Properties of Cyclide Dyupen and Their Application. Part 2

2015 ◽  
Vol 3 (2) ◽  
pp. 9-22 ◽  
Author(s):  
Сальков ◽  
Nikolay Sal'kov

In the first part of this paper has discussed about the basic properties of cyclide Dupin, and has gave some examples of their applications: three ways of solving the problem of Apollonius exclusively by means of compass and ruler, using identified properties cyclide Dupin, that is, given a classical solution of the problem. In the second of part of the work continued consideration of the properties of cyclide Dupin. Proposed and proved the possibility ask cyclide Dupin arbitrary ellipse as the center line of the forming a plurality of spheres and a sphere with the center belong - ing to the ellipse. Proved the adequacy of this information is used to build the cyclide Dupin. Geometrically proved that the focal line of cychlid are not that other, as curves of the second order. Given the graphical representation of the focal lines of cychlid. Shown polyconic compliance focal lines of cichlid of Dupin, which is considered in all four cases. The proposed formation of the hyperbolic surfaces of the fourth order with one or two primary curves of the second order, in this case ellipses. Apply sofocus this ellipse the hyperbola. Although the primary focus of the ellipse lying in the plane of the hoe, with the center coinciding with the origin of coordinates, is stationary, and the coordinate system rotates around the z axis. Then the points of intersection of the rotating coordinates x and y with a fixed ellipse specify new values for the major and minor axis of the ellipse with resultant changes in the form defocuses of the hyperbola. Although this modeling is not directly connected with Cychlidae Dupin, but clearly follows from the properties of its focal curves – curves of the second order. Withdrawn Equations of the surface and its throat.




1995 ◽  
Vol 90 (2-3) ◽  
pp. 167-187 ◽  
Author(s):  
Jean-Paul Malrieu ◽  
Jean-Louis Heully ◽  
Andr�i Zaitsevskii


Author(s):  
V. I. Korzyuk ◽  
S. N. Naumavets ◽  
V. A. Sevastyuk

This paper considers the mixed problem for a one-dimensional wave equation with second-order derivatives at boundary conditions. Using the method of characteristics, a classical solution to this problem is found in analytical form. Its uniqueness is proved under the relevant compatibility conditions.



2020 ◽  
Vol 1 ◽  
pp. 53-60
Author(s):  
Kristina Kilova ◽  
Desislava Bakova ◽  
Antonia Yaneva ◽  
Vanina Mihaylova

Background: The increasing use of mobile phones has offered an opportunity to improve the quality of health services, secure the accessibility of healthcare systems for a larger population and support patients in effective management of their health/chronic conditions. Main Goal: The primary focus of the study in hand is to explore the different attitudes towards the use of mHealth in Bulgaria and to examine the extensive use of mobile health applications for the supervision, prevention and containment of various socially relevant diseases, including the promotion of healthy lifestyles. Materials and methods: An online survey was conducted in the period between July 2019 and February 2020. Amongst the 976 people that were interviewed, 591 (60.6%) were females and 385 (39.4%) were males. The mean age of the respondents was 43.25 ± 0.755. A unique questionnaire was prepared for the collection of information regarding the usage of mobile health applications. Statistical analyses were carried out with the help of IBM SPSS Statistics, version 23. MS Excel 2016 was used for the graphical representation of the results. Results: 89% of the participants possessed a mobile phone and an approximate 84% of them used mHealth applications. Besides this, the results suggested a considerable statistical difference in the respondents’ attitudes, in terms of their gender, where the deviation was in favour of female respondents. Additionally, findings revealed another statistical difference on the basis of their age and level of education. Furthermore, a huge majority claimed that they generally used these types of applications for monitoring their blood pressure or pulse. Conclusion: The outcome of the study was that a significant number of respondents were already using or tended to use smartphones and various applications, including health ones. We expect that the results of this study will provide evidence of the essentiality of mobile health applications to be developed in Bulgaria. This is crucial for patients as this technology has the potential to open up several new possibilities for treatments and observations of diverse socially significant diseases.





2008 ◽  
Vol 102 (2) ◽  
pp. 107-111
Author(s):  
Gail M. Anderson

One of NCTM's ten standards for school mathematics is Representation: “Representations [such as diagrams, graphs, and symbols] should be treated as essential elements in supporting students' understanding of mathematical concepts and relationships; in communicating mathematical approaches, arguments, and understandings to one's self and to others; in recognizing connections among related mathematical concepts; and in applying mathematics to realistic problem situations through modeling” (NCTM 2000, p. 67). In my experience, one of the biggest issues students struggle with is the connection between equations and their graphs (referred to as the “Cartesian connection” in an interesting study by Knuth [2000]). Unfortunately, although students are becoming proficient in using algebraic and graphical representations independently, they often do not make the connection between the two representational formats (Knuth 2000; NCTM 2000; Van Dyke and White 2004). In this article, I will explore the history of the graphical representation of functions and curves, specifically, the development of the Cartesian coordinate system as the most common frame for this graphical representation.



1990 ◽  
Vol 112 (1) ◽  
pp. 52-59 ◽  
Author(s):  
D. Vijayaraghavan ◽  
T. G. Keith

An existing cavitation algorithm (a numerical procedure that automatically predicts film rupture and reformation in bearings) is modified in this paper. Second order upwinding is used to difference the shear induced flow terms in the cavitated region. A grid transformation procedure using a body fitted coordinate system and grid adaption techniques are applied to the algorithm. Four statically loaded finite journal bearing cases are analyzed. The results are compared with the results obtained using a conventional grid. The advantage of these methods is demonstrated by obtaining equal or better accuracy with a coarser grid and by the consumption of smaller amounts of computer time.



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