Kinematic Perturbation in the Flexion-Extension Axis for Two Lumbar Rigs During a High Impact Jump Task

2011 ◽  
Vol 27 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Marc R. Portus ◽  
David G. Lloyd ◽  
Bruce C. Elliott ◽  
Neil L. Trama
Keyword(s):  
High Impact ◽  
Fast Fourier Transformation ◽  
Signal Power ◽  
Motion Data ◽  
Flexion Extension ◽  
Spine Motion ◽  
Analysis System ◽  
Impact Phase ◽  
Base Of Support ◽  
The Impact

The measurement of lumbar spine motion is an important step for injury prevention research during complex and high impact activities, such as cricket fast bowling or javelin throwing. This study examined the performance of two designs of a lumbar rig, previously used in gait research, during a controlled high impact bench jump task. An 8-camera retro-reflective motion analysis system was used to track the lumbar rig. Eleven athletes completed the task wearing the two different lumbar rig designs. Flexion extension data were analyzed using a fast Fourier transformation to assess the signal power of these data during the impact phase of the jump. The lumbar rig featuring an increased and pliable base of support recorded moderately less signal power through the 0–60 Hz spectrum, with statistically less magnitudes at the 0–5 Hz (p= .039), 5–10 Hz (p= .005) and 10–20 Hz (p= .006) frequency bins. A lumbar rig of this design would seem likely to provide less noisy lumbar motion data during high impact tasks.

Assessment of Workspace Attributes Under Simulated Index Finger Proximal Interphalangeal Arthrodesis

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Paul G. Arauz ◽  
Sue A. Sisto ◽  
Imin Kao
Keyword(s):  
Index Finger ◽  
Model Parameters ◽  
System Parameters ◽  
System A ◽  
Flexion Extension ◽  
Pip Joint ◽  
Interphalangeal Arthrodesis ◽  
Analysis System ◽  
The Impact ◽  
Proximal Interphalangeal Arthrodesis

This article presented an assessment of quantitative measures of workspace (WS) attributes under simulated proximal interphalangeal (PIP) joint arthrodesis of the index finger. Seven healthy subjects were tested with the PIP joint unconstrained (UC) and constrained to selected angles using a motion analysis system. A model of the constrained finger was developed in order to address the impact of the inclusion of prescribed joint arthrodesis angles on WS attributes. Model parameters were obtained from system identification experiments involving flexion–extension (FE) movements of the UC and constrained finger. The data of experimental FE movements of the constrained finger were used to generate the two-dimensional (2D) WS boundaries and to validate the model. A weighted criterion was formulated to define an optimal constraint angle among several system parameters. Results indicated that a PIP joint immobilization angle of 40–50 deg of flexion maximized the 2D WS. The analysis of the aspect ratio of the 2D WS indicated that the WS was more evenly distributed as the imposed PIP joint constraint angle increased. With the imposed PIP joint constraint angles of 30 deg, 40 deg, 50 deg, and 60 deg of flexion, the normalized maximum distance of fingertip reach was reduced by approximately 3%, 4%, 7%, and 9%, respectively.

Kinematic Landing Strategy Transference in Backward Rotating Gymnastic Dismounts

2013 ◽  
Vol 29 (3) ◽  
pp. 253-260 ◽  
Author(s):  
Marianne J.R. Gittoes ◽  
Gareth Irwin ◽  
David G. Kerwin
Keyword(s):  
Body Orientation ◽  
Whole Body ◽  
Phase Duration ◽  
Joint Kinematic ◽  
Joint Strategy ◽  
Analysis System ◽  
Kinematic Measures ◽  
Impact Phase ◽  
Female Gymnasts ◽  
The Impact

The aim of this study was to develop insight into the transference of kinematic landing strategies between backward rotating dismount skills. Female gymnasts performed backward rotating pike (N = 4 × 10 trials) and tuck dismounts skills (N = 4 × 10 trials) from the beam apparatus. Whole and lower body joint kinematic measures were quantified for the impact phase using an automatic motion analysis system (CODAMotion, Charnwood Dynamics Ltd.). Phase duration, whole body orientation and the mass center maximum z-displacement were similar (P< .01) between skills for individual gymnasts and the group. While skill differences in the hip joint motion profiles were notably larger (group root mean squared difference [RMSD]: 30.9%) than the ankle (group RMSD: 13.6%) and knee (group RMSD: 15.4%) joints, individual gymnast adjustments were made to the discrete joint kinematic measures. The use of a stable whole body orientation may provide important indicators of effective strategy transference between fundamental dismount skills. Further consideration of the joint strategy adjustments made according to the gymnast’s performance level may, however, be warranted.

Larvae of the blow fly Caiusa testacea (Diptera: Calliphoridae) as egg predators of Polypedates cruciger Blyth, 1852 (Amphibia: Anura: Rhacophoridae)

2020 ◽  
Vol 12 (17) ◽  
pp. 17374-17379
Author(s):  
W.G.D. Chathuranga ◽  
K. Kariyawasam ◽  
Anslem De Silva ◽  
W.A.Priyanka P. De Silva
Keyword(s):  
Sri Lanka ◽  
High Impact ◽  
Tree Frog ◽  
Blow Fly ◽  
Breeding Habitats ◽  
The Family ◽  
Water Container ◽  
The Common ◽  
Natural Breeding ◽  
The Impact

We investigated the impact of dipteran predators on eggs in foam nests of the Common Hour-glass Tree Frog Polypedates cruciger Blyth, 1852 (Anura: Rhacophoridae) in central Sri Lanka.  Foam nests (n=24) of P. cruciger were examined at their natural breeding habitats and infected (n=8) and uninfected spawns (n=16) were identified.  Emerging tadpoles were collected in a water container hung under each spawn and the average number of tadpoles (N) hatched from infected spawns (N=0) was compared with that of uninfected spawns (N=354 ± 67).  Three severely infected spawns were brought to the laboratory and the fly larvae were reared until they metamorphosed to adults.  Morphological and molecular identification of the flies confirmed them as belonging to Caiusa testacea Senior-White, 1923 of the family Calliphoridae.  The infected spawns were completely destroyed and an estimated average of 400 P. cruciger eggs per spawn were lost.  The results revealed a high impact of Caiusa testacea on egg and embryo mortality of P. cruciger.

scholarly journals The Effects of Repetitive Drop Jumps on Impact Phase Joint Kinematics and Kinetics

2011 ◽  
Vol 27 (2) ◽  
pp. 108-115 ◽  
Author(s):  
Joshua T. Weinhandl ◽  
Jeremy D. Smith ◽  
Eric L. Dugan
Keyword(s):  
Energy Absorption ◽  
Plantar Flexion ◽  
Knee Extension ◽  
Joint Kinematics ◽  
Knee Extensors ◽  
Initial Contact ◽  
Drop Jumps ◽  
Impact Phase ◽  
The Impact ◽  
Kinematics And Kinetics

The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n= 6) and females (n= 6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100 ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantar flexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantar flexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.

scholarly journals Evolution of mantis shrimp telson armour and its role in ritualized fighting

2019 ◽  
Vol 16 (157) ◽  
pp. 20190203 ◽  
Author(s):  
Jennifer R. A. Taylor ◽  
Nina I. Scott ◽  
Greg W. Rouse
Keyword(s):  
Comparative Analysis ◽  
Impact Resistance ◽  
High Impact ◽  
Mantis Shrimp ◽  
Impact Forces ◽  
Drop Tests ◽  
Impact Parameters ◽  
Ritualized Combat ◽  
Stiff Spring ◽  
The Impact

Mantis shrimp possess both formidable weapons and impact-resistant armour that clash during ritualized combat. The telson is one of few biological structures known to withstand the repeated high impact forces of smashing mantis shrimp strikes, and it is hypothesized that this pairing of armour and weapon is associated with the evolution of telson sparring. We carried out a comparative analysis of telson impact mechanics across 15 mantis shrimp species to assess if the telsons of sparring species (i) are consistently specialized for impact-resistance, (ii) are more impact-resistant than those of non-sparring species, and (iii) have impact parameters that correlate with body size, and thereby useful for assessment. Our data from ball drop tests show that the telsons of all species function like a stiff spring that dissipates most of the impact energy, but none of the measured impact parameters are correlated with the occurrence of sparring behaviour. Impact parameters were correlated with body mass for only some species, suggesting that it is not broadly useful for size assessment during ritualized fighting. Contrary to expectation, sparring mantis shrimp do not appear to have coevolved telson armour that is more robust to impact than non-sparring species. Rather, telson structure is inherently impact-resistant.

scholarly journals Impact of accelerometer based in physical layer wireless networks

2018 ◽  
Vol 7 (2.5) ◽  
pp. 15
Author(s):  
Zuhanis Mansor ◽  
Muhammad Khairulanwar bin Zulkafli
Keyword(s):  
Wireless Communication ◽  
Landscape Position ◽  
Line Of Sight ◽  
Noise Power ◽  
Signal Power ◽  
Propagation Channel ◽  
Signal To Noise ◽  
Downlink Throughput ◽  
The Impact ◽  
Non Line Of Sight

The initial deployments of antenna in the handset consist of fixed non-rotated antenna for transmitting and receiving the signal in the wireless communication scenario. However, link correlation at the UE shows very bad performance when the handset rotates in landscape position. This paper evaluates the impact of accelerometer on the downlink propagation channel of 3G smartphone for non-line-of-sight links. The performance average received signal power is studied for user equipment. Results show that the exploitation of an accelerometer provide better performance in terms of received signal power when the handset rotated from portrait to landscape position. It can be concluded that the deployment of accelerometer can be used to improve existing 3G smartphone received signal. Results also indicate that accelerometer can be used to improve downlink throughput since the signal-to-noise-power is increased by approximately 16%.

scholarly journals Research on the specific movement of the head in tennis strokes

2020 ◽  
Vol 28 (80) ◽  
pp. 16-19
Author(s):  
Manuel Fernández López
Keyword(s):  
Tennis Player ◽  
Effective Technique ◽  
The Gaze ◽  
Impact Phase ◽  
Player Performance ◽  
The Impact

Technique is one of the aspects that has the most relevant influence on tennis player performance. Searching for more efficient and effective technique, by means of the application of biomechanical laws, is a constant among coaches and researchers. This article deals with a very concrete subject in tennis technique: the position of the head during the impact phase of tennis strokes. Biomechanical aspects of the strokes will also be considered, as well as other relevant aspects such as fixing the gaze during the stroke and the stretching-shortening cycle.

scholarly journals Karakterisasi Mekanik Komposit Matriks Polipropilena High Impact Dengan Serat Alam Acak Dengan Metode Hand Lay Up Untuk Komponen Automotive

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Alfan Ekajati Latief ◽  
Nuha Desi Anggraeni ◽  
Dedy Hernady
Keyword(s):  
Tensile Strength ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Natural Fibers ◽  
Mesh Size ◽  
High Impact ◽  
Hemp Fiber ◽  
Polypropylene Matrix ◽  
The Impact ◽  
Pineapple Leaves

ABSTRAK Serat alam yang berfungsi sebagai penguat memiliki sifat yang lebih ringan, mudah dibentuk, tahan korosi, harga murah dan memiliki kekuatan yang sama dengan material logam. Serat bahan alami yang memiliki kekuatan tarik, tekan dan impak yang baik diantaranya serat rami dan daun nanas. Untuk matriks Polipropilena high impact (PPHI) yang banyak digunakan dalam industri otomotif.. Pada penelitian ini dipelajari pengaruh fraksi volume serat alami terhadap sifat mekanik komposit PPHI berpenguat serat alami. Komposit PPHI dibuat dengan menggunakan metode Hand Lay Up pada temperatur 2500C dengan fraksi volume serat alami sebesar 10%, dimana serat dibuat digunting halus hingga memiliki ukuran mesh 120/170, 170/200 dan dibawah 200 mesh, Kekuatan tarik komposit diukur dengan mengacu pada standar ASTM 3039, kekuatan tekan diukur mengacu pada ASTM D 695. Harga Impak dari komposit diukur dengan mengacu pada ASTM D 6110-04. Pada penelitian ini dapat disimpulkan, fraksi volume 10 % serat alami yang baik ketika dicampur dengan matriks polipropilena high impact adalah serat nanas dengan meshing 170/200 dapat meningkatkan kekuatan tarik PPHI sebesar 40 % dan meningkatkan harga impak PPHI sebesar 50,8 % jika dilihat penelitan sebelumnya yakni menggunakan serat rami dibawah mesh 1200 dengan matriks PPHI. Kata Kunci: Rami, Daun Nanas, Polipropilena High Impact, Hand Lay Up. ABSTRACT Natural fibers that function as reinforcement have lighter properties, are easily formed, are corrosion resistant, are cheap and have the same strength as metal materials. Natural fiber which has good tensile, compressive and impact strength including Ramie and pineapple leaves. For high impact polypropylene matrix (PPHI) which is widely used in the automotive industry. In this study the effect of volume fraction of natural fibers on the mechanical properties of PPHI composites with natural fiber reinforced properties was studied. PPHI composites are made using the Hand Lay Up method at a temperature of 2500C with a volume fraction of natural fibers of 10%, where fibers are made finely shaved to have a mesh size of 120/170, 170/200 and below 200 mesh, the tensile strength of the composite is measured by reference to the standard ASTM 3039, compressive strength measured refers to ASTM D 695. The impact price of the composite is measured with reference to ASTM D 6110-04. In this study it can be concluded, a good volume fraction of 10% natural fiber when mixed with high impact polypropylene matrix is pineapple fiber with meshing 170/200 can increase the tensile strength of PPHI by 40% and increase the impact price of PPHI by 50.8% if seen by research previously that used hemp fiber under mesh 1200 with PPHI matrix. Keywords: Ramie Pineapple, High Impact Polypropylene, Hand Lay Up.

scholarly journals Empirical Analysis of the Impact Strength of Textile Knitted Barrier Meshes

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zbigniew Mikołajczyk ◽  
Beata Szałek ◽  
Katarzyna Pieklak
Keyword(s):  
Measurement Data ◽  
Test Stand ◽  
Dynamic Loads ◽  
Measuring System ◽  
Electronic Measuring ◽  
Computer Data ◽  
Analysis System ◽  
Data Analysis System ◽  
Dynamic Stress Distribution ◽  
The Impact

AbstractThe assumptions of instrumental methodology for measuring dynamic loads of knitted barrier meshes were defined. A test stand was built, original in terms of both mechanical construction and electronic measuring system, connected to a computer data analysis system. Maximum values of dynamic forces in the mesh fastening strings were determined. The correctness of the strain gauges construction and measurement data transmission systems was confirmed. Tests of multidirectional resistance to dynamic loads in the mesh fastening strings were carried out. The experiment involved dropping a ball with a mass of 5 kg and a diameter of 10 cm, from a height of 1 m and 2 m onto the mesh surface. The potential impact energy equaled Ep1 = 49.05 J and Ep2 = 98.1 J. The tests showed that the highest force values were observed for meshes with square-shaped a-jour structure, and for mesh with diamond-shaped a-jour geometry the force values were lower. A symmetrical forces distribution was observed in all the strings. The highest forces were recorded in the middle strings and the lowest in the outer ones. The conducted tests confirmed the correctness of the adopted constructional solutions of test stand for identification of dynamic stress distribution in mesh fastening strings. The developed method is a useful verification tool for numerical analysis of mechanical properties of barrier meshes.

scholarly journals Characterization of Modern and Historical Seismic–Tsunamic Events, and Their Global–Societal Impacts

2021 ◽  
pp. SP501-2021-17
Author(s):  
Yildirim Dilek ◽  
Yujiro Ogawa ◽  
Yasukini Okubo
Keyword(s):  
Disaster Management ◽  
Plate Tectonics ◽  
Power Plants ◽  
Active Faults ◽  
Building Design ◽  
Developed Countries ◽  
High Impact ◽  
Global Banking ◽  
Management Plans ◽  
The Impact

AbstractEarthquakes and tsunamis are high–impact geohazard events that could be extremely destructive when they occur at large magnitudes and intensities, respectively, although their causes and potential locations are, for the most part, predictable within the framework of plate tectonics. Amongst the main reasons for their high impact include enormous numbers of casualties, extensive property damage in vast areas, and significant social and economic disruptions in urban settings where populous residential areas, global banking centres, industrial factories, and critical facilities (nuclear power plants, dams) may be located. In order to reduce the impact of these geohazards, the nations, societies, professional organizations and governments need to collaborate to prepare more effective seismic and tsunami risk assessments, disaster management plans, educational and training programmes for increased preparedness of the public, and strategic plans and objectives for capacity building, skill and knowledge transfer, and building of societal resilience. Improved building design and construction codes, and emergency preparedness and evacuation plans should be part of disaster management plans in countries where destructive earthquakes and tsunamis occurred earlier. Fast increasing population in coastal corridors in developing and developed countries is likely to escalate the social and economic impacts of these geohazards exponentially in the future. The chapters in this book present case studies of some of the most salient earthquake and tsunami events in historical and modern times, their origins and manifestations, and efforts and most effective practices of risk assessment and disaster management implemented by various governments, international organizations and inter–governmental agencies following these events. New methods of computing probabilistic seismic hazard risks, delineating respect distance and damage zones along–across seismically active faults and recognizing tsunamigenic and submarine landslides on the seafloor are introduced. The conclusions presented in the chapters show that: (1) scientific understanding of the characteristics of seismically active faults is paramount; (2) increased local (community), national and global resilience is necessary to empower societal preparedness for earthquake and tsunami events; and, (3) all stakeholders, including policy–makers, scientists, local, state and national governments, media, and world organizations (UNESCO, IUGS, GeoHazards International–GHI, Global Geodetic Observing System–GGOS; National Earthquake Hazards Reduction Program–NEHRP) must work together to disseminate accurate and timely information on geohazards, to develop effective legislation for risk reduction, and to prepare realistic and practical hazard mitigation and management measures.

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