A Hybrid Stabilized Finite Element/Finite Difference Method for Unsteady Viscoelastic Flows
Ahmed Elhanafy,
Amr Guaily,
Ahmed Elsaid
Issue:
Volume 1, Issue 2, December 2016
Pages:
26-35
Received:
10 September 2016
Accepted:
14 October 2016
Published:
21 October 2016
DOI:
10.11648/j.mma.20160102.11
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Abstract: The Oldroyd-B constitutive equation is used for the numerical simulation of unsteady incompressible viscoelastic flows. A novelty treatment is presented for the incompressibility constraint of the incompressible viscoelastic flow by using the modified continuity equation which allows using equal-order interpolation polynomials for all variables. The proposed technique circumvents the so-called LBB compatibility condition without pressure checkerboard and the solution instabilities with less computational costs compared with the traditional techniques. The discrete elastic-viscous stress-splitting method (DEVSS) is used to treat the instabilities resulting from the numerical simulation of viscoelastic flows. Two benchmark problems are simulated, namely, the flow through a channel with a bump and the flow inside a square cavity. Solutions are obtained for different Weissenberg number values and the results are compared with the published works.
Abstract: The Oldroyd-B constitutive equation is used for the numerical simulation of unsteady incompressible viscoelastic flows. A novelty treatment is presented for the incompressibility constraint of the incompressible viscoelastic flow by using the modified continuity equation which allows using equal-order interpolation polynomials for all variables. Th...
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Utility of Correlation Measures for Weighted Hesitant Fuzzy Sets in Medical Diagnosis Problems
Issue:
Volume 1, Issue 2, December 2016
Pages:
36-45
Received:
22 December 2015
Accepted:
15 February 2016
Published:
28 October 2016
DOI:
10.11648/j.mma.20160102.12
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Abstract: Due to importance of correlation measure in data analysis, some researchers have shown great interest in the concept of correlation measure for extensions of fuzzy sets, in particular, for a new extension known as hesitant fuzzy set (HFS). Recently, an extension of HFS called the weighted hesitant fuzzy set (WHFS) has been developed by Zhang and Wu [1] to allow the membership of a given element is defined in terms of several possible values together with their importance weight. But, Zhang and Wu’s definition of WHFS gives rise to a number of disadvantages which violate the well-known axioms for mathematical operations. To circumvent this issue, we refine the definition of WHFS and then we put forward some correlation measures for WHFSs. Finally, we give a practical example to illustrate the application of proposed correlation measures for WHFSs in medical diagnosis.
Abstract: Due to importance of correlation measure in data analysis, some researchers have shown great interest in the concept of correlation measure for extensions of fuzzy sets, in particular, for a new extension known as hesitant fuzzy set (HFS). Recently, an extension of HFS called the weighted hesitant fuzzy set (WHFS) has been developed by Zhang and Wu...
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Effect of Liner Layer Properties on Noise Transmission Loss in Absorptive Mufflers
Mostafa Ranjbar,
Maryam Alinaghi
Issue:
Volume 1, Issue 2, December 2016
Pages:
46-54
Received:
27 August 2016
Accepted:
2 November 2016
Published:
25 November 2016
DOI:
10.11648/j.mma.20160102.13
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Abstract: The reduction of the emitted noise pollution from the exhaust system of engines is a real challenge for various industries. At this regard, mufflers have been used to reduce the transmitted noise from the engine of vehicles into the surrounding environment. Mufflers are designed to reflect the sound waves produced by the engine in such a way that they partially cancel themselves out. Noise transmission loss performance in muffler depends on its geometry. Therefore, maximization of noise transmission loss in mufflers using shape modification concept is an important research area. In this paper research, maximization of noise transmission in mufflers is studied and investigated. A model is developed to present the absorptive muffler. The muffler structure and its sound absorbing layer are modeled using shells elements. This model analyzes the muffler structure which has effects on the transmission loss (TL). The results are compared to a model without any absorbing layer. It indicates that the thickness and material type of absorbing layer have distinctive effects on the amount of noise transmission loss of muffler over a wide frequency range.
Abstract: The reduction of the emitted noise pollution from the exhaust system of engines is a real challenge for various industries. At this regard, mufflers have been used to reduce the transmitted noise from the engine of vehicles into the surrounding environment. Mufflers are designed to reflect the sound waves produced by the engine in such a way that t...
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On Existence and Uniqueness of Syphilis Model
Abdullahi A. A.,
Oyeniyi R. B.,
Akintunde M. A.
Issue:
Volume 1, Issue 2, December 2016
Pages:
55-58
Received:
8 September 2016
Accepted:
19 December 2016
Published:
12 January 2017
DOI:
10.11648/j.mma.20160102.14
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Abstract: A good understanding of the transmission dynamics of disease is necessary to proffer solution(s) to syphilis problem. The aim of this research was to use mathematical modelling to understand the intricacies and different approaches to Syphilis screening on epidemic dynamics and the health of MSM. A non-linear mathematical model for the transmission dynamics of syphilis in an heterogeneous setting with complications is developed and analysed. The existence and uniqueness of the system of equations is examined. We use the concept of Lipchitz criteria to analyse the model.
Abstract: A good understanding of the transmission dynamics of disease is necessary to proffer solution(s) to syphilis problem. The aim of this research was to use mathematical modelling to understand the intricacies and different approaches to Syphilis screening on epidemic dynamics and the health of MSM. A non-linear mathematical model for the transmission...
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