Glossary entry (derived from question below)
French term or phrase:
empilement des oursins
English translation:
sea urchin stack
Added to glossary by
Yolanda Broad
Feb 26, 2018 20:42
6 yrs ago
2 viewers *
French term
empilement des oursins
French to English
Other
Mathematics & Statistics
architecture and isoceles triangles polyhedrons
Help please. These are various calculations. I can busk a lot of the terms and I will ask the customer to be sure.
Buy I wonder if anyone can help me with : l’empilement des “oursins - stacking of urchins? Does not seem very likely but....
Thanks in a advance
Buy I wonder if anyone can help me with : l’empilement des “oursins - stacking of urchins? Does not seem very likely but....
Thanks in a advance
Proposed translations
(English)
| 4 | sea urchin stack |
Francois Boye
|
Change log
Feb 28, 2018 23:34: Yolanda Broad changed "Term asked" from " l’empilement des “oursins" to " empilement des oursins"
Feb 28, 2018 23:34: Yolanda Broad changed "Edited KOG entry" from "<a href="/profile/70964">jethro's</a> old entry - " l’empilement des “oursins"" to ""sea urchin stack""
Proposed translations
2 hrs
Francois Boye
United States
United States
Native in French
Specializes in field
United States
An economic geek with social skills
Native in: French 
Works in: English to French, French to English, Spanish to English, and 1 more.
Related KudoZ points
:
13
French term (edited):
l’empilement des “oursins
Selected
sea urchin stack
https://en.wikipedia.org/wiki/Stack_(mathematics)
How to maximize (baking) surface area?
I like eating crust, so I am trying different baking molds to try to get the most crust per dough.
More generally, I'm interested in the reverse of this more specific question — how to maximize the surface area of a body given a constant volume. Let's ignore all the practicalities and make it a pure mathematical problem. I'm not a mathematician, so I don't even know how to try to solve it. Intuitively I came up with the following body, but I have no way of verifying its optimality: imagine a sea urchin with infinitely many infinitesimal spikes that are not touching, all anchored to an infinitesimal blob in the center. It is less and less dense as you progress from the center, so some branching could improve it.
So, what is the optimal body, given no other constraints? Please exclude Gabriel's Horn if possible; no infinite dimensions unless they fit into an oven, I mean, a finite space.
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Note added at 2 hrs (2018-02-26 23:40:45 GMT)
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https://math.stackexchange.com/questions/610393/how-to-maxim...
How to maximize (baking) surface area?
I like eating crust, so I am trying different baking molds to try to get the most crust per dough.
More generally, I'm interested in the reverse of this more specific question — how to maximize the surface area of a body given a constant volume. Let's ignore all the practicalities and make it a pure mathematical problem. I'm not a mathematician, so I don't even know how to try to solve it. Intuitively I came up with the following body, but I have no way of verifying its optimality: imagine a sea urchin with infinitely many infinitesimal spikes that are not touching, all anchored to an infinitesimal blob in the center. It is less and less dense as you progress from the center, so some branching could improve it.
So, what is the optimal body, given no other constraints? Please exclude Gabriel's Horn if possible; no infinite dimensions unless they fit into an oven, I mean, a finite space.
--------------------------------------------------
Note added at 2 hrs (2018-02-26 23:40:45 GMT)
--------------------------------------------------
https://math.stackexchange.com/questions/610393/how-to-maxim...
4 KudoZ points awarded for this answer.
Comment: "Thanks very much for your help"
Reference comments
1 hr
Nathalie Stewart
France
France
Native in French
&
English
France
Medical and Legal translations
Native in: English 
, French
Works in: English to French, French to English, Russian to English, and 1 more.
Reference:
Of sea urchins, sphere packing, crystallography, and architectural design
Just some ideas... by no means a solution, but possibly some directions you might want to follow.
https://fr.wikipedia.org/wiki/Empilement_compact
https://en.wikipedia.org/wiki/Sphere_packing
https://www.afc.asso.fr/32-aicr2014/cristallo-explications
La cristallographie est irremplaçable pour l’étude de toutes sortes de matériaux, qu’ils soient idéalement organisés (cristaux parfaits), partiellement organisés (polymères), cristallisés artificiellement (cristaux de protéines) ou peu organisés (liquides, verres). Elle est aussi à la base de l’élaboration de la plupart des nouveaux matériaux, des cellules photovoltaïques aux composites de l’automobile ou de l’aéronautique.
...Analyser des matériaux biologiques aux propriétés remarquables (fil de toile d’araignée, piquants d’oursin, bois...) pour les reproduire artificiellement...
https://pubs.acs.org/doi/abs/10.1021/cm0603809
Urchin-like nanostructures consisting of high-density spherical nanotube radial arrays...
https://www.witpress.com/Secure/elibrary/papers/DN04/DN04001...
Structure optimization in the shell structure of a sea urchin.
www.itke.uni-stuttgart.de/download.php?id=738
The shell of the sea urchin (Fig. 5) consists of a modular system of polygonal plates, which are linked together at the edges by finger-like calcite protrusions [5]. Shell action is very similar to plate action, as a finely faceted plate polyhedron is nothing but a slightly discontinuous shell which is stabilized by shear forces acting along the lines of connection [4]. High load bearing capacity is thus achieved by the particular geometric arrangement of the plates and their joining system. Therefore, the sea urchin serves as a perfect model for shells made of prefabricated elements.
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Note added at 1 hr (2018-02-26 22:01:12 GMT)
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See also "Kepler's Urchin" (small stellated dodecahedron) and "Kepler conjecture" ("no arrangement of equally sized spheres filling space has a greater average density than that of the cubic close packing (face-centered cubic) and hexagonal close packing arrangements")
https://fr.wikipedia.org/wiki/Empilement_compact
https://en.wikipedia.org/wiki/Sphere_packing
https://www.afc.asso.fr/32-aicr2014/cristallo-explications
La cristallographie est irremplaçable pour l’étude de toutes sortes de matériaux, qu’ils soient idéalement organisés (cristaux parfaits), partiellement organisés (polymères), cristallisés artificiellement (cristaux de protéines) ou peu organisés (liquides, verres). Elle est aussi à la base de l’élaboration de la plupart des nouveaux matériaux, des cellules photovoltaïques aux composites de l’automobile ou de l’aéronautique.
...Analyser des matériaux biologiques aux propriétés remarquables (fil de toile d’araignée, piquants d’oursin, bois...) pour les reproduire artificiellement...
https://pubs.acs.org/doi/abs/10.1021/cm0603809
Urchin-like nanostructures consisting of high-density spherical nanotube radial arrays...
https://www.witpress.com/Secure/elibrary/papers/DN04/DN04001...
Structure optimization in the shell structure of a sea urchin.
www.itke.uni-stuttgart.de/download.php?id=738
The shell of the sea urchin (Fig. 5) consists of a modular system of polygonal plates, which are linked together at the edges by finger-like calcite protrusions [5]. Shell action is very similar to plate action, as a finely faceted plate polyhedron is nothing but a slightly discontinuous shell which is stabilized by shear forces acting along the lines of connection [4]. High load bearing capacity is thus achieved by the particular geometric arrangement of the plates and their joining system. Therefore, the sea urchin serves as a perfect model for shells made of prefabricated elements.
--------------------------------------------------
Note added at 1 hr (2018-02-26 22:01:12 GMT)
--------------------------------------------------
See also "Kepler's Urchin" (small stellated dodecahedron) and "Kepler conjecture" ("no arrangement of equally sized spheres filling space has a greater average density than that of the cubic close packing (face-centered cubic) and hexagonal close packing arrangements")
Peer comments on this reference comment:
| agree |
Charles Davis
: I think it might be a way of referring to Kepler's conjecture. It must surely have something to do with Kepler, since "empilement" is packing and "urchin", as you say, was what K called a star polyhedron.
47 mins
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Thank you! It's possible... Hard to tell without more context. The subject line also mentions "architecture".
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Discussion
Un oursin est une multitude de fibres qui collent ensemble durant l’intégration des fibres et le malaxage. Les oursins peuvent bloquer la pompe à béton et former des intrus mal compactés dans le béton durci, susceptibles de fissuration.