scholarly journals Cockroaches traverse crevices, crawl rapidly in confined spaces, and inspire a soft, legged robot

2016 ◽  
Vol 113 (8) ◽  
pp. E950-E957 ◽  
Author(s):  
Kaushik Jayaram ◽  
Robert J. Full
Keyword(s):  
Body Weight ◽  
High Speed ◽  
Stride Length ◽  
Body Height ◽  
Legged Robot ◽  
Confined Space ◽  
Performance Limits ◽  
Biological Inspiration ◽  
Confined Spaces ◽  
Postural Changes

Jointed exoskeletons permit rapid appendage-driven locomotion but retain the soft-bodied, shape-changing ability to explore confined environments. We challenged cockroaches with horizontal crevices smaller than a quarter of their standing body height. Cockroaches rapidly traversed crevices in 300–800 ms by compressing their body 40–60%. High-speed videography revealed crevice negotiation to be a complex, discontinuous maneuver. After traversing horizontal crevices to enter a vertically confined space, cockroaches crawled at velocities approaching 60 cm⋅s−1, despite body compression and postural changes. Running velocity, stride length, and stride period only decreased at the smallest crevice height (4 mm), whereas slipping and the probability of zigzag paths increased. To explain confined-space running performance limits, we altered ceiling and ground friction. Increased ceiling friction decreased velocity by decreasing stride length and increasing slipping. Increased ground friction resulted in velocity and stride length attaining a maximum at intermediate friction levels. These data support a model of an unexplored mode of locomotion—“body-friction legged crawling” with body drag, friction-dominated leg thrust, but no media flow as in air, water, or sand. To define the limits of body compression in confined spaces, we conducted dynamic compressive cycle tests on living animals. Exoskeletal strength allowed cockroaches to withstand forces 300 times body weight when traversing the smallest crevices and up to nearly 900 times body weight without injury. Cockroach exoskeletons provided biological inspiration for the manufacture of an origami-style, soft, legged robot that can locomote rapidly in both open and confined spaces.

Fault Tolerant Gaits for a Six-Legged Robot With One Locked or Uncontrollable Failure

2014 ◽  
Author(s):  
Hui Du ◽  
Feng Gao ◽  
Yang Pan
Keyword(s):  
High Speed ◽  
Stride Length ◽  
Fault Tolerant ◽  
Legged Robots ◽  
Robot Kinematics ◽  
Legged Robot ◽  
Long Distance ◽  
Gait Study

Multi-legged robots need fault tolerant gaits if one or more legs are broken down and cannot have maintenance when in long-distance operations or hash environments. There are two common faults of robot actuations: locked and uncontrollable failure. In this paper, a novel parallel-parallel six-legged robot as our prototype has good fault tolerant capability to continue walking with a locked or uncontrollable leg. The leg sequence and the formula of the leg/body stride length are driven based on gait study and robot kinematics. Then, a continuous fault tolerant gait is proposed which enables the robot maintain high speed and stability.

scholarly journals Exploratory Investigation of Impact Loads During the Forward Handspring Vault

2015 ◽  
Vol 46 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Gabriella Penitente ◽  
William A. Sands
Keyword(s):  
Body Weight ◽  
High Intensity ◽  
High Speed ◽  
Body Height ◽  
Video Camera ◽  
Peak Force ◽  
Impact Loads ◽  
Time To Peak ◽  
High Speed Video Camera ◽  
Force Time

AbstractThe purpose of this study was to examine kinematic and kinetic differences in low and high intensity hand support impact loads during a forward handspring vault. A high-speed video camera (500 Hz) and two portable force platforms (500 Hz) were installed on the surface of the vault table. Two-dimensional analyses were conducted on 24 forward handspring vaults performed by 12 senior level, junior Olympic program female gymnasts (16.9 ±1.4 yr; body height 1.60 ±0.1 m; body mass 56.7 ±7.8 kg). Load intensities at impact with the vault table were classified as low (peak force < 0.8 × body weight) and high (peak force > 0.8 × body weight). These vaults were compared via crucial kinetic and kinematic variables using independent t-tests and Pearson correlations. Statistically significant (p < 0.001) differences were observed in peak force (t(24) = 4.75, ES = 3.37) and time to peak force (t(24) = 2.07, ES = 1.56). Statistically significant relationships between the loading rate and time to peak force were observed for high intensity loads. Peak force, time to peak force, and a shoulder angle at impact were identified as primary variables potentially involved in the determination of large repetitive loading rates on the forward handspring vault.

scholarly journals Growth and development of children under 5 years of age with tetralogy of Fallot in a Chinese population

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Li ◽  
Jin Zhu ◽  
Jun An ◽  
Yuqing Wang ◽  
Yili Wu ◽  
...  
Keyword(s):  
Body Weight ◽  
Tetralogy Of Fallot ◽  
Growth Retardation ◽  
Growth And Development ◽  
Heart Defects ◽  
Body Height ◽  
Child Growth ◽  
The Body ◽  
Early Age ◽  
Local Conditions

AbstractCongenital Heart Defects (CHDs) are associated with different patterns of malnutrition and growth retardation, which may vary worldwide and need to be evaluated according to local conditions. Although tetralogy of Fallot (TOF) is one of the first described CHDs, the etiology outcomes in growth and development of TOF in early age child is still unclear in most cases. This study was designed to investigate the growth retardation status of Chinese pediatric TOF patients under 5 years old. The body height, body weight and body mass index (BMI) of 262 pediatric patients (138 boys and 124 girls) who underwent corrective surgery for TOF between 2014 and 2018 were measured using conventional methods. The average body height, body weight and BMI of the patients were significantly lower than WHO Child Growth Standards, while the most affected was body height. Meanwhile, higher stunting frequency and greater deterioration of both the body height and weight happened in elder age (aged 13–60 months) rather than in infant stage (aged 0–12 months) among these patients. Our results confirmed that intervention should be given at early age to prevent the growth retardation of TOF patients getting severer.

scholarly journals Detection of 15-bp Deletion Mutation within PLAG1 Gene and Its Effects on Growth Traits in Goats

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2064
Author(s):  
Zhenyu Wei ◽  
Ke Wang ◽  
Hui Wu ◽  
Zhen Wang ◽  
Chuanying Pan ◽  
...  
Keyword(s):  
Body Weight ◽  
Growth Traits ◽  
Body Height ◽  
The Body ◽  
Chest Circumference ◽  
Dairy Goat ◽  
Cashmere Goat ◽  
Indel Mutation ◽  
Body Stature ◽  
Body Index

Stature and weight are important growth and development traits for animals, which also significantly affect the productivity of livestock. Polymorphic adenoma gene 1 (PLAG1) is located in the growth-related quantitative trait nucleotides (QTN), and its variation has been determined to significantly affect the body stature of bovines. This study found that novel 15-bp InDel could significantly influence important growth traits in goats. The frequencies of genotypes of the 15-bp mutation and relationship with core growth traits such as body weight, body height, height at hip cross, chest circumference, hip width and body index were explored in 1581 individuals among 4 Chinese native goat breeds. The most frequent genotypes of Shaanbei white Cashmere goat (SWCG), Inner Mongolia White Cashmere goat (IMCG) and Guanzhong Dairy goat (GZDG) were II genotypes (insertion/insertion), and the frequency of ID genotype (insertion/deletion) was found to be slightly higher than that of II genotype in Hainan Black goat (HNBG), showing that the frequency of the I allele was higher than that of the D allele. In adult goats, there were significant differences between 15-bp variation and body weight, chest circumference and body height traits in SWCG (p < 0.05). Furthermore, the locus was also found to be significantly correlated with the body index of HNBG (p = 0.044) and hip width in GZDG (p = 0.002). In regard to lambs, there were significant differences in height at the hip cross of SWCG (p = 0.036) and hip width in IMWC (p = 0.005). The corresponding results suggest that the 15-bp InDel mutation of PLAG1 is associated with the regulation of important growth characteristics of both adult and lamb of goats, which may serve as efficient molecular markers for goat breeding.

scholarly journals Systematic Performance Comparison of (Duobinary)-PAM-2,4 Signaling under Light and Strong Opto-Electronic Bandwidth Conditions

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 81
Author(s):  
Ramón Gutiérrez-Castrejón ◽  
Md Ghulam Saber ◽  
Md Samiul Alam ◽  
Zhenping Xing ◽  
Eslam El-Fiky ◽  
...  
Keyword(s):  
Optical Networks ◽  
High Speed ◽  
Performance Comparison ◽  
Sampling Point ◽  
Bit Rate ◽  
Performance Limits ◽  
Specific System ◽  
Rate System ◽  
Modulation Formats ◽  
Modulation Format

We present a systematic comparison of PAM-2 (NRZ), Duobinary-PAM-2, PAM-4, and Duobinary-PAM-4 (duo-quaternary) signaling in the context of short-reach photonic communications systems using a Mach–Zehnder modulator as transmitter. The effect on system performance with a relaxed and constrained system’s opto-electronic bandwidth is analyzed for bit rates ranging from 20 to 116 Gb/s. In contrast to previous analyses, our approach employs the same experimental and simulation conditions for all modulation formats. Consequently, we were able to confidently determine the performance limits of each format for particular values of bit rate, system bandwidth, transmitter chirp, and fiber dispersion. We demonstrate that Duobinary-PAM-4 is a good signaling choice only for bandwidth-limited systems operating at relatively high speed. Otherwise, PAM-4 represents a more sensible choice. Moreover, our analysis put forward the existence of transition points: specific bit rate values where the BER versus bit rate curves for two different formats cross each other. They indicate the bit rate values where, for specific system conditions, switching from one modulation to another guarantees optimum performance. Their existence naturally led to the proposal of a format-selective transceiver, a component that, according to network conditions, operates with the most adequate modulation format. Since all analyzed modulations share similar implementation details, signaling switching is achieved by simply changing the sampling point and threshold count at the receiver, bringing flexibility to IM/DD-based optical networks.

scholarly journals Optimal nonlinear eddy viscosity in Galerkin models of turbulent flows

2015 ◽  
Vol 766 ◽  
pp. 337-367 ◽  
Author(s):  
Bartosz Protas ◽  
Bernd R. Noack ◽  
Jan Östh
Keyword(s):  
Turbulent Flows ◽  
High Speed ◽  
Eddy Viscosity ◽  
Broad Class ◽  
Constitutive Relations ◽  
Body Height ◽  
Mixing Layer ◽  
The Body ◽  
Stream Velocity ◽  
Initial Vorticity

AbstractWe propose a variational approach to the identification of an optimal nonlinear eddy viscosity as a subscale turbulence representation for proper orthogonal decomposition (POD) models. The ansatz for the eddy viscosity is given in terms of an arbitrary function of the resolved fluctuation energy. This function is found as a minimizer of a cost functional measuring the difference between the target data coming from a resolved direct or large-eddy simulation of the flow and its reconstruction based on the POD model. The optimization is performed with a data-assimilation approach generalizing the 4D-VAR method. POD models with optimal eddy viscosities are presented for a 2D incompressible mixing layer at $\mathit{Re}=500$ (based on the initial vorticity thickness and the velocity of the high-speed stream) and a 3D Ahmed body wake at $\mathit{Re}=300\,000$ (based on the body height and the free-stream velocity). The variational optimization formulation elucidates a number of interesting physical insights concerning the eddy-viscosity ansatz used. The 20-dimensional model of the mixing-layer reveals a negative eddy-viscosity regime at low fluctuation levels which improves the transient times towards the attractor. The 100-dimensional wake model yields more accurate energy distributions as compared to the nonlinear modal eddy-viscosity benchmark proposed recently by Östh et al. (J. Fluid Mech., vol. 747, 2014, pp. 518–544). Our methodology can be applied to construct quite arbitrary closure relations and, more generally, constitutive relations optimizing statistical properties of a broad class of reduced-order models.

Relationship between axial length of the emmetropic eye and the age, body height, and body weight of schoolchildren

2005 ◽  
Vol 17 (2) ◽  
pp. 173-177 ◽  
Author(s):  
Alen ?elovi? ◽  
Vesna Juresa ◽  
Davor Ivankovic ◽  
Davor Malcic ◽  
Gordana ?elovi? Bobonj
Keyword(s):  
Body Weight ◽  
Axial Length ◽  
Body Height

scholarly journals „Z”-scores of anthropometric and motor parameters of girls in aerobic gymnastics

2014 ◽  
Vol 61 (2) ◽  
pp. 55-58
Author(s):  
M. Tibenská ◽  
H. Medeková
Keyword(s):  
Body Weight ◽  
Body Height ◽  
Sport Performance ◽  
Z Score ◽  
Anthropometric Parameters ◽  
Percentage Of Body Fat ◽  
Standing Long Jump ◽  
Z Scores ◽  
Long Jump ◽  
Shuttle Run

Abstract This study presents the evaluation of chosen anthropometric and motor parameters in group of female junior competitors throughout the course of 2-year preparation of aerobic gymnastics by means of Z-scores. The observed group consisted of 12 girls (average age at the beginning of observance 14.08 ± 1.19 years). Evaluation of anthropometric (body height, body weight, body mass index, percentage of body fat, acting body weight) and motor parameters (sit-ups in 30 seconds and 60 seconds, pull-ups to bar, modified push-ups, standing long jump, backwards tandem walking, shuttle run 4×10 m, Jacík’s test) was carried out in standard conditions in nine girls at 3-month intervals. It has been confirmed that female probands with higher Z-score of motor parameters together with lower Z-score of anthropometric parameters achieved higher sport performance during the 2-year observance at competitions, with an exception of one such proband.

scholarly journals The Accuracy of Broselow Tape Weight Estimate among Pediatric Population

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Turki M. AlHarbi ◽  
Abdullaziz AlGarni ◽  
Fasial AlGamdi ◽  
Mona Jawish ◽  
Tariq Ahmad Wani ◽  
...  
Keyword(s):  
Body Weight ◽  
Pediatric Population ◽  
Body Height ◽  
Age Groups ◽  
Cross Sectional Study ◽  
The Body ◽  
Accurate Estimation ◽  
Cross Sectional ◽  
Actual Weight ◽  
Medical City

Objective.To determine the accuracy of the Broselow Tape (BT) versions 2007 and 2011 in estimating weight among pediatric population.Methods.A cross-sectional study was conducted at King Fahad Medical City and six schools across Riyadh province on 1–143-month-old children. BT 2007 and 2011 estimated weights were recorded. Both tapes via the child’s height produce an estimated weight, which was compared with the actual weight.Results.A total of 3537 children were recruited. The height (cm) of the subjects was97.7±24.1and the actual weight (kg) was16.07±8.9, whereas the estimated weight determined by BT 2007 was15.87±7.56and by BT 2011 was16.38±7.95. Across all the five age groups, correlation between actual weight and BT 2007 ranged between 0.702 and 0.788, while correlation between actual weight and BT 2011 ranged between 0.698 and 0.788. Correlation between BT 2007 and BT 2011 across all the five age groups ranged from 0.979 to 0.989. Accuracy of both the tape versions was adversely affected when age was >95 months and body weight was >26 kilograms.Conclusions.Our study showed that BT 2007 and 2011 provided accurate estimation of the body weight based on measured body height. However, 2011 version provided more precise estimate for weight.

Sign in / Sign up

Export Citation Format

Share Document