DSpace at IZTECH
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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.2017-08-17T10:32:10ZRecursion formula for the Green's function of a Hamiltonian for several types of Dirac delta-function potentials in curved spaces
http://hdl.handle.net/11147/6143
Recursion formula for the Green's function of a Hamiltonian for several types of Dirac delta-function potentials in curved spaces
Erman, Fatih
In this short article, we nonperturbatively derive a recursive formula for the Green's function associated with finitely many point Dirac delta potentials in one dimension. We extend this formula to the one for the Dirac delta potentials supported by regular curves embedded in two-dimensional manifolds and for the Dirac delta potentials supported by two-dimensional compact manifolds embedded in three-dimensional manifolds. Finally, this formulation allows us to find the recursive formula of the Green's function for the point Dirac delta potentials in two- and three-dimensional Riemannian manifolds, where the renormalization of coupling constant is required.
2016-01-01T00:00:00ZTraveling wave solutions for nonlinear differential-difference equations of rational types
http://hdl.handle.net/11147/6142
Traveling wave solutions for nonlinear differential-difference equations of rational types
Aslan, İsmail
Differential-difference equations are considered to be hybrid systems because the spatial variable n is discrete while the time t is usually kept continuous. Although a considerable amount of research has been carried out in the field of nonlinear differential-difference equations, the majority of the results deal with polynomial types. Limited research has been reported regarding such equations of rational type. In this paper we present an adaptation of the (G′/G)-expansion method to solve nonlinear rational differential-difference equations. The procedure is demonstrated using two distinct equations. Our approach allows one to construct three types of exact traveling wave solutions (hyperbolic, trigonometric, and rational) by means of the simplified form of the auxiliary equation method with reduced parameters. Our analysis leads to analytic solutions in terms of topological solitons and singular periodic functions as well.
2016-01-01T00:00:00ZZinc electrode morphology evolution in high energy density nickel-zinc batteries
http://hdl.handle.net/11147/6141
Zinc electrode morphology evolution in high energy density nickel-zinc batteries
Payer, Gizem; Ebil, Özgenç
Prismatic Nickel-Zinc (NiZn) batteries with energy densities higher than 100 Wh kg-1 were prepared using Zn electrodes with different initial morphologies. The effect of initial morphology of zinc electrode on battery capacity was investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) reveal that initial morphology of zinc electrode changes drastically after a few charge/discharge cycles regardless of initial ZnO powder used. ZnO electrodes prepared using ZnO powders synthesized from ZnCl2 and Zn(NO3)2 lead to average battery energy densities ranging between 92 Wh kg-1 and 109 Wh kg-1 while using conventional ZnO powder leads to a higher energy density, 118 Wh kg-1. Average discharge capacities of zinc electrodes vary between 270 and 345 mA g-1, much lower than reported values for nano ZnO powders in literature. Higher electrode surface area or higher electrode discharge capacity does not necessarily translate to higher battery energy density.
2016-01-01T00:00:00ZA new objective function for obstacle avoidance by redundant service robot arms
http://hdl.handle.net/11147/6140
A new objective function for obstacle avoidance by redundant service robot arms
Dede, Mehmet İsmet Can; Maaroof, Omar W.; Tatlıcıoǧlu, Enver
The performance of task-space tracking control of kinematically redundant robots regulating self-motion to ensure obstacle avoidance is studied and discussed. As the subtask objective, the links of the kinematically redundant assistive robot should avoid any collisions with the patient that is being assisted. The shortcomings of the obstacle avoidance algorithms are discussed and a new obstacle avoidance algorithm is proposed. The performance of the proposed algorithm is validated with tests that were carried out using the virtual model of a seven degrees-offreedom robot arm. The test results indicate that the developed controller for the robot manipulator is successful in both accomplishing the main-task and the sub-task objectives.
2016-01-01T00:00:00Z