Accelerations in the Local Magnetic Field on the Adriatic Tectonic Microplate

The high level of noise is a special feature of the geomagnetic field on the territory of Slovenia. The tension of the Adriatic tectonic microplate, on which Slovenia entirely lies, was recognized as one of its sources. The interior of the Earth is also the source of geomagnetic jerks. They are impulses in the secular variation calculated on the basis of monthly or annual mean values of variation of the geomagnetic field. The paper presents an analysis of accelerations in a local magnetic field calculated on the bases of daily mean values of the magnetic field measured at PIA geomagnetic Observatory (Piran, Slovenia) in 2020. These accelerations indicate geomagnetic impulses at the regional level over days or weeks. Then these results are compared with the registered seismic activity in the West Balkans.

Interaction and local magnetic moments of metal phthalocyanine and tetraphenylporphyrin molecules on noble metal surfaces

In order to understand the Kondo effect observed in molecular systems, first-principles calculations have been widely used to predict the ground state properties of molecules on metal substrates. In this work, the interaction and the local magnetic moments of magnetic molecules （3d-metal phthalocyanine and tetraphenylporphyrin molecules） on noble metal surfaces are investigated based on the density functional theory. The calculation results show that the dz2 orbital of the transition metal atom of the molecule plays a dominant role in the molecule-surface interaction and the adsorption energy exhibits a simple declining trend as the adsorption distance increases. In addition, the Au（111） surface generally has a weak interaction with the adsorbed molecule compared with the Cu（ll 1） surface and thus serves as a better candidate substrate for studying the Kondo effect. The relation between the local magnetic moment and the Coulomb interaction U is examined by carrying out the GGA＋U calculation according to Dudarev＇s scheme. We find that the Coulomb interaction is essential for estimating the local magnetic moment in molecule-surface systems, and we suggest that the reference values of parameter U are 2 eV for Fe and 2-3 eV for Co.

GA-BASED PID NEURAL NETWORK CONTROL FOR MAGNETIC BEARING SYSTEMS

In order to overcome the system non-linearity and uncertainty inherent in magnetic bearing systems, a GA（genetic algnrithm）-based PID neural network controller is designed and trained tO emulate the operation of a complete system （magnetic bearing, controller, and power amplifiers）. The feasibility of using a neural network to control nonlinear magnetic bearing systems with unknown dynamics is demonstrated. The key concept of the control scheme is to use GA to evaluate the candidate solutions （chromosomes）, increase the generalization ability of PID neural network and avoid suffering from the local minima problem in network learning due to the use of gradient descent learning method. The simulation results show that the proposed architecture provides well robust performance and better reinforcement learning capability in controlling magnetic bearing systems.

Propagation and source of Pc5 frequency range pulsation at cusp latitude

Two induction magnetometers have been installed at Chinese Zhongshan Station and Australia Davis Station, Antarctica respectively. We adopt the cross spectral analysis technique to analyze the data of the two induction magnetometers, in June, September, December 1996 and March 1997, and to investigate Pc5 frequency range pulsation (150 600 s) occurrence and propagation in cusp latitude. The results are summarized as follows: At Zhongshan Davis Station, the magnetic pulsations in Pc5 frequency band can occurs over a wide time, but more frequently at pre local magnetic noon and pre local magnetic midnight. The Pc5 pulsations have no significant seasonal variation in the amplitude, occurrence and propagation. The amplitude has a small peak at pre local magnetic noon and large value sometimes at pre local magnetic midnight. In daytime, the Pc5 pulsations propagate westward in morning and eastward in afternoon, and reversal at local magnetic noon. In nighttime, the Pc5 pulsations propagate westward before 20:00 MLT and eastward after 20:00 MLT. Near dusk time, the Pc5 pulsations propagate irregularly. These characteristics indicate that the Pc5 pulsations have different source at different local magnetic time.

Assessing Doppler velocities of Rankin Inlet F-region echoes

Doppler velocities observed by the Rankin Inlet （RKN） PolarDARN radar are assessed with a focus on data in the beams oriented roughly along the magnetic meridian. Hourly scatter plots for every month are built. They are shown to vary widely, with median values showing very clear magnetic local time variation with maximum magnitude during pre-noon and pre-midnight hours. The histograms contain a significant amount of very small velocity data that dominates at farther ranges and during the daytime. Near noon data show generally antisunward flows but at large ranges/magnetic latitudes and very close to noon, sunward flows occur for periods of positive IMF Bz. The reverse flows are stronger during spring equinox. The velocity magnitude was found to depend linearly on the IMF Be and interplanetary electric field. Velocities are often found to be smaller than those expected from the statistical convection model of Ruohoniemi and Greenwald -1996.

A Methodology for Identifying Defects in Wire Rope Based on Permanent Magnet Excitation

A wire rope defects detection method based on permanent magnet excitation is proposed.A detection system,mainly composed of permanent magnet excitation,distance detection,multi-sensor magnetic flux leakage signal acquisition and data analysis device,is set up.According to the different characteristics of the multi-sensor magnetic flux leakage signal,the localized fault(LF)and loss of metallic cross-sectional area(LMA)signal is separated,and then the two defects can be detected.The experiments show that the method can effectively detect the two defects when they appear simultaneously on the wire rope.

Local magnetic moment oscillation around an Anderson impurity on graphene

We theoretically investigate the spin resolved Friedel oscillation(FO)and quasiparticle interference(QPI)in graphene induced by an Anderson impurity.Once the impurity becomes magnetic,the resulted FO becomes spin dependent,which gives rise to a local magnetic moment oscillation with an envelop decaying as r^(-2) in real space in the doping cases.Meanwhile,at half filling,the electron density and local magnetic moment will not oscillate but decay as r^(-3).Such spin resolved FO has both sublattice and spin asymmetry.Interestingly,the local magnetic moment decay at half filling only occurs at one sublattice of graphene,which is quite like the phenomenon observed in the STM experiment(H.González-Herrero et al.,Science 352,437(2016)).We further give an analytic formula about such spin dependent FO based on the stationary phase approximation.Finally,we study the interference of quasiparticles around the magnetic impurity by calculating the spin dependent Fourier-transformed local density of states(FT-LDOS).Our work gives a comprehensive understanding about the local magnetic moment oscillation around an Anderson impurity on graphene.

A new plasmapause location model based on THEMIS observations

A new empirical model of plasmapause location as functions of magnetic local time and geomagnetic indices has been developed based on the observations from THEMIS mission. We use the two-year data of electron density inferred from spacecraft potential to identify the plasmapause crossings and create a database of plasmapause locations. The database is further used to build up an empirical model of plasmapause related to magnetic local time based on the equation from O'Brien and Moldwin(2003). The new model is compared with previous plasmapause location models. It is found that our newly developed model is the best in predicting plasmapause locations among the existing models. The models based on Kp and Dst indices are better than the model based on AE index, suggesting that the plasmapause location is controlled by large scale convection of the magnetosphere.

Positioning system design of closed-loop magnetically driven laser steering manipulator for endoscopic microsurgery

This study presents a closed-loop magnetically driven laser steering manipulator positioning system for endoscopic microsurgery.A multimagnetic field strength sensor circuit is embedded in a 16−mm diameter analog laser steering manipulator.The magnetic field distribution of a cylindrical permanent magnet in three-dimensional space is first modeled using an integral model to overcome the large error induced by the magnetic dipole model when the sensor and permanent magnet are close.The integral in the model is then decomposed using the Gauss–Legendre quadrature to improve the computational efficiency of the formulation.Moreover,five commonly used global search optimization methods are compared.Then,the algorithm with the fastest computational rate among these five algorithms,the tree-seed algorithm,is fused with the Levenberg–Marquardt algorithm,which performs well in local search,to obtain a hybrid optimization algorithm.Finally,it is demonstrated through static and dynamic experiments that the system based on the hybrid algorithm can obtain satisfactory computational errors while maintaining a high computational rate.

Application of functional MRI in epilepsy

Objective To review the recent development of functional MRI application in epilepsy. Data sources Both Chinese and English language literatures were researched using MEDLINE/ CD ROM (1996-2005) and the Chinese Biomedical Literature Disk (1996-2005). Study selection Published articles about functional MRI application and epilepsy were selected.Data extraction Data were mainly extracted from 38 articles which are listed in the reference section of this review.Results fMRI can be used to localize seizure foci through detecting these cerebral hemodynamic changes produced by epileptiform discharges. EEG-triggered fMRI, which has higher spatial and temporal resolution, helps to detect the spatiotemporal pattern of spike origin and propagation, and define localization of the epileptogenic focus. fMRI is also useful in language and memory cognitive function assessment and presurgical assessment of refractory epilepsy. Atypically distributed cognitive function areas can be detected by fMRI, because of cortical language and memory areas reorganization during long-term epileptic activity in patients with epilepsy. Conclusions fMRI technique plays a very important role in cognitive function and presurgical assessment of patients with epilepsy. It is meaningful for understanding pathogenesis of epilepsy.

Pro-osteogenesis and in vivo tracking investigation of a dental implantation system comprising novel mTi implant and HYH-Fe particles

Insufficient early osteogenesis seriously affects the later stage osteogenic quality and osseointegration of dental implants.To promote early osteogenesis,we first designed a Ti dental implant with a built-in magnet(mTi)to produce a local static magnetic field(SMF).Then,a dental implantation system comprising the mTi implant and the superparamagnetic hydroxyapatite(HA:Yb/Ho-Fe,named HYH-Fe)particles was implanted into the alveolar bone of beagles.The results showed that the mTi+HYH-Fe group displayed better early osteogenesis and later stage osseointegration than the Ti+HA and mTi+HA groups.A combination of the local SMF(mTi)and superparamagnetic HYH-Fe particles had a positive effect on the pro-osteogenesis of Ti implants.The results also indicated that week 10 could be adopted as the key time point to evaluate the early osteogenic effect of the mTi+HYH-Fe implantation system,which would be a promising prospect for promotion of osteogenesis,in vivo tracking investigation of material-bone relationships,and clinical applications.