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Raza Assaf Published

Extraordinary magnetic behaviors, resistivity properties, and lattice parameters of the main sample BaFe2As2 and BaFe2-xPtxAs2 in the variation of x from 0 to 0.4 with the step of 0.1 were investigated. The bulk materials have been prepared by the solid-state reaction method and sealed into a quartz tube. The crystal structure of all samples exhibited the ThCr2Si2-type crystal structure which is in harmony with earlier studies in the literature. The superconducting states with magnetization measurements have been detailed in the wide temperature range 5-170 K, up to a field of 20 Oe. Increasing Pt and decreasing Fe elements in the BaFe2-xPtxAs2 compound deteriorated superconductivity. Using magnetization measurement data, we present the variation of superconducting critical temperature (T-c) correlating with a Pt dopant rate from x = 0 to x = 0.4. The dopant rate of x = 0.3 exhibited the limit rate for maximum Tc; deterioration of superconductivity was revealed with a dopant rate of more than x = 0.3. This should be explained by varying Tc related to a lattice shrinking and pressure effect (geometric factor).

In this study, with 15 kW induction motor is to be designed using the same stator structure and the new synchronous reluctance motor (synrm) were compared. SynRM are known as cold rotor motors. As with copper rotor induction motor (aluminum) rotor copper losses are minimized since no rods reduced to zero and the rotor losses. In this way it is achieved improvements in motor efficiency by reducing losses. Design of the rotor geometry SynRM rotor induction motor stator were performed using the same geometry. Design performing L-d / L-q rate design is made taking into consideration current barriers. The rotor lamination sheet on the air / iron ratio of parametric analysis on the lamination steel designed to be important for motor performance has been realized. This parametric analysis of lamination steel as a result it was decided to have 4 barrier. Asynchronous motors and SynRM analysis were compared. SynRM'n efficiency value according to the received value has occurred to a rise of 3%. Thus efficiency by changing the motor rotor induction class, which was raised to the IE1 IE3 class. The torque ripple is provided an improvement of approximately 8%.

In this study, a new SRM structure with lower flux than high torque and conventional winding structure is proposed in Switched Reluctance Motors (SRM). Unlike conventional SRM motors, the winding are not directly rolled over poles in the new structure. Windings are placed to somewhere closer to rotor as three layered and isolated from one another. Rotor poles which will move on both sides of each phase winding have been created. Thus, the flux created in phase windings completes its circle from stator poles and rotor poles axially. With this feature, it is different from conventional SRMs and named as axial flux switched reluctance motor (AF-SRM). The 3D magnetic analysis and parametric analysis of the proposed motor geometry have been realized in ANSYS Maxwell program. The prototype of the proposed structure has been made and experimental results and simulation results have been compared.

The friction loss of electrical machines is an important problem as like in other rotary machines. In addition, the bearings, where the friction losses occur, also require lubrication at periodic intervals and need to be maintained. In this study, to minimize the friction loss of electrical motor, two dimentional static magnetic analysis of radial magnetic bearing systems with different structures are performed and compared with each other; also, magnetic bearing system with four-pole is realized and applied to an induction motor. In simulation, the forces applied to the rotor of induction motor from designed magnetic bearing system are calculated in a computer by using FEMM software package. In application, when comparing designed magnetic bearing system with mechanical bearings up to the revolution of 350 rpm, it was observed that the loss of no-load operating condition of induction motor is decreased about 15 % with magnetic bearing system. In addition to this, mechanical noisy of the motor is also decreased considerably., Sürtünme kayıpları, diğer dönel makinalarda olduğu gibi elektrik makinalarında da önemli bir problemdir. Ayrıca, sürtünme kayıplarının oluştuğu yataklar periyodik aralıklarla yağlanmaya ve bakıma ihtiyaç duyarlar. Bu çalışmada, elektrik motorunun sürtünme kayıplarını azaltmak için, farklı yapıya sahip radyal manyetik yatak sistemlerinin iki boyutlu statik manyetik analizi yapılmış ve birbirleri ile karşılaştırılmıştır; ayrıca, dört kutba sahip manyetik yatak sistemi gerçeklenmiş ve bir asenkron motora uygulanmıştır. Simülasyonlarda, tasarlanan manyetik yatak sistemi tarafından asenkron motorun rotoruna uygulanan kuvvetler, FEMM yazılım paketi kullanan bir bilgisayar yardımıyla hesaplanmıştır. Uygulamada, manyetik yatak sistemi ile mekanik yatak sistemi 350 d/d'lık hızlara kadar karşılaştırıldığında; manyetik yataklı sistemin, asenkron motorun yüksüz çalışma kayıplarını % 15 dolaylarında azalttığı gözlenmiştir. Buna ek olarak, motorun mekanik gürültüsü de önemli derecede azalmıştır.

A 47-year-old female with a prior history of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome was admitted with transient ischemic attacks complicated by dysarthria and right-sided hemiparesis. A blood survey indicated thrombocytosis and hyperfibrinogenemia while imaging of intracranial vasculature showed occlusion of the bilateral middle cerebral arteries. POEMS syndrome, of which arterial thromboses have been mentioned as a manifestation, is rarely accompanied by transient ischemic attacks. The pathophysiologic mechanism is yet unclear and needs further investigation.

Starting performance of synchronous generators and the time in which the machine comes into steady state are important. Hence, there is much research carried out on the starting performance of synchronous generators. The more the power of the synchronous generator is, the more important its starting performance becomes. In the present study, through Ansoft Maxwell program, the design of 2.2 MW and 6600v synchronous generators was made, and then two-dimensional static magnetic analyses and two-dimensional transient analyses were performed. In this way, we were able to investigate starting losses, period of coming to steady state, phase currents and instantaneous torque values of the synchronous generators.

Y. Oner. Thermal Analysis of the Three-Phase Induction Motor and Calculation of Its Power Loss by using Lumped-Circuit Model // Electronics and Electrical Engineering.- Kaunas: Technologija, 2010.- No. 8(104). - P. 81-84. One of the most important factors to be considered in the design of a motor is the thermal structure of the motor. That is, pre-calculation of the thermal temperatures to be experienced by the parts of the motor while working should be performed and hence, appropriate materials should be selected. There are two main approaches to these calculations. These are analytic Lumped circuit model and numerical analysis. The purpose of the present study is to draw out the Lumped circuit model of three -phase induction motor and calculation of the thermal values for its parts by employing Motor cad program package. Ill. 9, bibl. 9 (in English; abstracts in English, Russian and Lithuanian).

In this study, a PV sun tracking system with the ability to move on two axes is designed. Its performance over a fixed tilted system is evaluated for the climatic condition of Denizli, Turkey. From the obtained results, it is seen that the sun tracking system improves the energy and exergy efficiency of the PV panel.

In this study, a spherical motor, consisting of a spherical rotor and a spherical magnet-stator with a simple coil and soft iron, is mentioned and designed. 3D magnetic analyses of the designed motor are conducted, and its open loop control is done by 16F877 PIC microcontroller.

In recent years, hybrid photovoltaic-hydrogen/fuel cell energy systems have been popular as energy production systems that are clean, environmental-friendly, modular, and independent from fossil fuels. In February 2007, a clean energy research facility consisting of a 5 kWp photovoltaic system and a 2.4 kWp hydrogen-fuel cell system was built to investigate these energy production technologies at Pamukkale University in Denizli, Turkey. In this hybrid energy system, electricity is generated by photovoltaic panels. Generated electrical energy is stored chemically in batteries and metal hydride hydrogen canisters. Hydrogen electrolyzed from water is transformed to DC electrical energy by two fuel cells in the case of its necessity. DC electricity produced by photovoltaic panels and fuel cells is converted to AC by two inverters for the requirements of the building. In this study, an electrical energy analysis of the building, in terms of energy efficiency, harmonics, voltage changes, voltage and current sags, voltage and current swells, transients, power outage, frequency changes etc., is performed to evaluate the power quality of the hybrid energy system. In addition, some measurements such as insulation resistance, loop impedance, line impedance, grounding resistance, and specific resistance of the ground are measured to obtain the electrical characteristics of the system. (C) 2009 Elsevier B.V. All rights reserved.

Photovoltaic (PV) panels directly convert the solar energy to electrical energy. The amount of electrical energy converted by PV panels mainly depends on incident solar radiation. Sun tracking systems can be used to maximize energy production since they ensure keeping the photovoltaic panels perpendicular to the incoming solar radiation. Spherical motors, which have the linear and circular movement ability in three independent dimensions, can be used for precisely tracking the sun as a solution. In this study, a spherical motor controlled by a micro-controller is designed for a PV-tracking system with the ability to move on two axes. Performance of PV-tracking system over a fixed tilted one is evaluated for the climate condition of Denizli, Turkey. The designed sun tracking system is observed to be improving this performance apparently using the output voltages obtained for one day. (C) 2009 Elsevier Ltd. All rights reserved.