curved surfaces
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Author(s):  
Bahar Kuloğlu ◽  
Engin Özkan

In this paper, an expansion of the classical hyperbolic functions is presented and studied. Also, many features of the [Formula: see text]-Jacobsthal hyperbolic functions are given. Finally, we introduced some graph and curved surfaces related to the [Formula: see text]-Jacobsthal hyperbolic functions.


2022 ◽  
Vol 12 (2) ◽  
pp. 550
Author(s):  
Yiheng Song ◽  
Ziying Wang ◽  
Jie Chen ◽  
Jinxiang Chen

Curved surfaces can give plates a unique aesthetic effect and physical advantages in acoustics and optics. Assembling such curved plates can greatly improve the image of buildings and enrich their functions. It is thus not surprising to notice that their wide applications in designed or completed buildings in China have become a trend. Thus, this study offers a comprehensive summary of the application progress of curved plates in the architectural field from three aspects: image expression, acoustic characteristics, and optical characteristics. On this basis, future directions are proposed. The main findings or suggestions are as follows: (1) climate harshness has increased recently, and the safety of structures and materials and the coupling effect of the two must be fully considered when designing the shapes of curved surface buildings; (2) research on the mechanism and numerical calculation of curved diffuser systems with different sizes and curvatures needs to be further developed; and (3) experimental studies of various and complex curved plates and different conditions to explore their optimal reflectivity, transmittance, absorptivity, and other optical properties will be an important development direction.


Author(s):  
Rita Nagy-Kondor ◽  
Saeed Esmailnia

AbstractSpatial ability contributes to performance in science, technology, engineering and mathematics (STEM). Spatial skills and creativity are required for engineering studies. Low spatial abilities can lead to the dropout of students’ university studies. In this study the Spatial Ability Extra Tasks (SAET) was developed to evaluate engineering students’ complex spatial abilities. A total of 93 first-year engineering students from University of Debrecen Faculty of Engineering and Sharif University of Technology in Tehran participated, with regard to final mathematical exam and their gender, participated in the study. SAET measures parts of spatial abilities: mental cutting and mental rotation and creativity. Analysis of the findings suggested that SAET is valid and reliable. The separate tests results have been statistically evaluated and conclusions were formulated. We used Structural Equation Modeling analysis. We separate two types of tasks by SAET which are Polyhedron part and Curved Surface part. According to obtained data, accomplished the results: students of University of Debrecen are more successful at Curved Surfaces. In addition students of Sharif University are more successful at Polyhedrons. The square cross section was found by most student in both countries in Polyhedrons. It is remarkable that first-year engineering students of Tehran are more successful at Polyhedrons by pentagon, hexagon and parallelogram solution; and students of Debrecen are more successful by square and rectangle solution. Students of Debrecen are more successful at Curved Surfaces to find circle solution of cylinder, cone and sphere; students of Tehran are more successful by finding parabola solution of cone.


2022 ◽  
Vol 355 ◽  
pp. 01001
Author(s):  
Pan Jin ◽  
Jin Feng

Suppose that curved compression surface of inlet consists of segments. Two curved surfaces formed by equal compression angles of the micro-element segments and a slight increase in the compression angle of the micro-element segments are designed respectively. The numerical simulation method is used to compare the performance of two curved surfaces with the reference three-wedge compression surface. Select NASA classic test data, in order to determine the turbulence model and calculation method chosen by the numerical simulation Fluent software. The results show: the configuration of the segment compression angle deeply affects compression efficiency of the curved surface compression system. Pressure gradient distribution on the compression surface with constant compression angles segments is nearly constant along the incoming flow direction, and the curved compression surface easily resist the separation of the boundary layer compared to three-wedges compression surface. The approximate calculation method of the bending shock profile is given.


2021 ◽  
pp. 101551
Author(s):  
Wei Wang ◽  
Yi Sun ◽  
Linghui He ◽  
Yong Ni
Keyword(s):  

2021 ◽  
pp. 30-38
Author(s):  
A. Efremov ◽  
T. Vereschagina ◽  
Nina Kadykova ◽  
Vyacheslav Rustamyan

Tiling of three-dimensional space is a very interesting and not yet fully explored type of tiling. Tiling by convex polyhedra has been partially investigated, for example, works [1, 15, 20] are devoted to tiling by various tetrahedra, once tiling realized by Platonic, Archimedean and Catalan bodies. The use of tiling begins from ancient times, on the plane with the creation of parquet floors and ornaments, in space - with the construction of houses, but even now new and new areas of applications of tiling are opening up, for example, a recent cycle of work on the use of tiling for packaging information [17]. Until now, tiling in space has been considered almost always by faceted bodies. Bodies bounded by compartments of curved surfaces are poorly considered and by themselves, one can recall the osohedra [14], dihedra, oloids, biconuses, sphericon [21], the Steinmetz figure [22], quasipolyhedra bounded by compartments of hyperbolic paraboloids described in [3] the astroid ellipsoid and hyperbolic tetrahedra, cubes, octahedra mentioned in [6], and tiling bodies with bounded curved surfaces was practically not considered, except for the infinite three-dimensional Schwartz surfaces, but they were also considered as surfaces, not as bodies., although, of course, in each such surface, you can select an elementary cell and fill it with a body, resulting in a geometric cell. With this work, we tried to eliminate this gap and described approaches to identifying geometric cells bounded by compartments of curved surfaces. The concept of tightly packed frameworks is formulated and an approach for their identification are described. A graphical algorithm for identifying polyhedra and quasipolyhedra - geometric cells are described.


2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Patrick Jagerhofer ◽  
Jakob Woisetschläger ◽  
Gerhard Erlacher ◽  
Emil Göttlich

Abstract A measurement technique for recording convective heat transfer coefficient and adiabatic film cooling effectiveness in demanding environments with highly curved surfaces and limited optical access, such as turbomachinery, is presented. Thermography and tailor-made flexible heating foils are used in conjunction with a novel multistep calibration and data reduction method. This method compensates for sensor drift, angle dependence of surface emissivity and window transmissivity, heat flux inhomogeneity, and conductive losses. The 2D infrared images are mapped onto the 3D curved surfaces and overlapped, creating surface maps of heat transfer coefficient and film cooling effectiveness covering areas significantly larger than the window size. The measurement technique’s capability is demonstrated in a sector-cascade test rig of a turbine center frame (TCF), an inherent component of modern two-spool turbofan engines. The horseshoe vortices were found to play a major role for the thermal integrity of turbine center frames, as they lead to a local increase in heat transfer, and at the same instance, to a reduction of film cooling effectiveness. It was also found that the horseshoe vortices lift off from the curved surface at 50% hub length, resulting in a pair of counter-rotating vortices. The measurement technique was validated by comparing the data against flat plate correlations and also by the linear relation between temperature difference and heat flux. This study is complemented with an extensive error and uncertainty analysis. Article highlights This paper presents an accurate measurement technique for heat transfer and film cooling on 3D curved surfaces with limited optical access using flexible tailor-made heating foils, infrared thermography and a high-fidelity multistep calibration process. Graphical abstract


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