scholarly journals Rachis morphology cannot accurately predict the mechanical performance of primary feathers in extant (and therefore fossil) feathered flyers

2017 ◽  
Vol 4 (2) ◽  
pp. 160927 ◽  
Author(s):  
John Lees ◽  
Terence Garner ◽  
Glen Cooper ◽  
Robert Nudds
Keyword(s):  
Structural Properties ◽  
Mechanical Performance ◽  
Bending Moment ◽  
Precise Determination ◽  
External Diameter ◽  
Strongly Correlated ◽  
Primary Feather ◽  
Second Moment ◽  
Three Point Bending

It was previously suggested that the flight ability of feathered fossils could be hypothesized from the diameter of their feather rachises. Central to the idea is the unvalidated assumption that the strength of a primary flight feather (i.e. its material and structural properties) may be consistently calculated from the external diameter of the feather rachis, which is the only dimension that is likely to relate to structural properties available from fossils. Here, using three-point bending tests, the relationship between feather structural properties (maximum bending moment, M max and Young's modulus, E bend ) and external morphological parameters (primary feather rachis length, diameter and second moment of area at the calamus) in 180 primary feathers from four species of bird of differing flight style was investigated. Intraspecifically, both E bend and M max were strongly correlated with morphology, decreasing and increasing, respectively, with all three morphological measures. Without accounting for species, however, external morphology was a poor predictor of rachis structural properties, meaning that precise determination of aerial performance in extinct, feathered species from external rachis dimensions alone is not possible. Even if it were possible to calculate the second moment of area of the rachis, our data suggest that feather strength could still not be reliably estimated.

scholarly journals Landfill Slope Stability Improvement Incorporating Reinforcements in Reclamation Process Applying Observational Method

2020 ◽  
Vol 10 (5) ◽  
pp. 1572 ◽  
Author(s):  
Eugeniusz Koda ◽  
Agnieszka Kiersnowska ◽  
Jacek Kawalec ◽  
Piotr Osiński
Keyword(s):  
Slope Stability ◽  
Mechanical Performance ◽  
Safety Management ◽  
Precise Determination ◽  
Observational Method ◽  
New Development ◽  
Complex Engineering ◽  
Reclamation Plan ◽  
The Stability

This paper concerns a case study presenting one of the biggest landfills in Poland that required application of complex engineering works to extend the deposing capacity of the structure. The shear strength parameters of the subsoil and waste material used for analyses were based on geotechnical investigation and were then applied in slope stability analyses of the landfill. For the purpose of safety management of the new development and reclamation plan for the landfill, an observational method was applied to increase the geotechnical safety of the structure. The slope reinforcement methods mainly included the geogrid, geocomposite, and berms construction. However, much of the uncertainty associated with the stability of the geogrid-reinforced slope is related to the time-dependent deformation of geosynthetic materials. For the purpose of changes in the geogrid parameters with time, the samples were excavated from the landfill slope after 20 years of exploitation and analyzed in the laboratory. The tests allowed precise determination of the material properties, changing geometry, and mechanical properties like tensile strength and strain. Obtained results were compared to parameters of the brand-new geogrid samples. The tests indicated only insignificant changes in geosynthetics, physical, or mechanical performance properties, and the slope has not been compromised in its stability or performance.

PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

2010 ◽  
Vol 46 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Yang MENG ◽  
Lin GU ◽  
Wenzheng ZHANG
Keyword(s):  
Precise Determination ◽  
Interface Orientation

Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

1968 ◽  
Vol 12 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Basal Area ◽  
Precise Determination ◽  
Maximum Diameter ◽  
Precise Method ◽  
Maximum Radius ◽  
The Core ◽  
Two Parameters

A precise method for the determination of the increment of the  basal area using the PressIer bore. Refering to  previous research showing that the basal area of the corsica pine could be  characterized by an ellips, we present in this paper a precise method for the  determination of the increment of the basal area. In this method we determine  the direction of the maximum diameter, we measure this diameter and we take a  core in one of the points of tangency of the caliper with the measured tree.  The determination of the diameter perpendicular to the maximum diameter  finishes the work wich is to be done in the forest. From the classical  measurements effectuated on the core and from the measured diameters we can  then determine the form (V) and the excentricity (e). Substituting these two  parameters in the formula 2 or 2', we can also calculate the error of a  radius measured on the core with respect to the representative radius, This  error with them allow us to correct the measured value of the minimum or the  maximum radius and we will be able to do a precise determination of the  increment.

scholarly journals A single-step purification method for the precise determination of the antimony isotopic composition of environmental, geological and biological samples by HG-MC-ICP-MS

2021 ◽  
Author(s):  
Ferrari Colin ◽  
Resongles Eléonore ◽  
Freydier Rémi ◽  
Casiot Corinne
Keyword(s):  
Isotopic Composition ◽  
Biological Samples ◽  
Precise Determination ◽  
Single Step ◽  
Functionalized Silica ◽  
Purification Method ◽  
Silica Powder ◽  
Icp Ms ◽  
Single Step Purification

Thiol-functionalized silica powder allowed single-step purification of antimony for exploring stable Sb isotope signatures in the environment.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

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