scholarly journals An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2190 ◽  
Author(s):  
Sarah Jane Hobbs ◽  
John E.A. Bertram ◽  
Hilary M. Clayton
Keyword(s):  
Mechanical Energy ◽  
Reaction Force ◽  
Strong Relationship ◽  
Energy Losses ◽  
Collision Dynamics ◽  
Centre Of Pressure ◽  
Kinematic Data ◽  
Speed Range ◽  
Distribution Moment ◽  
Insight Into

Background.Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals.Methods.The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters.Results.Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P= .001) from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04) through synchronous (0.36 ± 0.02) to a more cranial location in fore-first dissociation (0.32 ± 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R= .594;P< .01) and speed (R= .789;P< .01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R= .085;P> 0.05) or speed (R= .223;P= .023).Discussion.The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

scholarly journals An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

2016 ◽  
Author(s):  
Sarah Jane Hobbs ◽  
John E A Bertram ◽  
Hilary M Clayton
Keyword(s):  
Mechanical Energy ◽  
Reaction Force ◽  
Strong Relationship ◽  
Energy Losses ◽  
Collision Dynamics ◽  
Centre Of Pressure ◽  
Kinematic Data ◽  
Speed Range ◽  
Distribution Moment ◽  
Insight Into

Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, 5 horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P=.001) from being more caudally located in hind-first dissociation (mean location = 0.41±0.04) through synchronous (0.36±0.02) to a more cranial location in fore-first dissociation (0.32±0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R=.594; P<.01) and speed (R=.789; P<.01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R=.085; P>.05) or speed (R=.223; P=.023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

scholarly journals An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

2016 ◽  
Author(s):  
Sarah Jane Hobbs ◽  
John E A Bertram ◽  
Hilary M Clayton
Keyword(s):  
Mechanical Energy ◽  
Reaction Force ◽  
Strong Relationship ◽  
Energy Losses ◽  
Collision Dynamics ◽  
Centre Of Pressure ◽  
Kinematic Data ◽  
Speed Range ◽  
Distribution Moment ◽  
Insight Into

Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, 5 horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P=.001) from being more caudally located in hind-first dissociation (mean location = 0.41±0.04) through synchronous (0.36±0.02) to a more cranial location in fore-first dissociation (0.32±0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R=.594; P<.01) and speed (R=.789; P<.01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R=.085; P>.05) or speed (R=.223; P=.023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

Investigation of Thermal Effects in Direct Driven Hydraulic System for Off-Road Machinery

2016 ◽  
Author(s):  
Niko Karlén ◽  
Tatiana Minav ◽  
Matti Pietola
Keyword(s):  
Energy Efficiency ◽  
Hydraulic System ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Hydraulic Model ◽  
Energy Losses ◽  
Total Efficiency ◽  
Ambient Temperatures ◽  
Wheel Loaders ◽  
Save Energy

Several types of off-road machinery, such as industrial trucks, forklifts, excavators, mobile cranes, and wheel loaders, are set to be operated in environments which can differ considerably from each other. This sets certain limits for both the drive transmissions and working hydraulics of these machines. The ambient temperature must be taken into account when selecting the hydraulic fluid since the viscosity and density of the fluid are changing at different operating temperatures. In addition to the temperature, energy efficiency can also be a problem in off-road machinery. In most off-road machines, diesel engines are employed to produce mechanical energy. However, there are energy losses during the working process, which causes inefficiency in produced energy. For better energy efficiency, hybridization in off-road machinery is an effective method to decrease fuel consumption and increase energy savings. One of the possible methods to save energy with hybrids is energy regeneration. However, it means that the basic hydraulic system inside off-road machinery needs to be modified. One solution for this is to utilize zonal or decentralized approach by means of direct driven hydraulic (DDH) system. This paper aims to investigate a DDH system for off-road machinery by means of modelling and analyzing the effect of the temperature. In the direct-driven hydraulic system, the actuator is controlled directly by the hydraulic pump which is operated by the electric motor. Specifically, it is a valveless closed-loop hydraulic system. Thus, there will be no energy losses caused by the valves, and the total efficiency is assumed to be significantly higher. In order to examine the DDH system, a thermo-hydraulic model was created. Additionally, a thermal camera was utilized in order to illustrate the temperature changes in the components of the DDH system. To reproduce the action of the system in different circumstances DDH system was run at different ambient temperatures, and the component temperatures in the system were measured and saved for the analysis. The thermo hydraulic model was proven capable to follow the general trend of heating up.

A new insight into ZIF-67 based triboelectric nanogenerator for self-powered robot object recognition

2021 ◽  
Author(s):  
Sugato Hajra ◽  
Manisha Sahu ◽  
Aneeta Manjari Padhan ◽  
Jaykishon Swain ◽  
Basanta Kumar Panigrahi ◽  
...  
Keyword(s):  
Object Recognition ◽  
Mechanical Energy ◽  
Power Source ◽  
Triboelectric Nanogenerator ◽  
Electrostatic Induction ◽  
Self Powered ◽  
Insight Into

Harvesting mechanical energy from surroundings can be a promising power source for micro/nano-devices. The triboelectric nanogenerator (TENG) works in the principle of triboelectrification and electrostatic induction. So far, the metals...

Mechanics of a rapid running insect: two-, four- and six-legged locomotion

1991 ◽  
Vol 156 (1) ◽  
pp. 215-231 ◽  
Author(s):  
R. J. Full ◽  
M. S. Tu
Keyword(s):  
Periplaneta Americana ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Reaction Force ◽  
Metabolic Cost ◽  
Legged Locomotion ◽  
American Cockroach ◽  
Stride Frequency ◽  
Gravitational Potential Energy ◽  
Vertical Ground Reaction Force

To examine the effects of variation in body form on the mechanics of terrestrial locomotion, we used a miniature force platform to measure the ground reaction forces of the smallest and, relative to its mass, one of the fastest invertebrates ever studied, the American cockroach Periplaneta americana (mass = 0.83 g). From 0.44-1.0 ms-1, P. americana used an alternating tripod stepping pattern. Fluctuations in gravitational potential energy and horizontal kinetic energy of the center of mass were nearly in phase, characteristic of a running or bouncing gait. Aerial phases were observed as vertical ground reaction force approached zero at speeds above 1 ms-1. At the highest speeds (1.0-1.5 ms-1 or 50 body lengths per second), P. americana switched to quadrupedal and bipedal running. Stride frequency approached the wing beat frequencies used during flight (27 Hz). High speeds were attained by increasing stride length, whereas stride frequency showed little increase with speed. The mechanical power used to accelerate the center of mass increased curvilinearly with speed. The mass-specific mechanical energy used to move the center of mass a given distance was similar to that measured for animals five orders of magnitude larger in mass, but was only one-hundredth of the metabolic cost.

scholarly journals Mean-Field Magnetohydrodynamics as a Basis of Solar Dynamo Theory

1976 ◽  
Vol 71 ◽  
pp. 323-344 ◽  
Author(s):  
K.-H. Rädler
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Mean Field ◽  
Strong Relationship ◽  
Solar Radius ◽  
Small Scale ◽  
Dynamo Theory ◽  
The Magnetic Field ◽  
Complicated Situation ◽  
Insight Into

One of the most striking features of both the magnetic field and the motions observed at the Sun is their highly irregular or random character which indicates the presence of rather complicated magnetohydrodynamic processes. Of great importance in this context is a comprehension of the behaviour of the large scale components of the magnetic field; large scales are understood here as length scales in the order of the solar radius and time scales of a few years. Since there is a strong relationship between these components and the solar 22-years cycle, an insight into the mechanism controlling these components also provides for an insight into the mechanism of the cycle. The large scale components of the magnetic field are determined not only by their interaction with the large scale components of motion. On the contrary, a very important part is played also by an interaction between the large and the small scale components of magnetic field and motion so that a very complicated situation has to be considered.

Tadpole: A Design Problem in the Mechanics of the Use of Sea Wave Energy

1996 ◽  
Vol 210 (4) ◽  
pp. 273-277 ◽  
Author(s):  
M J French
Keyword(s):  
Wave Energy ◽  
Special Interest ◽  
Reaction Force ◽  
Electrical Energy ◽  
Wave Forces ◽  
Sea Waves ◽  
Small Machine ◽  
Clear Insight ◽  
Insight Into ◽  
Sea Wave

A study is made of a device for obtaining electrical energy from sea waves, in which the problem of providing a reaction against the wave forces is met by a combination of a pendulum and gyroscopes. The mechanics is developed in a logical manner which gives a clear insight into the function, the pendulum providing the reaction force, which leaves an unbalanced moment to be countered by the gyroscopes, which also constitute the power take-off. The result is a relatively small machine with no external moving parts. The treatment requires no understanding of wave hydrodynamics. It is felt this paper may be of special interest as a design study, in which the relation between the mechanics and the development of the concept is peculiarly cogent.

scholarly journals The series elastic shock absorber: tendon elasticity modulates energy dissipation by muscle during burst deceleration

2015 ◽  
Vol 282 (1804) ◽  
pp. 20142800 ◽  
Author(s):  
Nicolai Konow ◽  
Thomas J. Roberts
Keyword(s):  
Energy Dissipation ◽  
Shock Absorber ◽  
Mechanical Energy ◽  
Reaction Force ◽  
Drop Height ◽  
Fascicle Length ◽  
Tendon Mechanics ◽  
Rapid Adjustment ◽  
Relationship Of ◽  
Tendon Compliance

During downhill running, manoeuvring, negotiation of obstacles and landings from a jump, mechanical energy is dissipated via active lengthening of limb muscles. Tendon compliance provides a ‘shock-absorber’ mechanism that rapidly absorbs mechanical energy and releases it more slowly as the recoil of the tendon does work to stretch muscle fascicles. By lowering the rate of muscular energy dissipation, tendon compliance likely reduces the risk of muscle injury that can result from rapid and forceful muscle lengthening. Here, we examine how muscle–tendon mechanics are modulated in response to changes in demand for energy dissipation. We measured lateral gastrocnemius (LG) muscle activity, force and fascicle length, as well as leg joint kinematics and ground-reaction force, as turkeys performed drop-landings from three heights (0.5–1.5 m centre-of-mass elevation). Negative work by the LG muscle–tendon unit during landing increased with drop height, mainly owing to greater muscle recruitment and force as drop height increased. Although muscle strain did not increase with landing height, ankle flexion increased owing to increased tendon strain at higher muscle forces. Measurements of the length–tension relationship of the muscle indicated that the muscle reached peak force at shorter and likely safer operating lengths as drop height increased. Our results indicate that tendon compliance is important to the modulation of energy dissipation by active muscle with changes in demand and may provide a mechanism for rapid adjustment of function during deceleration tasks of unpredictable intensity.

Mechanical energy losses due to the movement of dislocations in molybdenum at high temperatures (0.3Tm)

2006 ◽  
Vol 353 (1-2) ◽  
pp. 127-134 ◽  
Author(s):  
G.I. Zelada-Lambri ◽  
O.A. Lambri ◽  
J.A. García
Keyword(s):  
High Temperatures ◽  
Mechanical Energy ◽  
Energy Losses
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