A Comparative Study of Ionospheric Correction on SAR Interferometry—A Case Study of L’Aquila Earthquake

Synthetic Aperture Radar Interferometry(InSAR)has shown its potential on seismic deformation monitoring since it can achieve the accuracy of centimeter level or even the millimeter level.However,the irregular varieties of ionosphere can induce the additional phase delay on SAR interferometry,restricting its further application in high-precision deformation monitoring.Although several methods have been proposed to correct the ionospheric phase delay on SAR interferometry,the performances of them haven't been evaluated and compared.In this study,three commonly used methods,including polynomial fitting,azimuth offset and split-spectrum are applied to L'Aquila Earthquake to correct the ionospheric phase delay on two Phased Array type L-band Synthetic Aperture Radar(PALSAR)onboard the Advanced Land Observing Satellite-1(ALOS-1)images.The result indicates that these three methods can effectively correct the ionospheric phase delay error for SAR interferometry,where the standard deviations of the ionosphere-corrected results have decreased by almost a factor of 1.8 times for polynomial fitting method,4.2 times for azimuth offset method and 2.5 times for split-spectrum method,compared to those of the original phase.Furthermore,the result of the sliding distribution inversion of the seismic fault shows the best performance for split-spectrum method.

Experimental research based on a C-band compact transit-time oscillator with a novel diode loading an embedded soft magnetic material and shielding structure

In order to reduce the external magnetic field and improve the conversion efficiency of high-power microwave generation devices with low external magnetic field,a novel diode with an embedded soft magnetic and shielding structure is proposed.The soft magnetic material is designed to enhance the local magnetic field in the diode region.Moreover,the diode applies a shielding structure which can reduce the radial electric field.From simulation research,it is found that the emission and transmission quality of the electron beam with low magnetic field is greatly improved when loading this diode.Through simulation research,it is verified that the diode can increase the conversion efficiency of the transit-time oscillator(TTO)from 30%to 36.7%.In our experimental study,under the conditions of a diode voltage of 540 kV and a current of 10.5 kA,the output microwave power is 1.51 GW when loading the novel diode and the microwave frequency is 4.27 GHz when an external guiding magnetic field of 0.3 T is applied.The corresponding conversion efficiency is improved from 20.0%to 26.6%,which is 6.6%higher than that of a device loaded with a conventional diode.Our experiments have verified that this novel diode can effectively improve the conversion efficiency of high-power microwave sources operating with low magnetic field,and contribute to the miniaturization and compactness of high-power microwave devices.

The model of electrified cell clusters in biological tissues basing on the resting potential difference

The resting potential is the potential difference that exists between the inner and outer sides of the cell membrane when the cell is not stimulated.The resting membrane potential is a key regulator of phenomena such as cell proliferation,morphogenesis,migration and differentiation.In this paper,we proposed a model of electrified cell clusters that considers the resting potential of cell clusters in the resting state.By measuring the potential difference between the inner and outer sides of biological tissues,it is verified that the cell cluster has a negative potential difference when taking the outer potential as the reference.In the absence of external conductors,the tissue is electrically neutral;while in the presence of external conductors,the positive net charges escape freely under repulsive forces and the biological tissues form a negative electrical equilibrium system.The model proposed in this study explored the potential situation above the cellular level in the resting state,providing a new perspective for the research on resting potential.

MultiTrans:Multi-scale feature fusion transformer with transfer learning strategy for multiple organs segmentation of head and neck CT images

Radiotherapy with precise segmentation of head and neck organs at risk(OARs)is one of the important treatment methods for head and neck cancer.In routine clinical practice,OARs are manually segmented by doctors to avoid irreversible adverse reactions caused by radiotherapy,which is time-consuming and laborious.To assist doctors in OARs segmentation,a MultiTrans framework with a multi-scale feature fusion module was proposed in this paper.In the multi-scale feature fusion module,the original image and the feature map of CNN were fused together to form a compound feature map for more complete high-resolution global information.In addition,the global information was also fully utilized in MultiTrans by using the feature map restored from the compound feature map in the skip connection.The multi-scale interactive high-resolution information can make full use of medical image information and obtain features more comprehensively,thus improve the segmentation accuracy.Experiments showed that MultiTrans had an average Dice score coefficient(DSC)of 74.01%in all organs,effectively improved segmentation accuracy.In addition,we proposed a transfer learning strategy for small organs by transferring the weight parameters of organs with a large amount of data to organs with a small amount of data to speed up the convergence of MultiTrans and reduce the demand for data volume in the MultiTrans.With this strategy,the average DSC of small organs was obviously increased,making the segmentation of small organs more accurate.The proposed framework and transfer learning strategy have the potential of assisting doctors in OARs delineation.

Regulation voltage of LiNiPO_(4) by density functional theory(DFT)calculation to move towards practical application

LiNiPO_(4)(working at~5.1 V)shows potential advantages in the competition of cathode materials for lithium-ion batteries(LIBs)because of high energy density.However,the high-voltage electrolyte developed can only remain relatively stable in the range of less than 4.8V,so the operating voltage of LiNiPO_(4)needs to be adjusted to smaller to better exploit its high-voltage advantages.To regulate the operating voltage of LiNiPO_(4)while ensuring the relative stability of its electrochemical properties,in this work,all the 3d,4d,and 5d transition metals(TMs)are,respectively,doped into the Ni site of LiNiPO_(4)to screen out the doped models with excellent electrochemical performance.In particular,the changes in lattice structure,electronic properties,formation energy,mechanical properties,anisotropy,and working voltage were used as screening criteria.By considering the above screening criteria,the Cr-and Fe-doped LiNiPO_(4)with open circuit voltage~4.7 and~4.8 V are considered to have leading performance and can be used for applicable high-voltage LIBs.The screening results of this work can provide an overall understanding of the doping of LiNiPO_(4)by TMs and have advanced a theoretical idea for the design of new high-voltage LIBs cathode materials.