Iron Loss Reduction in an Interior PM Automotive Alternator

This paper examines the iron loss characteristics of a high-flux interior permanent-magnet machine. The machine was designed as a concept demonstrator for a 6-kW automotive alternator and has a wide field-weakening range. Initial experimental results revealed a high iron loss during field-weakening operation. Finite-element analysis was used to investigate the cause of the high iron losses and to predict their magnitude as a function of speed. The effects of changes in the machine design were examined in order to reduce iron losses and hence improve the machine performance     

Improved common weight MCDM model for technology selection

This paper presents an improvement on earlier work on a common weight multi-criteria decision-making (MCDM) approach for technology selection by (Karsak, E.E. and Ahiska, S.S., Practical common weight multi-criteria decision-making approach with an improved discriminating power for technology selection. Int. J. Prod. Res., 2005, 43, 1537–1554.) benefiting from a bisection search algorithm. The proposed algorithm enables to calculate the values of discriminating parameter, k, which appears in the introduced efficiency measure, in a systematic and robust manner rather than requiring the decision analyst to assign an arbitrary step size value. In addition, the paper presents comments on the model proposed by (Amin, G.R., Toloo, M. and Sohrabis, B., An improved MCDM DEA model for technology selection. Int. J. Prod. Res., 2006, 44, 2681–2686.) for technology selection. Finally, the robustness of the proposed decision-making framework is illustrated via several numerical examples taken from the above-mentioned papers.     

Indirect angle estimation in switched reluctance motor drive usingfuzzy logic based motor model

In this paper, a novel rotor position estimation scheme is described that was developed to overcome the drawbacks of the previous sensorless techniques, which were proposed for switched reluctance (SR) motor drives. It is based on fuzzy-logic, and does not require complex mathematical models or large look up tables. The scheme was implemented by using a digital signal processor. The real-time experimental results given in this paper show that the position estimation method proposed can provide accurate and continual position data over a wide range of speeds (zero/low/high), and can also function accurately at different operating conditions (chopping/single pulse mode and steady state/transient operation)     

Dynamic behavior of the flow field in a RIM machine mixing chamber

Dynamic behavior of the flow field in a Reaction Injection Molding, RIM, machine mixing chamber, having dimensions typically used in industrial machines, is studied from dynamic velocity data of Laser Doppler Anemometry, LDA, measurements and Computational Fluid Dynamics, CFD, simulations with a 2D model. This study is based on the spectral analysis of the dynamic flow field data. The typical frequencies, in the reactor flow field, are identified and its values are related to the identified flow structures. The differences between the typical frequencies from experiments and simulations are observed and justified on the basis of the 2D representation of a 3D cylindrical geometry. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Uncontrolled generation in interior permanent-magnet Machines

The movement toward higher power automotive electrical systems has spurred research into low-cost alternators capable of operating over a wide constant-power speed range. A promising candidate for this application is a specially designed interior permanent-magnet (IPM) machine operating in uncontrolled generation (UCG). This paper investigates the modeling and performance of IPM machines in UCG. The concept of the voltage-current locus is introduced to explain the presence of hysteresis in the machine stator current and this effect is experimentally demonstrated. The effect of nonidealities such as magnetic saturation and stator resistance are also examined, to achieve a more accurate steady-state and dynamic modeling of the machine behavior. The predictions of these models are tested against experimental results.     

Microwave coaxial slot bridge technique for the dielectric parameter control of liquids

The basic physical principles and construction of the device for investigation of dielectric parameters of liquids are considered. The key moment is in the using of the rigorous solution of initial boundary value problem for the resonant electromagnetic structure that is in the focus of the device. Thus all electromagnetic characteristics are calculated with the required accuracy and several rather special phenomena are taken into account.     

Mechanical,thermal and morphological properties of heat-treated wood-polypropylene composites and comparison of the composites with PROMETHEE method

ABSTRACT

The aim of the paper was to determine the mechanical, thermal, and morphological properties of heat-treated wood-polypropylene polymer composites (WPCs) and to select the composites having the optimum properties with the PROMETHEE method. In this study, polypropylene (PP) as a matrix, wood thermally treated at 180°C and 220°C as reinforcement filler were examined for preparing composites. The PP composites were compounded using a twin-screw extruder and test specimens were prepared by compression moulding. According to the test results, the thermal and mechanical properties of the WPCs generally increased with the addition of heat-treated wood fillers. The SEM images showed that the wood fillers dispersed better in the PP matrix as the particle size decreased from 40 mesh to 100 mesh. The WPCs having the optimum mechanical and thermal properties were determined for 40 mesh heat-treated wood at 220°C and 20?wt-% loadings with PROMETHEE method.     

Zeta potential study of natural‐ and acid‐activated sepiolites in electrolyte solutions

Detailed characterisation of natural sepiolite from the Eskisehir region of Turkey was performed using X‐ray diffraction, X‐ray fluorescence, field emission scanning electron microscopy, specific surface area (BET method), Fourier transform infrared spectra, derivative thermogravimetry (DTG) and differential thermal analysis. Electrokinetic properties of natural‐ and acid‐activated sepiolites were investigated as a function of the concentration of various electrolytes, such as NaCl, KCl, LiCl, CaCl₂, MgCl₂, NaNO₃, Na₂CO₃, FeCl₃ and Al(NO₃)₃. While mono and divalent cations and anions did not change the surface charge of natural‐ and acid‐activated sepiolite, trivalent cations changed the surface charge from negative to positive. Acid‐activated sepiolite samples shifted towards the positive region in nearly all electrolyte solutions when compared with the natural sepiolite. © 2011 Canadian Society for Chemical Engineering     

The spillover effects of public capital on the Turkish private manufacturing industries in the geographical regions

This paper investigates the spillover effects of public capital formation on the Turkish private manufacturing industry at the regional level over the period 1980–2000. The aggregate effects of public capital cannot be captured entirely from the direct effects of public capital installed in the region itself. Spillovers are also an integral part of the regional impact of public capital installed in the outside of the region. Therefore, we estimate the dynamic effects of public capital using VAR models for the seven regions of Turkey by including capital formation installed outside of the region. The results show that direct effects of public capital are positive in some regions, while indirect effects of public capital are positive in most regions. A previous version of this study was presented at the METU/ERC International Conference in Economics VII, 6–9 September 2003, Ankara, Turkey.     

Planar antenna pattern nulling using differential evolution algorithm

Differential evolution algorithm is used for the pattern synthesis of planar antenna arrays with prescribed pattern nulls by position-only and position-amplitude optimization. The position-only optimization for a planar array allows null synthesis in any prescribed direction. For planar antenna array thinning it is necessary to use position-amplitude optimization for problems involving more than two nulls.