INTRODUCTION Khat is known in Somalia as "qaad" or "jaad". It is a plant whose leaves and stem tips are used as stimulant or medicine in certain areas of East Africa, Madagascar and Arabia. The consumers get a feeling of well-being and mental alertness with loquacity, excitement and sometimes anxiety (Halbach 1972). To achieve the climax of such feeling, they continue chewing for four to six ho...

A resonance detection scheme and some useful ideas for cavity-based searches of light cold dark matter particles (such as axions) are presented, as an effort to aid in the on-going endeavors in this direction as well as for future experiments, especially in possibly developing a table-top experiment. The scheme is based on our idea of a resonant detector, incorporating an integrated Tunnel Diod...

A light weight, simple design NMR apparatus consists of 24 identical magnets arranged inHalbach array was designed and built. The homogeneity of the magnetic field B0 can be improved bydividing a long magnets into several rings. The size of the useful volume depends on both the gapbetween each ring and some others shim magnets. Our aim is to enhance the sensitive volume and toma...

High performance force sensors often encounter the problem of vibrations during the process of calibration and measurement. To address this problem, this paper presents a novel passive eddy current damper (ECD) for vibration suppression. The conceived ECD utilizes eight tubular permanent magnets, arranged in Halbach array, and a conductive copper rod to generate damping. The ECD does not requir...

Abstract: In order to realize the high speed and high-precision control of a maglev planar motor, a high-precision electromagnetic model is needed in the first place, which can also contribute to meeting the real-time running requirements. Traditionally, the electromagnetic model is based on analytical calculations. However, this neglects the model simplification and the manufacturing errors, w...

The traditional model of the electromagnetic force and torque does not take the coil corners into account, which is the major cause for the motor fluctuation. To reduce the fluctuation, a more accurate real-time computation model, which considers the influence of the coil corners, is proposed in this paper. Three coordinate systems respectively for the stator, the mover, and the corner are esta...