نتایج جستجو برای: magnet
تعداد نتایج: 18990 فیلتر نتایج به سال:
The MAX IV 3 GeV storage ring, currently under construction, pursues the goal of low electron beam emittance by using a multi-bend achromat magnet lattice, which is realised by having several consecutive magnet elements precision-machined out of a common solid iron block, 2.3-3.4 m long. With this magnet design solution, instead of having 1320 individual magnets, the MAX IV 3 GeV storage ring i...
Studies of the two-dimensional motion of a magnet sphere in the presence of a second, fixed sphere provide a convenient venue for exploring magnet–magnet interactions, inertia, friction, and rich nonlinear dynamical behavior. These studies exploit the equivalence of these magnetic interactions to the interactions between two equivalent point dipoles. We show that magnet–magnet friction plays a ...
This paper describes the NMR/MRI magnets that are currently being developed at the MIT Francis Bitter Magnet Laboratory: 1) a 1.3 GHz NMR magnet; 2) a compact NMR magnet assembled from YBCO annuli; and 3) a persistent-mode, fully-protected 0.5-T/800-mm whole-body MRI magnet.
To control and drive a robotic capsule accurately from outside a patient's body, we present a schema in which the capsule enclosing the imaging device, circuits, batteries, etc is looped by a permanent magnet ring that acts as an actuator. A cuboidal permanent magnet situated outside the patient's body attracts or pushes the magnet ring from different directions to make the capsule move or rota...
BACKGROUND Although there is evidence that hospitals recognized for nursing excellence--Magnet hospitals--are successful in attracting and retaining nurses, it is uncertain whether Magnet recognition is associated with better patient outcomes than non-Magnets, and if so why. OBJECTIVES To determine whether Magnet hospitals have lower risk-adjusted mortality and failure-to-rescue compared with...
Despite being a core networking primitive, collection protocols today often suffer from poor reliability (e.g., 70%) in practice, and heavily used protocols have never been evaluated in terms of communication efficiency. Using detailed experimental studies, we describe three challenges that cause existing collection protocols to have poor reliability and waste energy: inaccuracies in link estim...
Background: Magnet therapy has been used increasingly as a new method to alleviate pain. Magnetic products are marketed with claims of effectiveness for reducing pain of various origins. However, there are inconsistent results from a limited number of randomized controlled trials (RCTs) testing the analgesic efficacy of magnet therapy. This study aimed to evaluate the safety and effectiveness o...
The cylindrical permanent magnet is the core part of the permanent-magnet seed-metering device, it can absorb single magnetic powder coated seed. The first, the magnetic induction intensity model of any point in the cylindrical permanent magnet external was established based on the equivalent current model of permanent magnet. The second, the mathematical formula was derived using the Biot-Sava...
In this paper an approach of ferromagnetic shimming for permanent MRI magnet is presented. It is designed to reduce unhomogeneity of magnetostatic field of permanent magnet to meet the stringent requirement for MRI applications. An optimal configuration of ferromagnetic pieces is generated through calculation according to the initial field map and the demanded final homogeneity specifications. ...
We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was abou...
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