Wyniki wyszukiwania - Biblioteka Nauki

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Analysis of center of pressure displacements and head movements triggered by a visual stimulus created using the virtual reality technology

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Wodarski P. , Jurkojć J. , Chmura M. , Gruszka G. , Gzik M.

Acta of Bioengineering and Biomechanics

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2022

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tom Vol. 24, no. 1

20--28

EN

The purpose of the study was to determine how a stimulus presented in the virtual reality environment as a simulation of a fall off the stairs, triggers a loss of balance. The study also examined if the head movement measurements and the analysis in the frequency domain could increase the range of interpretation. Methods: 11 healthy individuals were tested, two [A1] were identified as more susceptible to the introduced disturbance, and one reported having dizziness, car sickness and fear of heights. Measurements of center of pressure (COP) and head positions were performed in the real and in the virtual environment. The beginning of the simulation was either unexpected or preceded by a signal. The analysis included standard parameters determined in time domain as well as the amplitude of the first harmonic from the fast Fourier transform (FFT). Results: The analysis did not reveal statistically significant differences between results obtained: in real and virtual environments, with and without the warning signal. It was possible to notice the effect of virtual disturbance in the three selected individuals; this was particularly evident in the analysis of the first harmonic of the FFT. Conclusions: The conducted tests revealed that the limitation of the analyses exclusively to the time domain could be insufficient for a comprehensive interpretation. The effect of introduced disturbance was particularly noticeable in the analysis of the first harmonic for head movement. The application of this parameter could enable a more accurate investigation of a strategy aimed at maintaining balance.

2

Effectiveness of the power and speed dry-land training in female swimmers aged 15–16

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Guzik-Kopyto A. , Nowakowska-Lipiec K. , Nocoń A. , Gzik M. , Michnik R.

Acta of Bioengineering and Biomechanics

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2021

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tom Vol. 23, no. 2

13--21

EN

Purpose: This work aimed to define the impact of the introduction of power and speed dry-land training in female swimmers aged 15–16 on the rise of time results at a distance of 200 m and on the increase of the strength level of the muscle groups in the elbow joint. Method: The investigations were conducted on a group of 28 junior female swimmers: group 1 (aged 13–14) with speed and endurance training based on “water” exercises; group 2 (aged 15–16) with extra power and speed dry-land training. The following parameters were analyzed: time results, the moments of muscle forces in the elbow joint at the extension and flexion movements in isokinetic conditions and the ratio of the values of moments of muscle forces of flexors in relation to extensors. Results: Statistically significant differences between groups were found for the following parameters: the time results from swimming 200 m with ( p < 0.001) and without using lower limbs ( p = 0.031), the ratio of the moments of muscle forces of flexors to extensors ( p < 0.05). Conclusions: The results of the correlation analysis show that the higher the moments of muscle forces of flexors and extensors of the elbow joint, the shorter the time obtained in swimming 200 m in the freestyle stroke.

3

Assessment of gait stability and preferred walking speed in virtual reality

86%

Wodarski P. , Jurkojć J. , Polechoński J. , Bieniek A. , Chrzan M. , Michnik R. , Gzik M.

Acta of Bioengineering and Biomechanics

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2020

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tom Vol. 22, no. 1

127--134

EN

Analysis of human gait as well as diagnosis of human locomotion organ should always be conducted with velocity of gait equal to Preferred Walking Speed (PWS). The literature review shows that the PWS value is not the same in real and virtual environment. The aim of this study was to determine PWS values in both environments and to specify values of parameters used in equations enabling PWS calculations on the basis of lower limb length. Methods: Research-related tests involved 40 subjects walking on the treadmill and wearing HMD goggles. The spatial scenery made participants feel like during a walk in the park. The tests included measurements of displacements of the COP, allowing for the calculation of the Lyapunov exponent and Floquet Multiplier. Both coefficients were used to identify stability at various gait velocities. Results: The analysis revealed that the PWS in relation to gait on the treadmill with VR was lower than the PWS without VR. The final stage of research involved the determination of new values of coefficients of the formula enabling the identification of the velocity of comfort of gait in VR. Conclusions: Obtained results proved that PWS in real and virtual environment are different. The lower values were obtained for measurements in VR. On the basis of these results, value of the “a” coefficient, used in PWS calculations on the basis of lower limb length, was re-determined. The new value makes it possible to assess PWS for gait conducted on treadmill in virtual environment, what can be very important in gait evaluation.

4

Gait Kinematics Index, Global Symmetry Index and Gait Deviations Profile: Concept of a new comprehensive method of gait pathology evaluation

86%

Jochymczyk-Woźniak K. , Nowakowska-Lipiec K. , Zadoń H. , Wolny S. , Gzik M. , Gorwa J. , Michnik R.

Acta of Bioengineering and Biomechanics

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2020

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tom Vol. 22, no. 4

61--73

EN

The objective of the work was to define a new comprehensive method of evaluating gait pathology (Gait Kinematics Index, Global Symmetry Index and Gait Deviations Profile). Methods: The article presents in detail a mathematical algorithm of a new comprehensive method of evaluating gait pathology. Input data for the algorithm are the kinematic parameters of gait. The method is based on the determination of the following parameters: standardized angular variables (Wji), kinematic indicators of gait (KIj), gait cycle indicators (GCIi), Gait Kinematic Index (GKI), Gait Deviations Profile (GDP, GDPj), Global Symmetry Index (GSI) and Symmetry Indices (SIj) for kinematic gait values. The algorithm is based on the determination of the difference between results obtained in relation to the kinematics of movement of a given patient and the average value obtained in relation to the standard in each percentage of a gait cycle. The proposed method was tested using results obtained for 59 healthy persons and one patient with locomotor function disorder. Results: The GKI values for the reference group amounted to 0.89 ± 0.23. Information which can be obtained using the proposed gait assessment method was presented using an example of a patient with the disorder of locomotor functions. Areas of gait deviations, which were identified on the basis of the determined indicators, were presented in a graphic form using GDP. Conclusions: The new gait assessment method makes it possible to identify gait using a single numerical value, evaluate movements in individual joints and in subsequent moments as well as to assess the symmetry of gait.

5

The influence of isometric rotation of the lower limb on the functioning of the knee joint stabilizers and rotator muscles

86%

Chrzan M. , Michnik R. , Myśliwiec A. , Wodarski P. , Suchoń S. , Gzik M. , Mitas A.

Acta of Bioengineering and Biomechanics

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2022

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tom Vol. 24, no. 4

139--146

EN

This paper presents an assessment of the influence of isometric rotation of the lower limb in a standing position on the functioning of the muscles stabilizing the knee joint in the frontal plane with the use of modeling the loads on the musculoskeletal system. Methods: The research was carried out in the AnyBody Modeling System software, performing multi-variant simulations of the musculoskeletal system during isometric rotation of the lower limbs. The simulations were carried out using as input data the values of rotating moments and the ground reaction forces acting on foot segments, which were measured using the proprietary Rotenso device and the position of the body segments. Results: The result is the muscular activity of the lower limbs of the selected muscle groups during isometric rotation. Muscle activity was recorded for Sartorius, Tensor fasciae latae, Iliopsoas, Gluteus minimus, Gluteus medius, Gluteus maximus, Piriformis, Quadratus femoris, Obturator internus, Obturator externus, Gemellus inferior, Gemellus superior. Conclusions: Performing isometric rotation allowed for the activation of most of the knee joint stabilizing muscles and rotators of the lower limb. The results indicate that lower limb rotation exercises can be used in physiotherapy in patients with valgus knee.

6

Finite element head model for the crew injury assessment in a light armoured vehicle

86%

Burkacki M. , Wolański W. , Suchoń S. , Joszko K. , Gzik-Zroska B. , Sybilski K. , Gzik M.

Acta of Bioengineering and Biomechanics

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2020

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tom Vol. 22, no. 2

173--183

EN

Purpose: The aim of this paper was the development of a finite element model of the soldier’s head to assess injuries suffered by soldiers during blast under a light armoured vehicle. Methods: The application of a multibody wheeled armoured vehicle model, including the crew and their equipment, aenabled the researchers to analyse the most dangerous scenarios of the head injury. These scenarios have been selected for a detailed analysis using the finite element head model which allowed for the examination of dynamic effects on individual head structures. In this paper, the authors described stages of the development of the anatomical finite element head model. Results: The results of the simulations made it possible to assess parameters determining the head injury of the soldier during the IED explosion. The developed model allows the determination of the parameters of stress, strain and pressure acting on the structures of the human head. Conclusion: In future studies, the model will be used to carry out simulations which will improve the construction of the headgear in order to minimize the possibility of the head injury.

7

Evaluation of the strength properties of materials intended for tracheobronchial tubes

86%

Sobota R. , Markowski J. , Joszko K. , Gzik-Zroska B. , Kawlewska E. , Gzik M.

Engineering of Biomaterials

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2020

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tom Vol. 23, no. 156

10--16

EN

The desire to increase the comfort of patients and to continue production despite the decreasing amount of available materials on the market has led to the constant search for novel materials that could be used to obtain tracheobronchial tubes. The aim of this study is to determine the mechanical properties of a new thermoplastic elastomer. Two materials - the thermoplastic elastomer and the natural rubber were subjected to three tests: static tensile test, static compression test and static three-point bending test. During the static tensile test, samples of the tested materials were examined, and during the next two examinations, the final products. The materials underwent the processes of sterilization, hydrolytic degradation and degradation by oxidation. The treated samples were also tested in order to compare the obtained results. The mechanical properties of the tested materials improved both after the hydrolytic degradation and oxidative degradation, as well as after the sterilization process. Yet the thermoplastic elastomer revealed a more noticeable increase. The elastomer hardening is a positive phenomenon potentially leading to fewer accidental closures of the tubes cross-section. Both the sterilization process and various degradation methods improved the mechanical properties by strengthening the tested materials. This phenomenon seems to be desirable to avoid the closure of the implemented tube during its application.

8

Analiza biomechaniczna chodu weterana wojennego – analiza przypadku

86%

Nowakowska-Lipiec K. , Jochymczyk-Woźniak K. , Mikuła B. , Wolański W. , Gzik M. , Michnik R.

Aktualne Problemy Biomechaniki

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2019

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tom z. 18

29--37

PL

W pracy dokonano oceny biomechanicznej funkcji lokomocyjnych weterana wojennego. Uzyskane dla weterana wojennego wyniki ilościowej analizy chodu porównano z wartościami otrzymanymi dla grupy 56 zdrowych osób dorosłych, bez zaburzeń w obrębie narządu ruchu. Badania doświadczalne przeprowadzono z wykorzystaniem systemu optoelektronicznego BTS Smart. Analizie porównawczej poddano parametry czasowo-przestrzenne i kinematyczne chodu oraz zmiany energii całkowitej, potencjalnej, wypadkowej energii kinetycznej w czasie chodu. Uzyskane dla weterana wojennego wyniki znacznie odbiegały od wartości/zakresów normatywnych, wskazując na znaczne obrażenia aparatu ruch, które poniósł podczas wybuchu improwizowanego urządzenia wybuchowego.

EN

In the work the biomechanical evaluation of locomotion functions of a war veteran was made. The results of the quantitative gait analysis obtained for a war veteran were compared with the values obtained for a group of 56 healthy adults without locomotor disorders. Experimental studies were carried out using the BTS Smart optoelectronic system. The spatiotemporal and kinematic parameters of gait as well as changes in total energy, potential energy, kinetic energy and its components during gait were subjected to comparative analysis. The results obtained for a war veteran differed significantly from normative values / ranges, indicating significant injuries to the apparatus, which he suffered during the explosion of the improvised explosive device.

9

Experimental and modelling research on coach passengers’ safety in frontal impacts

72%

Jamroziak K. , Joszko K. , Wolanski W. , Gzik M. , Burkacki M. , Suchon S. , Szarek A. , Zielonka K.

Archives of Civil and Mechanical Engineering

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2020

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tom Vol. 20, no. 3

468--480

EN

Road traffic accidents involving coaches do not happen very often, but they are very dangerous because they affect a large number of passengers. Coaches (or intercity buses) are not equipped with safety belt harnesses. Valid regulations do not impose any obligation on coach manufacturers to provide intercity buses with either two- or three-point safety belts. This fact may result from the unawareness of risks and injuries that might befall the passengers with no safety belts during accidents. That is the reason why this work aims to compare the aftermath of coach accidents with no safety belts and the ones with safety belts. A detailed aim of this research is to analyse the results of dynamic loads during a frontal impact exerted on coach passengers travelling with and without (two- and three-point) safety belts. This objective was achieved by performing experimental studies and modelling which focused on the process of dynamic load transfer on the human body during a traffic accident. The research was conducted parallel on an adult and a child. The equivalent of a 50th percentile male was a hybrid III dummy (M50), whereas a child at the age of about 10 was represented by a P10 dummy. A numerical model was generated and verified in experimental testing in the scope of kinematics. Also, the comparison of the recorded courses of forces, acceleration, and moments was conducted. The results obtained from the tests were analyzed regarding the injury criteria for head, neck, and thorax. It was observed that both for the two-point safety system and the lack of safety belts, there were high values of acceleration recorded in the centre of gravity of the head. On the basis of the investigations conducted, it was ascertained that only a three-point safety belt system ensures the satisfaction of all injury criteria within admissible standards both in the case of criteria defined in the rules no. 80 and the rules no. 94 determined by the United Nations Economic Commission for Europe. It is the three-point safety belt system which should be obligatory in all intercity buses.