Body size varies considerably among species and among populations within species, exhibiting many repeatable patterns. However, which sources of selection generate geographic patterns, and which components of fitness mediate evolution of body size, are not well understood. For many animals, resource quality and intraspecific competition may mediate selection on body size producing large-scale g...

A low voltage drive linear ultrasonic motor with a semi-oval shaped stator is proposed in this paper. In the stator, two multilayer piezoelectric actuators are clamped in the holder of the stator by pre-stressing to excite a semi-oval ring. The semi-oval shaped stator is designed to have normal vibration and tangential vibration modes, thus these two orthogonal mechanical vibration modes of the...

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNOLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Andrej Burakov Name of the dissertation Modelling the unbalanced magnetic pull in eccentric-rotor electrical machines with parallel windings Manuscript submitted 08.06.2007 Manuscript revised 07.10.2007 Date of the defence 25.10.2007 Monograph Article dissertation (summary + original ...

The bacterial flagellar motor is driven by the electrochemical potential of specific ions, H(+) or Na(+). The motor consists of a rotor and stator, and their interaction generates rotation. The stator, which is composed of PomA and PomB in the Na(+) motor of Vibrio alginolyticus, is thought to be a torque generator converting the energy of ion flux into mechanical power. We found that specific ...

This paper deals with the design and performance analysis of double stator axial flux permanent magnet generators for rim-driven marine current turbines (MCT). Indeed for submarine applications, drive train reliability is a key feature to reduce maintenance requirements. Rim-driven direct-drive multi-stator generators can therefore be a very interesting solution to improve this reliability. In ...

PomA and PomB are transmembrane proteins that form the stator complex in the sodium-driven flagellar motor of Vibrio alginolyticus and are believed to surround the rotor part of the flagellar motor. We constructed and observed green fluorescent protein (GFP) fusions of the stator proteins PomA and PomB in living cells to clarify how stator proteins are assembled and installed into the flagellar...

air spindles are one of the main elements of precise machine tools. vibration of these spindles is one of the vital issues necessary for investigation. among parameters which influence air spindle vibrations are rotational speed, compression air method, input nozzle diameter, air gap pressure. in this study using ansys, the effects of air gap thickness on air spindle vibrations have been invest...

The first objective of this research is to present an improved Direct Torque Control based on the Space Vector Modulation (DTC-SVM) and a Sliding Mode Observer (SMO). The disadvantages of the conventional Direct Torque Control (DTC) are the high ripples for the electromagnetic torque and the stator flux, as well as the distortions of the stator current. To solve these problems, we have used the...

A dual stator winding squirrel-cage induction motor (DSWIM) is a brushless single-frame induction motor that contains a stator with two isolated three-phase windings wound with dissimilar numbers of poles. Each stator winding is fed by an independent three-phase inverter. The appropriate efficiency of this motor is obtained when the ratio of two frequencies feeding the machine is equal to the r...

The numerous qualities of squirrel cage induction machines enhance their use in industry. However, various faults can occur, such as stator short-circuits and rotor failures. In this paper, we use a technique based on the spectral analysis of stator current in order to detect the fault in the machine: broken rotor bars. Thus, the number effect of the breaks has been highlighted. The effect is h...