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1

Discussion on angular asymmetry in the solutions of SLIP model

Kowalczyk Piotr, Płociniczak Łukasz, Wróblewska Zofia

Mathematica Applicanda

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2023

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Vol. 51, no. 2

223--237

EN

We consider a spring-mass model of human running which is built upon an inverted elastic pendulum. The model itself consists of two sets of differential equations - one set describes the motion of the centre of mass of a runner in contact with the ground (support phase), and the second set describes the phase of no contact with the ground (flight phase). In our previous approach, we assumed that periodic solutions in the support phase are symmetrical with respect to the touch-down and take-off angles for the large spring constant (or small angle of attack). Based on proposed solutions, we introduce analytical approximations of an asymmetrical boundary value problem, which brings our model closer to real running. By appropriately concatenating asymptotic solutions for the two gait phases, we are able to reduce the dynamics to a one-dimensional apex to apex return map and then to investigate the existence and stability of periodic solutions. Unlike in the symmetrical version, we could not find sufficient conditions for this map to have a unique stable fixed point. Extending the model with the possibility of taking off with the angle other than during landing, the aforementioned asymmetry, is necessary in the context of real run considerations. Thanks to this, our work could be enriched by experimental results. In this paper, we will present the possible reasons for the instability of asymmetric solutions in conjunction with conclusions from the observation of real runs.

PL

W pracy rozważamy model biegu, w którym człowiek sprowadzony jest do punktu masy na nieważkiej sprężynie, a momencie kontaktu z podłożem staje się odwróconym sprężystym wahadłem. Sam model składa się z dwóch zestawów równań różniczkowych - jedno opisuje ruch środka masy biegacza podczas kontaktu stopy z podłożem (faza podparcia), a drugi fazę lotu. W naszym poprzednim podejściu zakładaliśmy, że rozwiązania okresowe w fazie podparcia są symetryczne względem kątów lądowania i odbicia dla dużej wartości sztywności nogi (lub małego kąta ataku). Na podstawie proponowanych rozwiązań wprowadzamy analityczne przybliżenia asymetrycznego problemu brzegowego, co zbliża nasz model do rzeczywistego biegu. Odpowiednio łącząc asymptotyczne rozwiązania dla obu faz biegu, jesteśmy w stanie zredukować dynamikę do jednego wymiaru i utworzyć odwzorowanie powrotu od wierzchołka do kolejnego wierzchołka praboli lotu, a następnie badać istnienie i stabilność rozwiązań okresowych. W odróżnieniu od wersji symetrycznej, nie mogliśmy znaleźć wystarczających warunków, aby to odwzorowanie miało jednoznacznie określony stabilny punkt stały. Rozszerzenie modelu o możliwość odbicia pod innym kątem, niż podczas lądowania (asymetria), jest konieczne w kontekście rozważań nad rzeczywistym biegiem. Dzięki temu nasza praca mogła zostać wzbogacona o wyniki eksperymentalne. W tym artykule przedstawimy możliwe przyczyny niestabilności asymetrycznych rozwiązań w połączeniu z wnioskami z obserwacji rzeczywistych biegów.

2

Comparative analysis of dynamic load models generated by runners on footbridges

Pańtak Marek

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

147--162

EN

Footbridges, like all building structures, must be designed in a way that ensures their safe and comfortable use. Steel footbridges characterised by low vibration damping often turn out to be a structure susceptible to the dynamic influence of users during various forms of their activity. For these structures, the impact of running users may be a key type of dynamic load for the verification of the serviceability limit state due to vibrations. In the literature, there are several proposals for models of dynamic load generated by runners (models of ground reaction forces - GRF). The paper presents the characteristics, analyses and comparisons of selected GRF load models. The analyses were performed using the GRF recorded during the laboratory tests of runners (tests planned and carried out by the author) and the GRF determined using various load models. In order to illustrate the accuracy of the estimation of the dynamic response of the structure, depending on the GRF model used, dynamic field tests and dynamic numerical analyses of the selected steel footbridge were carried out. The obtained results were analysed and compared.

PL

W artykule przedstawiono charakterystyki i analizy porównawcze wybranych modeli GRF. Analizy przeprowadzono z wykorzystaniem GRF zarejestrowanych podczas badań laboratoryjnych osób biegnących (badania własne autora) oraz GRF wyznaczonych z wykorzystaniem różnych modeli. W celu zobrazowania dokładności oszacowania odpowiedzi dynamicznej konstrukcji, w zależności od zastosowanego modelu GRF, przeprowadzono dynamiczne badania terenowe oraz dynamiczne analizy numeryczne stalowej kładki dla pieszych podatnej na oddziaływanie osób biegnących. Przeprowadzone analizy pozwoliły ustalić poprawność odwzorowania przebiegów GRF oraz dokładność wyznaczania odpowiedzi dynamicznej konstrukcji narażonych na dynamiczne oddziaływanie osób biegnących. W artykule przedstawiono własne zalecenia dotyczące modelowania oddziaływania osób biegnących na kładki dla pieszych oraz własne zalecenia dotyczące doboru parametrów wybranych modeli GRF opracowane na podstawie własnych badań sił reakcji podłoża generowanych podczas biegu. Zalecenia te pozwalają zwiększyć dokładność odwzorowania przebiegów GRF oraz dokładność oszacowania odpowiedzi dynamicznej konstrukcji narażonych na dynamiczne oddziaływanie osób biegnących. W szczególności: zaproponowano rozróżnianie technik biegu w celu dokładniejszego odwzorowania oddziaływań dynamicznych osób biegnących na konstrukcje, przedstawiono wartości współczynników Fouriera i przesunięć fazowych dla różnych technik biegu na potrzeby modelu bazującego na szeregu Fouriera, przedstawiono zalecenia dotyczące doboru wartości czasu kontaktu stopy z podłożem tcr dla różnych technik biegu na potrzeby modelu półsinusoidalnego (ang.: half-sine model), przedstawiono zalecenia dotyczące maksymalnych amplitud GRF dla różnych technik biegu oraz scharakteryzowano własną propozycję odwzorowania przebiegów GRF za pomocą funkcji Gaussa.

3

Redistribution of knee and ankle joint work with different midsole thicknesses in non-rearfoot strikers during running: a cross-sectional study

Miyazaki Tomohiro, Aimi Takayuki, Nakamura Yasuo

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 1

79--90

EN

The aim of this work was to i nvestigate the effects of midsole thickness on non-rearfoot strike runners’ redistributions of knee and ankle joint negative and positive work. Methods: Fourteen healthy male runners wore minimalist, traditional and maximalist shoes and ran in a straight line in each shoe in the laboratory at a speed of 15 km/h, with a ±5% difference being allowed. Whole-body kinematics and ground reaction forces were recorded, and the data of eleven non-rearfoot strikers were used for the analysis. Ankle and knee joint negative and positive work was calculated by integrating each joint’s torque power. Friedman test was used for statistical comparisons. Results: Running in minimalist shoes induced significantly greater ankle joint negative and positive work than in other shoes. Running in maximalist shoes induced significantly lower ankle joint positive work and greater knee joint negative work than in other shoes, and significantly greater knee joint positive work than in minimalist shoes. Conclusions: Our results indicated that nonrearfoot strikers redistributed joint negative and positive work from the knee to the ankle when using minimalist shoes or from the ankle to the knee when using maximalist shoes. It is recommended that future research employs more rigorous study designs, such as randomised controlled trials and longitudinal studies, to provide a more accurate assessment of the effect of these shoes on injury rates.

4

Effect of change in patellofemoral joint contact area by the decrease in vastus medialis muscle activation on joint stress

Tomoya Takabayashi, Mutsuaki Edama, Masayoshi Kubo, Takuma Inai

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 2

41--47

EN

Patellofemoral pain syndrome is a common orthopedic trauma among runners. It is unclear whether patellofemoral joint stress (PFJS) is the highest (or lowest) when the knee joint flexion angle and extension moment are in combination under the condition that vastus medialis (VM) activation decreases. This study aimed to investigate the effects of changes in the PFJ contact area by decreasing the activation of the VM muscle on PFJS. Methods: A PFJ sagittal model was used to quantify PFJ reaction force and PFJS. The PFJ model and mathematical modelling procedure were used to quantify PFJS based on previous studies. The simulation ranges were set to knee joint flexion angles of 10–45° and extension moments of 0–240 Nm. PFJS was calculated for the normal condition (NC) and decrease condition (DC) in VM activation. Results: When the knee joint angle and knee joint moment were at the maximum, the PFJS showed the maximum value under both conditions (NC; 14.9 N/cm2 , DC; 16.4 N/cm2 ). PFJS was found to be higher in DC than that in NC for all simulation ranges. Conclusion: Decreased VM activation may be involved in the mechanism of patellofemoral pain syndrome. In addition, the results of this study provide evidence that clinicians can enhance VM to relieve pain in patients with patellofemoral pain syndrome.

5

Reliability of the RunScribe™ system to determine kinematic variables of the pelvis during locomotion at different speeds

Marcos-Blanco Aitor, García-Pinillos Felipe, Molina-Molina Alejandro, Jaén-Carrillo Diego, Soto-Hermoso Víctor, Ruiz-Alias Santiago

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 3

83--90

EN

The aim of this study was to determine the reliability of the RunScribe™ system to measure kinematic variables of the pelvis during walking and running. Methods: In this study, a treadmill protocol was implemented where the participants (n = 23) completed 3 sets of 1 minute at 5, 10 and 15 km/h. Results: All the recorded measurements during walking reported a low reliability with coefficients of variation (CV) greater than 10% in all variables and small-moderate intraclass correlation coefficient (ICC) (<0.6) in seven out of ten variables. Similarly, the CVs reported in running were greater than 10%, except for the maximum angular rate in the obliquity of the pelvis and the vertical oscillation that together with the angular velocity variables showed almost perfect ICCs (>0.92). Conclusions: Therefore, the data obtained suggests that the RunScribe™ system with 3 IMUs does not provide reliable metrics about the kinematics of the pelvis during locomotion (i.e., walking and running).

6

Effect of foot pronation during distance running on the lower limb impact acceleration and dynamic stability

Xiang Liangliang, Gu Yaodong, Wang Alan, Mei Qichang, Yu Peimin, Shim Vickie, Fernandez Justin

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 4

21--30

EN

Foot pronation is not an isolated factor influencing lower limb functions. Exploring gait variability and impact loading associated with the foot posture are crucial for understanding foot pronation-related injury mechanisms. This study aimed to evaluate how foot posture affects impact loading and running variability during running. Methods: Twenty-five male participants were recruited into this study. Pressure under the foot arch, acceleration and marker trajectory were recorded in the right limb for each runner after 1, 4, 7 and 10 km running, respectively. Linear mixed effects models were used to analyze the statistical difference of the data. Results: FPI-6 has significantly increased after the 10 km running ( p < 0.01). For the tibial acceleration, peak resultant acceleration after 10 km running was significantly increased than after 4 km running ( p = 0.02). At the dorsum of the foot, the short-time largest Lyapunov exponent (LyE) after 10 km running decreased 0.28 bit/s compared with LyE after 7 km running ( p = 0.03). In the tibia, LyE after 4 km and 10 km running was decreased significantly ( p < 0.01 and p = 0.01). Conclusions: The foot was significantly pronated at the middle and at the end of running. Foot pronation during distance running increased the distal tibia peak impact acceleration but did not increase running instability.

7

Lower extremity stiffness in habitual forefoot strikers during running on different overground surfaces

Zeng Ziwei, Yin Lulu, Zhou Wenxiong, Zhang Yy, Jiang Jiayi, Wang Lin

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 2

73--80

EN

Purpose: Sports surface is one of the known external factors affecting running performance and injury. To date, we have found no study that examined the lower extremity stiffness in habitual forefoot strikers running on different overground surfaces. Therefore, the objective of this study was to investigate lower extremity stiffness and relevant kinematic adjustments in habitual forefoot strikers while running on different surfaces. Methods: Thirty-one male habitual forefoot strikers were recruited in this study. Runners were instructed to run at a speed of 3.3 m/s (±5%) on three surfaces, named synthetic rubber, concrete, and artificial grass. Results: No significant differences were found in leg stiffness, vertical stiffness, and joint stiffness in the sagittal plane during running on the three surfaces ( p > 0.05). Running on artificial grass exerted a greater displacement in knee joint angle than running on synthetic rubber ( p = 0.002, 95% CI = 1.52–7.35 degrees) and concrete ( p = 0.006, 95% CI = 1.04–7.25 degrees). In the sagittal plane, peak knee moment was lower on concrete than on artificial grass ( p = 0.003, 95% CI = 0.11–0.58 Nm/kg), whereas peak ankle moment was lower on synthetic rubber than on concrete (p < 0.001, 95% CI = 0.03–0.07 Nm/kg) and on artificial grass (p < 0.001, 95% CI = 0.02–0.06 Nm/kg). Among the three surfaces, the maximal ground reaction forces on concrete were the lowest (p < 0.05). Conclusions: This study indicated that running surfaces cannot influence lower extremity stiffness in habitual forefoot strikers at current running speed. Kinematic adjustments of knee and ankle, as well as ground reaction forces, may contribute to maintaining similar lower extremity stiffness.

8

The meaning of physical activity in the quality of life management aspect

Rosak-Szyrocka Joanna, Clark Cain C. T., Abbas Ali Abdulhassan, Ullah Irfan

Quality Production Improvement - QPI

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2020

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Vol. 2, Iss. 1

69--76

EN

Quality of life is an ambiguous concept with a medical, sociological and economic dimension, as well as psychological, the most subjective one. Physical activity is considered one of the most important elements of a healthy lifestyle and a factor that determines the physical and mental health of an individual. The article presents the issue of physical activity in the aspect of quality of life management. It was found that respondents notice a very large relationship between sport and quality of life. The authors showed that it is very important in the quality of life management aspect not only to promote physical culture, but also to develop the habit of practicing it.

9

Approximate solutions and numerical analysis of a spring-mass running model

Wróblewska Zofia

Mathematica Applicanda

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2020

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Vol. 48, no. 1

25--48

EN

The paper refers to the classic spring-mass model of running, which was created on the basis of an inverted elastic pendulum. A new approximate solution of the boundary value problem relayed to the governing system based on two nonlinear ordinary differential equations is introduced, which we get in this model in a natural way. We give theoretical support by deriving asymptotic behaviour of obtained approximations. Simulations show that new solutions turn out very well. Our results are illustrated with some practical examples.

PL

W pracy rozważamy klasyczny model masy sprężynowej dla biegania oparty na odwróconym elastycznym wahadle. Przedstawiamy nowe przybliżone rozwiązanie interesującego zagadnienia brzegowego dla układu dwóch nieliniowych równań różniczkowych, które w naturalny sposób uzyskujemy w tym modelu. Badamy asymptotyczne zachowanie uzyskanych aproksymacji i podajemy asymptotyczną postać współczynnika spężystości nogi dla małych kątów ataku. Symulacje pokazują, że nowe rozwiązanie wypadło bardzo dobrze i wykazało dużą zgodność przybliżenia z rozwiązaniem dokładnym. Nasze wyniki zostały zilustrowane kilkoma praktycznymi przykładami pokazując, że pomiary parametrów biegu lekkoatletów są bliskie wartościom uzyskanym z modelu.

10

Quality of life improvement in Kaizen aspect

Rosak-Szyrocka Joanna

Quality Production Improvement - QPI

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2019

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Vol. 1, Iss. 1

528--536

EN

The aim of the research is to analyze the quality of life improvement (Kaizen) in the running aspect in Poland. Until now, issues related to the running analysis of the quality life in terms were not the subject of broader, comprehensive scientific considerations. The research was taken in 2019 year and covered a group of 396 runners. The respondents are women posing 67,9% and men posing 32,1% residing in different areas of Poland. The research was based on a questionnaire (CAWI - Computer Assisted Web Interview). Although for most respondents the result is not the most important, they try to improve their running attitude and time. Runners use different ways to be motivated to work on themselves. An example of motivators can be a medal, obtained at the finish line or sharing success with participation in competition on social networks (Facebook).

11

Acute effects of different orthoses on lower extremity kinetics and kinematics during running; a musculoskeletal simulation analysis

Sinclair Jonathan, Ingram Jane, Taylor Paul John, Chockalingam Nachiappan

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 4

13--25

EN

The current investigation aimed to examine the effects of different orthotic conditions on the biomechanical mechanisms linked to the aetiology of chronic pathologies using musculoskeletal simulation. Methods: 16 male and 20 females ran over an embedded force plate at 4.0 m/s, in five different conditions (medial, lateral, no-orthoses, semi-custom and off the shelf). Kinematics of the lower extremities were collected using an eight-camera motion capture system and lower extremity joint loading also explored using a musculoskeletal simulation approach. Differences between orthoses conditions were examined using 2  2 mixed ANOVA. Results: External instantaneous load rate was significantly reduced in the off the shelf orthoses (male = 1290.60 and female = 1567.10 N/kg/s), compared to the medial (male = 1480.45 and female = 1767.05 N/kg/s) and semi-custom (male = 1552.99 and female = 1704.37 N/kg/s) conditions. In addition, peak patellofemoral stress was significantly lower in the off the shelf orthoses (male = 68.55 and female = 94.91 KPa/kg) compared to the lateral condition (male = 70.49 and female = 103.22 KPa/kg). Finally, peak eversion angles were significantly attenuated in the medial orthoses (male = –6.61 and female = –7.72 deg) compared to the lateral (male = –9.61 and female = –10.32 deg), no-orthoses (male = –8.22 and female = –10.10 deg), semi-custom (male = –8.25 and female = –9.49 deg) and off the shelf (male = –7.54 and female = –8.85 deg) conditions. Conclusions: The current investigation shows that different orthotic devices/ configurations may provide distinct benefits in terms of their effectiveness in attenuating the biomechanical parameters linked to the aetiology of chronic running injuries.

12

The influence of minimalist and conventional sports shoes and lower limbs dominance on running gait

Jandova S., Volf P., Vaverka F.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 3

3--9

EN

Purpose: The aim of this study was to determine how minimalist running shoes (MRS), conventional running shoes (CRS) and the dominance of lower limbs influence the running gait. Methods: Trained recreational runners (N = 13) who have been engaged in regulary running for more than one year were participants in this study. They were experienced with using MRS and CRS for more than half year and they used both types of shoes. An in-shoe pressure measuring system (Pedar-X®, Novel, Munich, Germany) was used to monitor plantar pressure and vertical force and the temporal parameters when running in MRS and CRS during the stance phase, the swing phase and over one stride. Results: Running in CRS significantly prolonged stance, swing and stride phases by 2–11% compared to MRS. In contrast, when running in MRS significantly larger values of maximum pressure (9–14%) and maximum vertical force (3–7%) than in CRS were found. Conclusions: For this reason, running in MRS could be recommended to recreational runners only with care. The effect of limb dominance on temporal characteristics was detected when running in CRS. Significantly longer stance phase for dominant limb is associated with a shorter swing. The kinematics variables were significantly higher for dominant limb than for non-dominat limb when running in MRS and CRS (by 12–23%).

13

Relationship between lower limbs kinematic variables and effectiveness of sprint during maximum velocity phase

Struzik A., Konieczny G., Grzesik K., Stawarz M., Winiarski S., Rokita A.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 4

131--138

EN

Purpose: The aim of the study was to determine the relationships between time of running over a 15–25 m section of a 30-meter run along a straight line and changes in the angle and angular velocity observed in ankle, knee and hip joints. Therefore, the authors attempted to answer the question of whether a technique of lower limbs movement during the phase of sprint maximum velocity significantly correlates with the time of running over this section. Methods: A group of 14 young people from the Lower Silesia Voivodeship Team participated in the experiment. A Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using Noraxon MyoMotion system. Results: There were observed statistically significant relationships between sprint time over a section from 15 to 25 m and left hip rotation (positive) and between this time and left and right ankle joint dorsi-plantar flexion (negative). Conclusions: During the maximum velocity phase of a 30 m sprint, the effect of dorsi-plantar flexion performed in the whole range of motion was found to be beneficial. This can be attributed to the use of elastic energy released in the stride cycle. Further, hip rotation should be minimized, which makes the stride aligned more along a line of running (a straight line) instead of from side to side.

14

Kinematic and kinetic analyses of novice running in dress shoes and running shoes

Lee Y., Kim Y. K., Kim Y. H., Kong S., Lee K. K.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 3

55-61

EN

The purpose of the study was to investigate how novice runners adjust their lower extremities in heel-toe running while they wear dress shoes and running shoes. Ten novice male runners repeatedly ran across a force plate at 4 m/s in each type of shoes. Joint kinematics and kinetics, vertical ground reaction force, and utilized coefficient of friction during the stance phase were quantified. The results obtained showed no differences in impact peaks, stance time, stride length and joint kinematics. However, dorsiflexion moment was significantly greater with dress shoes (407 Nm) compared to that with running shoes (304 Nm; p < 0.05). Compared to the runners in running shoes (0.23), the runners in dress shoes (0.20) achieved a significantly lower utilized coefficient of friction ( p < 0.05). When running in dress shoes, novice runners tended to use better a dorsiflexion moment than when running in running shoes. This adaptation appears to minimize the chances of slipping at the moment of heel strike.

15

Analyze of vertical acceleration of the body mass center during running on treadmill

Staniak Z., Buśko K., Karpiłowski B., Nosarzewski Z., Witek K.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2006

|

z. 26

339-344

EN

The work presents analyze of vertical acceleration curve of the body mass center (VACM characteristic) obtained by eleven athletes during on treadmill running with gradual rise velocity. The measurements are made by uniaxial accelerometer placed in loins part of trunk near the center of body mass. The chosen value of characteristics was calculated for every single run with applied velocity of treadmill The velocity of treadmill of every run was significantly correlated to mean values of VACM characteristics calculated for all subjects. For every athletes analyzed mean values of characteristics calculated separately for left and right steps were significantly different.

16

Analiza zachowań hamulców elektromagnetycznych ciernych w warunkach nieustalonych

Igielski J.

Przegląd Elektrotechniczny

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2006

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R. 82, nr 10

29-33

PL

W artykule przedstawiono zachowania elektromagnetycznych hamulców ciernych proszkowych i płytkowych przeznaczonych do zadawania obciążenia w badaniach układów napędowych małej mocy. Wykazano, że na przebieg rozwijanego przez takie hamulce momentu będą miały wpływ zmiany wartości obrotowej oraz charakter narastania prądu wzbudzenia. Szybszą reakcją na pobudzenie charakteryzowały się hamulce płytkowe.

EN

The article presents the behavior of plate and powder electromagnetic friction brakes that are meant to introduce load in the research on low-power mechatronic devices. It has been showed that the course of torque developed in these kinds of brakes will influence the rotational speed value. It will be also significant in the increase of the field current. The plate brakes have reacted much faster on the stimulation reaction than the powder brakes.