China
Africa
Explore chapters and articles related to this topic
Design and Construction of Magnetic Storage Devices
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Hirofumi Kondo, Hiroshi Takino, Hiroyuki Osaki, Norio Saito, Hiroshi Kano
In principle, a magnetic recording medium consists of a permanent magnet and a pattern of remanent magnetization can be formed along the length of a single track, or a number of parallel tracks on its surface. Magnetic recording is accomplished by relative motion between a magnetic medium (tape or disk) against a stationary or rotatory read/write head. The one track example is given in Figure 12.1a. The medium is in the form of a magnetic layer supported on a nonmagnetic substrate. The recording or the reproducing head is a ring-shaped electromagnet with a gap at the surface facing the medium. When the head is fed with a current representing the signal to be recorded, the fringing field from the gap magnetizes the medium as shown in Figure 12.1b. For a constant medium velocity, the spatial variations in remanent magnetization along the length of the medium reflect the temporal variations in the head current, and constitute a recording of the signal.
Field Applications
Published in Ahmad Shahid Khan, Saurabh Kumar Mukerji, Electromagnetic Fields, 2020
Ahmad Shahid Khan, Saurabh Kumar Mukerji
Magnetic storage and magnetic recording refer to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. This stored information can be accessed by using read/write head(s). Magnetic storage media, primarily hard disks are widely used to store computer data and audio and video signals. Other examples of magnetic storage media include floppy disks, magnetic recording tape, and magnetic stripes on credit cards.
Asymmetric compressive stability of rotating annular plates
Published in European Journal of Computational Mechanics, 2019
H. Bagheri, Y. Kiani, M. R. Eslami
Eid & Adams (2006) obtained the critical speeds of a moderately thick circular spinning disk by using the Mindlin plate theory, which includes shear deformation and rotational inertia. A combination of analytical and numerical methods is used to calculate the four lowest critical speeds for a centrally clamped uniform circular disk. Comparisons between the critical speeds of the shear deformable plate with those of classical plate theory, which neglects shear deformation and rotational inertia, are made. Maretic (1998) analyzed the vibration and stability of a circular plate with elastically restrained edge induced due to the rotation with constant angular velocity. Maretic, Glavardanov, & Radomirovic (2007) analyzed the vibration and stability of a circular plate induced due to the rotation with constant angular velocity and a constant external torque. The buckled states of an annular plate under the simultaneous action of an edge torque and constant angular velocity is obtained. In this analysis asymmetric formulation is presented. Stability analysis is performed using the adjacent equilibrium criterion. Annular plates with both edges clamped are considered and solution method is based on the Galerkin method. Solution method of this research, however, is restricted to thin plates. Maretic & Glavardanov (2004) discussed the linear and nonlinear stability of a solid thin rotating circular plate subjected to uniform temperature rise loading. Stress redistribution and critical states of rotating solid circular plates are analyzed by Tutunku (2000) and Tutunku & Durdu (1998). In the mentioned works, finite element formulation is applied to obtain the critical speed of the plate. As concluded in these researches, increasing the orientation up to a certain point makes the plate less stable. Adams (1987) modelled the rotation of floppy disk with a spinning annular plate and extracted the critical states of floppy disk. In this analysis, the elastic foundation model is proposed to postpone the critical state of a rotating floppy disk. As shown in this research, certain critical speeds exist at which the spinning disk is unable to support arbitrary spatially fixed transverse loads. These critical speeds are in the range of rotational speeds relevant to certain floppy disk in magnetic recording applications. The effects of various boundary conditions on the buckling velocity is discussed by Bauer & Eidel (2007). Kiani & Eslami (2014) discussed the nonlinear stability of a functionally graded material solid circular plate subjected to uniform temperature rise and constant rotational speed. This research is limited to axisymmetric deformations. Due to the stretching-bending coupling effects in functionally graded material plates, various nonlinear responses are observed among the results. Recently Bagheri, Kiani, & Eslami (2017a) analysed the effects of uniform rotation on the critical buckling temperature of the annular plates and showed that critical buckling temperature of the plate may be enhances under certain circumstances.