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Wyszukujesz frazę "critical aspect" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Relate before calculate: Students’ ways of experiencing relationships between quantities
Autorzy:
Tuominen, Jane
Andersson, Charlotta
Bjorklund Boistrup, Lisa
Eriksson, Inger
Powiązania:
https://bibliotekanauki.pl/articles/749306.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
general mathematical structures
relationships
part-whole
additive structures
quantities
phenomenography
ways of experiencing
critical aspect
Opis:
The aim of this article is to contribute with findings concerning students’ ways of experiencing general mathematical structures and, in particular, relationships in additive structures.When students discern relationships in additive structures, it may lead to positive consequences for students’ future ability to perform calculations in addition and subtraction tasks. In the study, semi-structured interviews were conducted with students in grades 3, 8, and 9. An illustration showing a set of different quantities was the starting point during the interviews, together with an opening question regarding how the diverse quantities could be equalised. After the students’ discussions, they were asked if this could be described mathematically using written symbols. The students’ expressions concerning the phenomenon “relationships between quantities” were analyzed using phenomenography as an analytical tool. According to phenomenography, there are a limited number of ways in which a phenomenon can be experienced. Further, it is not about exploring how many individuals hold a specific experience that is of interest. In the case of this article, it is about capturing qualitatively different ways of experiencing the phenomenon relationships between quantities. Despite no specific numbers being presented, many students attributed specific numbers and values when expressing relationships between quantities. The students expressed general mathematical structures only to a limited extent and, in those cases, mostly only after encouragement from the interviewer. Following the phenomenographical analysis, the students’ ways of experiencing “relationships between quantities” are: as something that has to be calculated, or as something that has to be related. The first of these was most common in all grades. In this study, one critical aspect was identified, namely, that quantities are related to each other, additively. Instead of introducing mathematics with a focus on answer-oriented tasks, it is essential to introduce mathematics based on general structures such as additive structures. Even if the students are not familiar with such a mathematical “culture”, it is worth it. This was confirmed in our study.
Źródło:
Didactica Mathematicae; 2018, 40; 5-33
0208-8916
2353-0960
Pojawia się w:
Didactica Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical nature of a single walled carbon nanotube using Legendre’s polynomials
Autorzy:
Tiwari, P.
Nagar, P.
Powiązania:
https://bibliotekanauki.pl/articles/279475.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Euler-Bernoulli’s beam theory
nonlocal elasticity theory
Legendre’s polynomial
aspect ratio
critical buckling load
Winkler and Pasternak elastic constants
Opis:
This paper is concerned with the mechanical response of a single-walled carbon nanotube. Euler-Bernoulli’s beam theory and Hamilton’s principle are employed to derive the set of governing differential equations. An efficient variational method is used to determine the solution of the problem and Legendre’s polynomials are used to define basis functions. Significance of using these polynomials is their orthonormal property as these shape functions convert mass and stiffness matrices either to zero or one. The impact of various parameters such as length, temperature and elastic medium on the buckling load is observed and the results are furnished in a uniform manner. The degree of accuracy of the obtained results is verified with the available literature, hence illustrates the validity of the applied method. Current findings show the usage of nanostructures in vast range of engineering applications. It is worth mentioning that completely new results are obtained that are in validation with the existing results reported in literature.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 4; 1153-1162
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the critical velocity of a straight wing with a high aspect ratio
Autorzy:
Thanh, Le Thi
Powiązania:
https://bibliotekanauki.pl/articles/45423968.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
prędkość krytyczna
aerodynamika
pręt
thin rod
divergence
linear aerodynamics
straight wing
high aspect ratio
critical velocity
Opis:
An aerodynamic problem on an air flow around a large aspect ratio rectangular wing is investigated in this study. According to the theory of Vlasov, the wing is considered to be a thin rod. External loads are assumed to be proportional to the airfoil angle of attack related to the dimensionless coefficient of the lift and the pitching moment coefficient. These coefficients depend on the airfoil parameters and the Mach number M and are determined by experimental measurements for subsonic and supersonic velocities. In this case, to define the unstable cases of the wing, one bases on the Lyapunov stability theory. Equations of bending and torsional free vibrations have resulted. Based on the analysis of natural frequencies (eigenfrequencies), it is possible to determine the changing positions of the real part and the imaginary part of the characteristic equation solution. These positions can cause instabilities for the wing such as torsional divergence and flutter.
Źródło:
International Journal of Applied Mechanics and Engineering; 2023, 28, 1; 105-117
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Liquid bridge in slit pore geometry
Autorzy:
Hu, Junhui
Wu, Mengjiao
Bai, Kezhao
Yang, Li
Powiązania:
https://bibliotekanauki.pl/articles/1839700.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
liquid bridge
slit, pinning angle
critical aspect ratio
saddle shape
Opis:
In this work, the morphology of a liquid bridge in a slit pore geometry was investigated as a function of both the bridge height and aspect ratio (height/width). The end contour interface of the liquid bridge was modeled by using a saddle shape, and the liquid-air interface was described via an arc of a circle. By employing the free energy approach, a simple formula was obtained to predict variation of the pinning angle as a function of the distance between the slits. The pinning angle depended on the liquid volume and on both the wetting properties and the geometry of the system (height and width). The critical aspect ratio at which the liquid bridge meniscus transitioned from concave to convex was determined. The calculations were in good agreement with the experimental data. The morphology of the liquid bridges in a slit pore geometry can be used in various fields such as the packaging of electronic and micro-electromechanical systems.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 1; 135-142
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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