Dynamics of coupled vortices in a pair of ferromagnetic disks

We here experimentally demonstrate that coupled gyration modes can be resonantly excited primarily by the ac current in a pair of ferromagnetic disks with varied separating distance. The sole gyrotropic mode clearly splits into a higher and a lower frequency modes for different configurations of polarities via dipolar interaction. These experimental results indicate that the magnetostatically coupled pair of vortices behaves similar to a diatomic molecule with bonding and anti-bonding states. These findings lead to the possible extension of designing the magnonic band structure in a chain or an array of vortices.Comment: 4 pages, 4 figures, accepte

Comparing technical efficiency of organic and conventional coffee farms in Nepal using data envelopment analysis (DEA) approach

Data Envelopment Analysis (DEA) approach used to estimate technical efficiency and followed by regressing the technical efficiency scores to farm specific characters under tobit regression model. Primary data was collected from random samples of 240 (120 from each) coffee famers. Mean technical efficiency score was 0.89 and 0.83 in organic and conventional coffee farming respectively. Farms operating under CRS, DRS and IRS were 31.67, 3.83 and 37.5% respectively in organic coffee and 29.17, 25 and 45.83% respectively in conventional farming areas. Tobit regression showed the variation in technical efficiency was related education, farm experience and training/extension services and excess to credit.Production frontier, Resource use, Technical efficiency, Organic, Altitude, Productivity Analysis,

Simulating Adaptive Human Bipedal Locomotion Based on Phase Resetting Using Foot-Contact Information

Humans generate bipedal walking by cooperatively manipulating their complicated and redundant musculoskeletal systems to produce adaptive behaviors in diverse environments. To elucidate the mechanisms that generate adaptive human bipedal locomotion, we conduct numerical simulations based on a musculoskeletal model and a locomotor controller constructed from anatomical and physiological findings. In particular, we focus on the adaptive mechanism using phase resetting based on the foot-contact information that modulates the walking behavior. For that purpose, we first reconstruct walking behavior from the measured kinematic data. Next, we examine the roles of phase resetting on the generation of stable locomotion by disturbing the walking model. Our results indicate that phase resetting increases the robustness of the walking behavior against perturbations, suggesting that this mechanism contributes to the generation of adaptive human bipedal locomotion

Effect of Silicon Crystallite Size on Its Electrochemical Performance for Lithium-Ion Batteries

It is reported that silicon (Si) anodes with a smaller crystallite size show better electrochemical performance in lithium-ion batteries (LIBs); Si particles with different diameters are also used. However, it is yet to be clarified whether the better performance is attributed to crystallite size or particle diameter. The effect of Si crystallite size on its anode performance using Si particles having the same diameter and different crystallite sizes is investigated. Longer cycle life is obtained for smaller crystallite size, due to the small amount of the amorphous Li-rich Li—Si phase formed during charging. The phase is likely to form in a greater amount in Si particles with larger crystallite size, leading to degradation of the Si electrode at an early stage. Furthermore, Si electrodes with larger crystallite size show superior rate performance because of the high Li diffusion rate into the broader grain boundary; on the other hand, Si with smaller crystallite size should limit Li diffusion due to the narrower grain boundary. Therefore, smaller crystallite size helps improve the cycle life but deteriorates the rate performance of LIBs