SEARCH RESULT

Among the electrical machines the shaded pole motors are the most difficult ones in terms of modeling and analysis. This difficulty is arising from the non-uniform airgap and unbalanced windings on its stator. Because ofthese the airgap flux contains rich space harmonics, and this complicates the mathematical modeling and simulation of these machines. On the other hand, small size of these machines results in strong end effects. Hence the 3-D modeling of magnetic field analysis poses an important advantage. Therefore, in this presentation a 15 W, 4 pole shaded pole motor has been modelled in 3-D using Finite Elements (FE) method to determine some important performance parameters such as the airgap flux distribution and the saturation effects in the motor laminations. In this process magnetic field distribution have been obtained for three different case which are: a) Main winding is excited but shading rings and rotor cage are not excited b) Shading rings are excited, but stator winding and rotor cage are not excited c) Both the stator winding and shading rings are excited, but rotor cage is not excited Finally, advantages accrued from such an analysis is discussedin detail.

International Conference on Advanced Technologies, Computer Engineering and Science
ICATCES

Adem Dalcalı Mehmet Akbaba

Researchers have been studying to understand and classify biological signals for better diagnose diseases and developing assistive technologies. These technologies are sometimes making it possible to communicate in ALS (Amyotrophic lateral sclerosis) patients, sometimes possible to use our computer, faster and more efficient without using our muscular systems. The steady state visual evoked potential (SSVEP) approach currently provides the high performance and reliable communication for the implementation of these technologies. Performance is usually measured by Information Transfer Rate (ITR) and the most important factor affecting ITR is signal window length. In the presented paper a SSVEP based BCI (Brain Computer Interface) speller application is introduced and system performance is analyzed for different signal window lengths in experiments. The BCI speller has six box which has six letters in each box on the screen. The six letters in the selected box are distributed as one letter each box after the first selection by application. With the second selection, the letter which desired is displayed on the screen. The application contains Latin letters as well as Turkish letters. Experiments are performed on 3 healthy subjects. Subjects try to choose letter by focusing boxes which has flickering different frequencies. The minimum energy combination (MEC) method is applied to EEG segments that are different length in order to detect SSVEPs. The highest ITR value of 77.55 bit/min is obtained for subject 1 with 2 s signal window length. High accuracy and more useful a BCI system observed when system signal window length set 3 s.

International Conference on Advanced Technologies, Computer Engineering and Science
ICATCES

E. ERKAN Mehmet Akbaba

Recently, through development of several 3d vision systems, widely used in various applications, medical and biometric fields. Microsoft kinect sensor have been most of used camera among 3d vision systems. Microsoft kinect sensor can obtain depth images of a scene and 3d coordinates of human joints. Thus, anthropometric features can extractable easily. Anthropometric feature and 3d joint coordinate raw datas which captured from kinect sensor is unstable. The strongest reason for this, datas vary by distance between joints of individual and location of kinect sensor. Consequently, usage of this datas without kinect calibration and data optimization does not result in sufficient and healthy. In this study, proposed a novel method to calibrating kinect sensor and optimizing skeleton features. Results indicate that the proposed method is quite effective and worthy of further study in more general scenarios.

International Conference on Advanced Technologies, Computer Engineering and Science
ICATCES

Mahmut Selman Gökmen Mehmet Akbaba Oğuz Findik

A system is a set of interacting components are connectedin such a way that the vibration or response in the state of one component affects the state of others. A dynamic system is described by time differential equations; therefore, the future response of the system is determined by the present state of the system (the initial conditions) and the present input. Modeling and simulation are the prerequisite to the design of a dynamic system, as the designing and manufacturing a system and then testing it for expected performance would be unavoidably expensive. Wide spread availability of high speed and high storage capacity computers makes the simulation process even more attractive before the manufacturing stage for observing the expected performance of complex dynamic systems. However, before simulation phase of a system the mathematical model of the system must be prepared. For complex mechanical systems it is not always easy to establish the mathematical model. On the other hand, it is much easier to establish the mathematical model of an electrical system. Furthermore, simulation software is richer for electrical systems. For these reasons in this manuscript modeling of a complex mechanical systems will be realized using electrical circuit analog and then will be simulated as an electrical circuit. Advantages of this approach will be explored.

International Conference on Advanced Technologies, Computer Engineering and Science
ICATCES

Mehmet Akbaba Adem Dalcalı M. GÖKDAĞ

In iron and steel industry electric motor systems consume around 7% of total energy use. This rate is even more in some special applications. Motor systems include motor driven units such as rolling mills, pumps, conveyors, fans and material handling equipment. In many cases motors used in this industry are aged motors of standard efficiency class that are consuming much more energy than the new generation energy efficient motors. Solution to this problem is to retrofit the existing even healthy standard efficiency motors by the new generation energy efficient motors. In some countries governmental regulations makes it mandatory to retrofit the standard efficiency motors with the new generation energy efficient class motors, where in most countries around the globe this matter remains as recommendation. Depending on the energy cost in each country the pay-back periods varies between 2 years to 6 years. For the countries such as Turkey where the energy prices are very high the pay-back periods for electric motor retrofits will be about 2 to 3 years or less than that. This means that a motor retrofit will cover the installation and new motor cost mostly within approximately 2 to 3 years or less and then energy and cost saving will start for free thereafter. Retrofit means replacing and old but operating healthy motor of standard efficiency with a new higher efficiency motor.In this investigation several scenarios will be presented on the energy and cost saving by motor retrofit and pay-back periods will be determined in details. Importance of the dependency on the energy prices, benefits of motor retrofit to the iron and steel industry and environmental pollution will be explored with several examples when using different sizes of electric motors. It will be shown that the size of the motor plays an important role on the pay-back period and that the energy and cost saving is more significant for retrofitting small and medium size motors up to100 kW, which are more commonly used motor sizes in the iron and steel industry.

International Iron & Steel Symposium
UDCS

Mehmet Akbaba