Ahmet Yildiz

ON Φ-RECURRENT (k, μ)-CONTACT METRIC MANIFOLDS

In this paper we prove that a -recurrent (k, )-contact metric manifold is an -Einstein manifold with constant coefficients. Next, we prove that a three-dimensional locally -recurrent (k, )-contact metric manifold is the space of constant curvature. The existence of -recurrent (k, )-manifold is proved by a non-trivial example.

A Class of Lorentzian α-Sasakian Manifolds

In this study we consider φ conformally at, φ conharmonically at, φ projectively at and φ concircularly at Lorentzian α Sasakian manifolds. In all cases, we get the manifold will be an η Einstein manifold.

Certain curvature conditions on generalized sasakian space-forms

Abstract The object of the present paper is to study certain curvature conditions on generalized Sasakian space-forms. We classify generalized Sasakian space-forms which satisfy P · P=0, P · Z˜=0, Z˜ · P=0, Z˜ · Z˜=0, where P is the projective curvature tensor and Z˜ is the concircular curvature tensor.

Characterizations of mixed quasi-Einstein manifolds

The object of the present paper is to study mixed quasi-Einstein manifolds. Some geometric properties of mixed quasi-Einstein manifolds have been studied. We also discuss M(QE)4 spacetime with spac...

Chaki type pseudo-symmetric lightlike hypersurfaces

In this paper, we investigate lightlike hypersurfaces which are Chaki type pseudo-symmetric, Chaki type pseudo-Ricci symmetric and Chaki type pseudo-projective symmetric in a semi-Euclidean space. We also give some physical interpretations of Chaki type pseudo-symmetry condition.

Toroidal Continuously Variable Transmission Systems: Terminology and Present Studies

Havacilik, robotik, makine ve otomotiv sanayi gibi bircok farkli alanlarda sabit cevrim oranli hiz donusturuculere alternatif surekli degisken aktarma (SDA) sistemlerinin kullanimi giderek yayginlasmaktadir. Ozellikle otomotiv sanayinde motorun surekli optimum devirde calismasina imkan vererek onemli yakit tasarrufu ve bunun sonucu daha dusuk emisyon degerleri, yuksek ivmelenmeye ve sessiz calismaya imkan saglamalari gibi nedenlerden dolayi son zamanlarda kullanimlari artmaktadir. SDA sistemlerinin kayisli, zincirli, bilyeli, toroidal vb. gibi bircok degisik cesitleri mevcuttur. Bu calismada elastohidrodinamik ilkelere gore calisan toroidal SDA sistemleri ele alinmis olup bunlar hakkinda son yirmi yilda onem arz eden temel calismalar gozden gecirilmistir. Incelenen literaturun daha iyi anlasilmasina katkida bulunmasi icin konuya iliskin terminolojiyle birlikte sistemlerin dinamigi ve kontrolune de yer verilmistir. Mevcut arastirma calismalarinda bazi onemli konularin eksikligine dikkat cekilmis ve gelecekteki muhtemel calismalara isaret edilmistir. Yazarlarin tespit edebildigi kadariyla bu calisma, toroidal SDA sistemleri uzerine Turkce literaturde ilk inceleme calismasini olusturmaktadir