Application of BEMD in Extraction of Magnetic Anomaly Components Associated with Sn-W Polymetallic Mineralization in SE Yunnan,SW China

The tin(Sn)-tungsten(W)polymetallic ore concentrated district in SE Yunnan is distributed at the junction region of the Yangtze Block,the Cathaysian Block and the Indosinian Block,where there are several giant deposits of tin,tungsten,copper,silver,lead,zinc and indium closely associated with a large scale Late Cretaceous magmatism.Bi-dimensional empirical mode decomposition(BEMD)is used to extract aeromagnetic anomalous components at the survey scale of 1:200000 from the original aeromagnetic data of SE Yunnan.Four intrinsic mode functions(IMFs)and a residues component are obtained,which may reflect the geological structures and geological bodies at different spatial scales from high frequency to low frequency.The results are shown as follows:(1)Two different types of Precambrian basement in the study area were recognized:one is the Yangtze Block basement characterized by a strong positive magnetic anomaly,the other is the Cathaysian Block basement with a weak negative magnetic anomaly.The former consists of high grade metamorphic rocks including metamorphosed basic igneous rocks,while the latter consists of low grade metamorphosed sedimentary rocks.(2)The aeromagnetic anomalies associated with Sn-W polymetallic mineralization and related to granites in the study area illustrate a pattern of a skarnized alteration-mineralization zone with a positive ring magnetic anomaly enclosing a granitic intrusion with negative magnetic anomaly;(3)The ring positive magnetic anomaly zones enclosing the negative magnetic anomaly are defined as the SnW polymetallic ore-searching targets in the study area.

A review of high frequency resonant DC-DC power converters:Topologies and planar magnetic technologies

With the development of high frequency resonant DC-DC power converters,the system efficiency,power density and dynamic characteristics have been significantly improved.High frequency resonant DC-DC converters have been applied in DC grid,renewable energy,transportation,aerospace,point-of-load(POL)power supply and many other fields.Under high switching frequencies,switching loss and magnetic loss are the main concerns;thus,the resonant topology and planar magnetic are two key technologies to reduce loss.This review compares different resonant topologies and analyzes the advantages and disadvantages respectively,such as LLC circuit,dual active bridge(DAB)circuit,and other high order resonant circuits.For planar magnetic components,optimal winding structures,modeling methods and integration methods are thoroughly surveyed.With corresponding topics,the opportunities and challenges in the future development are summarized,which mainly focus on the characteristics of wide bandgap devices,such as the dynamic resistance,output capacitance loss and also the integrated module.This review can be a helpful guidance when designing high frequency resonant DC-DC converters.

Ultrasensitive magnetic field sensor based on an in-fiber Mach–Zehnder interferometer with a magnetic fluid component

An ultrasensitive magnetic field sensor based on a compact in-fiber Mach–Zehnder interferometer(MZI) created in twin-core fiber(TCF) is proposed, and its performance is experimentally demonstrated. A section of TCF was spliced between two sections of standard single-mode fibers, and then a microchannel was drilled through one core of the TCF by means of femtosecond laser micromachining. The TCF with one microchannel was then immersed in a water-based Fe_3O_4 magnetic fluid(MF), forming a direct component of the light propagation path,and then sealed in a capillary tube, achieving a magnetic sensing element, which merges the advantages of an MZI with an MF. Experiments were conducted to investigate the magnetic response of the proposed sensor. The developed magnetic field sensor exhibits a linear response within a measurement range from 5 to 9.5 m T and an ultrahigh sensitivity of 20.8 nm/m T, which, to our best knowledge, is 2 orders of magnitude greater than other previously reported magnetic sensors. The proposed sensor is expected to offer significant potential for detecting weak magnetic fields.