Wyniki wyszukiwania - Biblioteka Nauki

1

Biomechanical Studies on Running the 400 M Hurdles

100%

Iskra J. , Coh M.

Human Movement

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2011

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tom 12

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nr 4

315-323

EN

Purpose. Biomechanical research conducted on hurdling are the basis for analysis of technique used in running disciplines. However, the 400 m hurdle run is an athletic discipline rarely subjected to individual biomechanical study. The aim of this study was to introduce the various forms of biomechanical studies on this difficult-to-quantify athletic event. Methods. In this study, 64 biomechanical articles were assessed, each covering various topics such as kinematics, dynamics, accelometrics and rhythm knowledge in the both the men's and women's 400 m hurdles. This was conducted with regard to the specificity of studies on the 400 m hurdles, including their types, methods and difficulties. The characteristics of the study were divided, among others, into: physiological effort, centrifugal force, dynamics of movement, stride rhythm, the level of abilities, laterality and type of body build. Results. Numerous sources allowed the creation of a general outline of present biomechanical studies. Conclusions. Within the context of the conducted analysis on the present state of biomechanical analysis on the 400 m hurdles, a number of basic principles were outlined that could determine the effectiveness of future research possibilities for scientists on the 400 m hurdles.

2

KinematiC PPP using mixed GPS/GLONASS single-frequency observations

100%

Hamed M. , Abdallah A. , Farah A.

Artificial Satellites : Journal of Planetary Geodesy

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2019

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tom Vol. 54, No. 3

97--112

EN

Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Singlefrequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-frequency, GPS/GLONASS GNSS receiver and singlefrequency data have been processed. Net_Diff software was used for processing all the data. The results have been compared with a reference solution. Adding GLONASS satellites significantly improved the satellite number and Position Dilution Of Precision (PDOP) value and accordingly improved the accuracy of positioning. In the case of “ADIS” data, the 3D Root Mean Square Error (RMSE) ranged between 0.273 and 0.816 m for GPS only and improved to a range from 0.256 to 0.550 m for GPS/GLONASS for the 6 processed days. An average improvement ratio of 24%, 29%, 30%, and 29% in the east, north, height, and 3D position components, respectively, was achieved. For the kinematic trajectory, the 3D position RMSE improved from 0.733 m for GPS only to 0.638 m for GPS/GLONASS. The improvement ratios were 7%, 5%, 28%, and 13% in the east, north, height, and 3D position components, respectively, for the kinematic trajectory data. This opens the way to add observations from the other two constellations (Galileo and BeiDou) for more accuracy in future research.

3

Effects of Unstable Conditions on Kinematics and Performance Variables in Young Handball Players

100%

Urbán T. , Gutiérrez Ó. , Moreno F. J.

Journal of Human Kinetics

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2015

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tom 46

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nr 1

39-48

EN

The execution variability and outcomes found in throwing actions have received special attention in numerous studies in recent years. The aim of this study was to analyze the effect of an unstable condition on velocity, accuracy and kinematics of movement in the seven metres throw in handball. Twenty-five young handball players took part in an experiment, throwing towards a target on a stable and an unstable surface. Each participant performed 32 throws, 16 for each situation. Linear variability of the dominant hand was assessed by 3D Motion Tracking. A radar sports gun was used to record the velocity of the ball and the throws were video recorded to establish their accuracy. Results showed significant decreases in throwing velocity in unstable conditions, but these did not significantly affect the accuracy achieved in performance. Differences were also found in movement kinematics between the two throwing conditions and relationships were found between kinematics, velocity and accuracy.

4

Digital Road Profile using kinematic GPS

100%

Farah A.

Artificial Satellites : Journal of Planetary Geodesy

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2009

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tom Vol. 44, No. 3

95--101

EN

A Digital Road Profile (DRP) is a digital representation of road surface topography or terrain in the longitudinal direction. The need for accurate DRP is vital in two stages; before the road construction starts and after the road construction finished where the verification of its geometrical characteristics is essential for engineering safety purposes. Classical surveying techniques are traditionally used for the DRP generation with limitation of high-cost and time-waste. Kinematic DGPS or Real Time Kinematic DGPS positioning can provide accurate enough results for such application. This paper presents an assessment study of using kinematic GPS technique for DRP generation comparing with classical survey in south Egypt. The results shows that, vehicle-GPS system used in combination with post processing kinematic DGPS gave satisfactory accuracy for nearly all points for a distance of nearly 2 km. with max. and min. difference not more than 7.7 cm, a mean value of 0.10 cm and a Root Mean Square RMS value of 4.11 cm.

5

Accuracy assessment of Digital Elevation Models using GPS

100%

Farah A. , Talaat A. , Farrag F. A.

Artificial Satellites : Journal of Planetary Geodesy

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2008

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tom Vol. 43, No. 4

151--161

EN

A Digital Elevation Model (DEM) is a digital representation of ground surface topography or terrain with different accuracies for different application fields. DEM have been applied to a wide range of civil engineering and military planning tasks. DEM is obtained using a number of techniques such as photogrammetry, digitizing, laser scanning, radar interferometry, classical survey and GPS techniques. This paper presents an assessment study of DEM using GPS (Stop&Go) and kinematic techniques comparing with classical survey. The results show that a DEM generated from (Stop&Go) GPS technique has the highest accuracy with a RMS error of 9.70 cm. The RMS error of DEM derived by kinematic GPS is 12.00 cm.

6

Effects of Fatigue Induced by Prolonged Gait When Walking on the Elderly

88%

Pereira M. , Gonçalves M.

Human Movement

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2011

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tom 12

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nr 3

242-247

EN

Purpose. Fatigue has been pointed as a fall risk in the elderly; however, the effects of prolonged gait on neuromuscular recruitment and on its pattern remain unknown. The aim of this study was to evaluate the effects of prolonged gait on neuromuscular recruitment levels and spatial-temporal gait variables. Methods. Eight healthy older women (age: 72.63 ± 6.55 years) walked at their preferred walking speed for twenty minutes on a treadmill. The Root Mean Square (RMS) from the vastus-lateralis, femoral biceps, tibialis anterior and lateral gastrocnemius muscles were determined at the first and last minute of the test during the moments of Heel Strike (HS), Terminal Stance and Terminal Swing (TS). In addition, coactivation in the knee and ankle as well as the stride cadence and length were measured in the test. The two RMS data (taken at the first and last minute) were compared by means of a Student's t-test. Results. Twenty minutes of walking induced fatigue in the subjects, as observed through an increase in RMS, notably during the HS and TS. Coactivation was also influenced by the prolonged gait test. The only gait phase where a risk of falling was enhanced was the HS. Nonetheless, subjects developed strategies to maintain a safe motor pattern, which was evidenced by an increase in stride length and a decrease in stride cadence. Conclusion. Tests lasting just twenty minutes on a treadmill were enough to induce fatigue in older adults. However, the level of fatigue was not enough to present a danger or fall risk to elderly individuals.

7

Kinematic evaluation of contrary body movement in sport ballroom dancing

88%

Kuliś S. , Gajewski J.

Acta of Bioengineering and Biomechanics

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2022

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tom Vol. 24, no. 2

120--128

EN

The aim of the study was to analyse the contrary body movement in Viennese waltz performed by dancesport athletes and to determine its relationship on scores awarded by the adjudicators. Methods: Six high-level and six intermediate dance couples took part in the study. Each couple performed three identical series of three natural turns figure in the Viennese waltz. All of them were recorded on camera while performing to music. All the trials of each couple were evaluated by 6 international adjudicators as to the technical quality component from the Absolute Judging System. A device for measuring triaxial rotational angular velocities was mounted on the dorsal part of the pelvic girdle and on the back of the chest of each athlete. Results: An analysis of covariance revealed that the mean squares of the difference in angular rotation velocity of the pelvic girdle and thoracic spine of the tested dancers were strongly associated with scores given by the adjudicators (F1.9 = 11.5, p = 0.0240, np2 = 0.449) independently of the assignment to the given group. Conclusions: The analysis and comparison of top level and intermediate athletes showed that the suggested method of measurement, presentation and analysis of the profile motion of pelvic girdle and chest motion may become a good tool for a general evaluation of the movement technique as well as a quick and effective qualitative and quantitative biomechanical assessment of selected components of movement technique in dancesport.

8

On the improvement of calibration accuracy of parallel robots – modeling and optimization

88%

Bentaleb T. , Iqbal J.

Journal of Theoretical and Applied Mechanics

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2020

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tom Vol. 58 nr 1

261--272

EN

This paper proposes kinematic based calibration methods for Delta parallel robots. The boundary of the robot workspace is computed using a forward kinematic model. Influence of errors in kinematic parameters on the workspace boundaries is investigated. The novelty of the proposed approach lies in Jacobian-based computation of kinematic models. Also, the present work extends and applies the existing calibration methods traditionally meant for serial robots on the Delta robot. These methods include the forward method and the inverse method. Simulation results confirm the efficacy of the proposed calibration strategies.

9

A kinematic model of a humanoid lower limb exoskeleton with pneumatic actuators

88%

Głowiński S. , Ptak M.

Acta of Bioengineering and Biomechanics

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2022

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tom Vol. 24, no. 1

145--157

EN

Although it is well-established that exoskeletons as robots attached to the human body's extremities increase their strength, limited studies presented a computer and mathematical model of a human leg pneumatic exoskeleton based on anthropometric data. Methods: By using Inertial Measurement Units a lower limb joint angles (hip, knee and ankle in sagittal plane) during walking and running were calculated. The geometric model of a human leg pneumatic exoskeleton was presented. Joint angle data acquired during experiments were used in the mathematical model. Results: The position and velocity of exoskeleton actuators in each phase of the movement were calculated using the MATLAB package (Matlab_R2017b, The MathWorks Company, Novi, MI, USA). Conclusions: The obtained results demonstrate the efficiency of the proposed approach that can be utilized to analyze the kinematics of pneumatic exoskeletons using the dedicated design process. The developed mathematical model makes it possible to determine the position of lower limb segments and exoskeleton elements. The proposed model allows for calculating the position of the human leg and actuators' characteristic points.

10

Kinematic Control of a Mobile Robot Performing Manufacturing Tasks on Non-Planar Surfaces

88%

Qualls J. , Canfield S. , Shibakov A.

Journal of Automation Mobile Robotics and Intelligent Systems

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2016

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tom Vol. 10, No. 3

12--21

EN

Mobile robotic systems are becoming viable technologies for automating manufacturing processes in fields that traditionally have seen little automation. Such fields include pipeline construction, green energy development, infrastructure and shipbuilding. To operate in these environments, the mobile robotic platform must provide controlled motion of a manufacturing toolset over the surface of a structure which is generally non-planar. One such example is welding a seam along a non-flat ship hull where the surface may consist of sections resembling common geometric shapes such as cylinders or spheres and the tool must follow a path defined by the weld seam. This paper will present a kinematic control approach applicable to one mobile robot topology performing a task on a cylindrical surface. This method is readily generalized to other robot topologies or surface geometries. The method is based on a kinematic model that predicts the robot motion and configuration joint parameters while on a nonplanar surface with the desired motion prescribed in local tool space. The effort is motivated by a practical application of welding on steel hulls or other surfaces and the results will be compared with these empirical experiences. A discussion of how these results can be used to guide future design of mobile robot platforms for manufacturing is provided.

11

Work Package 7 of CERGOP-2/Environment: geo-kinematical modelling and strain analysis, activity report April-September 2003

75%

Hefty J.

Reports on Geodesy

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2003

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tom z. 3/66

63-65

12

Some results obtained from three dimensional plate kinematics analyses in Romania-(1997-2000)

75%

Ghitău D.

Reports on Geodesy

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2003

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tom z. 3/66

91-106

13

Walcowanie gwintu dwiema rolkami metodą styczną

75%

Łyczko K.

Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją

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2004

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tom Nr 1

47-51

PL

Artykuł dotyczy technologii walcowania gwintów zewnętrznych przy stycznym posuwie rolek w stosunku do powierzchni gwintowanej. Przedstawiono w nim kinematyczne zależności w układzie między rolkami oraz rolkami a przedmiotem obrabianym. Omówiono dobór parametrów obróbki i metodykę obliczania wymiarów rolek walcujących.

EN

Technology of rolling external threads at tangential feed of rollers in relation to threading surface has been presented. Kinematic relationships in rollers system and between roller and object system has been discussed. Selection of treatment parameters, methodology of calculating of thread rollers dimensions have been also presented.

14

Static and kinematic experiments on EGNOS

75%

Cefalo R. , Gatti M. , Sluga T.

Reports on Geodesy

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2002

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tom z. 3/63

87-103

EN

Since February 2000, various static and kinematic tests have been performed at the Department of Civil Engineering, University of Trieste and Department of Engineering, University of Ferrara, to analyse the achievable positioning accuracies using the WADGPS (Wide Area Differential GPS) corrections transmitted by Geostationary Satellites. In this paper, we report the most resent experiments using the ESTB(EGNOS System Test Bed) SIS (Signal In Space) from the Inmarsat III AOR-E Geostationary Satellite in static and kinematic mode, together with a static test using the WAAS (Wide Area Augmentation System) signal the Inmarsat III AOR-W Geostationary Satellite.

15

Slope stability analysis in open pit mines of Jebel Gustar career, NE Algeria – a multi-steps approach

75%

Zahri F. , Boukelloul M. L. , Hadji R. , Talhi K.

Mining Science

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2016

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tom Vol. 23

137--146

EN

Several types of instabilities can menace the personnel and equipment in the open cast mines. Their kinematicis dependent commonly on the nature, the structure, the fracturing and the strength of the rock mass. A scientific assessment vis-a-vis their equilibrium is suggested. For this task a considerable amount of field work must already carrying out to supply the necessary data ie: geometric, mechanic and geologic parameters. The main purpose of this research is identifying different modes of slope failures that may develop on the career “ENOF” of Jebel Gustar, by a multi-step analysis. For this task, i) a structural analysis; ii) an estimation of the rock mass and discontinuity mechanical properties, iii) a rating of the rock mass quality, iv) and a numerical simulation of the stability are procedurally used. The results matched well with the field observations. They proved the poor stability of the career, showing a typical example of a bad slope-design. The application of such approaches can help stabilizing the mine and ensure the safety and a sustainable production.

16

Kinematic-PPP using single/dual frequency observations from (GPS, GLONASS and GPS/GLONASS) constellations for hydrography

75%

Farah A.

Artificial Satellites : Journal of Planetary Geodesy

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2018

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tom Vol. 53, No. 1

37--46

EN

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS’s contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

17

Relationship between performance, dry-land power and kinematics in master swimmers

75%

Espada M. C. , Costa M. J. , Costa A. M. , Silva A. J. , Barbosa T. M. , Pereira A. F.

Acta of Bioengineering and Biomechanics

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2016

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tom Vol. 18, no. 2

145--151

EN

The purpose of the study was to analyze the relationships between sprint swimming performance, dry-land power, and kinematics in master swimmers. Twenty-two male master swimmers were separated in two groups based on their chronological age: (i) 30–39 years and; (ii) 40–49 years. Maximum dry-land power was determined through counter movement jump and 3 kg medicine ball throwing (Hmax and Tmax, respectively). Kinematic determinants of performance were measured during a maximal bout of 15, 25 and 50 m front crawl (T15, T25, T50). Stroke frequency (SF), stroke length (SL) and stroke index (SI) were calculated as kinematical aspects of the stroke. In the 30-39 group, SI25 was correlated to T25 (r = –0.76, p < 0.01, η2 = 0.96), the same was observed between SI50 and T50 (r = –0.83, p < 0.01, η2 = 0.96). Only SI50 was significantly correlated to T50 (r = –0.86, p < 0.01, η2 = 0.97) in the 40–49 years age cohort. In dryland power variables, Hmax and Tmax were only correlated in the younger master swimmers group (r = –0.87, p < 0.01, η2 = 0.97). There were no significant differences (p < 0.05) between younger (30–39 years) and older (40–49 years) swimmers groups in dry-land tests (Hmax 28.5 ± 5.9 vs. 26.5 ± 3.9 cm and Tmax 4.2 ± 1.0 vs. 4.2 ± 1.1 m). Our results suggest that swimming performance in younger master swimmers (30–39 years) seem more dependent on kinematic swimming variables than on strength parameters, which were most related to swimming performance in the older master swimmers (40–49 years).

18

Analiza kinematyki ruchów kończyny górnej podczas wykonywania ćwiczeń rehabilitacyjnych metodą PNF

63%

Michnik R. , Jurkojc J. , Rak Z. , Mężyk A. , Paszenda Z. , Rycerski W. , Janota J. , Brandt J.

Modelowanie Inżynierskie

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2008

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tom T. 5, nr 36

243-248

PL

W ramach pracy przeprowadzono badania kinematyki ruchów kończyny górnej wykonywanych podczas ćwiczeń rehabilitacyjnych tzw. metod PNF (Prioproceptive Neuromuscular Facilitation). Badania zrealizowano przy pomocy systemu do analizy ruchu APAS. Ruchy wykonywane przez fizjoterapeutę rejestrowane były przez zestaw siedmiu kamer cyfrowych firmy. Basler. Przebiegi kinematyczne charakterystycznych punktów antropometrycznych zostały poddane dalszej obróbce w autorskim programie TRAJGEN, w celu wyznaczenia położeń środków poszczególnych stawów kończyny górnej oraz określenie przemieszczeń kątówych poszczególnych segmentów. Wyniki uzyskane w pracy znalazły zastosowanie przy opracowywaniu konstrukcji projektowanego urządzenia rehabilitacyjnego.

EN

Research into kinematic analysis of the upper limb motion during exercises caring out according to the PNF (Prioproceptive Neuromuscular Facilitation) method is presented in the paper. Research was realised with the help of the APAS System. All movements, performed by physiotherapeutist, were recorded by seven, suitably placed, Basler camcorders. Kinematic courses of characteristic anthropometrics points, were processed in the TRAJGEN computer program in order to determine centres of individual joints of the upper limb and angle displacements of individual segments. Results were used during designing process of rehabilitation device.

19

Kinematic analysis of the finger exoskeleton using MATLAB/Simulink

63%

Nasiłowski K. , Awrejcewicz J. , Lewandowski D.

Acta of Bioengineering and Biomechanics

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2014

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tom Vol. 16, no. 3

129--134

EN

A paralyzed and not fully functional part of human body can be supported by the properly designed exoskeleton system with motoric abilities. It can help in rehabilitation, or movement of a disabled/paralyzed limb. Both suitably selected geometry and specialized software are studied applying the MATLAB environment. A finger exoskeleton was the base for MATLAB/Simulink model. Specialized software, such as MATLAB/Simulink give us an opportunity to optimize calculation reaching precise results, which help in next steps of design process. The calculations carried out yield information regarding movement relation between three functionally connected actuators and showed distance and velocity changes during the whole simulation time.

20

Modelling of the joint kinematics in the external fixation

63%

Jasińska-Choromańska D. , Choromański W.

Zeszyty Naukowe Politechniki Poznańskiej. Maszyny Robocze i Transport

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2002

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tom Nr 54

109-114

EN

Methods of healing fractures belong undoubtedly to the oldest group in the history of medicine. Yet, there are still carried out intensive studies related to searching for new methods as well as perfecting of the existing ones. One of them is unquestionably the external osteosynthesis with application of external orthopaedic fixators. It has been well known for a long time that providing micro-movements within the interstice of the fracture favours the progress of the bone union processes by stimulating growth of the callus. The motion is very significant while healing joint fractures or periarthric fractures. Because of a difficulty in reflecting kinematics of the knee joint for the purpose of external fixation, the paper presents a proposal of an analytic-experimental method that allows for a simple achievement of this goal.

PL

Praca poświęcona jest modelowaniu kinematyki stawów ludzkich. Celem badań jest projektowanie elementów ortopedycznych stabilizatorów zewnętrznych , które mogą odwzorowywać ruch stawów ludzkich. Szczególna uwaga zwrócona została na staw kolanowy. Stabilizatory wyposażone w takie układy znacząco przyspieszają zrost i eliminują powikłania w leczeniu złamań okołostawowych.