Lead-free Nb-based dielectric film capacitors for energy storage applications

Dielectric capacitors are the ideal energy storage devices because they have excellent power density,high working voltages,and a long lifespan.With its lower size and better energy storage density,film capacitors make them simpler to incorporate into circuits than traditional dielectric capacitor devices.Lead-free Nb-based perovskite ferroelectric/antiferroelectric films have strong orbital hybridization with O 2p orbitals due to unfilled d orbitals of Nb elements,forming a series of energy storage film materials with potential application value.Here,we provide an overview of the state-of-the-art lead-free Nb-based films for energy storage applications,which include K_(0.5)Na_(0.5)NbO_(3)-based,K_(0.5)Na_(0.5)Bi_(4)NbTi_(3)O_(15)-based,AgNbO_(3)-based and NaNbO_(3)-based films.An overview of the benefits and drawbacks of each kind of Nb-based perovskite ferroelectric/antiferroelectric films is provided,along with a description of the design tactics used to achieve high energy storage performances.

Vascular segmentation of neuroimages based on a prior shape and local statistics

Fast and accurate extraction of vascular structures from medical images is fundamental for many clinical procedures.However,most of the vessel segmentation techniques ignore the existence of the isolated and redundant points in the segmentation results.In this study,we propose a vascular segmentation method based on a prior shape and local statistics.It could efficiently eliminate outliers and accurately segment thick and thin vessels.First,an improved vesselness filter is defined.This quantifies the likelihood of each voxel belonging to a bright tubular-shaped structure.A matching and connection process is then performed to obtain a blood-vessel mask.Finally,the region-growing method based on local statistics is implemented on the vessel mask to obtain the whole vascular tree without outliers.Experiments and comparisons with Frangi’s and Yang’s models on real magneticresonance-angiography images demonstrate that the proposed method can remove outliers while preserving the connectivity of vessel branches.