DSOGI-PLL based power control method to mitigate control errors under disturbances of grid connected hybrid renewable power systems

The control of power converter devices is one of the main research lines in interfaced renewable energy sources, such as solar cells and wind turbines. Therefore, suitable control algorithms should be designed in order to regulate power or current properly and attain a good power quality for some disturbances, such as voltage sag/swell, voltage unbalances and fluctuations, long interruptions, and harmonics. Various synchronisation techniques based control strategies are implemented for the hybrid power system applications under unbalanced conditions in literature studies. In this paper, synchronisation algorithms based Proportional-Resonant (PR) power/current controller is applied to the hybrid power system (solar cell + wind turbine + grid), and Dual Second Order Generalized Integrator-Phase Locked Loop (DSOGI-PLL) based PR controller in stationary reference frame provides a solution to overcome these problems. The influence of various cases, such as unbalance, and harmonic conditions, is examined, analysed and compared to the PR controllers based on DSOGI-PLL and SRF-PLL. The results verify the effectiveness and correctness of the proposed DSOGI-PLL based power control method

Doctor of Philosophy

dissertationIn this dissertation, I investigate the missionary activities of the American Board of Commissioners for Foreign Missions (ABCFM) in the Ottoman Empire. I am particularly interested in exploring the impact of the activities of one of the most important missionaries, Elias Riggs, on the minorities in the Ottoman Empire throughout the nineteenth century. By analyzing the significance of his missionary work and the fruits of his intellectual and linguistic ability, we can better understand the efforts of the ABCFM missionaries to seek converts to the Protestant faith in the Ottoman Empire. I focus mainly on the period that began with Riggs' sailing from Boston to Athens in 1832 as a missionary of the ABCFM until his death in Istanbul on January 17, 1901. Elias Riggs was one of the most influential missionaries in the Ottoman Empire throughout the nineteenth century, and his life was associated with a period of significant change in the Ottoman Empire and the modern history of missionaries in the Middle East. He was instrumental in the ABCFM's decision to develop a Protestant publishing enterprise for the peoples in the region. In addition to his editorship of religious periodicals, he published a variety of books for the mission. He was a member of the translation committee for the Turkish Bible and he worked several years on translating the Bible into Armenian and Bulgarian. He had an exceptionally long career and worked in many parts of the region

Magnetic Multilayer Edges in Bernal-Stacked Hexagonal Boron Nitride

Single-layer $\it{h}$-BN is known to have edges with unique magnetism, however, in the commonly fabricated multilayer $\text{AA}^{\prime}$-$\it{h}$-BN, edge relaxations occur that create interlayer bonds and eliminate the unpaired electrons at the edge. Recently, a robust method of growing the unconventional Bernal-stacked $\it{h}$-BN (AB-$\it{h}$-BN) has been reported. Here, we use theoretical approaches to investigate the nitrogen-terminated zigzag edges in AB-$\it{h}$-BN that can be formed in a controlled fashion using a high-energy electron beam. We find that these "open" edges remain intact in bilayer and multilayer AB-$\it{h}$-BN, enabling researchers potentially to investigate these edge states experimentally. We also investigate the thermodynamics of the spin configurations at the edge by constructing a lattice model that is based on parameters extracted from a set of first-principles calculations. We find that the edge spins in neighboring layers interact very weakly, resulting in a sequence of independent spin chains in multilayer samples. By solving this model using Monte Carlo simulations, we can determine nm-scale correlation lengths at liquid-N$_{2}$ temperatures and lower. At low temperatures, these edges may be utilized in magnetoresistance and spintronics applications

Political relations between Turkey and Georgia in the post-soviet era

Georgia and Turkey has become important partners in the Caucasus region after independence of Georgia in 1991. Two countries preferred to follow pro-West policies in their foreign policy against Russian factor. They have geopolitical importance and geostrategic location for Russia throughout history. This article analyzes foreign policies of Georgia and Turkey and examines Baku-Tbilisi-Ceyhan Crude Oil Pipeline as a common foreign policy between them. The paper found out that this kind of projects between Georgia and Turkey would make them important actors rising from regional level to global level in the future

Comparison of the effects of carvedilol and nebivolol on diastolic functions of the left ventricle in patients with non-ischemic heart failure

Background: We investigated whether carvediolol or nebiovolol with vasodilator properties will produce different effects on diastolic function of the left ventricle (LV) in heart failure (HF) with low ejection fraction (EF).Methods: Sixty-one non-ischemic HF patients with EF ≤ 40% randomly received carvedilol (n = 31, 16 male) or nebivolol (n = 30, 19 male). Clinical and echocardiographic evaluations were performed at baseline, 3 and 6 months after therapy. Mitral inflow velocities (E and A waves), deceleration time of E wave (DT), isovolumetric relaxation time (IVRT), mitral annular velocities (Ea and Aa waves) were evaluated. Mitral E/A and E/Ea ratios were calculated.Results: In carvediolol and nebivolol groups, mitral E/A ratio (from 1.08 ± 0.31 to 0.87 ± 0.30 vs. from 0.98 ± 0.20 to 0.80 ± 0.20, p = 0.30) and IVRT (from 108 ± 13 to 94 ± 10 ms vs. from 107 ± 22 to 92 ± 10 ms, p = 0.25) similarly decreased while DT prolonged (from 184 ± 40 to 218 ± 42 ms vs. from 193 ± 37 to 222 ± 36 ms, p = 0.71). Also, E/Earatio significantly decreased in each group (p = 0.01), but it was lower in nebivolol group than carvedilol group at 6 months (10.2 ± 2 vs. 11.8 ± 2, p = 0.01). Carvediolol and nebivolol reduced similarly N-terminal pro-B type natriuretic peptide level (from 666 to 137 vs. 661 to 123 pg/dL, p = 0.41, respectively) and improved functional capacity (p > 0.05).Conclusions: At 6 month follow-up, carvedilol and nebivolol appear to similarly improve LV diastolic functions in non-ischemic HF patients

A New Technique for Surgical Treatment of Vaginal Agenesis Using Combined Abdominal-Perineal Approach

Optimum therapeutic approach in vaginal agenesis has always been an area of extensive controversies. Although surgical management gained priority due to the evolution of techniques, there is currently no consensus in the literature regarding the best type of surgical approach. The most commonly preferred surgical procedure among gynecologists is McIndoe operation which involves the creation of a space between bladder and rectum, insertion of a mold covered with split-thickness skin graft into that neovaginal space, and use of postoperative vaginal dilation to avoid stenosis. However, many modifications have been introduced in time in an attempt to increase the success rates. In this paper, we describe two cases with vaginal agenesis with functioning uterus who were subjected to surgery by combined abdominal-perineal approach. The surgical technique also included the use of a specially designed vaginal mold made up of polymethyl methacrylate and use of Hyalobarrier gel which is an adhesion-preventing agent