Determination of Critical Volumes in Recording Media

1998 ◽  
Vol 517 ◽  
Author(s):  
K. O'Grady ◽  
P. Dova ◽  
H. Laidler
Keyword(s):  
Waiting Time ◽  
Thermal Activation ◽  
Activation Volume ◽  
Recording Media ◽  
Thermal Loss ◽  
Ultrahigh Density

AbstractIn this overview paper the concept of thermal activation of magnetisation reversal is reviewed in terms of the Wohlfarth-Gaunt formalism. This formalism gave rise to the concept of an activation volume of reversal. Other techniques have been developed for the determination of activation or critical volumes of reversal and these are reviewed. It is found that these methods give the same approximate value for the activation volume but the only method based on micromagnetism is the waiting time experiment which is consistent with Gaunt. Factors which affect the activation volume such as incoherent reversal and intergranular coupling are discussed together with measures that may be required in order to generate ultrahigh density recording media that are relatively free from thermal loss of signal.

scholarly journals Fast and Slow Magnetization Processes in Magnetic Recording Media

2005 ◽  
Vol 887 ◽  
Author(s):  
J. Zhou ◽  
R. Skomski ◽  
S. Michalski ◽  
R. D. Kirby ◽  
D. J. Sellmyer
Keyword(s):  
Magnetic Recording ◽  
Remanent Magnetization ◽  
Thermal Activation ◽  
Information Loss ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Local Anisotropy ◽  
Thermally Activated ◽  
Ultrahigh Density ◽  
Magnetization Processes

ABSTRACTInformation loss due to thermal activation is a major concern in ultrahigh-density magnetic recording media. The usually considered mechanism is thermally activated magnetization reversal over micromagnetic energy barriers. However, micromagnetic approaches ignore local anisotropy fluctuations, which translate into a time-dependent reduction of the remanent magnetization. The effect is negligibly small in macroscopic magnets but becomes important on a scale of a few nanometers.

Determination of anisotropy fields in recording media

2000 ◽  
Vol 87 (9) ◽  
pp. 5711-5713 ◽  
Author(s):  
G. R. Jones ◽  
L. S. Prichard ◽  
J. A. Hutchings ◽  
H. Laidler ◽  
K. O'Grady
Keyword(s):  
Recording Media

Activation Volume Measurements

1971 ◽  
Vol 26 (2) ◽  
pp. 291-299 ◽  
Author(s):  
Michele Beyeler ◽  
David Lazarus
Keyword(s):  
Sodium Chloride ◽  
Hydrostatic Pressure ◽  
Ionic Conductivity ◽  
Activation Volume ◽  
Tracer Diffusion ◽  
Accurate Temperature ◽  
Volume Measurements ◽  
Accurate Temperature Control ◽  
Effect Of Hydrostatic Pressure

Abstract The determination of the activation volume of diffusion is one of the best methods for the in­vestigation of the relaxation of atoms or ions around defects. This paper discusses two experimental techniques for the determination of the activation volume for diffusion, by studying the effect of hydrostatic pressure on tracer diffusion and on ionic conductivity. Such experiments require a very clean hydrostatic pressure environment, accurate temperature control and measurement, and well defined specimen geometry. The difficulties encountered during such experiments are discussed. Results are given for the activation volumes of diffusion in beryllium and in sodium chloride.

scholarly journals Determination of Necessary Subsidiary Track According to Train Operation Frequency in a Heterogeneous Train Pattern

2020 ◽  
Vol 10 (12) ◽  
pp. 4164
Author(s):  
Hyoung June Kim
Keyword(s):  
Genetic Algorithm ◽  
Waiting Time ◽  
High Speed ◽  
The Third ◽  
Railway Construction ◽  
Different Types ◽  
High Speed Trains ◽  
Train Operation ◽  
Operation Frequency

In this study, a genetic algorithm was used to calculate the scheduled waiting time according to the train operation frequency of heterogeneous trains operating on one track. The acquired data were then used to determine the appropriate subsidiary track at which high-speed trains can load or release cargo away from low-speed trains. A metaheuristic genetic algorithm was applied and implemented using Javascript/jQuery. Six cases were investigated, which provided values of subsidiary track that vary according to the operation frequencies of different types of trains, and solutions were derived through 100 simulations using a stochastic method. The analysis results showed that the train overtaking frequency was the highest at the third intermediate station within the simulation, suggesting that this particular station requires a subsidiary track, even if the operating frequency of each train differs across the entire track considered in this study. The results of this study are expected to facilitate objective and practical planning during railway construction.

Sign in / Sign up

Export Citation Format

Share Document