An appropriate biomechanical model of seated human subjects exposed to whole-body vibration

2021 ◽  
pp. 146441932110394
Author(s):  
Raj Desai ◽  
Anirban Guha ◽  
Pasumarthy Seshu
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Computational Cost ◽  
Biomechanical Model ◽  
Whole Body ◽  
Body Parts ◽  
Lumped Parameter ◽  
Long Duration ◽  
The One ◽  
The Right

Long duration automobile-induced vibration is the cause of many ailments to humans. Predicting and mitigating these vibrations through seat requires a good model of seated human body. A good model is the one that strikes the right balance between modelling difficulty and simulation results accuracy. Increasing the number of body parts which have been separately modelled and increasing the number of ways these parts are connected to each other increase the number of degrees of freedom of the entire model. A number of such models have been reported in the literature. These range from simple lumped parameter models with limited accuracy to advanced models with high computational cost. However, a systematic comparison of these models has not been reported till date. This work creates eight such models ranging from 8 to 26 degrees of freedom and tries to identify the model which strikes the right balance between modelling complexity and results accuracy. A comparison of the models’ prediction with experimental data published in the literature allows the identification of a 12 degree of freedom backrest supported model as optimum for modelling complexity and prediction accuracy.

Segmental vibration transmissibility of seated occupant from lumped parameter models

2011 ◽  
Vol 18 (11) ◽  
pp. 1683-1689 ◽  
Author(s):  
Masilamany Santha Alphin ◽  
Krishnaswamy Sankaranarayanasamy ◽  
Suthangathan Paramashivan Sivapirakasam
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Biomechanical Model ◽  
Dynamic Parameter ◽  
Experimental Results ◽  
Lumped Parameter Model ◽  
Whole Body ◽  
Driving Frequency ◽  
Lumped Parameter ◽  
Lumped Parameter Models

One of the important parameters for the comfort of a seated occupant of a vehicle is the dynamic parameter. The effects of vibration depend on biomechanical characteristics, transmissibility (TR) and apparent mass. The range of input vibration at the seat and TR at the driving frequency will decide the magnitude of the displacement at any point of the human occupant. The most preferred form of biomechanical model for unidirectional whole body vibration is the lumped parameter model. Lumped parameter models are formulated by number of masses depending on the number of degrees-of-freedom (d.f.). The objective of this work is to study the vibration TR by developing the equations of motion (EOM) for different d.f. models for the seated occupant. Then the generated equations of motion for lumped parameter models are solved using the frequency domain technique. In this paper two, four, seven and 11 d.f. models are considered. The TR values are determined by solving the derived parameters using the MATLAB program. The maximum seats to head TR in the case of two, four, seven and 11 d.f. are obtained at the frequency of 2 Hz, 2.5 Hz, 3.15 Hz, and 4 Hz respectively. The TR obtained from models is compared with real time experimental results. The comparison shows a better fit for the TR obtained from the four and seven d.f. models. There is a wide deviation from the TR observed with two and 11 degrees of models when compared with experimental results of the past literature.

scholarly journals Prevalence of Musculoskeletal Disorders among Stone Polishing Workers using Stone Polishing Devices in Unorganized Sector of Guwahati (India)

2020 ◽  
Vol 9 (5) ◽  
pp. 140-142
Keyword(s):  
Whole Body ◽  
Sustained Load ◽  
Entire Body ◽  
Body Parts ◽  
Repetitive Motion ◽  
Long Duration ◽  
Guwahati City ◽  
Postural Load ◽  
Rapid Entire Body Assessment ◽  
Load Handling

Stone polishing is one of the prominent informal sector in India (and world as well), where a large number of stone polisher works for long duration. Stone polishing workers manually operate the polishing machine either in standing or sitting position to carry out polishing activities, and are quite prone to various MSDs (repetitive strain induced) and thereby injuries and accidents. The present research therefore intends to explore the occurrences of WMSDs among the stone-polishing workers, and with utmost attempt to put forward some recommendations regarding corrective measures. Thirty (30) male stone polishing workers were selected from the Guwahati city of Assam. A comprehensive study on discomfort feeling was carried out by the modified Nordic questionnaire which considered the information about work nature and job stress. Rapid Entire Body Assessment (REBA) method was followed to evaluate whole body postural load and risks associated with the job. The finding of the study contributes to the understanding of the working conditions of the stone polishing workers and their physical discomforts at various body parts (mainly the lower back, knees and shoulder) due to awkward posture, repetitive motion, force exertion and sustained load handling during polishing activities. To overcome the problem arisen from aforesaid ergonomic stressors associated with stone-polishing work, ergonomic design intervention pertaining to modification of the equipment / hand tool like handle design, easy manoeuvrability, avoiding hand-holding of weight etc. have been proposed

Weekly Bone Loading Exercise Effects on a Healthy Subjects Strength, Bone Density, and Bone Biomarkers

2021 ◽  
Vol 92 (3) ◽  
pp. 201-206
Author(s):  
Ann Tsung ◽  
Daniel Jupiter ◽  
John Jaquish ◽  
Jean Sibonga
Keyword(s):  
Bone Density ◽  
Healthy Subjects ◽  
Whole Body ◽  
Bone Biomarkers ◽  
Mineral Density ◽  
Long Duration ◽  
Bone Loading ◽  
The Subject ◽  
The One ◽  
Increased Strength

BACKGROUND: Bone density loss affects astronauts in long-duration spaceflight. The OsteoStrong Company has shown increased hip (14.95%) and lumbar (16.6%) area bone mineral density (aBMD) after 6 mo of exercises with their loading devices. The devices were tested on one subject as a pilot study.CASE REPORT: The subject performed 15 min of osteogenic exercises weekly for 24 wk. Total and regional aBMD, BAP (bone formation biomarker), NTX (bone resorption biomarker), forces exerted on devices, and weekly maximum weights lifted were collected. The control data was the subjects own lifting records 1.5 yr prestudy. The subject increased forces exerted on the devices in the upper extremity (97%, 197 to 390 kg; 435 to 859 lb), lower extremity (43%, 767 to 1097 kg; 1690 to 2418 lb), and spinal compression (22%, 275 to 336 kg; 607 to 740 lb). The monthly strength gain rate increased for snatch (2.3 vs. 0.71 kg; 5 vs. 1.56 lb), clean and jerk (2.5 vs. 0.4 kg; 5.5 vs. 0.88 lb), back squat (3.74 vs. 0 kg; 8.25 vs. 0 lb), front squat (2.15 vs. 0.2 kg; 4.75 vs. 0.47 lb), and deadlift (3.97 vs. 1.09 kg; 8.75 vs. 2.4 lb). The BAP increased by 39% (10.4 to 14.5 4 ug L1) and NTX decreased by 41% (13.4 to 7 nmol L1 BME). aBMD increased in the head (6%), arms (4.3%), trunk (6.3%), ribs (3.8%), and pelvis (11%). There were no differences in body weight, legs, spine, and whole-body aBMD on the full-body dual-energy X-ray absorptiometry (DXA). There were no differences in lumbar, hip, and femoral neck aBMD on the regional DXA.DISCUSSION: The osteogenic loading apparatus used for 15 min weekly increased strength for the one individual in this preliminary study. Future studies on astronauts and other healthy populations are necessary.Tsung A, Jupiter D, Jaquish J, Sibonga J. Weekly bone loading exercise effects on a healthy subjects strength, bone density, and bone biomarkers. Aerosp Med Hum Perform. 2021;92(3):201206.

scholarly journals Evidence for Integrated Visual Face and Body Representations in the Anterior Temporal Lobes

2016 ◽  
Vol 28 (8) ◽  
pp. 1178-1193 ◽  
Author(s):  
Bronson B. Harry ◽  
Katja Umla-Runge ◽  
Andrew D. Lawrence ◽  
Kim S. Graham ◽  
Paul E. Downing
Keyword(s):  
Neural Coding ◽  
Temporal Cortex ◽  
Whole Body ◽  
Unexpected Finding ◽  
Body Parts ◽  
Strong Response ◽  
Body Representations ◽  
Temporal Lobes ◽  
Anterior Temporal Lobes ◽  
The Right

Research on visual face perception has revealed a region in the ventral anterior temporal lobes, often referred to as the anterior temporal face patch (ATFP), which responds strongly to images of faces. To date, the selectivity of the ATFP has been examined by contrasting responses to faces against a small selection of categories. Here, we assess the selectivity of the ATFP in humans with a broad range of visual control stimuli to provide a stronger test of face selectivity in this region. In Experiment 1, participants viewed images from 20 stimulus categories in an event-related fMRI design. Faces evoked more activity than all other 19 categories in the left ATFP. In the right ATFP, equally strong responses were observed for both faces and headless bodies. To pursue this unexpected finding, in Experiment 2, we used multivoxel pattern analysis to examine whether the strong response to face and body stimuli reflects a common coding of both classes or instead overlapping but distinct representations. On a voxel-by-voxel basis, face and whole-body responses were significantly positively correlated in the right ATFP, but face and body-part responses were not. This finding suggests that there is shared neural coding of faces and whole bodies in the right ATFP that does not extend to individual body parts. In contrast, the same approach revealed distinct face and body representations in the right fusiform gyrus. These results are indicative of an increasing convergence of distinct sources of person-related perceptual information proceeding from the posterior to the anterior temporal cortex.

Some aspects of the theory of unimolecular gas reactions

1959 ◽  
Vol 250 (1260) ◽  
pp. 121-131 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Nitrous Oxide ◽  
Degrees Of Freedom ◽  
Normal Modes ◽  
Ethyl Chloride ◽  
Nitrogen Pentoxide ◽  
Order Of Magnitude ◽  
Gas Reactions ◽  
The One ◽  
The Right

An examination is made of the experimental data for the low-pressure second-order uni­molecular decompositions of ozone, nitrous oxide, hydrogen peroxide, nitrogen pentoxide, ethane (into two methyl radicals), cyclo propane and ethyl chloride. The rates are considered in the light of the theories of energization due to Hinshelwood, Kassel, and Rice & Rams-perger (H. K. R. R.) on the one hand, and to N. B. Slater on the other. For nitrous oxide, hydrogen peroxide and ethane Slater’s rates of energization are too low by a significant factor, whereas the H. K. R. R. theories can give a satisfactory interpretation. For ozone, nitrogen pentoxide, cyclopropane and ethyl chloride the Slater rates of energization appear to be of the correct order of magnitude, while the H. K. R. R. rates are too high unless one employs fewer degrees of freedom than are actually in the molecule. These results are explained on the hypothesis that Slater’s theory is correct as far as the breakdown of the energized molecule A * is concerned, but is not always correct with regard to the rate of formation of A *. If flow of energy between the normal modes can take place a molecule A' , energized in the H. K. R. R. sense but not having the right distribution of energy to be energized in Slater’s sense, may become an A *. Reasons are advanced for believing that in small molecules the flow of energy will tend to be more rapid than in large ones. A steady-state treatment of the overall process is presented.

scholarly journals The effects of surface compliance on greyhound galloping dynamics

2019 ◽  
Vol 233 (4) ◽  
pp. 1033-1043 ◽  
Author(s):  
Hasti Hayati ◽  
David Eager ◽  
Paul Walker
Keyword(s):  
Degrees Of Freedom ◽  
Surface Composition ◽  
Substrate Surface ◽  
The Body ◽  
Body Parts ◽  
Contributing Factors ◽  
Life Threatening ◽  
Track Surface ◽  
The Right ◽  
Single Support Phase

Greyhounds are the fastest breed of dog and can reach a speed up to 68 km/h. These racing animals sustain unique injuries seldom seen in other breeds of dog. The highest rate of life-threatening injuries in these dogs is hock fracture, mostly of the right hind-leg. One of the main injury contributing factors in this sport is the track surface. There are some studies into the ideal track surface composition for greyhound racing but almost no study has investigated the body–surface interaction. Accordingly, the purpose of this work is to study the effect of surface compliance on the galloping dynamics of greyhounds during the hind-leg single-support phase which is a critical phase in hock injuries. Thus, a three degrees-of-freedom model for the greyhound body and substrate surface is designed using spring-loaded inverted pendulum method. The results showed that forces acting on the hind-leg were substantially affected when the surface compliance altered from the relatively hard (natural grass) to a relatively soft surface (synthetic rubber). The main contribution of this work is designing a mathematical model to predict the dynamics of the hock and the hind-leg as the most vulnerable body parts in greyhounds. Furthermore, this model can be used to optimise the greyhound track surface composition and therefore improve the safety and welfare within the greyhound racing industry.

Common Anatomical and External Coding for Hands and Feet in Tactile Attention: Evidence from Event-related Potentials

2010 ◽  
Vol 22 (1) ◽  
pp. 184-202 ◽  
Author(s):  
Tobias Heed ◽  
Brigitte Röder
Keyword(s):  
Event Related Potentials ◽  
Spatial Distance ◽  
Whole Body ◽  
Body Parts ◽  
Visually Guided ◽  
Tactile Attention ◽  
Tactile Stimuli ◽  
Related Potentials ◽  
The Right ◽  
Hands And Feet

Recent studies have suggested that the location of tactile stimuli is automatically recoded from anatomical into external coordinates, independent of the task requirements. However, research has mainly involved the two hands, which may not be representative for the whole body because they are excessively used for the visually guided manipulation of objects and tools. We recorded event-related potentials (ERPs) while participants received tactile stimuli to the hands and feet, but attended only one limb. The hands were placed near the feet either in an uncrossed or a crossed posture, thus varying the spatial distance of each hand from each foot. Centro-parietal ERPs 100–140 msec poststimulus were more positive when stimulating the anatomically same-side hand while attending a foot. They were also more positive when the Euclidean distance between the stimulated hand and the attended foot was small rather than large. When a foot was stimulated and a hand attended, a similar modulation of foot ERPs was observed for the right foot. To assess the spatial distance between two limbs in space, the external location of both must be known. The present ERP results therefore suggest that not only the hands but also other body parts are remapped into external coordinates. The use of both anatomical and external coordinates may facilitate the control of actions toward tactile events and the choice of the most suitable effector.

scholarly journals The contribution of stimulating multiple body parts simultaneously to the illusion of owning an entire artificial body

2020 ◽  
Author(s):  
Sophie H. O’Kane ◽  
H. Henrik Ehrsson
Keyword(s):  
Onset Time ◽  
Body Part ◽  
Whole Body ◽  
Multisensory Perception ◽  
Entire Body ◽  
Body Ownership ◽  
Body Parts ◽  
The Right ◽  
Three Body ◽  
Full Body

AbstractThe full-body ownership illusion exploits multisensory perception to induce a feeling of ownership for an entire artificial body. Whilst previous research has shown that the synchronous visuotactile stimulation of a single body part is sufficient for illusory ownership over the whole body, the effect of combining multisensory stimulation across multiple body parts remains unknown. Therefore, 48 healthy adults participated in conditions of a full-body ownership illusion involving synchronous or asynchronous visuotactile stimulation to one, two or three body parts simultaneously (2 x 3 design). We developed a novel questionnaire to isolate the sense of ownership of five specific body parts (left leg, right leg, left arm, right arm, and trunk) from the full-body ownership experience and sought not only to test for greater (part and whole) body ownership in synchronous versus asynchronous stimulation, but also, potentially varying degrees of illusion intensity related to the number of body parts stimulated. As expected, illusory full-body ownership and all five body-part ownership ratings were significantly higher following synchronous stimulation (all p values ≤.01). Since non-stimulated body parts also received significantly higher ownership ratings following synchronous stimulation, the results are consistent with an illusion engaging the entire body. We further noted that ownership ratings for the right body parts (often stimulated) were significantly higher than ownership ratings for the left body parts (never stimulated). Regarding explicit feelings of full-body ownership, subjective ratings were not significantly enhanced by increasing the number of synchronously stimulated body parts (synchronicity x number stimulated interaction; p.099). Instead, median ratings indicated a moderate affirmation (+1) of full-body illusory sensation for all three synchronous conditions; a finding mirrored by full-body illusion onset time. The results support the notion that feelings of full-body ownership are mediated by a generalisation from stimulated part(s)-to-whole, supported by processes related to multisensory body perception.

scholarly journals Identification of damping and stiffness parameters of cervical and lumbar spines of supine humans under vertical whole-body vibration

2019 ◽  
Vol 39 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Guandong Qiao ◽  
Salam Rahmatalla
Keyword(s):  
Human Subjects ◽  
Whole Body Vibration ◽  
Human Model ◽  
Whole Body ◽  
Physical Parameters ◽  
Body Vibration ◽  
Potential Applications ◽  
The Time Domain ◽  
The Right ◽  
Stiffness And Damping

This work presents a methodology to estimate the unknown damping and stiffness parameters of supine humans at the cervical and lumbar regions while reducing errors presented in the data. Modal parameters (natural frequencies, damping ratios, and eigenvectors) determined from experiments on 11 supine-human subjects exposed to vertical whole-body vibration were used in an inverse modal problem to solve for physical parameters (stiffness and damping). Due to uncertainty in the error level in the modal data, a methodology is presented to reduce the error by correcting the phase of the eigenvectors. Constraints that preserve the inter-connectivity of the physical stiffness and damping matrices were utilized via semi-definite programming. A four-degree-of-freedom human model, as suggested by the experimental modal analysis, was used for computational and analysis purposes. The resulting damping and stiffness parameters of the cervical and lumbar regions produced the right structure of the stiffness and damping matrices and satisfied the equation of motion. Validation analysis on the predicted acceleration response in the time domain of the human model, using the resulting damping and stiffness parameters, demonstrated characteristics very close to those found by the experiments. This work presents new information with many potential applications to the field of biomechanics.

scholarly journals Running Form Analysis Based on Impact Dynamics: A Minimally Complex Mechanical Model

2018 ◽  
Vol 63 (1) ◽  
pp. 7-15 ◽  
Author(s):  
László Bencsik ◽  
Ambrus Zelei
Keyword(s):  
Degrees Of Freedom ◽  
Biomechanical Model ◽  
Total Body Weight ◽  
The Body ◽  
Body Parts ◽  
Form Analysis ◽  
Biomechanical Models ◽  
Foot Strike ◽  
Low Degrees ◽  
The Impact

Biomechanical models of different complexity are used to understand the dynamics of human running. Low degrees-of-freedom models are appropriate for the prediction of the effect of certain parameter changes. We present a minimally complex biomechanical model which characterizes the effects of foot strike pattern and shank angle on the ground-foot impact intensity, which influences the risk of injuries and energy efficiency.A three segment leg model (thigh, shank and foot) is proposed combined with the mass of the rest of the body parts concentrated in the hip. The ground-foot impact intensity and the absorbed kinetic energy are analyzed using multibody dynamics tools. The impact intensity was discovered in the parameter space of the angle of the thigh, the angle of the shank, the foot strike pattern and the running speed.The results regarding the effect of strike pattern are in coincidence with the literature: forefoot strike implies lower impact intensity and energy absorption than rearfoot strike. However, in contrast of the previous result of a two segment foot model from the related literature, the calculations indicated that the shank angle highly affects the impact intensity: the impact intensity can be reduced by foot touchdown under the hip. We showed that foot and shank cannot be analyzed in itself without considering the thigh and the total body weight, and we also confirmed that the horizontal velocity cannot be neglected when foot impact is analyzed.

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