scholarly journals Egg Incubation Mechanics of Giant Birds

Biology ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 738
Author(s):  
An Yen ◽  
Hsiao-Jou Wu ◽  
Pin-Yi Chen ◽  
Hon-Tsen Yu ◽  
Jia-Yang Juang
Keyword(s):  
Body Mass ◽  
Sexual Size Dimorphism ◽  
Mechanical Characteristics ◽  
Safety Margin ◽  
Dimensionless Number ◽  
Element Analysis ◽  
Egg Incubation ◽  
Safety Margins ◽  
Reversed Sexual Size Dimorphism ◽  
Maximum Body

Finite element analysis (FEA) was used to conduct mechanical analyses on eggshells of giant birds, and relate this to the evolution and reproductive behavior of avian species. We aim to (1) investigate mechanical characteristics of eggshell structures of various ratite species, enabling comparisons between species with or without reversed sexual size dimorphism (RSSD); (2) quantify the safety margin provided by RSSD; (3) determine whether the Williams’ egg can have been incubated by an extinct giant bird Genyornis newtoni; (4) determine the theoretical maximum body mass for contact incubation. We use a dimensionless number C to quantify relative shell stiffness with respect to the egg size, allowing for comparison across wide body masses. We find that RSSD in moas significantly increases the safety margin of contact incubation by the lighter males. However, their safety margins are still smaller than those of the moa species without RSSD. Two different strategies were adopted by giant birds—one is RSSD and thinner shells, represented by some moa species; the other is no RSSD and regular shells, represented by the giant elephant bird. Finally, we predicted that the upper limit of body mass for contact incubation was 2000 kg.

Experimental Study on Ultimate Strength of Single and Double Type Bellows Under Internal Pressure

2016 ◽  
Author(s):  
Masanori Ando ◽  
Hiroki Yada ◽  
Kazuyuki Tsukimori ◽  
Masakazu Ichimiya ◽  
Yoshinari Anoda
Keyword(s):  
Internal Pressure ◽  
Fast Reactor ◽  
Evaluation Method ◽  
Safety Margin ◽  
External Pressure ◽  
Element Analysis ◽  
Primary Coolant ◽  
Containment Vessel ◽  
Safety Margins ◽  
Intermediate Heat Exchanger

Containment vessel is an important structure to prevent a significant and sudden radioactive release, however, the safety margin of the containment vessel against the internal or external pressure are not numerically clarified. Namely, the safety margins due to the relationship of the ultimate toughness of containment vessel structures and maximum design pressure is not clear. Indeed, to clarify the progress of the events under the beyond design basis events (BDBE) and to design the BDBE countermeasure equipment, it is necessary to evaluate the pressure toughness of containment vessel adequately. The containment vessel of fast reactor is composed of the various structures, and one of the thinnest boundary structures is bellows structure to absorb the thermal expansion of the coolant piping penetrating the containment vessel. In addition to the containment vessel boundary, evaluating the pressure toughness of reactor coolant and gas boundary is also important because of same reason of that in the containment vessel boundary. In the primary coolant and gas boundary, the cover gas bellows of the intermediate heat exchanger in fast reactor is one of the thinnest structures and has important role when the progress of the BDBE is considered. Therefore, in order to develop the evaluation method of the pressure toughness of bellows structure under the BDBE, the pressure failure tests and finite element analysis of the bellows structure subjected to internal pressure were performed in this study.

scholarly journals Bootstrap and Order Statistics for Quantifying Thermal-Hydraulic Code Uncertainties in the Estimation of Safety Margins

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Enrico Zio ◽  
Francesco Di Maio
Keyword(s):  
Confidence Interval ◽  
Order Statistics ◽  
Nuclear Reactor ◽  
Safety Margin ◽  
Fuel Cladding ◽  
Complete Group ◽  
Bootstrap Technique ◽  
Safety Margins ◽  
Group Distribution

In the present work, the uncertainties affecting the safety margins estimated from thermal-hydraulic code calculations are captured quantitatively by resorting to the order statistics and the bootstrap technique. The proposed framework of analysis is applied to the estimation of the safety margin, with its confidence interval, of the maximum fuel cladding temperature reached during a complete group distribution blockage scenario in a RBMK-1500 nuclear reactor.

Investigation of Burst Pressure in T-Joints With Wall-Thinning by Using FEA

2017 ◽  
Author(s):  
Atsushi Yamaguchi
Keyword(s):  
Carrying Capacity ◽  
Safety Margin ◽  
Pressure Vessels ◽  
Burst Pressure ◽  
Load Carrying Capacity ◽  
Working Pressure ◽  
Element Analysis ◽  
T Joints ◽  
Wall Thinning ◽  
Load Carrying

Boilers and pressure vessels are heavily used in numerous industrial plants, and damaged equipment in the plants is often detected by visual inspection or non-destructive inspection techniques. The most common type of damage is wall thinning due to corrosion under insulation (CUI) or flow-accelerated corrosion (FAC), or both. Any damaged equipment must be repaired or replaced as necessary as soon as possible after damage has been detected. Moreover, optimization of the time required to replace damaged equipment by evaluating the load carrying capacity of boilers and pressure vessels with wall thinning is expected by engineers in the chemical industrial field. In the present study, finite element analysis (FEA) is used to evaluate the load carrying capacity in T-joints with wall thinning. Burst pressure is a measure of the load carrying capacity in T-joints with wall thinning. The T-joints subjected to burst testing are carbon steel tubes for pressure service STPG370 (JIS G3454). The burst pressure is investigated by comparing the results of burst testing with the results of FEA. Moreover, the maximum allowable working pressure (MAWP) of T-joints with wall thinning is calculated, and the safety margin for the burst pressure is investigated. The burst pressure in T-joints with wall thinning can be estimated the safety side using FEA regardless of whether the model is a shell model or a solid model. The MAWP is 2.6 MPa and has a safety margin 7.5 for burst pressure. Moreover, the MAWP is assessed the as a safety side, although the evaluation is too conservative for the burst pressure.

Evolution of body mass in the Pan-Alcidae (Aves, Charadriiformes): the effects of combining neontological and paleontological data

Paleobiology ◽  
2015 ◽  
Vol 42 (1) ◽  
pp. 8-26 ◽  
Author(s):  
N. Adam Smith
Keyword(s):  
Body Mass ◽  
Mass Range ◽  
Extinct Species ◽  
Paleontological Data ◽  
Ideal Candidate ◽  
Extant Species ◽  
Size Evolution ◽  
Body Size Evolution ◽  
Phylogenetic Hypotheses ◽  
Maximum Body

AbstractHypotheses regarding the evolution of many clades are often generated in the absence of data from the fossil record and potential biases introduced by exclusion of paleontological data are frequently ignored. With regard to body size evolution, extinct taxa are frequently excluded because of the lack of body mass estimates—making identification of reliable clade specific body mass estimators crucial to evaluating trends on paleontological timescales. Herein, I identify optimal osteological dimensions for estimating body mass in extinct species of Pan-Alcidae (Aves, Charadriiformes) and utilize newly generated estimates of body mass to demonstrate that the combination of neontological and paleontological data produces results that conflict with hypotheses generated when extant species data are analyzed in isolation. The wing-propelled diving Pan-Alcidae are an ideal candidate for comparing estimates of body mass evolution based only on extant taxa with estimates generated including fossils because extinct species diversity (≥31 species) exceeds extant diversity, includes examples from every extant genera, and because phylogenetic hypotheses of pan-alcid relationships are not restricted to the 23 extant species. Phylogenetically contextualized estimation of body mass values for extinct pan-alcids facilitated evaluation of broad scale trends in the evolution of pan-alcid body mass and generated new data bearing on the maximum body mass threshold for aerial flight in wing-propelled divers. The range of body mass in Pan-Alcidae is found to exceed that of all other clades of Charadriiformes (shorebirds and allies) and intraclade body mass variability is recognized as a recurring theme in the evolution of the clade. Finally, comparisons of pan-alcid body mass range with penguins and the extinct †Plotopteridae elucidate potentially shared constraints among phylogenetically disparate yet ecologically similar clades of wing-propelled divers.

scholarly journals Why female birds of prey are larger than males

2020 ◽  
Vol 129 (3) ◽  
pp. 532-542
Author(s):  
Jonny Schoenjahn ◽  
Chris R Pavey ◽  
Gimme H Walter
Keyword(s):  
Sexual Size Dimorphism ◽  
A Priori ◽  
Nest Defence ◽  
Birds Of Prey ◽  
Causal Process ◽  
Size Dimorphism ◽  
Substantial Body ◽  
Key Factor ◽  
Reversed Sexual Size Dimorphism ◽  
Passionate Debate

Abstract The causes of the reversed sexual size dimorphism (RSD; females larger than males) in birds of prey are subject to a centuries-old, passionate debate. A crucial difficulty is to distinguish whether the postulated benefits derive from the proposed causal process(es) or are incidental. After reviewing the existing literature, we present a methodology that overcomes this difficulty and renders unnecessary any speculative a priori distinctions between evolved function and incidental effects. We can thus justify the following novel version of the well-known nest defence hypothesis as the most likely to explain the phenomenon in all birds of prey that show RSD: if the female predominates in actively defending the eggs and young against predators, then she is the heavier sex, and her relatively greater body mass is adaptive. That is, heavier females are favoured (independently of males) by natural selection. The attractiveness of this hypothesis is that it has the potential to explain the phenomenon in all raptors exhibiting RSD, can deal with the exceptional cases in this group, explains the direction of the dimorphism, focuses on a key factor in the reproductive success of most raptors, is parsimonious, i.e. does not require supporting hypotheses, and is supported by a substantial body of evidence.

scholarly journals Reversed sexual size dimorphism: body size patterns in sexes of lesser kestrels (Falco naumanni) in the Ikh Nart Nature Reserve, Mongolia

2019 ◽  
Vol 12 (3) ◽  
pp. 363-368 ◽  
Author(s):  
Onolragchaa Ganbold ◽  
Richard P. Reading ◽  
Ganchimeg J. Wingard ◽  
Woon Kee Paek ◽  
Purevsuren Tsolmonjav ◽  
...  
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Nature Reserve ◽  
Size Dimorphism ◽  
Falco Naumanni ◽  
Reversed Sexual Size Dimorphism

scholarly journals Structural complexity of hunting habitat and territoriality increase the reversed sexual size dimorphism in diurnal raptors

2018 ◽  
Vol 49 (10) ◽  
pp. e01745 ◽  
Author(s):  
Lorenzo Pérez-Camacho ◽  
Sara Martínez-Hesterkamp ◽  
Salvador Rebollo ◽  
Gonzalo García-Salgado ◽  
Ignacio Morales-Castilla
Keyword(s):  
Sexual Size Dimorphism ◽  
Structural Complexity ◽  
Size Dimorphism ◽  
Reversed Sexual Size Dimorphism
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