Activity Theory Based Ontology Model for Efficient Knowledge Sharing in eHealth

Knowledge sharing has become an important issue that challenges the efficient healthcare delivery in eHealth system. It also rises as one of the most demanding applications with reference to dynamic interactivities among various healthcare actors (e.g. doctors, nurses, patients, relatives of patients). In this paper, we suggest an activity theory based ontology model to represent various healthcare actors. The goal of the suggested model is to enhance interactivities among these healthcare actors for conducting more efficient knowledge sharing, which helps to design eHealth system. To validate the feasibility of suggested ontology model, three typical use cases are further studied. A questionnaire based survey is carried out and the corresponding survey results are reported, together with the detailed discussions.

High-frequency MnZn soft magnetic ferrite by engineering grain boundaries with multiple-ion doping

MnZn soft magnetic ferrites have been widely utilized in power electronics,owing to the combined merits of high permeability and low energy loss.However,their deployment would result in a drastic increase in power dissipation at>3 MHz,thus limiting the scope extent of miniaturization,together with their efficiency.Here,we report a high-performance MnZn ferrite by doping multiple ions(La,Ti,Si,Ca)at grain boundaries,achieving the most optimized power loss of 267 kW/m^(3) at 5 MHz(10 m T,100℃)and initial permeability of 644,which is much better than the previously reported results and commercial products.Such an improvement is attributed to weakened magnetic exchange coupling at grain-boundary regions,associated with a significant transition from the multi-to mono-domain structures,originating physically from large crystallographic mis-orientations(>25°).The present study bears important significance in understanding the intrinsic correlation between the crystallographic mis-orientation and magnetic domain structure,and provides an alternative way for optimizing high-frequency soft magnetic ferrites.

Synergistic effect of V_(2)O_(5)and Bi_(2)O_(3) on the grain boundary structure of high-frequency NiCuZn ferrite ceramics

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss(Pcv)at megahertz frequencies.Here,we prepared NiCuZn ferrite with superior high-frequency properties by V_(2)O_(5)and Bi_(2)O_(3)synergistic doping,which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies.The sample doped with 800 ppm V_(2)O_(5)and 800 ppm Bi_(2)O_(3)yielded the most optimized magnetic properties with a Pcv of 113 kW/m^(3)(10 MHz,5 mT,25℃),an initial permeability(μi)of 89,and a saturation induction(Bs)of 340 mT,which is at the forefront of the reported results.These outstanding properties are closely related to the notable grain boundary structure,which features a new type of nano-Bi_(2)Fe_(4)O_(9)phase around ferrite grains and a Ca/Si/V/O amorphous layer.Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.