This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micr...This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micrograph taken by a scanning electron microscope showsthe microstructures of the materials in detail. Scattering parameters of the waveguide sample holderfilled with the materials have been obtained over X band. The electromagnetic parameters computedfrom the measured S parameters show that the material with metallic hollow spheres has as highrelative permeability μ'_r as 19.0 with about 0.6 magnetic loss tangent over the whole bandwidth.Compared to the material with non-metallic spheres, the permeability μ'_r and the magnetic losstangent μ'_r increase greatly, while the permittivity remains lower than 1.8.展开更多
The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estim...The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.展开更多
A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1...A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1B - （ωε）^-1γJ is given. The divergenceless and irrotational splitting of dyadic Dirac 8 function and Fourier transformation are used to directly obtain the divergenceless and irrotational component of spectral-domain dyadic Green＇s functions in chiral media. This method avoids using the dyadic Green＇s function eigenfunction expansion technique. The method given here can be generalized to a source-free region and an achiral case.展开更多
With the rapid development of 5G communication and artificial intelligence(AI)technology,electromagnetic radiation pollution is emerging as a serious issue.Achieving both uniform dispersion and controllable loading of...With the rapid development of 5G communication and artificial intelligence(AI)technology,electromagnetic radiation pollution is emerging as a serious issue.Achieving both uniform dispersion and controllable loading of absorbers and obtaining functional wearable absorbers with high electromagnetic response are still considered great challenges.In this work,a flexible fiber-based absorber(VFT2h/MF/PPy)with a rich interfacial polarization relaxation was obtained by integrating heterostructures and performing nanostructure design and introducingπ-conjugated polymer components.Electrons migrated and redistributed between nanoparticles and nitrogen-carbon lattices with different electrostatic states.The formed heterogeneous interface promoted the electromagnetic attenuation response in the high-frequency region.More specifically,the effective absorption frequency bandwidth was up to 5.6 GHz(corresponds to the Ku-band with a matching thickness range up to 2.55–4.85 mm).Impressively,the abundant modification sites on the fiber surface adjusted the content and dispersion of the magnetic nanoparticles and enhanced the vector superposition effect generated by the structural distribution of the magnetic/electric fields.The introduction of dielectric components improved the interfacial polarization strength of the heterojunction surface and the synergistic effect of the dipolar polarization.The high-efficiency electromagnetic attenuation performance was attributed to multiple loss mechanisms.Our work provides a reference path for the microscopic regulation of the high-efficiency electromagnetic response mechanism of fiber-based flexible absorbing materials.展开更多
This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the o...This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the observation of geomagnetic pulsation events can detect the preseismic conductivity and structure anomalies of subsurface media more effectively than the conventional geomagnetic observations,especially the short-impending anomalies before earthquakes.Our research results have also indicated that the geomagnetic pulsation transfer function has obvious short-impending anomalies and typical anomaly forms before earthquakes.Using the proposed method,satisfactory prediction results have been obtained.展开更多
文摘This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micrograph taken by a scanning electron microscope showsthe microstructures of the materials in detail. Scattering parameters of the waveguide sample holderfilled with the materials have been obtained over X band. The electromagnetic parameters computedfrom the measured S parameters show that the material with metallic hollow spheres has as highrelative permeability μ'_r as 19.0 with about 0.6 magnetic loss tangent over the whole bandwidth.Compared to the material with non-metallic spheres, the permeability μ'_r and the magnetic losstangent μ'_r increase greatly, while the permittivity remains lower than 1.8.
文摘The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper.
基金Sponsored by the Natural Science Foundation of Liaoning Province (Grant No.20092146)
文摘A novel method of deriving the electromagnetic dyadic Green＇s functions in an unbounded, lossless, reciprocal and homogeneous chiral media described by the constitutive relations D = εE ＋ jγB and H = jγE ＋ μ^-1B - （ωε）^-1γJ is given. The divergenceless and irrotational splitting of dyadic Dirac 8 function and Fourier transformation are used to directly obtain the divergenceless and irrotational component of spectral-domain dyadic Green＇s functions in chiral media. This method avoids using the dyadic Green＇s function eigenfunction expansion technique. The method given here can be generalized to a source-free region and an achiral case.
基金financially supported by the National Key R&D Program of China(2023YFE0108300)the Natural Science Foundation of Jiangsu Province(BK20221336)+2 种基金Jiangsu Agricultural Science and Technology Independent Innovation Fund(CX(23)3060)Fujian Province Science and Technology Plan Project(2022N3013)Jiangxi Forestry Bureau Forestry Science and Technology Innovation Special Project(No.202240).
文摘With the rapid development of 5G communication and artificial intelligence(AI)technology,electromagnetic radiation pollution is emerging as a serious issue.Achieving both uniform dispersion and controllable loading of absorbers and obtaining functional wearable absorbers with high electromagnetic response are still considered great challenges.In this work,a flexible fiber-based absorber(VFT2h/MF/PPy)with a rich interfacial polarization relaxation was obtained by integrating heterostructures and performing nanostructure design and introducingπ-conjugated polymer components.Electrons migrated and redistributed between nanoparticles and nitrogen-carbon lattices with different electrostatic states.The formed heterogeneous interface promoted the electromagnetic attenuation response in the high-frequency region.More specifically,the effective absorption frequency bandwidth was up to 5.6 GHz(corresponds to the Ku-band with a matching thickness range up to 2.55–4.85 mm).Impressively,the abundant modification sites on the fiber surface adjusted the content and dispersion of the magnetic nanoparticles and enhanced the vector superposition effect generated by the structural distribution of the magnetic/electric fields.The introduction of dielectric components improved the interfacial polarization strength of the heterojunction surface and the synergistic effect of the dipolar polarization.The high-efficiency electromagnetic attenuation performance was attributed to multiple loss mechanisms.Our work provides a reference path for the microscopic regulation of the high-efficiency electromagnetic response mechanism of fiber-based flexible absorbing materials.
文摘This paper has presented a research on the method of using digitized data of geomagnetic pulsation observation to predict earthquakes and the research results.According to the theory of inductive magnetic effect,the observation of geomagnetic pulsation events can detect the preseismic conductivity and structure anomalies of subsurface media more effectively than the conventional geomagnetic observations,especially the short-impending anomalies before earthquakes.Our research results have also indicated that the geomagnetic pulsation transfer function has obvious short-impending anomalies and typical anomaly forms before earthquakes.Using the proposed method,satisfactory prediction results have been obtained.
