DSpace College:
http://hdl.handle.net/123456789/12
Thu, 21 Nov 2019 01:21:29 GMT2019-11-21T01:21:29ZA Class of Symmetric Distributions with Bell-shaped Densities on Finite Intervals
http://hdl.handle.net/123456789/988
Title: A Class of Symmetric Distributions with Bell-shaped Densities on Finite Intervals
Authors: Abrar Bader AL-Mukhaizeem
Abstract: In this thesis, we introduce and study certain symmetric classes of continuous random variables with bell shaped density functions deﬁned on ﬁnite intervals. Speciﬁcally, we study the random variables, deﬁned over the interval (0,1), that are of the form X = W +ΘV, where the random vector (W,V) follows a Dirichlet distribution of order k = 3, with parameters (α,β,α), and Θ is a continuous random variable with a symmetric distribution deﬁned over (0,1). We investigate the properties of the joint probability distribution function of X, Θ and the marginal distribution function of X. We investigate how diﬀerent probability distributions for Θ aﬀect the distribution of X. Speciﬁcally, we exam the case when Θ follows a Beta(γ,γ) distribution and the case when Θ follows a triangular distribution. For both distributions, we determine the marginal distribution of X analytically, and investigate estimation procedures for the distribution parameters using both simulated and real data.Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/123456789/9882019-01-01T00:00:00ZCadmium(II) Ion-Selective Electrodes Based on Nanocadmium Sulfide Particles Prepared from Sparingly Soluble Cadmium(II) Salts
http://hdl.handle.net/123456789/793
Title: Cadmium(II) Ion-Selective Electrodes Based on Nanocadmium Sulfide Particles Prepared from Sparingly Soluble Cadmium(II) Salts
Authors: Abdulhakeem Abdurrahmon Ajadi
Abstract: Nano CdS particles have been prepared by a novel homogeneous precipitation method. In a solution of thioacetamide, whereby S2- ions are supplied through hydrolysis, one of the sparingly soluble salts CdCO3, CdC2O4, and CdS was brought into contact with the solution to release Cd(II) ion in infinitesimal doses. The size of the formed particles has been confined by capping the nuclei with cetyltrimethylammonium bromide (CTAB). The produced particles were characterized using UV-Visible spectrophotometry, FTIR and X-ray diffraction spectroscopy, as well as transmission electron microscopy (TEM). The results showed that the particles are capped with CTAB, have face centered cubic and hexagonal structures, and characterized by energy gaps far less than that of bulk CdS. The prepared CdS nanoparticles were used as the active ingredient in a PVC polymeric Cd(II)-ion selective electrode. The investigation of the performance characteristics of the electrode showed that it has working concentration range of 1.0 x 10-6 - 1.0 x 10-2 M, a pH range of 2.2 – 5.8, a response time of about 10 s, a life-span extending to 70 days, average detection limit of 8.65 x 10-7M average calibration graph slope of 28.56mV/concentration decade, and high selectivity towards many inorganic cations.
To determine the cause of limitation regarding the life span of the electrodes, the surfaces of exhausted and fresh electrodes have been analyzed with depth profiling X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results showed that the electrode has lost its activity as a result of leaching of the active ingredients as a result of extending use over a long time.Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/123456789/7932018-01-01T00:00:00ZBoundary Stabilization of the Modified Generalized Korteweg-de Vries-Burgers Equation
http://hdl.handle.net/123456789/782
Title: Boundary Stabilization of the Modified Generalized Korteweg-de Vries-Burgers Equation
Authors: Ala' Waddah Alalabi
Abstract: In this thesis, we study the linear and the nonlinear control problem of the Modified Generalized Korteweg-de Vries-Burgers (MGKdVB) equation:
u_t+γ_1 u^α u_x-vu_xx+μu_xxx+γ_2 u_xxxx=0, x∈(0,1), and t>0,
where v,μ,γ_1 and γ_2 are positive real numbers and α is a positive integer. First, we consider the linear boundary stabilization problem of the MGKdVB equation subject to u(0,t)=0,u(1,t)=0,u_xx (0,t)=0 and u_xx (1,t)=w(t). In the last boundary condition, w(t) plays the role of the input control. In this case, the existence and uniqueness of a global solution are proved, and the exponential stability of the MGKdVB equation in the L^2-sense is established. In addition, we propose a linear adaptive boundary control law for the MGKdVB equation when both of γ_2 and μ are unknowns. Then, we study the nonlinear non-adaptive and adaptive boundary control problems of the MGKdVB equation subject to u(0,t)=0, u_xx (0,t)=0, u_x (1,t)=w_1 (t) and u_xx (1,t)=w_2 (t), where w_1 (t) and w_2 (t) present the nonlinear boundary control. We propose two nonlinear non-adaptive boundary control laws (i.e., when v,μ,γ_1,γ_2 are known) for the equation above. Furthermore, different nonlinear adaptive boundary control schemes are proposed for the MGKdVB equation when one of the parameters v or γ_1 is unknown, when both v and γ_1 are unknowns and finally when all the parameters are unknowns. Using Lyapunov theorem, we investigate the global exponential stability of the solution in L^2 (0,1) for each of the proposed controllers. Last but not least, we support our analytical work with numerical simulations that are in a good agreement with the theoretical results.Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/123456789/7822018-01-01T00:00:00ZApproximate Approaches for Solving the Vehicle Routing Problem with Multiple Time Windows
http://hdl.handle.net/123456789/764
Title: Approximate Approaches for Solving the Vehicle Routing Problem with Multiple Time Windows
Authors: Amal Mahmoud Matar
Abstract: Faced with increasing competition and wishing to remain competitive, distribution
companies are pushed to reduce their logistics’ expenses. Their obligation to protect the
environment, reduce pollution, improve drivers’ work conditions, and deal with higher
fuel prices has geared them toward improving their vehicle routing systems. In this
context, this research studies the vehicle routing problem with multiple time windows
(VRPMTW), where each client specifies more than one time-window for the actual
delivery time. It models the problem as a constraint program and compares it to a
simplified version of an existing mixed integer program. Because VRPMTW is NP-hard,
solving it via an exact method is time consuming and without any guarantee of
convergence to optimality within a realistic runtime. Hence, most proposed methods are
approximate or heuristic. Although a heuristic does not necessarily identify the optimum,
it gives good practical results. This thesis addresses VRPMTW via a particle swarm
optimization algorithm (PSO), and tests its performance on benchmark instances from the
literature. It further hybridizes PSO with a variable neighborhood search (VNS) that
enhances the quality of each particle of the swarm. Finally, it provides computational
evidence of the utility of this hybridization in enhancing the quality of the solutions, but
recommends opting for a pure VNS.Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/123456789/7642018-01-01T00:00:00Z