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Investigation of Carotid Atherosclerosis Ultrasound Image Using Computational Hemodynamics
No full textThis thesis is submitted to the Department of Electronics and Communication Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electronics and Communication Engineering, February, 2016.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 76-83).Brain stroke is a major cause of mortality and disability in recent decades. Carotid
atherosclerosis is considered an important contributor to the growing problem of brain stroke.
Carotid atherosclerosis resulted from an accumulation of fat, cholesterol, Calcium, and other
materials in arterial walls that create complex hemodynamics. Furthermore, elevated blood
viscosity is associated with atherosclerosis and its growth. Hence, increased blood viscosity is
also an independent risk factor for atherosclerotic diseases. Though conventional ultrasound
techniques used for flow estimation due to the real time scanning capability, still there are
scopes to enhance the image quality. Moreover, atherosclerosis related viscosity changes
effects are not considered in conventional techniques. The knowledge of the carotid artery
hemodynamics resulted due to atherosclerosis with different level of blood viscosity can
provide more information on artery stenosis and symptoms, and the risk of stroke. Therefore,
improvement in flow imaging has great clinical importance to understand the origin and
evolution of disease. Investigation and detection of viscosity change and its effect might be
helpful for better diagnosis of carotid atherosclerosis, which is a major emphasis of this thesis.
In this simulation work, hemo-disturbances have been investigated in realistic normal and
atherosclerotic carotid using finite element method (FEM) based computational fluid
dynamics (CFD) under different viscosities consideration. The computed data has been used to
simulate color flow image of blood velocities using ultrasound radio frequency (RF) signals to
considering ultrasound potentiality in atherosclerosis diagnosis. The ultrasound simulated flow
characteristics have been compared with FEM computed flow behavior and found a good
agreement between them. It has been observed that the blood velocities increase noticeably in
carotid atherosclerotic growths whereas velocities are almost uniform in the normal carotid.
The severity stages of the models have been examined quantitatively. It is also found that
viscosity induced contrast is not negligible and importantly, it is detectable from multiple steps
ultrasound flow images. The findings of this study suggest that ultrasound based blood flow
image can detect the viscosity change effect related to atherosclerosis growth. So,
incorporation of the viscosity changes contrast can enhance the quality of ultrasound flow
image. It is expected that the outcomes of this thesis work might be useful to diagnosis the
present conditions and predict the future progressions of carotid atherosclerosis to minimize
the risk of stroke.Dabasish Kumar SahaMaster of Science in Electronics and Communication Engineerin
A study on Weakly Complemented Nearlattice
No full textThis thesis is submitted to the Department of Mathematics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mathematics, July 2016.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 63-65).In this thesis study of the nature of the weakly complemented nearlattice is presented. By a nearlattice S we will always mean a meet semilattice together with the property that any two elements possessing a common upper bound, have a supremum. Cornish and referred this property as the upper bound property, and a semilattice of this nature as a semilattice with the upperbound property. Cornish and Noor [8] preferred to Hickman [7] call these semilattices as nearlattices, as the behaviour of such a semilattice is close to that of a lattice than an ordinary semilattice. Of course a nearlattice with a largest element is a lattice. Since any semilattice satisfying the descending chain condition has the upper bound property, so all finite semilattices are nearlattices. In lattice theory, it is always very difficult to study the non-distributive and non-modular lattices. Gratzer [12] studied the non-distributive lattices by introducing the concept of distributive, standard and neutral elements in lattices. Cornish and Noor [8] extended those concepts for nearlattices to study non-distributive nearlattices. On the other hand, J.C Varlet [33] studied another class of non-distributive lattices with 0 by introducing the concept of 0-distributivity. In fact this concept also generalizes the idea of pseudocomplement in a general lattice. In this thesis we have extended the concept of weakly complemented nearlattice in terms of homomorphism theorem.Mahfuza RahmanMaster of Science in Mathematic