Mechanisms of helical swimming: asymmetries in the morphology, movement and mechanics of larvae of the ascidian Distaplia occidentalis

2001 ◽  
Vol 204 (17) ◽  
pp. 2959-2973 ◽  
Author(s):  
Matthew J. McHenry
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
The Body ◽  
Hydrodynamic Theory ◽  
Helical Motion ◽  
Body Rotation ◽  
Oblique Angle ◽  
Free Swimming ◽  
Three Point Bending ◽  
And Control

SUMMARY A great diversity of unicellular and invertebrate organisms swim along a helical path, but it is not well understood how asymmetries in the body shape or the movement of propulsive structures affect a swimmer’s ability to perform the body rotation necessary to move helically. The present study found no significant asymmetries in the body shape of ascidian larvae (Distaplia occidentalis) that could operate to rotate the body during swimming. By recording the three-dimensional movement of free-swimming larvae, it was found that the tail possessed two bends, each with constant curvature along their length. As these bends traveled posteriorly, the amplitude of curvature changes was significantly greater in the concave-left direction than in the concave-right direction. In addition to this asymmetry, the tail oscillated at an oblique angle to the midline of the trunk. These asymmetries generated a yawing moment that rotated the body in the counterclockwise direction from a dorsal view, according to calculations from hydrodynamic theory. The tails of resting larvae were bent in the concave-left direction with a curvature statistically indistinguishable from the median value for tail curvature during swimming. The flexural stiffness of the tails of larvae, measured in three-point bending, may be great enough to allow the resting curvature of the tail to have an effect on the symmetry of kinematics. This work suggests that asymmetrical tail motion is an important mechanism for generating a yawing moment during swimming in ascidian larvae and that these asymmetries may be caused by the tail’s bent shape. Since helical motion requires that moments also be generated in the pitching or rolling directions, other mechanisms are required to explain fully how ascidian larvae generate and control helical swimming.

A three-dimensional shoulder protector based on ergonomics for workers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ran-i Eom ◽  
Yejin Lee
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
Health And Safety ◽  
The Body ◽  
Construction Sites ◽  
Content Type ◽  
Three Dimensional Printing ◽  
Functional Studies ◽  
Work Posture ◽  
Dimensional Printing

PurposeThe use of shoulder protectors is strongly recommended when carrying objects on the shoulder to ensure the health and safety of workers. Thus, this study aimed to develop and verify an ergonomic shoulder protector that considers human body shape and carrying posture from an ergonomic perspective. Ultimately, this study will present a shoulder protector with enhanced fit and safety for carrying workers at construction sites.Design/methodology/approachThe shoulder protector was designed and printed using three-dimensional printing technology with variable side neck points and shoulder point heights to reflect the human body's shoulder line shape and to position the carried object stably on the shoulder. The developed shoulder protectors were evaluated in terms of their fit according to the work posture of the carrier, adherence upon motion and durability through structural analysis.FindingsThe design of the shoulder protector for carrying workers followed the shoulder line. It is best placed above the side neck point by 1.0 cm and above the shoulder point by 2.0 cm. Its length is slightly shorter than the human shoulder for superior fit and safety.Originality/valueThe final shoulder protector (FSP) for carrying workers reflects the body curvature while enhancing fit and safety by considering activity and protective factors. As functional studies and evaluations on the need for protectors are scarce, this study provides fundamental data in the evaluation of protective gears.

The Body Design and Body Flow Passage Digital Simulation Analysis of the Solar Car

2013 ◽  
Vol 364 ◽  
pp. 14-18
Author(s):  
Xuan Zuo Liu ◽  
Hui Min Wang ◽  
Fei Zhang ◽  
Yu Long Zhang ◽  
Qian Cheng Liu
Keyword(s):  
Theoretical Basis ◽  
Body Shape ◽  
Simulation Analysis ◽  
Digital Simulation ◽  
Three Dimensional ◽  
The Body ◽  
Air Resistance ◽  
The World ◽  
Body Design ◽  
Design And Manufacture

This paper designs the three-dimensional body modelling of a solar car prototype mainly according to the World Solar Challenge rules, and carries on the flow field digital simulation analysis. This paper analyzes the air resistance of the car body and adjusts to the body shape, and ultimately gets a model well accorded with air dynamics. This paper provides scientific theoretical basis for the design and manufacture of the solar car prototype.

Analysis on Structure and Morphological of Carton Packaging

2013 ◽  
Vol 442 ◽  
pp. 338-341
Author(s):  
A Qiang Sun
Keyword(s):  
Structural Design ◽  
Body Shape ◽  
Space Form ◽  
Dimensional Space ◽  
Three Dimensional ◽  
The Body ◽  
Packaging Materials ◽  
Paper Study ◽  
Structural Morphology ◽  
Three Dimensional Space

The package structure is a three-dimensional space form, so people know the products are in used in the packaging. In packaging materials for paper use is very extensive, paper products are easy to shape the body shape for easy printing and recyclable advantage. This paper study design of the paper packaging structural, combining paper packaging structural design applications to explore the paper packaging structural morphology and environmentalist design consciousness.

scholarly journals Controlling Mixing Inside a Droplet by Time Dependent Rigid-Body Rotation

2008 ◽  
Author(s):  
Rodolphe Chabreyrie ◽  
Dmitri Vainchtein ◽  
Cristel Chandre ◽  
Pushpendra Singh ◽  
Nadine Aubry
Keyword(s):  
Rigid Body ◽  
Liquid Droplet ◽  
Three Dimensional ◽  
Time Dependent ◽  
Mixing Enhancement ◽  
Body Rotation ◽  
Rigid Body Rotation ◽  
Digital Microfluidic ◽  
And Control ◽  
Time Periodic

The use of microscopic discrete fluid volumes (i.e., droplets) as microreactors for digital microfluidic applications often requires mixing enhancement and control within droplets. In this work, we consider a translating spherical liquid droplet to which we impose a time periodic rigid-body rotation which we model using the superposition of a Hill vortex and an unsteady rigid body rotation. This perturbation in the form of a rotation not only creates a three-dimensional chaotic mixing region, which operates through the stretching and folding of material lines, but also offers the possibility of controlling both the size and the location of the mixing. Such a control is achieved by judiciously adjusting the three parameters that characterize the rotation, i.e., the rotation amplitude, frequency and orientation of the rotation. As the size of the mixing region is increased, complete mixing within the drop is obtained.

scholarly journals Strength and Service Life of a Steam Turbine Stop and Control Valve Body

2021 ◽  
Vol 24 (4) ◽  
pp. 61-70 ◽  
Author(s):  
Andrii S. Koliadiuk ◽  
◽  
Mykola H. Shulzhenko ◽  
Oleksandr M. Hubskyi ◽  
◽  
...  
Keyword(s):  
Service Life ◽  
Steam Turbine ◽  
Three Dimensional ◽  
The Body ◽  
Valve Body ◽  
Control Valves ◽  
Operating Modes ◽  
And Control ◽  
Inlet Chamber ◽  
Creep Strains

The stability of operation of steam turbines depends (along with other factors) on the reliable operation of their steam distribution systems, which are based on stop and control valves. This paper considers the strength of the elements of the K-325-23.5 steam turbine valves, in whose bodies, after 30 thousand hours of operation, cracks came to be observed. Previously determined were the nature of gas-dynamic processes in the flow paths of the valves and the temperature state of the valve body in the main stationary modes of operation. To do this, a combined problem of steam flow and thermal conductivity in stop and control valves was solved in a three-dimensional formulation by the finite element method. Different positions of the valve elements were considered taking into account the filter sieve. The assessment of the thermal stress state of the valve body showed that the maximum stresses in different operating modes do not exceed the yield strength. Therefore, the assessment of the creep of the valve body material is important to determine the valve body damage and service life. Modeling the creep of the stop and control valves of the turbine was performed on the basis of three-dimensional models, using the theory of hardening, with the components of unstable and steady creep strains taken into account. The creep was determined at the maximum power of the turbine for all the stationary operating modes. The maximum calculated values of creep strains are concentrated in the valve body branch pipes before the control valves and in the steam inlet chamber, where in practice fatigue defects are observed. However, even for 300 thousand hours of operation of the turbine (with a conditional maximum power) in stationary modes, creep strains do not exceed admissible values. The damage and service life of the valve bodies were assessed by two methods developed at A. Pidhornyi Institute of Mechanical Engineering Problems of the NAS of Ukraine (2011), and I. Polzunov Scientific and Design Association on Research and Design of Power Equipment. (NPO CKTI) – 1986. The results of assessing the damage and the turbine valve body wear from the effects of cyclic loading and creep of the turbine in stationary modes for 40, 200 and 300 thousand hours show that the thermal conditions of the body in the steam inlet chamber are not violated (without taking into account possible body defects after manufacture). The damage in valve body branch pipes after 300 thousand hours of operation exceeds the admissible value, with account taken of the safety margin. At the same time, the damage from creep in stationary operating modes is about 70% of the total damage. The maximum values of damage are observed in the areas of the body where there are defects during the operation of the turbine steam distribution system. The difference between the results of both methods in relation to their average value is ~20%.

scholarly journals Countershading enhances camouflage by reducing prey contrast

2020 ◽  
Vol 287 (1927) ◽  
pp. 20200477
Author(s):  
Callum G. Donohue ◽  
Jan M. Hemmi ◽  
Jennifer L. Kelley
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
Luminance Contrast ◽  
The Body ◽  
Body Parts ◽  
Live Fish ◽  
Average Luminance ◽  
Fish Predators ◽  
Dimensional Shape ◽  
Three Dimensional Shape

A three-dimensional body shape is problematic for camouflage because overhead lighting produces a luminance gradient across the body's surface. Countershading, a form of patterning where animals are darkest on their uppermost surface, is thought to counteract this luminance gradient and enhance concealment, but the mechanisms of protection remain unclear. Surprisingly, no study has examined how countershading alters prey contrast, or investigated how the presence of a dorsoventral luminance gradient affects detection under controlled viewing conditions. It has also been suggested that the direction of the dorsoventral luminance gradient (darkest or lightest on top) may interfere with predators' abilities to resolve prey's three-dimensional shape, yet this intriguing idea has never been tested. We used live fish predators (western rainbowfish, Melanotaenia australis ) and computer-generated prey images to compare the detectability of uniformly pigmented (i.e. non-countershaded) prey with that of optimally countershaded prey of varying contrasts against the background. Optimally countershaded prey were difficult for predators to detect, and the probability and speed of detection depended on prey luminance contrast with the background. In comparison, non-countershaded prey were always highly detectable, even though their average luminance closely matched the luminance of the background. Our findings suggest that uniformly pigmented three-dimensional prey are highly conspicuous to predators because overhead lighting increases luminance contrast between different body parts or between the body and the background. We found no evidence for the notion that countershading interferes with predator perception of three-dimensional form.

Subcritical Flow without Circulation past a Swept Semi-Infinite Elliptic Cylinder

1977 ◽  
Vol 28 (2) ◽  
pp. 142-148 ◽  
Author(s):  
G J Clapworthy
Keyword(s):  
Body Shape ◽  
Velocity Potential ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Elliptic Cylinder ◽  
The Body ◽  
Infinite Domain ◽  
Working Space ◽  
Mach Number Distribution ◽  
Grid Points

SummaryThe numerical calculation of the subcritical, steady, three-dimensional, potential flow past a semi-infinite swept elliptic cylinder attached to a plane wall is described. The full equations of motion are written in terms of the velocity potential and the exact body-surface conditions are applied. The equations are expressed in coordinates defined by the body shape and further transformations are necessary to reduce the infinite domain to a finite working space and to concentrate the grid points in regions of greatest variation of potential. The resulting equations are solved using a finite-difference scheme. The Mach number distribution for a typical case is presented.

scholarly journals Structural similarities in the CPC clip motif explain peptide-binding promiscuity between glycosaminoglycans and lipopolysaccharides

2017 ◽  
Vol 14 (136) ◽  
pp. 20170423 ◽  
Author(s):  
David Pulido ◽  
Rocío Rebollido-Rios ◽  
Javier Valle ◽  
David Andreu ◽  
Ester Boix ◽  
...  
Keyword(s):  
Binding Sites ◽  
Three Dimensional ◽  
The Body ◽  
Heparin Binding ◽  
Structural Determinants ◽  
E Coli ◽  
High Affinity ◽  
Structural Framework ◽  
And Control ◽  
Proteins And Peptides

Lipopolysaccharides (LPSs) and glycosaminoglycans (GAGs) are polymeric structures containing negatively charged disaccharide units that bind to specialized proteins and peptides in the human body and control fundamental processes such as inflammation and coagulation. Surprisingly, some proteins can bind both LPSs and GAGs with high affinity, suggesting that a cross-communication between these two pathways can occur. Here, we explore whether GAGs and LPSs can share common binding sites in proteins and what are the structural determinants of this binding. We found that the LPS-binding peptide YI12WF, derived from protein FhuA, can bind both heparin and E. coli LPS with high affinity. Most interestingly, mutations decreasing heparin binding in the peptide also reduce LPS affinity. We show that such mutations involve the CPC clip motif in the peptide, a small three-dimensional signature required for heparin binding. Overall, we conclude that negatively charged polysaccharide-containing polymers such as GAGs and LPSs can compete for similar binding sites in proteins, and that the CPC clip motif is essential to bind both ligands. Our results provide a structural framework to explain why these polymers can cross-interact with the same proteins and peptides and thus contribute to the regulation of apparently unrelated processes in the body.

Classification of body shape characteristics of women's torsos using angles

2010 ◽  
Vol 22 (4) ◽  
pp. 297-311 ◽  
Author(s):  
Wookyung Lee ◽  
Haruki Imaoka
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
The Body ◽  
Data Set ◽  
Content Type ◽  
Body Sizes ◽  
Body Shapes ◽  
Three Body ◽  
Shape Characteristics

PurposeThe purpose of this paper is to classify body shapes using angular defects instead of sizes.Design/methodology/approachA large amount of dimensional data from a national anthropometry survey was analysed, and a basic pattern and its polyhedron were also used to create a three‐dimensional body shape from three body sizes. Using this method, the sizes were converted into nine angular defects.FindingsThe authors could define the factors explaining body shape characteristics and classify the body shapes into four groups. The four groups could be characterised by two pattern making difficulties of the upper and lower parts of the body as well as by two proportions, of waist girth to bust girth and bust girth to back length. Furthermore, depending on the age, the authors could understand body shape by the angle made.Originality/valueUsing a polyhedron model, the angles could be calculated using an enormous existing data set of sizes. An angular defect serves as an index to indicate the degree of difficulty for developing a flat pattern. If an angular defect of the bust is large, it is difficult to make a paper pattern of a bust dart. On the other hand, if an angular defect of the waist is large, it is easy to make a paper pattern of a waist dart. Thus, each body shape could be simultaneously characterized by two difficulty indices and two proportions of sizes.

scholarly journals Effects of Diversified Sports Activity Module on Physical Fitness and Mental Health of 4–5-Year-Old Preschoolers

2021 ◽  
Author(s):  
Jinfu Liu ◽  
Feng Gao ◽  
Lugang Yuan
Keyword(s):  
Mental Health ◽  
Physical Fitness ◽  
Body Shape ◽  
The Body ◽  
Control Group ◽  
Sports Activity ◽  
Standing Long Jump ◽  
Long Jump ◽  
And Control ◽  
Experimental Group

Background: Chinese children are poorer in sports activity as compared to foreign children and their prospects as to physical fitness are not optimistic. This study aimed to discuss the effects of diversified sports activity modules on physical fitness and mental health of preschoolers ages 4–5 years. Methods: Sixty preschoolers aged 4–5-yr-old from two kindergartens in Jiaxing of China were selected randomly during Mar-Oct 2019. These respondents were divided into the experimental group (n=30) and the control group (n=30). The experimental group implemented the diversified sports activity module for 16 wk successively, 5 d per week, and 30-45 min per day. The control group adopted conventional sports activity. The body shape, physical fitness, and mental health of the two groups were measured and compared. Results: For body shape, the height of the experimental group increased is significantly higher than that of the control group. The experimental and control groups show no significant differences in body weight. For physical fitness, the experimental group is significantly superior to the control group in testing results of standing long jump, double-feet continuous jump, balancing on one foot, tennis shot, sit-and-reach, and 10 m repeated run. For mental health, the testing results of action development, language development, and social development of the experimental group are significantly better than those of the control group. Conclusion: The diversified sports activity module is not only conducive to strengthening the physical fitness of 4–5-year-old preschoolers but also improves their mental health.

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