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F. Bayat

Bio: F. Bayat is an academic researcher from Lehigh University. The author has contributed to research in topics: Pressure drop & Duct (flow). The author has an hindex of 1, co-authored 1 publications receiving 18 citations.

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TL;DR: In this article , the authors compared the portfolio return, risk and covariances of 10 stocks traded in BIST100 between 1.1.2011-31.4.2021 according to Modern Portfolio theory and Downside risk criteria.
Abstract: The concept of risk entered the portfolio world with the work of Harry Markowitz. By considering risk and return together, Markowitz accepts the return distribution symmetrically to create optimal portfolios so that investors can obtain the least risk (variance) and the highest return. When the return distribution is symmetrical, variance can give accurate results as an indicator of risk. But what if the returns show an asymmetrical distribution, can this be the case? Based on this question, the purpose of our research is to compare the portfolio return, risk and covariances of 10 different stocks traded in BIST100 between 1.1.2011-31.4.2021 according to Modern Portfolio theory and Downside risk criteria. In our study, it has been found that Modern Portfolio does not diversify sufficiently, creates portfolios from stocks with high return-risk features, and when the returns do not show a symmetrical distribution, it is insufficient. On the contrary, it has been understood that portfolios created against downside risk measures contain less risk and that more accurate results can be achieved with downside risk measures in asymmetric return distribution.

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TL;DR: In this paper, the effects of Coriolis force, centrifugal force, and thermal buoyancy force on an air-filled, differentially heated enclosure of square cross section, with the enclosure rotated about its horizontal axis, are classified numerically.
Abstract: The effects of Coriolis force, centrifugal force, and thermal buoyancy force are segregated numerically on an air-filled, differentially heated enclosure of square cross section, with the enclosure rotated about its horizontal axis. The physically realizable periodic oscillation solutions are identified with reported experimental results of six temperature fields. The evolution of the flow pattern in the natural-convection flow fields are studied from stationary to increasing rotation of the enclosure. The effects of Coriolis force and centrifugal force on the natural convection are small and are differentiated from those of other forces.

27 citations

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TL;DR: In this paper, the development of three-dimensional heat transfer and fluid flow in a square channel rotating in a parallel mode has been investigated numerically, and the generalized model is used to mathematically simulate the momentum equations employing the Boussinesq approximation for the density variation.

24 citations

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TL;DR: In this article, the combined heat transfer of convection and radiation in rectangular ducts rotating in a parallel mode was investigated numerically in detail, and the coupled momentum and energy equations were solved by the DuFort-Frankel numerical scheme to examine the interactions of the convection with radiation.

23 citations

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TL;DR: In this paper, the rotation-induced thermal buoyancy effects stemming from the coexistence of rotational body forces and the nonuniformity of the fluid temperature field are considered.
Abstract: The present paper is concerned with the non-isothermal flow mechanisms in rotating systems with emphasis on the rotation-induced thermal buoyancy effects stemming from the coexistence of rotational body forces and the nonuniformity of the fluid temperature field. Non-isothermal flow in rotating ducts of radial and parallel modes and rotating cylindrical configurations, including rotating cylinders and disk systems, are considered. Previous investigations closely related to the rotational buoyancy are surveyed. The mechanisms of the rotation-induced buoyancy are manifested by the author's recent theoretical results and scaling analyses pertaining to the rotation-induced buoyancy in rotating ducts and two-disk systems. Finally, the open issues for future researches in this area are proposed.

21 citations