On focal curves of null Cartan curves

The focal curve, which is determined as the locus of centers of osculating pseudo-spheres of a null Cartan curve, is investigated in Minkowski (n+2)-space Mn+2. Moreover, a curve called acceleration focal curve of a null Cartan curve is introduced by using a new family of functions.No sponsorhttps://doi.org/10.3906/mat-1604-7

On conformal curves in 2-dimensional de sitter space

In this paper, we examine the pseudo-spherical curves, which are equivalent to each other under the conformal maps preserving a fixed point in the de Sitter 2-space, by using the Clifford algebra Cl 2,1. Also, we find the parametric equations of de Sitter loxodromes.No sponso

Similar and self-similar curves in minkowski n-space

In this paper, we investigate the similarity transformations in the Minkowski n-space. We study the geometric invariants of nonnull curves under the similarity transformations. Besides, we extend the fundamental theorem for a non-null curve according to a similarity motion of En1. We determine the parametrizations of non-null self-similar curves in En1. .No sponso

Some results on p-shape curvatures of non-lightlike space curves

In this paper, we obtain some findings for a non-null curve parameterized by spherical arc length. We investigate the relationship between a non-null curve with p-shape curvatures and pseudospherical curves on S21 and H2(−1). We introduce the concept of similar helix in Minkowski 3-space E31. Besides, we explicitly determine the parametrizations of all non-lightlike self-similar curves by using the pseudo-spherical curves in E31.No sponso

On the Braids for 8 10 Knot

Bu makale 8 10 düğümü ve onun örgüsü ile ilgilidir. Düğüm teorisinde önemli kavramlardan birisi olan örgü kavramını kullanarak 8 10 düğümünün örgüsünün Artin ve Garside temsilini elde edeceğiz. Daha sonra pozitiflik kavramı irdelenecektir.This paper is concerned with 810 knots and its braids. The braids structure is very important role in Knots Theory. In view of this structure, we obtained braids for that knot and we will give the representations of Artin and we examine Garside Word problem. And then we will examine the positivity structure for these knots

On the Braids for 8 10 Knot

Bu makale 8 10 düğümü ve onun örgüsü ile ilgilidir. Düğüm teorisinde önemli kavramlardan birisi olan örgü kavramını kullanarak 8 10 düğümünün örgüsünün Artin ve Garside temsilini elde edeceğiz. Daha sonra pozitiflik kavramı irdelenecektir.This paper is concerned with 810 knots and its braids. The braids structure is very important role in Knots Theory. In view of this structure, we obtained braids for that knot and we will give the representations of Artin and we examine Garside Word problem. And then we will examine the positivity structure for these knots

An alternative approach to determination of Covid‑19 personal risk index by using fuzzy logic

COVID-19 disease is an outbreak that seriously affected the whole world, occurred in December 2019, and thus was declared a global epidemic by WHO (World Health Organization). To reduce the impact of the epidemic on humans, it is important to detect the symptoms of the disease in a timely and accurate manner. Recently, several new variants of COVID-19 have been identified in the United Kingdom (UK), South Africa, Brazil and India, and preliminary findings have been suggested that these mutations increase the transmissibility of the virus. Therefore, the aim of this study is to construct a support system based on fuzzy logic for experts to help detect of COVID-19 infection risk in a timely and accurate manner and to get a numerical output on symptoms of the virus from every person. The decision support system consists of three different sub and one main Mamdani type fuzzy inference systems (FIS). Subsystems are Common- Serious symptoms (First), Rare Symptoms (Second) and Personal Information (Third). The first FIS has five inputs, fever-time, cough-time, fatigue-time, shortness of breath and chest pain/dysfunction; the second FIS has four inputs, Loss of Taste/Smell, Body Aches, Conjuctivitis, and Nausea/Vomiting/Diarrhea; and the third FIS has three inputs, Age, Smoke, and Comorbidities. Then, we obtain personal risk index of individual by combining the outputs of these subsystems in a final FIS. The results can be used by health professionals and epidemiologists to make inferences about public health. Numerical output can also be useful for self-control of an individual.No sponso

On the eigenvalues and eigenvectors of a lorentzian rotation matrix by using split quaternions

In this paper, we examine eigenvalue problem of a rotation matrix in Minkowski 3 space by using split quaternions. We express the eigenvalues and the eigenvectors of a rotation matrix in term of the coefficients of the corresponding unit timelike split quaternion. We give the characterizations of eigenvalues (complex or real) of a rotation matrix in Minkowski 3 space according to only first component of the corresponding quaternion. Moreover, we find that the casual characters of rotation axis depend only on first component of the corresponding quaternion. Finally, we give the way to generate an orthogonal basis for 31 by using eigenvectors of a rotation matrix.No sponso

Some mechanical properties and decay resistance of wood impregnated with environmentally-friendly borates

This study was made to determine some mechanical properties such as compression strength parallel to grain, modulus of rupture, and decay resistance of wood treated with some environmentally-friendly borates. Sodium tetrafluoroborate (SFB), ammonium tetrafluoroborate, (AFB), and ammonium pentaborate octahydrate (APB) were used as borates. Wood specimens were prepared from Oriental beech (Fagus orientalis L) and Scots pine (Pin us sylvestris L.). Before tests, wood specimens were impregnated with aqueous solutions (0.25%, 0.50%, 1.50%, and 3.00%) of borates according to ASTM D 1413-76. Results showed that compression strength parallel to grain (CSPG) and modulus of rupture (MOR) of wood specimens treated with borates were lower compared to untreated control specimen. In general, our results showed that the higher concentration levels of borates, the lower mechanical properties of wood resulted. Borate treated wood showed considerable resistance to the decay fungus compared to that of untreated control specimen. (C) 2010 Elsevier Ltd. All rights reserved