Dicle University

About: Dicle University is a education organization based out in Diyarbakır, Turkey. It is known for research contribution in the topics: Population & Catalysis. The organization has 3007 authors who have published 6368 publications receiving 94797 citations. The organization is also known as: Dicle Üniversitesi & Zanîngeha Dîcleyê.

Selection of Optimum Drilling Parameters on Burr Height Using Response Surface Methodology and Genetic Algorithm in Drilling of AISI 304 Stainless Steel

Abstract: This article illustrates an application of response surface methodology (RSM) and genetic algorithm (GA) for selecting the optimum combination values of drilling parameters affecting the burr height in drilling of AISI 304 stainless steel. The purpose of this article is to investigate the influence of the cutting parameters, such as cutting speed and feed rate, and point angle on burr height produced when drilling AISI 304 stainless steel. The experiments were conducted based on the Box–Behnken design. The measured results were collected and analyzed with the aid of a commercial software package Design Expert 6 and Matlab. A mathematical prediction model was developed using RSM) for the burr height. The effects of drilling parameters on the burr height were evaluated using RSM and optimum drilling conditions for minimizing the burr height were determined using GA. The GA optimization results have revealed that the minimum burr height was obtained at lower cutting speed and feed rates while at higher point...

A new approach to bound-state quantum electrodynamics: I. Theory

Abstract: A fully covariant two-body equation is applied to the theory of hydrogen, muonium, and positronium spectra. Both particles are treated fully relativistically and complete spin algebras for both particles are taken into account. The major part of the 16 × 16 wave equation is exactly soluble including recoil of both particles to all orders. The terms of order α 5 , α 5 are treated perturbatively (although the equation is in principle numerically solvable to all orders). Self-energy (loop) effects are partly considered by an (effective) anomalous magnetic moment, but in a dynamical way using a Pauli coupling from the beginning. The theory simplifies and improves the bound-state QED problems in a number of ways.

Influence of different power outputs of erbium, chromium:yttrium–scandium–gallium–garnet laser and acid etching on shear bond strengths of a dual-cure resin cement to enamel

Abstract: The purpose of the study was to determine if the irradiation of enamel with laser of different output powers might be viable alternatives to acid etching for the bonding of resin luting agents. Seventy-seven maxillary central incisors, extracted for periodontal reasons, were used. The enamel was etched with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser operated at one of six power outputs (0.5 W, 0.75 W, 1 W, 1.5 W, 1.75 W and 2 W) or with 38% phosphoric acid. Seventy teeth were used for the bond strength experiments, and the remaining seven (one specimen for each group) were used for scanning electron microscopy (SEM) to determine the topography and morphology of the treated enamel surface. The acid-etched group yielded the highest mean of shear bond strength (13.5 ± 2.8 MPa). The means of the shear bond strength for the teeth irradiated at 0.5 W, 0.75 W, 1 W, 1.5 W , 1.75 W and 2 W laser were 3.28 ± 2.4 MPa, 5.44 ± 3.4 MPa, 8.8 ± 4.5 MPa, 10.2 ± 4.0 MPa, 11.4 ± 4.8 MPa and 11.9 ± 4.3 MPa, respectively. Laser irradiation at 1.5 W, 1.75 W and 2 W produced a type III acid-etched pattern similar to that produced by acid etching. No significant enamel surface etching was obtained by 0.5 W or 0.75 W laser irradiation. Irradiation at 0.5 W and 0.75 W produced a type V acid-etched pattern. We concluded that the mean shear bond strength and enamel surface etching obtained with Er,Cr:YSGG laser (operated at 1.5 W and 1.75 W for 15 s) is comparable to that obtained with acid etching.