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The biomechanical behavior of dog's duodenum and jejunum were studied and a formulation of the stress-strain relation is presented in this paper. The results obtained indicated that the exponential coefficient a and the incrementa...
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The biomechanical behavior of dog's duodenum and jejunum were studied and a formulation of the stress-strain relation is presented in this paper. The results obtained indicated that the exponential coefficient a and the incremental duodenum of the elastic modulus are both larger than those of the jejunum. It means that the duodenum is more deformable than the jejunum. The experimental results of this work provide basal data for kinematics study of a robotic endoscope.
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Abstract When thinking about Olympic winter sports and watching events on television, people mostly focus on events where the chances of success are high for fellow-countrymen. For example, in the Netherlands speed skating is cons...
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Abstract When thinking about Olympic winter sports and watching events on television, people mostly focus on events where the chances of success are high for fellow-countrymen. For example, in the Netherlands speed skating is considered the main winter sports event. But with Kimberley Bos there is now also a Dutch medal candidate for the Winter Olympics 2022 in the skeleton discipline. Where speed skaters prepare in summer for the winter season with roller skates, Bos trains on an athletics track with a self-built board on wheels as a replacement for the skeleton. British athletes on the other hand can choose the bobsleigh and skeleton push-start track at the University of Bath for their summer preparation. We prepare for the upcoming Winter Olympics 2022 by taking a physics view on advanced sleighing. We show how school physics helps understanding the motion of athletes in bobsleigh and skeleton and increases respect for the athletes’ performance.
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Modem human shoulder function is affected by the evolutionary adaptations that have occurred to ensure survival and prosperity of the species. Robust examination of behavioral shoulder performance and injury risk can be holistical...
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Modem human shoulder function is affected by the evolutionary adaptations that have occurred to ensure survival and prosperity of the species. Robust examination of behavioral shoulder performance and injury risk can be holistically improved through an interdisciplinary approach that integrates anthropology and biomechanics. Coordination of these fields can allow different perspectives to contribute to a more complete interpretation of biomechanics of the modem human shoulder. The purpose of this study was to develop a novel biomechanical and comparative chimpanzee glenohumeral model, designed to parallel an existing human glenohumeral model, and compare predicted musculoskeletal outputs between the two models. The chimpanzee glenohumeral model consists of three modules - an external torque module, a musculoskeletal geometric module and an internal muscle force prediction module. Together. these modules use postural kinematics, subject-specific anthropometrics, a novel shoulder rhythm, glenohumeral stability ratios, hand forces, musculoskeletal geometry and an optimization routine to estimate joint reaction forces and moments, subacromial space dimensions, and muscle and tissue forces. Using static postural data of a horizontal bimanual suspension task, predicted muscle forces and subacromial space were compared between chimpanzees and humans. Compared with chimpanzees, the human model predicted a 2 mm narrower subacromial space, deltoid muscle forces that were often double those of chimpanzees and a strong reliance on infraspinatus and teres minor (60-100% maximal force) over other rotator cuff muscles. These results agree with previous work on inter-species differences that inform basic human rotator cuff function and pathology.
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A closed-form theoretical model for the biomechanical properties of breast tissues under the influence of external pressure is derived and validated. That model is employed in a microwave imaging method that aims at extracting the...
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A closed-form theoretical model for the biomechanical properties of breast tissues under the influence of external pressure is derived and validated. That model is employed in a microwave imaging method that aims at extracting the three-dimensional biomechanical properties of breast. The high contrast in the biomechanical properties between healthy and malignant tissues represents the basis of the presented imaging method. In this method, the breast is inserted in an enclosure that has an array of ultra-wide-band (UWB) antennas embedded in the upper movable plate of the enclosure. Each of those antennas transmits an UWB pulse towards the breast and measure the backscattered pulse before and after compressing the breast by a controlled force applied at the top of the movable plate. A sliding window cross-correlation is used to get a three-dimensional strain image of the breast. As lesion tissue is much stiffer than the normal breast tissues the regions of zero strain indicate areas of suspected tumor.
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The energy harvesting backpack is a promising solution for powering wearable electronic devices by converting biomechanical energy from human motion into electricity. However, the majority of current energy harvesting backpack mod...
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The energy harvesting backpack is a promising solution for powering wearable electronic devices by converting biomechanical energy from human motion into electricity. However, the majority of current energy harvesting backpack models primarily focus on harvester dynamics while neglecting the crucial role of humans as an energy source in the system. Some studies have utilized inverted pendulum models through active control torque and optimization-based methods to investigate human factors in bioenergy harvesting systems, but this is complex for the practical application of biomechanical models. To overcome these issues, a new biomechanical model of the energy harvesting backpack is proposed in this paper. The contribution of this study is not only modeling the cooperative dynamics between backpacks and humans which is easily solvable and comprehensible but also defining multi-indicators for model verification and backpack evaluation. The biomechanical model without load is established based on the D' Alembert principle and empirical gait phase division of 3:1 when it is assumed that the gait parameters remain constant regardless of the load being carried. Four sets of data from two distinct databases are utilized to analyze the dynamics of the bipedal walking model in both vertical and horizontal directions. The biomechanical model with energy harvesting backpacks is proposed to define four single direct indicators and two global indirect indicators for demonstrating the proposed model's ability to predict the characteristics of backpacks. Finally, the foot-reaction force, the vibration of the center of mass, and the output power of three subjects are acquired in five experiments (ⅰ) with no backpack under variable walking speed; (ⅱ) an ordinary backpack under variable walking speed; (ⅲ) an ordinary backpack under variable loads; (ⅳ) an energy harvesting backpack under variable walking speed; and (ⅴ) an energy harvesting backpack under variable loads. The comparison between the proposed model and experimental results demonstrates that the proposed model is easy to solve and comprehend, and can effectively capture the characteristics of both human and energy harvesting backpacks.
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Objective: The quantification of inter-segmental spine joint reaction forces during common workplace physical demands. Background: Many spine reaction force models have focused on the L5/S1 or L4/L5 joints to quantify the vertebra...
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Objective: The quantification of inter-segmental spine joint reaction forces during common workplace physical demands. Background: Many spine reaction force models have focused on the L5/S1 or L4/L5 joints to quantify the vertebral joint reaction forces. However, the L5/S1 or L4/L5 approach neglects most of the intervertebral joints. Methods: The current study presents a clinically applicable and noninvasive model which calculates the spinal joint reaction forces at six different regions of the spine. Subjects completed four ambulatory activities of daily living: level walking, obstacle crossing, stair ascent, and stair descent. Results: Peak joint spinal reaction forces were compared between tasks and spine regions. Differences existed in the bodyweight normalized vertical joint reaction forces where the walking (8.05±3.19 N/kg) task had significantly smaller peak reaction forces than the stair descent (12.12±1.32 N/kg) agreeing with lower extremity data comparing walking and stair descent tasks. Conclusion: This method appears to be effective in estimating the joint reaction forces using a segmental spine model. The results suggesting the main effect of peak reactions forces in the segmental spine can be influenced by task.
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The present paper investigates the forces and the stresses in the lumbrical and the other finger motors in an unloaded human finger model, with and without the ab-adduction degree of freedom of the MCP joint. Unique solutions are ...
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The present paper investigates the forces and the stresses in the lumbrical and the other finger motors in an unloaded human finger model, with and without the ab-adduction degree of freedom of the MCP joint. Unique solutions are obtained by minimization of the maximal muscle stress calculated with a normal and a variable lumbrical physiological cross-sectional area. It is concluded that in the model with biaxial MCP joint, a stronger than normal lumbrical is not useful in unloaded finger control, and will merely result in spare lumbrical capacity. Also the natural synergism of the lumbrical and the ulnar interosseus in the control of the finger in the sagittal plane is pointed out. (C) 1997 Elsevier Science Ltd. All rights reserved. [References: 13]
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The external osteosynthesis is one of the methods of healing bone fractures. The idea of external fixators design consists in inserting into the bone fragments elements, which are coupled outside the limb by an element, called the...
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The external osteosynthesis is one of the methods of healing bone fractures. The idea of external fixators design consists in inserting into the bone fragments elements, which are coupled outside the limb by an element, called the frame of the fixator, having the fracture set. The external fixation is based on the principle of " load transfer". The design of a new generation of external fixators ought to employ some methods of mechanical analysis. Selected problems related to the modelling and simulation of physical performance of the unilateral external mechatronic orthopaedic fixator-bone system are presented. The majority of works makes use of the rigid finite element method for analysing the orthopaedic device-bone system. The paper presents some problems regarding mechanics applied in the external osteosynthesis design.
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The achilles tendon is one of the strongest tendons in the human body, and a healthy tendon will only rupture under very severe conditions. Experiments and statistics show a high probability of tendon rupture in the case of a pers...
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The achilles tendon is one of the strongest tendons in the human body, and a healthy tendon will only rupture under very severe conditions. Experiments and statistics show a high probability of tendon rupture in the case of a person trying to make a quick start and thereby toppling over in the ankle joint. Toppling over means a quick overturning in the lower ankle joint as it may occur when starting out of the sagittal plane. Based on a verified model of the achilles tendon, of M. Gastrocnemius and M. Soleus (Hatze, H. (1980) IEEE Trans. Automatic Control 25, 375-385; Hoy et al. (1990) J. Biomechanics 23, 157-169; Komi (1984) Meh Sci. Sports Exerc. 16, 26-28; Pandy ct al. (1990) J. Biomechanics 23, 1185-1198.), the stress in different tendon fibres during such a movement is investigated. The results of this simulation show that the expected extreme stresses in the lateral tendon fibres are a possible starting point for a rupture. [References: 19]
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An important aspect of accurate representation of human movement is the ability to account for differences between individuals. The following paper proposes a methodology using Hill-based candidate functions in the fast orthogonal...
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An important aspect of accurate representation of human movement is the ability to account for differences between individuals. The following paper proposes a methodology using Hill-based candidate functions in the fast orthogonal search (FOS) method to predict translational force at the wrist from flexion and extension torque at the elbow. Within this force-prediction framework, it is possible to implicitly estimate subject-specific physiological parameters of Hill-based models of upper arm muscles. Surface electromyography data from three muscles of the upper arm (biceps brachii, brachioradialis, and triceps brachii) were recorded from ten subjects, as they performed isometric contractions at varying elbow joint angles. Estimated muscle activation level and joint angle were utilized as inputs to the FOS model. Subject-specific estimates of optimal joint angles for the three muscles were determined via frequency analysis of the selected FOS candidate functions.
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