OBJECT We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. MATERIALS AND METHODS The finite element method (COMSOL®) was employed for the...

The purpose of the magnet is to provide a uniform magnetic field at all points in the bore of the magnet to align mobile protons within the patient. The strength of the magnetic field is measured in units of testa or gauss-1.0 T equals 10 000 G. The magnetic field produced by the magnet is typically 30 000 times stronger than the magnetic field of the earth. Because it is not possible to obtain...

This paper presents a general method for studying the mechanical properties of a ferrofluid seal by using a three-dimensional analytical approach based on the coulombian model of a magnet. The fundamental Maxwell’s equations lead us to define the concept of magnetic energy of the ferrofluid seal by using only the three-dimensional equations of the magnetic field created by ring permanent magnet...

Faults in electrical machines can vary in severity and affect different parts of the machine. This study focuses on various kinds of short-circuits on the terminal side of a generic 20 kW surface mounted permanent magnet synchronous generator and how successive faults affect the performance of the machine. The study was conducted with the commercially available finite element method software CO...

One way of controlling AC motors for variable speed applications is through the open loop scalar control, which represents the most popular control strategy of squirrel cage AC motors. Nowadays it is used in applications, where information about the angular speed need not be known. It is suitable for a wide range of drives as it ensures robustness at the cost of reduced dynamic performance. Typ...

Based on high-throughput density functional theory calculations, we performed screening for stable magnetic MAB compounds and predicted potential strong magnets permanent magnet magnetocaloric applications.

Among the different geometrical parameters to be chosen during design of axial flux permanent magnet synchronous machines, the width of the stator slot openings near the air gap is an important parameter: it has a major influence on the power loss in the stator core and in the permanent magnets on the two rotors of the studied type of axial flux machines. Moreover, the stator slot openings para...

Introduction Development of mobile NMR and MRI has been pursued since the pioneering work on well-logging, in order to reach the performance of high-resolution systems. Permanent magnets are the key to such mobile systems and the development of rare earth NdFeB and SmCo materials allows the generation of high strength magnets. However, most systems currently used are based on bar magnets or Hal...

The space around the interaction region is some of the most highly utilized due to its importance to both CESR and CLEO. It is therefore desirable to try to optimize the design of the components in that space to a greater extent than is usually done for accelerator systems. In this paper I describe an optimization of the CESR portion of interaction region I developed and used to generate the sp...