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Oh, Ju-Won,Alkhalifah, Tariq SEG SOCIETY OF EXPLORATION GEOPHYSICISTS 2018 Geophysics Vol.83 No.4
<P>The orthorhombic (ORT) anisotropic description of earth layers can allow the capture of much of the earth's anisotropic complexity. The inversion for high-resolution azimuthal variation of anisotropy is important for reservoir characterization, among other applications. A high-resolution description of the azimuth of fractures can help us to predict flow preferences. To verify the feasibility of multiparameter full-waveform inversion (FWI) for marine data assuming azimuthally rotated elastic ORT media, we have analyzed the radiation patterns and gradient directions of ORT parameters to the reflection data. First, we express the gradient direction of the ORT parameters considering the azimuthal rotation of the symmetric planes. Then, to support our observations in the gradient direction, the radiation patterns of the partial derivative wavefields from each parameter perturbation are also derived under the rotated elastic ORT assumption. To find an optimal parameterization, we compare three different parameterizations: monoclinic, velocity-based, and hierarchical parameterizations. Then, we suggest an optimal multistage update strategy by analyzing the behavior of the rotation angle as a FWI target. To analyze the trade-off among parameters in different parameterizations, we calculate the gradient direction from a hockey-puck model, in which each parameter is perturbed at the different location on a horizontal layer. The trade-off analysis supports that the hierarchical parameterization provides us with more opportunities to build up subsurface models with less trade-off between parameters and less influence of the azimuthal rotation of ORT anisotropy. The feasibility of the proposed FWI strategy is examined using synthetic marine streamer data from a simple 3D reservoir model with a fractured layer.</P>
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CEO Characteristics and Firm Performance: A Study of Saudi Arabia Listed Firms
Wafa GHARDALLOU,Hela BORGI,Hibah ALKHALIFAH 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11
This paper aims to investigate the impact of chief executive officer’s (CEO) attributes on firms’ performance. Specifically, it examines the influence of CEOs’ education, professional experience, and tenure on Saudi firms’ performance. We look at a sample of 120 listed firms on Tadawul stock exchange from 2014 to 2017. Data on financial and accounting variables are obtained from the annual reports of the selected companies. We follow the existing empirical literature and use a panel model and formulate three different equations using the GMM estimator. Findings prove that CEO educational background does matter. In particular, companies employing CEOs with business administration, economics, finance, or accounting degree will perform outstandingly better. Similarly, stock performance gets improved when the CEO has a postgraduate qualification, i.e., when the CEO holds an MBA, a master, or a PhD degree. Besides, results reveal that executives who have an experience in a related field will positively affect the firm’s performance. Finally, evidence shows that high CEOs tenure improves corporate performance. Overall, these findings demonstrate that executives’ attributes are key factors that would explain differences in Saudi firms’ performance. These results would help shareholders to make the right decision in selecting CEOs to manage the company.
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An Application of Binary Soft Mappings to the Problem in Medical Expert Systems
Sabir Hussain,Mashael M.A. Alkhalifah 한국전산응용수학회 2020 Journal of applied mathematics & informatics Vol.38 No.5
We initiate and introduce the notion of binary soft mapping, which is defined on collection of binary soft sets named as binary soft class over two initial universes U_{1} and U_{2} with fixed set of parameters. We also define and study the properties of binary soft images and binary soft inverse images of binary soft sets. Examples and counter examples are also given in support of presented properties. Moreover, these concepts are applied to the problem of medical diagnosis in medical expert systems.
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