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Author |
Caratelli, D.; Gielis, J.; Tavkhelidze, I.; Ricci, P.E. |
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Title |
Fourier-Hankel solution of the Robin problem for the Helmholtz equation in supershaped annular domains |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Boundary value problems |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
253 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
The Robin problem for the Helmholtz equation in normal-polar annuli is addressed by using a suitable Fourier-Hankel series technique. Attention is in particular focused on the wide class of domains whose boundaries are defined by the so-called superformula introduced by Gielis. A dedicated numerical procedure based on the computer algebra system Mathematica© is developed in order to validate the proposed methodology. In this way, highly accurate approximations of the solution, featuring properties similar to the classical ones, are obtained. |
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Wos |
000340237600004 |
Publication Date |
2013-11-22 |
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ISSN |
1687-2762; 1687-2770 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Open Access |
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no |
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Call Number |
UA @ admin @ c:irua:111558 |
Serial |
7981 |
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Permanent link to this record |
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Author |
Caratelli, D.; Gielis, J.; Tavkhelidze, I.; Ricci, P.E. |
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Title |
Spherical harmonic solution of the Robin problem for the Helmholtz equation in a supershaped shell |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Applied mathematics |
Abbreviated Journal |
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Volume |
4 |
Issue |
1a |
Pages |
263-270 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
The Robin problem for the Helmholtz equation in normal-polar shells is addressed by using a suitable spherical harmonic expansion technique. Attention is in particular focused on the wide class of domains whose boundaries are defined by a generalized version of the so-called superformula introduced by Gielis. A dedicated numerical procedure based on the computer algebra system Mathematica? is developed in order to validate the proposed methodology. In this way, highly accurate approximations of the solution, featuring properties similar to the classical ones, are obtained. |
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Publication Date |
2013-01-30 |
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Series Volume |
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Edition |
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ISSN |
2152-7385 |
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Additional Links |
UA library record |
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no |
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Call Number |
UA @ admin @ c:irua:107177 |
Serial |
8576 |
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Author |
Li, Y.; Niklas, K.J.; Gielis, J.; Niinemets, Ü.; Schrader, J.; Wang, R.; Shi, P. |
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Title |
An elliptical blade is not a true ellipse, but a superellipse : evidence from two Michelia species |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
Journal of forestry research |
Abbreviated Journal |
J Forestry Res |
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Volume |
33 |
Issue |
4 |
Pages |
1341-1348 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
The shape of leaf laminae exhibits considerable diversity and complexity that reflects adaptations to environmental factors such as ambient light and precipitation as well as phyletic legacy. Many leaves appear to be elliptical which may represent a ‘default’ developmental condition. However, whether their geometry truly conforms to the ellipse equation (EE), i.e., (x/a)2 + (y/b)2 = 1, remains conjectural. One alternative is described by the superellipse equation (SE), a generalized version of EE, i.e., |x/a|n +|y/b|n = 1. To test the efficacy of EE versus SE to describe leaf geometry, the leaf shapes of two Michelia species (i.e., M. cavaleriei var. platypetala, and M. maudiae), were investigated using 60 leaves from each species. Analysis shows that the majority of leaves (118 out of 120) had adjusted root-mean-square errors of < 0.05 for the nonlinear fitting of SE to leaf geometry, i.e., the mean absolute deviation from the polar point to leaf marginal points was smaller than 5% of the radius of a hypothesized circle with its area equaling leaf area. The estimates of n for the two species were ˂ 2, indicating that all sampled leaves conformed to SE and not to EE. This study confirms the existence of SE in leaves, linking this to its potential functional advantages, particularly the possible influence of leaf shape on hydraulic conductance. |
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Wos |
000695118600001 |
Publication Date |
2021-09-12 |
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Series Issue |
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Edition |
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ISSN |
1007-662x; 1993-0607 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3 |
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Call Number |
UA @ admin @ c:irua:180967 |
Serial |
7152 |
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Author |
Lin, S.; Zhang, L.; Reddy, G.V.P.; Hui, C.; Gielis, J.; Ding, Y.; Shi, P. |
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Title |
A geometrical model for testing bilateral symmetry of bamboo leaf with a simplified Gielis equation |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
Ecology and evolution |
Abbreviated Journal |
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Volume |
6 |
Issue |
19 |
Pages |
6798-6806 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
The size and shape of plant leaves change with growth, and an accurate description of leaf shape is crucial for describing plant morphogenesis and development. Bilateral symmetry, which has been widely observed but poorly examined, occurs in both dicot and monocot leaves, including all nominated bamboo species (approximately 1,300 species), of which at least 500 are found in China. Although there are apparent differences in leaf size among bamboo species due to genetic and environmental profiles, bamboo leaves have bilateral symmetry with parallel venation and appear similar across species. Here, we investigate whether the shape of bamboo leaves can be accurately described by a simplified Gielis equation, which consists of only two parameters (leaf length and shape) and produces a perfect bilateral shape. To test the applicability of this equation and the occurrence of bilateral symmetry, we first measured the leaf length of 42 bamboo species, examining >500 leaves per species. We then scanned 30 leaves per species that had approximately the same length as the median leaf length for that species. The leaf-shape data from scanned profiles were fitted to the simplified Gielis equation. Results confirmed that the equation fits the leaf-shape data extremely well, with the coefficients of determination being 0.995 on average. We further demonstrated the bilateral symmetry of bamboo leaves, with a clearly defined leaf-shape parameter of all 42 bamboo species investigated ranging from 0.02 to 0.1. This results in a simple and reliable tool for precise determination of bamboo species, with applications in forestry, ecology, and taxonomy. |
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Wos |
000385626100003 |
Publication Date |
2016-09-02 |
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Edition |
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ISSN |
2045-7758 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
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Open Access |
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no |
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Call Number |
UA @ admin @ c:irua:144547 |
Serial |
7998 |
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Permanent link to this record |
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Author |
Huang, W.; Su, X.; Ratkowsky, D.A.; Niklas, K.J.; Gielis, J.; Shi, P. |
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Title |
The scaling relationships of leaf biomass vs. leaf surface area of 12 bamboo species |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Global ecology and conservation |
Abbreviated Journal |
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Volume |
20 |
Issue |
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Pages |
e00793 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
There is convincing evidence for a scaling relationship between leaf dry weight (DW) and leaf surface area (A) for broad-leaved plants, and most estimates of the scaling exponent of DW vs. A are greater than unity. However, the scaling relationship of leaf fresh weight (FW) vs. A has been largely neglected. In the present study, we examined whether there is a statistically strong scaling relationship between FW and A and compared the goodness of fit to that of DW vs. A. Between 250 and 520 leaves from each of 12 bamboo species within 2 genera (Phyllostachys and Pleioblastus) were investigated. The reduced major axis regression protocols were used to determine scaling relationships. The fit for the linearized scaling relationship of FW vs. A was compared with that of DW vs. A using the coefficient of determination (i.e., r2). A stronger scaling relationship between FW and A than that between DW and A was observed for each of the 12 bamboo species investigated. Among the 12 species examined, five had significantly smaller scaling exponents of FW vs. A compared to those of DW vs. A; only one species had a scaling exponent of FW vs. A greater than that of DW vs. A. No significant difference between the two scaling exponents was observed for the remaining 6 species. Researchers conducting future studies might be well advised to consider the influence of leaf fresh weight when exploring the scaling relationships of foliar biomass allocation patterns. |
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Wos |
000498226800095 |
Publication Date |
2019-09-19 |
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Edition |
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ISSN |
2351-9894; 2351-9894 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
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Open Access |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:162954 |
Serial |
8497 |
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Author |
Chapman, D.; Gielis, J. |
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Title |
Gielis transformations for the audiovisual geometry database |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Symmetry : culture and science |
Abbreviated Journal |
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Volume |
32 |
Issue |
2 |
Pages |
177-180 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
This publication introduces the audiovisual geometry database with Gielis transformations as initial records for a prototype of the database. A concise overview is given of the rationale behind the database and studying wave phenomena with Gielis transformations. First results on a form of timbral polyphony observed in Gielis curves and future work are briefly discussed. |
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Publication Date |
2021-07-02 |
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Edition |
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ISSN |
0865-4824 |
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Additional Links |
UA library record |
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Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:180965 |
Serial |
8004 |
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Permanent link to this record |
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Author |
Martínez-Dueñas, E.J.R.; de Jong van Coevorden, C.M.; Stukach, O.V.; Panokin, N.V.; Gielis, J.; Caratelli, D. |
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Title |
Electromagnetic modeling and design of a novel class of complementary split‐ring resonators |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
International journal of RF and microwave computer-aided engineering |
Abbreviated Journal |
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Volume |
29 |
Issue |
4 |
Pages |
e21582 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
This research study reports the assessment of complementary split ring resonators based on Gielis transformation as basic elements for the design of high‐performance microwave components in printed technology. From the electromagnetic simulation of said structures, suitable equivalent circuit models are extracted and analyzed. Physical prototypes are fabricated and tested for design validation. The obtained results confirm that the adoption of supershaped geometries enables the synthesis of very compact scalable microwave filters. |
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Wos |
000460308500020 |
Publication Date |
2018-11-19 |
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Edition |
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ISSN |
1096-4290 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Open Access |
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Notes |
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no |
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Call Number |
UA @ admin @ c:irua:155021 |
Serial |
7867 |
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Permanent link to this record |
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Author |
Gielis, J.; Natalini, P.; Ricci, P.E. |
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Title |
A note about generalized forms of the Gielis formula |
Type |
H1 Book chapter |
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Year |
2017 |
Publication |
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Abbreviated Journal |
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Volume |
2 |
Issue |
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Pages |
107-116
T2 - Modeling in mathematics : proceedings |
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Keywords |
H1 Book chapter; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
We generalize the Gielis Superformula by extending the R. Chacon approach, but avoiding the use of Jacobi elliptic functions. The obtained results are extended to the three-dimensional case. Several new shapes are derived by using the computer algebra system Mathematica(C). |
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Wos |
000442076400008 |
Publication Date |
2017-04-20 |
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ISBN |
978-94-6239-260-1; 978-94-6239-261-8; 2543-0300; 978-94-6239-260-1 |
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:144550 |
Serial |
8318 |
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Permanent link to this record |