Using body size to understand the structural design of animals: quadrupedal locomotion

1975 ◽  
Vol 39 (4) ◽  
pp. 619-627 ◽  
Author(s):  
T. A. McMahon
Keyword(s):  
Stride Length ◽  
Small Body ◽  
Resting Metabolic Rate ◽  
Theoretical Models ◽  
Stride Frequency ◽  
Maximum Speed ◽  
Published Data ◽  
Body Weights ◽  
And Performance ◽  
Sprinting Speed

Many parameters of gait and performance, including stride frequency, stride length, maximum speed, and rate of O2 uptake are experimentally found to be power-law functions of body weight in running quadrupeds. All of these parameters are reasonably easy to measure except maximum speed, where the question arises whether one means top sprinting speed or top speed for sustained running. Moreover, differences in training and motivation make comparisons of top speed difficult. The problem is circumvented by comparing animals running at the transition between trotting and galloping, a physiologically similar speed. Theoretical models are proposed which preserve either geometric similarity, elastic similarity, or static stress similarity between animals of large and small body weights. The model postulating elastic similarity provides the best correlation with published data on body and bone proportions, body surface area, resting metabolic rate, and basal heart and lung frequencies. It also makes the most successful prediction of stride frequency, stride length, limb excursion angles, and the metabolic power required for running at the trot-gallop transition in quadrupeds ranging in size from mice to horses.

scholarly journals Phylogenetic and Ontogenetic determinants of sprint performance in some diurnal Kalahari Lizards

Koedoe ◽  
1982 ◽  
Vol 25 (1) ◽  
Author(s):  
R. B Huey
Keyword(s):  
Stride Length ◽  
Sprint Performance ◽  
Stride Frequency ◽  
Maximum Speed ◽  
Body Proportions ◽  
Body Sizes

Sprint capacities (maximum speed, acceleration, stride length, stride frequency) of diurnal lizards from the Kalahari were measured on sandy substrates in the laboratory. Despite major interfamilial differences in body sizes and in body proportions, measures of sprint capacity were remarkably similar among families: some heavy bodied skinks ran as fast as did some sleek lacertids. Sprint capacities change during ontogeny in lizards. Maximum speed, stride length, and possibly acceleration all increase with size and presumably with age.

Surgical Drilling: Design and Performance of an Improved Drill

1982 ◽  
Vol 104 (3) ◽  
pp. 245-252 ◽  
Author(s):  
S. Saha ◽  
S. Pal ◽  
J. A. Albright
Keyword(s):  
Compact Bone ◽  
Helix Angle ◽  
Rake Angle ◽  
Peak Temperature ◽  
Published Data ◽  
Drill Bit ◽  
Effective Removal ◽  
Split Point ◽  
And Performance ◽  
Twist Drills

The majority of twist drills used in orthopaedics are very similar to chisel pointed metal drilling bits. Modifications usually observed are reduction of the point angle to 90 deg and sometimes grinding of the entire cutting lip at 0 deg rake angle, which appeared to have been made arbitrarily without any advantage. We have attempted to design a surgical drill bit with the objective of minimization of the drilling thrust and temperature and effective removal of bone chips. Our results showed that the presence of the chisel edge was mainly responsible for increasing the thrust force and the temperature developed. The effects of a constant feed rate and thrust on the peak temperature were also examined. The combined effect of the helix and the point angles on the rake angle which in turn determines the cutting efficiency was analyzed for various types of surgical bits. Based on our results and previously published data from the literature an optimized drill bit was designed with a split point, a point angle of 118 deg, a parabolic flute, and a helix angle of 36 deg and its performance was compared with other existing surgical drill bits. For drilling in compact bone, the new design decreased the thrust load by 45 percent and the peak temperature rise by 41 percent. Simlar improvements were also recorded for drilling bone cement. The time of drilling a bone cortex was also significantly reduced and “walking” on the curved bone surface was eliminated and dimensional tolerance on hole sizes was improved. The new design is likely to reduce the time of surgery and also minimize the tissue damage.

Dynamics and Performance of a Harmonically Excited Vertical Impact Damper

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Sanjiv Ramachandran ◽  
George Lesieutre
Keyword(s):  
Loss Factor ◽  
Vertical Direction ◽  
Theoretical Models ◽  
Coefficient Of Restitution ◽  
Numerical Continuation ◽  
Particle Impact ◽  
Impact Damper ◽  
High Loss ◽  
Wide Range ◽  
And Performance

Particle impact dampers (PIDs) have been shown to be effective in vibration damping. However, our understanding of such dampers is still limited, based on the theoretical models existing today. Predicting the performance of the PID is an important problem, which needs to be investigated more thoroughly. This research seeks to understand the dynamics of a PID as well as those parameters which govern its behavior. The system investigated is a particle impact damper with a ceiling, under the influence of gravity. The base is harmonically excited in the vertical direction. A two-dimensional discrete map is obtained, wherein the variables at one impact uniquely dictate the variables at the next impact. This map is solved using a numerical continuation procedure. Periodic impact motions and “irregular” motions are observed. The effects of various parameters such as the gap clearance, coefficient of restitution, and the base acceleration are analyzed. The dependence of the effective damping loss factor on these parameters is also studied. The loss factor results indicate peak damping for certain combinations of parameters. These combinations of parameters correspond to a region in parameter space where two-impacts-per-cycle motions are observed over a wide range of nondimensional base accelerations. The value of the nondimensional acceleration at which the onset of two-impacts-per-cycle solutions occurs depends on the nondimensional gap clearance and the coefficient of restitution. The range of nondimensional gap clearances over which two-impacts-per-cycle solutions are observed increases as the coefficient of restitution increases. In the regime of two-impacts-per-cycle solutions, the value of nondimensional base acceleration corresponding to onset of these solutions initially decreases and then increases with increasing nondimensional gap clearance. As the two-impacts-per-cycle solutions are associated with high loss factors that are relatively insensitive to changing conditions, they are of great interest to the designer.

A virtual test environment for validating spacecraft optical navigation

2013 ◽  
Vol 117 (1197) ◽  
pp. 1075-1101 ◽  
Author(s):  
S. M. Parkes ◽  
I. Martin ◽  
M. N. Dunstan ◽  
N. Rowell ◽  
O. Dubois-Matra ◽  
...  
Keyword(s):  
Small Body ◽  
European Space Agency ◽  
Ground Truth ◽  
Camera Motion ◽  
Test Environment ◽  
Space Applications ◽  
Vision Guidance ◽  
Space Agency ◽  
Wide Range ◽  
And Performance

Abstract The use of machine vision to guide robotic spacecraft is being considered for a wide range of missions, such as planetary approach and landing, asteroid and small body sampling operations and in-orbit rendezvous and docking. Numerical simulation plays an essential role in the development and testing of such systems, which in the context of vision-guidance means that realistic sequences of navigation images are required, together with knowledge of the ground-truth camera motion. Computer generated imagery (CGI) offers a variety of benefits over real images, such as availability, cost, flexibility and knowledge of the ground truth camera motion to high precision. However, standard CGI methods developed for terrestrial applications lack the realism, fidelity and performance required for engineering simulations. In this paper, we present the results of our ongoing work to develop a suitable CGI-based test environment for spacecraft vision guidance systems. We focus on the various issues involved with image simulation, including the selection of standard CGI techniques and the adaptations required for use in space applications. We also describe our approach to integration with high-fidelity end-to-end mission simulators, and summarise a variety of European Space Agency research and development projects that used our test environment.

Speed, stride frequency and energy cost per stride: how do they change with body size and gait?

1988 ◽  
Vol 138 (1) ◽  
pp. 301-318 ◽  
Author(s):  
N. C. Heglund ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Energy Cost ◽  
Reaction Force ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Published Data ◽  
Frequency Change ◽  
Cost Of Locomotion ◽  
The Cost

In this study we investigate how speed and stride frequency change with body size. We use this information to define ‘equivalent speeds’ for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a gallop all change in the same rather dramatic manner with body size, differing by nine-fold between mice and horses (i.e. all three speeds scale with about the 0.2 power of body mass). Although the absolute speeds differ greatly, the maximum sustainable speed was about 2.6-fold greater than the minimum within a trot, and 2.1-fold greater within a gallop. The frequencies used to sustain the equivalent speeds (with the exception of the minimum trotting speed) scale with about the same factor, the −0.15 power of body mass. Combining this speed and frequency data with previously published data on the energetic cost of locomotion, we find that the mass-specific energetic cost of locomotion is almost directly proportional to the stride frequency used to sustain a constant speed at all the equivalent speeds within a trot and a gallop, except for the minimum trotting speed (where it changes by a factor of two over the size range of animals studied). Thus the energy cost per kilogram per stride at five of the six equivalent speeds is about the same for all animals, independent of body size, but increases with speed: 5.0 J kg-1 stride-1 at the preferred trotting speed; 5.3 J kg-1 stride-1 at the trot-gallop transition speed; 7.5 J kg-1 stride-1 at the preferred galloping speed; and 9.4 J kg-1 stride-1 at the maximum sustained galloping speed. The cost of locomotion is determined primarily by the cost of activating muscles and of generating a unit of force for a unit of time. Our data show that both these costs increase directly with the stride frequency used at equivalent speeds by different-sized animals. The increase in cost per stride with muscles (necessitating higher muscle forces for the same ground reaction force) as stride length increases both in the trot and in the gallop.

scholarly journals Functional Electrical Stimulation Changes Dynamic Resources in Children With Spastic Cerebral Palsy

2006 ◽  
Vol 86 (7) ◽  
pp. 987-1000 ◽  
Author(s):  
Chia-Ling Ho ◽  
Kenneth G Holt ◽  
Elliot Saltzman ◽  
Robert C Wagenaar
Keyword(s):  
Cerebral Palsy ◽  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Stride Length ◽  
The Body ◽  
Stride Frequency ◽  
Spastic Cerebral Palsy ◽  
Significant Difference ◽  
Muscle Complex ◽  
Spring System

Abstract Background and Purpose. Children with cerebral palsy (CP) often are faced with difficulty in walking. The purpose of this experiment was to determine the effects of functional electrical stimulation (FES) applied to the gastrocnemius-soleus muscle complex on the ability to produce appropriately timed force and reduce stiffness (elastic property of the body) and on stride length and stride frequency during walking. Subjects and Methods. Thirteen children with spastic CP (including 4 children who were dropped from the study due to their inability to cooperate) and 6 children who were developing typically participated in the study. A crossover study design was implemented. The children with spastic CP were randomly assigned to either a group that received FES for 15 trials followed by no FES for 15 trials or a group that received no FES for 15 trials followed by FES for 15 trials. The children who were having typical development walked without FES. Kinematic data were collected for the children with CP in each walking condition and for the children who were developing typically. Impulse (force-producing ability) and stiffness were estimated from an escapement-driven pendulum and spring system model of human walking. Stride length and stride frequency also were measured. To compare between walking conditions and between the children with CP and the children who were developing typically, dimensional analysis and speed normalization procedures were used. Results. Nonparametric statistics showed that there was no significant difference between the children with CP in the no-FES condition and the children who were developing typically on speed-normalized dimensionless impulse. In contrast, the children with CP in the FES condition had a significantly higher median value than the children who were developing typically. The FES significantly increased speed-normalized dimensionless impulse from 10.02 to 16.32 when comparing walking conditions for the children with CP. No significant differences were found between walking conditions for stiffness, stride length, and stride frequency. Discussion and Conclusion. The results suggest that FES is effective in increasing impulse during walking but not in decreasing stiffness. The effect on increasing impulse does not result in more typical spatiotemporal gait parameters. [Ho CL, Holt KG, Saltzman E, Wagenaar RC. Functional electrical stimulation changes dynamic resources in children with spastic cerebral palsy. Phys Ther. 2006;86:987–1000.]

scholarly journals An Empirical Study of S-commerce Adoption on WeChat Platform

2020 ◽  
Vol 5 (3) ◽  
pp. 80
Author(s):  
Mei Ge ◽  
Zhongping Deng ◽  
Jing He
Keyword(s):  
Empirical Study ◽  
Behavioral Intention ◽  
Online Survey ◽  
Theoretical Models ◽  
Utaut Model ◽  
Performance Expectancy ◽  
Proposed Model ◽  
Effort Expectancy ◽  
Pls Analysis ◽  
And Performance

<p>The purpose of this paper is empirically to examine two theoretical models in the context of social electronic commerce (s-commerce). The study tries to extend TAM and UTAUT model with trust to explain consumer behavior in the acceptance of s-commerce on WeChat platform which is the Chinese largest social platform. Through an online survey, 501 valid respondents were collected. A Partial Least Squares (PLS) analysis was used to conduct the proposed model and hypothesis testing with TAM and UTAUT models. The results revealed that trust is the most significant factor affecting behavioral intention and the second significant factor is effort expectancy, then social influence and performance expectancy. The integration of trust factor into the UTAUT model best interprets the adoption of s-commerce among the pure TAM and UTAUT models and extended models with trust. It will provide guidance for marketers and professionals, especially in China.</p>

scholarly journals Supervised Exercise Training Improves 6 min Walking Distance and Modifies Gait Pattern during Pain-Free Walking Condition in Patients with Symptomatic Lower Extremity Peripheral Artery Disease

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7989
Author(s):  
Stefano Lanzi ◽  
Joël Boichat ◽  
Luca Calanca ◽  
Lucia Mazzolai ◽  
Davide Malatesta
Keyword(s):  
Stride Length ◽  
Gait Pattern ◽  
Walking Distance ◽  
Stride Frequency ◽  
Walk Test ◽  
Relative Duration ◽  
Foot Kinematics ◽  
Supervised Exercise ◽  
Artery Disease ◽  
Kinematics Parameters

This study aimed to investigate the effects of supervised exercise training (SET) on spatiotemporal gait and foot kinematics parameters in patients with symptomatic lower extremity peripheral artery disease (PAD) during a 6 min walk test. Symptomatic patients with chronic PAD (Fontaine stage II) following a 3 month SET program were included. Prior to and following SET, a 6 min walk test was performed to assess the 6 min walking distance (6MWD) of each patient. During this test, spatiotemporal gait and foot kinematics parameters were assessed during pain-free and painful walking conditions. Twenty-nine patients with PAD (65.4 ± 9.9 years.) were included. The 6MWD was significantly increased following SET (+10%; p ≤ 0.001). The walking speed (+8%) and stride frequency (+5%) were significantly increased after SET (p ≤ 0.026). The stride length was only significantly increased during the pain-free walking condition (+4%, p = 0.001), whereas no significant differences were observed during the condition of painful walking. Similarly, following SET, the relative duration of the loading response increased (+12%), the relative duration of the foot-flat phase decreased (−3%), and the toe-off pitch angle significantly increased (+3%) during the pain-free walking condition alone (p ≤ 0.05). A significant positive correlation was found between changes in the stride length (r = 0.497, p = 0.007) and stride frequency (r = 0.786, p ≤ 0.001) during pain-free walking condition and changes in the 6MWD. A significant negative correlation was found between changes in the foot-flat phase during pain-free walking condition and changes in the 6MWD (r = −0.567, p = 0.002). SET was found to modify the gait pattern of patients with symptomatic PAD, and many of these changes were found to occur during pain-free walking. The improvement in individuals’ functional 6 min walk test was related to changes in their gait pattern.

scholarly journals Low turbidity in recirculating aquaculture systems (RAS) reduces feeding behaviour and increases stress-related physiological parameters in pikeperch (Sander lucioperca) during grow-out

2021 ◽  
Author(s):  
Stephan S W Ende ◽  
Ekaterina Larceva ◽  
Mirko Bögner ◽  
Vincent Lugert ◽  
Matthew James Slater ◽  
...  
Keyword(s):  
Feed Intake ◽  
Economic Consequences ◽  
Feeding Time ◽  
Sander Lucioperca ◽  
Recirculating Aquaculture ◽  
Recirculating Aquaculture Systems ◽  
Body Weights ◽  
High Turbidity ◽  
And Performance ◽  
Species Specific

Abstract There is a tendency to farm fish in low turbidity water when production takes place in the land-based recirculating aquaculture systems (RAS). However, the effect of water turbidity on stress and performance is unknown for many species cultured in RAS. The effect of different turbidity treatments as Formazine Attenuation Units (0 FAU, 15 FAU, and 38 FAU) on feed intake performance (latency, total feeding time, and total feed intake) and physiological blood stress parameters (cortisol, lactate, and glucose) in medium-sized pikeperch ((Sander lucioperca) n = 27, undetermined sex and age) of initial body weights of 508.13g ± 83 g (at FAU 0, 15 and 38, respectively) was investigated. The rearing system consisted of 9 rectangular tanks (200 L per tank). Fish were housed individually (n = 1, per tank, n replicates per treatment = 9). All tanks were connected to a recirculation system equipped with a moving bed biofilter. Feed intake in pikeperch kept at low turbidity (0 FAU) was 25% lower than pikeperch kept at high turbidity (38 FAU) (P&lt;0.01) and also significantly (10.5%) lower compared to feed intake in pikeperch kept at intermediate turbidity (15 FAU) (P&lt;0.01 for 0 FAU vs 15 FAU, feed intake sign. Value as the main effect is P&lt;0.01). Pikeperch kept at low turbidity showed significantly slower feeding response (latency time) towards pellets entering the tank, shorter feeding times (both P&lt; 0.05), and higher glucose blood concentration (73%) in contrast to pikeperch kept at highest turbidity. A reduction of 25% feed intake has obvious economic consequences for any fish farm and present data strongly emphasize the importance of considering the species-specific biology in future RAS farming.

MobiDB-lite 3.0: fast consensus annotation of intrinsic disorder flavors in proteins

2020 ◽  
Author(s):  
Marco Necci ◽  
Damiano Piovesan ◽  
Damiano Clementel ◽  
Zsuzsanna Dosztányi ◽  
Silvio C E Tosatto
Keyword(s):  
Large Scale ◽  
Theoretical Models ◽  
Intrinsic Disorder ◽  
Low Complexity ◽  
Compositional Bias ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Proteome Level ◽  
And Performance

Abstract Motivation The earlier version of MobiDB-lite is currently used in large-scale proteome annotation platforms to detect intrinsic disorder. However, new theoretical models allow for the classification of intrinsically disordered regions into subtypes from sequence features associated with specific polymeric properties or compositional bias. Results MobiDB-lite 3.0 maintains its previous speed and performance but also provides a finer classification of disorder by identifying regions with characteristics of polyolyampholytes, positive or negative polyelectrolytes, low-complexity regions or enriched in cysteine, proline or glycine or polar residues. Subregions are abundantly detected in IDRs of the human proteome. The new version of MobiDB-lite represents a new step for the proteome level analysis of protein disorder. Availability and implementation Both the MobiDB-lite 3.0 source code and a docker container are available from the GitHub repository:https://github.com/BioComputingUP/MobiDB-lite

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