scholarly journals Form, function, and divergence of a generic fin shape in small cetaceans

2020 ◽  
Author(s):  
Vadim Pavlov ◽  
Cecile Vincent ◽  
Bjarni Mikkelsen ◽  
Justine Lebeau ◽  
Vincent Ridoux ◽  
...  
Keyword(s):  
Cross Sections ◽  
Evolutionary Process ◽  
Stability Control ◽  
Hydrodynamic Performance ◽  
Cross Sectional ◽  
Aquatic Life ◽  
Propulsive Efficiency ◽  
Dorsal Fin ◽  
Cross Sectional Design ◽  
Thrust Production

AbstractTail flukes as well as the dorsal fin are the apomorphic traits of cetaceans appeared during evolutionary process of adaptation to the aquatic life. Both appendages present a generic wing-like shape associated with lift generation and low drag. Variability of the form of appendages was studied in seven species of cetaceans having different body size, external morphology, and specialization. Hydrodynamic performance of the fin cross-sections was examined with the CFD software and compared with similar engineered airfoils. Affinity of hydrodynamic design of both appendages was found in a wing-like planform and cross-sectional design optimized for lift generation. Distinctions in the planform and cross-sections were found related with the fin specialization in thrust production or swimming stability control. Cross-sectional design of the dorsal fin was found to be optimized for the narrow range of small angles of attack. Cross-sections of tail flukes were found to be more stable for higher angles of attack and had gradual stall characteristics that is associated with their propulsive efficiency as oscillating foils. The results obtained are the evidence of divergent evolutionary pathways of a generic wing-like shape of the fins of cetaceans under specific demands of thrust production and swimming stability control.

scholarly journals Form, function, and divergence of a generic fin shape in small cetaceans

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255464
Author(s):  
Vadim Pavlov ◽  
Cecile Vincent ◽  
Bjarni Mikkelsen ◽  
Justine Lebeau ◽  
Vincent Ridoux ◽  
...  
Keyword(s):  
Body Length ◽  
Cross Sections ◽  
The Body ◽  
Hydrodynamic Characteristics ◽  
Wing Design ◽  
Cross Sectional ◽  
Aquatic Life ◽  
Dorsal Fin ◽  
Primary Function ◽  
Fin Shape

Tail flukes as well as the dorsal fin are the apomorphic traits of cetaceans which appeared during the evolutionary process of adaptation to the aquatic life. Both appendages present a wing-like shape associated with lift generation and low drag. We hypothesized that the evolution of fins as lifting structures led to a generic wing design, where the dimensionless parameters of the fin cross-sections are invariant with respect to the body length and taxonomy of small cetaceans (Hypothesis I). We also hypothesized that constraints on variability of a generic fin shape are associated with the primary function of the fin as a fixed or flapping hydrofoil (Hypothesis II). To verify these hypotheses, we examined how the variation in the fin’s morphological traits is linked to the primary function, species and body length. Hydrodynamic characteristics of the fin cross-sections were examined with the CFD software and compared with similar engineered airfoils. Generic wing design of both fins was found in a wing-like planform and a streamlined cross-sectional geometry optimized for lift generation. Divergence in a generic fin shape both on the planform and cross-sectional level was found to be related with the fin specialization in fixed or flapping hydrofoil function. Cross-sections of the dorsal fin were found to be optimized for the narrow range of small angles of attack. Cross-sections of tail flukes were found to be more stable for higher angles of attack and had gradual stall characteristics. The obtained results provide an insight into the divergent evolutionary pathways of a generic wing-like shape of the fins of cetaceans under specific demands of thrust production, swimming stability and turning control.

Friction, Contact Pressure, and Nonlinear Behavior of Steel Tubes in Subsea Umbilicals

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Farzan Parsinejad ◽  
Chris Kassner ◽  
Mark Kurtz ◽  
Naiquan Ye
Keyword(s):  
Contact Pressure ◽  
Fatigue Damage ◽  
Cross Sections ◽  
Contact Stiffness ◽  
Global Analysis ◽  
Nonlinear Behavior ◽  
Steel Tubes ◽  
Cross Sectional ◽  
Cross Sectional Design ◽  
The Impact

This paper focuses on evaluating the impact of friction and contact pressure on helical steel tubes. The initial gaps between steel tubes and adjacent layers, friction coefficients and the contact stiffness are the main factors that affect such investigation. A novel methodology by using UFLEX2D (a MARINTEK product) has been applied for modeling complex umbilical cross sections and for the study of these parameters. Two cross sections for the same subsea application but with different designs have been investigated in the study. It has been shown how fatigue damage can be significantly impacted by different cross-sectional design. For this study, nonlinear moment/curvature relationship has been included in the analyses. Based on the findings of this study, more realistic results can be achieved by including the nonlinear behavior in global analysis for fatigue damage calculations instead of using nominal bending stiffness supplied by umbilical manufacturer.

scholarly journals Effect of Nonuniform Flexibility on Hydrodynamic Performance of Pitching Propulsors

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Samane Zeyghami ◽  
Keith W. Moored
Keyword(s):  
Structural Model ◽  
Fluid Model ◽  
Leading Edge ◽  
Functionally Graded ◽  
Hydrodynamic Performance ◽  
Propulsive Efficiency ◽  
Fluid Structure ◽  
Structure System ◽  
Torsional Spring ◽  
Thrust Production

Many aquatic animals propel themselves efficiently through the water by oscillating flexible fins. These fins are, however, not homogeneously flexible, but instead their flexural stiffness varies along their chord and span. Here, we develop a simple model of these functionally graded materials where the chordwise flexibility of the foil is modeled by one or two torsional springs along the chord line. The torsional spring structural model is then strongly coupled to a boundary element fluid model to simulate the fluid–structure interactions. We show that the effective flexibility of the combined fluid–structure system scales with the ratio of the added mass forces acting on the passive portion of the foil and the elastic forces defined by the torsional spring hinge. Importantly, by considering this new scaling of the effective flexibility, the propulsive performance is then detailed for a foil with a flexible hinge that is actively pitching about its leading edge. The scaling allows for the resonance frequency of the fluid–structure system and the bending pattern of the propulsor to be independently varied by altering the effective flexibility and the location of a single torsional spring along the chord, respectively. It is shown that increasing the flexion ratio, by moving the spring away from the leading edge, leads to enhanced propulsive efficiency, but compromises the thrust production. Proper combination of two flexible hinges, however, can result in a gain in both the thrust production and propulsive efficiency.

scholarly journals The effect of handrail cross-sectional design and age on applied handrail forces during reach-to-grasp balance reactions

2021 ◽  
Author(s):  
Philippa Gosine ◽  
Vicki Komisar ◽  
Alison C. Novak
Keyword(s):  
Older Adults ◽  
Cross Sections ◽  
Resultant Force ◽  
Force Generation ◽  
Reach To Grasp ◽  
Cross Sectional ◽  
Younger Adults ◽  
Cross Sectional Design ◽  
Balance Loss ◽  
Shape And Size

AbstractHandrails have been shown to reduce the likelihood of falls. Despite common use, little is known about how handrail shape and size affect the forces that people can apply after balance loss, and how these forces and the corresponding ability to recover balance depend on age. Following rapid platform translations, 16 older adults and 16 sex-matched younger adults recovered their balance using seven handrail cross-sections varying in shape and size. Younger adults were able to withstand higher perturbations, but did not apply higher forces, than older adults. However, younger adults achieved their peak resultant force more quickly, which may reflect slower rates of force generation with older adults. Considering handrail design, the 38mm round handrails allowed participants to successfully recover from the largest perturbations and enabled the highest force generation. Conversely, tapered handrails had the poorest performance, resulting in the lowest force generation and withstood perturbation magnitudes. Our findings suggest that the handrail cross-sectional design affects the magnitude of force generation and may impact the success of recovery. Our findings can inform handrail design recommendations that support effective handrail use in demanding, balance recovery scenarios.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Relationship of Self-Compassion, Hope, and Emotional Control to Perceived Burdensomeness, Thwarted Belongingness, and Suicidal Ideation

Crisis ◽  
2020 ◽  
pp. 1-7
Author(s):  
Laura R. Umphrey ◽  
John C. Sherblom ◽  
Paulina Swiatkowski
Keyword(s):  
College Students ◽  
Suicidal Ideation ◽  
Emotional Control ◽  
Thwarted Belongingness ◽  
Perceived Burdensomeness ◽  
Cross Sectional ◽  
Self Compassion ◽  
Positive Feelings ◽  
Cross Sectional Design ◽  
Relationship Of

Abstract. Background: Cultivating positive feelings of self in relationships with others can affect perceptions of belongingness and burdensomeness. Aims: The present study examines the relationships of self-compassion, hope, and emotional control to thwarted belongingness, perceived burdensomeness, and suicidal ideation. Method: Participants were 481 college students who completed scales measuring self-compassion, hope, emotional control, thwarted belongingness, perceived burdensomeness, and suicidal ideation. Results: Correlation and parallel mediation analysis results show relationships between self-compassion, hope, and emotional control with perceived burdensomeness, thwarted belongingness, and suicidal ideation. Limitations: The study is limited by its cross-sectional design, sample demographics, and inability to distinguish between individuals with suicidal ideation and those who attempt suicide. Conclusion: The results show that the relationships of self-compassion, hope, and emotional control to perceived burdensomeness, thwarted belongingness, and suicidal ideation are worth further investigation.

Rorschach-CS Scores of Six Groups of Patients

2013 ◽  
Vol 34 (1) ◽  
pp. 24-55 ◽  
Author(s):  
Caspar C. Berghout ◽  
Jolien Zevalkink ◽  
Abraham N. J. Pieters ◽  
Gregory J. Meyer
Keyword(s):  
Mental Health ◽  
Health Care ◽  
Health Care Organizations ◽  
Total Sample ◽  
Psychoanalytic Psychotherapy ◽  
Cross Sectional ◽  
Treatment Groups ◽  
Treatment Type ◽  
Psychotherapy Groups ◽  
Cross Sectional Design

In this study we used a quasiexperimental, cross-sectional design with six cohorts differing in phase of treatment (pretreatment, posttreatment, 2-year posttreatment) and treatment type (psychoanalysis and psychoanalytic psychotherapy) and investigated scores on 39 Rorschach-CS variables. The total sample consisted of 176 participants from four mental health care organizations in The Netherlands. We first examined pretreatment differences between patients entering psychoanalysis and patients entering psychoanalytic psychotherapy. The two treatment groups did not seem to differ substantially before treatment, with the exception of the level of ideational problems. Next, we studied the outcome of psychoanalysis and psychoanalytic psychotherapy by comparing the Rorschach-CS scores of the six groups of patients. In general, we found significant differences between pretreatment and posttreatment on a relatively small number of Rorschach-CS variables. More pre/post differences were found between the psychoanalytic psychotherapy groups than between the psychoanalysis groups. More research is needed to examine whether analyzing clusters of variables might reveal other results.

HUBUNGAN LAMA WAKTU MENDERITA STROKE DENGAN TINGKAT KEMANDIRIAN KLIEN DALAM MELAKUKAN AKTIVITAS PEMENUHAN KEBUTUHAN SEHARI-HARI

2018 ◽  
Vol 1 (2) ◽  
pp. 58
Author(s):  
Setia Budi ◽  
Ria Dila Syahfitri
Keyword(s):  
Data Analysis ◽  
Univariate Analysis ◽  
Sampling Technique ◽  
P Value ◽  
Cross Sectional ◽  
Stroke Incidence ◽  
Bivariate Data ◽  
Cross Sectional Design ◽  
Interviewing Techniques ◽  
Need For Rehabilitation

The rate of stroke incidence is about 200 per 100,000 people throughout the world. This study aims to determine the Relation Suffer Stroke With Independence Level In Neurology Polyclinic TK II DR Ak Gani Palembang Year Hospital 2017. The research method used is descriptive quantitative with cross sectional design that is done by interviewing techniques with questionnaires on 42 respondents with Accidental sampling technique. This research was conducted in August 2017. Data analysis used is univariate data analysis and bivariate data analysis with one way anova test result. The results of univariate analysis showed that the duration of the respondents suffering from stroke was between 2.10 years to 3.38 years. Also found that most respondents were at the level of independence f; independent, except bathing, dressing, moving, and one other function with a total of 12 respondents. The results showed that there was a significant relationship between the long suffering stroke with the level of independence with the value of p value 0.025. For that the need for rehabilitation to patients and families of patients in order to help improve the independence of stroke patients in doing their daily activities. Keywords : Long Suffer Stroke, Level of Independence

The Correlation of the Limitations of Movement of the Shoulder Joint with the Functional Ability of Frozen Shoulder Patients at the Medical Rehabilitation Institute Dr. Mohammad Hoesin Palembang

2020 ◽  
Vol 3 (3) ◽  
pp. 88-96
Author(s):  
Ine Sintia ◽  
Nyimas Fatimah
Keyword(s):  
Functional Ability ◽  
Shoulder Joint ◽  
Frozen Shoulder ◽  
Limited Range ◽  
Medical Rehabilitation ◽  
Cross Sectional ◽  
Shoulder Joints ◽  
Limited Range Of Motion ◽  
Active Flexion ◽  
Cross Sectional Design

Background: Frozen shoulder is a condition of the shoulder joint that experiences inflammation, pain, adhesions, atrophyand shortening of the joint capsule resulting in limited motion. In frozen shoulder patients, the limited range of motion ofthe shoulder joint can affect and reduce functional ability. This study aims to analyze the correlation between the limitedarea of motion of the shoulder joint with the functional ability of frozen shoulder patients at the Medical RehabilitationInstallation Dr. Mohammad Hoesin Palembang. Methods: This study was an observational analytic study, correlationtest, with a cross sectional design. There were 29 frozen shoulder patients who met the inclusion criteria in the MedicalRehabilitation Installation Dr. Mohammad Hoesin Palembang in November 2018 was taken as a sample using consecutivesampling techniques. Functional ability was assessed using the quickDASH questionnaire and the area of motion wasmeasured using a goniometer, then analyzed. Results: The results of the correlation test showed significant resultsbetween functional abilities and the area of motion of the shoulder joints. Active flexion (p = 0.000; r = -0.669), activeextension (p = 0.004; r = -0.520), active abduction (p = 0.000; r = -0.663), active adduction (p = 0.022; r = -0.423 ), passiveflexion (p = 0.001; r = -0.589), passive extension (p = 0.002; r = -0.543), passive abduction (p = 0.000; r = -0.676), passiveadduction (p = 0.038; r = -0.388). Conclusion: There is a significant correlation between limited joint motion andfunctional ability in frozen shoulder patients at the Medical Rehabilitation Installation of Dr. Mohammad HoesinPalembang

HUBUNGAN DUKUNGAN KELUARGA, PENGETAHUAN, DENGAN KEAKTIFAN LANJUT USIA (Lansia) MENGIKUTI KEGIATAN POSYANDU LANSIA DI WILAYAH PUSKESMAS GADING SURABAYA

2020 ◽  
Vol 4 (1) ◽  
pp. 1-6
Author(s):  
NINDY VARA MEIGIA
Keyword(s):  
Health Center ◽  
Family Support ◽  
Elderly People ◽  
Simple Random Sampling ◽  
The Elderly ◽  
Design Data ◽  
Cross Sectional ◽  
Bivariate Data ◽  
Quality Regulation ◽  
Cross Sectional Design

Minimum Standards Service is basic service quality regulation that is entitled to be obtained by every citizen. Elderly people must obtain 100% health services. Various factors can lead to low visits to the elderly posyandu in the Gading Puskesmas area in 2017. Objective: to find out the relationship between family support, knowledge, and elderly activities in the elderly posyandu in Gading Surabaya puskesmas. Method: The type of research is observational analytic with a cross-sectional design. Data processing and analysis is done by univariate and bivariate. Data collection techniques by conducting simple random sampling with a sample of 94 elderly people. Location and time of research from December 2018 at the posyandu in the Gading Surabaya health center area. Results: There is a significant value of 0,000 <0,05, so it can be concluded is have a relationship with family support, knowledge of elderly with activity following the elderly posyandu at Gading Surabaya health center

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