The Effects of Curved Foot Design Parameters on Planar Biped Walking

2012 ◽  
Author(s):  
Anne E. Martin ◽  
James P. Schmiedeler
Keyword(s):  
Knee Kinematics ◽  
Substantial Effect ◽  
Energetic Cost ◽  
Design Parameters ◽  
Energetic Efficiency ◽  
Bipedal Robots ◽  
Healthy Human ◽  
Circular Arc ◽  
Gait Kinematics ◽  
Hip Kinematics

Although the nature of their gaits is similar, planar bipeds with curved feet have been shown experimentally to be more energetically efficient than those with point feet. Further, both healthy human feet and prosthetic feet can be modeled as a circular arc with the center of curvature in front of the shank. Thus, understanding the effects of a curved foot’s properties on the energetic cost of gait and on gait kinematics has the potential to improve both bipedal robots and prosthesis design. To date, there has not been a systematic study of the effects of changing the foot radius and center of curvature location on symmetric bipeds. This paper explores the effects of changing the curved foot’s geometric properties for both two- and five-link planar, underactuated bipeds with instantaneous transfer of support at impact. It is found that the foot radius has a substantial effect on the energetic efficiency of a gait regardless of the morphology of the biped. The effect of foot center of curvature location on energy efficiency is dependent on the morphology of the biped and is much less significant than the effect of foot radius. Both the foot radius and center of curvature location affect the knee kinematics of the five-link biped. The foot radius affects the hip kinematics of the two-link biped.

Numerical Efforts of Aerodynamic Re-Design in a Single-Stage Transonic Axial Compressor: Part 1 — Stator Design

2017 ◽  
Author(s):  
Justin (Jongsik) Oh
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Axial Flow ◽  
Single Stage ◽  
Design Flow ◽  
Design Parameters ◽  
Original Design ◽  
Circular Arc ◽  
Surge Margin ◽  
Flow Compressor

In many aerodynamic design parameters for the axial-flow compressor, three variables of tailored blading, blade lean and sweep were considered in the re-design efforts of a transonic single stage which had been designed in 1960’s NASA public domains. As Part 1, the re-design was limited to the stator vane only. For the original MCA (Multiple Circular Arc) blading, which had been applied at all radii, the CDA (Controlled Diffusion Airfoil) blading was introduced at midspan as the first variant, and the endwalls of hub and casing (or tip) were replaced with the DCA (Double Circular Arc) blading for the second variant. Aerodynamic performance was predicted through a series of CFD analysis at design speed, and the best aerodynamic improvement, in terms of pressure ratio/efficiency and operability, was found in the first variant of tailored blading. It was selected as a baseline for the next design efforts with blade lean, sweep and both combined. Among 12 variants, a case of positively and mildly leaned blades was found the most attractive one, relative to the original design, providing benefits of an 1.0% increase of pressure ratio at design flow, an 1.7% increase of efficiency at design flow, a 10.5% increase of the surge margin and a 32.3% increase of the choke margin.

Study on the effects of tooth profile design parameters of rotor to performance of vacuum pump

2020 ◽  
Vol 34 (22n24) ◽  
pp. 2040141
Author(s):  
Van-The Tran ◽  
Bui Trung Thanh ◽  
Banh Tien Long ◽  
Hoang Quoc Tuan ◽  
Duc Toan Nguyen
Keyword(s):  
Vacuum Pump ◽  
Tooth Profile ◽  
Design Parameters ◽  
Tooth Root ◽  
Performance Indices ◽  
Circular Arc ◽  
Numerical Example ◽  
Design Flexibility ◽  
Profile Design ◽  
Rotor Tooth

The vacuum pump usually used traditional curves such as the circular, cycloidal curves and their combinations to construct tooth profile. However, to increase efficiency and design flexibility for the vacuum pump, a novel rotor tooth profile for Roots rotor of vacuum pumps is proposed. Which is named “CEIEC” tooth profile and orderly composed of five significant segments, a circular arc for tooth tip, an epicycloid curve with variable extension, an involute, an enveloped epicycloid curve and a conjugated circular arc for tooth root. A numerical example is presented to evaluate the performance indices for proposed vacuum pump, including the hermeticity coefficients of the rotor mesh gap and tip gap.

scholarly journals Gait Kinematics After Taping in Participants With Chronic Ankle Instability

2014 ◽  
Vol 49 (3) ◽  
pp. 322-330 ◽  
Author(s):  
Lisa Chinn ◽  
Jay Dicharry ◽  
Joseph M. Hart ◽  
Susan Saliba ◽  
Robert Wilder ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Gait Cycle ◽  
Sagittal Plane ◽  
Ankle Instability ◽  
Knee Kinematics ◽  
Chronic Ankle Instability ◽  
Mean Difference ◽  
Ankle Sprains ◽  
Lateral Ankle ◽  
Gait Kinematics

Context: Chronic ankle instability is characterized by repetitive lateral ankle sprains. Prophylactic ankle taping is a common intervention used to reduce the risk of ankle sprains. However, little research has been conducted to evaluate the effect ankle taping has on gait kinematics. Objective: To investigate the effect of taping on ankle and knee kinematics during walking and jogging in participants with chronic ankle instability. Design: Controlled laboratory study. Setting: Motion analysis laboratory. Patients or Participants: A total of 15 individuals (8 men, 7 women; age = 26.9 ± 6.8 years, height = 171.7 ± 6.3 cm, mass = 73.5 ± 10.7 kg) with self-reported chronic ankle instability volunteered. They had an average of 5.3 ± 3.1 incidences of ankle sprain. Intervention(s): Participants walked and jogged in shoes on a treadmill while untaped and taped. The tape technique was a traditional preventive taping procedure. Conditions were randomized. Main Outcome Measure(s): Frontal-plane and sagittal-plane ankle and sagittal-plane knee kinematics were recorded throughout the entire gait cycle. Group means and 90% confidence intervals were calculated, plotted, and inspected for percentages of the gait cycle in which the confidence intervals did not overlap. Results: During walking, participants were less plantar flexed from 64% to 69% of the gait cycle (mean difference = 5.73° ± 0.54°) and less inverted from 51% to 61% (mean difference = 4.34° ± 0.65°) and 76% to 81% (mean difference = 5.55° ± 0.54°) of the gait cycle when taped. During jogging, participants were less dorsiflexed from 12% to 21% (mean difference = 4.91° ± 0.18°) and less inverted from 47% to 58% (mean difference = 6.52° ± 0.12°) of the gait cycle when taped. No sagittal-plane knee kinematic differences were found. Conclusions: In those with chronic ankle instability, taping resulted in a more neutral ankle position during walking and jogging in shoes on a treadmill. This change in foot positioning and the mechanical properties of the tape may explain the protective aspect of taping in preventing lateral ankle sprains.

Reliability of Change-of-Direction Economy in Soccer Players

2020 ◽  
pp. 1-7 ◽  
Author(s):  
Filippo Dolci ◽  
Andrew E. Kilding ◽  
Tania Spiteri ◽  
Paola Chivers ◽  
Ben Piggott ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Minute Ventilation ◽  
Running Economy ◽  
Soccer Players ◽  
Energetic Cost ◽  
Energetic Efficiency ◽  
Oxygen Cost ◽  
Good Reliability ◽  
Change Of Direction ◽  
Physiological Variables

Purpose: To evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h−1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Results: Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%–5.8%; ICC = .77–.88), SRE10 (CV: 3.5%–3.8%; ICC = .78–.96), and SRE20 (CV: 3.5%–3.8%; ICC = .66–.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. Conclusion: The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players’ energetic movement efficiency under more soccer-specific running conditions.

Exergetic and Thermoeconomic Analysis of the “Villa de Reyes” Steam Power Plant Operating on Partial Load

2016 ◽  
Author(s):  
María D. Duran García ◽  
Juan A. Jiménez García ◽  
Bernd Weber
Keyword(s):  
Power Plant ◽  
Relation Extraction ◽  
Point Of View ◽  
Design Parameters ◽  
Energetic Efficiency ◽  
Steam Power ◽  
Total Load ◽  
Steam Power Plant ◽  
Partial Load ◽  
The Cost

In this paper a thermoeconomic and exergy analysis of a steam power plant located at Villa de Reyes, México is presented. This study is focused on the analysis on partial load of this plant. According to the steam power plant operation manual this plant is able to operate at 25%, 50%, 75% and 100% of the total load installed, and some design parameters are established for this operation loads. Nevertheless during this study it was observed that this parameters and operation loads conditions are not the most efficient from the energetic and exergetic point of view, and also, the values of the thermal parameters used for these operation loads were not the optimum. In this context the objective of this research was to design a model for the power plant simulation in order to determine the best design parameters and operation loads conditions for this particular facility. First of all the model was validated, with the information of the operation manual of the steam generator. Once the model was validated, it was achieved the thermal, exergetic and thermoeconomic analysis. As a result it was observed that the best operation load conditions are at 100%, 98.4%, 93.3% and 75.6%. Also some optimal values of air-gas relation, extraction pressure and drum pressure were found. It was observed that an energetic efficiency up to 35.5% and exergetic efficiency up to 29% may be achieved. Finally it was achieved the thermoeconomic analysis in order to determine the cost of the energetic and exergetic loses and identify the elements that produce the higher irreversibility.

Relationship between Bioenergetics and Behavior in Anadromous Fish Migrations

1987 ◽  
Vol 44 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Louis Bernatchez ◽  
Julian J. Dodson
Keyword(s):  
Energetic Cost ◽  
Energetic Efficiency ◽  
Migratory Behavior ◽  
Anadromous Fish ◽  
Upstream Migration ◽  
Energy Reserves ◽  
Unit Distance ◽  
Energy Expenditures ◽  
Migratory Strategy ◽  
And Behavior

Minimizing energetic cost per unit distance is often considered the major criterion that anadromous migrants seek to optimize during upstream migration. To test this theory, we documented energetic expenditures and travel speeds of 15 anadromous fish populations involving 9 species observed during their upstream migration. Parameters that characterized fish migratory behavior and the spawning river were calculated for each population. In most cases, cost per unit distance is not minimized and migratory strategy does not conform to the theoretical optimum. Populations that make long or difficult migrations are more efficient in their use of energy reserves than populations that make shorter migrations. Only populations that need all their energy to complete the migration swim at speeds that approach the theoretical optimum. Migration length may lead to improved migratory efficiency by selecting for larger body size, more accurate upstream orientation, and travel speeds that optimize energy efficiency. The failure to minimize energy expenditures is sometimes due to environmental constraints that exceed the physiological capacities of migrants. Minimizing the probablity of death due to exhaustion may be the major factor determining migratory behavior. Selection for energetic efficiency appears important only in cases where energy reserves are exhausted during migration.

scholarly journals The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs

2019 ◽  
Author(s):  
T. Alexander Dececchi ◽  
Aleksandra M. Mloszewska ◽  
Thomas R. Holtz ◽  
Michael B. Habib ◽  
Hans C.E. Larsson
Keyword(s):  
Body Size ◽  
Large Body ◽  
Limb Lengthening ◽  
Limb Length ◽  
Energetic Cost ◽  
Energetic Efficiency ◽  
Leg Length ◽  
Distal Limb ◽  
Cost Of Transport ◽  
The Impact

AbstractLimb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology as locomotory capacity, especially running ability, is critical in not just in prey pursuit but also to avoid become prey oneself. One aspect that is traditionally overlooked is the impact of allometry on running ability and the limiting effect of large body size. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ∼1000kg or more, the effect that such larger mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here using expansive datasets, incorporating several different metrics to estimate body size, limb length and running speed, to calculate the effects of allometry running We test both on traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length as well as comparing the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroids or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated, no commonly used metric including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length) shows a significant correlation to top speed. The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organisms’ size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods while no one strategy dictated hindlimb evolution. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole.

scholarly journals Dimensionless design approach to translating flat faced follower mechanism with two-circular-arc cam

2019 ◽  
Vol 10 (2) ◽  
pp. 497-503
Author(s):  
Emre Arabaci
Keyword(s):  
Rotation Angle ◽  
Maximum Velocity ◽  
Design Approach ◽  
Design Parameters ◽  
Circular Arc ◽  
Dimensionless Parameters ◽  
Absolute Acceleration ◽  
Cam Profile ◽  
Profile Design ◽  
Critical Characteristics

Abstract. In this study, a dimensionless design approach was presented for translating flat-faced follower mechanism with two-circular-arc cam. Instead of second arc radius (r2), maximum follower lift (smax) and angle of the cam rotation angle (2θmax) variables from the cam profile design parameters were made dimensionless using r2∕r (=λ), smax∕r (=ψ) and θmax∕π (=μ) respectively. Equations for cam profile and follower movement were derived and graphics were obtained depending on the dimensionless parameters. λ and ψ should be in the range [0.0, 1.0], but μ should be in the range [0.0, 0.5]. λ and ψ were changed in the range [0.10, 0.90] and μ in the [0.25, 0.45] range and λ, ψ and μ values were determined for the cam profile. Maximum velocity (vmax), maximum absolute acceleration (amax) and average follower lift (save) changes, which are one of the critical characteristics of follower, were examined for possible cam profiles according to the change of λ, ψ and μ. As a result, vmax and save decreased when μ was increased, vmax and save increased and amax decreased when ψ was increased, amax and save increased when λ was increased.

scholarly journals Orangutans use compliant branches to lower the energetic cost of locomotion

2007 ◽  
Vol 3 (3) ◽  
pp. 253-256 ◽  
Author(s):  
S.K.S Thorpe ◽  
R.H Crompton ◽  
R.McN Alexander
Keyword(s):  
Forest Canopy ◽  
Alternative Methods ◽  
Energetic Cost ◽  
Energetic Efficiency ◽  
Pongo Abelii ◽  
Cost Of Locomotion ◽  
Order Of Magnitude ◽  
Gap Crossing ◽  
Tree Sway ◽  
Phys Anthropol

Within the forest canopy, the shortest gaps between tree crowns lie between slender terminal branches. While the compliance of these supports has previously been shown to increase the energetic cost of gap crossing in arboreal animals (e.g. Alexander 1991 Z. Morphol. Anthropol. 78 , 315–320; Demes et al . 1995 Am. J. Phys. Anthropol. 96 , 419–429), field observations suggest that some primates may be able to use support compliance to increase the energetic efficiency of locomotion. Here, we calculate the energetic cost of alternative methods of gap crossing in orangutans ( Pongo abelii ). Tree sway (in which orangutans oscillate a compliant tree trunk with increasing magnitude to bridge a gap) was found to be less than half as costly as jumping, and an order of magnitude less costly than descending the tree, walking to the vine and climbing it. Observations of wild orangutans suggest that they actually use support compliance in many aspects of their locomotor behaviour. This study seems to be the first to show that elastic compliance in arboreal supports can be used to reduce the energetic cost of gap crossing.

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