| 1. |
- Benosman, M. M., et al.
(författare)
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STRONG REAL-TIME QRS COMPLEX DETECTION
- 2017
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Ingår i: Journal of Mechanics in Medicine and Biology. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 0219-5194 .- 1793-6810. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- Heart rate variability (HRV) analysis is used as a marker of autonomic nervous system activity which may be related to mental and/or physical activity. HRV features can be extracted by detecting QRS complexes from an electrocardiogram (ECG) signal. The difficulties in QRS complex detection are due to the artifacts and noises that may appear in the ECG signal when subjects are performing their daily life activities such as exercise, posture changes, climbing stairs, walking, running, etc. This study describes a strong computation method for real-time QRS complex detection. The detection is improved by the prediction of the position of R waves by the estimation of the RR intervals lengths. The estimation is done by computing the intensity of the electromyogram noises that appear in the ECG signals and known here in this paper as ECG Trunk Muscles Signals Amplitude (ECG-TMSA). The heart rate (HR) and ECG-TMSA increases with the movement of the subject. We use this property to estimate the lengths of the RR intervals. The method was tested using famous databases, and also with signals acquired when an experiment with 17 subjects from our laboratory. The obtained results using ECG signals from the MIT-Noise Stress Test Database show a QRS complex detection error rate (ER) of 9.06%, a sensitivity of 95.18% and a positive prediction of 95.23%. This method was also tested against MIT-BIH Arrhythmia Database, the result are 99.68% of sensitivity and 99.89% of positive predictivity, with ER of 0.40%. When applied to the signals obtained from the 17 subjects, the algorithm gave an interesting result of 0.00025% as ER, 99.97% as sensitivity and 99.99% as positive predictivity.
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| 2. |
- Daggfeldt, Karl
(författare)
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Muscle Bulging Reduces Muscle Force and Limits the Maximal Effective Muscle Size
- 2006
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Ingår i: Journal of Mechanics in Medicine and Biology. - 0219-5194 .- 1793-6810. ; 6:3, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- A biomechanical model was generated in order to investigate the possible mechanisms behind reductions in muscle performance due to muscle bulging. It was shown that the proportion of fiber force contributing to the total muscle force is reduced with fiber bulging and that the cause of this reduction is due to the intramuscular pressure (IMP) created by the bulging fibers. Moreover, it was established that the amount of IMP generated muscle force reduction is determined by the extent to which muscle thickening restricts muscle fibers from shortening, thereby limiting their power contribution. It was shown that bulging can set a limit to the maximal size a muscle can take without losing force and power producing capability. Possible effects, due to bulging, on maximal muscle force in relation to both muscle length and muscle shortening velocity were also demonstrated by the model.
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| 3. |
- Wang, Bingyu, et al.
(författare)
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Prediction of Long Bone Fractures via Reconstruction of Pedestrian Accidents Using Multi-Body System and FE Models
- 2015
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Ingår i: Journal of Mechanics in Medicine and Biology. - : World Scientific Pub Co Pte Lt. - 0219-5194 .- 1793-6810. ; 15:1, s. Art. no. 1550016-
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed at prediction of long bone fractures and analysis of lower extremity injury mechanisms in real world passenger car to pedestrian collision. For this purpose, two cases of car to pedestrian accidents with detail recorded lower extremity injuries were reconstructed using Multi-body system (MBS) and Finite element (FE) models. The MBS models were used to determine lower extremity impact conditions, such as impact velocity, contact location as well as impact orientation. Furthermore, impact conditions were used to define initial boundary conditions in the simulation of lower extremity colliding with car front end using FE models. The bending moment and von Mises stress distributions of long bone were calculated in FE model to evaluate long bone fracture risks. Then, injury outcomes from simulations were compared with hospital recorded injury data. The simulation results of long bone fracture were consistent with the injury pattern and positions from hospital records. Moreover, the calculated fracture moments of tibia and fibula shaft as well as femur neck region were 310.8, 21.4 and 304.7Nm, respectively. The FE model is capable to reproduce the dynamic injury process and is an effective tool to demonstrate the dynamic response of the injury and to predict the risk of long bone fractures.
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| 4. |
- Wang, Fang, et al.
(författare)
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A NUMERICAL STUDY ON CORRELATION OF RIB FRACTURES WITH THORACIC INJURY CRITERIA IN OBLIQUE IMPACT
- 2017
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Ingår i: Journal of Mechanics in Medicine and Biology. - 0219-5194. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- Thoracic injury is one of the vital issues in vehicle side crashes. Experiments have been done widely to study thoracic injuries using biological subjects but less virtual tests were made by using Finite Element (FE) models. This study aimed at determining the correlation of the computationally calculated thoracic injury (Number of Rib Fractures NRF) with existing thoracic injury criteria under pure side and oblique impacts. For this purpose, a previously developed thorax FE model was validated by using Post Mortem Human Subject (PMHS) tests in pure side and oblique impacts in this study. The rib fractures were reconstructed and compared with the fractures observed in the PMHS tests. The model was then used to simulate rib fractures in human thorax impactor tests at Principal Direction of Force (PDOF) angles of 90 degrees to 35 degrees (total of 12 impacts). Furthermore, the normalized NRF were calculated and analyzed for comparing with normalized simulated injury parameters based on various human thoracic injury criteria, including contact force criterion, thorax deflection criterion, compression criterion, upper spine acceleration criterion and Thoracic Trauma Index (TTI). It is suggested that the TTI criterion has better correlation with the NRF than the other injury criteria.
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| 5. |
- Xiao, Sen, et al.
(författare)
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Development of a belted occupant fe model for prediction of chest injury risk based on stress and strain analysis
- 2017
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Ingår i: Journal of Mechanics in Medicine and Biology. - 0219-5194. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to investigate the chest injury in terms of chest deflections and rib fracture risks based on the stress/strain analysis via a belted occupant finite element model (BOM). The BOM was established using a human body model from the Global Human Body Models Consortium (GHBMC) and the model was validated against a frontal sled test with a Post-Mortem Human Subjects (PMHS). The bio-fidelity of the belted occupant model was then evaluated according to measured data from experimental test regarding detailed torso kinematics and seatbelt forces. The BOM was then used for prediction of the chest injury via calculated injury related parameters from simulations, including stress and strain distributions on the whole ribcage, which could not be fully measured in PMHS test. A study of chest injury risk was conducted with the validated model. Special concern is given to the injuries on rib fractures and chest deflections which have been correlated to the calculated stresses and strains. The results demonstrate that the validation can sufficiently meet the reconstruction of the test and the chest injury outcomes obtained from the simulation can fit the experiment, particularly the fracture risk of the rib 6 to the rib 11 on the chest along the seatbelt path. The current study provides a reference for virtual design and improvement of the chest injury investigation to better prevent chest injuries.
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| 6. |
- YUAN, M. I. N., et al.
(författare)
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A STUDY OF LIVER BIOMECHANICAL RESPONSES UNDER CLASSICAL IMPACTS FOR VEHICLE OCCUPANTS
- 2022
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Ingår i: Journal of Mechanics in Medicine and Biology. - 0219-5194. ; 22:7
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Tidskriftsartikel (refereegranskat)abstract
- Liver injury is one of the most fatal injuries in traffic accidents. To deeply study response characters of this injury under the unique impact condition, three impact tests are conducted based on the human body model and constraint systems of a car. This study is conducted based on the numerical method and adopts the orthogonal experimental design to deeply investigate the relationship between biomechanical responses and the impact loading variables. Data were collected and analyzed with the rotation of the liver in three planes and the distance change relative to the spine. Results show that in the near-side oblique impact, the maximum stress of the liver is captured as 10.041 MPa. In addition, the rotation angle of the liver in the three planes is the largest in the far-side oblique collision. In general, a more significant influence on the compression and movement of the liver is obtained from the near-side side collision, mainly because the door directly hits the left side of the occupant during crash process due to the limited space between door and occupant. In a far-side oblique collision, a buffering effect of the seat back to the driver does not play the role during the crash. As a result, the seatbelt slips off the occupant's shoulder, resulting in a high displacement of the upper body. Thus, ensuring the restraint effect of the seatbelt may be a crucial problem for far-side oblique collision. This study can provide a reference to the occupant safety protection during vehicle accidents.
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