when performing daily life activities. This suggests the need to assess the mechanical loads at the wheelchair user’s body–seat interface during dynamic activities. Objectives A scoping review was conducted to explore the existing data (shear load and pressure) and highlight significant parameters, relevant conditions and methodological strategies when studying wheelchair users performing a dynamic task. Materials and methods The literature search was performed by applying the PRISMA methodology. Results A total of 11 articles met the inclusion criteria. Differences between static and dynamic data were found in the literature for peak pressure values, pressure distribution and the location of peak pressure. None measured tangential load at the seat/body interface, although two studies measured the shift of the ischial region. A significant impact of the type of pathology has been quantified, showing the need to perform experimental studies on diverse populations. The protocol and the pressure parameters studied were very diverse. Conclusion Further studies carefully choosing interface pressure mapping parameters and investigating a broader range of pathologies are required. Additionally, researchers should focus on finding a way to measure seated tangential load.

Prevalence and determinants of safety equipment use: Analysis from a national dataset of law enforcement officers in the US

This study investigates the rates of law enforcement officers’ (LEOs) consistent use of body armor, seat belts and reflective vests, and the relationship between officer and agency characteristics and the likelihood of consistent use of safety equipment with data from a nationally representative sample of close to 3000 LEOs in the US. Descriptive analyses were conducted to assess the national prevalence of officers’ consistent use of safety equipment. Three separate multivariable logistic regression models were fit to test relationships between the agency and officer characteristics and LEO use for the three types of safety equipment: body armor, seat belts, and reflective vests. Although most agencies had written policies mandating the on-duty use of safety equipment, only two-thirds of the officers reported consistent use of body armor and seat belts, and only one-third reported consistent use of reflective vests. Significant associations were observed between agency and officer characteristics and safety equipment use, illustrating the importance of targeted efforts to improve consistency in LEOs’ safety equipment use.

Anthropometric and Physical Performance Characteristics of Swimmers

Introduction: The study of body measurements and proportions by anthropometry is important for the identification of young talents in swimming. Therefore, the aim of this study was to a) compare the physical performance profile of swimmers on land and in water and b) understand the relationship between anthropometric and physical performance tests. Methods: To this end, 31 anthropometric variables were determined in 6 male (n=3) and female (n=3) swimmers using the International Society for the Advancement of Kinanthropometry (ISAK) protocols and VO2max laboratory tests. Body fractionation (adipose, muscle, bone, residual, and skin tissue masses) was determined using the validated Kerr & Ross five-way fractionation model for body composition. Data analysis included the person correlation coefficient. Results: The swimming performance test was positively strongly correlated with body height, seat height, arm span, shoulder and pelvic width, and arm and leg length (p ≤ 0.001). In conclusion, these studies reveal some potential key anthropometric factors in the performance of active swimmers. These results support the view that while swimmers have unique anthropometric profiles, more successful swimmers tend to have greater arm spans. Conclusion: These results suggest that anthropometric characteristics are important in swimming performance. This study concluded that improvement in swimming performance is strongly related to anthropometric and kinanthropometric profiles.

A Study on Performance Improvement through Quality Improvement of Spring, Seat Body and Piston of Electronic Valve for Pneumatic Control

A Study on Performance Improvement through Quality Improvement of Spring, Seat Body and Piston of Electronic Valve for Pneumatic Control

Optimization Study on the Comfort of Human-Seat Coupling System in the Cab of Construction Machinery

The seat of a construction machinery cab is used as the research object. For the current human-seat coupling system comfort research methods and optimization index deficiencies, the seat body pressure comfort and vibration comfort at the same time optimized. Based on the more specialized Toyota 50 percentile dummy model, a human-seat finite element simulation model is established, and the body pressure distribution and vibration response are simulated and calculated. The transverse and longitudinal pressure distributions of the backrest and seat cushion and the pressure map are used to verify the simulation model’s body pressure comfort evaluation indexes. At the same time, the vibration response test is used to verify the vibration comfort evaluation indexes of the simulation model. The test results show that the accuracy of each evaluation index of the established coupling model is greater than 85%, which can provide model support for the subsequent optimization work. In order to improve the comfort of the seat of construction machinery during operation, the hardness of the upper sponge and lower layer sponge is reduced and increased by 10% and 15%, respectively, on the original seat. The body pressure comfort evaluation indexes of the ischium peak pressure, ischium mean pressure, thigh peak pressure and thigh mean pressure are used to evaluate the improved seat. The proposed optimization scheme is to reduce the hardness of the upper sponge and lower layer sponge of the seat cushion by 10% to improve the seat body pressure comfort. Finally, the evaluation indexes of body pressure comfort and vibration comfort are verified by four subjects in an improved seat, and the cushion pressure of different subjects is reduced while the vibration isolation rate is increased, which shows the rationality of the proposed optimization scheme. In addition, the evaluation results of the improved seat are different for subjects of different body sizes, with the most significant improvement for the subject of greater height and weight. The modeling and comfort evaluation methods adopted in the paper can provide a reference for the design and development of the seat.

Finite Element Methods for Modeling the Pressure Distribution in Human Body–Seat Interactions: A Systematic Review

The objective of this systematic review is to investigate the various approaches that have been undertaken in finite element analysis (FEA) of human–seat interactions and synthesize the existing knowledge. With advances in numerical simulation and digital human modeling, FEA has emerged as a powerful tool to study seating comfort and discomfort. FEA employs various biomechanical factors to predict the contact stress and pressure distribution in a particular seat design. Given the complexity of human–seat interaction, several modeling and processing steps are required to conduct realistic FEA. The steps of how to perform an FEA simulation on human–seat interactions, the different models used, the model mesh compositions, and the material properties are discussed and reviewed in this paper. This can be used as a guideline for future studies in the context of FEA of human–seat interactions.

Three-Dimensional Biomechanical Modeling for Sitting Contact Stress Analysis.

This paper proposes a three-dimensional biomechanical model of the upper body and analyzes the interaction between the upper body and aircraft seat backrest for different sitting postures and backrest recline angles. The reclined sitting postures of the upper body are defined based on the available spine biomechanical data and the multibody inverse kinematics method. The contact loadings on each contacted spine segment are calculated based on the Newton-Euler dynamic formulation. The backrest contact pressure distribution is simulated using the contact stress theory based on the calculated forces on the backrest. The resultant force and pressure distribution show how the backrest inclination and lateral bending of the trunk affect the backrest loading and contact condition. The simulation results are compared to the experimental measurement for validation, and a good correspondence is found. The parameters, including the average and maximum pressure, and pressure standard deviation based on the pressure distribution, are also compared, and the maximum simulation error is 11.5% on the average pressure. Limitations of the model are discussed. The model proposed in this paper can analyze more posture cases than previous studies that focused on the two-dimensional scenarios. The loading and pressure prediction model can be applied for backrest design evaluation and facilitate seat design optimization.

Posture Estimation Using Surface Electromyography during Wheelchair Hand-Rim Operations.

This study examined competitive wheelchairs that facilitate sports participation. They can be moved straight ahead using only one arm. Our designed and developed competitive wheel-chairs have a dual hand-rim system. Their two hand-rims, attached to a drive wheel on one side, can be operated simultaneously for straight-ahead movement. Specifically, based on integrated electromyography (iEMG) data calculated from surface electromyography (sEMG), we examined the wheelchair loading characteristics, posture estimation, and effects on body posture during one-arm propulsion movement. The first experiment yielded insights into arm and shoulder-joint muscle activation from iEMG results obtained for two-hand propulsion and dual hand-rim system propulsion. Results suggest that muscle activation of one arm can produce equal propulsive force to that produced by two arms. The second experiment estimated the movement posture from iEMG during one-arm wheelchair propulsion. The external oblique abdominis is particularly important for one-arm wheelchair propulsion. The iEMG posture estimation validity was verified based on changes in the user body axis and seat pressure distribution. In conclusion, as confirmed by iEMG, which is useful to estimate posture during movement, one-arm wheelchair use requires different muscle activation sites and posture than when using two arms.

Preliminary analysis of vibration characteristics of human body on high-speed train

To study the ride comfort of high-speed train passengers, a detailed human body–seat–vehicle–track coupled model is developed. This model adopts a dual-axis human-body dynamic model and considers the nonlinearity of the primary and secondary suspensions and the wheel–rail contact condition. Additionally, the input wheel/rail irregularity excitation data are measured for a high-speed railway line in China. According to the model, the root-mean-square (RMS) values of the acceleration for the passenger head at different positions of the car body are determined, and the effects of the car-body loading conditions, speed, and seat support parameters on the head vibration characteristics are studied. The results indicate that the RMS value is the highest for the passengers sitting in the front row near the window seat, followed by those sitting in the middle row of the car body. There are small differences in the RMS value between the passengers sitting on the left and right sides of the same row in the car body. At a certain speed, the track irregularity stimulates the rolling and pitching motions of the train. Therefore, effective methods should be implemented to avoid the inherent characteristics of the car body. Although an increase in the seat support stiffness intensifies the high-frequency vibration, it reduces the low-frequency vibration in the range of 0–15 Hz, reducing the RMS value of the head acceleration. When the train is loaded, the effect of passengers on the car body is similar to that of a damper or mass element, which can reduce the car-body vibration and enhance the ride comfort.

Wear and Deformation of Nozzle Body Seat of Diesel Fuel Injector

Wear and Deformation of Nozzle Body Seat of Diesel Fuel Injector

Analytical and Numerical Investigations of Mechanical Vibration in the Vertical Direction of a Human Body in a Driving Vehicle using Biomechanical Vibration Model

The main reason that affects the discomfort in a driving vehicle is the vibration response. The human body vibration leads to many malfunctions in both comfort and performance in human health. As a result, the human body’s simulation in sitting posture in the driving vehicle has a strategic relationship for all Tires and vehicles manufacturers. The digital process simulation of the human body seat vehicle vibration shows two significant advantages. The first advantage is the prevention of the high-cost modifications in the construction stage of the vehicle, while the second one describes the stability test during the undesirable vibrations. This study modelled the human body’s dynamic characterisations, natural frequency, and mechanical response when seated in the driving vehicle with vibration transmissibility in the vertical direction have been using the biomechanical vibration model. The vertical vibrations and the transmissibility of the human body dynamic response are presented in detail. Exciting results have been obtained, and they are significant for human health, which relates to sitting posture in the driving vehicle. It can assist in understanding the influences of low-frequency vibration on human health, comfort, and performance, and therefore it could be applied for ride comfort evaluation. An analytical solution to derive the general equations of motion for the human system was developed. Then, using the vibration analysis technique and the corresponding equations, the accurate dynamic response of the selected mode is identified. Furthermore, the mathematical modelling for free vibration using the finite element analysis has been performed to determine the appropriate values and set its description. Then, the comparison results of the two techniques have been carried out.

Numerical Study on Natural Ventilation around a Burning Car inside a Tunnel

This study aimed to analyse the flow and temperature fields around a car on fire inside a medium-size tunnel under natural ventilation. The study used the fire dynamics simulator (FDS), which is an open-source software package, to simulate the thermo-fluidic characteristics inside the tunnel. A constant heat release rate (HRR) was assumed to ensure the release of consistent heat from the car while varying the speed of the mass flux natural ventilation. A medium-size tunnel and scaled car were modelled to simulate a realistic field environment; the car was assumed to have its primary components, including the body frame, tyres, seats, and other flammable materials. The constant HRR was set at 3.8 , which was measured in a field experiment using a cone calorimeter. The closed car windows were set to break when the temperature around them reached 600°C. Additionally, natural ventilation was one of the parameters used in the calculation; it was assigned as an inlet condition, referred to as the steady longitudinal inlet velocity, and ranged from 1.8 to 3.0 m/s. Based on the ventilation velocities, the variations of the flow characteristics, temperature field, turbulence kinetic energy levels, and vortex structure inside the tunnel were investigated. Additionally, the critical longitudinal velocity for natural ventilation was estimated by performing the current simulation under different ventilation velocities. Given that the thermo-fluidic parameters and geometry information are all similar, the FDS results were compared to those from three semi-empirical models for predicting critical ventilation velocities from previous studies.

Improvement of Ride Comfort Quality for an Earth-Moving machinery with Semi-Active Cab Isolation System

Improving ride comfort of earth-moving machinery is important to avoid potential health hazards for machine operator. A vehicle - road coupled interaction model including vehicle body, cab body and driver seat masses is set up under the random excitation of ground surface and a Fuzzy –PID controller is designed for control of the damping coefficient of a semi-active hydraulic cab isolation system (SHCIs) for an earth-moving machinery. The ride performance of SHCIs with a combined controller is evaluated under different movement conditions. The comparison results indicate that the proposed controller for semi-active cab hydraulic isolation system has the significantly improved vehicle ride comfort in compared with passive hydraulic cab isolation system (PHCIs) under large amplitude and low frequency excitations of ground surface.

Review of Measuring Microenvironmental Changes at the Body-Seat Interface and the Relationship between Object Measurement and Subjective Evaluation.

Being seated has increasingly pervaded both working and leisure lifestyles, with development of more comfortable seating surfaces dependent on feedback from subjective questionnaires and design aesthetics. As a consequence, research has become focused on how to objectively resolve factors that might underpin comfort and discomfort. This review summarizes objective methods of measuring the microenvironmental changes at the body–seat interface and examines the relationship between objective measurement and subjective sensation. From the perspective of physical parameters, pressure detection accounted for nearly two thirds (37/54) of the publications, followed by microclimatic information (temperature and relative humidity: 18/54): it is to be noted that one article included both microclimate and pressure measurements and was placed into both categories. In fact, accumulated temperature and relative humidity at the body–seat interface have similarly negative effects on prolonged sitting to that of unrelieved pressure. Another interesting finding was the correlation between objective measurement and subjective evaluation; however, the validity of this may be called into question because of the differences in experiment design between studies.

Fluid Leakage in Metallic Seals

Metallic seals are crucial machine elements in many important applications, e.g., in ultrahigh vacuum systems. Due to the high elastic modulus of metals, and the surface roughness which exists on all solid surfaces, if no plastic deformation would occur one expects in most cases large fluid flow channels between the contacting metallic bodies, and large fluid leakage. However, in most applications plastic deformation occurs, at least at the asperity level, which allows the surfaces to approach each other to such an extent that fluid leakage often can be neglected. In this study, we present an experimental set-up for studying the fluid leakage in metallic seals. We study the water leakage between a steel sphere and a steel body (seat) with a conical surface. The experimental results are found to be in good quantitative agreement with a (fitting-parameter-free) theoretical model. The theory predicts that the plastic deformations reduce the leak-rate by a factor approx 8.

Modeling of impact of the poppet element on its seat body in pressure relief valves

This article deals with modeling of the impact between the moving elements and their seats bodies in pressure relief valves. Four different impact models, such as the Kelvin–Voigt, the Maxwell, the standard-solid and the Hunt–Crossley models, are considered. A comprehensive dynamic model of the studied valve, considering the four models, is deduced. The simulation results show that the Kelvin–Voigt model cannot be used to represent the impact in pressure relief valves because, by the end of impact period, the model results in a tensile force, which is physically impossible in rigid bodies impacting. In the Maxwell model, a considerable number of discontinuities appeared in the impact force, which causes the poppet element to make a number of rebounds with the seat body during the impact period. However, in the standard-solid model, the poppet element barely rebounds. In the Hunt–Crossley nonlinear model, a certain penetration distance between the poppet element and the seat body occurs, which is certainly unrealistic in rigid bodies impacting. The validation of the impact models showed that the Maxwell model is the suitable impact model that can be used to represent the impact in pressure relief valves. However, the validation of the proposed dynamic model proved that the impact has no significant effect on the dynamic performance of pressure relief valves. The main reason behind this is that the impact occurs when the operating pressure has fallen down (the valve is out of operation).

Analysis of Body Slip and Seat Pressure in Powered Wheelchairs with Two-Slide Recline System

Recline and tilt functions are the most desirable features for relieving seating pressure to decrease the risk of pressure ulcers. This study presents a new recline mechanism for a powered wheelchair for users sitting for a long duration. We analyzed the effect of a developed two-slide mechanism. In this study, body slip distance and buttock pressure were measured during wheelchair reclining and repositioning using a three-dimensional motion analysis and a pressure measurement system in 10 healthy subjects. Non-slide, one-slide, and two-slide versions were compared. During reclining, the total slip distance along the backrest with two slides was 40.6 mm, which was 77% and 44% smaller than non-slide and one-slide backrests, respectively. The slip variation of the non-slide was 38 mm at the beginning of recline in the initial seated position, and the slip distance tended to decrease as the recline angle increased. However, in the two-slide backrest, the average slip distance per 10° interval was only 5.1 ± 1.1 mm. In addition, we observed a similar slip in repositioning as in reclining, and the slip distance along the seat also decreased most in the two-slide backrest. The buttock pressure gradually decreased from 100° to 150° and then increased again from 160°, but the two-slide backrest showed a tendency to decrease at larger angles of recline and decreased by 59% of the maximum pressure. This study confirms that the two-slide system reduces body slip and buttock pressure, and it is expected that risk factors caused by the long-term use of a wheelchair can be minimized.

Increasing the Comfort of the Harianavi Bullocks by Reduction of Contact Pressure on Neck by Designing a Body Contoured Yoke

ABSTRACT A yoke is an interface between bullock power and actual work to be performed. The yoke is worn on the neck of the bullocks and is secured by a belt around the neck. The bullocks push the yoke with their shoulders, hump and neck; therefore, the work is performed. Neck of the bullock is subjected to a high pressure which damages the body tissues. Consequently, bullocks are subjected to injuries, pain and fatigue that limit their performance. The neck seats are shaped similar to the neck profile of the bullocks which ensures high contact area between animal body and neck seat leading to lesser pressure and more animal comfort. The neck of a bullock was digitized using an optical scanner and a large number of points were obtained. The 3-D model was created on the digitized points, and the neck seat was developed subsequently. The contact analysis was performed using the augmented Lagrangian formulation option of Ansys Workbench for predicting contact pressure. The results of the body contoured yoke are compared with that of a flat wooden plank yoke and a cylindrical yoke. A substantial reduction of contact pressure and indentation on the neck has been found for the body contoured yoke. Conversely, the contact pressure was found much higher for other two types of yokes.