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Sample records for de-fg02-02er45964 electromagnetic properties

  1. Final Report, DOE Award Number DE-FG02-02ER45964, Electromagnetic Properties of Matter at X-ray Wavelengths

    SciTech Connect

    Smith, David Y

    2007-02-28

    We report results of a collaborative study of photon and charged-particle interactions with matter between the University of Vermont and Argonne and Brookhaven National Laboratories. A major goal was to extend the study of electromagnetic properties of selected materials to as wide a spectral range as possible. This broad approach discloses systematic trends not apparent in isolated measurements and exploits the power of dispersion analysis and sum-rule constraints. Emphasis was largely on UV and X-ray processes and capitalized on the wide range of photon energies available at NSLS. A key finding is that, under favorable circumstances, dispersion theory relates dispersive processes (e.g. refractive index, dielectric constant) to spectral moments of absorptive processes. This appears to be a new method in optics; it yields significant simplifications and provides a precise, model-independent characterization of optical materials. Problems addressed included a) x-ray magnetooptics; b) UV/soft-x-ray processes in insulators and their contribution to visible dispersion; c) demonstration of moments/dispersion analysis in glasses and applications to fiber-optic systems; d) the optical constants of silicon and their application to the stopping power of silicon for charged-particles. Results include; Resolution of a long-standing conflict over the relation between x-ray Faraday rotation and x-ray magnetic circular dichroism. Specifically, the Kramers-Kronig relations must be generalized to account for the breaking of time-reversal symmetry by magnetic fields. Experimental reports to the contrary were shown to be inconclusive. Reanalysis of x-ray Faraday rotation data supports the generalization; Demonstration that the optical properties of dielectrics in their region of transparency are determined by a series expansion in spectral moments of the dielectric’s infrared and ultraviolet absorption spectra. Application of this to silicate glasses clarifies the role of glass

  2. Electromagnetic properties of baryons

    SciTech Connect

    Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M.; Martin-Camalich, J.

    2011-10-21

    We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

  3. COHERENCE PROPERTIES OF ELECTROMAGNETIC RADIATION,

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , COHERENT SCATTERING), (*COHERENT SCATTERING, ELECTROMAGNETIC RADIATION ), LIGHT, INTERFERENCE, INTENSITY, STATISTICAL FUNCTIONS, QUANTUM THEORY, BOSONS, INTERFEROMETERS, CHINA

  4. Disentanglement of Electromagnetic Baryon Properties

    NASA Astrophysics Data System (ADS)

    Sadasivan, Daniel; Doring, Michael

    2017-01-01

    Through recent advances in experimental techniques, the precise extraction of the spectrum of baryonic resonances and their properties becomes possible. Helicity couplings at the resonance pole are fundamental parameters describing the electromagnetic properties of resonances and enabling the comparison of theoretical models with data. We have extracted them from experiments carried out at Jefferson Lab and other facilities using a multipole analysis within the Julich-Bonn framework. Special attention has been paid to the uncertainties and correlations of helicity couplings. Using the world data on the reaction γp -> ηp , we have calculated, for the first time, the covariance matrix. Our results are useful in several ways. They quantify uncertainties but also correlations of helicity couplings. Second, they can tell us quantitatively how useful a given polarization measurement is. Third, they can tell us how the measurement of a new observable would constrain and disentangle the resonance properties which could be helpful in the design of new experiments. Finally, on the subject of the missing resonance problem, model selection techniques and statistical tests allow us to quantify the significance of whether a resonance exists. Supported by NSF CAREER Grant No. PHY-1452055, NSF PIF Grant No. 1415459, by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, and by Research Center Julich through the HPC grant jikp07.

  5. Electromagnetic properties of massive neutrinos

    SciTech Connect

    Dobrynina, A. A. Mikheev, N. V.; Narynskaya, E. N.

    2013-10-15

    The vertex function for a virtual massive neutrino is calculated in the limit of soft real photons. A method based on employing the neutrino self-energy operator in a weak external electromagnetic field in the approximation linear in the field is developed in order to render this calculation of the vertex function convenient. It is shown that the electric charge and the electric dipole moment of the real neutrino are zero; only the magnetic moment is nonzero for massive neutrinos. A fourth-generation heavy neutrino of mass not less than half of the Z-boson mass is considered as a massive neutrino.

  6. Electromagnetic properties of material coated surfaces

    NASA Technical Reports Server (NTRS)

    Beard, L.; Berrie, J.; Burkholder, R.; Dominek, A.; Walton, E.; Wang, N.

    1989-01-01

    The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study.

  7. Dielectric property measurements in the Electromagnetic Properties Measurement Laboratory

    NASA Technical Reports Server (NTRS)

    Cravey, Robin L.; Tiemsin, Pacita I.; Bussell, Kerri; Dudley, Kenneth L.

    1995-01-01

    The capability to measure the dielectric properties of various materials has been developed in the Electromagnetic Properties Measurement Laboratory (EPML) of the Electromagnetics Research Branch (ERB). Two measurement techniques which have been implemented in the EPML to characterize materials are the dielectric probe and waveguide techniques. Several materials, including some for which the dielectric properties are well known, have been measured in an attempt to establish the capabilities of the EPML in determining dielectric properties. Brief descriptions of the two techniques are presented in this report, along with representative results obtained during these measurements.

  8. Statistical properties of ionospheric stimulated electromagnetic emissions

    NASA Astrophysics Data System (ADS)

    Karlsson, R. L.; Carozzi, T. D.; Norin, L.; Bergman, J. E. S.; Thidé, B.

    2006-08-01

    We have analysed the statistical properties of the stimulated electromagnetic emissions (SEE) spectral features in the steady state, reached after a long period of continuous HF pumping of the ionosphere in experiments performed at the Sura ionospheric radio research facility in Russia. Using a digital filter bank method, we have been able to analyse complex valued signals within narrow frequency bands. Each of the SEE spectral features are thereby separated into a number of narrow spectral components. Statistical tests were performed for all these spectral components and the distributions of the spectral amplitudes and phases were evaluated. Also, a test for sinusoidal components was performed. These tests showed that all observed SEE features were indistinguishable from coloured Gaussian noise. The test results exclude that the SEE features can be the result of a single isolated coherent process, but does not rule out that there could be many statistically independent parametric wave-wave processes taking place simultaneously at various parts of the HF-pumped ionosphere, as long as the superposition from all these is incoherent. Furthermore, from the test results, we cannot exclude the possibility that the waveforms of some, or all, of the SEE features may be chaotic.

  9. Metamaterial Composites with Tunable Electromagnetic Properties

    NASA Astrophysics Data System (ADS)

    Wheeland, Sara Ruth

    A broadening application range has increased demand for advanced RF control. Recent research has identified several metamaterials to provide this control. This work seeks to expand this idea through several novel metamaterials with enhanced electromagnetic properties. First copper wires braided with Kevlar and nylon to form conductive coils are woven among structural fiber to create a fabric. This yielded a composite with all coils possessing the same handedness, producing a chiral material. The measured scattering parameters showed considerable chirality within the 5.5-8GHz frequency band, agreeing with simulation results. Electronic chirality tuning is investigated by integrating varactor diodes into an array of helical elements on a printed circuit board. Applying a varied reverse bias voltage across the sample effectively tunes the chiral behavior of the material. The measurements demonstrate the feasibility of creating a rigid helix composite with tuned chirality in the 5.5-12.4GHz frequency band. Chirality can be further tuned mechanically through the deformation of an array of conductive coils. Parallel, metallic helices embedded in a polyurethane matrix are subjected to mechanical stretching for pitch adjustment. This change in pitch directly affects the overall chirality of the composite. Repeatable elastic deformation is achieved up to 50% axial strain. Over the 5.5-12.5GHz frequency range, an increase of 30% axial strain yields an ˜18% change in axial chirality. Hyperbolic microwave focusing is explored through an indefinite medium with anisotropic permittivity. An array of 12-gauge brass wires is embedded in Styrofoam and scanned over the 7-9GHz frequency band to establish focusing patterns. A soft-focusing spot is observed at 7.6GHz with a relative gain of ˜7dB over averaged background. Applying an axial refractive gradient to a coil composite creates a lens capable of fine adjustment in the microwave range. The gradient required to achieve sharp

  10. Electromagnetic properties of ice coated surfaces

    NASA Technical Reports Server (NTRS)

    Dominek, A.; Walton, E.; Wang, N.; Beard, L.

    1989-01-01

    The electromagnetic scattering from ice coated structures is examined. The influence of ice is shown from a measurement standpoint and related to a simple analytical model. A hardware system for the realistic measurement of ice coated structures is also being developed to use in an existing NASA Lewis icing tunnel. Presently, initial measurements have been performed with a simulated tunnel to aid in the development.

  11. Electromagnetic absorption properties of spacecraft and space debris

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Santoni, F.; Giusti, A.; Delfini, A.; Pastore, R.; Vricella, A.; Albano, M.; Arena, L.; Piergentili, F.; Marchetti, M.

    2017-04-01

    Aim of the work is to present a method to evaluate the electromagnetic absorption properties of spacecraft and space debris. For these objects, the radar detection ability depends mainly on volume, shape, materials type and other electromagnetic reflecting behaviour of spacecraft surface components, such as antennas or thermal blankets, and of metallic components in space debris. The higher the electromagnetic reflection coefficient of such parts, the greater the radar detection possibility. In this research an electromagnetic reverberation chamber is used to measure the absorption cross section (ACS) of four objects which may represent space structure operating components as well as examples of space debris: a small satellite, a composite antenna dish, a Thermal Protection System (TPS) tile and a carbon-based composite missile shell. The ACS mainly depends on geometrical characteristics like apertures, face numbers and bulk porosity, as well as on the type of the material itself. The ACS, which is an electromagnetic measurement, is expressed in squared meters and thus can be compared with the objects geometrical cross section. A small ACS means a quite electromagnetic reflective tendency, which is beneficial for radar observations; on the contrary, high values of ACS indicate a strong absorption of the electromagnetic field, which in turn can result a critical hindering of radar tracking.

  12. Electromagnetic properties of the early universe

    SciTech Connect

    Takahashi, Keitaro; Ichiki, Kiyotomo; Sugiyama, Naoshi

    2008-06-15

    Detailed physical processes of magnetic field generation from density fluctuations in the prerecombination era are studied. Solving Maxwell equations and the generalized Ohm's law, the evolutions of the net charge density, the electric current, and the electromagnetic field are solved. Unlike most of the previous works, we treat electrons and photons as separate components under the assumption of tight coupling. We find that generation of the magnetic field due to density fluctuations takes place only from the second order of both perturbation theory and the tight coupling approximation.

  13. Aerodynamic and Electromagnetic Properties of Plasmas.

    DTIC Science & Technology

    1981-10-01

    function theorem on topological spaces . To appear in Applicable Mathematics. 50. Shui-Hung Hou, On property (Q) and other semicontinuity properties... topological spaces . The author proves here Filippov type implicit function theorems for Carathgodory mappings in general topological spaces . The author...separation in topological spaces . Connection between separation properties of spaces and measurability of graphs of multifunctions are established. - 11

  14. Study on the electromagnetic properties of a coated radar absorbent

    NASA Astrophysics Data System (ADS)

    Zhang, Shuan-Qin

    2012-06-01

    The sol-gel method is used to fabricate Fe crystalline powders coated with SiO2. By controlling the molar ratio R of diluted water to tetraethoxysilane (TEOS), Fe powders coated with SiO2 with different morphological characteristics are fabricated. The influence of the core diameter on electromagnetic parameters is investigated. The effect of the amount of the coating material SiO2 on electromagnetic parameters is given. Radar wave absorbing properties of Fe coated with SiO2 and TiO2 respectively are compared.

  15. Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-07-01

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.

  16. Electromagnetic wave absorbing properties of amorphous carbon nanotubes.

    PubMed

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-07-10

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.

  17. Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

    PubMed Central

    Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

    2014-01-01

    Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7–50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was −25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at −10 dB was up to 5.8 GHz within the frequency range of 2–18 GHz. PMID:25007783

  18. Nanoelectromagnetics: circuit and electromagnetic properties of carbon nanotubes.

    PubMed

    Rutherglen, Chris; Burke, Peter

    2009-04-01

    This Review presents a discussion of the electromagnetic properties of nanoscale electrical conductors, which are quantum mechanical one-dimensional systems. Of these, carbon nanotubes are the most technologically advanced example, and are discussed mainly in this paper. The properties of such systems as transmission electron microscopy waveguides for on-chip signal propagation and also the radiation properties of such systems are discussed. This work is primarily aimed at microwave, nanometer-wave, and THz electronics. However, the use of nanotubes as antennas in the IR and optical frequency range is not precluded on first principles and remains an open research area.

  19. Controlling the Casimir force via the electromagnetic properties of materials

    SciTech Connect

    Yang Yaping; Chen Hong; Zeng Ran; Zhu Shiyao; Zubairy, M. Suhail

    2010-02-15

    The control of the Casimir force between two parallel plates can be achieved through adjusting the frequency-dependent electromagnetic properties of materials of the two plates. We show that, for different plate separations, the main contribution to the Casimir force comes from different frequency regions: For smaller (larger) separation, it comes from the higher (lower) frequency region. When the separation of the plates increases, the Casimir force can vary from attractive to repulsive and/or vice versa, by selecting the two plates with suitable electromagnetic properties. We discuss how a restoring Casimir force, which varies from repulsive to attractive by increasing the separation, can be realized and that the stable equilibrium is formed at zero Casimir force.

  20. Electromagnetic absorption properties of graphene/Fe nanocomposites

    SciTech Connect

    Chen, Yujin; Lei, Zhenyu; Wu, Hongyu; Zhu, Chunling; Gao, Peng; Ouyang, Qiuyun; Qi, Li-Hong; Qin, Wei

    2013-09-01

    Graphical abstract: - Highlights: • Graphene/Fe nanocomposites were prepared by a facile and green method. • 10 nm Fe nanoparticles were uniformly dispersed over the surface of the graphene sheets. • The nanocomposites exhibited strong electromagnetic wave absorption properties. - Abstract: Graphene (G)/Fe nanocomposites with ferromagnetic properties at room temperature were fabricated by a facile and green method. Transmission electron microscope (TEM) and atomic force microscopy (AFM) amylases reveal that the α-Fe nanoparticles with a diameter of only about 10 nm were uniformly dispersed over the surface of the graphene sheets. Compared with other magnetic materials and the graphene, the nanocomposites exhibited significantly enhanced electromagnetic absorption properties. The maximum reflection loss to electromagnetic wave was up to −31.5 dB at a frequency of 14.2 GHz for G/Fe nanocomposites with a thickness of 2.5 mm. Importantly, the addition of the nanocomposites is only about 20 wt.% in the matrix. The enhanced mechanism is discussed and it is related to high surface areas of G/Fe nanocomposites, interfacial polarizations between graphene and iron, synergetic effect and efficient dispersity of magnetic NPs.

  1. Topologically nontrivial Fermi regions and their novel electromagnetic response properties

    NASA Astrophysics Data System (ADS)

    Lee, Ching Hua; Zhang, Xiao

    In the last decade, there has been a surge of interest in the application of topology to condensed matter physics. So far, most studies have been concerned with the novel properties that arise due to nontrivial band topology, i.e Quantum Anomalous Hall and Z2 topological insulators (TIs). In this talk, I shall describe another context where nontrivial topology also leads to interesting, measurable effects. Within the semi-classical Boltzmann approach, it can be shown that a topologically nontrivial Fermi sea region generically exhibits a non-monotonic nonlinear electromagnetic response in the limit of low chemical potential. Such topologically nontrivial regions of filled states can arise in experimentally realized TI heterostructures or materials with large Rashba splitting, i.e. BiTeI, where the Fermi sea is not simply connected. A non-monotonic electromagnetic response implies regimes of negative differential resistance, which have important applications in technologies involving microwave generation, like motion sensing and radio astronomy. We hope that nontrivial Fermi sea topology will hence provide another route for the realization of such technologies.

  2. Electromagnetic properties of the Beryllium-11 nucleus in Halo EFT

    NASA Astrophysics Data System (ADS)

    Phillips, D. R.; Hammer, H.-W.

    2010-04-01

    We compute electromagnetic properties of the Beryllium-11 nucleus using an effective field theory that exploits the separation of scales in this halo system. We fix the parameters of the EFT from measured data on levels and scattering lengths in the 10Be plus neutron system. We then obtain predictions for the B(E1) strength of the 1/2+ to 1/2- transition in the 11Be nucleus. We also compute the charge radius of the ground state of 11Be. Agreement with experiment within the expected accuracy of a leading-order computation in this EFT is obtained. We also indicate how higher-order corrections that affect both s-wave and p-wave 10 Be-neutron interactions will affect our results.

  3. Electromagnetic Properties of Impact-Generated Plasma, Vapor and Debris

    SciTech Connect

    Crawford, D.A.; Schultz, P.H.

    1998-11-02

    Plasma, vapor and debris associated with an impact or explosive event have been demonstrated in the laboratory to produce radiofrequency and optical electromagnetic emissions that can be diagnostic of the event. Such effects could potentially interfere with communications or remote sensing equipment if an impact occurred, for example, on a satellite. More seriously, impact generated plasma could end the life of a satellite by mechanisms that are not well understood and not normally taken into account in satellite design. For example, arc/discharge phenomena resulting from highly conductive plasma acting as a current path across normally shielded circuits may have contributed to the loss of the Olympus experimental communications satellite on August 11, 1993. The possibility of significant storm activity during the Leonid meteor showers of November 1998, 1999 and 2000 (impact velocity, 72 km/s) has heightened awareness of potential vulnerabilities from hypervelocity electromagnetic effects to orbital assets. The concern is justified. The amount of plasma, electrostatic charge and the magnitude of the resulting currents and electric fields scale nearly as the cube of the impact velocity. Even for microscopic Leonid impacts, the amount of plasma approaches levels that could be dangerous to spacecraft electronics. The degree of charge separation that occurs during hypervelocity impacts scales linearly with impactor mass. The resulting magnetic fields increase linearly with impactor radius and could play a significant role in our understanding of the paleomagnetism of planetary surfaces. The electromagnetic properties of plasma produced by hypervelocity impact have been exploited by researchers as a diagnostic tool, invoked to potentially explain the magnetically jumbled state of the lunar surface and blamed for the loss of the Olympus experimental communications satellite. The production of plasma in and around an impact event can lead to several effects: (1) the

  4. Electromagnetic shielding effectiveness and mechanical properties of graphite-based polymeric films

    NASA Astrophysics Data System (ADS)

    Kenanakis, G.; Vasilopoulos, K. C.; Viskadourakis, Z.; Barkoula, N.-M.; Anastasiadis, S. H.; Kafesaki, M.; Economou, E. N.; Soukoulis, C. M.

    2016-09-01

    Modern electronics have nowadays evolved to offer highly sophisticated devices. It is not rare; however, their operation can be affected or even hindered by the surrounding electromagnetic radiation. In order to provide protection from undesired external electromagnetic sources and to ensure their unaffected performance, electromagnetic shielding is thus necessary. In this work, both the electromagnetic and mechanical properties of graphite-based polymeric films are studied. The investigated films show efficient electromagnetic shielding performance along with good mechanical stiffness for a certain graphite concentration. To the best of our knowledge, the present study illustrates for the first time both the electromagnetic shielding and mechanical properties of the polymer composite samples containing graphite filler at such high concentrations (namely 60-70 %). Our findings indicate that these materials can serve as potential candidates for several electronics applications.

  5. Investigation of mechanical properties of pavement through electromagnetic techniques

    NASA Astrophysics Data System (ADS)

    Benedetto, Andrea; Tosti, Fabio; D'Amico, Fabrizio

    2014-05-01

    Ground-penetrating radar (GPR) is considered as one of the most flexible geophysical tools that can be effectively and efficiently used in many different applications. In the field of pavement engineering, GPR can cover a wide range of uses, spanning from physical to geometrical inspections of pavements. Traditionally, such inferred information are integrated with mechanical measurements from other traditional (e.g. plate bearing test) or non-destructive (e.g. falling weight deflectometer) techniques, thereby resulting, respectively, in time-consuming and low-significant measurements, or in a high use of technological resources. In this regard, the new challenge of retrieving mechanical properties of road pavements and materials from electromagnetic measurements could represent a further step towards a greater saving of economic resources. As far as concerns unpaved and bound layers it is well-known that strength and deformation properties are mostly affected, respectively, by inter-particle friction and cohesion of soil particles and aggregates, and by bitumen adhesion, whose variability is expressed by the Young modulus of elasticity. In that respect, by assuming a relationship between electromagnetic response (e.g. signal amplitudes) and bulk density of materials, a reasonable correlation between mechanical and electric properties of substructure is therefore expected. In such framework, a pulse GPR system with ground-coupled antennae, 600 MHz and 1600 MHz centre frequencies was used over a 4-m×30-m test site composed by a flexible pavement structure. The horizontal sampling resolution amounted to 2.4×10-2 m. A square regular grid mesh of 836 nodes with a 0.40-m spacing between the GPR acquisition tracks was surveyed. Accordingly, a light falling weight deflectometer (LFWD) was used for measuring the elastic modulus of pavement at each node. The setup of such instrument consisted of a 10-kg falling mass and a 100-mm loading plate so that the influence domain

  6. Notebook on Electromagnetic Properties of Composite Materials Below 1 GHz.

    DTIC Science & Technology

    1981-09-01

    Electrojaanet e Pulse (NEMP). T-" DD 1473 "EsIeON GO INov so is 69SOLeTEs 0,CURT, CLA,,oICATIO OF 114o, PAGE (Me, Do, ,,., NOTEBOOK ON ELECTROMAGNETIC...Composites, RADC-TR-76-206, July 1976 6. R. Force, P. Green et. al., Investigation on Effects of Electromagnetic Energy on Advanced Composite Aircraft...Electromagnetic Pulse (EMP) Environment, The Boeing Co. 5. F. Force, et. al., Investigation of Effects of Electromagnetic Energy on Advanced Composite

  7. Measurement of Electromagnetic Properties of Lightning with 10 Nanosecond Resolution

    NASA Technical Reports Server (NTRS)

    Baum, C. E.; Breen, E. L.; Oneill, J. P.; Moore, C. B.; Hall, D. L.

    1980-01-01

    Electromagnetic data recorded from lightning strikes are presented. The data analysis reveals general characteristics of fast electromagnetic fields measured at the ground including rise times, amplitudes, and time patterns. A look at the electromagnetic structure of lightning shows that the shortest rise times in the vicinity of 30 ns are associated with leader leader streamers. Lightning location is based on electromagnetic field characteristics and is compared to a nearby sky camera. The fields from both leaders and return strokes were measured and are discussed. The data were obtained during 1978 and 1979 from lightning strikes occuring within 5 kilometers of an underground metal instrumentation room located on South Baldy peak near Langmuir Laboratory, New Mexico. The computer controlled instrumentation consisted of sensors previously used for measuring the nuclear electromagnetic pulse (EMP) and analog-digital recorders with 10 ns sampling, 256 levels of resolution, and 2 kilobytes of internal memory.

  8. Synthesis and Properties of Polymer Nanocomposites with Tunable Electromagnetic Response

    NASA Astrophysics Data System (ADS)

    Stojak, Kristen L.

    Multifunctional polymer nanocomposites (PNCs) are attractive for the design of tunable RF and microwave components such as flexible electronics, attenuators, and antennas due to cost-effectiveness and durability of polymeric matrices. In this work, three separate PNCs were synthesized. Magnetite (Fe 3O4) and cobalt ferrite (CFO) nanoparticles, synthesized by thermal decomposition, were used as PNC fillers. Polymers used in this work were a commercial polymer provided by the Rogers Corporation (RP) and polyvinylidene fluoride (PVDF). PNCs in this thesis consist of Fe3O 4 in RP, CFO in RP, and Fe3O4 in PVDF. Characterization techniques for determining morphology of the nanoparticles, and their resulting PNCs, include x-ray diffraction, transmission electron microscopy and magnetometry. All magnetometry measurements were taken using a Quantum Design Physical Property Measurement System with a superconducting magnet. Temperature and external magnetic field magnetization measurements revealed that all samples exhibit superparamagnetic behavior at room temperature. Blocking temperature, coercivity and reduced remnant magnetization do not vary with concentration. Tunable saturation magnetization, based on nanoparticle loading, was observed across all PNCs, regardless of polymer or nanoparticle choice, indicating that this is an inherent property in all similar PNC materials. Tunability studies of the magneto-dielectric PNCs were carried out by adding the PNC to cavity and microstrip linear resonator devices, and passing frequencies of 1-6 GHz through them in the presence of transverse external magnetic fields of up to 4.5 kOe, provided by an electromagnet. Microwave characteristics were extracted from scattering parameters of the PNCs. In all cases, losses were reduced, quality factor was increased, and tunability of the resonance frequency was demonstrated. Strong magnetic field dependence was observed across all samples measured in this study.

  9. Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials

    NASA Astrophysics Data System (ADS)

    Savinov, V.; Fedotov, V. A.; Zheludev, N. I.

    2014-05-01

    The toroidal dipole is a peculiar electromagnetic excitation that can not be presented in terms of standard electric and magnetic multipoles. A static toroidal dipole has been shown to lead to violation of parity in atomic spectra and many other unusual electromagnetic phenomena. The existence of electromagnetic resonances of toroidal nature was experimentally demonstrated only recently, first in the microwave metamaterials, and then at optical frequencies, where they could be important in spectroscopy analysis of a wide class of media with constituents of toroidal symmetry, such as complex organic molecules, fullerenes, bacteriophages, etc. Despite the experimental progress in studying toroidal resonances, no direct link has yet been established between microscopic toroidal excitations and macroscopic scattering characteristics of the medium. To address this essential gap in the electromagnetic theory, we have developed an analytical approach for calculating the transmissivity and reflectivity of thin slabs of materials that exhibit toroidal dipolar excitations.

  10. Effects of microstructure and filling ratio on electromagnetic properties of Co microspheres

    NASA Astrophysics Data System (ADS)

    Chen, N.; Jiang, J. T.; Yuan, Y.; Liu, C.; Xu, C. Y.; Zhen, L.

    2017-01-01

    Cobalt microspheres with diameters of 1.5-3.5 μm were synthesized by a liquid phase reduction method. The effects of hydrogen annealing on microstructure evolution and electromagnetic properties of Co microspheres were investigated. The influence of filling ratio on the electromagnetic properties of specimens containing Co microspheres as fillers was also examined. The results indicated that the annealing leads to increase in Co microspheres' permittivity as the improved conductivity that developed during annealing contributes to enhanced dielectric relaxation. High filling ratio is found to be favorable for achieving high electromagnetic properties and thus higher electromagnetic absorbing performances, which is of technical significant for application in low frequency band. Coatings containing 30, 45 and 50 vol% Co particles as fillers present excellent EMA performance, even very thin thickness is applied. High electromagnetic wave absorbing efficiency of -10 dB was observed at thickness of 1.5 mm in C band and the electromagnetic wave absorption bandwidth reaches up to 6.3 GHz (6.7-13 GHz) when the filling volume is 45 vol%.

  11. Dispersion properties of compressional electromagnetic waves in quantum dusty magnetoplasmas

    SciTech Connect

    Ali, S.; Shukla, P.K.

    2006-05-15

    A new dispersion relation for low-frequency compressional electromagnetic waves is derived by employing quantum magnetohydrodynamic model and Maxwell equations in cold quantum dusty magnetoplasmas. The latter is composed of inertialess electrons, mobile ions, and immobile charged dust particulates. The dispersion relation for the low-frequency compressional electromagnetic modes is further analyzed for the waves propagating parallel, perpendicular, and oblique to the external magnetic field direction. It is found theoretically and numerically that the quantum parameter {alpha}{sub q}=(n{sub i0}/n{sub e0})({Dirac_h}/2{pi}){sup 2}/(4m{sub e}m{sub i}) affects the real angular frequencies and the phase speeds of the compressional electromagnetic modes. Here, n{sub i0} (n{sub e0}) is the equilibrium number density of the ions (electrons), m{sub e} (m{sub i}) is the electron (ion) mass, and ({Dirac_h}/2{pi}) is the Plank constant divided by 2{pi}.

  12. Electromagnetic properties of metal-dielectric media and their applications

    NASA Astrophysics Data System (ADS)

    Animilli, Shravan Rakesh

    The main objective of this dissertation is to investigate nano-structured random composite materials, which exhibit anomalous phenomena, such as the extraordinary enhancements of linear and non-linear optical processes due to excitation of collective electronic states, surface plasmons (SP). The main goal is to develop a time and memory efficient novel numerical method to study the properties of these random media in three dimensions (3D) by utilization of multi core processing and packages such as MPI for parallel execution. The developed numerical studies are then utilized to provide a comprehensive characterization and optimization of a surface plasmon enhanced solar cell (SPESC) and to serve as a test bed for enhanced bio and chemical sensing. In this context, this thesis work develops an efficient and exact numerical algorithm here referred to as Block Elimination Method (BE) which provides the unique capability of modeling extremely large scale composite materials (with up to 1 million strongly interacting metal or dielectric particles). This capability is crucial in order to study the electromagnetic response of large scale inhomogeneous (fractal) films and bulk composites at critical concentrations (percolation). The developed numerical method is used to accurately estimate parameters that describe the composite materials, including the effective conductivity and correlation length scaling exponents, as well as density of states and localization length exponents at the band center. This works reveals, for a first time, a unique de-localization mechanism that plays an important role in the excitation of charge-density waves, i.e. surface plasmons (SP), in metal-dielectric composites. It also shows that in 3D metal-dielectric percolation systems the local fields distribution function for frequencies close to the single particle plasmon resonance is log-normal which is a signature of a metal-dielectric phase transition manifested in the optical response of the

  13. ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY

    NASA Astrophysics Data System (ADS)

    Tian, N.; Fan, X. D.; Wang, J. W.; You, C. Y.; Lu, Z. X.; Ge, L. L.

    2013-07-01

    High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α-Fe possesses a high saturation magnetization. Fe-B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α-Fe simultaneously. In this work, we made nanocrystalline powders of Fe82B17Cu1, mainly consisting of α-Fe and Fe2B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe82B17Cu1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.

  14. Electromagnetic field properties in the vicinity of a massive wormhole

    SciTech Connect

    Novikov, I. D.; Shatskiy, A. A.

    2011-12-15

    It is proved that not only massless but also traversable massive wormholes can have electromagnetic 'hair.' An analysis is also presented of the passage from a traversable wormhole to the limit of a Reissner-Nordstroem black hole, with the corresponding disappearance of 'hair.' A general method is developed for solving stationary axisymmetric Maxwell's equations in the field of a massive, spherically symmetric wormhole. As a particular example of application of the method, a solution is found to the axisymmetric magnetostatic problem for a current loop in the field of the Bronnikov-Ellis-Morris-Thorne wormhole.

  15. Fabrication and electromagnetic properties of fe nanofibers composites

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Bok; Hong, Sung-Jin; Yi, Jin-Woo; Lee, Sang-Kwan; Choa, Yong-Ho; Kim, Jin-Bong

    2012-02-01

    In order to develop electromagnetic (EM) wave absorbing materials in the giga-hertz (GHz) frequency range, Fe nanofibers have been prepared by multi-nozzle electrospinning process (ESP) and heat treatments. The effects of applied voltage and feed rate on the morphology of electrospun PVP/Fe salt nanofibers have been studied in the electrospinning process. The average diameter and the standard deviation of electrospun nanofibers tend to decrease with the increase of the applied voltage and the decrease of the feed rate, respectively. Through the heat treatments of calcination and H2 reduction, as-spun PVP/Fe salt has been stepwise transformed into Fe2O3, Fe3O4, and Fe phases. To evaluate the EM characteristic of the prepared Fe nanofibers, epoxy matrix composites containing Fe nanofibers of 10 and 30 wt% have been fabricated. The Fe nanofibers have improved the EM characteristics of composites as compared to those of nano-sized metallic particles.

  16. Electro-magnetically controlled acoustic metamaterials with adaptive properties.

    PubMed

    Malinovsky, Vladimir S; Donskoy, Dimitri M

    2012-10-01

    A design of actively controlled metamaterial is proposed and discussed. The metamaterial consists of layers of electrically charged nano or micro particles exposed to external magnetic field. The particles are also attached to compliant layers in a way that the designed structure exhibits two resonances: mechanical spring-mass resonance and electro-magnetic cyclotron resonance. It is shown that if the cyclotron frequency is greater than the mechanical resonance frequency, the designed structure could be highly attenuative (40-60 dB) for vibration and sound waves in very broad frequency range even for wavelength much greater than the thickness of the metamaterial. The approach opens up wide range of opportunities for design of adaptively controlled acoustic metamaterials by controlling magnetic field and/or electrical charges.

  17. Composite Material Aircraft Electromagnetic Properties and Design Guidelines

    DTIC Science & Technology

    1981-01-01

    external RP sources. In this section, the mechanisms for interference and damage of semiconductor devices by RF signals is discussed in detail...Laser, Nuclear Thermal Radiation and Particle Beam Threat 2-28 2.3 References 2-31 3.0 Composition, Fabrication and Mechanical Properties of Composite...3.3 Mechanical Properties 3-9 3.3.1 Composite Fiber Properties 3-9 3.3.2 Compositia Matrix Properties 3-12 3.3.3 Single Laminate Composite Properties

  18. Electromagnetic and microwave-absorbing properties of magnetic nickel ferrite nanocrystals.

    PubMed

    Zhu, Weimo; Wang, Lei; Zhao, Rui; Ren, Jiawen; Lu, Guanzhong; Wang, Yanqin

    2011-07-01

    The electromagnetic and microwave absorbing properties of nickel ferrite nanocrystals were investigated for the first time. There were two frequencies corresponding to the maximum reflection loss in a wide thickness range from 3.0 to 5.0 mm, which may be bought by the nanosize effect and the good crystallization of the nanocrystals.

  19. Nondestructive identification of material properties of fibre concrete: A time-harmonic electromagnetic field

    NASA Astrophysics Data System (ADS)

    Hobst, L.; Bílek, P.

    2016-06-01

    The magnetic approach to the identification of mechanical properties of fibre concrete, using permanent magnets, has its electromagnetic alternative, more suitable to the nondestructive detection of orientation of fibres, in addition to the evaluation of their volume fraction. This paper sketches related approaches to both experimental settings and computational simulations.

  20. Changes in electromagnetic properties of a low-alloy steel caused by neutron irradiation

    SciTech Connect

    Goto, Toru; Kamimura, Takeo; Kumano, Shintaro; Takeuchi, Iwao; Maeda, Noriyoshi; Yamaguchi, Atsunori

    1999-10-01

    In order to develop a method for the nondestructive evaluation of material deterioration in nuclear pressure vessels, changes in the electromagnetic properties of the low-alloy steel A533B, Class 1 and its weld metal caused by neutron irradiation up to {approximately}3 {times} 10{sup 23} n/m{sup 2} of neutron fluence at 561 K were measured. Electrical resistance, coercivity and Barkhausen noise were selected as the electromagnetic properties to measure. It was found that decreases of several percent in the readings of electrical resistance and coercivity, and an increase of several percent in the Barkhausen noise occurred due to neutron irradiation. Good correlations between the changes in the electromagnetic properties and those in the mechanical properties were confirmed. Furthermore, an equation using the results of the three tests was found to estimate well the transition temperature and yield strength. From this, the authors conclude that the electromagnetic tests have potential as methods for nondestructive evaluation of material deterioration in the reactor vessels of nuclear power plants.

  1. Electromagnetic properties of Bi-2223/Ag concentric tapes

    SciTech Connect

    Majoros, M.; Polak, M.; Kvitkovic, J.; Suchon, D.; Martini, L.; Ottoboni, V.; Zannella, S.

    1996-07-01

    It is well established that near the silver interface highly textured Bi-2223 layers compared to the inner ceramic core may be obtained. Thus Bi-2223 multilayered concentric tapes with silver matrix are very promising in increasing transport critical current densities. In the present work the authors report on the electromagnetic characterization of short tapes having in their cross-section a very thin HTS flattened ring with Ag inside and outside of it. The samples were prepared by the powder in tube method and have self-field critical current densities J{sub c} of the order of 3 {times} 10{sup 4} A/cm{sup 2} at 77 K. Transport and SQUID magnetization measurements revealed weak link nature of the samples in low magnetic fields. Large transport J{sub c}(B) hysteresis was observed at 4.2 K and magnetic fields up to 20 T. Magnetic field profiles measurements with miniature Hall sensors are in qualitative accordance with model calculations supposing homogeneous current density distribution across the superconducting core.

  2. Electromagnetic method for analyzing the property of steel casing

    SciTech Connect

    Lee, K.H.; Kim, H.J.; Song, Y.

    1998-02-01

    It has been shown that electromagnetic (EM) imaging, in particular in borehole applications, can be effective in characterizing and monitoring subsurface processes involved in improved oil recovery operations and production management. In this report the authors present an innovative EM method for extracting information about a steel casing in terms of its electrical conductivity, magnetic permeability, and the casing thickness. The method is based on accurate evaluation of magnetic fields near the transmitting loop in a steel-cased borehole, and the least squares inversion of thus measured data. The need to make measurements close to the source stems from the two related considerations. One reason is that by making measurements close to the transmitter one can keep the formation response from entering the measurement to a minimum. The other reason concerns with the practical consideration involved in fabricating a borehole tool. The measurement accuracy in terms of PPM to the primary field can best be achieved when the transmitter and receiver are close to each other. To facilitate this requirement one can consider a single loop acting as the source and the receiver operating in time domain, or a closely coupled frequency-domain system with the source-receiver separation of just a few inches apart. Results are discussed.

  3. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhou, Ting-dong

    2017-03-01

    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  4. Double negative electromagnetic property of granular composite materials in the microwave range

    NASA Astrophysics Data System (ADS)

    Tsutaoka, Takanori; Kasagi, Teruhiro; Yamamoto, Shinichiro; Hatakeyama, Kenichi

    2015-06-01

    The double negative (DNG) electromagnetic property, i.e. the simultaneous negative permittivity and permeability, of granular composite materials has been studied in the microwave frequency range. The negative permittivity spectrum can be realized by the low frequency plasma oscillation which is generated in the percolated metal particle chain as well as the dielectric resonance of the induced dipole in the isolated metal particle clusters. Meanwhile, the negative permeability spectrum can be obtained by the magnetic resonance of the embedded ferromagnetic particles in the granular composite structure. By combining these negative electromagnetic properties, the DNG characteristics can be produced in the granular composite material. The DNG properties of the Cu/Yttrium Iron Garnet (Cu/YIG) granular composite materials under external magnetic field will be presented; the negative refractive index of the Cu/YIG composite material will also be discussed.

  5. Electromagnetic properties of ice-coated iron whiskers

    NASA Astrophysics Data System (ADS)

    Jazbi, B.; Hoyle, F.; Wickramasinghe, N. C.

    1990-12-01

    In their recent papers, Hoyle and Wickramasinghe (1988, 1989) and Hoyle et al. (1990) argued that iron whiskers condensing in supernovae could be expelled from entire galaxies to become dispersed over cosmological distance scales and to generate a cosmic microwave background by thermalizing optical and NIR radiation from stellar sources. In this paper, the effect of H2O-ice mantles on infinitely long cylindrical metallic whiskers is investigated using the rigorous Kerker-Matijevic (1961) formulae. It is shown that ice coating does not significantly alter the cosmologically relevant properties of uncoated metallic whiskers.

  6. Effect of nitrogen doping on the electromagnetic properties of carbon nanotube-based composites

    NASA Astrophysics Data System (ADS)

    Kanygin, M. A.; Sedelnikova, O. V.; Asanov, I. P.; Bulusheva, L. G.; Okotrub, A. V.; Kuzhir, P. P.; Plyushch, A. O.; Maksimenko, S. A.; Lapko, K. N.; Sokol, A. A.; Ivashkevich, O. A.; Lambin, Ph.

    2013-04-01

    Nitrogen-doped and pure carbon nanotube (CNT) based composites were fabricated for investigating their dielectric properties in static regime as well as electromagnetic response properties in microwave frequency range (Ka-band). Two classes of host matrix—polystyrene and phosphate unfired ceramics—have been used for composites fabrication. The study reveals miscellaneous effect of nitrogen doping on the dielectric permittivity, dc conductivity and electromagnetic interference shielding efficiency of CNT-based composites, produced with both polymer and ceramic matrices. The high-frequency polarizability, estimated for different-length CNTs, and static polarizability, calculated for nitrogen-containing CNT models using a quantum-chemical approach, show that this effect results from a decrease of the nanotube defect-free-length and deterioration of the polarizability with incorporation of nitrogen in pyridinic form.

  7. Numerical studies on the electromagnetic properties of the nonlinear Lorentz Computational model for the dielectric media

    SciTech Connect

    Abe, H.; Okuda, H.

    1994-06-01

    We study linear and nonlinear properties of a new computer simulation model developed to study the propagation of electromagnetic waves in a dielectric medium in the linear and nonlinear regimes. The model is constructed by combining a microscopic model used in the semi-classical approximation for the dielectric media and the particle model developed for the plasma simulations. It is shown that the model may be useful for studying linear and nonlinear wave propagation in the dielectric media.

  8. Study on the characteristics of magneto-sensitive electromagnetic wave-absorbing properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Yang, Pingan; Fu, Jie; Liu, Shuzhi; Qi, Song

    2016-08-01

    Magnetorheological (MR) materials are a class of materials whose mechanical and electrical properties can be reversible controlled by the magnetic field. In this study, we pioneered research on the effect of a uniform magnetic field with different strengths and directions on the microwave-absorbing properties of magnetorheological elastomers (MREs), in which the ferromagnetic particles are flower-like carbonyl iron powders (CIPs) prepared by an in situ reduction method. The electromagnetic (EM) absorbing properties of the composites have been analyzed by vector network analysis with the coaxial reflection/transmission technique. Under the magnetic field, the columnar or chainlike structures were formed, which allows EM waves to penetrate. Meanwhile, stronger Debye dipolar relaxation and attenuation constant have been obtained when changing the direction of the applied magnetic field. Compared with untreated MREs, not only have the minimum reflection loss (RL) and the effective absorption bandwidth (below -20 dB) greatly increased, the frequencies of the absorbing peaks shift about 15%. This suggests that MREs are a magnetic-field-sensitive electromagnetic wave-absorbing material and have great potential in applications such as in anti-radar camouflage, due to the fact that radar can continuously conduct detection at many electromagnetic frequencies, while the MR materials can adjust the microwave-absorption peak according to the radar frequency.

  9. Effects of Perovskite Additives on the Electromagnetic Properties of Z-Type Hexaferrites

    NASA Astrophysics Data System (ADS)

    Lijun Jia,; Yingming Tang,; Huaiwu Zhang,; Pingfeng Deng,; Yingli Liu,; Baoyuan Liu,

    2010-06-01

    In order to modulate the electromagnetic properties of Z-type hexaferrites for high-frequency applications, perovskite additives have been introduced. The effects of these additives on the phase composition, densification, microstructures and electromagnetic properties of the ceramics have been investigated. The results indicate that Ba0.5Sr0.5TiO3 (BST) can promote the grain growth and enhance the sintering by increasing the displacement of ions due to the lattice distortion, which is a result of the solid solubility of Ti4+ in the hexaferrite. The increase of grain size and bulk density and the decrease of magnetocrystalline anisotropy give rise to the improvement of the static permeability. Meanwhile, the dielectric constant increases with BST content due to the changing of the valence of Fe ions in octahedral sites and the polarization of the perovskite phase. In contrast, Pb0.95Sr0.05(Zr0.52Ti0.48)O3 (PZT) is not effective for improving the electromagnetic properties of hexaferrites due to the strong coupling of Ti-O and Zr-O.

  10. Electromagnetic properties of Beryllium-11 in Halo EFT

    NASA Astrophysics Data System (ADS)

    Phillips, Daniel; Hammer, Hans-Werner

    2010-10-01

    We compute properties of ^11Be using an effective field theory (EFT) that exploits the separation of scales in this halo system. This nucleus has both a shallow 1/2^+ and a shallow 1/2^- state. At leading order (LO) in the EFT the theory contains three parameters: the binding energies of these two states, as well as the effective ``range' for p-wave ^10Be-neutron scattering. We use data on the 1/2^+ and 1/2^- levels and the B(E1) strength of the 1/2^+ to 1/2^- transition in the ^11Be nucleus to fix these three parameters. We then compute the dissociation spectrum obtained from Coulomb excitation of the ^11Be nucleus into ^10Be plus a neutron, and compare to experimental data. At LO this spectrum is a prediction of the EFT. At next-to-leading order (NLO) one additional parameter associated with the 1/2^+ state arises. This can be adjusted to obtain a good description of the low-energy part of the dB(E1)/dE spectrum. We also predict the charge radius of the 1/2^+ state, which agrees with experiment at the level expected for an NLO calculation. The convergence pattern of the halo EFT is consistent with the nominal expansion parameter in this system. This allows us to extract the s-wave scattering length and effective range and the p-wave scattering volume in the effective-range expansions that parametrize scattering of a neutron from a ^10Be nucleus.

  11. On the Transport and Radiative Properties of Plasmas with Small-Scale Electromagnetic Fluctuations

    NASA Astrophysics Data System (ADS)

    Keenan, Brett D.

    Plasmas with sub-Larmor-scale ("small-scale") electromagnetic fluctuations are a feature of a wide variety of high-energy-density environments, and are essential to the description of many astrophysical/laboratory plasma phenomena. Radiation from particles, whether they be relativistic or non-relativistic, moving through small-scale electromagnetic turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation. The radiation, carrying information on the statistical properties of the turbulence, is also intimately related to the particle diffusive transport. We investigate, both theoretically and numerically, the transport of non-relativistic and transrelativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence---both with and without a mean field component---and its relation to the spectra of radiation simultaneously produced by these particles. Furthermore, the transport of particles through small-scale electromagnetic turbulence---under certain conditions---resembles the random transport of particles---via Coulomb collisions---in collisional plasmas. The pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasi-collisionality", may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified magneto-optic effects in these plasmas provide an attractive, novel, diagnostic tool for the exploration and characterization of small-scale electromagnetic turbulence. Lastly, we speculate upon the manner in which quasi-collisions may affect inertial confinement fusion (ICF), and other laser-plasma experiments. Finally, we show that mildly relativistic jitter radiation, from laser-produced plasmas, may offer insight into the underlying electromagnetic turbulence. Here we investigate the

  12. A novel preparation of silver-plated polyacrylonitrile fibers functionalized with antibacterial and electromagnetic shielding properties

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Li, Weiya; Gao, Cuicui; Tian, Weicheng; Sun, Bin; Yu, Dan

    2015-07-01

    Polyacrylonitrile (PAN) fibers with antibacterial, electromagnetic shielding and antistatic functionalities were fabricated in this paper through modifying PAN fibers with (3-aminopropyl)triethoxysilane (APTES) and 3-mercaptopropyltriethoxysilane (MPTES) sequentially and followed with silver electroless plating. The silver layer on PAN fiber surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that the silver layer was plated uniformly and compactly. The surface resistance of plated fabric was about 40 mΩ/sq on average. The antibacterial tests demonstrate that silver-plated PAN fiber exhibits excellent antibacterial property against S. aureus and E. coli with a non-leaching characteristic. The antibacterial property remains good after 30 cycles of standard washing, which is a strong proof of a durable adhesion between metal layer and fiber. The shielding effectiveness (SE) of silver-plated PAN fabric before and after 30 cycles of standard washing was about 40-80 dB and 35-50 dB, respectively. This resultant fiber can be used in many occasions for reducing or preventing electromagnetic interference (EMI) and electromagnetic hazards.

  13. Thermophysical properties of substantially undercooled liquid Ti-Al-Nb ternary alloy measured by electromagnetic levitation

    NASA Astrophysics Data System (ADS)

    Zhou, K.; Wang, H. P.; Wei, B.

    2013-03-01

    The thermophysical properties of undercooled liquid alloys at high temperature are usually difficult to measure by experiment. Here, we report the specific heat of liquid Ti45Al45Nb10 ternary alloy in the undercooled state. By using electromagnetic levitation technique, a maximum undercooling of 287 K (0.15 T L) is achieved for this alloy. Its specific heat is determined to be 32.72 ± 2.51 J mol-1 K-1 over a broad temperature range of 1578-2010 K.

  14. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    SciTech Connect

    Khan, Kishwar Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2−2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  15. CoxFey@C Composites with Tunable Atomic Ratios for Excellent Electromagnetic Absorption Properties

    PubMed Central

    Lv, Hualiang; Ji, Guangbin; Zhang, Haiqian; Li, Meng; Zuo, Zhongzheng; Zhao, Yue; Zhang, Baoshan; Tang, Dongming; Du, Youwei

    2015-01-01

    The shell on the nano-magnetic absorber can prevent oxidation, which is very important for its practical utilization. Generally, the nonmagnetic shell will decrease the integral magnetic loss and thus weaken the electromagnetic absorption. However, maintaining the original absorption properties of the magnetic core is a major challenge. Here, we designed novel and facile CoxFey@C composites by reducing CoxFe3−xO4@phenolic resin (x = 1, 0.5 and 0.25). High saturation magnetization value (Ms) of CoxFey particle, as a core, shows the interesting magnetic loss ability. Meanwhile, the carbon shell may increase the integral dielectric loss. The resulting composite shows excellent electromagnetic absorption properties. For example, at a coating thickness of 2 mm, the RLmin value can reach to −23 dB with an effective frequency range of 7 GHz (11–18 GHz). The mechanisms of the improved microwave absorption properties are discussed. PMID:26659124

  16. Aniline doping and high energy milling to greatly enhance electromagnetic properties of magnesium diboride superconductors

    NASA Astrophysics Data System (ADS)

    Wang, Chengduo; Wang, Dongliang; Zhang, Xianping; Yao, Chao; Wang, Chunlei; Ma, Yanwei

    2013-06-01

    MgB2 bulks were fabricated using milled precursor powders with aniline dopant and the low purity B was used as a starting material. The flux pinning, Bc2 and magnetic Jc of MgB2 are greatly enhanced by aniline doping. The magnetic Jc value of MgB2 sample with 3 wt% aniline is 9.5 × 103 A cm-2 at 5 K and 6 T, 13 times larger than that of the pure one. Furthermore, the liquid aniline can avoid the agglomeration of precursor powder during high energy milling. Long time ball milling can further improve the electromagnetic properties of aniline doped MgB2 samples. At 5 K and 6 T, the Jc of the 80 h 3 wt% sample is up to 5.5 × 104 A cm-2, 6 times larger than that of the 0.5 h 3 wt% one and 77 times larger than that of the 0.5 h pure one (the “80 h” and “0.5 h” refer to ball milling times). These results indicate that the liquid C-containing dopant combined with high energy milling may be an effective way to achieve the excellent electromagnetic properties of MgB2.

  17. Heteronanostructured Co@carbon nanotubes-graphene ternary hybrids: synthesis, electromagnetic and excellent microwave absorption properties

    PubMed Central

    Qi, Xiaosi; Hu, Qi; Cai, Hongbo; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

    2016-01-01

    In order to explore high efficiency microwave absorption materials, heteronanostructured Co@carbon nanotubes-graphene (Co@CNTs-G) ternary hybrids were designed and produced through catalytic decomposition of acetylene at the designed temperature (400, 450, 500 and 550 °C) over Co3O4/reduced graphene oxide (Co3O4/RGO). By regulating the reaction temperatures, different CNT contents of Co@CNTs-G ternary hybrids could be synthesized. The investigations indicated that the as-prepared heteronanostructured Co@CNTs-G ternary hybrids exhibited excellent microwave absorption properties, and their electromagnetic and microwave absorption properties could be tuned by the CNT content. The minimum reflection loss (RL) value reached approximately −65.6, −58.1, −41.1 and −47.5 dB for the ternary hybrids synthesized at 400, 450, 500 and 550 °C, respectively. And RL values below −20 dB (99% of electromagnetic wave attenuation) could be obtained over the as-prepared Co@CNTs-G ternary hybrids in the large frequency range. Moreover, based on the obtained results, the possible enhanced microwave absorption mechanisms were discussed in details. Therefore, a simple approach was proposed to explore the high performance microwave absorbing materials as well as to expand the application field of graphene-based materials. PMID:27892515

  18. Heteronanostructured Co@carbon nanotubes-graphene ternary hybrids: synthesis, electromagnetic and excellent microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Qi, Xiaosi; Hu, Qi; Cai, Hongbo; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

    2016-11-01

    In order to explore high efficiency microwave absorption materials, heteronanostructured Co@carbon nanotubes-graphene (Co@CNTs-G) ternary hybrids were designed and produced through catalytic decomposition of acetylene at the designed temperature (400, 450, 500 and 550 °C) over Co3O4/reduced graphene oxide (Co3O4/RGO). By regulating the reaction temperatures, different CNT contents of Co@CNTs-G ternary hybrids could be synthesized. The investigations indicated that the as-prepared heteronanostructured Co@CNTs-G ternary hybrids exhibited excellent microwave absorption properties, and their electromagnetic and microwave absorption properties could be tuned by the CNT content. The minimum reflection loss (RL) value reached approximately ‑65.6, ‑58.1, ‑41.1 and ‑47.5 dB for the ternary hybrids synthesized at 400, 450, 500 and 550 °C, respectively. And RL values below ‑20 dB (99% of electromagnetic wave attenuation) could be obtained over the as-prepared Co@CNTs-G ternary hybrids in the large frequency range. Moreover, based on the obtained results, the possible enhanced microwave absorption mechanisms were discussed in details. Therefore, a simple approach was proposed to explore the high performance microwave absorbing materials as well as to expand the application field of graphene-based materials.

  19. Electromagnetic wave absorption properties of composites with ultrafine hollow magnetic fibers

    NASA Astrophysics Data System (ADS)

    Yi, Jin Woo; Lee, Sang Bok; Kim, Jin Bong; Lee, Sang Kwan; Park, O. Ok

    2014-06-01

    Ultrafine hollow magnetic fibers were prepared by electroless plating using hydrolyzed polyester fiber as a sacrificial substrate. These hollow fibers can be served for lightweight and efficient electromagnetic (EM) absorbing materials. As observed from SEM and EDS analysis, hollow structures consisting of Ni inner layer and Fe or Fe-Co outer layer were obtained. By introducing Co onto Fe, oxidation of the Fe layer was successfully prevented making it possible to enhance the complex permeability compared to a case in which only Fe was used. Polymeric composites containing the hollow fibers with different weight fractions and fiber lengths were prepared by a simple mixing process. The electromagnetic wave properties of the composites were measured by a vector network analyzer and it was found that the hollow magnetic fibers show a clear resonance peak of the complex permittivity around the X-band range (8-12 GHz) and the resonance frequency strongly depends on the fiber concentration and length. A possible explanation for the unique resonance is that the hollow fibers possess relatively low electrical conductivity and a long mean free path due to their oxidized phase and hollow structure. The calculated EM wave absorption with the measured EM wave properties showed that the composite containing 30 wt% hollow Ni/Fe-Co (7:3) fibers in length of 180 μm exhibited multiple absorbance peaks resulting in a broad absorption bandwidth of 4.2 GHz. It is obvious that this multiple absorbance is attributed to the resonance characteristic of the composite.

  20. Design and evaluation of an electromagnetic beam waveguide for measuring electrical properties of materials

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.

    1994-01-01

    A beam waveguide was designed that is based upon the propagation characteristics of the fundamental Gaussian beam and the focusing properties of spherical dielectric lenses. The 20-GHz, two-horn, four-lens system was constructed and experimentally evaluated by probing the field in a plane perpendicular to the beam axis at the center of the beam waveguide system. The critical parameters were determined by numerical sensitivity studies, and the lens-horn critical spacing was adjusted to better focus the beam at the probe plane. The measured performance was analyzed by consideration of higher order Gaussian-Laguerre beam modes. The beam waveguide system was successfully used in the measurements of the electromagnetic transmission properties of Shuttle thermal-protection tiles while the tile surface was being heated to reentry-level temperatures with a high-power laser.

  1. Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates

    USGS Publications Warehouse

    Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

    2008-01-01

    Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on sediments recovered during drilling in the northern Gulf of Mexico at the Atwater Valley and Keathley Canyon sites as part of the 2005 Chevron Joint Industry Project on Methane Hydrates. The tested specimens include both unremolded specimens (as recovered from the original core liner) and remolded sediments both without gas hydrate and with pore fluid exchanged to attain 100% synthetic (tetrahydrofuran) hydrate saturation at any stage of loading. Test results demonstrate the extent to which the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. We also show how permittivity and electrical conductivity data can be used to estimate the evolution of hydrate volume fraction during formation. The gradual evolution of geophysical properties during hydrate formation probably reflects the slow increase in ionic concentration in the pore fluid due to ion exclusion in closed systems and the gradual decrease in average pore size in which the hydrate forms. During hydrate formation, the increase in S-wave velocity is delayed with respect to the decrease in permittivity, consistent with hydrate formation on mineral surfaces and subsequent crystal growth toward the pore space. No significant decementation/debonding occurred in 100% THF hydrate-saturated sediments during unloading, hence the probability of sampling hydrate-bearing sediments without disturbing the original sediment fabric is greatest for samples in which the gas hydrate is primarily responsible for maintaining the sediment fabric and for which the time between core retrieval and restoration of in situ effective stress in the laboratory is minimized. In evaluating the

  2. Thermo-electromagnetic properties of a magnetically shielded superconductor strip: theoretical foundations and numerical simulations

    NASA Astrophysics Data System (ADS)

    Ma, G. T.; Rauh, H.

    2013-10-01

    Numerical simulations of thermo-electromagnetic properties of a thin type-II superconductor strip surrounded by open cavity soft-magnetic shields and exposed to an oscillating transverse magnetic field are performed by resorting to the quasistatic approximation of a vector potential approach in conjunction with the classical description of conduction of heat. The underlying definition of the superconducting constituent makes use of an extended ‘smoothed’ Bean model of the critical state, which includes the field and temperature dependence of the induced supercurrent as well. The delineation of the magnetic shields exploits the reversible-paramagnet approximation in the Langevin form, as appropriate for magnetizations with narrow Z-type loops, and considers induced eddy currents too. The coolant is envisaged as acting like a bath that instantly takes away surplus heat. Based on the Jacobian-free Newton-Krylov approach and the backward Euler scheme, the numerical analysis at hand is tailored to the problem of a high width/thickness aspect ratio of the superconductor strip. Assigning representative materials characteristics and conditions of the applied magnetic field, the main findings for a practically relevant magnet configuration include: (i) an overall rise of the maximum temperature of the superconductor strip tending to saturation in a superconducting thermo-electromagnetic steady state above the operating temperature, magnetic shielding lending increased stability and smoothing the temperature profile along the width of the superconductor strip; (ii) a washing out of the profile of the magnetic induction and a lowering of its strength, a relaxation of the profile of the supercurrent density and an increase of its strength, a tightening of the power loss density and a reduction of its strength, all inside the superconductor strip. The hysteretic ac loss suffered by the superconductor strip is seen to be cut back or, at most, to converge on that of an

  3. Electromagnetic performance and microwave absorbing property of nanocrystalline Sm2Fe14B compound

    NASA Astrophysics Data System (ADS)

    Han, Rui; Yi, Hai-bo; Wei, Jian-qiang; Qiao, Liang; Wang, Tao; Li, Fa-shen

    2012-09-01

    A new planar anisotropy Sm2Fe14B nanocrystal as an electromagnetic absorption material was prepared by melt-spinning method. The electromagnetic and microwave absorbing properties of Sm2Fe14B nanocrystal/nonmagnetic matrix composite in the frequency range of 0.1-10 GHz were measured and calculated. At the perfect matching point (2.9 GHz), the minimum reflection loss reaches -42.0 dB at the matching thickness of 3.1 mm. Furthermore, the calculation shows that the normalized input impedance Z in/ Z 0 equals 1, but the modulus of the ratio between the complex permittivity and permeability | ɛ/ μ| is far away from unity at the perfect matching point. The effective permeability of the composite was simulated using the combination of the Landau-Lifshitz-Gilbert equation and Bruggeman's effective medium theory; the agreement between the experimental data and the theoretical one demonstrates that the magnetic loss in the composite is mainly caused by natural resonance.

  4. Electrical Properties and Electromagnetic Shielding Effectiveness of Carbon Based Epoxy Nanocomposites

    NASA Astrophysics Data System (ADS)

    Bellucci, S.; Micciulla, F.; Sacco, I.; Coderoni, L.; Rinaldi, G.

    Designing and engineering of new kind of electromagnetic interference (EMI) shielding for electronic systems and devices is a pressing need due to the wide range of using of several electronic devices. Electromagnetic (EM) shields have to guarantee high performances and right operation of electronic systems and to prevent the electronic pollution. Electronic systems are getting faster, smaller high frequency of clock and high energy in small dimension, so they generate, as effect, thermal drawback, and mechanical, as well. They are used in several electronic equipments and it is easy to find them in common life: communications, computations, automations, biomedical, military, space and other purposes. Nanocomposites based on Carbon Nanotubes (CNTs) give powerful and multifunctional materials with very high performances: mechanical, thermal, electrical properties. It is possible to achieve lighter and cheaper EM shields than the actual ones. Examples of new materials that can come from nanotubes are many: high conductors that are multifunctional (electrical and structural), highly anisotropic insulators and high-strength, porous ceramics and others.

  5. Core mass at the helium flash from observations and a new bound on neutrino electromagnetic properties

    NASA Technical Reports Server (NTRS)

    Raffelt, Georg G.

    1990-01-01

    Existing measurements of the bolometric magnitudes of the brightest red giants in 26 globular clusters are used to determine the brightness difference between the tip of the red giant branch (on average found to be 0.1 mag brighter than the brightest red giant) and RR Lyrae stars. The metallicity variation of the result agrees perfectly with theoretical predictions. In conjunction with previous determinations of the number ratio of horizontal-branch versus red giant stars, with statistical parallax determinations of RR Lyrae absolute luminosities, and with theoretical predictions based on the Sweigart and Gross evolutionary sequences, this result yields an allowed range for a hypothetical core mass variation relative to the standard results of (0.009 + or - 0.012) solar mass. If neutrinos had anomalous electromagnetic dipole moments, the increased energy loss near the helium flash would lead to an increased core mass. Constraints on neutrino electromagnetic properties are determined from the color-magnitude diagrams of the globular clusters.

  6. Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

    USGS Publications Warehouse

    Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

    2010-01-01

    The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

  7. Electromagnetic properties of Co flaky particles prepared via ball-milling method

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Jiang, Jian-Tang; Yuan, Yong; Gong, Yuan-Xun; Zhen, Liang

    2016-10-01

    Flaky cobalt particles with different aspect ratio were produced with ball-milling method. The phase structure and morphology of the particles were identified by XRD analysis and SEM observation. The static magnetic and electromagnetic properties of the particles were measured and effects of shape, microstructure and filling fraction were investigated. Phase transition from fcc lattice to hcp lattice occur due to the drive of ball-milling is responsible for the largely increased coercivity. Particles with high aspect ratio are found to possess high permittivity and permeability, compelling the frequency of absorption peak to shift to low frequency. Coatings using cobalt particles milled for 20 h as fillers present a RL peak of -33 dB at 8 GHz at the thickness of 2.5 mm together with a broad effective absorbing (RL below -10 dB) bandwidth covering 6-10 GHz.

  8. Improved Electromagnetic Interference Shielding Properties of MWCNT–PMMA Composites Using Layered Structures

    PubMed Central

    2009-01-01

    Electromagnetic interference (EMI) shielding effectiveness (SE) of multi-walled carbon nanotubes–polymethyl methacrylate (MWCNT–PMMA) composites prepared by two different techniques was measured. EMI SE up to 40 dB in the frequency range 8.2–12.4 GHz (X-band) was achieved by stacking seven layers of 0.3-mm thick MWCNT–PMMA composite films compared with 30 dB achieved by stacking two layers of 1.1-mm thick MWCNT–PMMA bulk composite. The characteristic EMI SE graphs of the composites and the mechanism of shielding have been discussed. SE in this frequency range is found to be dominated by absorption. The mechanical properties (tensile, flexural strength and modulus) of the composites were found to be comparable or better than the pure polymer. The studies therefore show that the composite can be used as structurally strong EMI shielding material. PMID:20596500

  9. Pr 3+-substituted W-type barium ferrite: Preparation and electromagnetic properties

    NASA Astrophysics Data System (ADS)

    Wu, Yanfei; Huang, Ying; Niu, Lei; Zhang, Yinling; Li, Yuqing; Wang, Xiaoya

    2012-02-01

    The W-type ferrites doped with Pr3+, BaCoNiPrxFe16-xO27 (x=0-0.20), were prepared by a sol-gel method. The structure and electromagnetic properties of the samples are studied using powder X-ray diffraction, field emission scanning electron microscope, vibrating sample magnetometer and vector network analyzer. All the samples are hexagonal platelet-like W-type barium ferrite. These synthesized samples exhibit paramagnetism and strong magnetism. The saturation magnetization (Ms) increases with the increase of Pr3+ content. The real part of complex permittivity (ε‧) decreases and the imaginary part (ε″) increases with Fe3+ replaced by Pr3+. The imaginary part of complex permittivity (μ″) increases and the real part (μ‧) decreases after Pr3+ is doped. Furthermore, the doped Pr3+ improves the microwave absorbency.

  10. THE GENERATION OF THERMOELASTIC STRESS WAVES BY IMPULSIVE ELECTROMAGNETIC RADIATION.

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , ABSORPTION), (*STRESSES, ELECTROMAGNETIC RADIATION ), SURFACE PROPERTIES, INTERACTIONS, HEAT TRANSFER, ELASTIC PROPERTIES, ELECTROMAGNETIC PULSES, LASERS, MATHEMATICAL ANALYSIS, BOUNDARY VALUE PROBLEMS, SOLIDS

  11. Dielectric properties of tissues; variation with age and their relevance in exposure of children to electromagnetic fields; state of knowledge.

    PubMed

    Peyman, Azadeh

    2011-12-01

    This paper reviews and summarises the state of knowledge on dielectric properties of tissues; in particular those obtained as a function of age. It also examines the impact of variation in dielectric data on the outcome of recent dosimetric studies assessing the exposure of children to electromagnetic fields.

  12. Influence of Acoustic and Electromagnetic Actions on the Properties of Aqueous Nanoparticle Dispersions Used as Tempering Liquids for Dental Cement

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Goncharik, S. V.; Chubrik, N. N.; Koshevar, V. D.; Lopat‧ko, K. G.; Aftandilyants, E. G.; Veklich, A. N.; Boretskii, V. F.; Orlovich, A. I.

    2016-05-01

    The authors have studied the physicochemical properties of aqueous dispersions containing carbon, silver, and iron nanoparticles which were produced by elastic-spark synthesis under the conditions of subaqueous spark discharge, and also the influence of preliminary acoustic and high-frequency electromagnetic action on them and the change in the functional indices of the glass-ionomer cement tempered by these dispersions.

  13. Synthesis, multi-nonlinear dielectric resonance and electromagnetic absorption properties of hcp-cobalt particles

    NASA Astrophysics Data System (ADS)

    Wen, Shulai; Liu, Ying; Zhao, Xiuchen; Cheng, Jingwei; Li, Hong

    2014-03-01

    Hcp-cobalt particles were successfully prepared by a liquid phase reduction method, and the microstructure, static magnetic properties, electromagnetic and microwave absorption properties of the cobalt particles with irregular shape were investigated in detail. The measured results indicate that the saturation magnetization was less than that of hcp-Co single crystals, and the coercivity was larger than that of bulk cobalt crystal. The permittivity presents multi-nonlinear dielectric resonance, which may result from the irregular shape containing parts of cutting angle of dodecahedron of cobalt particles. The real part of permeability decreases with the frequency, and the imaginary part has a wide resonant peak. The paraffin-based composite containing 70 wt% cobalt particles possessed strong absorption characteristics with a minimum RL of -38.97 dB at 10.81 GHz and an absorption band with RL under -10 dB from 8.72 to 13.26 GHz when the thickness is 1.8 mm, which exhibits excellent microwave absorption in middle and high frequency. The architectural design of material morphologies is important for improving microwave absorption properties toward future application.

  14. The effect of filler aspect ratio on the electromagnetic properties of carbon-nanofibers reinforced composites

    NASA Astrophysics Data System (ADS)

    De Vivo, B.; Lamberti, P.; Spinelli, G.; Tucci, V.; Guadagno, L.; Raimondo, M.

    2015-08-01

    The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500 °C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107 S/m and 1.36 × 10-3 S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1 wt. % of nanofiller loading, while the electrical percolation threshold falls in the range [0.05-0.32]wt. % for the first nanocomposites and above 0.64 wt. % for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.

  15. Effect of aluminum substitution on structural and electromagnetic properties of nanocrystalline MgCuMn ferrites

    SciTech Connect

    Ramesh, T. E-mail: ramanasarabu@gmail.com; Kumar, S. Senthil; Shinde, R. S.; Murthy, S. R.

    2015-06-24

    The effect of substitution of nonmagnetic Al{sup 3+} ions on the structural and electromagnetic properties were studied in nanocrystalline ferrite series of Mg{sub 0.8}Cu{sub 0.2}Al{sub x}Fe{sub 1.95-x}Mn{sub 0.05}O{sub 4} where x varies 0-0.4 in steps of 0.1. This series was synthesized by using microwave hydrothermal method. The nanocrystalline ferrite phase was observed at temperature 150°C/40 min. Synthesized powders were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The synthesized powders were densified using microwave sintering method at 950°C/40 min. The sintered samples were characterized using XRD. Surface morphology was observed by using field effective scanning electron microscopy (FESEM). The electrical and magnetic properties were measured at room temperature. These results led us to interfere that the values of d.c resistivity increases and dielectric constant, initial permeability, saturation magnetization and Curie temperature were observed to be decreased with the substitution of Al{sup 3+} ions with those of Fe{sup 3+}. The low dielectric and magnetic losses and low magnetization exhibited by aluminum substituted MgCuMn ferrites makes them find applications in microwave devices.

  16. The properties of electromagnetic responses and optical modulation in terahertz metamaterials

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Shi, Yulei; Wang, Wei; Zhou, Qingli; Zhang, Cunlin

    2016-11-01

    Metamaterials with subwavelength structural features show unique electromagnetic responses that are unattainable with natural materials. Recently, the research on these artificial materials has been pushed forward to the terahertz (THz) region because of potential applications in biological fingerprinting, security imaging, and high frequency magnetic and electric resonant devices. Furthermore, active control of their properties could further facilitate and open up new applications in terms of modulation and switching. In our work, we will first present our studies of dipole arrays at terahertz frequencies. Then in experimental and theoretical studies of terahertz subwavelength L-shaped structure, we proposed an unusual-mode current resonance responsible for low-frequency characteristic dip in transmission spectra. Comparing spectral properties of our designed simplified structures with that of split-ring resonators, we attribute this unusual mode to the resonance coupling and splitting under the broken symmetry of the structure. Finally, we use optical pump-terahertz probe method to investigate the spectral and dynamic behaviour of optical modulation in the split-ring resonators. We have observed the blue-shift and band broadening in the spectral changes of transmission under optical excitation at different delay times. The calculated surface currents using finite difference time domain simulation are presented to characterize these resonances, and the blue-shift can be explained by the changed refractive index and conductivity in the photoexcited semiconductor substrate.

  17. Electromagnetic properties of NiZn ferrite nanoparticles and their polymer composites

    SciTech Connect

    Parsons, P.; Duncan, K.; Giri, A. K.; Xiao, J. Q.; Karna, S. P.

    2014-05-07

    The magnetic properties of polycrystalline NiZn ferrite nanoparticles synthesized using a polyol-reduction and coprecipitation reaction methods have been investigated. The effects on magnetization of synthesis approach, chemical composition, processing conditions, and on the size of nanoparticles on magnetization have been investigated. The measured room-temperature magnetization for the as-prepared magnetic nanoparticles (MNP) synthesized via polyol-reduction and coprecipitation is 69 Am{sup 2} kg{sup −1} and 14 Am{sup 2} kg{sup −1}, respectively. X-ray diffraction measurements confirm spinel structure of the particles with an estimated grain size of ∼80 nm obtained from the polyol-reduction and 28 nm obtained from these coprecipitation techniques. Upon calcination under atmospheric conditions at different temperatures between 800 °C and 1000 °C, the magnetization, M, of the coprecipitated MNP increases to 76 Am{sup 2} kg{sup −1} with an estimated grain size of 90 nm. The MNP-polymer nanocomposites made from the synthesized MNP in various loading fraction and high density polyethylene exhibit interesting electromagnetic properties. The measured permeability and permittivity of the magnetic nanoparticle-polymer nanocomposites increases with the loading fractions of the magnetic nanoparticles, suggesting control for impedance matching for antenna applications.

  18. Electro-magnetic properties of composites with aligned Fe-Co hollow fibers

    NASA Astrophysics Data System (ADS)

    Cho, Seungchan; Choi, Jae Ryung; Jung, Byung Mun; Choi, U. Hyeok; Lee, Sang-Kwan; Kim, Ki Hyeon; Lee, Sang-Bok

    2016-05-01

    A novel Fe-Co binary hollow fiber was synthesized by electroless plating using hydrolyzed polyester fiber and its anisotropy characteristic was investigated for electromagnetic wave absorbing materials. The hollow fibers in parallel with magnetic field show higher saturated magnetization of 202 emu/g at the applied magnetic field of 10 kOe and lower coercivity (27.658 Oe), compared with the random and vertical oriented hollow fibers. From complex permittivity measurement, the Fe-Co hollow fiber composites clearly display a single dielectric resonance, located at ˜14 GHz. The Fe-Co hollow fibers not only provide excellent EM properties in GHz frequency ranges, resulting mainly from the strong resonance, but also adjust the soft magnetic properties through fiber alignments. The cavitary structure of the Fe-Co hollow fibers, not only giving rise to a dielectric loss resonance and also adjusting its peak frequency, may be a pathway to useful EM wave absorptive devices in GHz frequency ranges.

  19. Electromagnetic properties and microwave absorption properties of BaTiO 3-carbonyl iron composite in S and C bands

    NASA Astrophysics Data System (ADS)

    Rui-gang, Yang

    2011-07-01

    BaTiO3 powders are prepared by sol-gel method. The carbonyl iron powder is prepared via thermal decomposition of iron pentacarbonyl. Then BaTiO3-carbonyl iron composite with different mixture ratios was prepared using the as-prepared material. The structure, morphology, and properties of the composites are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy (SEM), and a network analyzer. The complex permittivity and reflection loss of the composites have been measured at different microwave frequencies in S- and C-bands employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3/carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-carbonyl iron composite has been proposed. The BaTiO3-carbonyl iron composite can find applications in suppression of electromagnetic interference, and reduction of radar signature.

  20. The effect of filler aspect ratio on the electromagnetic properties of carbon-nanofibers reinforced composites

    SciTech Connect

    De Vivo, B.; Lamberti, P.; Spinelli, G. Tucci, V.; Guadagno, L.; Raimondo, M.

    2015-08-14

    The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500 °C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107 S/m and 1.36 × 10{sup −3} S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1 wt. % of nanofiller loading, while the electrical percolation threshold falls in the range [0.05–0.32]wt. % for the first nanocomposites and above 0.64 wt. % for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.

  1. Electromagnetic and Microwave-Absorbing Properties of Plate-Like Nd-Ce-Fe Powder

    NASA Astrophysics Data System (ADS)

    Qiao, Ziqiang; Pan, Shunkang; Xiong, Jilei; Cheng, Lichun; Lin, Peihao; Luo, Jialiang

    2017-01-01

    Plate-like Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders have been synthesized by an arc melting and high-energy ball milling method. The structure of the Nd-Ce-Fe powders was investigated by x-ray diffraction analysis. Their morphology and particle size distribution were evaluated by scanning electron microscopy and laser particle analysis. The saturation magnetization and electromagnetic parameters of the powders were characterized using vibrating-sample magnetometry and vector network analysis, respectively. The results reveal that the Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders consisted of Nd2Fe17 single phase with different Ce contents. The particle size and saturation magnetization decreased with increasing Ce content. The resonant frequencies of ɛ″ and μ″ moved towards lower frequency with increasing Ce concentration. The minimum reflection loss value decreased as the Ce content was increased. The minimum reflection loss and absorption peak frequency of Ce0.2Nd1.8Fe17 with coating thickness of 1.8 mm were -22.5 dB and 7 GHz, respectively. Increasing the values of the complex permittivity and permeability could result in materials with good microwave absorption properties.

  2. Radio to microwave dielectric characterisation of constitutive electromagnetic soil properties using vector network analyses

    NASA Astrophysics Data System (ADS)

    Schwing, M.; Wagner, N.; Karlovsek, J.; Chen, Z.; Williams, D. J.; Scheuermann, A.

    2016-04-01

    The knowledge of constitutive broadband electromagnetic (EM) properties of porous media such as soils and rocks is essential in the theoretical and numerical modeling of EM wave propagation in the subsurface. This paper presents an experimental and numerical study on the performance EM measuring instruments for broadband EM wave in the radio-microwave frequency range. 3-D numerical calculations of a specific sensor were carried out using the Ansys HFSS (high frequency structural simulator) to further evaluate the probe performance. In addition, six different sensors of varying design, application purpose, and operational frequency range, were tested on different calibration liquids and a sample of fine-grained soil over a frequency range of 1 MHz-40 GHz using four vector network analysers. The resulting dielectric spectrum of the soil was analysed and interpreted using a 3-term Cole-Cole model under consideration of a direct current conductivity contribution. Comparison of sensor performances on calibration materials and fine-grained soils showed consistency in the measured dielectric spectra at a frequency range from 100 MHz-2 GHz. By combining open-ended coaxial line and coaxial transmission line measurements, the observable frequency window could be extended to a truly broad frequency range of 1 MHz-40 GHz.

  3. Effect of cooling rate on structural and electromagnetic properties of high-carbon ferrochrome powders

    NASA Astrophysics Data System (ADS)

    Yang, Jian-ping; Chen, Jin; Hao, Jiu-jiu; Guo, Li-na; Liu, Jin-ying

    2016-03-01

    The structural and electromagnetic properties of high-carbon ferrochrome powders (HCFCP) obtained at different cooling rates were respectively investigated by means of optical microscope, X-ray diffractometer, electron probe as well as the vector network analyzer in the frequency range of 1-18 GHz. The results show that the cell structure of main phase, (Cr,Fe)7C3, transforms from hexagonal to orthogonal with the improvement of cooling rate. Meanwhile the mass ratio of Cr to Fe in (Cr,Fe)7C3 gradually declines, while that for CrFe goes up. Both the real part and the imaginary part of relative complex permittivity of HCFCP are in an increasing order with cooling rate rising in most frequencies. For comparison, the relative complex permeability presents an opposite changing tendency. The peaks of the imaginary part of relative complex permeability appearing in low and high frequencies are attributed to nature resonance. The reflection loss of HCFCP gradually decreases as cooling rate reduces and frequency enhances. At 2.45 GHz, the algebraic sum of dielectric loss factor and magnetic loss factor increases first and then decreases in the temperature extent from 298 K to 1273 K.

  4. The unexplored avenues of human skin: electromagnetic properties in the sub-THz band

    NASA Astrophysics Data System (ADS)

    Feldman, Y.; Safrai, E.; Ben Ishai, P.; Puzenko, A.; Agranat, A. J.; Caduff, A.

    2012-03-01

    Recent studies of the minute morphology of the skin by optical coherence tomography showed that the sweat ducts in human skin become helically shaped tubes in the Epidermis and are filled with an aqueous solution. When considered as entities embedded in a dielectric media, they resemble helical antennas. The spectral response obtained by our computer simulations coincides with the analytical prediction of antenna theory and support this hypothesis, if a fast enough current mechanism exists in the duct. In particular the strongest spectral response of the simulation was noted around the predicted frequencies (240 GHz and 380 GHz) for the respective normal and axial modes of the helical structure. Furthermore, circular dichroism of the reflected electromagnetic field is a characteristic property of such helical antennas and it was shown that it is indeed a characteristic of the simulation model. Fast proton hopping is posited as the current mechanism. Consequently experimental evidence is presented that the spectral response of the skin in the sub-Terahertz region is governed by the level of activity of the perspiration system. This in turn is moderated by the Sympathetic Nerve Response and is demonstrated by the correlation to physiological stress as manifested by the pulse rate and the systolic blood pressure. These physical relaxations are tonic in nature (lasting more than a minute). Could the phasic characteristic of emotional excitation also be evident in the reflection coefficient? By applying techniques borrowed from psychiatric science we hope to answer this point in our paper.

  5. Controlled synthesis and morphology-dependent electromagnetic properties of nickel nanostructures by γ-ray irradiation technique

    NASA Astrophysics Data System (ADS)

    Hongtao, Zhao; Xijiang, Han; Lifang, Zhang; Gangyi, Wang; Chao, Wang; Xueai, Li; Ping, Xu

    2011-03-01

    We report the morphology-dependent magnetic and electromagnetic absorption properties of various nickel nanostructures prepared by a γ-ray irradiation technique. By changing the applied surfactants during the irradiation, sting-like, agglomerated, and chain-like nickel nanostructures are obtained when using polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and sodium dodecyl benzene sulfonate (SDBS) as the surfactants. It is determined that the excellent electromagnetic absorption ability of sting-like nickel arises from point discharge effect, while chain-like nickel shows the best absorption property due to the geometrical effect. We think that the preparation of nickel nanostructures with various morphologies by this facile γ-ray irradiation technique can be a general route for other metals.

  6. Dynamic Properties of Round Window Membrane in Guinea Pig Otitis Media Model Measured with Electromagnetic Stimulation

    PubMed Central

    Gan, Rong Z.; Nakmali, Don; Zhang, Xiangming

    2013-01-01

    The round window, one of two openings into the cochlea from the middle ear, plays an important role in hearing and is known to be structurally altered during otitis media. However, there have been no published studies systematically describing the changes in biomechanical properties of the round window membrane (RWM) that accompany bacterial otitis media. Here we describe the occurrence of significant changes in the dynamic properties of the RWM between normal guinea pigs and those with acute otitis media (AOM) that are detectable by electromagnetic force stimulation and laser Doppler vibrometry (LDV) measurements. AOM was induced by transbullar injection of streptococcus pneumoniae into the middle ear, and RWM specimens were prepared three days after challenge. Vibration of the RWM induced by coil-magnet coupling was measured by LDV over frequencies of 0.2–40 kHz. The experiment was then simulated in a finite element model, and the inverse-problem solving method was used to determine the complex modulus in the frequency domain and the relaxation modulus in the time domain. Results from 18 ears (9 control ears and 9 AOM ears) established that both the storage modulus and loss modulus of the RWM from ears with AOM were significantly lower than those of RWM from uninfected ears. The average decrease of the storage modulus in AOM ears ranged from 1.5 to 2.2 MPa and the average decrease of the loss modulus was 0.025 to 0.48 MPa. Our findings suggest that middle ear infection primarily affects the stiffness of the RWM due to the morphological changes that occur in AOM ears. We also conclude that the coil-magnet coupling method for assessment of RWM function may provide a valuable new approach to characterizing the mechanical response of the RWM when reverse driving is selected for middle ear implantable devices. PMID:23333258

  7. Properties of electrons scattered by a strong plane electromagnetic wave with a linear polarization: Semiclassical treatment

    NASA Astrophysics Data System (ADS)

    Bogdanov, O. V.; Kazinski, P. O.

    2015-02-01

    The problem of scattering of ultrarelativistic electrons by a strong plane electromagnetic wave of a low (optical) frequency and linear polarization is solved in the semiclassical approximation, when the electron wave packet size is much smaller than the wavelength of electromagnetic wave. The exit momenta of ultrarelativistic electrons scattered are found using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of electrons traversed the electromagnetic wave depend weakly on the initial values of momenta. These electrons are mostly scattered at small angles to the propagation direction of the electromagnetic wave. The maximum Lorentz factor of electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momentum. The momentum component parallel to the electric field vector of the electromagnetic wave is determined solely by the laser beam diameter measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. A reflection law that relates the incident and reflection angles and is independent of any parameters is found.

  8. Porous Three-Dimensional Flower-like Co/CoO and Its Excellent Electromagnetic Absorption Properties.

    PubMed

    Lv, Hualiang; Liang, Xiaohui; Ji, Guangbin; Zhang, Haiqian; Du, Youwei

    2015-05-13

    The porous three-dimensional (3-D) flower structures assembled by numerous ultrathin flakes were favor for strengthen electromagnetic absorption capability. However, it still remains a big challenge to fabricate such kind of materials. In this study, an easy and flexible two-step method consisting of hydrothermal and subsequent annealing process have been developed to synthesize the porous 3-D flower-like Co/CoO. Interestingly, we found that the suitable heat treatment temperature played a vital role on the flower-like structure, composition, and electromagnetic absorption properties. In detail, only in the composite treated with 400 °C can we gain the porous 3-D flower structure. If the annealing temperature were heated to 300 °C, the Co element was unable to generate. Moreover, when the annealing temperature increased from 400 to 500 °C, these flower-like structures were unable to be kept because the enlarged porous diameter would wreck the flower frame. Moreover, these 3-D porous flower-like structures presented outstanding electromagnetic absorption properties. For example, such special structure enabled an optimal reflection loss value of -50 dB with the frequency bandwidth ranged from 13.8 to 18 GHz. The excellent microwave absorption performance may attribute to the high impedance matching behavior and novel dielectric loss ability. Additionally, it can be supposed that this micrometer-size flower structure was more beneficial to scatter the incident electromagnetic wave. Meanwhile, the rough surface of the ultrathin flake is apt to increase the electromagnetic scattering among the leaves of the flower due to their large spacing and porous features.

  9. Influence of electromagnetic radiation produced by mobile phone on some biophysical blood properties in rats.

    PubMed

    El-Bediwi, Abu Bakr; Saad, Mohamed; El-kott, Attall F; Eid, Eman

    2013-04-01

    Effects of electromagnetic radiation produced by mobile phone on blood viscosity, plasma viscosity, hemolysis, Osmotic fragility, and blood components of rats have been investigated. Experimental results show that there are significant change on blood components and its viscosity which affects on a blood circulation due to many body problems. Red blood cells, White blood cells, and Platelets are broken after exposure to electromagnetic radiation produced by mobile phone. Also blood viscosity and plasma viscosity values are increased but Osmotic fragility value decreased after exposure to electromagnetic radiation produced by mobile phone.

  10. Measuring electromagnetic properties of superconductors in high and localized rf magnetic field

    NASA Astrophysics Data System (ADS)

    Tai, Tamin

    possible nonlinear mechanism from switching events between the Meissner state and the mixed state. These models of extrinsic nonlinearity are studied in Chapter 6. The high transition temperature and low surface resistance of MgB2 attracts interest in its potential application in superconducting radio frequency accelerating cavities. However, compared to traditional Nb cavities, the viability of MgB2 at high RF fields is still open to question. Hence, in Chapter 7, two-gap high quality MgB2 films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor deposition technique on dielectric substrates, are measured at a fixed location to investigate its RF properties. The third harmonic measurement on MgB2 films shows different nonlinear mechanisms compared to the bulk Nb measurement [3] . We conclude that the nonlinear response for the high quality MgB2 films at temperature less than Tc shows the nonlinearity from the moving vortices and from the following possible mechanisms: First, an intrinsic nonlinearity from the proximity-induced second Tc. Second, the intrinsic nonlinearity arising from Josephson coupling between the sigma and pi bands of the two gap nature of MgB2. Third: The potential nonlinearity from the reported superconducting nodal gap properties. Finally the future plan to raster scan on the SRF candidate materials is proposed to relate the nonlinear electromagnetic images to the physical defects on the superconductor surface. These efforts can finally feed back to the cavity processing techniques and suggest new thoughts for alternate surface processing treatment in the future. [1] T. Tai, et al., IEEE Trans. Appl. Supercond. 21, 2615, (2011). [2] T. Tai et al., IEEE Trans. Appl. Supercond. 23, 7100104, (2013). [3] T. Tai et al., Phys. Rev. ST Accel. Beams 15, 122002, (2012).

  11. Electromagnetic energy within a magnetic infinite cylinder and scattering properties for oblique incidence.

    PubMed

    Arruda, Tiago José; Martinez, Alexandre Souto

    2010-07-01

    We analytically calculate the time-averaged electromagnetic energy stored inside a nondispersive magnetic isotropic cylinder that is obliquely irradiated by an electromagnetic plane wave. An expression for the optical-absorption efficiency in terms of the magnetic internal coefficients is also obtained. In the low absorption limit, we derive a relation between the normalized internal energy and the optical-absorption efficiency that is not affected by the magnetism and the incidence angle. This relation, indeed, seems to be independent of the shape of the scatterer. This universal aspect of the internal energy is connected to the transport velocity and consequently to the diffusion coefficient in the multiple scattering regime. Magnetism favors high internal energy for low size parameter cylinders, which leads to a low diffusion coefficient for electromagnetic propagation in 2D random media.

  12. Epoxy composites filled with high surface area-carbon fillers: Optimization of electromagnetic shielding, electrical, mechanical, and thermal properties

    NASA Astrophysics Data System (ADS)

    Kuzhir, P.; Paddubskaya, A.; Plyushch, A.; Volynets, N.; Maksimenko, S.; Macutkevic, J.; Kranauskaite, I.; Banys, J.; Ivanov, E.; Kotsilkova, R.; Celzard, A.; Fierro, V.; Zicans, J.; Ivanova, T.; Merijs Meri, R.; Bochkov, I.; Cataldo, A.; Micciulla, F.; Bellucci, S.; Lambin, Ph.

    2013-10-01

    A comprehensive analysis of electrical, electromagnetic (EM), mechanical, and thermal properties of epoxy resin composites filled with 0.25-2.0 wt. % of carbon additives characterized by high surface area, both nano-sized, like carbon nanotubes (CNTs) and carbon black (CBH), and micro-sized exfoliated graphite (EG), was performed. We found that the physical properties of both CNTs- and CBH-based epoxy resin composites increased all together with filler content and even more clearly for CBH than for CNTs. In the case of EG-based composites, good correlation between properties and filler amount was observed for concentrations below 1.5 wt. %. We conclude that CBH and, to a lower extent, EG could replace expensive CNTs for producing effective EM materials in microwave and low-frequency ranges, which are, in addition, mechanically and thermally stable.

  13. The Electromagnetic and Mechanical Properties of Structural Composites: A Theoretical and Experimental Design Study

    DTIC Science & Technology

    2014-08-22

    rigorous electromagnetic methods can be used for this purpose, including the finite element method (FEM), finite difference time domain (FDTD) and modal...architectures and to multilayered laminates. In this project, experimental validation from 4-50 GHz is provided for single layers of dry structural grade...originally presented by Moharam and Gaylord. 10 zi E" X \\ ’ As. p reflected \\ i / Figure 7. Solution domain used by the rigorous

  14. Coherence and Polarization Properties of Far Fields Generated by Quasi-Homogeneous Planar Electromagnetic Sources (Postprint)

    DTIC Science & Technology

    2005-02-03

    the explicit dependence of all he parameters on the frequency. In order that the elec- romagnetic Gaussian Schell - model source generated by eans of the...the far field gener- ted by a planar electromagnetic Gaussian Schell - model ource are given by the expressions s1 rs, = xx 2 exp− xx 2 k2 2/2...uniformly polarized, quasi- omogeneous Gaussian Schell - model source, which is haracterized by a cross-spectral density matrix J rs ,rs , whose

  15. Changes in the statistical properties of stochastic anisotropic electromagnetic beams on propagation in the turbulent atmosphere.

    PubMed

    Du, Xinyue; Zhao, Daomu; Korotkova, Olga

    2007-12-10

    We report analytic formulas for the elements of the e 2 X2 cross-spectral density matrix of a stochastic electromagnetic anisotropic beam propagating through the turbulent atmosphere with the help of vector integration. From these formulas the changes in the spectral density (spectrum), in the spectral degree of polarization, and in the spectral degree of coherence of such a beam on propagation are determined. As an example, these quantities are calculated for a so-called anisotropic electromagnetic Gaussian Schell-model beam propagating in the isotropic and homogeneous atmosphere. In particular, it is shown numerically that for a beam of this class, unlike for an isotropic electromagnetic Gaussian Schell-model beam, its spectral degree of polarization does not return to its value in the source plane after propagating at sufficiently large distances in the atmosphere. It is also shown that the spectral degree of coherence of such a beam tends to zero with increasing distance of propagation through the turbulent atmosphere, in agreement with results previously reported for isotropic beams.

  16. Effect of pH value on electromagnetic loss properties of Co-Zn ferrite prepared via coprecipitation method

    NASA Astrophysics Data System (ADS)

    Huang, Xiaogu; Zhang, Jing; Wang, Wei; Sang, Tianyi; Song, Bo; Zhu, Hongli; Rao, Weifeng; Wong, Chingping

    2016-05-01

    In this paper, the cobalt zinc ferrite was prepared by coprecipitation method at different pH conditions. The influence of pH values on the coprecipitation reaction was theoretically analyzed at first. The calculated results showed that the pH values should be controlled in the range of 9-11 to form the stable precipitation. The XRD investigation was used to further confirm the formation of the composite on specific pH values. In addition, the morphological study revealed that the average particle size of the composite decreased from 40 nm to 30 nm when the pH value increased from 9-11. The variation of microstructure plays a critical role in controlling the electromagnetic properties. From the electromagnetic analysis, the dielectric loss factor was 0.02-0.07 and magnetic loss factor was 0.2-0.5 for the composite synthesized at pH of 9, which presents dramatically improved dielectric loss and magnetic loss properties than the samples prepared at pH of 10 and 11. The as-prepared cobalt zinc ferrite are highly promising to be used as microwave absorption materials.

  17. Electromagnetic and microwave absorbing properties of carbonyl iron/BaTiO3 composite absorber for matched load of isolator

    NASA Astrophysics Data System (ADS)

    Ren, Xiaohu; Cheng, Yankui

    2015-11-01

    Composite absorbers made from carbonyl iron powder and BaTiO3 were prepared by blending technique with the matrix of epoxy resin. The structure and microtopography of the carbonyl iron and BaTiO3 particles were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructure and electromagnetic properties of the as-prepared composites were investigated by SEM and vector network analyzer (VNA). The effect of the mass ratio of BaTiO3/carbonyl iron on the electromagnetic properties of the composites is investigated. The bandwidth with an absorption loss exceeding 30 dB is obtained in the whole measured frequency range for all composites, and an optimal reflection loss drop below 1.5 dB with 24 wt% BaTiO3. It is found that the carbonyl iron/BaTiO3 composite absorber can be a promising candidate as a matched load for the isolator.

  18. Influence of direct bias current on the electromagnetic properties of melt-extracted microwires and their composites

    NASA Astrophysics Data System (ADS)

    Qin, F. X.; Tang, J.; Popov, V. V.; Liu, J. S.; Peng, H. X.; Brosseau, C.

    2014-01-01

    We study the influence of a direct bias current on the magnetoimpedance (MI) in melt-extracted amorphous CoFeSiB microwires and the effective electromagnetic properties of epoxy composites filled with these microwires. Our analysis reveals two remarkable features of the current dependence of MI in the range of gigahertz frequencies: a redshift of the dielectric resonance frequency and a decrease of the peak resonance of the effective permittivity as the bias current increases. Both effects are intrinsically linked to the influence of the polymer matrix on the magnetic structure and properties of the microwires. A discussion of these results is proposed in terms of two competing effects of the bias current, i.e., the induced additional effective field in the plane normal to the wire axis and the stress relief from Joule heating.

  19. Second order finite volume scheme for Maxwell's equations with discontinuous electromagnetic properties on unstructured meshes

    NASA Astrophysics Data System (ADS)

    Ismagilov, Timur Z.

    2015-02-01

    This paper presents a second order finite volume scheme for numerical solution of Maxwell's equations with discontinuous dielectric permittivity and magnetic permeability on unstructured meshes. The scheme is based on Godunov scheme and employs approaches of Van Leer and Lax-Wendroff to increase the order of approximation. To keep the second order of approximation near dielectric permittivity and magnetic permeability discontinuities a novel technique for gradient calculation and limitation is applied near discontinuities. Results of test computations for problems with linear and curvilinear discontinuities confirm second order of approximation. The scheme was applied to modelling propagation of electromagnetic waves inside photonic crystal waveguides with a bend.

  20. Electromagnetic properties of massive neutrinos in low-energy elastic neutrino-electron scattering

    NASA Astrophysics Data System (ADS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2017-03-01

    A thorough account of electromagnetic interactions of massive neutrinos in the theoretical formulation of low-energy elastic neutrino-electron scattering is given. The formalism of neutrino charge, magnetic, electric, and anapole form factors defined as matrices in the mass basis is employed under the assumption of three-neutrino mixing. The flavor change of neutrinos traveling from the source to the detector is taken into account and the role of the source-detector distance is inspected. The effects of neutrino flavor-transition millicharges and charge radii in the scattering experiments are pointed out.

  1. Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

    NASA Astrophysics Data System (ADS)

    Heng, Hang; Wang, Rong

    2017-01-01

    Optical metamaterials can concentrate light into extremely tiny volumes to enhance their interaction with quantum objects. In this paper, a cylindrical microcavity based on the Au-dielectric-Au sandwiched structure is proposed. Numerical study shows that the cylindrical microcavity has the strong ability of localizing light and confining 103- 104-fold enhancement of the electromagnetic energy density, which contains the most energy of the incoming light. The enhancement factor of energy density G inside the cavity shows the regularities as the change in the thickness of the dielectric slab, dielectric constant, and the radius of gold disk. At the normal incidence of electromagnetic radiation, the obtained reflection spectra operate in the range from 4.8 μm to 6 μm and with the absorption efficiency C (C=1-R min), which can reach 99% by optimizing the structure's geometry parameters, and the dielectric constant. Due to the symmetry of the cylindrical microcavities, this structure is insensitive to the polarization of the incident wave. The proposed optical metamaterials will have potential applications in the surface enhanced spectroscopy, new plasmonic detectors, bio-sensing, solar cells, etc.

  2. Flexible and Thermostable Graphene/SiC Nanowire Foam Composites with Tunable Electromagnetic Wave Absorption Properties.

    PubMed

    Han, Meikang; Yin, Xiaowei; Hou, Zexin; Song, Changqing; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2017-04-05

    Three-dimensional (3D) flexible foams consisting of reduced graphene oxides (rGO) and in situ grown SiC nanowires (NWs) were prepared using freeze-drying and carbothermal reduction processes. By means of incorporating SiC nanowires into rGO foams, both the thermostability and electromagnetic absorption of the composites were improved. It was demonstrated that rGO/SiC NW foams were thermostable beyond ∼630 °C (90% weight retention in air atmosphere). As expected, rGO/SiC NW foams in the poly(dimethylsiloxane) matrix achieved effective absorption in the entire X-band (8.2-12.4 GHz) with a thinner thickness (3 mm) in comparison with those of the pure rGO foams. It is revealed that SiC nanowires with abundant stacking faults, twinning interfaces, and bridged junctions play an important role in the enhanced electromagnetic absorption performance, in addition to the contribution of interconnected graphene networks. Hierarchical rGO/SiC NW foams not only are efficient absorbers in the critical environments but also can be applied in photocatalytic and thermal-management fields.

  3. Excellent electromagnetic absorption properties of poly(3,4-ethylenedioxythiophene)-reduced graphene oxide-Co3O4 composites prepared by a hydrothermal method.

    PubMed

    Liu, Pan-Bo; Huang, Ying; Sun, Xu

    2013-12-11

    The ternary composites of poly(3,4-ethylenedioxythiophene)-reduced graphene oxide-Co3O4 (PEDOT-RGO-Co3O4) were synthesized and the electromagnetic absorption property of the composites was investigated. The structure of the composites was characterized with Fourier-transform infrared spectra, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscope. The electromagnetic parameters indicate the enhanced electromagnetic absorption property of the composites was attributed to the better impedance matching. On the basis of the above characterization, an electromagnetic complementary theory was proposed to explain the impedance matching. It can be found that the maximum reflection loss of PEDOT-RGO-Co3O4 can reach -51.1 dB at 10.7 GHz, and the bandwidth exceeding -10 dB is 3.1 GHz with absorber thickness of 2.0 mm. Therefore, the PEDOT-RGO-Co3O4 composites, with such excellent electromagnetic absorption properties and wide absorption bandwidth, can be used as a new kind of candidate for microwave absorbing materials.

  4. Flow-field differences and electromagnetic-field properties of air and N2 inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Yu, Minghao; Yamada, Kazuhiko; Takahashi, Yusuke; Liu, Kai; Zhao, Tong

    2016-12-01

    A numerical model for simulating air and nitrogen inductively coupled plasmas (ICPs) was developed considering thermochemical nonequilibrium and the third-order electron transport properties. A modified far-field electromagnetic model was introduced and tightly coupled with the flow field equations to describe the Joule heating and inductive discharge phenomena. In total, 11 species and 49 chemical reactions of air, which include 5 species and 8 chemical reactions of nitrogen, were employed to model the chemical reaction process. The internal energy transfers among translational, vibrational, rotational, and electronic energy modes of chemical species were taken into account to study thermal nonequilibrium effects. The low-Reynolds number Abe-Kondoh-Nagano k-ɛ turbulence model was employed to consider the turbulent heat transfer. In this study, the fundamental characteristics of an ICP flow, such as the weak ionization, high temperature but low velocity in the torch, and wide area of the plasma plume, were reproduced by the developed numerical model. The flow field differences between the air and nitrogen ICP flows inside the 10-kW ICP wind tunnel were made clear. The interactions between the electromagnetic and flow fields were also revealed for an inductive discharge.

  5. Effect of Nd-doping on structure and microwave electromagnetic properties of BiFeO3

    NASA Astrophysics Data System (ADS)

    Liu, Sheng; Luo, Heng; Yan, Shuoqing; Yao, Lingling; He, Jun; Li, Yuhan; He, Longhui; Huang, Shengxiang; Deng, Lianwen

    2017-03-01

    The single-phase Bi1-xNdxFeO3 (x=0, 0.05, 0.10, 0.15, 0.20) were synthesized by the sol-gel method. Their crystal structure and microwave electromagnetic property in the frequency range of 2-18 GHz were investigated. The XRD patterns and Raman spectra showed that structural transition from rhombohedral (x=0, 0.05, 0.1) to triclinic (x=0.15) and tetragonal structure (x=0.20) appeared in the Bi1-xNdxFeO3. Electromagnetic measurement suggested that both microwave permeability μ‧ and magnetic loss tanδm increased remarkably over 2-18 GHz by doping Nd. Strong dielectric loss peak was observed on the samples of Bi1-xNdxFeO3 (x=0.15) and Bi1-xNdxFeO3 (x=0.2). Results show that Nd substitution is an effective way to push BiFeO3 to become microwave absorbing materials with high performance.

  6. Study of mechanical-magnetic and electromagnetic properties of PZT/Ni film systems by a novel bulge technique

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Zhou, W.; Ding, J.; Xiao, M.; Yu, Z. J.; Xu, H.; Mao, W. G.; Pei, Y. M.; Li, F. X.; Feng, X.; Fang, D. N.

    2017-02-01

    A novel multiple functional bulge apparatus was designed to study the mechanical-electronic-magnetic characteristics of electromagnetic materials. The elastic modulus difference effect of Ni thin film was observed and it was about 22.16% in the demagnetized and magnetization saturated states. The mechanical-magnetic behaviors of Ni and lead-titanate zirconate (PZT)/Ni films were in-situ measured by using the new bulge systems, respectively. The evolutions of three key material properties in hysteresis loop including saturation magnetization, remanent magnetization and coercive field were discussed in detail, respectively. The mechanisms of mechanical-magnetic coupled behaviors of Ni and PZT/Ni films were analyzed with the aid of the competitive relationship of stress and magnetization. Similarly, the electronic-magnetic characteristics of PZT/Ni films were in-situ measured by using this experimental system. The evolution of saturated magnetization, remanent magnetization and coercive field Kerr signals were discussed with the magneto-elastic anisotropy energy point. In this paper, a suitable mechanical-electronic-magnetic bulge measurement system was established, which would provide a good choice for further understanding the multi field coupling characteristics of electromagnetic film materials.

  7. Electromagnetic momentum and the energy–momentum tensor in a linear medium with magnetic and dielectric properties

    SciTech Connect

    Crenshaw, Michael E.

    2014-04-15

    In a continuum setting, the energy–momentum tensor embodies the relations between conservation of energy, conservation of linear momentum, and conservation of angular momentum. The well-defined total energy and the well-defined total momentum in a thermodynamically closed system with complete equations of motion are used to construct the total energy–momentum tensor for a stationary simple linear material with both magnetic and dielectric properties illuminated by a quasimonochromatic pulse of light through a gradient-index antireflection coating. The perplexing issues surrounding the Abraham and Minkowski momentums are bypassed by working entirely with conservation principles, the total energy, and the total momentum. We derive electromagnetic continuity equations and equations of motion for the macroscopic fields based on the material four-divergence of the traceless, symmetric total energy–momentum tensor. We identify contradictions between the macroscopic Maxwell equations and the continuum form of the conservation principles. We resolve the contradictions, which are the actual fundamental issues underlying the Abraham–Minkowski controversy, by constructing a unified version of continuum electrodynamics that is based on establishing consistency between the three-dimensional Maxwell equations for macroscopic fields, the electromagnetic continuity equations, the four-divergence of the total energy–momentum tensor, and a four-dimensional tensor formulation of electrodynamics for macroscopic fields in a simple linear medium.

  8. Electromagnetic nonuniformly correlated beams.

    PubMed

    Tong, Zhisong; Korotkova, Olga

    2012-10-01

    A class of electromagnetic sources with nonuniformly distributed field correlations is introduced. The conditions on source parameters guaranteeing that the source generates a physical beam are derived. It is shown that the new sources are capable of producing beams with polarization properties that evolve on propagation in a manner much more complex compared to the well-known electromagnetic Gaussian Schell-model beams.

  9. Influence of frequency, grade, moisture and temperature on Green River oil shale dielectric properties and electromagnetic heating processes

    SciTech Connect

    Hakala, J. Alexandra; Stanchina, William; Soong, Yee; Hedges, Sheila

    2011-01-01

    Development of in situ electromagnetic (EM) retorting technologies and design of specific EM well logging tools requires an understanding of various process parameters (applied frequency, mineral phases present, water content, organic content and temperature) on oil shale dielectric properties. In this literature review on oil shale dielectric properties, we found that at low temperatures (<200° C) and constant oil shale grade, both the relative dielectric constant (ε') and imaginary permittivity (ε'') decrease with increased frequency and remain constant at higher frequencies. At low temperature and constant frequency, ε' decreases or remains constant with oil shale grade, while ε'' increases or shows no trend with oil shale grade. At higher temperatures (>200º C) and constant frequency, epsilon' generally increases with temperature regardless of grade while ε'' fluctuates. At these temperatures, maximum values for both ε' and ε'' differ based upon oil shale grade. Formation fluids, mineral-bound water, and oil shale varve geometry also affect measured dielectric properties. This review presents and synthesizes prior work on the influence of applied frequency, oil shale grade, water, and temperature on the dielectric properties of oil shales that can aid in the future development of frequency- and temperature-specific in situ retorting technologies and oil shale grade assay tools.

  10. Methodology for the analysis of the impact of the forging parameters on metallurgy and mechanical properties in case of solid electromagnetic manufactured parts

    NASA Astrophysics Data System (ADS)

    Borsenberger, Marc; Baudouin, Cyrille; Benabou, Abdelkader; Bigot, Régis; Faverolle, Pierre; Mipo, Jean-Claude

    2016-10-01

    For electromagnetic applications the microstructure and the final mechanical state are key parameters. These can be obtained by a judicious choice of the material, a particular design like laminated steels but also through the determination and the mastering of the fabrication process. This present paper contains a brief introduction to electromagnetics and the qualification of a "good" electromagnetic quality. Then the article highlights, based on literature, first the influence of the process parameters on microstructure, mechanical state and secondly the impact these properties themselves on magnetic properties. Eventually, a methodology is proposed in order to predict the functional behavior of a part in its final system, taking into account its manufacturing process. The academic study case presented here can illustrate such a methodology. This kind of methodology includes in particular experimental tests, physical analysis and numerical modeling.

  11. Calculation of the Bulk Electromagnetic Properties of Thunderclouds Using a Two-Space Scattering Formalism

    NASA Technical Reports Server (NTRS)

    Phanord, Dieudonne D.; Koshak, William J.; Solakiewicz, Richard J.; Blakeslee, Richard J.

    1998-01-01

    A two-space scatterer formalism and equivalent medium approach of Twersky are used to obtain formulae for the bulk electromagnetic parameters of a thundercloud medium that is illuminated by lightning optical emissions. A modified WKB approximation is applied to derive the two-space scattering amplitude. Optical constants of dry air, moist atmosphere, and water,.are inserted into the formulae to generate numerical values via iteration. The two-space scatterer formalism results are close to those obtained from free- or sin-le-space formalisms for the dilute case. The numerical values of the bulk parameters are required to successfully transform the scattering problem to that of an equivalent obstacle excited by an incident wave traveling in K - space but radiating in k(sub 1) -space.

  12. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption

    PubMed Central

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-01-01

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches −42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm. PMID:27762327

  13. Low-Temperature Sintering and Electromagnetic Properties of NiCuZn/CaTiO3 Composites

    NASA Astrophysics Data System (ADS)

    Yang, Haibo; Yang, Yanyan; Lin, Ying; Zhu, Jianfeng; Wang, Fen

    2012-04-01

    Dense CaTiO3/Ni0.37Cu0.20Zn0.43Fe1.92O3.88 (CTO/NiCuZn) composites were prepared by the conventional solid-state reaction method and sintered at 950°C. The phase compositions and surface morphologies of the composites were investigated using x-ray diffraction and scanning electron microscopy, respectively. The dielectric and magnetic properties of the composites were also investigated. The results show that the CTO/NiCuZn composites possess high dielectric constants and permeabilities, which can be used in high-frequency communications for capacitor-inductor integrating devices such as electromagnetic interference filters and antennas. With increasing NiCuZn concentration, the permeabilities of the CTO/NiCuZn composites increase, while the dielectric constants and cutoff frequencies decrease.

  14. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption.

    PubMed

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-10-20

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches -42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm.

  15. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption

    NASA Astrophysics Data System (ADS)

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-10-01

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches ‑42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm.

  16. Propagation properties of partially coherent electromagnetic hyperbolic-sine-Gaussian vortex beams through non-Kolmogorov turbulence.

    PubMed

    Huang, Yongping; Wang, Fanhou; Gao, Zenghui; Zhang, Bin

    2015-01-26

    Propagation properties of partially coherent electromagnetic hyperbolic-sine-Gaussian (PCESHG) vortex beams through non-Kolmogorov atmospheric turbulence, including the spectral degree of polarization and evolution behavior of coherent vortices and average intensity are investigated in detail by using the extended Huygens-Fresnel principle and the spatial power spectrum of the refractive index of non-Kolmogorov turbulence. It is shown that the motion, creation and annihilation of the coherent vortices of PCESHG vortex beams in non-Kolmogorov turbulence may appear with the increasing propagation distance, and the distance for the conservation of the topological charge depends on the turbulence parameters and beam parameters. In additions, the evolution behavior of coherent vortices, average intensity and spectral degree of polarization vary significantly for different values of the generalized exponent parameter and the generalized refractive-index structure parameter of non-Kolmogorov turbulence, and the beam parameters as well as the propagation distance.

  17. Electromagnetic Properties of (Gd, Y)Ba2Cu3Ox Superconducting Tapes With High Levels of Zr Addition

    SciTech Connect

    Liu, Y; Yao, Y; Chen, Y; Khatri, ND; Liu, J; Galtsyan, E; Lei, C; Selvamanickam, V

    2013-06-01

    The dependence of the critical current density (J(c)) on the orientation of applied magnetic fields was studied in Zr-doped (Gd, Y)Ba2Cu3Ox tapes fabricated by metal organic chemical vapor deposition. The in-field performance of J(c) of (Gd, Y)Ba2Cu3Ox tapes with Zr-doping levels of 7.5-30 at.% was investigated up to 5 T over a temperature range of 40-77 K. The highest critical currents (I-c) at H parallel to c and the highest values of minimum Ic in angular dependence measurements were achieved in the tapes with 20% Zr doping over a broad range of temperature and magnetic field conditions measured. The electromagnetic properties have been related to the changes in BaZrO3 content and microstructure.

  18. Mechanical and electromagnetic properties of 3D printed hot pressed nanocarbon/poly(lactic) acid thin films

    NASA Astrophysics Data System (ADS)

    Kotsilkova, R.; Ivanov, E.; Todorov, P.; Petrova, I.; Volynets, N.; Paddubskaya, A.; Kuzhir, P.; Uglov, V.; Biró, I.; Kertész, K.; Márk, G. I.; Biró, L. P.

    2017-02-01

    We constructed a new type of light-weight, nanocarbon based thin film material having good mechanical properties, thermal stability, and electromagnetic shielding efficiency. Our method, 3D printing combined with hot pressing, is a cheap and industrially upscalable process. First a sandwich structure was created by layer-to-layer deposition of alternating 100 μm thick nanocarbon containing plastic layers and 100 μm thick pristine plastic layers, repeated as building blocks. The 3D printed samples were hot pressed to obtain thin films of 10-30 μm thickness. We used a commercial nanocarbon 3D printing filament (Black Magic). TEM investigations revealed the nanocarbon filler to be a mixture of graphene sheets, short carbon nanotubes, fishbone nanotubes, graphitic nanoparticles, and carbon black. Small-angle X-ray scattering and X-ray diffraction studies showed some amorphization of the nanocarbon filler as a consequence of the hot pressing. The nanoindentation hardness, nanoscratch hardness, and Young's modulus increase gradually by increasing the number of layers in the films, due to an increase of the amount of nanocarbon filler. Microwave absorption also increases continuously with the number of nanocarbon layers, reaching 40% for 3 nanocarbon layers. We demonstrate that unlike most conventional composites loaded with nanocarbons having pronounced dielectric properties, when the real part of permittivity Re(ɛ) is much higher than its imaginary part Im(ɛ) at high frequencies, a combination of 3D printing and hot pressing allows the fabrication of composites with Re ɛ ≈ Im ɛ in a very broad frequency range (0.2-0.6 THz). Our new 3D printed—hot pressed thin films may compete with the CVD graphene sandwiches in electromagnetic shielding applications because of their easier processability and low cost.

  19. Electromagnetic structure of light nuclei

    SciTech Connect

    Pastore, Saori

    2016-03-25

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  20. Electromagnetic properties of flake-shaped Fe-Si alloy particles prepared by ball milling

    NASA Astrophysics Data System (ADS)

    Cao, Lei; Jiang, Jian-Tang; Wang, Zeng-Quan; Gong, Yuan-Xun; Liu, Chao; Zhen, Liang

    2014-11-01

    Flake-shaped Fe-Si alloy particles with high aspect ratios were fabricated by ball milling commercially available Fe-Si powder, aiming to fabricate high-performance microwave absorbing fillers for coatings applied in 1-4 GHz range. To compare with spherical particles, higher permittivity and permeability was observed by using flaky particles as fillers. High aspect ratios contributed to an enhanced dielectric relaxation in the 1-4 GHz band, resulting in an increased permittivity. The thin thickness together with the high resistivity of Fe-Si flakes was believed to be helpful for suppressing the effect of eddy current and thus lead to an increase in the permeability. The electromagnetic wave absorbing (EMA) performances were observed to be enhanced. With a thin thickness of 2 mm, a wide absorption band with a minimum reflection loss of -12 dB was achieved in 1-4 GHz range, when using 75 wt% of flaky Fe-Si particles as fillers. The study indicated that flake-shaped Fe-Si particles were a promising candidate for EMA materials in L and S bands.

  1. Electromagnetic and microwave absorption properties of (Co2+-Si4+) substituted barium hexaferrites and its polymer composite

    NASA Astrophysics Data System (ADS)

    Abbas, S. M.; Chatterjee, R.; Dixit, A. K.; Kumar, A. V. R.; Goel, T. C.

    2007-04-01

    The electromagnetic (EM) and microwave absorption properties of (Co2+-Si4+) substituted barium hexaferrite compositions BaCox2+Fey+2Six+y4+Fe12-2x-2y+3O19 (x =0.9 and y =0.0, 0.05, and 0.2) and its polymer composites prepared from hexaferrite, polyaniline, and carbon powders dispersed in polyurethane matrix have been investigated at the microwave frequency range of the X band (8.2-12.4GHz). The hexaferrite compositions were synthesized by solid-state reaction technique, whereas polyaniline, by chemical route. The permeabilities of a ferrite are drastically reduced at higher gigahertz frequencies. The permittivities, however, can be enhanced by appropriate choice of composition and processing temperature. In the present ferrite composition, silicon content is taken in excess so as to convert some of the Fe3+ ions to Fe2+ ions. This conversion has been shown to enhance EM and absorption properties. Mössbauer spectroscopy on the samples establishes that addition of excess Si4+ converts some of the Fe3+ to Fe2+. The sintered ferrites have shown resonance phenomena, but the composites do not. The EM parameters ɛ', ɛ″, μ', and μ″ were measured using a vector network analyzer (Agilent, model PNA E8364B). These measured EM parameters were used to determine the absorption spectra at different sample thicknesses based on a model of a single layered plane wave absorber backed by a perfect conductor. The sintered ferrite composition (x =0.9 and y =0.05) showed the best absorption properties [a minimum reflection loss of -17.7to-14.3dB over the whole frequency range of the X band (8.2-12.4) for a sample thickness of just 0.8mm], and it is used in the composite absorbers in powder form along with other constituents. The optimized composite absorber has shown dielectric constant ɛ'˜11.5, dielectric loss ɛ″˜2.3, and a minimum reflection loss of -29dB at 10.97GHz with the -20dB bandwidth over the frequency range of 9.7-12.2GHz for a sample thickness of 2.0mm. The

  2. Multipolar electromagnetic fields around neutron stars: exact vacuum solutions and related properties

    NASA Astrophysics Data System (ADS)

    Pétri, J.

    2015-06-01

    The magnetic field topology in the surrounding of neutron stars is one of the key questions in pulsar magnetospheric physics. A very extensive literature exists about the assumption of a dipolar magnetic field but very little progress has been made in attempts to include multipolar components in a self-consistent way. In this paper, we study the effect of multipolar electromagnetic fields anchored in the star. We give exact analytical solutions in closed form for any order l and apply them to the retarded point quadrupole (l = 2), hexapole (l = 3) and octopole (l = 4), a generalization of the retarded point dipole (l = 1). We also compare the Poynting flux from each multipole and show that the spin-down luminosity depends on the ratio R/rL, R being the neutron star radius and rL the light-cylinder radius. Therefore the braking index also depends on R/rL. As such multipole fields possess very different topology, most importantly smaller length scales compared to the dipolar field, especially close to the neutron star, we investigate the deformation of the polar caps induced by these multipolar fields. Such fields could have a strong impact on the interpretation of the pulsed radio emission suspected to emanate from these polar caps as well as on the inferred geometry deduced from the high-energy light-curve fitting and on the magnetic field strength. Discrepancies between the two-pole caustic model and our new multipole caustic model are emphasized with the quadrupole field. To this respect, we demonstrate that working with only a dipole field can be very misleading.

  3. Electromagnetic property of SiO2-coated carbonyl iron/polyimide composites as heat resistant microwave absorbing materials

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-02-01

    Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated carbonyl iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from -25 dB to -33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.

  4. Improved microwave absorption and electromagnetic properties of BaFe12O19-poly(vinylidene fluoride) composites by incorporating reduced graphene oxides

    NASA Astrophysics Data System (ADS)

    He, Hongcai; Luo, Feifei; Qian, Neng; Wang, Ning

    2015-02-01

    Three-phase composites of poly(vinylidene fluoride)-BaFe12O19-reduced graphene oxide (PVDF-BFO-RGO) were synthesized by a facile wet chemical method and hot-pressing approach. The phase structure, topography of the hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectra. Influence of RGO on their electromagnetic properties was investigated. Especially, improved microwave absorption and electromagnetic properties of BaFe12O19-PVDF composites by incorporating RGO were obtained and studied. The PVDF/BFO/RGO sample with m(RGO):m(BFO) = 5:100 shows the best microwave absorption properties with a minimum RL = -32 dB at 11 GHz and with the bandwidth less than -20 dB from 9.6 to 12.8 GHz. The composites were believed to have potential applications as the microwave absorber.

  5. Irradiation response of commercial, high-Tc superconducting tapes: Electromagnetic transport properties

    DOE PAGES

    Gapud, A. A.; Greenwood, N. T.; Alexander, J. A.; ...

    2015-07-01

    Effects of low dose irradiation on the electrical transport current properties of commercially available high-temperature superconducting, coated-conductor tapes were investigated, in view of potential applications in the irradiative environment of fusion reactors. Three different tapes, each with unique as-grown flux-pinning structures, were irradiated with Au and Ni ions at energies that provide a range of damage effects, with accumulated damage levels near that expected for conductors in a fusion reactor environment. Measurements using transport current determined the pre- and post-irradiation resistivity, critical current density, and pinning force density, yielding critical temperatures, irreversibility lines, and inferred vortex creep rates. Results showmore » that at the irradiation damage levels tested, any detriment to as-grown pre-irradiation properties is modest; indeed in one case already-superior pinning forces are enhanced, leading to higher critical currents.« less

  6. Electromagnetic Nondestructive Evaluation of Wire Insulation and Models of Insulation Material Properties

    NASA Technical Reports Server (NTRS)

    Bowler, Nicola; Kessler, Michael R.; Li, Li; Hondred, Peter R.; Chen, Tianming

    2012-01-01

    Polymers have been widely used as wiring electrical insulation materials in space/air-craft. The dielectric properties of insulation polymers can change over time, however, due to various aging processes such as exposure to heat, humidity and mechanical stress. Therefore, the study of polymers used in electrical insulation of wiring is important to the aerospace industry due to potential loss of life and aircraft in the event of an electrical fire caused by breakdown of wiring insulation. Part of this research is focused on studying the mechanisms of various environmental aging process of the polymers used in electrical wiring insulation and the ways in which their dielectric properties change as the material is subject to the aging processes. The other part of the project is to determine the feasibility of a new capacitive nondestructive testing method to indicate degradation in the wiring insulation, by measuring its permittivity.

  7. Irradiation response of commercial, high-Tc superconducting tapes: Electromagnetic transport properties

    SciTech Connect

    Gapud, A. A.; Greenwood, N. T.; Alexander, J. A.; Khan, A.; Leonard, K. J.; Aytug, T.; List III, F. A.; Rupich, M. W.; Zhang, Y.

    2015-07-01

    Effects of low dose irradiation on the electrical transport current properties of commercially available high-temperature superconducting, coated-conductor tapes were investigated, in view of potential applications in the irradiative environment of fusion reactors. Three different tapes, each with unique as-grown flux-pinning structures, were irradiated with Au and Ni ions at energies that provide a range of damage effects, with accumulated damage levels near that expected for conductors in a fusion reactor environment. Measurements using transport current determined the pre- and post-irradiation resistivity, critical current density, and pinning force density, yielding critical temperatures, irreversibility lines, and inferred vortex creep rates. Results show that at the irradiation damage levels tested, any detriment to as-grown pre-irradiation properties is modest; indeed in one case already-superior pinning forces are enhanced, leading to higher critical currents.

  8. Electromagnetic properties of water on GHz frequencies for medicine tasks and metamaterial applications

    NASA Astrophysics Data System (ADS)

    Pavlov, N. D.; Baloshin, Y. A.

    2015-11-01

    In problems of modern radio physics and medicine it is important to know dielectric permittivity of liquids. Dispersion characteristics of water in UHF frequency band can be used to analyze the states of biological objects, and also to construct materials (metamanerials). The present work is intended to study the material properties of water in UHF frequency band based on two different techniques: Nicolson-Ross-Weir (NRW) [1] and the Active Nearfield Diagnostics [2].

  9. Theoretical study of turbulent channel flow: Bulk properties, pressure fluctuations, and propagation of electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Hartke, G. J.; Battaglia, A.; Chasnov, J.; Albrecht, G. F.

    1988-01-01

    In this paper, we apply two theoretical turbulence models, DIA and the recent GISS model, to study properties of a turbulent channel flow. Both models provide a turbulent kinetic energy spectral function E(k) as the solution of a non-linear equation; the two models employ the same source function but different closures. The source function is characterized by a rate n sub s (k) which is derived from the complex eigenvalues of the Orr--Sommerfeld (OS) equation in which the basic flow is taken to be of a Poiseuille type. The O--S equation is solved for a variety of Reynolds numbers corresponding to available experimental data. A physical argument is presented whereby the central line velocity characterizing the basic flow, U0 sup L, is not to be identified with the U0 appearing in the experimental Reynolds number. The theoretical results are compared with two types of experimental data: (1) turbulence bulk properties, and (2) properties that depend stongly on the structure of the turbulence spectrun at low wave numbers. The only existing analytical expression for Pi (k) cannot be used in the present case because it applies to the case of a flat plate, not a finite channel.

  10. New Soft Magnetic Composites for electromagnetic applications with improved mechanical properties

    NASA Astrophysics Data System (ADS)

    Ferraris, Luca; Pošković, Emir; Franchini, Fausto

    2016-05-01

    The chance to move from 2D to 3D approach in the design of the electrical machines is made possible by the availability of Soft Magnetic Composites (SMC), iron based powders, insulated and pressed to realize shapes otherwise impossible with the traditional lamination sheets technology. Some commercial products are available on the market as "ready to press" powders, which presents good magnetic and energetic properties but are sometimes weak under the mechanical point of view; other products aim at improving this aspect but with considerable process complications and relative cost. The experience of the Authors in the realization of bonded magnets with the adoption of selected organic resins has been partly transferred in the research field of the SMC in order to investigate the possibility to obtain good mechanical properties maintaining the magnetic characteristics of the Insulated Iron Powder Compounds (I.I.P.C.) taken as reference. The paper presents the activity that has been carried out in the realization of SMC mixing iron powders and phenolic resin, in different weight percentages and mold pressures. The obtained results are considered satisfactory under the point of view of the compromise between magnetic and mechanical properties, considering also that the required productive process is simpler. The comparison of the obtained results with those related to commercial products encourages to carry on the research, also because of the reduced cost of the proposed SMC at parity (or better) performance.

  11. Electromagnetic and absorbing property of CIPs/resin composite using the 3D forming process

    NASA Astrophysics Data System (ADS)

    Xu, Yonggang; Liang, Zichang; Wang, Xiaobing; Yuan, Liming; Li, Xinghao

    2016-08-01

    The absorbing composite filled with the flaky carbonyl iron particles (CIPs) were prepared using a three-dimensional (3D) forming process, in which the forming powder was fabricated using a milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer, and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 4-18 GHz. With the variable thickness was set, the reflection loss (RL) was simulated to analyze the absorbing property of the composite. The results showed that the forming powder was uniformly dispersed in the absorber, and the saturation magnetization and the grain structure of the CIPs in the forming powder nearly did not change in the milling process. With the same volume content CIPs added, the average permittivity and the imaginary permeability of the samples added the powder was smaller than the directly mixing sample due to the aggregation effect. The RL results showed that the absorbing composites using the 3D forming process with thickness 6 or 8 mm had an better absorbing property (minimum RL -13.58 and -21.85 dB) in 4-18 GHz.

  12. Theoretical study of turbulent channel flow - Bulk properties, pressure fluctuations, and propagation of electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Hartke, G. J.; Battaglia, A.; Chasnov, J.; Albrecht, G. F.

    1990-01-01

    In this paper, we apply two theoretical turbulence models, DIA and the recent GISS model, to study properties of a turbulent channel flow. Both models provide a turbulent kinetic energy spectral function E(k) as the solution of a non-linear equation; the two models employ the same source function but different closures. The source function is characterized by a rate n sub s (k) which is derived from the complex eigenvalues of the Orr-Sommerfeld (OS) equation in which the basic flow is taken to be of a Poiseuille type. The O-S equation is solved for a variety of Reynolds numbers corresponding to available experimental data. A physical argument is presented whereby the central line velocity characterizing the basic flow, U0 sup L, is not to be identified with the U0 appearing in the experimental Reynolds number. The theoretical results are compared with two types of experimental data: (1) turbulence bulk properties, and (2) properties that depend strongly on the structure of the turbulence spectrum at low wave numbers. The only existing analytical expression for Pi (k) cannot be used in the present case because it applies to the case of a flat plate, not a finite channel.

  13. Influence of shear cutting parameters on the electromagnetic properties of non-oriented electrical steel sheets

    NASA Astrophysics Data System (ADS)

    Weiss, H. A.; Leuning, N.; Steentjes, S.; Hameyer, K.; Andorfer, T.; Jenner, S.; Volk, W.

    2017-01-01

    Mechanical stress occurring during the manufacturing process of electrical machines detrimentally alters the magnetic properties (iron losses and magnetizability). This affects the efficiency and performance of the machine. Improvement of the manufacturing process in terms of reduced magnetic property deterioration enables the full potential of the magnetic materials to be exploited, and as a result, the performance of the machine to be improved. A high quantity of electrical machine components is needed, with shear cutting (punching, blanking) being the most efficient manufacturing technology. The cutting process leads to residual stresses inside the non-oriented electrical sheet metal, resulting in increased iron losses. This paper studies the residual stresses induced by punching with different shear cutting parameters, taking a qualitative approach using finite element analysis. In order to calibrate the finite element analysis, shear cutting experiments are performed. A single sheet tester analysis of the cut blanks allows the correlation between residual stresses, micro hardness measurements, cutting surface parameters and magnetic properties to be studied.

  14. Electromagnetic methods for measuring materials properties of cylindrical rods and array probes for rapid flaw inspection

    SciTech Connect

    Sun, Haiyan

    2005-01-01

    The case-hardening process modifies the near-surface permeability and conductivity of steel, as can be observed through changes in alternating current potential drop (ACPD) along a rod. In order to evaluate case depth of case hardened steel rods, analytical expressions are derived for the alternating current potential drop on the surface of a homogeneous rod, a two-layered and a three-layered rod. The case-hardened rod is first modeled by a two-layer rod that has a homogeneous substrate with a single, uniformly thick, homogeneous surface layer, in which the conductivity and permeability values differ from those in the substrate. By fitting model results to multi-frequency ACPD experimental data, estimates of conductivity, permeability and case depth are found. Although the estimated case depth by the two-layer model is in reasonable agreement with the effective case depth from the hardness profile, it is consistently higher than the effective case depth. This led to the development of the three-layer model. It is anticipated that the new three-layered model will improve the results and thus makes the ACPD method a novel technique in nondestructive measurement of case depth. Another way to evaluate case depth of a case hardened steel rod is to use induction coils. Integral form solutions for an infinite rod encircled by a coaxial coil are well known, but for a finite length conductor, additional boundary conditions must be satisfied at the ends. In this work, calculations of eddy currents are performed for a two-layer conducting rod of finite length excited by a coaxial circular coil carrying an alternating current. The solution is found using the truncated region eigenfunction expansion (TREE) method. By truncating the solution region to a finite length in the axial direction, the magnetic vector potential can be expressed as a series expansion of orthogonal eigenfunctions instead of as a Fourier integral. Closed-form expressions are derived for the electromagnetic

  15. TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. I. PROPERTIES OF A QUASI-KERR SPACETIME

    SciTech Connect

    Johannsen, Tim; Psaltis, Dimitrios E-mail: dpsaltis@email.arizona.ed

    2010-06-10

    According to the no-hair theorem, an astrophysical black hole is uniquely described by only two quantities, the mass and the spin. In this series of papers, we investigate a framework for testing the no-hair theorem with observations of black holes in the electromagnetic spectrum. We formulate our approach in terms of a parametric spacetime which contains a quadrupole moment that is independent of both mass and spin. If the no-hair theorem is correct, then any deviation of the black hole quadrupole moment from its Kerr value has to be zero. We analyze in detail the properties of this quasi-Kerr spacetime that are critical to interpreting observations of black holes and demonstrate their dependence on the spin and quadrupole moment. In particular, we show that the location of the innermost stable circular orbit and the gravitational lensing experienced by photons are affected significantly at even modest deviations of the quadrupole moment from the value predicted by the no-hair theorem. We argue that observations of black hole images, of relativistically broadened iron lines, as well as of thermal X-ray spectra from accreting black holes will lead in the near future to an experimental test of the no-hair theorem.

  16. Measurements of electromagnetic properties of LCT (Large Coil Task) coils in IFSMTF (International Fusion Superconducting Magnet Test Facility)

    SciTech Connect

    Shen, S.S.; Baylor, L.R.; Dresner, L.; Fehling, D.T.; Lubell, M.S.; Lue, J.W.; Luton, J.N.; McManamy, T.J.; Wilson, C.T.; Wintenberg, R.E.

    1987-01-01

    Participants in the international Large Coil Task (LCT) have designed, built, and tested six different toroidal field coils. Each coil has a 2.5- by 3.5-m, D-shaped bore and a current between 10 and 18 kA and is designed to demonstrate stable operation at 8 T, with a superimposed averaged pulsed field of 0.14 T in 1.0 s and simulated nuclear heating. Testing of the full six-coil toroidal array began early in 1986 and was successfully completed on September 3, 1987, in the International Fusion Superconducting Magnet Test Facility (IFSMTF) at Oak Ridge National Laboratory (ORNL). This paper summarizes electromagnetic properties of LCT coils measured in different modes of energization and fast dump. Effects of mutual coupling and induced eddy currents are analyzed and discussed. Measurements of the ac loss caused by the superimposed pulsed fields are summarized. Finally, the interpretation of the test results and their relevance to practical fusion are presented. 11 refs., 10 figs., 4 tab.

  17. Electromagnetic wave absorption properties of NiCoP alloy nanoparticles decorated on reduced graphene oxide nanosheets

    NASA Astrophysics Data System (ADS)

    Ye, Weichun; Fu, Jiajia; Wang, Qin; Wang, Chunming; Xue, Desheng

    2015-12-01

    NiCoP alloy nanoparticles supported on reduced graphene oxide (NiCoP/RGO) are synthesized by in situ co-reduction of Ni2+, Co2+ and graphene oxide (GO) with sodium hypophosphite in a one-pot reaction. This synthesis route is simple and can be used for industrial preparation. The different molar ratios of Ni/Co can be obtained by changing the molar ratio of their salts in the reaction bath. The effect of annealing temperature on the crystal structure of NiCoP alloys has been further investigated. After 500 °C annealing, NiCoP alloys exhibit good crystallinity. The as-prepared NiCoP/RGO composites demonstrate high dielectric constant and magnetic loss in the frequency range of 2-18 GHz due to the conductive and ferromagnetic behavior. Also, their coercivity and magnetization strength are decreased from magnetic measurement with the increase of Ni content. As the molar ratio of Ni/Co is 3:1, the maximum value of the reflection loss reaches to -17.84 dB. Furthermore, the NiCoP/RGO composites have better corrosion resistance than traditional iron series magnetic nanoparticles. It is expected that the composites with the thin, light-weighted and broadband absorbing and good anti-corrosion properties will have a great potential for electromagnetic wave absorption applications.

  18. Fabrication and evaluation of thin layer PVDF composites using MWCNT reinforcement: Mechanical, electrical and enhanced electromagnetic interference shielding properties

    NASA Astrophysics Data System (ADS)

    Bhaskara Rao, B. V.; Kale, Nikita; Kothavale, B. S.; Kale, S. N.

    2016-06-01

    Radar X-band electromagnetic interference shielding (EMS) is one of the prime requirements for any air vehicle coating; with limitations on the balance between strength and thickness of the EMS material. Nanocomposite of multiwalled-carbon-nanotubes (MWCNT) has been homogeneously integrated (0 - 9 wt%) with polymer, poly (vinylidene fluoride, PVDF) to yield 300 micron film. The PVDF + 9 wt% MWCNT sample of density 1.41 g/cm3 show specific shielding effectiveness (SSE) of 17.7 dB/(g/cm3) (99.6% EMS), with maintained hardness and improved conductivity. With multilayer stacking (900 microns) of these films of density 1.37 g/cm3, the sample showed increase in SSE to 23.3 dB/(g/cm3) (99.93% EMS). Uniform dispersion of MWCNTs in the PVDF matrix gives rise to increased conductivity in the sample beyond 5 wt% MWCNT reinforcement. The results are correlated to the hardness, reflection loss, absorption loss, percolation threshold, permittivity and the conductivity data. An extremely thin film with maximum EMS property is hence proposed.

  19. Electromagnetic properties of Fe53Ni47 and Fe53Ni47/Cu granular composite materials in the microwave range

    NASA Astrophysics Data System (ADS)

    Massango, Herieta; Tsutaoka, Takanori; Kasagi, Teruhiro

    2016-09-01

    The electromagnetic proprieties of Fe53Ni47 granular composite materials and Fe53Ni47/Cu hybrid granular composites have been studied by measuring the relative complex permeability and permittivity spectra as well as the ac electrical conductivity. In the Fe53Ni47 composite, the variation of the ac conductivity at 1 kHz with the particle volume content shows an insulator-metal transition at the percolation threshold at 61 vol% particle content. A negative permeability spectrum due to the magnetic resonance in Fe53Ni47 particles was observed in the 85 vol% composite. Meanwhile, the negative permittivity spectrum caused by the plasmoinc state of the percolated Fe53Ni47 particle clusters appears at 90 vol%. The Fe53Ni47/Cu hybrid composite containing 85 vol% of Fe53Ni47/Cu hybrid particle as filers shows the percolative metallic properties; the ac conductivity increases with increasing the Cu particle volume fraction in the Fe53Ni47/Cu particle system. The negative permittivity spectrum appears above the Cu particle volume fraction of 0.16; the double negative characteristic was observed at that of 0.20 and 0.24 hybrid composites in the frequency range from 300 MHz to 1.8 GHz in the absence of the external magnetic field.

  20. Substitution effect of (Mn, Ti) to the dielectric properties of barium-strontium hexaferrite for absorbing electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Repi, V. Vekky R.; Manaf, Azwar

    2012-07-01

    The objective of this work is to evaluate the ability of Mn-Ti substituted barium-strontium hexaferrite to absorb high frequency electromagnetic wave. To accomplish this objective, Mn-Ti substituted barium strontium hexaferrite of Ba0.5Sr0.5Fe12-x(Mn0.5Ti0.5)x with x = 0.1, x=0.3, x=0.5 were prepared through mechanical alloying route. Phase identification of the material obtained from XRD pattern indicating that the material is single phase for all variations of x. Coercivity and the remanent obtained by analyzing the hysteresis curve. The lowest coercivity at x = 0.5 for 77.86 kA/m but also lower the remanent of 0.088 kA/m. Dielectric properties of the material traced by calculating the value of permittivity and permeability of the material that was obtained with the parameters of the scattering vector network analyzer (VNA) in the 8GHz to 12GHz range.

  1. Substitution effect of (Mn, Ti) to the dielectric properties of barium-strontium hexaferrite for absorbing electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Vekky, V.; Repi, R.; Manaf, Azwar

    2012-06-01

    The objective of this work is to evaluate the ability of Mn-Ti substituted barium-strontium hexaferrite to absorb high frequency electromagnetic wave. To accomplish this objective, Mn-Ti substituted barium strontium hexaferrite of Ba0.5Sr0.5Fe12-x(Mn0.5Ti0.5)x with x = 0.1, x=0.3, x=0.5 were prepared through mechanical alloying route. Phase identification of the material obtained from XRD pattern indicating that the material is single phase for all variations of x. Coercivity and the remanent obtained by analyzing the hysteresis curve. The lowest coercivity at x = 0.5 for 77.86 kA/m but also lower the remanent of 0.088 kA/m. Dielectric properties of the material traced by calculating the value of permittivity and permeability of the material that was obtained with the parameters of the scattering vector network analyzer (VNA) in the 8GHz to 12GHz range.

  2. Light-Weight Silver Plating Foam and Carbon Nanotube Hybridized Epoxy Composite Foams with Exceptional Conductivity and Electromagnetic Shielding Property.

    PubMed

    Xu, Yu; Li, Ying; Hua, Wei; Zhang, Aiming; Bao, Jianjun

    2016-09-14

    Herein, light-weight and exceptionally conductive epoxy composite foams were innovatively fabricated for electromagnetic interference (EMI) shielding applications using multiwalled carbon nanotubes (MWCNTs) and 3D silver-coated melamine foam (SF) as conductive frameworks. A novel and nontraditional polymer microsphere was used to reduce the material density. The preformed, highly porous, and electrically conductive SF provided channels for fast electron transport. The MWCNTs were used to offset the decrease in conductive pathways due to the crystal defects of the silver layer and the insulating epoxy resin. Consequently, an exceptional conductivity of 253.4 S m(-1), a remarkable EMI shielding effectiveness of above 68 dB at 0.05-18 GHz, and a thermal conductivity of 0.305 W mK(-1) were achieved in these novel foams employing only 2 wt % of MWCNTs and 3.7 wt % of silver due to the synergistic effects that originated in the MWCNT and SF. These parameters are substantially higher than that achieved for the foam containing 2 wt % MWCNTs. Also, the SF exhibited little weakening in the foamability of the epoxy blends and the compression properties of resulting foams. All the results indicated that this effort provided a novel, simple, low-cost, and easily industrialized concept for fabricating light-weight, high-strength epoxy composite foams for high-performance EMI shielding applications.

  3. Mechanical Properties and Microstructure of Thin Plates of A6061 Wrought Aluminum Alloy Using Rheology Forging Process with Electromagnetic Stirring

    NASA Astrophysics Data System (ADS)

    Jin, Chul Kyu; Bolouri, Amir; Kang, Chung Gil

    2014-06-01

    We propose the possibility of fabricating A6061 thin plates using the rheology forging process. Electromagnetic stirring (EMS) is used to fabricate a semi-solid slurry. A thin plate is formed by injecting the slurry into the forging die. When the punch speed used to compress the slurry is low, turbulent flow occurs. When the punch speed is high, laminar flow occurs, and the solid and liquid phases move simultaneously. For a pressure of 150 MPa or below, incomplete filling behavior and cracks occur. For a pressure of 200 MPa or above, a durable formed product can be obtained. However, the differences between the mechanical properties according to the application of EMS and pressure are slight. The microstructure of the slurry without EMS has an unclear distinction between the liquid phase and solid phase. However, the microstructure of the thin plates formed by using this slurry has a clear distinction between the liquid and solid with respect to the spheroid shapes. The tensile strength and elongation for a thin plate formed with a punch speed of 300 mm/s and pressure of 250 MPa with EMS slurry are 169 MPa and 11.0 pct, respectively. After T6 heat treatment, the tensile strength improves to 305 MPa.

  4. Electromagnetic properties of ground-state and excited-state pseudoscalar mesons

    NASA Astrophysics Data System (ADS)

    Höll, A.; Krassnigg, A.; Maris, P.; Roberts, C. D.; Wright, S. V.

    2005-06-01

    The axial-vector Ward-Takahashi identity places constraints on particular properties of every pseudoscalar meson. For example, in the chiral limit all pseudoscalar mesons, except the Goldstone mode, decouple from the axial-vector current. Nevertheless, all neutral pseudoscalar mesons couple to two photons. The strength of the π0nγγ coupling, where n=0 denotes the Goldstone mode, is affected by the Abelian anomaly's continuum contribution. The effect is material for n≠0. The γ*πnγ* transition form factor, Tπn(Q2), is nonzero ∀n, and Tπn(Q2)≈(4π2/3)(fπn/Q2) at large Q2. For all pseudoscalars but the Goldstone mode, this leading contribution vanishes in the chiral limit. In this instance the ultraviolet power-law behavior is 1/Q4 for n≠0, and we find numerically Tπ1(Q2)≃(4π2/3)(-/Q4). This subleading power-law behavior is always present. In general its coefficient is not simply related to fπn. The properties of n≠0 pseudoscalar mesons are sensitive to the pointwise behavior of the long-range piece of the interaction between light quarks.

  5. Electromagnetic properties of neutron-rich nuclei adjacent to the Z = 50 shell closure

    NASA Astrophysics Data System (ADS)

    Rejmund, M.; Navin, A.; Biswas, S.; Lemasson, A.; Caamaño, M.; Clément, E.; Delaune, O.; Farget, F.; de France, G.; Jacquot, B.; Van Isacker, P.

    2016-02-01

    Low-lying high-spin yrast states in the exotic odd-odd isotopes 124-128Sb (Z = 51) and 118-128In (Z = 49), studied for the first time, show a striking difference in their observed γ-ray decay. With a single valence proton particle/hole occupying the g7/2 /g9/2 spin-orbit partners, dominant electric quadrupole transitions occur in Sb as opposed to magnetic dipole transitions in In. The observed properties are explained on the basis of general principles of symmetry and with large-scale shell-model calculations, and reveal novel aspects of the competition between the neutron-proton interaction and the like-nucleon pairing interaction.

  6. Electromagnetic properties of ground-state and excited-state pseudoscalar mesons

    SciTech Connect

    Hoell, A.; Krassnigg, A.; Wright, S.V.; Maris, P.; Roberts, C.D.

    2005-06-01

    The axial-vector Ward-Takahashi identity places constraints on particular properties of every pseudoscalar meson. For example, in the chiral limit all pseudoscalar mesons, except the Goldstone mode, decouple from the axial-vector current. Nevertheless, all neutral pseudoscalar mesons couple to two photons. The strength of the {pi}{sub n}{sup 0}{gamma}{gamma} coupling, where n=0 denotes the Goldstone mode, is affected by the Abelian anomaly's continuum contribution. The effect is material for n{ne}0. The {gamma}*{pi}{sub n}{gamma}* transition form factor, T{sub {pi}{sub n}}(Q{sup 2}), is nonzero for all n, and T{sub {pi}{sub n}}(Q{sup 2}){approx_equal}(4{pi}{sup 2}/3)(f{sub {pi}{sub n}}/Q{sup 2}) at large Q{sup 2}. For all pseudoscalars but the Goldstone mode, this leading contribution vanishes in the chiral limit. In this instance the ultraviolet power-law behavior is 1/Q{sup 4} for n{ne}0, and we find numerically T{sub {pi}{sub 1}}(Q{sup 2}){approx_equal}(4{pi}{sup 2}/3)(-/Q{sup 4}). This subleading power-law behavior is always present. In general its coefficient is not simply related to f{sub {pi}{sub n}}n. The properties of n{ne}0 pseudoscalar mesons are sensitive to the pointwise behavior of the long-range piece of the interaction between light quarks.

  7. Electromagnetic absorbing property of the flaky carbonyl iron particles by chemical corrosion process

    NASA Astrophysics Data System (ADS)

    Zheng, Dianliang; Liu, Ting; Zhou, Li; Xu, Yonggang

    2016-12-01

    The flaky carbonyl iron particles (CIPs) were prepared using a milling process at the first step, then the chemical corrosion process was done to optimize the particle shape. The particle morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2-18 GHz and the reflection loss (RL) was calculated. The results showed that the saturation magnetization value of the CIPs decreased as the CIPs was corroded to the small flakes in chemical corrosion process. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was more obvious and the intensity of the diffraction pattern was lower by corrosion. The permittivity and the permeability of the corroded milling CIPs was a little larger than the milling CIPs, it was due to the larger aspect ratio based on the fitting calculation process. At thickness 0.6 mm and 0.8 mm, the corroded milling CIPs composite had the better absorbing property than the other two samples. The frequency band (RL<-5 dB) could be widened to 8.96-18 GHz at 0.6 mm and 5.92-18 GHz at 0.8 mm, and RL less than -8 dB began to exist in 8.96-14.72 GHz at 0.8 mm.

  8. Effect of Electromagnetic Field on Microstructure and Properties of Bulk AlCrFeNiMo0.2 High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Dong, Yong; Jiang, Li; Tang, Zhongyi; Lu, Yiping; Li, Tingju

    2015-11-01

    The bulk AlCrFeNiMo0.2 high-entropy alloy was successfully prepared by vacuum medium frequency induction melting. The effects of electromagnetic field on microstructure and properties were investigated. The alloy possessed a mixed structure of B2 and BCC, and the phase types were not changed by the electromagnetic field treatment. The microstructure exhibited typical lamellar eutectic cell and rod eutectic cell structures. These eutectic cell structures were constituted by the AlNi-type intermetallic compound and the FeCr-type solid solution. With the increase of electromagnetic field intensity, the hardness increases, while the compressive fracture strength and fracture strain of the alloy first increases and then decreases. The alloy with 15 mT electromagnetic field has the largest fracture strength 2282.3 MPa, yield strength 1160.5 MPa, and fracture strain 0.29. The alloy shows typical ferromagnetic behavior, and the homogenized lamellar eutectic cell microstructure significantly decreased the specific saturation magnetizations.

  9. Evaluation of shear-compressive strength properties for laminated GFRP composites in electromagnet system

    NASA Astrophysics Data System (ADS)

    Song, Jun Hee; Kim, Hak Kun; Kim, Sam Yeon

    2014-07-01

    Laminated fiber-reinforced composites can be applied to an insulating structure of a nuclear fusion device. It is necessary to investigate the interlaminar fracture characteristics of the laminated composites for the assurance of design and structural integrity. The three methods used to prepare the glass fiber reinforced plastic composites tested in this study were vacuum pressure impregnation, high pressure laminate (HPL), and prepreg laminate. We discuss the design criteria for safe application of composites and the shear-compressive test methods for evaluating mechanical properties of the material. Shear-compressive tests could be performed successfully using series-type test jigs that were inclined 0°, 30°, 45°, 60°, and 75° to the normal axis. Shear strength depends strongly on the applied compressive stress. The design range of allowable shear stress was extended by use of the appropriate composite fabrication method. HPL had the largest design range, and the allowable interlaminar shear stress was 0.254 times the compressive stress.

  10. Coaxial line measurement and analysis of electromagnetic properties of soils for sensor applications

    NASA Astrophysics Data System (ADS)

    Folks, William R.; North, Ryan E.; Kelley, Julie R.; Cunningham, Amy L.; McKenna, Jason R.

    2011-06-01

    We report complex permittivity, conductivity, magnetic susceptibility, and attenuation for soils collected from a typical site in a current theater of operations. Our experimental setup consists of three network analyzers along with custombuilt sample holders and data reduction and analysis software. The sample holder has the advantage of large sample volume and a resulting higher signal to noise ratio. This system was developed to determine the electrical properties of soils over a wide frequency range from 100 Hz to 8 GHz. The lower frequencies are applicable to capacitive sensors for small shallow targets, while the higher frequencies are applicable to ground-penetrating radar (GPR) from 50 MHz to 2 GHz and beyond. S-parameter data is collected and reduced using a method, initially developed by Nicolson and Ross (1970)1, for the determination of dielectric permittivity, magnetic permeability, and loss tangent from measured Sparameter data. Experimental results are compared with site geology and mineralogy. Applications include detection of tunnels, land mines, unexploded ordinance (UXO), concrete reinforcements, and other shallow compact targets.

  11. Effect exerted by a radio wave electromagnetic field on the rheological properties of water and portland-cement systems

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Koshevar, V. D.; Shkadretsova, V. G.; Goncharik, S. V.; Chubrik, N. I.; Orlovich, A. I.

    2013-09-01

    We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

  12. Electromagnetic and microwave-absorbing properties of magnetite decorated multiwalled carbon nanotubes prepared with poly(N-vinyl-2-pyrrolidone)

    SciTech Connect

    Zhao, Chunying; Zhang, Aibo; Zheng, Yaping; Luan, Jingfan

    2012-02-15

    Graphical abstract: The Fe{sub 3}O{sub 4}/MWNTs hybrids prepared with PVP achieve a maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs hybrids have better absorption properties in the high-frequency range. Highlight: Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4} decorated MWNTs hybrids were prepared using PVP as dispersant. Black-Right-Pointing-Pointer Many more Fe{sub 3}O{sub 4} particles were attached homogeneously on the surface of MWNTs. Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4}/MWNTs hybrids achieve a maximum reflection loss of -35.8 dB at 8.56 GHz. Black-Right-Pointing-Pointer A new reflection loss peak occurs at the high-frequency of 14.6 GHz. -- Abstract: The magnetite (Fe{sub 3}O{sub 4}) decorated multiwalled carbon nanotubes (MWNTs) hybrids were prepared by an in situ chemical precipitation method using poly(N-vinyl-2-pyrrolidone) (PVP) as dispersant. The structure and morphology of hybrids are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron-microscopy (TEM). The TEM investigation shows that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit less entangled structure and many more Fe{sub 3}O{sub 4} particles are attached homogeneously on the surface of MWNTs, which indicated that PVP can indeed help MWNTs to disperse in isolated form. The electromagnetic and absorbing properties were investigated in a frequency of 2-18 GHz. The results show that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit a superparamagnetic behavior and possess a saturation magnetization of 22.9 emu/g. The maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs

  13. Spectral and dynamic properties of stimulated electromagnetic emission (SEE) generated by very short diagnostic pulses

    NASA Astrophysics Data System (ADS)

    Sergeev, Evgeny; Grach, Savely

    pulse trailing edge increases by 2-3 times, from 0.7 ms to 2 ms, after the mode switching. During the fast decay process the right (HF) flank of the SEE spectrum moves to lower frequencies providing a displacement of the spectral maximum from fd by 15 kHz. Such the SEE decay dynamics can be attributed to the plasma wave energy transfer through the spectrum. Dependencies of diagnostic SEE properties on a shift between the pump wave and diagnostic wave frequencies (which can be easily translated to the altitude displacement), on closeness to the gyroharmonics, on the pump power, and on the time of the day are also discussed. The work was supported by RFBR grants 10-02-00642 and 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia".

  14. Electromagnetic properties and microstructures of in situ MgB2 wires made from three types of boron powders

    NASA Astrophysics Data System (ADS)

    Kodama, Motomune; Kotaki, Hiroshi; Yamamoto, Hiroyuki; Iwane, Tomohiro; Tanaka, Kazuhide; Tanaka, Hideki; Okishiro, Kenji; Okamoto, Kazutaka; Nishijima, Gen; Matsumoto, Akiyoshi; Kumakura, Hiroaki; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Kishio, Kohji

    2016-10-01

    In powder-in-tube processed MgB2 wires, the choice of boron powder as a starting material crucially affects their performance. In this paper, we prepared in situ MgB2 wires from three types of boron powders in various heat-treatment conditions and investigated their electromagnetic properties and microstructures. Their critical current density, J c, varied over a wide range from sample to sample. The difference in J c is understood to be caused by the effect of changes in the electrical connectivity, K, and intrinsic residual resistivity, ρ 0. Here, K represents the effective cross-sectional area for current, and ρ 0 reflects the degree of the charge carrier scattering caused by lattice defects. It was found that the use of boron powder with a large specific surface area leads to a large degree of lattice defects in MgB2 grains and enhances ρ 0, resulting in improving J c. The boron powder produced by thermal decomposition of B2H6 has a large specific surface area. Hence, this boron powder is the most suitable as a starting material for MgB2. Meanwhile, dry pulverization of low-cost boron powder, which is largely produced by active-metal reduction of B2O3, is also effective to increase its specific surface area without introducing impurities, resulting in the enhancement of J c in the entire magnetic field region. This finding broadens the choice of boron powder and contributes to realizing superconducting applications with excellent balance between performance and cost.

  15. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  16. Effects of Electromagnetic Stirring on the Microstructure and High-Temperature Mechanical Properties of a Hyper-eutectic Al-Si-Cu-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Jang, Youngsoo; Choi, Byounghee; Kang, Byungkeun; Hong, Chun Pyo

    2015-02-01

    A liquid treatment method by electromagnetic stirring was applied to a hyper-eutectic Al-15wt pctSi-4wt pctCu-3wt pctNi alloy for the piston manufacturing with diecasting process in order to improve high-temperature mechanical properties of the piston heads. The mechanical properties, such as hardness, high-temperature tensile stress, thermal expansion, and high-temperature relative wear resistance, were estimated using the specimens taken from the liquid-treated diecast products, and the results were compared with those of a conventional metal-mold-cast piston.

  17. Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

    NASA Astrophysics Data System (ADS)

    Paddubskaya, A.; Valynets, N.; Kuzhir, P.; Batrakov, K.; Maksimenko, S.; Kotsilkova, R.; Velichkova, H.; Petrova, I.; Biró, I.; Kertész, K.; Márk, G. I.; Horváth, Z. E.; Biró, L. P.

    2016-04-01

    A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structural characteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic material for electromagnetic compatibility applications in microwave frequency range. Sandwich structures containing only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8-15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.

  18. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  19. Electromagnetic and microwave absorbing properties of SmCo coated single-wall carbon nanotubes/NiZn-ferrite nanocrystalline composite

    NASA Astrophysics Data System (ADS)

    Duan, M. C.; Yu, L. M.; Sheng, L. M.; An, K.; Ren, W.; Zhao, X. L.

    2014-05-01

    The electromagnetism and microwave absorption properties of SmCo coated single-wall carbon nanotubes (SmCo@SWCNTs) and Ni0.5Zn0.5Fe2O4 ferrite (NiZn-ferrite) nanocrystalline composites with different ingredient weight ratios were investigated in the frequency range of 2-18 GHz. SmCo@SWCNTs were prepared by a direct current arc discharge method. NiZn-ferrite nanocrystalline was synthesized by a sol-gel method. The electromagnetic properties of the nanocomposites in the paraffin matrix were measured by a vector network analyzer. The Debye equation and Bruggeman symmetric medium equation were introduced to explain the dielectric properties of the nanocomposites, and the mechanisms for the dielectric and magnetic losses were discussed. The experiment results reveal that the absorbing properties of the nanocomposites could be improved by tuning for a suitable weight ratio between SmCo@SWCNTs and NiZn-ferrite nanocrystallines. The reflection loss simulation calculations demonstrated that the nanocomposite could be excellent materials for microwave absorption.

  20. Full-waveform modeling of Zero-Offset Electromagnetic Induction for Accurate Characterization of Subsurface Electrical Properties

    NASA Astrophysics Data System (ADS)

    Moghadas, D.; André, F.; Vereecken, H.; Lambot, S.

    2009-04-01

    Water is a vital resource for human needs, agriculture, sanitation and industrial supply. The knowledge of soil water dynamics and solute transport is essential in agricultural and environmental engineering as it controls plant growth, hydrological processes, and the contamination of surface and subsurface water. Increased irrigation efficiency has also an important role for water conservation, reducing drainage and mitigating some of the water pollution and soil salinity. Geophysical methods are effective techniques for monitoring the vadose zone. In particular, electromagnetic induction (EMI) can provide in a non-invasive way important information about the soil electrical properties at the field scale, which are mainly correlated to important variables such as soil water content, salinity, and texture. EMI is based on the radiation of a VLF EM wave into the soil. Depending on its electrical conductivity, Foucault currents are generated and produce a secondary EM field which is then recorded by the EMI system. Advanced techniques for EMI data interpretation resort to inverse modeling. Yet, a major gap in current knowledge is the limited accuracy of the forward model used for describing the EMI-subsurface system, usually relying on strongly simplifying assumptions. We present a new low frequency EMI method based on Vector Network Analyzer (VNA) technology and advanced forward modeling using a linear system of complex transfer functions for describing the EMI loop antenna and a three-dimensional solution of Maxwell's equations for wave propagation in multilayered media. VNA permits simple, international standard calibration of the EMI system. We derived a Green's function for the zero-offset, off-ground horizontal loop antenna and also proposed an optimal integration path for faster evaluation of the spatial-domain Green's function from its spectral counterpart. This new integration path shows fewer oscillations compared with the real path and permits to avoid the

  1. Three-dimensional SiO2@Fe3O4 core/shell nanorod array/graphene architecture: synthesis and electromagnetic absorption properties.

    PubMed

    Ren, Yulan; Zhu, Chunling; Zhang, Shen; Li, Chunyan; Chen, Yujin; Gao, Peng; Yang, Piaoping; Ouyang, Qiuyun

    2013-12-21

    We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO2@Fe3O4 core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO2 coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy measurements showed that the SiO2@Fe3O4 core/shell nanorods with a length and diameter of about 60 and 25 nm, respectively, were almost grown perpendicularly on both side surfaces of graphene sheets. The measured electromagnetic parameters showed that the 3D architecture exhibited excellent electromagnetic wave absorption properties, i.e., more than 99% of electromagnetic wave energy could be attenuated by the 3D architecture with an addition amount of only 20 wt% in the paraffin matrix. In addition, the growth mechanism of the 3D architecture was proposed, and thus, the strategy presented here could be used as a typical method to synthesize other 3D magnetic graphene nanostructures for extending their application areas.

  2. Three-dimensional direct numerical simulation of electromagnetically driven multiscale shallow layer flows: Numerical modeling and physical properties

    NASA Astrophysics Data System (ADS)

    Lardeau, Sylvain; Ferrari, Simone; Rossi, Lionel

    2008-12-01

    Three-dimensional (3D) direct numerical simulations of a flow driven by multiscale electromagnetic forcing are performed in order to reproduce with maximum accuracy the quasi-two-dimensional (2D) flow generated by the same multiscale forcing in the laboratory. The method presented is based on a 3D description of the flow and the electromagnetic forcing. Very good agreements between our simulations and the experiments are found both on velocity and acceleration field, this last comparison being, to our knowledge, done for the first time. Such agreement requires that both experiments and simulations are carefully performed and, more importantly, that the underlying simplification to model the experiments and the multiscale electromagnetic forcing do not introduce significant errors. The results presented in this paper differ significantly from previous 2D direct numerical simulation in which a classical linear Rayleigh friction modeling term was used to mimic the effect of the wall-normal friction. Indeed, purely 2D simulations are found to underestimate the Reynolds number and, due to the dominance of nonhomogeneous bottom friction, lead to the wrong physical mechanism. For the range of conditions presented in this paper, the Reynolds number, defined by the ratio between acceleration and viscous terms, remains the order of unity, and the Hartmann number, defined by the ratio between electromagnetic force terms and viscous terms, is about 2. The main conclusion is that 3D simulations are required to model the (3D) electromagnetic forces and the wall-normal shear. Indeed, even if the flow is quasi-2D in terms of energy, a full 3D approach is required to simulate these shallow layer flows driven by multiscale electromagnetic forcing. In the range of forcing intensity investigated in this paper, these multiscale flows remain quasi-2D, with negligible energy in the wall-normal velocity component. It is also shown that the driving terms are the electromagnetic forcing and

  3. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  4. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  5. Dislocation Substructures on the Functional Properties of Niobium for SRF Cavities, focusing on microstructural,microchemical, and electromagnetic characteristic for Florida State University.

    SciTech Connect

    Dhakal, Pashupati

    2016-04-01

    Funding is being requested pursuant to a proposal that was submitted and reviewed through the Portfolio Analysis and Management System (PAMS). PAMS Proposal ID: 222686. Superconducting cavities are the integral part of many energy-efficient particle accelerators around the world. The current material of choice for superconducting cavities is niobium, which is the material with the highest transition temperature among pure metals. The performance of SRF cavities are influenced by the fabrication and processing steps. We plan to study the microstructural, microchemical and electromagnetic properties of Nb that are processed similar to the cavity processing steps to identify and mitigate the limiting factors to improve the performance of SRF cavities.

  6. Improved microwave absorption and electromagnetic properties of BaFe{sub 12}O{sub 19}-poly(vinylidene fluoride) composites by incorporating reduced graphene oxides

    SciTech Connect

    He, Hongcai; Luo, Feifei; Qian, Neng; Wang, Ning

    2015-02-28

    Three-phase composites of poly(vinylidene fluoride)-BaFe{sub 12}O{sub 19}-reduced graphene oxide (PVDF–BFO-RGO) were synthesized by a facile wet chemical method and hot-pressing approach. The phase structure, topography of the hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectra. Influence of RGO on their electromagnetic properties was investigated. Especially, improved microwave absorption and electromagnetic properties of BaFe{sub 12}O{sub 19}–PVDF composites by incorporating RGO were obtained and studied. The PVDF/BFO/RGO sample with m(RGO):m(BFO) = 5:100 shows the best microwave absorption properties with a minimum RL = −32 dB at 11 GHz and with the bandwidth less than −20 dB from 9.6 to 12.8 GHz. The composites were believed to have potential applications as the microwave absorber.

  7. Preparation and electromagnetic properties of Polyaniline(polypyrrole)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Huang, Ying; Wang, Qiufen; He, Qian; Chen, Lin

    2012-10-01

    The nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2 Fe2O4) was prepared by the sol-gel process, and then the polyaniline(PANI)/polypyrrole(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 was produced by in situ polymerization method. The structures, morphology and electromagnetic properties of the samples were characterized by various instruments. XRD, TEM, and FTIR analysis indicated that BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite were homogenously enwrapped by PANI(PPY) coating. The VSM and SDY-4 measurement show that the magnetic properties of the composites decreased with the increase in PANI(PPY) amount, However, the electrical conductivity is on the contrary. The electromagnetic properties of the composites were much better than BaFe12O19/Ni0.8Zn0.2Fe2O4 in the frequency range of 2-15 GHz, which mainly depends on the dielectric loss of PANI(PPY). A minimum reflection loss of the PANI(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposite is -19.7 dB(-21.5 dB) at the frequency of 7.3 GHz (10.7 GHz).

  8. Electromagnetic wave absorption properties of Fe73Si16B7Nb3Cu1-based composites mixed with fine charcoal powder

    NASA Astrophysics Data System (ADS)

    Kim, Sun-I.; Kim, Mi Rae; Sohn, Keun Yong; Park, Won-Wook

    2010-05-01

    Fe73Si16B7Nb3Cu1 soft magnetic powder was crystallized to obtain a nano grain structure and mixed with a fine charcoal powder. The mixtures were tape-cast with polymer-based organic binders to form a sheet-type electromagnetic (EM) wave absorption composite. The EM wave absorption properties of the sheets were investigated using a network analyzer. The results showed that addition of charcoal powder improved the EM-absorbing properties of the composite. The power loss of the EM wave was directly related to the imaginary part of the permeability and permittivity, and it was reviewed in detail. Excellent absorption properties were achieved by adding 5 wt % charcoal powder (-500 mesh) to the Fe-based sheets.

  9. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  10. A new electromagnetic induction sensor using Vector Network Analyzer technology for accurate characterisation of soil electrical properties

    NASA Astrophysics Data System (ADS)

    André, F.; Lambot, S.; Moghadas, D.; Vereecken, H.

    2009-04-01

    Electromagnetic induction (EMI) has been widely used since the 70s to retrieve soil physico-chemical properties through the measurement of soil electrical conductivity. Soil electrical conductivity integrates several factors, mainly soil water content, salinity, clay content and temperature, and to a lesser extent, mineralogy, porosity, structure, cation exchange capacity, organic matter and bulk density. EMI has been shown to be useful for a wide range of environmental applications. EMI is non invasive and individual measurements are almost instantaneous, which permits to characterise large areas with fine spatial and/or temporal resolutions. Nevertheless, current EMI systems present some limitations. First, EMI usually operates at a single or at a limited number of fixed frequencies, which limits the information that can be retrieved from the subsurface. In addition, the calibration of existing commercial sensors is generally rather empirical and not accurate, which reduces the reliability of the data. Finally, the data processing techniques that are used to retrieve the soil electrical properties from EMI data often rely on strong simplifying assumptions with respect to wave propagation through the antenna-air-soil system. Performing EMI measurements with Vector Network Analyzer (VNA) technology would overcome a part of these limitations, allowing to work simultaneously at a wide range of frequencies and to readily perform robust calibrations, which are defined as an international standard. On that basis, we have developed a new algorithm for off-ground, zero-offset, frequency domain EMI based on full-waveform inverse modelling. The EMI forward model is based on a linear system of complex transfer functions for describing the loop antenna and its interactions with soil and an exact solution of Maxwell's equations for wave propagation in three-dimensional multilayered media. The approach has been validated in laboratory conditions for measurements at different

  11. Electromagnetic Showers at High Energy

    ERIC Educational Resources Information Center

    Loos, J. S.; Dawson, S. L.

    1978-01-01

    Some of the properties of electromagnetic showers observed in an experimental study are illustrated. Experimental data and results from quantum electrodynamics are discussed. Data and theory are compared using computer simulation. (BB)

  12. Polarization distribution control of anisotropic electromagnetic Gaussian-Schell model beams on free propagation by exploiting correlation properties at the source plane.

    PubMed

    Zhang, Rong; Wang, Xiangzhao; Cheng, Xin; Qiu, Zicheng

    2010-11-01

    When propagating in free space, the transversal distribution of the degree of polarization of an anisotropic electromagnetic Gaussian-Schell model (AEGSM) beam will generally undergo a complex evolution process. We find that this transversal distribution of the degree of polarization of an AEGSM beam can be controlled by exploiting the partial correlation properties of the source. The main research of our paper falls into two parts. First, the concept of analogical propagation of the transversal distribution of the degree of polarization is proposed, and the condition for an AEGSM beam having an analogical propagation is obtained. When an AEGSM beam is on analogical propagation, the distribution of the degree of polarization on any cross section of the beam is always similar to that on the source plane, except that the size of the distribution pattern will expand continuously as the propagation distance increases. Second, the far-field transversal distribution of the degree of polarization is considered, and the condition for the far-field transversal polarization distribution of an AEGSM beam to be always of circularly symmetric shape, no matter how complicated it is on the source, is obtained. Our research is expected to find applications in areas that make use of the polarization properties of random electromagnetic beams.

  13. Effects of TiO2 and Co2O3 combination additions on the elemental distribution and electromagnetic properties of Mn-Zn power ferrites

    NASA Astrophysics Data System (ADS)

    Yang, W. D.; Wang, Y. G.

    2015-06-01

    The effects of TiO2 and Co2O3 combination additions on the elemental distribution and electromagnetic properties of Mn-Zn power ferrites are investigated. TiO2 addition can promote Co2O3 transfer from grain boundaries to the bulk of the grains. The temperature at which the highest initial permeability μi and the lowest power losses PL appear shifts to low temperature range with the increase of Co2O3 content. Compared with the reference sample without TiO2 and Co2O3 addition, the microstructure and electromagnetic properties of Mn-Zn power ferrites can be considerably improved with suitable amounts of TiO2 and Co2O3 combination additions. At the peak temperature, the sample with the 0.1 wt% TiO2 and 0.08 wt% Co2O3 additions has an increase of 15.8% in μi to 3951, and a decrease of 22.9% in PL to 286 kW/m3. The saturation magnetic induction Bs and electrical resistivity ρ at 25 °C reach the highest values of 532 mT and 8.12 Ω m, respectively.

  14. Electromagnetic characterization of nonevaporable getter properties between 220-330 and 500-750 GHz for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Koukovini-Platia, E.; Rumolo, G.; Zannini, C.

    2017-01-01

    Due to its effective pumping ability, nonevaporable getter (NEG) coating is considered for the vacuum chambers of the Compact Linear Collider (CLIC) electron damping rings (EDR). The aim is to suppress fast beam ion instabilities. The electromagnetic (EM) characterization of the NEG properties up to ultra-high frequencies is required for the correct impedance modeling of the damping ring (DR) components. The properties are determined using rectangular waveguides which are coated with NEG. The method is based on a combination of complex transmission coefficient S21 measurements with a vector network analyzer (VNA) and 3D simulations using CST Microwave Studio® (CST MWS). The frequency ranges discussed in this paper are 220-330 and 500-750 GHz.

  15. Synthesis and physicochemical properties of composites for electromagnetic shielding applications: a polymeric matrix impregnated with iron- or cobalt-containing nanoparticles

    NASA Astrophysics Data System (ADS)

    Yurkov, Gleb Yurjevich; Fionov, Alexander Sergeevich; Kozinkin, Aleksander Vladimirovich; Koksharov, Yury Alekseevich; Ovtchenkov, Yevgeniy Anatolievich; Pankratov, Denis Alexandrovich; Popkov, Oleg Vladimirovich; Vlasenko, Valery Grigorievich; Kozinkin, Yuriy Aleksandrovich; Biryukova, Marina Igorevna; Kolesov, Vladimir Vladimirovich; Kondrashov, Stanislav Vladimirovich; Taratanov, Nikolai Alexandrovich; Bouznik, Viacheslav Mikhailovich

    2012-01-01

    Magnetic, magnetic resonance, and structural properties of iron and cobalt nanoparticles embedded in a polyethylene matrix were studied. The materials were prepared by thermal decomposition of cobalt or iron formate in a polyethylene melt in mineral oil and contained from 2 to 40% wt. of metal. Transmission electron microscopy data indicate that the average diameter of particles is up to 8.0 nm. According to extended x-ray absorption fine structure and Mössbauer spectroscopy studies, the particles comprise a metallic core and nonmetallic shell which is chemically bound to the surrounding matrix. Electrophysical and magnetic properties of the materials prepared were studied along with their reflection and attenuation factors in the super high frequency band. The materials were found to be suitable for use in electromagnetic shielding.

  16. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Effect of polyacrylamide on morphology and electromagnetic properties of chrysanthemum-like ZnO particles

    NASA Astrophysics Data System (ADS)

    Yan, Jun-Feng; Zhang, Zhi-Yong; You, Tian-Gui; Zhao, Wu; Yun, Jiang-Ni; Zhang, Fu-Chun

    2009-10-01

    Through hydrothermal process, the chrysanthemum-like ZnO particles are prepared with zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and sodium hydroxide (NaOH) used as main resources under the different concentrations of surfactant polyacrylamide (PAM). The microstructure, morphology and the electromagnetic properties of the as-prepared products are characterized by high-resolution transmissïon electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM) and microwave vector network analyzer, respectively. The experimental results indicate that the as-prepared products are ZnO single crystalline with hexagona wurtzite structure, that the values of slenderness ratio Ld are different in different PAM concentrations, and that the good magnetic loss property is found in the ZnO products, and the average magnetic loss tangent tan δu increases with PAM concentration increasing, while the dielectric loss tangent tan δe decreases.

  17. PREFACE: MEM11: The 6th International Workshop on Mechanical-Electromagnetic Properties of Composite Superconductors (Okinawa, Japan, 5-7 December 2011) MEM11: The 6th International Workshop on Mechanical-Electromagnetic Properties of Composite Superconductors (Okinawa, Japan, 5-7 December 2011)

    NASA Astrophysics Data System (ADS)

    Awaji, Satoshi; Osamura, Kozo; Hampshire, Damian

    2012-05-01

    The effect of stress and strain on the electromagnetic properties of superconducting composite conductors is one of the key issues for the practical application of superconductivity. To discuss these subjects thoroughly, the International Workshop on Mechanical-Electromagnetic Properties of Composite Superconductors (MEM) has been held regularly since 2001. The 6th workshop (MEM11) was held in Okinawa, Japan in 2011, which was the centennial of the discovery of superconductivity by Professor Kamerlingh Onnes, as well as the 25th anniversary of the discovery of high temperature superconductors (HTS). Although it was originally planned that MEM11 be held in Mito, the workshop venue was changed because of the serious disaster in the north of Japan on 11 March 2011. Sixty five scientists participated in this specialized workshop. Fifty six papers were presented in the following six sessions: (1) Intrinsic strain effects on low temperature superconductors (LTS) and HTS, (2) The International Thermonuclear Experimental Reactor (ITER), (3) Strain evaluation by quantum beams, (4) Flux pinning properties of HTS, (5) Standardization and the Versailles Project on Advanced Materials and Standards (VAMAS) and (6) High field magnets. Several large topics were presented and discussed at the workshop: the important progress in methods for non-invasive measurements of the local strain exerted on the superconducting components in superconducting wires and cables using quantum beam techniques. This approach provides powerful tools for investigating the effect of strain in composite superconductors; the intrinsic strain effects in LTS and HTS in the reversible strain region. Recently, it has become easier to determine quantitatively the strain dependence of critical current when the local strain is measured directly, and the mechanical and electromagnetic properties of the superconductors used in the ITER tokamak. This was a major topic at the workshop since the superconducting

  18. Electromagnetic Field Effects in Explosives

    NASA Astrophysics Data System (ADS)

    Tasker, D. G.; Whitley, V. H.; Lee, R. J.

    2009-12-01

    Present and previous research on the effects of electromagnetic fields on the initiation and detonation of explosives and the electromagnetic properties of explosives are reviewed. Among the topics related to detonating explosives are: enhancement of performance; and control of initiation and growth of reaction. Two series of experiments were performed to determine the effects of 1-T magnetic fields on explosive initiation and growth in the modified gap test and on the propagation of explosively generated plasma into air. The results have implications for the control of reactions in explosives and for the use of electromagnetic particle velocity gauges.

  19. Electromagnetic acoustic imaging.

    PubMed

    Emerson, Jane F; Chang, David B; McNaughton, Stuart; Jeong, Jong Seob; Shung, K K; Cerwin, Stephen A

    2013-02-01

    Electromagnetic acoustic imaging (EMAI) is a new imaging technique that uses long-wavelength RF electromagnetic (EM) waves to induce ultrasound emission. Signal intensity and image contrast have been found to depend on spatially varying electrical conductivity of the medium in addition to conventional acoustic properties. The resultant conductivity- weighted ultrasound data may enhance the diagnostic performance of medical ultrasound in cancer and cardiovascular applications because of the known changes in conductivity of malignancy and blood-filled spaces. EMAI has a potential advantage over other related imaging techniques because it combines the high resolution associated with ultrasound detection with the generation of the ultrasound signals directly related to physiologically important electrical properties of the tissues. Here, we report the theoretical development of EMAI, implementation of a dual-mode EMAI/ultrasound apparatus, and successful demonstrations of EMAI in various phantoms designed to establish feasibility of the approach for eventual medical applications.

  20. High-pressure crystal growth and electromagnetic properties of 5d double-perovskite Ca₃OsO₆

    SciTech Connect

    Feng, Hai Luke; Shi, Youguo; Guo, Yanfeng; Li, Jun; Sato, Akira; Sun, Ying; Wang, Xia; Yu, Shan; Sathish, Clastin I.; Yamaura, Kazunari

    2013-05-01

    Single crystals of the osmium-containing compound Ca₃OsO₆ have been successfully grown under high-pressure conditions, for the first time. The crystal structure of Ca₃OsO₆ atoms being fully ordered at the perovskite B-site. The electromagnetic analysis shows that the crystal exhibits a semiconductor-like behavior below 300 K and undergoes an antiferromagnetic transition at 50 K. - Graphical Abstract: Schematic image of crystal structure of Ca₃OsO₆ as determined by X-ray diffraction, where the gray and black octahedrons are occupied by Ca and Os, respectively. Top inset reveals an optic image of a typical Ca₃OsO₆ single crystal. Highlights: • Single crystals of Ca₃OsO₆ have been successfully grown under high-pressure. • Ca₃OsO₆ crystalizes into an ordered double-perovskite structure. • The Ca₃OsO₆ undergoes an antiferromagnetic transition at 50 K.

  1. Low intensity electromagnetic irradiation with 70.6 and 73 GHz frequencies affects Escherichia coli growth and changes water properties.

    PubMed

    Torgomyan, Heghine; Kalantaryan, Vitaly; Trchounian, Armen

    2011-07-01

    The low intensity electromagnetic irradiation (EMI) of the 70.6 and 73 GHz frequency is resonant for Escherichia coli but not for water. In this study, E. coli irradiation with this EMI during 1 h directly and in bi-distilled water or in the assay buffer with those frequencies resulted with noticeable changes in bacterial growth parameters. Furthermore, after EMI, 2 h rest of bacteria renewed their growth in 1.2-fold, but repeated EMI--had no significant action. Moreover, water absorbance, pH, and electric conductance were changed markedly after such irradiation. The results point out that EMI of the 70.6 and 73 GHz frequency can interact with bacteria affecting growth and in the same time with the surrounding medium (water) as well.

  2. Synthesis and electromagnetic properties of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites

    SciTech Connect

    Xie, Yu; Hong, Xiaowei; Liu, Jinmei; Le, Zhanggao; Huang, Feihui; Qin, Yuancheng; Zhong, Rong; Gao, Yunhua; Pan, Jianfei; Ling, Yun

    2014-02-01

    Graphical abstract: Due to combining different functions and characteristics of individual materials, hybrid nanocomposite materials can strengthen their applications. Magnetic-conductive nanocomposites are the promising materials with electromagnetic loss, which have synergetic behavior between magnetic and conductive materials. It is the first time to report the synthesis of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide (BF/TD) composites by the gel-precursor self-propagating combustion process. The influence of mass ratio of BF and TD on the electromagnetic properties of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites was studied. The tgδ{sub μ} and tgδ{sub ε} of BF–TD composites. - Highlights: • It is the first time to report BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites. • The composites are prepared by the gel-precursor self-propagating combustion. • The electromagnetic properties could be adjusted by the mass ratio of BF and TD. • The introduction of TD enhances the dielectric loss and widens the frequency bands. • BF/TD composites will be microwave absorption materials with wide frequency band. - Abstract: Doped BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites have been prepared by the gel-precursor self-propagating combustion process. The characterization of the composites are performed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Differential thermal analysis-thermo gravimetry (DTA–TG), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and network analyzer. Both XRD and FT-IR indicate that the doped BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites are successfully synthesized and there are some interactions between BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19} and titanium dioxide. DTA–TG analysis of BaFe{sub 11.92}(LaNd){sub 0.04}O{sub 19}/titanium dioxide composites shows that the composite gel

  3. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a

  4. Characterization and high resolution mapping of soil hydrogeophysical properties from ground penetrating radar and electromagnetic induction data in a vineyard in southern France

    NASA Astrophysics Data System (ADS)

    Andre, F.; van Durmen, R.; Saussez, S.; van Leeuwen, C.; Moghadas, D.; Delvaux, B.; Vereecken, H.; Sebastien, L.

    2010-12-01

    Soil and climate are acknowledged to greatly affect vine growth and grape berry composition through their strong influence on vine water status. Over a limited area, climatic factors may be considered as rather homogeneous for a given vintage while soil characteristics may vary strongly over short distances. Therefore, detailed characterization of soil hydrogeophysical properties is of prime importance for the definition of optimal vineyard practices. In that respect, ground penetrating radar (GPR) and electromagnetic induction (EMI) are effective geophysical techniques for fast and non-invasive determination of shallow subsurface properties through the measurement of soil dielectric permittivity and electrical conductivity. Given contrasted sensitivities of GPR and EMI to soil electrical properties, combining measurements from both techniques allows to merge complementary information, thereby leading to more accurate quantitative characterisation of soil. Classical GPR and EMI data processing techniques for soil properties characterisation rely on strongly simplifying assumptions in the modelling of electromagnetic phenomena, leading to significant errors on the estimates and accounting for only a part of the data information content. We developed generalized multi-offset full-waveform approaches for modelling off-ground and on-ground GPR and EMI signals. GPR and EMI systems are modelled using sets of infinitesimal electric and magnetic dipoles, allowing us to properly describe the distribution of the scattered field when the subsurface is located in the near-field of the antenna. The antenna model is coupled with a three-dimensional Green’s function, corresponding to a specific solution of the Maxwell’s equations for wave propagation or diffusion in multilayered media. The approaches were applied in a vineyard in south of France (Saint-Emilion) over a 30-ha area characterized by strong spatial variations of soil types. Around 1 million GPR waveforms and 73

  5. Electromagnetic interference shielding in 1-18 GHz frequency and electrical property correlations in poly(vinylidene fluoride)-multi-walled carbon nanotube composites.

    PubMed

    Kumar, G Sudheer; Vishnupriya, D; Joshi, Anupama; Datar, Suwarna; Patro, T Umasankar

    2015-08-21

    Electromagnetic interference (EMI) shielding properties in the 1-18 GHz frequency range for multi-walled carbon nanotube (MWNT)-poly(vinylidene fluoride) (PVDF) composites are reported. A simple and gentle acid-treatment of MWNT showed a percolation threshold (PT) of 0.15 wt% in the PVDF matrix as against 0.35 wt% for unfunctionalized MWNT. Acid-treatment of MWNT significantly improves dispersion, interfacial adhesion with the matrix and the EMI shielding properties of PVDF composites. Further, the EMI shielding properties are correlated with the electrical properties. Using composite films of 0.3 mm thickness, the maximum shielding effectiveness (SET) values for 4 wt% unfunctionalized MWNT composites are found to be about 110, 45, 30, 26, and 58 dB for L (1-2 GHz), S (2-4 GHz), C (4-5.8 GHz), J (5.8-8 GHz), and X (8-12 GHz) bands, while the corresponding values for only 0.5 wt% acid functionalized MWNT composites are about 98, 45, 26, 19, and 47 dB, respectively. The electrical conductivity for both the cases is ∼10(-3) S cm(-1) and the weight contents of CNTs are higher than the PT for the respective composites. The comparable EMI SE and electrical conductivity values for both the composites at different weight fractions of CNTs suggest that there is a critical electrical conductivity above which the composites attain improved EMI shielding properties. Further, the shielding mechanism was found to be dominated by absorption loss. Therefore, the composites may also serve as a radar absorbing material.

  6. Electromagnetic Spectroscopy of Normal Breast Tissue Specimens Obtained From Reduction Surgeries: Comparison of Optical and Microwave Properties

    PubMed Central

    Lazebnik, Mariya; Zhu, Changfang; Palmer, Gregory M.; Harter, Josephine; Sewall, Sarah; Ramanujam, Nirmala; Hagness, Susan C.

    2009-01-01

    Techniques utilizing electromagnetic energy at microwave and optical frequencies have been shown to be promising for breast cancer detection and diagnosis. Since different biophysical mechanisms are exploited at these frequencies to discriminate between healthy and diseased tissue, combining these two modalities may result in a more powerful approach for breast cancer detection and diagnosis. Toward this end, we performed microwave dielectric spectroscopy and optical diffuse reflectance spectroscopy measurements at the same sites on freshly-excised normal breast tissues obtained from reduction surgeries at the University of Wisconsin Hospital, using microwave and optical probes with very similar sensing volumes. We found that the microwave dielectric constant and effective conductivity are correlated with tissue composition across the entire measurement frequency range (|r|~0.5–0.6, p<0.01), and that the optical absorption coefficient at 460 nm and optical scattering coefficient are correlated with tissue composition (|r|~ 0.4–0.6, p<0.02). Finally, we found that the optical absorption coefficient at 460 nm is correlated with the microwave dielectric constant and effective conductivity (r=−0.55, p<0.01). Our results suggest that combining optical and microwave modalities for analyzing breast tissue samples may serve as a crosscheck and provide complementary information about tissue composition. PMID:18838370

  7. Electromagnetic levitation applications

    SciTech Connect

    Bayazitoglu, Y.

    1996-11-01

    At high temperatures, most materials react with the walls of their containers. This inevitably leads to material contamination and property degradation. Therefore, it becomes difficult to process materials to the required degree of purity and/or measure their properties at high temperatures. Levitation melting has been used on earth and microgravity since to circumvent this problem. In this paper, first a broad survey of the work done in electromagnetic levitation since its invention is given. Then the heat generation due to an alternating magnetic field is studied. Finally, the application of levitation melting in the determination of thermal diffusivity, emissivity, surface tension and viscosity of liquid metals is presented.

  8. Effects of 3 Hz and 60 Hz Extremely Low Frequency Electromagnetic Fields on Anxiety-Like Behaviors, Memory Retention of Passive Avoidance and Electrophysiological Properties of Male Rats

    PubMed Central

    Rostami, Amin; Shahani, Minoo; Zarrindast, Mohammad Reza; Semnanian, Saeed; Rahmati Roudsari, Mohammad; Rezaei Tavirani, Mostafa; Hasanzadeh, Hadi

    2016-01-01

    Introduction: The effects of electromagnetic fields on biological organisms have been a controversial and also interesting debate over the past few decades, despite the wide range of investigations, many aspects of extremely low frequency electromagnetic fields (ELF/EMFs) effects including mechanism of their interaction with live organisms and also their possible biological applications still remain ambiguous. In the present study, we investigated whether the exposures of ELF/EMF with frequencies of 3 Hz and 60 Hz can affect the memory, anxiety like behaviors, electrophysiological properties and brain’s proteome in rats. Methods: Male rats were exposed to 3 Hz and 60 Hz ELF/EMFs in a protocol consisting of 2 cycles of 2 h/day exposure for 4 days separated with a 2-day interval. Short term memory and anxiety like behaviors were assessed immediately, 1 and 2 weeks after the exposures. Effects of short term exposure were also assessed using electrophysiological approach immediately after 2 hours exposure. Results: Behavioral test revealed that immediately after the end of exposures, locomotor activity of both 3 Hz and 60 Hz exposed groups significantly decreased compared to sham group. This exposure protocol had no effect on anxiety like behavior during the 2 weeks after the treatment and also on short term memory. A significant reduction in firing rate of locus coeruleus (LC) was found after 2 hours of both 3 Hz and 60 Hz exposures. Proteome analysis also revealed global changes in whole brain proteome after treatment. Conclusion: Here, some evidence regarding the fact that such exposures can alter locomotor activity and neurons firing rate in male rats were presented. PMID:27330708

  9. DIRECT CURRENT ELECTROMAGNETIC PUMP

    DOEpatents

    Barnes, A.H.

    1957-11-01

    An improved d-c electromagnetic pump is presented in which the poles, and consequently the magetic gap at the poles, are tapered to be wider at the upstream end. In addition, the cross section of the tube carryiQ the liquid metal is tapered so that the velocity of the pumped liquid increases in the downstream direction at a rate such that the counter-induced voltage in the liquid metal remains constant as it traverses the region between the poles. This configuration compensates for the distortion of the magnetic field caused by the induced voltage that would otherwise result in the lowering of the pumping capacity. This improved electromagnetic pump as practical application in the pumping of liquid metal coolants for nuclear reactors where conventional positive displacement pumps have proved unsatisfactory due to the high temperatures and the corrosive properties of the liquid metals involved.

  10. Electromagnetic wave in a relativistic magnetized plasma

    SciTech Connect

    Krasovitskiy, V. B.

    2009-12-15

    Results are presented from a theoretical investigation of the dispersion properties of a relativistic plasma in which an electromagnetic wave propagates along an external magnetic field. The dielectric tensor in integral form is simplified by separating its imaginary and real parts. A dispersion relation for an electromagnetic wave is obtained that makes it possible to analyze the dispersion and collisionless damping of electromagnetic perturbations over a broad parameter range for both nonrelativistic and ultrarelativistic plasmas.

  11. Electromagnetic and microwave absorbing properties of the composites containing flaky FeSiAl powders mixed with MnO2 in 1-18 GHz

    NASA Astrophysics Data System (ADS)

    Xu, Haibing; Bie, Shaowei; Jiang, Jianjun; Yuan, Wei; Chen, Qian; Xu, Yongshun

    2016-03-01

    The flaky FeSiAl/ irregular shaped MnO2 composite with the different mass ratios were prepared by using a two-roll mixer and a vulcanizing machine. The morphologies of the composite absorbers were characterized by a scanning electron microscope. The microwave electromagnetic properties of the composites were measured using a vector network analyzer in the range of 1-18 GHz. The effect of the mass ratio of FeSiAl/MnO2 on the microwave loss properties of the composites was investigated. The results show that the reflection loss (RL) values exceeding -20 dB from 3.5 to 16.5 GHz can be obtained for the flaky FeSiAl/MnO2 mass ratio of 1:1 from 1.5 mm to 5 mm. In addition, the FeSiAl/MnO2 composite with the FeSiAl/MnO2 mass ratio of 7:3 has -10 dB bandwidth of 6.6 GHz (from 11.4-18 GHz) with a thickness of 1.5 mm. It is found that the flaky FeSiAl/MnO2 composites can be potential microwave absorption materials.

  12. Simultaneous enhancement in mechanical strength, electrical conductivity, and electromagnetic shielding properties in PVDF-ABS blends containing PMMA wrapped multiwall carbon nanotubes.

    PubMed

    Kar, Goutam Prasanna; Biswas, Sourav; Bose, Suryasarathi

    2015-06-14

    A unique approach was adopted to drive the multiwall carbon nanotubes (MWNTs) to the interface of immiscible PVDF-ABS blends by wrapping the nanotubes with a mutually miscible homopolymer (PMMA). A tailor made interface with an improved stress transfer was achieved in the blends with PMMA wrapped MWNTs. This manifested in an impressive 108% increment in the tensile strength and 48% increment in the Young's modulus with 3 wt% PMMA wrapped MWNTs in striking contrast to the neat blends. As the PMMA wrapped MWNTs localized at the interface of PVDF-ABS blends, the electrical conductivity could be tuned with respect to only MWNTs, which were selectively localized in the PVDF phase, driven by thermodynamics. The electromagnetic shielding properties were assessed using a vector network analyser in a broad range of frequency, X-band (8-12 GHz) and Ku-band (12-18 GHz). Interestingly, enhanced EM shielding was achieved by this unique approach. The blends with only MWNTs shielded the EM waves mostly by reflection however, the blends with PMMA wrapped MWNTs (3 wt%) shielded mostly by absorption (62%). This study opens new avenues in designing materials, which show simultaneous improvement in mechanical, electrical conductivity and EM shielding properties.

  13. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  14. Electromagnetic Induction Rediscovered Using Original Texts.

    ERIC Educational Resources Information Center

    Barth, Michael

    2000-01-01

    Describes a teaching unit on electromagnetic induction using historic texts. Uses some of Faraday's diary entries from 1831 to introduce the phenomenon of electromagnetic induction and teach about the properties of electricity, of taking conclusions from experiment, and scientific methodology. (ASK)

  15. Electromagnetic Characterization Of Metallic Sensory Alloy

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Simpson, John; Wallace, Terryl A.; Newman, John A.; Leser, Paul; Lahue, Rob

    2012-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  16. Lanthanum and Neodymium Doped Barium Ferrite-TiO₂/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties.

    PubMed

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-02-09

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0-18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of -21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail.

  17. Lanthanum and Neodymium Doped Barium Ferrite-TiO2/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties

    PubMed Central

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-01-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0–18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of −21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail. PMID:26857939

  18. International comparison of the properties of NdFeB permanent magnets measured using an electromagnet and a pulsed field magnetometer

    NASA Astrophysics Data System (ADS)

    Hall, Michael

    2013-08-01

    An IEC TC 68 comparison on the measurement of the magnetic properties of permanent magnets was completed in 2011. Measurements were performed on 6 NdFeB magnets with intrinsic coercivities ranging from 1000 to 2600 kA/m by 8 institutes based in China, Japan, Italy, Belgium, Germany and the UK. Many versions of a Pulsed Field Magnetometer (PFM) that can determine the full BH curve in as little as 100 ms have been developed during the last 2 decades. By comparing measurements made using an internationally accepted electromagnet method and pulsed methods, the influence of the dynamic effects of the latter could be investigated and established. For the quantities remanence, B r , magnetic flux density coercivity, H cB and energy product, BH max the measurements agree within the combined uncertainties. For the intrinsic coercivity, H cJ , the dependence of the measurement of this quantity on the speed at which the magnetic field is reversed was found to be significant with the largest changes in value occurring as a DC measurement condition is approached.

  19. Preparation of nanocrystalline-coated carbon nanotube/Ni0.5Zn0.5Fe2O4 composite with excellent electromagnetic property as microwave absorber

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao-Bing; Shen, Lu; Li, Lei; Huang, Tong-Ming; Hu, Chun-Feng; Pan, Wei-Ming; Jin, Xi-Hai; Sun, Jing; Gao, Lian; Huang, Qing

    2013-04-01

    A combined precipitation-hydrothermal method was used to fabricate carbon nanotube/Ni0.5Zn0.5Fe2O4 ferrite composite powders. The phase, microstructure and electromagnetic properties of CNT/Ni0.5Zn0.5Fe2O4 composites were investigated. After surface modification, The zeta potential value of CNTs could maintain at about -50 mV when pH is higher than 8, which affords a suitable surface environment for in situ coating of Ni0.5Zn0.5Fe2O4 nanocrystallines. With increasing CNTs content, the saturation magnetization of the composites is gradually reduced, while the complex magnetic permeability changes little. The complex dielectric constant of the composites is significantly increased when the concentration of CNTs approaches the percolation threshold value of 2 wt%. When CNTs content is 5 wt%, the reflection ratios are less than -10 dB within the frequency range 2-9 GHz, and the reflection ratios reach a minimum -32.5 dB at a frequency of about 3.9 GHz.

  20. Lanthanum and Neodymium Doped Barium Ferrite-TiO2/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-02-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0-18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of -21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail.

  1. Studies on the microwave permittivity and electromagnetic wave absorption properties of Fe-based nano-composite flakes in different sizes

    NASA Astrophysics Data System (ADS)

    Wu, Yanhui; Han, Mangui; Liu, Tao; Deng, Longjiang

    2015-07-01

    The effective permittivity of composites containing Fe-Cu-Nb-Si-B nanocrystalline micro flakes has been studied within 0.5-10 GHz. Obvious differences in microwave permittivity have been observed for composites consisting of large flakes (size range: 23-111 μm, average thickness: 4.5 μm) and small flakes (size range: 3-21 μm, average thickness: 1.3 μm). Both the real part and imaginary part of permittivity of large flake composite are much larger than these small one in a given frequency. And faster decrease of permittivity with the increasing frequency can be observed for large flake composite than that of small one. These differences in permittivity spectra of different flakes have been explained from the perspective of interfacial polarization and ac conductivity. The assumption that more extensive ohmic contact interface between large flakes and matrix has been validated by the fittings and the calculated percolation threshold. Meanwhile, the permeability spectra of both composites also have been studied by Lorentzian dispersion law. The broadened spectra can be attributed to the distribution of magnetic anisotropy fields of two kinds of ferromagnetic phases in the particles. Finally, the composite containing the small flakes exhibits better electromagnetic wave absorption properties.

  2. Fabrication and electromagnetic properties of bio-based helical soft-core particles by way of Ni-Fe alloy electroplating

    NASA Astrophysics Data System (ADS)

    Lan, Mingming; Zhang, Deyuan; Cai, Jun; Zhang, Wenqiang; Yuan, Liming

    2011-12-01

    Ni-Fe alloy electroplating was used as a bio-limited forming process to fabricate bio-based helical soft-core ferromagnetic particles, and a low frequency vibration device was applied to the cathode to avoid microorganism (Spirulina platens) cells adhesion to the copper net during the course of plating. The morphologies and ingredients of the coated Spirulina cells were characterized using scanning electron microscopy and energy dispersive spectrometer. The complex permittivity and permeability of the samples containing the coated Spirulina cells before and after heat treatment were measured and investigated by a vector network analyzer. The results show that the Spirulina cells after plating keep their initial helical shape, and applying low frequency vibration to the copper net cathode in the plating process can effectively prevent agglomeration and intertwinement of the Spirulina cells. The microwave absorbing and electromagnetic properties of the samples containing the coated Spirulina cells particles with heat treatment are superior to those samples containing the coated Spirulina cells particles without heat treatment.

  3. PSynthesis, characterization and electromagnetic properties of Zn-substituted CoFe2O4 via sucrose assisted combustion route

    NASA Astrophysics Data System (ADS)

    Gabal, M. A.; Al-Juaid, A. A.; Al-Rashed, S. M.; Hussein, M. A.; Al-Marzouki, F.

    2017-03-01

    Nanocrystalline Co1-xZnxFe2O4 ferrites (0.0≤x≤0.1) were synthesized via simple, economic and environmentally friend sucrose auto-combustion method. An appropriate mechanism for complexation process as well as ferrites formation was suggested and discussed. The detailed structural studies were estimated through X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) measurements. The results confirmed the formation of mixed spinel phase with cubic structure and exhibited a gradual decrease in the crystal size from 58 nm to 20 nm by the addition of zinc. Based on the obtained structural parameters, an appropriate cation distribution was suggested and reinforced via electrical and magnetic properties measurements. Hysteresis loops measurements, indicated ferromagnetic characteristics, with hard magnetic properties, for the samples with 0.0≤x≤0.6. The samples with higher Zn-content exhibited paramagnetic properties. The changes in the magnetization and coercivity by the addition of zinc can be discussed in the view of the influence of cationic stoichiometry and magneto-crystalline anisotropy, respectively. The huge decrease in the magnetization value at x≥0.8 suggested a shift from ferromagnetic to paramagnetic characteristics. Ac-conductivity as well as dielectric constant behaviors reinforced this magnetic transition. The obtained Curie transition temperatures (TC) were gradually shifted to lower temperatures by the addition of zinc. The addition of zinc results in the substitution of Co2+ ions in the octahedral sites thus, decreases B-B hopping probability, decreases conductivity and consequently increases activation energy. The most predominant conduction mechanisms in the ferromagnetic and paramagnetic regions are expected to be due to electron hoppings between different valence state ions and small positive polaron migration, respectively.

  4. Electromagnetic Radiation System (EMRS) for Susceptibility Testing.

    DTIC Science & Technology

    ELECTROMAGNETIC COMPATIBILITY, *ELECTROMAGNETIC SUSCEPTIBILITY, COMMUNICATION EQUIPMENT, ELECTRONIC EQUIPMENT, ELECTROMAGNETIC RADIATION , ANTENNAS, ELECTROMAGNETIC INTERFERENCE, RADAR SIGNALS, RADIO SIGNALS, FIELD INTENSITY.

  5. Structural, electro-magnetic, and optical properties of Ba(Fe,Ni)2As2 single-crystal thin film

    NASA Astrophysics Data System (ADS)

    Yoon, Sejun; Seo, Yu-Seong; Lee, Seokbae; Weiss, Jeremy D.; Jiang, Jianyi; Oh, MyeongJun; Lee, Jongmin; Seo, Sehun; Jo, Youn Jung; Hellstrom, Eric E.; Hwang, Jungseek; Lee, Sanghan

    2017-03-01

    We investigated the superconducting transition temperature (T c), critical current density (J c) and optical properties of optimally doped Ba(Fe0.95Ni0.05)2As2 (Ni-Ba122) single-crystalline epitaxial thin films grown by pulsed laser deposition for the first time. The T c at zero resistivity was about 20.5 K and the J c at self-field and 4.2 K was 2.8 MA cm-2 calculated by the Bean model. The superconducting properties such as T c and J c of thin films are comparable to those of bulk single-crystal samples. The superfluid plasma frequency (λ p,S) of Ni-Ba122 thin film is ˜7033 cm-1 obtained by optical spectroscopic technique. Based on this plasma frequency, we obtained the London penetration depth (λ L), ˜226 nm at 8 K, which is comparable to those of optimally Co- and K-doped BaFe2As2 single crystals.

  6. Effect of co substitution of Mg and Zn on electromagnetic properties of NiCuZn ferrites

    NASA Astrophysics Data System (ADS)

    Sujatha, Ch.; Reddy, K. Venugopal; Babu, K. Sowri; Reddy, A. Rama Chandra; Suresh, M. Buchi; Rao, K. H.

    2013-07-01

    Ni0.5-2xMgxCu0.05Zn0.45+xFe2O4 (x=0, 0.04, 0.08, 0.12, and 0.16) ferrite samples were prepared through sol-gel method using polyvinyl alcohol as a chelating agent. Structural, magnetic, dielectric and electrical properties of the sintered samples were investigated using the characterisation techniques such as X-ray Diffractometer, Vibration sample magnetometer and impedance analyser respectively. X-ray diffraction patterns confirmed the formation of single phase cubic spinel structure of the samples. FTIR spectra showed two prominent bands (400 cm-1 and 600 cm-1) corresponding to characteristic of ferrites. Substitution of Mg and Zn for Ni showed gradual decrease of both magnetisation and coercivity. Magnetic permeability showed increasing trend with composition due to low anisotropy constant of Mg and Zn compared to Ni. Dielectric properties of the samples showed that both the dielectric constant as well as the dielectric loss factor was decreased with the composition. Cole-Cole plots consist of distorted semicircle with increasing diameter as a function of composition indicating improved resistance of the samples. The effect of substitution of Mg and Zn for Ni in NiCuZn ferrite system resulted in improved permeability with high cut off frequency, reduced dielectric losses and enhanced resistance of the samples.

  7. PREFACE: MEM05: The 3rd International Workshop on Mechano-Electromagnetic Properties of Composite Superconductors (Kyoto, Japan, 17 20 July 2005)

    NASA Astrophysics Data System (ADS)

    Osamura, Kozo; Hampshire, Damian

    2005-12-01

    superconductors including the influence of stress and strain on the critical current of practical conductors such as YBCO and ReBCO coated conductors, BiSCCO tapes, MgB2 wires and Nb3Sn filamentary conductors. • The intrinsic strain effects on the critical current density in Nb3Sn YBCO, BiSCCO and MgB2. • Recent advances in the critical current, mechanical properties and reduction in ac losses of HTS tapes and wires. • The compositional and microstructural dependence of E-J characteristics and its explanation based on flux pinning, grain boundary weak links and other mechanisms. • Standardized test methods: international cooperative research work to establish test methods for assessing the mechano-electromagnetic properties of superconductors based on the activities of IEC/TC90 and VAMAS/TWA-16. More than 70 researchers attended the MEM05 workshop, coming from more than ten countries. In total, more than 50 presentations were made at the workshop. In this special issue of Superconductor Science and Technology selected papers have been included that are concerned with the comprehensive scientific research subjects mentioned above. The aim of this issue is to provide a snapshot of some of the current state-of-the-art research, and to promote further international research into the mechano-electromagnetic properties of composite superconductors. The workshop was organized under the activities of the NEDO Grant Project (Applied Superconductivity, 2004EA004) and VAMAS/TWA-16. We wish to thank the following for their contribution to the success of the workshop: AFOSR/AOARD and IEC/TC90-JNC.

  8. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-01-01

    The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  9. Effect of Zr on microstructures and mechanical properties of an Al-Mg-Si-Cu-Cr alloy prepared by low frequency electromagnetic casting

    SciTech Connect

    Meng, Yi Cui, Jianzhong; Zhao, Zhihao; He, Lizi

    2014-06-01

    The Al-1.6Mg-1.2Si-1.1Cu-0.15Cr (all in wt. %) alloys with and without Zr addition prepared by low frequency electromagnetic casting process were investigated by using the optical microscope, scanning electron microscope and transmission electron microscope equipped with energy dispersive analytical X-ray. The effects of Al{sub 3}Zr phases on the microstructures and mechanical properties during solidification, homogenization, hot extrusion and solid solution were studied. The results show that Al{sub 3}Zr phases reduce the grain size by ∼ 29% and promote the formation of an equiaxed grain structure during solidification. Numerous spherical Al{sub 3}Zr dispersoids with 35–60 nm in diameters precipitate during homogenization, and these fine dispersoids change little during subsequent hot extrusion and solid solution. Adding 0.15 wt. % Zr results in no recrystallization after hot extrusion and partial recrystallization after solid solution, while the recrystallized grain size is 400–550 μm in extrusion direction in the Zr-free alloy. In addition, adding 0.15 wt. % Zr can obviously promote Q′ phase precipitation, while the β″ phases are predominant in the alloy without Zr. Adding 0.15 wt. % Zr, the ultimate tensile strength of the T6 treated alloy increases by 45 MPa, while the elongation remains about 16.7%. - Highlights: • Minor Zr can refine as-cast grains of the LFEC Al-Mg-Si-Cu-Cr alloy. • L1{sub 2} Al{sub 3}Zr phases with 35–60 nm in diameter precipitate during homogenization. • L1{sub 2} and DO{sub 22} Al{sub 3}Zr phases result in partial recrystallization after solid solution. • Minor Zr can promote the precipitation of Q′ phases. • Mechanical properties of Al-Mg-Si-Cu-Cr-Zr alloy are higher than those of AA7005.

  10. Effect of the Process Parameters on the Formability, Microstructure, and Mechanical Properties of Thin Plates Fabricated by Rheology Forging Process with Electromagnetic Stirring Method

    NASA Astrophysics Data System (ADS)

    Jin, Chul Kyu; Jang, Chang Hyun; Kang, Chung Gil

    2014-01-01

    A thin plate (150 × 150 × 1.2 mm) with embedded corrugation is fabricated using the rheoforming method. Semisolid slurry is created using the electromagnetic stirring (EMS) system, and the thin plate is made with the forging die at the 200-ton hydraulic press. The cross sections and microstructures of the slurry with and without stirring are examined. To investigate the effect of the process parameters on the formability, microstructure, and mechanical properties of thin plate the slurry is subjected to 16 types of condition for the forging experiment. The 16 types included the following conditions: Whether the EMS is applied or not, three fractions of the solid phase at 35, 45 and 55 pct; two compression velocities at 30 and 300 mm s-1; and four different compression pressures—100, 150, 200 and 250 MPa. The thin plate's formability is enhanced at higher punch velocity for compressing the slurry, and fine solid particles are uniformly distributed, which in turn, enhances the plate's mechanical properties. The pressure between 150 and 200 MPa is an appropriate condition to form thin plates. A thin plate without defects can be created when the slurry at 35 pct of the solid fraction (f s) was applied at the compression velocity of 300 mm s-1 and 150 MPa of pressure. The surface state of thin plate is excellent with 220 MPa of tensile strength and 13.5 pct of elongation. The primary particles are fine over the entire plate, and there are no liquid segregation-related defects.

  11. Electromagnetic properties of microwave sintered ferromagnetic-ferroelectric composites for application in low temperature co-fired ceramic devices

    SciTech Connect

    Yang Qinghui; Zhang Huaiwu; Wen Qiye; Liu Yingli

    2011-04-01

    In this paper, microwave sintering (MS) technology has been applied in the preparation of ferromagnetic-ferroelectric composites. Several kinds of (Ni{sub 0.3}Zn{sub 0.6}Cu{sub 0.1})Fe{sub 2}O{sub 4} (NiCuZn) ferrite with different contents of BaTiO{sub 3}(BT) have been fabricated by MS technology. We found that the sintering time and temperature were significantly reduced from 22 h and 1100 deg. C for the conventional sintering (CS) process to 2 h and 840 deg. C for MS process, respectively. Experiments show that MS treated NiCuZn-BT composites possess both excellent ferromagnetic and ferroelectric properties. For the composites of NiCuZn added with 15% BaTiO{sub 3}, the real part of permittivity is larger than 50 below 20 MHz and the real part of dielectric constant is larger than 18 below 1 GHz. Our results indicate that the microwave sintering method is a potential important technique in LTCC technology.

  12. High frequency electromagnetic properties of interstitial-atom-modified Ce2Fe17NX and its composites

    NASA Astrophysics Data System (ADS)

    Li, L. Z.; Wei, J. Z.; Xia, Y. H.; Wu, R.; Yun, C.; Yang, Y. B.; Yang, W. Y.; Du, H. L.; Han, J. Z.; Liu, S. Q.; Yang, Y. C.; Wang, C. S.; Yang, J. B.

    2014-07-01

    The magnetic and microwave absorption properties of the interstitial atom modified intermetallic compound Ce2Fe17NX have been investigated. The Ce2Fe17NX compound shows a planar anisotropy with saturation magnetization of 1088 kA/m at room temperature. The Ce2Fe17NX paraffin composite with a mass ratio of 1:1 exhibits a permeability of μ ' = 2.7 at low frequency, together with a reflection loss of -26 dB at 6.9 GHz with a thickness of 1.5 mm and -60 dB at 2.2 GHz with a thickness of 4.0 mm. It was found that this composite increases the Snoek limit and exhibits both high working frequency and permeability due to its high saturation magnetization and high ratio of the c-axis anisotropy field to the basal plane anisotropy field. Hence, it is possible that this composite can be used as a high-performance thin layer microwave absorber.

  13. Effects of specimen preparation on the electromagnetic property measurements of solid materials with an automatic network analyzer

    NASA Technical Reports Server (NTRS)

    Long, E. R., Jr.

    1986-01-01

    Effects of specimen preparation on measured values of an acrylic's electomagnetic properties at X-band microwave frequencies, TE sub 1,0 mode, utilizing an automatic network analyzer have been studied. For 1 percent or less error, a gap between the specimen edge and the 0.901-in. wall of the specimen holder was the most significant parameter. The gap had to be less than 0.002 in. The thickness variation and alignment errors in the direction parallel to the 0.901-in. wall were equally second most significant and had to be less than 1 degree. Errors in the measurement f the thickness were third most significant. They had to be less than 3 percent. The following parameters caused errors of 1 percent or less: ratios of specimen-holder thicknesses of more than 15 percent, gaps between the specimen edge and the 0.401-in. wall less than 0.045 in., position errors less than 15 percent, surface roughness, hickness variation in the direction parallel to the 0.401-in. wall less than 35 percent, and specimen alignment in the direction parallel to the 0.401-in. wall mass than 5 degrees.

  14. The BaBar electromagnetic calorimeter

    SciTech Connect

    Stahl, A.

    1997-07-01

    The progress on the design and construction of the BaBar electromagnetic calorimeter including its mechanical structure, the readout system, the mechanical and optical properties of the crystals, and the schedule for the final assembly and testing is summarized.

  15. Electrical wire insulation and electromagnetic coil

    DOEpatents

    Bich, George J.; Gupta, Tapan K.

    1984-01-01

    An electromagnetic coil for high temperature and high radiation application in which glass is used to insulate the electrical wire. A process for applying the insulation to the wire is disclosed which results in improved insulation properties.

  16. Electromagnetic launcher

    SciTech Connect

    Laskaris, E.T.; Chari, M.V.K.

    1990-11-20

    This paper describes an electromagnetic launcher. It comprises: a stationary superconductive coil situated coaxially in a cylindrical vacuum vessel for providing a magnetic field. The superconductive coil having a central aperture, the vacuum vessel having an axially extending bore passing through the central aperture of the superconducting coil; a resistive coil situated coaxially with the superconductive coil and movable axially relative to the stationary superconductive coil, the outer diameter of the resistive coil being smaller than the inner diameter of the bore permitting the resistive coil to pass therethrough; launch activating means coupled to the resistive coil. The launch activating means comprising a shaft joined at one end to the resistive coil, a tube open at both ends, a sliding piston situated in the tube and connected to the other end of the shaft; and power supply means coupled to the resistive coil for providing current of a desired direction and magnitude, so that energization of the resistive coil in the presence of the radial field component of the magnetic field of the superconductive coil creates an axial force on the movable coil, the direction and magnitude of which is dependent on the direction and magnitude of the current in the resistive coil.

  17. Electromagnetic launchers

    NASA Astrophysics Data System (ADS)

    Kolm, H.; Mongeau, P.; Williams, F.

    1980-09-01

    Recent advances in energy storage, switching and magnet technology make electromagnetic acceleration a viable alternative to chemical propulsion for certain tasks, and a means to perform other tasks not previously feasible. Applications include the acceleration of gram-size particles for hypervelocity research and the initiation of fusion by impact, a replacement for chemically propelled artillery, the transportation of cargo and personnel over inaccessible terrain, and the launching of space vehicles to supply massive space operations, and for the disposal of nuclear waste. The simplest launcher of interest is the railgun, in which a short-circuit slide or an arc is driven along two rails by direct current. The most sophisticated studied thus far is the mass driver, in which a superconducting shuttle bucket is accelerated by a line of pulse coils energized by capacitors at energy conversion efficiencies better than 90%. Other accelerators of interest include helical, brush-commutated motors, discrete coil arc commutated drivers, flux compression momentum transformers, and various hybrid electrochemical devices.

  18. Electromagnetic jets from compact objects

    NASA Technical Reports Server (NTRS)

    Michel, F. Curtis

    1987-01-01

    The possibility that at least some astrophysical jets are initially electromagnetic in origin is examined. Subsequent pick-up of ionization would convert such electromagnetic jets into hydrodynamic jets. In such a model, relativistic outflow is formed into highly collimated beams simply through the interaction with the surrounding medium. Forming jets under such general circumstances is encouraging in view of the range of scales that appear to be involved. The overall properties of such jets are largely determined by a single dimensionless parameter: the characteristic electrostatic potential drop rewritten as a particle Lorentz factor. Consequently, the determination of any one observable, such as the total power output, also determines the particle energy scale, the electromagnetic field strengths, etc.

  19. The properties of human body phantoms used in calculations of electromagnetic fields exposure by wireless communication handsets or hand-operated industrial devices.

    PubMed

    Zradziński, Patryk

    2013-06-01

    According to international guidelines, the assessment of biophysical effects of exposure to electromagnetic fields (EMF) generated by hand-operated sources needs the evaluation of induced electric field (E(in)) or specific energy absorption rate (SAR) caused by EMF inside a worker's body and is usually done by the numerical simulations with different protocols applied to these two exposure cases. The crucial element of these simulations is the numerical phantom of the human body. Procedures of E(in) and SAR evaluation due to compliance analysis with exposure limits have been defined in Institute of Electrical and Electronics Engineers standards and International Commission on Non-Ionizing Radiation Protection guidelines, but a detailed specification of human body phantoms has not been described. An analysis of the properties of over 30 human body numerical phantoms was performed which has been used in recently published investigations related to the assessment of EMF exposure by various sources. The differences in applicability of these phantoms in the evaluation of E(in) and SAR while operating industrial devices and SAR while using mobile communication handsets are discussed. The whole human body numerical phantom dimensions, posture, spatial resolution and electric contact with the ground constitute the key parameters in modeling the exposure related to industrial devices, while modeling the exposure from mobile communication handsets, which needs only to represent the exposed part of the human body nearest to the handset, mainly depends on spatial resolution of the phantom. The specification and standardization of these parameters of numerical human body phantoms are key requirements to achieve comparable and reliable results from numerical simulations carried out for compliance analysis against exposure limits or within the exposure assessment in EMF-related epidemiological studies.

  20. A study of synthesis of NiCuZn-ferrite sintering in low temperature by metal nitrates and its electromagnetic property

    NASA Astrophysics Data System (ADS)

    Kim, Chul Won; Koh, Jae Gui

    2003-02-01

    The initial NiCuZn synthetic ferrite was synthesized by thermally decomposing the metal nitrates Fe(NO 3) 3·9H 2O, Zn(NO 3) 2·6H 2O, Ni(NO 3) 2·6H 2O, and Cu(NO 3) 2·3H 2O at 150°C for 24 h, and then we calcined the synthetic ferrite powder at 500°C, pulverized each of those for 3, 6, 9, 12, and 15 h in a steel ball mill, sintered each at 700-1000°C for 1 h, and thus studied their microstructures and electromagnetic properties. We could make the initial specimens chemically bonded in liquid at a low-temperature of 150°C, by using the low melting points less than 200°C of the metal nitrates instead of the mechanical ball-mill pulverization, then narrow a distance between the particles into a molecular one, and thus lower the reaction point of sintering by at least 200-300°C. Their initial permeability was 50-400 and their maximum magnetic induction density and coercive force, 2400 G and 0.3-0.5 Oe each, which was similar to those of NiCuZn ferrite synthesized in the conventional process. In the graph of initial permeability versus frequencies, a 180° rotation of the magnetic domain, which appears in a broad band of micro-wave before and after the resonance frequency, could be perceived.

  1. Effects of Ag{sub 2}O doping on the electromagnetic properties of a BiPbSrCaCuO superconductor

    SciTech Connect

    Lee, Sang Heon; Kim, H. C.

    2001-06-01

    Electromagnetic properties of an Ag{sub 2}O doped and an undoped BiPbSrCaCuO superconductor were evaluated to investigate the effect of the pinning center on the magnetic shielding and suspension/levitation phenomena. The residual magnetization M=M{sup +}{endash}M{sup {minus}} increased with the dopant concentration, a maximum for 2% doping, wherein a fine uniform dispersion of Ag particles was observed. The fine Ag particles form a cluster with increasing dopant as the particles condense with each other and grow, consequently does the number of flux passing through decreases, so the magnetization M decreases. This result indicates that M is proportional to the number of magnetic flux lines passing through the sample, because the smaller the particle size the larger the ratio of the surface area to the volume. Magnetic shielding was evaluated by measuring the induced voltage in the secondary coil by placing the sample in between the primary coil. The voltage was initially set to 0.5 V, and decreased to 0.17 and 0.28 V, respectively, for the undoped and 2% Ag{sub 2}O doped samples. The much less change in the induced voltage for the 2% doped sample is attributed to increased flux shielding by shielding the vortex current. Simultaneous stable levitation and suspension of 2% Ag{sub 2}O doped disk samples weighing 0.3 g were observed, respectively, above (3 mm) and beneath (2 mm) a toroidal permanent magnet under a field cooled condition. The role of flux pinning is discussed to account for the phenomena by considering the hysteretic force function. {copyright} 2001 American Institute of Physics.

  2. PREFACE: MEM07: The 5th Annual Workshop on Mechanical and Electromagnetic Properties of Composite Superconductors (Princeton, NJ, USA, 21 24 August 2007)

    NASA Astrophysics Data System (ADS)

    Larbalestier, D. C.; Osamura, K.; Hampshire, D. P.

    2008-05-01

    -up is a second vital task. As system design is dependent on material development, there is a critical need to study the key issues in developing high performance superconducting materials. The emphases of MEM07 were The mechanical properties of superconductors including the influence of stress and strain on the critical current of practical conductors including YBCO and ReBCO coated conductors, BSCCO tapes, MgB2 wires and Nb3Sn filamentary conductors. The intrinsic strain effects on critical current density in Nb3Sn, YBCO, BSCCO and MgB2. Recent advances in critical current, the mechanical properties and the reduction in ac losses of HTS tapes and wires. The compositional and microstructural dependence of E-J characteristics and explanations based on flux pinning, grain boundary weak-links and other mechanisms. Standardized test-methods: international cooperative research work to establish test methods for assessing the mechano-electromagnetic properties of superconductors based on the activities of IEC/TC90 and VAMAS/TWA-16. More than 60 researchers from more than 12 countries attended the MEM07 workshop, and about 40 presentations were made. A small selection of papers (15) from the workshop are included in this special issue of Superconductor Science and Technology. Taken together with papers published at earlier MEM meetings, this issue provides an updated view of some of the current state-of-the-art research in the mechano-electromagnetic properties of composite superconductors. The workshop was organized under the activities of the NEDO Grant Project (Applied Superconductivity, 2004EA004) and VAMAS/TWA-16. The meeting was organized by a committee composed of David Larbalestier (Conference Chair) aided by MEM05 and MEM06 Conference Chairs Kozo Osamura (Research Institute for Applied Sciences, Kyoto, Japan), Damian Hampshire (Durham University, UK) and Arman Nyilas (CEME). The Program Committee was composed of Ettore Salpietro (European Fusion Development Agreement

  3. Electromagnetic properties of baryon resonances

    NASA Astrophysics Data System (ADS)

    Tiator, Lothar

    2013-10-01

    Longitudinal and transverse transition form factors for most of the four-star nucleon resonances have been obtained from high-quality cross section data and polarization observables measured at MAMI, ELSA, BATES, GRAAL and CEBAF. As an application, we further show how the transition form factors can be used to obtain empirical transverse charge densities. Contour plots of the thus derived densities are shown and compared for the Roper and S11 nucleon resonances.

  4. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  5. Electromagnetic Education in India

    ERIC Educational Resources Information Center

    Bajpai, Shrish; Asif, Siddiqui Sajida; Akhtar, Syed Adnan

    2016-01-01

    Out of the four fundamental interactions in nature, electromagnetics is one of them along with gravitation, strong interaction and weak interaction. The field of electromagnetics has made much of the modern age possible. Electromagnets are common in day-to-day appliances and are becoming more conventional as the need for technology increases.…

  6. Fundamentals of Electromagnetic Phenomena

    NASA Astrophysics Data System (ADS)

    Lorrain, Paul; Corson, Dale R.; Lorrain, Francois

    Based on the classic Electromagnetic Fields and Waves by the same authors, Fundamentals of Electromagnetic Phenomena capitalizes on the older text's traditional strengths--solid physics, inventive problems, and an experimental approach--while offering a briefer, more accessible introduction to the basic principles of electromagnetism.

  7. Broadband electromagnetic analysis of compacted kaolin

    NASA Astrophysics Data System (ADS)

    Bore, Thierry; Wagner, Norman; Cai, Caifang; Scheuermann, Alexander

    2017-01-01

    The mechanical compaction of soil influences not only the mechanical strength and compressibility but also the hydraulic behavior in terms of hydraulic conductivity and soil suction. At the same time, electric and dielectric parameters are increasingly used to characterize soil and to relate them with mechanic and hydraulic parameters. In the presented study electromagnetic soil properties and suction were measured under defined conditions of standardized compaction tests. The impact of external mechanical stress conditions of nearly pure kaolinite was analyzed on soil suction and broadband electromagnetic soil properties. An experimental procedure was developed and validated to simultaneously determine mechanical, hydraulic and broadband (1 MHz-3 GHz) electromagnetic properties of the porous material. The frequency dependent electromagnetic properties were modeled with a classical mixture equation (advanced Lichtenecker and Rother model, ALRM) and a hydraulic-mechanical-electromagnetic coupling approach was introduced considering water saturation, soil structure (bulk density, porosity), soil suction (pore size distribution, water sorption) as well as electrical conductivity of the aqueous pore solution. Moreover, the relaxation behavior was analyzed with a generalized fractional relaxation model concerning a high-frequency water process and two interface processes extended with an apparent direct current conductivity contribution. The different modeling approaches provide a satisfactory agreement with experimental data for the real part. These results show the potential of broadband electromagnetic approaches for quantitative estimation of the hydraulic state of the soil during densification.

  8. Structural and dynamic electromagnetic properties of Ni0.27 Cu0.10 Zn0.63 Alx Fe2-x O4

    NASA Astrophysics Data System (ADS)

    Hossen, M. Belal; Hossain, A. K. M. Akther

    2015-08-01

    The influence of Al substitution on the structural and electromagnetic properties of Ni0.27Cu0.10Zn0.63AlxFe2 - xO4; (where x = 0.0 to x = 0.16 with step = 0.02) prepared by the combustion technique, has been investigated. X-ray diffraction analysis confirms the presence of single phase cubic spinel structure without any secondary phase. The lattice constant, theoretical density, bulk density and average grain size decreases with increasing Al content. B-H loops have been traced for all the compositions and the various hysteresis parameters like saturation induction, coercivity, remanance, remanance ratio and power loss have been studied as a function of Al content. The saturation induction and the initial permeability increases with sintering temperature up to 1150 °C where the maximum bulk density is obtained, while for higher sintering temperature they decrease. The variation of complex initial permeability for Al substituted NiCuZn ferrites can be presented as a form of semicircle so called the Cole-Cole plot and the relaxation phenomena were explained with various shapes of the plots. The analysis of complex impedance spectra by an equivalent circuit model were used to separate the grain and grain boundary resistance of various Ni0.27 Cu0.10 Zn0.63 Alx Fe2 - x O4 . The impedance plot showed the first semicircle at high frequency which corresponds to grain effect and the second semicircle at lower frequency which corresponds to grain boundary (conduction phenomenon). Both grain and grain boundary resistance increases with increasing Al content and the relative increase of grain resistance is larger than the grain boundary resistance. The frequency dependent conductivity results support the double (Jonscher's modified) power law,σT (ω) = σ (o) +A1 ω n1 +A2 ω n2 , and the results showed evidence of three types of conduction process at room temperature: (i) low frequency conductivity is due to long-range ordering (frequency independent or its tendency

  9. Electromagnetic nucleon form factors

    SciTech Connect

    Bender, A.; Roberts, C.D.; Frank, M.R.

    1995-08-01

    The Dyson-Schwinger equation framework is employed to obtain expressions for the electromagnetic nucleon form factor. In generalized impulse approximation the form factor depends on the dressed quark propagator, the dressed quark-photon vertex, which is crucial to ensuring current conservation, and the nucleon Faddeev amplitude. The approach manifestly incorporates the large space-like-q{sup 2} renormalization group properties of QCD and allows a realistic extrapolation to small space-like-q{sup 2}. This extrapolation allows one to relate experimental data to the form of the quark-quark interaction at small space-like-q{sup 2}, which is presently unknown. The approach provides a means of unifying, within a single framework, the treatment of the perturbative and nonperturbative regimes of QCD. The wealth of experimental nucleon form factor data, over a large range of q{sup 2}, ensures that this application will provide an excellent environment to test, improve and extend our approach.

  10. Young's experiment with electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Carrasquilla, Juan; Garcia-Sucerquia, Jorge

    2006-10-01

    We discuss Young's experiment with electromagnetic random fields at arbitrary states of coherence and polarization within the framework of the electric spatial coherence wavelets. The use of this approach for the electromagnetic spatial coherence theory allows us to envisage the existence of polarization domains inside the observation plane. We show that it is possible to locally control those polarization domains by means of the correlation properties of the electromagnetic wave. To show the validity of this alternative approach, we derive by means of numerical modeling the classical Fresnel-Arago interference laws.

  11. Review on electromagnetic welding of dissimilar materials

    NASA Astrophysics Data System (ADS)

    Shanthala, K.; Sreenivasa, T. N.

    2016-12-01

    Electromagnetic welding (EMW) is a highspeed joining technique that is used to join similar or dissimilar metals, as well as metals to non-metals. This technique uses electromagnetic force to mainly join conductive materials. Unlike conventional joining processes, the weld interface does not melt, thus keeping the material properties intact. Extremely high velocity and strain rate involved in the process facilitate extending the EMW technique for joining several materials. In this paper, the research and progress in electromagnetic welding are reviewed from various perspectives to provide a basis for further research.

  12. Interaction of electromagnetic fields and biological tissues

    NASA Astrophysics Data System (ADS)

    Darshan Shrivastava, Bhakt; Barde, Ravindra; Mishra, Ashutosh; Phadke, S.

    2014-09-01

    This paper deals with the electromagnetic field interact in biological tissues. It is actually one of the important challenges for the electromagnetic field for the recent years. The experimental techniques are use in Broad-band Dielectric Measurement (BDM) with LCR meters. The authors used Bones and scales of Fish taken from Narmada River (Rajghat Dist. Barwani) as biological tissues. Experimental work carried out done in inter-university consortium (IUC) Indore. The major difficulties that appear are related to the material properties, to the effect of the electromagnetic problem and to the thermal model of the biological tissues.

  13. Principles of electromagnetic theory

    SciTech Connect

    Kovetz, A.H. )

    1990-01-01

    This book emphasizes the fundamental understanding of the laws governing the behavior of charge and current carrying bodies. Electromagnetism is presented as a classical theory, based-like mechanics-on principles that are independent of the atomic constitution of matter. This book is unique among electromagnetic texts in its treatment of the precise manner in which electromagnetism is linked to mechanics and thermodynamics. Applications include electrostriction, piezoelectricity, ferromagnetism, superconductivity, thermoelectricity, magnetohydrodynamics, radiation from charged particles, electromagnetic wave propagation and guided waves. There are many worked examples of dynamical and thermal effects of electromagnetic fields, and of effects resulting from the motion of bodies.

  14. Calculation of electromagnetic force in electromagnetic forming process of metal sheet

    SciTech Connect

    Xu Da; Liu Xuesong; Fang Kun; Fang Hongyuan

    2010-06-15

    Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

  15. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen

    2001-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  16. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

    2003-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  17. Fabrication of monodispersed nickel flower-like architectures via a solvent-thermal process and analysis of their magnetic and electromagnetic properties

    NASA Astrophysics Data System (ADS)

    Kong, Jing; Liu, Wei; Wang, Fenglong; Wang, Xinzhen; Luan, Liqiang; Liu, Jiurong; Wang, Yuan; Zhang, Zijun; Itoh, Masahiro; Machida, Ken-ichi

    2011-11-01

    Monodispersed Ni flower-like architectures with size of 1-2 μm were synthesized through a facile solvent-thermal process in 1,2-propanediol solution in the presence of polyethylene glycol (PEG) and sodium alkali for electromagnetic absorption application. The Ni architectures are composed of nanoflakes, which assemble to form three dimensional flower-like structure, and the thickness of nanoflakes is about 10-40 nm. A possible formation mechanism for Ni flower-like architectures was proposed and it was confirmed by the control experiments. The Ni architectures exhibited a saturation magnetization ( Ms) of 47.7 emu/g and a large coercivity ( Hcj) of 332.3 Oe. The epoxy resin composites with 20 vol% Ni sample provided good electromagnetic wave absorption performance (reflection loss <-20 dB) in the range of 2.8-6.3 GHz over absorber thickness of 2.6-5.0 mm.

  18. Fabrication of monodispersed nickel flower-like architectures via a solvent-thermal process and analysis of their magnetic and electromagnetic properties

    SciTech Connect

    Kong Jing; Liu Wei; Wang Fenglong; Wang Xinzhen; Luan Liqiang; Liu Jiurong; Wang Yuan; Zhang Zijun; Itoh, Masahiro; Machida, Ken-ichi

    2011-11-15

    Monodispersed Ni flower-like architectures with size of 1-2 {mu}m were synthesized through a facile solvent-thermal process in 1,2-propanediol solution in the presence of polyethylene glycol (PEG) and sodium alkali for electromagnetic absorption application. The Ni architectures are composed of nanoflakes, which assemble to form three dimensional flower-like structure, and the thickness of nanoflakes is about 10-40 nm. A possible formation mechanism for Ni flower-like architectures was proposed and it was confirmed by the control experiments. The Ni architectures exhibited a saturation magnetization (M{sub s}) of 47.7 emu/g and a large coercivity (H{sub cj}) of 332.3 Oe. The epoxy resin composites with 20 vol% Ni sample provided good electromagnetic wave absorption performance (reflection loss <-20 dB) in the range of 2.8-6.3 GHz over absorber thickness of 2.6-5.0 mm. - Graphical abstract: Monodispersed Ni flower-like architectures composed of nanoflakes were synthesized through a facile solvent-thermal process. The Ni architectures exhibited a large coercivity and enhanced electromagnetic wave absorption in GHz. Highlights: > Flower-like architectures composed of nanoflakes. > A possible formation mechanism for Ni flower-like architectures was proposed. > Sodium alkali, PEG, and NaCl played the important roles in the final morphology. > Ni architectures exhibited a large coercivity (H{sub cj}) of 332.3 Oe. > Efficient electromagnetic absorption (RL<-20 dB) was provided in 2.8-6.3 GHz.

  19. Morphology-controlled synthesis and novel microwave electromagnetic properties of hollow urchin-like chain Fe-doped MnO{sub 2} under 10 T high magnetic field

    SciTech Connect

    Yuping, Duan; Jia, Zhang; Hui, Jing; Shunhua, Liu

    2011-05-15

    Fe-doped MnO{sub 2} with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO{sub 2} with Fe, the relative complex permittivity of MnO{sub 2} and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO{sub 2} exhibits good microwave absorption capability. -- Graphical Abstract: Fe-doped MnO{sub 2} with a hollow sea urchin-like ball chain shape was first synthesized in a high magnetic field of 10 T via a simple chemical process. Display Omitted Highlights: {yields} Fe-doped MnO{sub 2} with a hollow sea urchin-like ball chain shape was first synthesized. {yields} We investigated formation mechanism and electromagnetic properties of the Fe-doped MnO{sub 2}. {yields} By doping MnO{sub 2} with Fe, the electromagnetic properties are improved obviously.

  20. Electromagnetic Radiation Analysis

    DTIC Science & Technology

    1978-04-10

    A methodology is given for determining whether electromagnetic radiation of sufficient strength to cause performance degradation to the test item...exists at the test item location. The results of an electromagnetic radiation effects test are used to identify the radio frequencies and electromagnetic ... radiation levels to which the test item is susceptible. Further, using a test bed, comparisons are made with the representative signal levels to

  1. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Kees de Jager

    2004-08-01

    Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor.

  2. Controlling electromagnetic scattering with wire metamaterial resonators.

    PubMed

    Filonov, Dmitry S; Shalin, Alexander S; Iorsh, Ivan; Belov, Pavel A; Ginzburg, Pavel

    2016-10-01

    Manipulation of radiation is required for enabling a span of electromagnetic applications. Since properties of antennas and scatterers are very sensitive to the surrounding environment, macroscopic artificially created materials are good candidates for shaping their characteristics. In particular, metamaterials enable controlling both dispersion and density of electromagnetic states, available for scattering from an object. As a result, properly designed electromagnetic environments could govern wave phenomena and tailor various characteristics. Here electromagnetic properties of scattering dipoles, situated inside a wire medium (metamaterial), are analyzed both numerically and experimentally. The effect of the metamaterial geometry, dipole arrangement inside the medium, and frequency of the incident radiation on the scattering phenomena is studied in detail. It is shown that the resonance of the dipole hybridizes with Fabry-Perot modes of the metamaterial, giving rise to a complete reshaping of electromagnetic properties. Regimes of controlled scattering suppression and super-scattering are experimentally observed. Numerical analysis is in agreement with the experiment, performed at the GHz spectral range. The reported approach to scattering control with metamaterials could be directly mapped into optical and infrared spectral ranges by employing scalability properties of Maxwell's equations.

  3. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  4. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  5. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  6. Electromagnetically Operated Counter

    DOEpatents

    Goldberg, H D; Goldberg, M I

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  7. Ice-templated synthesis of multifunctional three dimensional graphene/noble metal nanocomposites and their mechanical, electrical, catalytic, and electromagnetic shielding properties

    PubMed Central

    Sahoo, P. K.; Aepuru, Radhamanohar; Panda, Himanshu Sekhar; Bahadur, D.

    2015-01-01

    In-situ homogeneous dispersion of noble metals in three-dimensional graphene sheets is a key tactic for producing macroscopic architecture, which is desirable for practical applications, such as electromagnetic interference shielding and catalyst. We report a one-step greener approach for developing porous architecture of 3D-graphene/noble metal (Pt and Ag) nanocomposite monoliths. The resulting graphene/noble metal nanocomposites exhibit a combination of ultralow density, excellent elasticity, and good electrical conductivity. Moreover, in order to illuminate the advantages of the 3D-graphene/noble metal nanocomposites, their electromagnetic interference (EMI) shielding and electrocatalytic performance are further investigated. The as-synthesized 3D-graphene/noble metal nanocomposites exhibit excellent EMI shielding effectiveness when compared to bare graphene; the effectiveness has an average of 28 dB in the 8.2–12.4 GHz X-band range. In the electro-oxidation of methanol, the 3D-graphene/Pt nanocomposite also exhibits significantly enhanced electrocatalytic performance and stability than compared to reduced graphene oxide/Pt and commercial Pt/C. PMID:26638827

  8. [Dynamics of biomacromolecules in coherent electromagnetic radiation field].

    PubMed

    Leshcheniuk, N S; Apanasevich, E E; Tereshenkov, V I

    2014-01-01

    It is shown that induced oscillations and periodic displacements of the equilibrium positions occur in biomacromolecules in the absence of electromagnetic radiation absorption, due to modulation of interaction potential between atoms and groups of atoms forming the non-valence bonds in macromolecules by the external electromagnetic field. Such "hyperoscillation" state causes inevitably the changes in biochemical properties of macromolecules and conformational transformation times.

  9. Electromagnetic ion beam instabilities

    NASA Technical Reports Server (NTRS)

    Gary, S. P.; Foosland, D. W.; Smith, C. W.; Lee, M. A.; Goldstein, M. L.

    1984-01-01

    The linear theory of electromagnetic instabilities driven by an energetic ion beam streaming parallel to a magnetic field in a homogeneous Vlasov plasma is considered. Numerical solutions of the full dispersion equation are presented. At propagation parallel to the magnetic field, there are four distinct instabilities. A sufficiently energetic beam gives rise to two unstable modes with right-hand polarization, one resonant with the beam, the other nonresonant. A beam with sufficiently large T (perpendicular to B)/T (parallel to B) gives rise to the left-hand ion cyclotron anisotropy instability at relatively small beam velocities, and a sufficiently hot beam drives unstable a left-hand beam resonant mode. The parametric dependences of the growth rates for the three high beam velocity instabilities are presented here. In addition, some properties at oblique propagation are examined. It is demonstrated that, as the beam drift velocity is increased, relative maxima in growth rates can arise at harmonics of the ion cyclotron resonance for both right and left elliptically polarized modes.

  10. SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS

    SciTech Connect

    Steven D. Novack; Dale K. Kotter; Dennis Slafer; Patrick Pinhero

    2008-08-01

    This research explores a new efficient approach for producing electricity from the abundant energy of the sun. A nanoantenna electromagnetic collector (NEC) has been designed, prototyped, and tested. Proof of concept has been validated. The device targets mid-infrared wavelengths where conventional photovoltaic (PV) solar cells do not respond but is abundant in solar energy. The initial concept of designing NEC antennas was based on scaling of radio frequency antenna theory. This approach has proven unsuccessful by many due to not fully understanding and accounting for the optical behavior of materials in the THz region. Also until recent years the nanofabrication methods were not available to fabricate the optical antenna elements. We have addressed and overcome both technology barriers. Several factors were critical in successful implementation of NEC including: 1) frequency-dependent modeling of antenna elements, 2) selection of materials with proper THz properties and 3) novel manufacturing methods that enable economical large-scale manufacturing. The work represents an important step toward the ultimate realization of a low-cost device that will collect as well as convert this radiation into electricity, which will lead to a wide spectrum, high conversion efficiency, and low cost solution to complement conventional PVs.

  11. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    PubMed Central

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB). The 3D lamellar graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  12. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin-dependent electron transport of a waveguide with Rashba spin-orbit coupling in an electromagnetic field

    NASA Astrophysics Data System (ADS)

    Xiao, Xian-Bo; Li, Xiao-Mao; Chen, Yu-Guang

    2009-12-01

    We investigate theoretically the spin-dependent electron transport in a straight waveguide with Rashba spin-orbit coupling (SOC) under the irradiation of a transversely polarized electromagnetic (EM) field. Spin-dependent electron conductance and spin polarization are calculated as functions of the emitting energy of electrons or the strength of the EM field by adopting the mode matching approach. It is shown that the spin polarization can be manipulated by external parameters when the strength of Rashba SOC is strong. Furthermore, a sharp step structure is found to exist in the total electron conductance. These results can be understood by the nontrivial Rashba subbands intermixing and the electron intersubband transition when a finite-range transversely polarized EM field irradiates a straight waveguide.

  13. Electromagnetic Characterization of a Marx Pulse Generator.

    DTIC Science & Technology

    1981-07-01

    This report reviews the electrical characteristics of the Marx pulser installed in ATLAS I (TRESTLE) facility. Various individual components of the...pulser, e.g., monocone switch, central Marx column and peaker arms are studied for their electromagnetic properties. The resulting design curves and

  14. Electromagnetism in the Movies.

    ERIC Educational Resources Information Center

    Everitt, Lori R.; Patterson, Evelyn T.

    1999-01-01

    Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

  15. An opening electromagnetic transducer

    NASA Astrophysics Data System (ADS)

    Sun, Yanhua; Kang, Yihua

    2013-12-01

    Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

  16. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  17. Simulation of electromagnetic aspects of lightning

    NASA Technical Reports Server (NTRS)

    Baum, C. E.

    1980-01-01

    Electromagnetic processes peculiar to the direct-strike case are reviewed with respect to their implications for lightning electromagnetic simulation. At low frequencies (quasistatic) there are important surface-charge-density and corona effects in addition to the surface-current-density effects. At resonant frequencies the frequency-spectral content of the excitation and properties of the arc (attachment, detachment, time history, spatial distribution, resistance, etc.) are significant. Of great complexity in all this are nonlinear aspects of the arc and corona around the system of interest. The complexity of these various processes requires rigor in the simulator design. Potential simulation concepts are presented and their relative merits are discussed.

  18. Interpreting Electromagnetic Reflections In Glaciology

    NASA Astrophysics Data System (ADS)

    Eisen, O.; Nixdorf, U.; Wilhelms, F.; Steinhage, D.; Miller, H.

    Electromagnetic reflection (EMR) measurements are active remote sensing methods that have become a major tool for glaciological investigations. Although the basic pro- cesses are well understood, the unambiguous interpretation of EMR data, especially internal layering, still requires further information. The Antacrtic ice sheet provides a unique setting for investigating the relation between physical­chemical properties of ice and EMR data. Cold ice, smooth surface topography, and low accumulation facilitates matters to use low energy ground penetrating radar (GPR) devices to pene- trate several tens to hundreds of meters of ice, covering several thousands of years of snow deposition history. Thus, sufficient internal layers, primarily of volcanic origin, are recorded to enable studies on a local and regional scale. Based on dated ice core records, GPR measurements at various frequencies, and airborne radio-echo sound- ing (RES) from Dronning Maud Land (DML), Antarctica, combined with numerical modeling techniques, we investigate the influence of internal layering characteristics and properties of the propagating electromagnetic wave on EMR data.

  19. Electromagnetic scattering from turbulent plasmas

    SciTech Connect

    Resendes, D.G. Instituto Superior Tecnico, Rua Rovisco Pais, Lisboa )

    1992-11-15

    A self-consistent multiple-scattering theory of vector electromagnetic waves scattered from a turbulent plasma is presented. This approach provides a general and systematic treatment to all orders in turbulence of the scattering of electromagnetic waves in terms of the properties of the turbulent structure of the scattering system and is applicable in the full regime from underdense to overdense plasmas. To illustrate the theory, a plasma consisting of a finite number density of discrete scatterers with a simple geometry and statistical properties is chosen. In this approach the exact solution for a single scatterer is obtained first. From it the configuration-dependent solution for {ital N} scatterers is constructed. Rather than solving explicitly for this solution and then averaging, the averaging operation will be taken first in order to find an approximate equation obeyed by the mean or coherent field. The coherent and incoherent scattering are then determined in terms of the coherent field and the backscatter is evaluated. The coherent and incoherent scattering, our principal results, are expressed in a plane-wave basis in a form suitable for numerical computation. A number of interesting phenomena which may readily be incorporated into the theory are indicated.

  20. Compton Sources of Electromagnetic Radiation

    SciTech Connect

    Geoffrey Krafft,Gerd Priebe

    2011-01-01

    When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

  1. Monitoring Polymer Curing Via Electromagnetic Impedance

    NASA Technical Reports Server (NTRS)

    Freeman, William T.; Covington, John C.; Kranbuehl, David E.; Hoff, Melanie; Delos, Susan

    1992-01-01

    New nondestructive in-situ electromagnetic-impedance measurement technique senses cure-processing properties of high-temperature, high-performance thermostat and thermoplastic resins. Continuous frequency-dependent measurement and analysis performed during curing cycle. Monitors and measures molecular properties of polymeric resin in liquid and solid states. Applications include nondestructive means for evaluation of materials, determination of "window" boundaries of curing cycles of thermoplastics and thermoset resins, and for online, closed-loop control of curing cycles.

  2. Effect of covalent modification of graphene nanosheets on the electrical property and electromagnetic interference shielding performance of a water-borne polyurethane composite.

    PubMed

    Hsiao, Sheng-Tsung; Ma, Chen-Chi M; Tien, Hsi-Wen; Liao, Wei-Hao; Wang, Yu-Sheng; Li, Shin-Ming; Yang, Chih-Yu; Lin, Sheng-Chi; Yang, Ruey-Bin

    2015-02-04

    Flexible and lightweight graphene nanosheet (GN)/waterborne polyurethane (WPU) composites which exhibit high electrical conductivity and electromagnetic shielding performance were prepared. Covalently modifying GNs with aminoethyl methacrylate (AEMA; AEMA-GNs) through free radical polymerization effectively inhibited the restacking and aggregation of the GNs because of the -NH3(+) functional groups grafted on the AEMA-GNs. Moreover, the AEMA-GNs exhibited high compatibility with a WPU matrix with grafted sulfonated functional groups because of the electrostatic attraction, which caused the AEMA-GNs to homogeneously disperse in the WPU matrix. This homogeneous distribution enabled the GNs to form electrically conductive networks. Furthermore, AEMA-GNs with different amounts of AEMA segments were introduced into the WPU matrix, and the effects of the surface chemistry of the GNs on the electrical conductivity and EMI shielding performance of composites were investigated. AEMA-GN/WPU composites with a GN loading of 5 vol % exhibited remarkable electrical conductivity (approximately 43.64 S/m) and EMI shielding effectiveness (38 dB) over the frequency of 8.2 to 12.4 GHz.

  3. Resolution in Electromagnetic Prospecting

    NASA Astrophysics Data System (ADS)

    Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Schramm, K. A.

    2014-12-01

    Low-frequency electromagnetic (EM) signals are commonly used in geophysical exploration of the shallow subsurface. Sensitivity to conductivity implies they are particularly useful for inferring fluid content of porous media. However, low-frequency EM wavefields are diffusive, and have significantly larger wavelengths compared to seismic signals of equal frequency. The wavelength of a 30 Hz sinusoid propagating with seismic velocity 3000 m/s is 100 m, whereas an analogous EM signal diffusing through a conductive body of 0.1 S/m (clayey shale) has wavelength 1825 m. The larger wavelength has implications for resolution of the EM prospecting method. We are investigating resolving power of the EM method via theoretical and numerical experiments. Normal incidence plane wave reflection/transmission by a thin geologic bed is amenable to analytic solution. Responses are calculated for beds that are conductive or resistive relative to the host rock. Preliminary results indicate the classic seismic resolution/detection limit of bed thickness ~1/8 wavelength is not achieved. EM responses for point or line current sources recorded by general acquisition geometries are calculated with a 3D finite-difference algorithm. These exhibit greater variability which may allow inference of bed thickness. We also examine composite responses of two point scatterers with separation when illuminated by an incident EM field. This is analogous to the Rayleigh resolution problem of estimating angular separation between two light sources. The First Born Approximation implies that perturbations in permittivity, permeability, and conductivity have different scattering patterns, which may be indicators of EM medium properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Electromagnetic interference reduction design of alternating integrator for EAST

    NASA Astrophysics Data System (ADS)

    Liu, D. M.; Wan, B. N.; Li, J.; Wang, Y.; Shen, B.; Gong, X. Z.; He, Y. G.

    2016-11-01

    An alternating integrator has been designed for the Experimental Advanced Superconducting Tokamak that is intended for long pulse operation of up to 1000 s. The electromagnetic operating environment for the device is so complex that it could affect the performance of the integrator. The new integrator system is carefully designed and actualized based on specific reduced electromagnetic interference requirements, which were formulated based on consideration of processing of the input signals, the isolation properties, and the circuit board layout and grounding. The developed integrator shows excellent electromagnetic compatibility and low-drift properties.

  5. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Sun, Weimin; El-Sharawy, El-Budawy; Aberle, James T.; Birtcher, Craig R.; Peng, Jian; Tirkas, Panayiotis A.

    1992-01-01

    The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program continues its research on variety of main topics identified and recommended by the Advisory Task Force of the program. The research activities center on issues that advance technology related to helicopter electromagnetics. While most of the topics are a continuation of previous works, special effort has been focused on some of the areas due to recommendations from the last annual conference. The main topics addressed in this report are: composite materials, and antenna technology. The area of composite materials continues getting special attention in this period. The research has focused on: (1) measurements of the electrical properties of low-conductivity materials; (2) modeling of material discontinuity and their effects on the scattering patterns; (3) preliminary analysis on interaction of electromagnetic fields with multi-layered graphite fiberglass plates; and (4) finite difference time domain (FDTD) modeling of fields penetration through composite panels of a helicopter.

  6. Controlling the Electromagnetic Field Confinement with Metamaterials

    PubMed Central

    Bonache, Jordi; Zamora, Gerard; Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Martín, Ferran

    2016-01-01

    The definition of a precise illumination region is essential in many applications where the electromagnetic field should be confined in some specific volume. By using conventional structures, it is difficult to achieve an adequate confinement distance (or volume) with negligible levels of radiation leakage beyond it. Although metamaterial structures and metasurfaces are well-known to provide high controllability of their electromagnetic properties, this feature has not yet been applied to solve this problem. We present a method of electromagnetic field confinement based on the generation of evanescent waves by means of metamaterial structures. With this method, the confinement volume can be controlled, namely, it is possible to define a large area with an intense field without radiation leakage. A prototype working in the microwave region has been implemented, and very good agreement between the measurements and the theoretical prediction of field distribution has been obtained. PMID:27886230

  7. Controlling the Electromagnetic Field Confinement with Metamaterials

    NASA Astrophysics Data System (ADS)

    Bonache, Jordi; Zamora, Gerard; Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Martín, Ferran

    2016-11-01

    The definition of a precise illumination region is essential in many applications where the electromagnetic field should be confined in some specific volume. By using conventional structures, it is difficult to achieve an adequate confinement distance (or volume) with negligible levels of radiation leakage beyond it. Although metamaterial structures and metasurfaces are well-known to provide high controllability of their electromagnetic properties, this feature has not yet been applied to solve this problem. We present a method of electromagnetic field confinement based on the generation of evanescent waves by means of metamaterial structures. With this method, the confinement volume can be controlled, namely, it is possible to define a large area with an intense field without radiation leakage. A prototype working in the microwave region has been implemented, and very good agreement between the measurements and the theoretical prediction of field distribution has been obtained.

  8. Ten-gram scale SiC@SiO2 nanowires: high-yield synthesis towards industrialization, in situ growth mechanism and their peculiar photoluminescence and electromagnetic wave absorption properties.

    PubMed

    Li, Z J; Yu, H Y; Song, G Y; Zhao, J; Zhang, H; Zhang, M; Meng, A L; Li, Q D

    2017-02-01

    SiC@SiO2 nanowires, as a functional nanocomposite, have attracted widespread attention due to their fascinating performance and broad application prospect. However, the low-cost, high yield preparation of large-scale SiC@SiO2 nanowires is still a bottleneck, which hinders their industrial application. Herein, a carbothermal reduction strategy has been developed to synthesize SiC@SiO2 nanowires, which breaks through the handicap of the traditional growth pattern that uses the aid of a substrate. Systematic characterization results illustrate that the yield of the as-obtained products greatly depends on the heating rate, and ten-gram scale SiC@SiO2 nanowires (∼27.2 g) composed of a cubic β-SiC core and homogeneous amorphous SiO2 coating are achieved under the optimum process parameters. The in situ mechanisms of expansion-insertion-growth and inhibition of expansion-package-obstruction are proposed to rationally interpret the growth process of SiC@SiO2 nanowires and the effect of various heating rates, respectively. Furthermore, the SiC@SiO2 nanowires display violet-blue photoluminescence and electromagnetic wave absorption properties. This study not only provides some beneficial suggestions for the commercial production of SiC@SiO2 nanowires, but also reveals promising applications of SiC@SiO2 nanowires in the optical and electromagnetic shielding fields. Moreover, the developed novel in situ growth mechanism enriches the growth theory of one-dimension nanomaterials and offers inspiration for their industrial-scale production.

  9. Nonreciprocal Electromagnetic Devices in Gyromagnetic Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Yuan; Liu, Rong-Juan; Gan, Lin; Fu, Jin-Xin; Lian, Jin

    2014-01-01

    Gyromagnetic photonic crystal (GPC) offers a promising way to realize robust transport of electromagnetic waves against backscattering from various disorders, perturbations and obstacles due to existence of unique topological electromagnetic states. The dc magnetic field exerting upon the GPC brings about the time-reversal symmetry breaking, splits the band degeneracy and opens band gaps where the topological chiral edge states (CESs) arise. The band gap can originate either from long-range Bragg-scattering effect or from short-range localized magnetic surface plasmon resonance (MSP). These topological edge states can be explored to construct backscattering-immune one-way waveguide and other nonreciprocal electromagnetic devices. In this paper we review our recent theoretical and experimental studies of the unique electromagnetic properties of nonreciprocal devices built in GPCs. We will discuss various basic issues like experimental instrumental setup, sample preparations, numerical simulation methods, tunable properties against magnetic field, band degeneracy breaking and band gap opening and creation of topological CESs. We will investigate the unidirectional transport properties of one-way waveguide under the influence of waveguide geometries, interface morphologies, intruding obstacles, impedance mismatch, lattice disorders, and material dissipation loss. We will discuss the unique coupling properties between one-wave waveguide and resonant cavities and their application as novel one-way bandstop filter and one-way channel-drop filter. We will also compare the CESs created in the Bragg-scattering band gap and the MSP band gap under the influence of lattice disorders. These results can be helpful for designing and exploring novel nonreciprocal electromagnetic devices for optical integration and information processing.

  10. Electromagnetic pion form factor

    SciTech Connect

    Roberts, C.D.

    1995-08-01

    A phenomenological Dyson-Schwinger/Bethe-Salpeter equation approach to QCD, formalized in terms of a QCD-based model field theory, the Global Color-symmetry Model (GCM), was used to calculate the generalized impulse approximation contribution to the electromagnetic pion form factor at space-like q{sup 2} on the domain [0,10] GeV{sup 2}. In effective field theories this form factor is sometimes understood as simply being due to Vector Meson Dominance (VMD) but this does not allow for a simple connection with QCD where the VMD contribution is of higher order than that of the quark core. In the GCM the pion is treated as a composite bound state of a confined quark and antiquark interacting via the exchange of colored vector-bosons. A direct study of the quark core contribution is made, using a quark propagator that manifests the large space-like-q{sup 2} properties of QCD, parameterizes the infrared behavior and incorporates confinement. It is shown that the few parameters which characterize the infrared form of the quark propagator may be chosen so as to yield excellent agreement with the available data. In doing this one directly relates experimental observables to properties of QCD at small space-like-q{sup 2}. The incorporation of confinement eliminates endpoint and pinch singularities in the calculation of F{sub {pi}}(q{sup 2}). With asymptotic freedom manifest in the dressed quark propagator the calculation yields q{sup 4}F{sub {pi}}(q{sup 2}) = constant, up to [q{sup 2}]- corrections, for space-like-q{sup 2} {approx_gt} 35 GeV{sup 2}, which indicates that soft, nonperturbative contributions dominate the form factor at presently accessible q{sup 2}. This means that the often-used factorization Ansatz fails in this exclusive process. A paper describing this work was submitted for publication. In addition, these results formed the basis for an invited presentation at a workshop on chiral dynamics and will be published in the proceedings.

  11. Electromagnetic transport properties and magnetoresistance of La{sub 0.7}Ca{sub 0.2}Sr{sub 0.1}MnO{sub 3}-Ag composites prepared by electroless process

    SciTech Connect

    Xiong, C.S. Cui, Y.F.; Xiong, Y.H.; Pi, H.L.; Bao, X.C.; Huang, Q.P.; Zeng, Y.; Wei, F.F.; Zheng, C.F.; Zhu, J.

    2008-09-15

    A series of bulk polycrystalline La{sub 0.7}Ca{sub 0.2}Sr{sub 0.1}MnO{sub 3} (LCSMO)-Ag composites were prepared by electroless plating process and several kinds of physical properties have been studied systemically. According to the results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and electromagnetic transport properties, we can see that Ag-added segregated at the surfaces or interfaces of LCSMO grains. The metal-insulator transition temperature (T{sub P}) and Curie temperature (T{sub c}) were almost unchanged but {rho} decreased with increasing plating time. We also observed Ag-added can significantly enhance the magnetoresistance (MR) near T{sub P} under a low applied field (3000 Oe) and the room temperature MR reached to 35% under 20 kOe, which is encouraging for practical applications. We can suggest that improved grain boundary effect by Ag-added is responsible for the enhancement. - Graphical abstract: Magnetic field dependence of the MR for the composites at 298 K. The inset is the different silver-plating time dependence of the variation of MR at 2 T.

  12. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  13. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  14. Seismic electromagnetic study in China

    NASA Astrophysics Data System (ADS)

    Huang, Qinghua

    2016-04-01

    Seismo-electromagnetism is becoming a hot interdisciplinary study in both geosciences and electromagnetism. Numerous electromagnetic changes at a broad range of frequencies associated with earthquakes have been reported independently. There are some attempts of applying such electromagnetic data to short-term earthquake prediction. Although due to the complexity of seismogenic process and underground structure, the seismic electromagnetic phenomena cannot be fully understood, the seismic electromagnetic study plays a key role in the mitigation of seismic hazard. China is one of the countries which have the earliest reports on seismo-electromagnetic phenomena. The seismic electromagnetic study in China started in late 1960's. There are almost 50 years continuous observation data up to now, which provides a unique database for seismo-electromagnetic study not only in China, but also in the world. Therefore, seismo-electromagnetic study in China is interested broadly by international communities of geosciences and electromagnetism. I present here a brief review on seismic electromagnetic study in China, especially focusing on geo-electromagnetic observation and empirical prediction based on the observation data. After summarizing various electromagnetic observations such as apparent resistivity, geoelectric potential, geomagnetic field, electromagnetic disturbance, and so on, I show the cases of the empirical prediction based on the observed electromagnetic data associated with some earthquakes in China. Finally, based on the above review, I propose an integrated research scheme of earthquake-related electromagnetic phenomena, which includes the interaction between appropriate observations, robust methodology of data processing, and theoretical model analysis. This study is supported partially by the National Natural Science Foundation of China (41274075) and the National Basic Research Program of China (2014CB845903).

  15. Synthesis and electro-magnetic properties of flower-like Fe2O3-Ag nanocomposite using direct subsidence loading method

    NASA Astrophysics Data System (ADS)

    Zhou, Xing; Wu, Zhengying; Xu, Nan; Liu, Shouqing; Zhao, Guizhe; Liu, Yaqing

    2015-10-01

    Novel flower-like Fe2O3/Ag nanocomposites were synthesized by a simple direct subsidence loading method. The composition and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SEAD) techniques. The Ag nanoparticles which loaded on the surface of petals exhibit spherical morphology. Further, the magnetic and electrical conductive properties reveal the well controllable performance. Room temperature magnetic measurement of the flower-like nanocomposites demonstrated its ferromagnetic properties and the saturation magnetization (Ms) decreased from 0.6 to 0.11 emu/g.

  16. Assessment of Electromagnetic Fields at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Ficklen, Carter B.

    1995-01-01

    This report presents the results of an assessment of ElectroMagnetic Fields (EMF) completed at NASA Langley Research Center as part of the Langley Aerospace Research Summer Scholars Program. This project was performed to determine levels of electromagnetic fields, determine the significance of the levels present, and determine a plan to reduce electromagnetic field exposure, if necessary. This report also describes the properties of electromagnetic fields and their interaction with humans. The results of three major occupational epidemiological studies is presented to determine risks posed to humans by EMF exposure. The data for this report came from peer-reviewed journal articles and government publications pertaining to the health effects of electromagnetic fields.

  17. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    PubMed Central

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-01-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

  18. High temperature electromagnetic characterization of thermal protection system tile materials

    NASA Technical Reports Server (NTRS)

    Heil, Garrett G.

    1993-01-01

    This study investigated the impact of elevated temperatures on the electromagnetic performance of the LI-2200 thermal protection system. A 15-kilowatt CO2 laser was used to heat an LI-2200 specimen to 3000 F while electromagnetic measurements were performed over the frequency range of l9 to 21 GHz. The electromagnetic measurement system consisted of two Dual-Lens Spot-Focusing (DLSF) antennas, a sample support structure, and an HP-8510B vector network analyzer. Calibration of the electromagnetic system was accomplished with a Transmission-Reflection-Line (TRL) procedure and was verified with measurements on a two-layer specimen of known properties. The results of testing indicated that the LI-2200 system's electromagnetic performance is slightly temperature dependent at temperatures up to 3000 F.

  19. Elastic metamaterials for tuning circular polarization of electromagnetic waves.

    PubMed

    Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

    2016-06-20

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  20. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-06-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  1. Superconducting dipole electromagnet

    DOEpatents

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  2. Improved Electromagnetic Brake

    NASA Technical Reports Server (NTRS)

    Martin, Toby B.

    2004-01-01

    A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may

  3. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  4. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  5. Electromagnetic probes of the QGP

    NASA Astrophysics Data System (ADS)

    Bratkovskaya, E. L.; Linnyk, O.; Cassing, W.

    2015-05-01

    We investigate the properties of the QCD matter across the deconfinement phase transition in the scope of the parton-hadron string dynamics (PHSD) transport approach. We present here in particular the results on the electromagnetic radiation, i.e. photon and dilepton production, in relativistic heavy-ion collisions. By comparing our calculations for the heavy-ion collisions to the available data, we determine the relative importance of the various production sources and address the possible origin of the observed strong elliptic flow v2 of direct photons. We argue that the different centrality dependence of the hadronic and partonic sources for direct photon production in nucleusnucleus collisions can be employed to shed some more light on the origin of the photon v2 "puzzle". While the dilepton spectra at low invariant mass show in-medium effects like an enhancement from multiple baryonic resonance formation or a collisional broadening of the vector meson spectral functions, the dilepton yield at high invariant masses (above 1.1 GeV) is dominated by QGP contributions for central heavy-ion collisions at ultra-relativistic energies. This allows to have an independent view on the parton dynamics via their electromagnetic massive radiation.

  6. Electromagnetic Transmission Through Resonant Structures

    NASA Astrophysics Data System (ADS)

    Young, Steven M.

    Electromagnetic resonators store energy in the form of oscillatory electric and magnetic fields and gradually exchange that energy by coupling with their environment. This coupling process can have profound effects on the transmission and reflection properties of nearby interfaces, with rapid transitions from high transmittance to high reflectance over narrow frequency ranges, and has been exploited to design useful optical components such as spectral filters and dielectric mirrors. This dissertation includes analytic, numeric, and experimental investigations of three different electromagnetic resonators, each based on a different method of confining electromagnetic fields near the region of interest. First, we show that a structure with two parallel conducting plates, each containing a subwavelength slit, supports a localized resonant mode bound to the slits and therefore exhibits (in the absence of nonradiative losses), perfect resonant transmission over a narrow frequency range. In practice, the transmission is limited by conduction losses in the sidewalls; nevertheless, experimental results at 10 GHz show a narrowband transmission enhancement by a factor of 104 compared to the non-resonant transmission, with quality factor (ratio of frequency to peak width) Q ~ 3000. Second, we describe a narrowband transmission filter based on a single-layer dielectric grating. We use a group theory analysis to show that, due to their symmetry, several of the grating modes cannot couple to light at normal incidence, while several others have extremely large coupling. We then show how selectively breaking the system symmetry using off-normal light incidence can produce transmission peaks by enabling weak coupling to some of the previously protected modes. The narrowband filtering capabilities are validated by an experimental demonstration in the long wavelength infrared, showing transmission peaks of quality factor Q ~ 100 within a free-spectral range of 8-15 mum. Third, we

  7. Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF

    NASA Astrophysics Data System (ADS)

    Sung, Zu-Hawn; Lee, Peter J.; Polyanskii, Anatolii; Balachandran, Shreyas; Chetri, Santosh; Larbalestier, David C.; Wang, Mingmin; Compton, Christopher; Bieler, Thomas R.

    2015-12-01

    High purity (RRR > 200), large grain (> 5-10 cm) niobium ingot slices have been successfully used to fabricate radio frequency (RF) cavities for particle accelerators. They offer significantly reduced fabrication cost by eliminating processing steps and furthermore they provide the opportunity to study the influence of individual grain boundaries in SRF Nb. Here we summarize our measurements of grain boundary (GB) effects on the superconducting properties of large grain high purity niobium sheet manufactured by CBMM. We show by magneto-optical (MO) imaging that GBs allow premature flux penetration, but only when they are oriented close to the direction of the magnetic field. However, even low angle GBs produced by minor deformations commensurate with half-cell forming produce localized flux penetration. The transport properties of grain boundaries were investigated by direct transport across them and evidence for preferential vortex flow along the GBs of SRF Nb was observed for the first time. Using transmission electron microscopy (TEM) and micro crystallographic analysis with electron backscattered diffraction (EBSD), we were able to quantitatively characterize surface substructures that can lead to localized thermal breakdown of superconductivity. Important to these studies was the development of sample preparation techniques that made the cutout single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.

  8. Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF

    SciTech Connect

    Sung, Zu-Hawn; Lee, Peter J. Polyanskii, Anatolii Balachandran, Shreyas Chetri, Santosh; Larbalestier, David C.

    2015-12-04

    High purity (RRR > 200), large grain (> 5-10 cm) niobium ingot slices have been successfully used to fabricate radio frequency (RF) cavities for particle accelerators. They offer significantly reduced fabrication cost by eliminating processing steps and furthermore they provide the opportunity to study the influence of individual grain boundaries in SRF Nb. Here we summarize our measurements of grain boundary (GB) effects on the superconducting properties of large grain high purity niobium sheet manufactured by CBMM. We show by magneto-optical (MO) imaging that GBs allow premature flux penetration, but only when they are oriented close to the direction of the magnetic field. However, even low angle GBs produced by minor deformations commensurate with half-cell forming produce localized flux penetration. The transport properties of grain boundaries were investigated by direct transport across them and evidence for preferential vortex flow along the GBs of SRF Nb was observed for the first time. Using transmission electron microscopy (TEM) and micro crystallographic analysis with electron backscattered diffraction (EBSD), we were able to quantitatively characterize surface substructures that can lead to localized thermal breakdown of superconductivity. Important to these studies was the development of sample preparation techniques that made the cutout single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.

  9. Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF

    DOE PAGES

    Sung, Zu -Hawn; Lee, Peter J.; Polyanskii, Anatolii; ...

    2015-12-04

    High purity (RRR > 200), large grain (> 5-10 cm) niobium ingot slices have been successfully used to fabricate radio frequency (RF) cavities for particle accelerators. In addition, they offer significantly reduced fabrication cost by eliminating processing steps and furthermore they provide the opportunity to study the influence of individual grain boundaries in SRF Nb. Here we summarize our measurements of grain boundary (GB) effects on the superconducting properties of large grain high purity niobium sheet manufactured by CBMM. We show by magneto-optical (MO) imaging that GBs allow premature flux penetration, but only when they are oriented close to themore » direction of the magnetic field. However, even low angle GBs produced by minor deformations commensurate with half-cell forming produce localized flux penetration. The transport properties of grain boundaries were investigated by direct transport across them and evidence for preferential vortex flow along the GBs of SRF Nb was observed for the first time. Using transmission electron microscopy (TEM) and micro crystallographic analysis with electron backscattered diffraction (EBSD), we were able to quantitatively characterize surface substructures that can lead to localized thermal breakdown of superconductivity. Important to these studies was the development of sample preparation techniques that made the cut-out single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.« less

  10. Large grain CBMM Nb ingot slices: An ideal test bed for exploring the microstructure-electromagnetic property relationships relevant to SRF

    SciTech Connect

    Sung, Zu -Hawn; Lee, Peter J.; Polyanskii, Anatolii; Balachandran, Shreyas; Chetri, Santosh; Larbalestier, David C.; Wang, Mingmin; Compton, Christopher; Bieler, Thomas R.

    2015-12-04

    High purity (RRR > 200), large grain (> 5-10 cm) niobium ingot slices have been successfully used to fabricate radio frequency (RF) cavities for particle accelerators. In addition, they offer significantly reduced fabrication cost by eliminating processing steps and furthermore they provide the opportunity to study the influence of individual grain boundaries in SRF Nb. Here we summarize our measurements of grain boundary (GB) effects on the superconducting properties of large grain high purity niobium sheet manufactured by CBMM. We show by magneto-optical (MO) imaging that GBs allow premature flux penetration, but only when they are oriented close to the direction of the magnetic field. However, even low angle GBs produced by minor deformations commensurate with half-cell forming produce localized flux penetration. The transport properties of grain boundaries were investigated by direct transport across them and evidence for preferential vortex flow along the GBs of SRF Nb was observed for the first time. Using transmission electron microscopy (TEM) and micro crystallographic analysis with electron backscattered diffraction (EBSD), we were able to quantitatively characterize surface substructures that can lead to localized thermal breakdown of superconductivity. Important to these studies was the development of sample preparation techniques that made the cut-out single, bi-crystal and tri-crystal Nb coupons as representative as possible of the surface properties of cavities manufactured by standard techniques.

  11. Electromagnetic radiation detector

    DOEpatents

    Benson, Jay L.; Hansen, Gordon J.

    1976-01-01

    An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

  12. Equivalence principles and electromagnetism

    NASA Technical Reports Server (NTRS)

    Ni, W.-T.

    1977-01-01

    The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

  13. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  14. Simple Superconducting "Permanent" Electromagnet

    NASA Technical Reports Server (NTRS)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  15. Optical electromagnetic radiation detector

    NASA Astrophysics Data System (ADS)

    Miceli, W. J.; Ludman, J. E.

    1985-08-01

    An optical electromagnetic radiation detector is invented having a probe for receiving nearby electromagnetic radiation. The probe includes a loop antenna connected to a pair of transparent electrodes deposited on the end surfaces of an electro-optic Fabry-Perot interferometer. When the loop antenna picks up the presence of electromagnetic radiation, a voltage will be developed across the crystal of the electro-optic Fabry-Perot interferometer thereby changing the optical length of the interferometer. A beam of light from a remote location is transmitted through an optical fiber onto the Fabry-Perot interferometer. The change in optical length of the Fabry-Perot interferometer alters the intensity of the beam of light as its is reflected from the Fabry-Perot interferometer back through the optical fiber to the remote location. A beamsplitter directs this reflected beam of light onto an intensity detector in order to provide an output indicative of the variations in intensity. The variations in intensity are directly related to the strength of the electromagnetic radiation received by the loop antenna.

  16. Nucleon electromagnetic form factors

    SciTech Connect

    Kees de Jager

    2000-01-01

    A review of data on the nucleon electromagnetic form factors in the space-like region is presented. Recent results from experiments using polarized beams and polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the data obtained with the traditional Rosenbluth separation. Future plans for extended measurements are outlined.

  17. Electromagnetic pulse bombs' defense

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wang, Yongbin; Li, Juan; Wang, Jianzhong

    2007-11-01

    With the high power microwave devices development, the high power microwave electromagnetic pulse bombs (E-bombs) have become practical abroad. The development of conventional E-bombs devices allows their use in nonnuclear confrontations. E-bombs are powerful enough to damage communication, radar, navigation and computer systems. This paper discusses effects of EMP on electrical system and how to defend the EMP.

  18. Computational Electronics and Electromagnetics

    SciTech Connect

    DeFord, J.F.

    1993-03-01

    The Computational Electronics and Electromagnetics thrust area is a focal point for computer modeling activities in electronics and electromagnetics in the Electronics Engineering Department of Lawrence Livermore National Laboratory (LLNL). Traditionally, they have focused their efforts in technical areas of importance to existing and developing LLNL programs, and this continues to form the basis for much of their research. A relatively new and increasingly important emphasis for the thrust area is the formation of partnerships with industry and the application of their simulation technology and expertise to the solution of problems faced by industry. The activities of the thrust area fall into three broad categories: (1) the development of theoretical and computational models of electronic and electromagnetic phenomena, (2) the development of useful and robust software tools based on these models, and (3) the application of these tools to programmatic and industrial problems. In FY-92, they worked on projects in all of the areas outlined above. The object of their work on numerical electromagnetic algorithms continues to be the improvement of time-domain algorithms for electromagnetic simulation on unstructured conforming grids. The thrust area is also investigating various technologies for conforming-grid mesh generation to simplify the application of their advanced field solvers to design problems involving complicated geometries. They are developing a major code suite based on the three-dimensional (3-D), conforming-grid, time-domain code DSI3D. They continue to maintain and distribute the 3-D, finite-difference time-domain (FDTD) code TSAR, which is installed at several dozen university, government, and industry sites.

  19. Electromagnetic Levitation: A Useful Tool in Microgravity Research

    NASA Technical Reports Server (NTRS)

    Szekely, Julian; Schwartz, Elliot; Hyers, Robert

    1995-01-01

    Electromagnetic levitation is one area of the electromagnetic processing of materials that has uses for both fundamental research and practical applications. This technique was successfully used on the Space Shuttle Columbia during the Spacelab IML-2 mission in July 1994 as a platform for accurately measuring the surface tensions of liquid metals and alloys. In this article, we discuss the key transport phenomena associated with electromagnetic levitation, the fundamental relationships associated with thermophysical property measurement that can be made using this technique, reasons for working in microgravity, and some of the results obtained from the microgravity experiments.

  20. Theory of electromagnetic fluctuations for magnetized multi-species plasmas

    SciTech Connect

    Navarro, Roberto E. Muñoz, Víctor; Araneda, Jaime; Moya, Pablo S.; Viñas, Adolfo F.; Valdivia, Juan A.

    2014-09-15

    Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians.

  1. Extremely Low Frequency Electromagnetic Investigation on Mars

    NASA Astrophysics Data System (ADS)

    Kozakiewicz, Joanna; Kulak, Andrzej; Kubisz, Jerzy; Zietara, Krzysztof

    2016-11-01

    Natural electromagnetic (EM) signals of extremely low frequencies (ELF, 3 Hz-3 kHz) can be used to study many of the electromagnetic processes and properties occurring in the Martian environment. Sources of these signals, related to electrical activity in the atmosphere, are very significant since they can influence radio wave propagation on the planet, the atmospheric composition, and the ionospheric structure. In addition, such EM signals can be employed in many purposes such as: surveying the subsurface of Mars or studying the impact of the space weather on the Martian ionosphere. As ELF waves propagate on very long distances, it is possible to explore properties of the entire planet using single-station recordings. In this study, we propose an experiment that allows measuring ELF signals from the Martian surface. Such measurements can be used for detection of electric discharges in the atmosphere and water reservoirs in the planetary subsurface.

  2. The van Cittert-Zernike theorem for electromagnetic fields.

    PubMed

    Ostrovsky, Andrey S; Martínez-Niconoff, Gabriel; Martínez-Vara, Patricia; Olvera-Santamaría, Miguel A

    2009-02-02

    The van Cittert-Zernike theorem, well known for the scalar optical fields, is generalized for the case of vector electromagnetic fields. The deduced theorem shows that the degree of coherence of the electromagnetic field produced by the completely incoherent vector source increases on propagation whereas the degree of polarization remains unchanged. The possible application of the deduced theorem is illustrated by an example of optical simulation of partially coherent and partially polarized secondary source with the controlled statistical properties.

  3. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; El-Sharawy, El-Budawy; Hashemi-Yeganeh, Shahrokh; Aberle, James T.; Birtcher, Craig R.

    1991-01-01

    The Advanced Helicopter Electromagnetics is centered on issues that advance technology related to helicopter electromagnetics. Progress was made on three major topics: composite materials; precipitation static corona discharge; and antenna technology. In composite materials, the research has focused on the measurements of their electrical properties, and the modeling of material discontinuities and their effect on the radiation pattern of antennas mounted on or near material surfaces. The electrical properties were used to model antenna performance when mounted on composite materials. Since helicopter platforms include several antenna systems at VHF and UHF bands, measuring techniques are being explored that can be used to measure the properties at these bands. The effort on corona discharge and precipitation static was directed toward the development of a new two dimensional Voltage Finite Difference Time Domain computer program. Results indicate the feasibility of using potentials for simulating electromagnetic problems in the cases where potentials become primary sources. In antenna technology the focus was on Polarization Diverse Conformal Microstrip Antennas, Cavity Backed Slot Antennas, and Varactor Tuned Circular Patch Antennas. Numerical codes were developed for the analysis of two probe fed rectangular and circular microstrip patch antennas fed by resistive and reactive power divider networks.

  4. ELECTROMAGNETIC RELEASE MECHANISM

    DOEpatents

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  5. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  6. Electromagnetic targeting of guns

    SciTech Connect

    Pogue, E.W.; Boat, R.M.; Holden, D.N.; Lopez, J.R.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.

  7. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1996-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  8. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1994-04-05

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

  9. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1994-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  10. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1996-06-11

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

  11. Proca and electromagnetic fields

    SciTech Connect

    Hillion, P.; Quinnerz, S.

    1986-07-01

    In the framework of the proper orthochronous Lorentz group, the old connection is revived between the electromagnetic field characterized by a self-dual tensor and a traceless second-rank spinor obeying the Proca equation. The relationship between this spinor and the Hertz potential also considered as a self-dual tensor is emphasized. The extension of this formalism to meet the covariance under the full Lorentz group is also discussed.

  12. Electromagnetic Hammer for Metalworking

    NASA Technical Reports Server (NTRS)

    Anderson, S. A.; Brunet, F.; Dowd, A.; Durham, R.; Ezell, J.; Gorr, G.; Hartley, D.; Jackson, F.; Marchand, J.; Macfarlane, W.; Nameth, P.; Okelly, K.; Phillips, H.; Rollo, J.; Rupert, E.; Sykes, H.; Vitrano, E.; Woods, M.

    1986-01-01

    High eddy currents apply pressure for cold-forming. Coil housing constructed for mechanical strength to hold coil against magnetic force, to maintain electrical contact with coil ends, and to maintain insulation between coil turns. Drilled holes placed to facilitate release of bubbles during potting. In contrast with mechanical hammers, electromagnetic hammer requires no dynamic material contact with workpiece; consequently, produces almost no change in metal grain structure.

  13. Modern Electromagnetic Scattering

    DTIC Science & Technology

    2013-08-10

    multiple thin coatings, J. Opt. Soc. Am. 37 (1947) 576–577. [11] F. Abelès, La théorie générale des couches minces, J. Phys. Radium 11 (1950) 307...Abelès, La théorie générale des couches minces, J. Phys. Radium 11 (1950) 307–310. [11] M. Born, E. Wolf, Principles of Optics: Electromagnetic Theory

  14. Ordinary electromagnetic mode instability

    NASA Technical Reports Server (NTRS)

    Cheng, C. Z.

    1974-01-01

    The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is studied for a single-species plasma with ring velocity distribution. The marginal instability boundaries for both the purely growing mode and the propagating growing modes are calculated from the instability criteria. The dispersion characteristics for various sets of plasma parameters are also given. The typical growth rates are of the order of the cyclotron frequency.

  15. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  16. High frequency electromagnetic properties of interstitial-atom-modified Ce{sub 2}Fe{sub 17}N{sub X} and its composites

    SciTech Connect

    Li, L. Z.; Wei, J. Z.; Xia, Y. H.; Wu, R.; Yun, C.; Yang, Y. B.; Yang, W. Y.; Du, H. L.; Han, J. Z.; Liu, S. Q.; Yang, Y. C.; Wang, C. S. E-mail: jbyang@pku.edu.cn; Yang, J. B. E-mail: jbyang@pku.edu.cn

    2014-07-14

    The magnetic and microwave absorption properties of the interstitial atom modified intermetallic compound Ce{sub 2}Fe{sub 17}N{sub X} have been investigated. The Ce{sub 2}Fe{sub 17}N{sub X} compound shows a planar anisotropy with saturation magnetization of 1088 kA/m at room temperature. The Ce{sub 2}Fe{sub 17}N{sub X} paraffin composite with a mass ratio of 1:1 exhibits a permeability of μ′ = 2.7 at low frequency, together with a reflection loss of −26 dB at 6.9 GHz with a thickness of 1.5 mm and −60 dB at 2.2 GHz with a thickness of 4.0 mm. It was found that this composite increases the Snoek limit and exhibits both high working frequency and permeability due to its high saturation magnetization and high ratio of the c-axis anisotropy field to the basal plane anisotropy field. Hence, it is possible that this composite can be used as a high-performance thin layer microwave absorber.

  17. Layering fabrication, structure, and electromagnetic properties of perovskite phases by hybrid process: self-propagated high-temperature synthesis and selective laser sintering

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.; Morozov, Yu.; Kuznetsov, M.

    2013-11-01

    The paper discusses the fundamentals and the requirements for layer-by-layer manufacturing of three-dimensional porous parts from complex metal oxide systems (piezoceramics PbTi1-xZrxO3; hexaferrites - BaFe12-xCrxO19 and SrFe12O19; spinels - Li0.5Fe2.5-xCrxO4 and high-temperature superconducting ceramics (HTSC) - YBa2Cu3O7-y) and examines the main aspects of the overlapped processes associated with the self-propagated high-temperature synthesis (SHS) and selective laser sintering (SLS). These two techniques presently offered are joined as the original solutions in this external magnetic field. The perovskite phase compositions, morphology, and element distribution of the fabricated samples were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped the EDX analysis. Optimal regimes for the three-dimensional (3D) parts laser synthesis and some of their electro physical properties were estimated for conducting the concurrent SHS-SLS reactions, both for the case with the applied dc magnetic field and without it.

  18. Nuclear Electromagnetic Pulse Review

    NASA Astrophysics Data System (ADS)

    Dinallo, Michael

    2011-04-01

    Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets - fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

  19. Carter separable electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Lynden-Bell, D.

    2000-02-01

    The purely electromagnetic analogue in flat space of Kerr's metric in general relativity is only rarely considered. Here we carry out in flat space a programme similar to Carter's investigation of metrics in general relativity in which the motion of a charged particle is separable. We concentrate on the separability of the motion (be it classical, relativistic or quantum) of a charged particle in electromagnetic fields that lie in planes through an axis of symmetry. In cylindrical polar coordinates (t,R,φ,z) the four-vector potential takes the form [formmu2] is the unit toroidal vector. The forms of the functions Φ(R,z) and A(R,z) are sought that allow separable motion. This occurs for relativistic motion only when AR,Φ and A2-Φ2 are all of the separable form ζ(λ)-η(μ)]/(λ-μ), where ζ and η are arbitrary functions, and λ and μ are spheroidal coordinates or degenerations thereof. The special forms of A and Φ that allow this are deduced. They include the Kerr metric analogue, with E+iB=-∇{q[(r-ia).(r-ia)]-1/2}. Rather more general electromagnetic fields allow separation when the motion is non-relativistic. The investigation is extended to fields that lie in parallel planes. Connections to Larmor's theorem are remarked upon.

  20. Estimating the power-law distribution of Earth electrical conductivity from low-frequency, controlled-source electromagnetic responses

    SciTech Connect

    Beskardes, G. D.; Weiss, Chester J.; Everett, M. E.

    2016-11-30

    Electromagnetic responses reflect the interaction between applied electromagnetic fields and heterogeneous geoelectrical structures. Here by quantifying the relationship between multi-scale electrical properties and the observed electromagnetic response is therefore important for meaningful geologic interpretation. Furthermore, we present here examples of near-surface electromagnetic responses whose spatial fluctuations appear on all length scales, are repeatable and fractally distributed, suggesting that the spatial fluctuations may be considered as “geologic noise”.

  1. Medium effect on the characteristics of the coupled seismic and electromagnetic signals.

    PubMed

    Huang, Qinghua; Ren, Hengxin; Zhang, Dan; Chen, Y John

    2015-01-01

    Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals.

  2. Coherent hybrid electromagnetic field imaging

    DOEpatents

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  3. Understanding Io's Interior Structure from Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Keszthelyi, L. P.; Jia, X.

    2015-12-01

    Io has long been suspected of a molten interior based on theoretical models of tidal dissipation in its interior. Extremely high temperature lava erupting on Io's surface would be consistent with an internal magma ocean but the highest reported eruption temperatures are questionable. Currently, the only direct evidence of a subsurface magma ocean in Io is the electromagnetic induction response observed by Galileo (Khurana et al. 2011, Science, 332, 1186). Using Jupiter's rotating magnetic field as a sounding signal, Khurana et al. (2011) provided evidence of a strong dipolar induction signature in Galileo's magnetometer data from four different flybys. They further showed that the signal is consistent with electromagnetic induction from large amounts of rock-melts in the asthenosphere of Io. Modeling showed that the induction response from a completely solid mantle model is inadequate to explain the magnetometer observations. However, a layer of asthenosphere >50 km in thickness with a melt fraction ≥20% is adequate to accurately match the observed magnetic field. Here we summarize our current knowledge of Io's interior from Galileo's induction measurements, and then outline a scheme to further infer properties of Io's interior, especially its internal temperature profile, by marrying the principles of thermodynamics with those of electromagnetism. In particular, we obtain guidance on stable mineral phases and their physical properties (such as density, melt state and electrical conductivity) from thermodynamic principles, whereas guidance on how the resulting internal conductivity profile affects the magnetic environment around Io is obtained from electromagnetic theory. We also explore how induction measurements can be obtained at multiple frequencies from a future mission and be used to constrain both the location and the thickness of the magma ocean. Finally, we explore the consequences of the global magma ocean on Io's physical properties such as the current

  4. Experiments for electromagnetic levitation in microgravity

    NASA Technical Reports Server (NTRS)

    Willnecker, R.; Egry, I.

    1990-01-01

    Containerless processing is a promising research tool for investigating the properties of undercooled melts and their solidification. For conducting samples RF-electromagnetic levitation offers the possibility to obtain large undercoolings by avoiding heterogeneous nucleation at container walls. On earth, however, strong magnetic fields are needed to compensate the gravitational force which imposes a lower limit on the available temperatures and on the accessible undercooling range. Under microgravity conditions the magnetic positioning fields can be minimized and hence, undercooling becomes feasible under ultra-high vacuum conditions and lower temperatures become accessible. In contrast to other undercooling and solidification techniques, electromagnetic levitation allows for diagnostic measurements during the early steps of nucleation and phase selection. Experiments cover a wide field of research topics: nucleation, directional solidification at high velocities, generation of metastable phases, evolution of microstructures, properties of undercooled liquids. Examples from these classes including experiments selected for the IML-2 mission are discussed with emphasis on technical requirements. An overview is given on the German TEMPUS (electromagnetic levitation facility) program.

  5. Optimization methods in control of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Angell, Thomas S.; Kleinman, Ralph E.

    1991-05-01

    This program is developing constructive methods for certain constrained optimization problems arising in the design and control of electromagnetic fields and in the identification of scattering objects. The problems addressed fall into three categories: (1) the design of antennas with optimal radiation characteristics measured in terms of directivity; (2) the control of the electromagnetic scattering characteristics of an object, in particular the minimization of its radar cross section, by the choice of material properties; and (3) the determination of the shape of scattering objects with various electromagnetic properties from scattered field data. The main thrust of the program is toward the development of constructive methods based on the use of complete families of solutions of the time-harmonic Maxwell equations in the infinite domain exterior to the radiating or scattering body. During the course of the work an increasing amount of attention has been devoted to the use of iterative methods for the solution of various direct and inverse problems. The continued investigation and development of these methods and their application in parameter identification has become a significant part of the program.

  6. Electromagnetic Meissner-Effect Launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1990-01-01

    Proposed electromagnetic Meissner-effect launching apparatus differs from previous electromagnetic launchers; no need for electromagnet coil on projectile. Result, no need for brush contacts and high-voltage commutation equipment to supply current directly to projectile coil, or for pulse circuitry to induce current in projectile coil if brush contacts not used. Compresses magnetic field surrounding rear surface of projectile, creating gradient of magnetic pressure pushing projectile forward.

  7. One-way electromagnetic waveguide using multiferroic Fibonacci superlattices

    NASA Astrophysics Data System (ADS)

    Tang, Zhenghua; Lei, Dajun; Huang, Jianquan; Jin, Gui; Qiu, Feng; Yan, Wenyan

    2015-12-01

    The multiferroic Fibonacci superlattices (MFSs) are composed of single-phase multiferroic domains with polarization and magnetization according to the rule of Fibonacci sequence. We propose to construct a one-way electromagnetic waveguide by the MFSs. The forbidden band structures of the MFSs for the forward and backward electromagnetic waves are not completely overlapped, and an obvious translation between them occurs around the fixed point ω bar = 1 with broken time-reversal and space inversion symmetries (TRSIS), which indicates the existence of one-way electromagnetic modes in the MFSs. Transmission spectrum is utilized to present this property and to indicate further one-way electromagnetic modes lying within the polaritonic band gap. The maximum forbidden bandwidth (divided by midgap frequency) of 5.4% for the backward electromagnetic wave (BEW) is found, in which the forward electromagnetic wave (FEW) can pass. The functions of one-way propagation modes and polaritonic band gap integrated into the MFSs can miniaturize the one-way photonic devices. The properties can also be applied to construct compact microwave isolators.

  8. Octet Baryon Electromagnetic Form Factors in a Relativistic Quark Model

    SciTech Connect

    Gilberto Ramalho, Kazuo Tsushima

    2011-09-01

    We study the octet baryon electromagnetic properties by applying the covariant spectator quark model, and provide covariant parametrization that can be used to study baryon electromagnetic reactions. While we use the lattice QCD data in the large pion mass regime (small pion cloud effects) to determine the parameters of the model in the valence quark sector, we use the nucleon physical and octet baryon magnetic moment data to parameterize the pion cloud contributions. The valence quark contributions for the octet baryon electromagnetic form factors are estimated by extrapolating the lattice parametrization in the large pion mass regime to the physical regime. As for the pion cloud contributions, we parameterize them in a covariant, phenomenological manner, combined with SU(3) symmetry. We also discuss the impact of the pion cloud effects on the octet baryon electromagnetic form factors and their radii.

  9. Shaping metallic glasses by electromagnetic pulsing

    PubMed Central

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-01-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

  10. Electromagnetic Heat Transfer in Artificial Materials

    NASA Astrophysics Data System (ADS)

    Woods, Lilia; Drosdoff, David; Phan, Anh

    2014-03-01

    Electromagnetic energy exchange has found promising new opportunities by greatly enhancing the heat transfer between bodies via radiation in the near-field regime. The greatest heat transfer occurs when the bodies support surface plasmons or polaritons that share the same resonant frequency. It has been shown, however, that 2-D materials such as graphene can have their surface plasmons tuned by modifying the chemical potential and temperature. This allows for tuning its resonance with other systems. In this talk, we investigated the electromagnetic radiation in metamaterials characterized by a strong magnetic response. We study theoretically Pendry-like and magnetically active metamaterial/graphene composites. The possibility for enhancing or inhibiting the heat transfer via the graphene properties is investigated.

  11. Shaping metallic glasses by electromagnetic pulsing

    NASA Astrophysics Data System (ADS)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-02-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  12. Shaping metallic glasses by electromagnetic pulsing.

    PubMed

    Kaltenboeck, Georg; Demetriou, Marios D; Roberts, Scott; Johnson, William L

    2016-02-08

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  13. Electromagnetic Meissner effect launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (Inventor)

    1991-01-01

    An electromagnetic projectile launcher provides acceleration of a superconducting projectile through the diamagnetic repulsion of the superconducting projectile. A superconducting layer is provided aft of the projectile, either directly on the projectile or on a platform upon which the projectile is carried, and a traveling magnetic field is caused to propagate along a magnetic field drive coil in which the projectile is disposed. The resulting diamagnetic repulsion between the superconducting projectile and the traveling magnetic field causes the projectile to be propelled along the coil. In one embodiment, a segmented drive coil is used to generate the traveling magnetic field.

  14. Electromagnetic strong plasma turbulence

    SciTech Connect

    Melatos, A.; Jenet, F. A.; Robinson, P. A.

    2007-02-15

    The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c{<=}v{<=}0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v{>=}0.1c to just free eigenstates for v{<=}0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

  15. Electromagnetic pump stator coil

    DOEpatents

    Fanning, Alan W.; Dahl, Leslie R.

    1996-01-01

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

  16. Electromagnetic pump stator coil

    DOEpatents

    Fanning, A.W.; Dahl, L.R.

    1996-06-25

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

  17. Advanced electromagnetic gun simulation

    NASA Astrophysics Data System (ADS)

    Brown, J. L.; George, E. B.; Lippert, J. R.; Balius, A. R.

    1986-11-01

    The architecture, software and application of a simulation system for evaluating electromagnetic gun (EMG) operability, maintainability, test data and performance tradeoffs are described. The system features a generic preprocessor designed for handling the large data rates necessary for EMG simulations. The preprocessor and postprocessor operate independent of the EMG simulation, which is viewed through windows by the user, who can then select the areas of the simulation desired. The simulation considers a homopolar generator, busbars, pulse shaping coils, the barrel, switches, and prime movers. In particular, account is taken of barrel loading by the magnetic field, Lorentz force and plasma pressure.

  18. Engineering electromagnetic metamaterials and methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Yen, Tajen

    2005-07-01

    Electromagnetic metamaterials represent a group of artificial structures, whose dimensions are smaller than subwavelength. Due to electromagnetic metamaterials' collective response to the applied fields, they can exhibit unprecedented properties to fascinate researchers' eyes. For instance, artificial magnetism above terahertz frequencies and beyond, negative magnetic response, and artificial plasma lower than ultraviolet and visible frequencies. Our goal is to engineer those novel properties aforementioned at interested frequency regions and further optimize their performance. To fulfill this task, we developed exclusive micro/nano fabrication techniques to construct magnetic metamaterials (i.e., split-ring resonators and L-shaped resonators) and electric metamaterials (i.e., plasmonic wires) and also employed Taguchi method to study the optimal design of electromagnetic metamaterials. Moreover, by integrating magnetic and electric metamaterials, we have been pursuing to fabricate so-called negative index media---the Holy Grail enables not only to reverse conventional optical rules such as Snell's law, Doppler shift, and Cerenkov radiation, but also to smash the diffraction limit to realize the superlensing effect. In addition to electromagnetic metamaterials, in this dissertation we also successfully miniaturize silicon-based methanol fuel cells by means of micro-electrical-mechanical-system technique, which promise to provide an integrated micro power source with excellent performance. Our demonstrated power density and energy density are one of the highest in reported documents. Finally, based on the results of metamaterials and micro fuel cells, we intend to supply building blocks to complete an omnipotent device---a system with sensing, communication, computing, power, control, and actuation functions.

  19. STRUCTURAL RESPONSE TO INTENSE ELECTROMAGNETIC RADIATION.

    DTIC Science & Technology

    EXPLODING WIRES, *GLASS, *DAMAGE, ELECTROMAGNETIC RADIATION , ENERGY CONVERSION, ENERGY CONVERSION, ELECTROMAGNETIC RADIATION , ELECTROMAGNETIC ... RADIATION , PLASTICS, PLASMAS(PHYSICS), STRESSES, THERMAL STRESSES, INSTRUMENTATION, ELECTRICAL RESISTANCE, ELECTRIC DISCHARGES, THERMOCOUPLES, MATHEMATICAL ANALYSIS, MATHEMATICAL ANALYSIS.

  20. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  1. Metamaterials beyond electromagnetism.

    PubMed

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  2. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  3. Electromagnetically driven liquid iris

    NASA Astrophysics Data System (ADS)

    Jang, Deasung; Jeong, Jin Won; Lee, Dae Young; Kim, Dae Geun; Chung, Sang Kug

    2016-11-01

    This paper describes a tunable liquid iris driven by electromagnetic actuation for miniature cameras. To examine the magnetic effect on a ferrofluid, the contact angle modification of a sessile ferrofluid droplet is tested using a neodymium magnet and an electric coil which 2.5 A current is applied to. The contact angle variations of the ferrofluid droplet for each test are 21.3 and 18.1 degrees, respectively. As a proof of concept, a pretest of a tunable iris actuated by electromagnetic effect is performed by using a hollow cylinder cell. As applying the current, the aperture diameter is adjusted from 4.06 mm at 0A to 3.21 mm at 2.0A. Finally, a tunable liquid iris (9 x 9 x 2 mm3) , consisting of two connected circular microchannels, is realized using MEMS technology. the aperture diameter of the tunable liquid iris is able to be modified from 1.72 mm at 0 A to 1.15 mm at 2.6 A. This tunable optical iris has potential applications not only for portable electronic devices but also in biomedical fields such as optical coherence tomography and microsurgery. This work was supported by 2016 Research Fund of Myongji University.

  4. Metamaterials beyond electromagnetism

    NASA Astrophysics Data System (ADS)

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  5. Electro-magnetic compatibility

    NASA Astrophysics Data System (ADS)

    Maidment, H.

    1980-05-01

    The historical background to the growth in problems of electromagnetic compatibility (EMC) in UK Military aircraft is reviewed and the present approach for minimizing these problems during development is discussed. The importance of using representative aircraft for final EMC assessments is stressed, and the methods of approach in planning and executing such tests are also outlined. The present equipment qualification procedures are based on assumptions regarding the electromagnetic fields present within the airframe, and the nature of the coupling mechanisms. These cannot be measured with any certainty in representative aircraft. Thus EMC assessments rely on practical tests. Avionics systems critical to flight safety, and systems vital to mission effectiveness require test methods that provide a measure of the safety and performance margins available to account for variations that occur in production and service use. Some proven methods are available, notably for detonator circuits, but in most other areas further work is required. Encouraging process has been made in the use of current probes for the measurement of interfering signals on critical signal lines, in conjunction with complementary test house procedures, as a means for obtaining the safety margins required in flight and engine control systems. Performance margins for mission systems using digital techniques are difficult to determine, and there is a need for improved test techniques. The present EMC qualification tests for equipment in the laboratory do not guarantee freedom from interference when installed, and the results are limited in value for correlating with aircraft tests.

  6. The HPS electromagnetic calorimeter

    DOE PAGES

    Balossino, I.; Baltzell, N.; Battaglieri, M.; ...

    2017-02-22

    The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called "heavy photon". Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015-2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. Finally, the detector is a homogeneous calorimeter, made of 442 lead-tungsten (PbWOmore » $$_4$$) scintillating crystals, each read-out by an avalanche photodiode coupled to a custom trans-impedance amplifier.« less

  7. Knots in electromagnetism

    NASA Astrophysics Data System (ADS)

    Arrayás, M.; Bouwmeester, D.; Trueba, J. L.

    2017-01-01

    Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless

  8. Electromagnetic Properties of Materials and Metamaterials

    DTIC Science & Technology

    2010-09-20

    39 3.2.2 Pri sm Coup ler...18 Figure 21 :NRI and Tefl on wedge-pri sms fabricated by Boeing for the DARPA...plasmon di spersion for a metal-air interface(dm) and, in the limit where the goes to zero, a metal-pri sm interface(pm) ........ ... ........ 40 Figure

  9. Project to Study Soil Electromagnetic Properties

    DTIC Science & Technology

    2007-09-30

    Thus, the instrument user must licence MatLab from MatWorks in order to run the spectrometer. For future systems , it is expected that it will be...possible to null the receiver system to any uniform spurious external magnetic field. Using a MATLAB program for the mutual coupling of thin wire loops...operating system and utilities then were installed. However, after MatLab and the UTEMIS system software had been installed, some erratic behaviour of the

  10. Electromagnetics laboratory annual report, 1994

    NASA Astrophysics Data System (ADS)

    Lindell, I. V.; Sihvola, A. H.

    1995-01-01

    Activities of the Electromagnetics Laboratory during 1994 are described in this report. As highlights of the output stand the monographs Electromagnetic Waves in Chiral and Bi-Isotropic Media (Artech House, Boston) and History of Electrical Engineering (Otatieto, Espoo, in Finnish). Also, the total number of papers published and accepted for publication in international refereed journals show a new record, 40 items.

  11. Exploration of the Electromagnetic Environment

    ERIC Educational Resources Information Center

    Fullekrug, M.

    2009-01-01

    The electromagnetic environment is composed of electric and magnetic fields which result from man-made and natural sources. An elementary experiment is described to explore the electromagnetic environment by measuring electric fields in the frequency range from approximately equal to 10 to 24 000 Hz. The equipment required to conduct the…

  12. SOME SPECULATIONS ON ELECTROMAGNETIC THEORY,

    DTIC Science & Technology

    An attempt is made to derive Maxwell’s equation of an Electromagnetic field, in vacuo, from the relativistic Liouville’s equation for the photon gas...intensity, while half of the difference of the two functions, divided by square root of (-1) is the magnetic field intensity. Two vector wave functions satisfy Maxwell’s equation of Electromagnetic wave in vacuo. (Author)

  13. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  14. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  15. Noninvasive Electromagnetic Detection of Bladder Cancer

    PubMed Central

    Cormio, Luigi; Vedruccio, Clarbruno; Leucci, Giorgio; Massenio, Paolo; Di Fino, Giuseppe; Cavaliere, Vincenzo; Carrieri, Giuseppe

    2014-01-01

    Objectives. Normal and neoplastic human tissues have different electromagnetic properties. This study aimed to determine the diagnostic accuracy of noninvasive electromagnetic detection of bladder cancer (BC) by the tissue-resonance interaction method (TRIM-prob). Patients and Methods. Consecutive patients were referred for cystoscopy because of (i) microscopic or gross hematuria and/or irritative voiding symptoms and (ii) bladder ultrasounds and urinary cytology findings negative or just suspicious of malignancy. Patients were first submitted to TRIM-prob bladder scanning by a single investigator and then to cystoscopy by another investigator blind to TRIM-prob data. Results. In 125 evaluated patients cystoscopy was positive for BC in 47 and negative in the remaining 78; conversely, TRIM-prob bladder scanning was positive for BC in 53 and negative in 72. In particular, TRIM-prob scanning yielded 7 false positives and only one false negative; therefore, its overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 97.9%, 89.9%, 86.8%, 98.6%, and 93.6%, respectively. Conclusions. TRIM-prob bladder scanning was a simple and quite accurate method for non-invasive electromagnetic detection of BC. If the elevated positive and negative predictive values will be replicated in further well-designed studies, it could be used to screen asymptomatic patients at high risk of BC. PMID:24563795

  16. Sensitivity analysis for electromagnetic topology optimization problems

    NASA Astrophysics Data System (ADS)

    Zhou, Shiwei; Li, Wei; Li, Qing

    2010-06-01

    This paper presents a level set based method to design the metal shape in electromagnetic field such that the incident current flow on the metal surface can be minimized or maximized. We represent the interface of the free space and conducting material (solid phase) by the zero-order contour of a higher dimensional level set function. Only the electrical component of the incident wave is considered in the current study and the distribution of the induced current flow on the metallic surface is governed by the electric field integral equation (EFIE). By minimizing or maximizing a costing function relative to the current flow, its distribution can be controlled to some extent. This method paves a new avenue to many electromagnetic applications such as antenna and metamaterial whose performance or properties are dominated by their surface current flow. The sensitivity of the objective function to the shape change, an integral formulation including both the solutions to the electric field integral equation and its adjoint equation, is obtained using a variational method and shape derivative. The advantages of the level set model lie in its flexibility of disposing complex topological changes and facilitating the mathematical expression of the electromagnetic configuration. Moreover, the level set model makes the optimization an elegant evolution process during which the volume of the metallic component keeps a constant while the free space/metal interface gradually approaching its optimal position. The effectiveness of this method is demonstrated through a self-adjoint 2D topology optimization example.

  17. Electromagnetically revolving sphere viscometer

    NASA Astrophysics Data System (ADS)

    Hosoda, Maiko; Sakai, Keiji

    2014-12-01

    In this paper, we propose a new method of low viscosity measurement, in which the rolling of a probe sphere on the flat solid bottom of a sample cell is driven remotely and the revolution speed of the probe in a sample liquid gives the viscosity measurements. The principle of this method is based on the electromagnetically spinning technique that we developed, and the method is effective especially for viscosity measurements at levels below 100 mPa·s with an accuracy higher than 1%. The probe motion is similar to that in the well-known rolling sphere (ball) method. However, our system enables a steady and continuous measurement of viscosity, which is problematic using the conventional method. We also discuss the limits of the measurable viscosity range common to rolling-sphere-type viscometers by considering the accelerating motion of a probe sphere due to gravity, and we demonstrate the performance of our methods.

  18. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi

    2007-10-01

    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.

  19. Electromagnetic scattering theory

    NASA Technical Reports Server (NTRS)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  20. Superconducting electromagnetic thruster

    SciTech Connect

    Meng, J.

    1993-02-11

    An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

  1. On steady electromagnetic equilibria

    NASA Astrophysics Data System (ADS)

    Lehnert, B.

    1986-12-01

    The existence of steady electromagnetic equilibrium states predicted by an extended Lorentz invariant formulation of Maxwell's equations is analyzed. General equilibrium solutions are outlined which lead to integrated field quantities of the system, such as total charge qo, magnetic moment Mo, mass mo and angular momentum so. The quantization of moMo/qo in terms of Bohr magnetons is shown to be equivalent to the proposed resonance condition of circulating self-confined radiation. Exact equilibrium solutions were deduced in two simple cases, thereby leading to a so of the same order as that of the electron, and to a qo one order of magnitude larger than the electronic charge. A variational procedure is suggested in search for states of minimum charge, under the subsidiary quantum conditions on moMo/qo and so, i.e., by varying the profile of the electric space charge distribution.

  2. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C. C.

    1997-02-01

    The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.

  3. Electromagnetic Gyrokinetic Simulations

    SciTech Connect

    Wan, W

    2003-11-19

    A new electromagnetic kinetic electron {delta} particle simulation model has been demonstrated to work well at large values of plasma {beta} times the ion-to-electron mass ratio. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfven wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. zonal fields are found to be very weak, consistent with theoretical predictions for {beta} below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.

  4. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT) have been developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters have been flown in space, though only PPTs have been used on operational satellites. The performance of operational PPTs is quite poor, providing only about 8 percent efficiency at about 1000 sec specific impulse. Laboratory PPTs yielding 34 percent efficiency at 5170 sec specific impulse have been demonstrated. Laboratory MPD thrusters have been demonstrated with up to 70 percent efficiency and 7000 sec specific impulse. Recent PIT performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 and 8000 sec.

  5. Electromagnetically Clean Solar Arrays

    NASA Technical Reports Server (NTRS)

    Stem, Theodore G.; Kenniston, Anthony E.

    2008-01-01

    The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the

  6. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1971-01-01

    Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

  7. Electromagnetic theory of optical coherence [Invited].

    PubMed

    Friberg, Ari T; Setälä, Tero

    2016-12-01

    The coherence theory of random, vector-valued optical fields has been of great research interest in recent years. In this work we formulate the foundations of electromagnetic coherence theory both in the space-time and space-frequency domains, with particular emphasis on various types of optical interferometry. Analyzing statistically stationary, two-component (paraxial) electric fields in the classical and quantum-optical contexts we show fundamental connections between the conventional (polarization) Stokes parameters and the associated two-point (coherence) Stokes parameters. Measurement of the coherence and polarization properties of random vector beams by nanoparticle scattering and two-photon absorption is also addressed.

  8. Material-independent modes for electromagnetic scattering

    NASA Astrophysics Data System (ADS)

    Forestiere, Carlo; Miano, Giovanni

    2016-11-01

    In this Rapid Communication, we introduce a representation of the electromagnetic field for the analysis and synthesis of the full-wave scattering by a homogeneous dielectric object of arbitrary shape in terms of a set of eigenmodes independent of its permittivity. The expansion coefficients are rational functions of the permittivity. This approach naturally highlights the role of plasmonic and photonic modes in any scattering process and suggests a straightforward methodology to design the permittivity of the object to pursue a prescribed tailoring of the scattered field. We discuss in depth the application of the proposed approach to the analysis and design of the scattering properties of a dielectric sphere.

  9. Giant field enhancement in electromagnetic Helmholtz nanoantenna

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Greffet, Jean-Jacques; Pelouard, Jean-Luc; Haïdar, Riad; Pardo, Fabrice

    2014-11-01

    Inspired by the acoustic Helmholtz resonator, we propose a slit-box electromagnetic nanoantenna able to concentrate the energy of an incident beam into surfaces a thousand times smaller than with a classical lens. This design produces a giant electric field enhancement throughout the slit. The intensity enhancement reaches 104 in the visible range up to 108 in the THz range even with focused beams, thanks to an omnidirectional reception. These properties could target applications requiring extreme light concentration, such as surface-enhanced infrared absorption, nonlinear optics, and biophotonics.

  10. Topics in curved- and flat-space electromagnetism

    SciTech Connect

    Mustafa, E.

    1987-01-01

    Several problems in curved-space and flat-space electromagnetism are discussed and resolved: use of the Hertz and Debye bivector potential schemes for the solution of Maxwell's equations for source-free electromagnetic test fields in general relativity is further developed. A new method for classifying such schemes is presented and the Debye schemes are given, for the first time, with respect to an orthonormal tetrad (basis). The electromagnetic properties of a slowly rotating charged thin shell (with charge density proportional to mass density) are considered in both curved and flat space. The g-factor g, magnetic moment and angular momentum of such a shell are computed as a function of the charge-to-mass and radius-to-mass ratios. The electromagnetic properties of the classical electron modeled as a thin charged shell are also considered. A solution to the problem that the energy and linear momentum of such an extended system do not transform properly under Lorentz transformations is given. An application of flat-space electromagnetism to pulsar astrophysics is given.

  11. The variation of the electromagnetic coupling and quintessence

    NASA Astrophysics Data System (ADS)

    Bento, M. C.; González Felipe, R.

    2009-04-01

    The properties of quintessence are examined through the study of the variation of the electromagnetic coupling. We consider two simple quintessence models with a modified exponential potential and study the parameter space constraints derived from the existing observational bounds on the variation of the fine structure constant and the most recent Wilkinson Microwave Anisotropy Probe observations.

  12. CUSB-II: a high precision electromagnetic spectrometer

    NASA Astrophysics Data System (ADS)

    Schamberger, R. D.; Heintz, U.; Lee-Franzini, J.; Lovelock, D. M. J.; Narain, M.; Willins, J.; Yanagisawa, C.; Tuts, P. M.; Franzini, P.; Kanekal, S.; Wu, Q. W.

    1991-11-01

    The design, construction and performance of a very compact precision electromagnetic spectrometer is described. The CUSB-II detector has been used to study ϒ spectroscopy, search for exotic particles and measure properties of the B and B ∗ mesons at the Cornell Electron Storage Ring.

  13. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Several court cases involving acquisition, use, and disposal of property by institutions of higher education are briefly summarized in this chapter. Cases discussed touch on such topics as municipal annexation of university property; repurchase of properties temporarily allocated to faculty members; implications of zoning laws and zoning board…

  14. Earthquake prediction with electromagnetic phenomena

    SciTech Connect

    Hayakawa, Masashi

    2016-02-01

    Short-term earthquake (EQ) prediction is defined as prospective prediction with the time scale of about one week, which is considered to be one of the most important and urgent topics for the human beings. If this short-term prediction is realized, casualty will be drastically reduced. Unlike the conventional seismic measurement, we proposed the use of electromagnetic phenomena as precursors to EQs in the prediction, and an extensive amount of progress has been achieved in the field of seismo-electromagnetics during the last two decades. This paper deals with the review on this short-term EQ prediction, including the impossibility myth of EQs prediction by seismometers, the reason why we are interested in electromagnetics, the history of seismo-electromagnetics, the ionospheric perturbation as the most promising candidate of EQ prediction, then the future of EQ predictology from two standpoints of a practical science and a pure science, and finally a brief summary.

  15. Conical electromagnetic radiation flux concentrator

    NASA Technical Reports Server (NTRS)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  16. Nonmagnetic metamaterial landscapes for guided electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Viaene, S.; Ginis, V.; Danckaert, J.; Tassin, P.

    2016-09-01

    Transformation optics provides a geometry-based tool to create new components taking advantage of artificial metamaterials with optical properties that are not available in nature. Unfortunately, although guided electromagnetic waves are crucial for optical circuitry, transformation optics is not yet compatible with two-dimensional slab waveguides. Indeed, after determining the propagation of confined waves along the waveguide with a two-dimensional coordinate transformation, the conventional application of transformation optics results in metamaterials whose properties are insensitive to the coordinate perpendicular to the waveguide, leading to bulky, and therefore impractical, designs. In this contribution, we formulate an alternative framework that leads to feasible coordinate-based designs of two-dimensional waveguides. To this end, we characterize a guided transverse-magnetic light mode by relevant electromagnetic equations: a Helmholtz equation to account for wave propagation and a dispersion relation to impose a continuous light profile at the interface. By considering how two-dimensional conformal transformations transform these equations, we are able to materialize the coordinate-designed flows with a nonmagnetic metamaterial core of varying thickness, obtaining a two-dimensional device. We numerically demonstrate the effectiveness and versatility of our equivalence relations with three crucial functionalities, a beam bender, a beam splitter and a conformal lens, on a qualitative and quantitative level, by respectively comparing the electromagnetic fields inside and the transmission of our two-dimensional metamaterial devices to that of their three-dimensional counterparts at telecom wavelengths. As a result, we envision that one coordinate-based multifunctional waveguide component may seamlessly split and bend light beams on the landscape of an optical chip.

  17. New Perspective on Classical Electromagnetism

    DTIC Science & Technology

    2013-04-01

    R. Feynman , R. Leighton, and M. Sands, The Feynman Lectures in Physics vol II (Addison-Wesley, Reading, MA, 1964). 6. W.K.H. Panofsky and M...of the basics of classical electromagnetism is provided by recognizing a previously overlooked law of induction as well as the physical reality of the...classical electromagnetism is provided by recognizing a previously overlooked law of induction as well as the physical reality of the vector potential

  18. Electromagnetic holographic imaging of bioimpedance

    NASA Astrophysics Data System (ADS)

    Smith, Dexter G.; Ko, Harvey W.; Lee, Benjamin R.; Partin, Alan W.

    1998-05-01

    The electromagnetic bioimpedance method has successfully measured the very subtle conductivity changes associated with brain edema and prostate tumor. This method provides noninvasive measurements using non-ionizing magnetic fields applied with a small coil that avoids the use of contact electrodes. This paper introduces results from combining a holographic signal processing algorithm and a low power coil system that helps provide the 3D image of impedance contrast that should make the noninvasive electromagnetic bioimpedance method useful in health care.

  19. Electromagnetic Counterparts to Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Kasliwal, Mansi M.; GROWTH Collaboration; iPTF/ZTF Collaboration

    2017-01-01

    The direct detection of gravitational waves from merging black holes marks the dawn of a new era. I will present ongoing efforts and prospectsto identify and characterize the electromagnetic counterpart. Among the various models for electromagnetic emission from binary neutronstar mergers, free neutron decay gives the most luminous and fast-evolving optical counterpart. I will describe a co-ordinated global effort, the GROWTH (Global Relay of Observatories Watching Transients Happen) network working in tandem with the Zwicky Transient Facility.

  20. Electromagnetic Launch to Space

    NASA Astrophysics Data System (ADS)

    McNab, I. R.

    Many advances in electromagnetic (EM) propulsion technology have occurred in recent years. Linear motor technology for low-velocity and high-mass applications is being developed for naval catapults. Such technology could serve as the basis for a first-stage booster launch--as suggested by the US National Aeronautics and Space Administration (NASA) in the Maglifter concept. Using railguns, laboratory experiments have demonstrated launch velocities of 2-3 km/s and muzzle energies > 8 MJ. The extension of this technology to the muzzle velocities ( 7500 m/s) and energies ( 10 GJ) needed for the direct launch of payloads into orbit is very challenging but may not be impossible. For launch to orbit, even long launchers (> 1000 m) would need to operate at accelerations > 1000 G to reach the required velocities, so it would only be possible to launch rugged payloads, such as fuel, water, and materiel. Interest is being shown in such concepts by US, European, Russian, and Chinese researchers. An intermediate step proposed in France could be to launch payloads to sounding rocket altitudes for ionospheric research.

  1. Electromagnetism of Bacterial Growth

    NASA Astrophysics Data System (ADS)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  2. Electromagnetically driven peristaltic pump

    DOEpatents

    Marshall, Douglas W.

    2000-01-01

    An electromagnetic peristaltic pump apparatus may comprise a main body section having an inlet end and an outlet end and a flexible membrane which divides the main body section into a first cavity and a second cavity. The first cavity is in fluid communication with the inlet and outlet ends of the main body section. The second cavity is not in fluid communication with the first cavity and contains an electrically conductive fluid. The second cavity includes a plurality of electrodes which are positioned within the second cavity generally adjacent the flexible membrane. A magnetic field generator produces a magnetic field having a plurality of flux lines at least some of which are contained within the second cavity of the main body section and which are oriented generally parallel to a flow direction in which a material flows between the inlet and outlet ends of the main body section. A control system selectively places a voltage potential across selected ones of the plurality of electrodes to deflect the flexible membrane in a wave-like manner to move material contained in the first cavity between the inlet and outlet ends of the main body section.

  3. Electromagnet Move Down William Floyd Parkway, 6/24/13

    SciTech Connect

    2013-06-24

    At midnight on Monday, June 24, 2013, a 50-foot-wide, circular electromagnet began the second leg of a 3,200-mile land and sea voyage from Brookhaven National Laboratory in New York to a new home at Fermilab in Illinois. There, scientists will use it to study the properties of muons, subatomic particles that live only 2.2 millionths of a second, and the results could open the door to new realms of particle physics. During this leg, Emmert International transported the electromagnet 10 miles down William Floyd Parkway to the Smith Point Marina, where it was loaded on a barge later in the day.

  4. Giant Electromagnet Move at Brookhaven Lab, June 22, 2013

    SciTech Connect

    2013-06-22

    On Saturday, June 22, 2013, a 50-foot-wide, circular electromagnet began its 3,200-mile land and sea voyage from Brookhaven National Laboratory in New York to a new home at Fermilab in Illinois. There, scientists will use it to study the properties of muons, subatomic particles that live only 2.2 millionths of a second, and the results could open the door to new realms of particle physics. In the first part of the move, Emmert International and a team of Fermilab and Brookhaven Lab scientists and engineers transported the electromagnet across the Brookhaven Lab site to a staging area by its main gate.

  5. Stored electromagnetic energy and quality factor of radiating structures

    PubMed Central

    Jelinek, Lukas; Vandenbosch, Guy A. E.

    2016-01-01

    This paper deals with the old yet unsolved problem of defining and evaluating the stored electromagnetic energy—a quantity essential for calculating the quality factor, which reflects the intrinsic bandwidth of the considered electromagnetic system. A novel paradigm is proposed to determine the stored energy in the time domain leading to the method, which exhibits positive semi-definiteness and coordinate independence, i.e. two key properties actually not met by the contemporary approaches. The proposed technique is compared with an up-to-date frequency domain method that is extensively used in practice. Both concepts are discussed and compared on the basis of examples of varying complexity. PMID:27274693

  6. [Applications of electromagnetic radiation in medicine].

    PubMed

    Miłowska, Katarzyna; Grabowska, Katarzyna; Gabryelak, Teresa

    2014-05-08

    Recent decades have been devoted to the intense search for the response to questions related to the impact of radiation on the human body. Due to the growing fashion for a healthy lifestyle, increasing numbers of works about the alleged dangers of electromagnetic waves and diseases that they cause appeared. However, the discoveries of 20th century, and knowledge of the properties of electromagnetic radiation have allowed to broaden the horizons of the use of artificial sources of radiation in many fields of science and especially in medicine. The aim of this paper is to show that although excessive radiation or high doses are dangerous to the human body, its careful and controlled use, does not pose a threat, and it is often necessary in therapy. The possibility of using ionizing radiation in radiotherapy, isotope diagnostics or medical imaging, and non-ionizing radiation in the treatment for dermatological disorders and cancers will be presented. The unique properties of synchrotron radiation result in using it on a large scale in the diagnosis of pathological states by imaging methods.

  7. Mapping permafrost with airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  8. Electromagnetic wave band structure due to surface plasmon resonances in a complex plasma

    NASA Astrophysics Data System (ADS)

    Vladimirov, S. V.; Ishihara, O.

    2016-07-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations can significantly modify plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The conditions necessary to observe the band-gap structure in laboratory dusty plasma and/or space (cosmic) dusty plasmas are discussed.

  9. Non-local Optical Topological Transitions and Critical States in Electromagnetic Metamaterials

    PubMed Central

    Ishii, Satoshi; Narimanov, Evgenii

    2015-01-01

    Just as the topology of the Fermi surface defines the properties of the free electrons in metals and semiconductors, the geometry of the iso-frequency surface in the phase space of the propagating electromagnetic waves, determines the optical properties of the corresponding optical materials. Furthermore, in the direct analog to the Lifshitz transition in condensed matter physics, a change in the topology of iso-frequency surface has a dramatic effect on the emission, propagation and scattering of the electromagnetic waves. Here, we uncover a new class of such optical topological transitions in metamaterials, induced by the non-locality of the electromagnetic response inherent to these composites. PMID:26670600

  10. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, Ki H.; Xie, Gan Q.

    1994-01-01

    A method for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The traveltimes corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter .alpha. for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography.

  11. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, K.H.; Xie, G.Q.

    1994-12-13

    A method is described for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The travel times corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter [alpha] for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography. 13 figures.

  12. Development oF High Frequency Electromagnetic Mapping (HFEM) technology

    NASA Astrophysics Data System (ADS)

    Jesch, R. L.

    1982-04-01

    High frequency electromagnetic mapping (HFEM) techniques were developed for evaluating rubblized oil shale in the cold retort state in the modified in situ process. This technology development is also applicable for using HFEM techniques for diagnosing, monitoring, controlling and evaluating modified in situ retorts after they are ignited. The baseline data work required to design a high temperature sample holder and experiments for determining the EM properties of oil shale samples at elevated temperatures (200 to 500 C) are described. A theoretical approach is given for modeling oil shale retorts for electromagnetic sensing techniques by a spheroid with an average dielectric constant along with numerical results. Finally, the measurement results are given for the spent and raw shale samples that were obtained from portions of the ten half score samples plus the results of the electromagnetic transmission measurements taken on oil shale samples.

  13. Novel Planar Electromagnetic Sensors: Modeling and Performance Evaluation

    PubMed Central

    Mukhopadhyay, Subhas C.

    2005-01-01

    High performance planar electromagnetic sensors, their modeling and a few applications have been reported in this paper. The researches employing planar type electromagnetic sensors have started quite a few years back with the initial emphasis on the inspection of defects on printed circuit board. The use of the planar type sensing system has been extended for the evaluation of near-surface material properties such as conductivity, permittivity, permeability etc and can also be used for the inspection of defects in the near-surface of materials. Recently the sensor has been used for the inspection of quality of saxophone reeds and dairy products. The electromagnetic responses of planar interdigital sensors with pork meats have been investigated.

  14. Electromagnetic safety of children using wireless phones: a literature review.

    PubMed

    Martens, Luc

    2005-01-01

    In this article, several issues related to the safety of electromagnetic field exposure of children when using wireless devices such as mobile phones are described. The information available in the literature is reviewed and open areas that need to be subject of future research are identified. A lack of proof that dielectric properties change with age and an inconsistency in absorption studies in children is reported. The number of biological studies relevant to children is limited. Only some of the cognitive studies specifically target children and these show no significant effect of exposure. There is also a need to investigate the impact of electromagnetic fields on the developmental process of children. All this makes a definitive answer to the question if children are more sensitive to electromagnetic fields than adults impossible. More consistent research will be needed. This study is part of the European COST281 project "Potential Health Implications from Mobile Communication Systems."

  15. Surface electromagnetic wave equations in a warm magnetized quantum plasma

    SciTech Connect

    Li, Chunhua; Yang, Weihong; Wu, Zhengwei; Chu, Paul K.

    2014-07-15

    Based on the single-fluid plasma model, a theoretical investigation of surface electromagnetic waves in a warm quantum magnetized inhomogeneous plasma is presented. The surface electromagnetic waves are assumed to propagate on the plane between a vacuum and a warm quantum magnetized plasma. The quantum magnetohydrodynamic model includes quantum diffraction effect (Bohm potential), and quantum statistical pressure is used to derive the new dispersion relation of surface electromagnetic waves. And the general dispersion relation is analyzed in some special cases of interest. It is shown that surface plasma oscillations can be propagated due to quantum effects, and the propagation velocity is enhanced. Furthermore, the external magnetic field has a significant effect on surface wave's dispersion equation. Our work should be of a useful tool for investigating the physical characteristic of surface waves and physical properties of the bounded quantum plasmas.

  16. Metamaterial with electromagnetic transparency under multiband absorptions

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Qi, Limei

    2017-02-01

    We propose a metal-dielectric-metal (MDM) metamaterial that has an electromagnetic (EM) transparency spectrum under multiband absorptions in the C and the X bands. The ground continuous metal film used in the conventional metamaterial absorber (MA) is replaced by a structured ground plane (SGP) in our design. The band-pass properties of the front patterned metal film and the SGP determine the EM transparency spectrum, while the magnetic and the electric resonances in the MDM structure contribute to the multiband absorptions. Due to the symmetric structure of the unit cell, the absorption bands and the EM transparency spectrum of the metamaterial have the property of polarization independency. Despite the normal incidence, the metamaterial can also be used for non-normal incidence.

  17. Novel electromagnetic micropump

    NASA Astrophysics Data System (ADS)

    Feldmann, M.; Demming, S.; Lesche, C.; Büttgenbach, S.

    2007-12-01

    The mergence of partial aspects and functional components of micro actuators and micro fluidic technology allows the development of complex micro systems, which are more and more interesting for MEMS application, especially for BioMEMS. This enormous potential is shown in this article showing the realization of an electro magnetic micro pump. The basic build-up consists of a polymer magnet integrated into a pump chamber of a fluidic PDMS device, which is located above a double layer micro coil. By applying a current, the polymer magnet performs a bidirectional movement, which results in a pumping effect by the two arranged passive check valves being perpendicularly arranged to the flow channels. The valve membrane is flexible and opens the channel towards the flow direction. The advantage of this configuration is that leakage can be avoided by the special geometrical configuration of the fluid chamber and the valves. The fabrication process includes UV depth lithography using AZ9260, electroforming of copper for the double layer spiral coil and Epon SU-8 for insulation, embedding and manufacturing of the valve seat. Furthermore, the fluidic devices are realized by replica molding of PDMS using a multilayer SU-8 master. Furthermore, a new technology for realizing micro polymer magnets was optimized and deployed. Using these fabrication processes, a magnetic micro actuator has already been developed based on the movable plunger principle, which forms the basic set-up of the micro pump. This actuator is monolithically fabricated and successfully tested. In addition, the fluidic system of the micro pump was successfully fabricated and tested. In order to connect the valve seats based on SU-8 to the PDMS fluidic chamber and the valve lips, a special bonding process was developed. The combination of the fluidic system with the electromagnetic part is currently under investigation. The dimension of the micro pump is about 10 × 6 × 3 mm.

  18. Megawatt Electromagnetic Plasma Propulsion

    NASA Technical Reports Server (NTRS)

    Gilland, James; Lapointe, Michael; Mikellides, Pavlos

    2003-01-01

    The NASA Glenn Research Center program in megawatt level electric propulsion is centered on electromagnetic acceleration of quasi-neutral plasmas. Specific concepts currently being examined are the Magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). In the case of the MPD thruster, a multifaceted approach of experiments, computational modeling, and systems-level models of self field MPD thrusters is underway. The MPD thruster experimental research consists of a 1-10 MWe, 2 ms pulse-forming-network, a vacuum chamber with two 32 diffusion pumps, and voltage, current, mass flow rate, and thrust stand diagnostics. Current focus is on obtaining repeatable thrust measurements of a Princeton Benchmark type self field thruster operating at 0.5-1 gls of argon. Operation with hydrogen is the ultimate goal to realize the increased efficiency anticipated using the lighter gas. Computational modeling is done using the MACH2 MHD code, which can include real gas effects for propellants of interest to MPD operation. The MACH2 code has been benchmarked against other MPD thruster data, and has been used to create a point design for a 3000 second specific impulse (Isp) MPD thruster. This design is awaiting testing in the experimental facility. For the PIT, a computational investigation using MACH2 has been initiated, with experiments awaiting further funding. Although the calculated results have been found to be sensitive to the initial ionization assumptions, recent results have agreed well with experimental data. Finally, a systems level self-field MPD thruster model has been developed that allows for a mission planner or system designer to input Isp and power level into the model equations and obtain values for efficiency, mass flow rate, and input current and voltage. This model emphasizes algebraic simplicity to allow its incorporation into larger trajectory or system optimization codes. The systems level approach will be extended to the pulsed inductive

  19. Property.

    ERIC Educational Resources Information Center

    Goldblatt, Steven M.; Piele, Philip K.

    This chapter reviews 1982 cases related to school property. Cases involving citizen efforts to overturn school board decisions to close schools dominate the property chapter, and courts continue to uphold school board authority to close schools, transfer students, and sell or lease the buildings. Ten cases involving detachment and attachment of…

  20. Property.

    ERIC Educational Resources Information Center

    Bickel, Robert D.; Zeller, Trisha A.

    A number of cases related to property issues involving institutions of higher education are examined in this chapter. Cases discussed touch on such topics as funding for property and equipment acquisition; opposition to building construction or demolition; zoning issues; building construction and equipment contracts; and lease agreements. Current…

  1. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Johnson, Margaret M.

    This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state could…

  2. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Chapter 7 of a book on school law, this chapter deals with 1979 cases involving disputes over property. Cases involving taxpayer attempts to prevent the construction of school buildings dominate this year's property chapter, as they did last year's. Yet, paradoxically, there is also a significant increase in cases in which taxpayers tried to…

  3. Information Security due to Electromagnetic Environments

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Hidenori; Seto, Shinji

    Generally, active electronic devices emit slightly unintentional electromagnetic noise. From long ago, electromagnetic emission levels have been regulated from the aspect of electromagnetic compatibility (EMC). Also, it has been known the electromagnetic emissions have been generated from the ON/OFF of signals in the device. Recently, it becomes a topic of conversation on the information security that the ON/OFF on a desired signal in the device can be reproduced or guessed by receiving the electromagnetic emission. For an example, a display image on a personal computer (PC) can be reconstructed by receiving and analyzing the electromagnetic emission. In sum, this fact makes known information leakage due to electromagnetic emission. “TEMPEST" that has been known as a code name originated in the U. S. Department of Defense is to prevent the information leakage caused by electromagnetic emissions. This paper reports the brief summary of the information security due to electromagnetic emissions from information technology equipments.

  4. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    NASA Astrophysics Data System (ADS)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2015-09-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  5. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    PubMed Central

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-01-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet–height and diameter– and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials. PMID:26354891

  6. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets.

    PubMed

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-09-10

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  7. Non-dissipative electromagnetic media with two Lorentz null cones

    SciTech Connect

    Dahl, Matias F.

    2013-03-15

    We study Maxwell's equations on a 4-manifold where the electromagnetic medium is modeled by an antisymmetric (2/2 )-tensor with 21 real coefficients. In this setting the Fresnel surface is a fourth-order polynomial surface that describes the dynamical response of the medium in the geometric optics limit. For example, in an isotropic medium the Fresnel surface is a Lorentz null cone. The contribution of this paper is the pointwise description of all electromagnetic medium tensors {kappa} with real coefficients that satisfy the following three conditions: (i)medium {kappa} is invertible, (ii)medium {kappa} is skewon-free, or non-dissipative, (iii)the Fresnel surface of {kappa} is the union of two distinct Lorentz null cones. We show that there are only three classes of media with these properties and give explicit expressions in local coordinates for each class. - Highlights: Black-Right-Pointing-Pointer We find two new electromagnetic media classes for which the Fresnel surface decomposes into two light cones. Black-Right-Pointing-Pointer In a suitable setting we classify all electromagnetic media where this is the case. Black-Right-Pointing-Pointer We find an electromagnetic medium tensor with three different signal speeds in one direction. Black-Right-Pointing-Pointer The work is related to [5], which classifies all media with one light cone (in a suitable setting).

  8. Un-renormalized classical electromagnetism

    SciTech Connect

    Ibison, Michael . E-mail: ibison@earthtech.org

    2006-02-15

    This paper follows in the tradition of direct-action versions of electromagnetism having the aim of avoiding a balance of infinities wherein a mechanical mass offsets an infinite electromagnetic mass so as to arrive at a finite observed value. However, the direct-action approach ultimately failed in that respect because its initial exclusion of self-action was later found to be untenable in the relativistic domain. Pursing the same end, this paper examines instead a version of electromagnetism wherein mechanical action is excluded and self-action is retained. It is shown that the resulting theory is effectively interacting due to the presence of infinite forces. A vehicle for the investigation is a pair of classical point charges in a positronium-like arrangement for which the orbits are found to be self-sustaining and naturally quantized.

  9. Electron microscopy of electromagnetic waveforms

    NASA Astrophysics Data System (ADS)

    Ryabov, A.; Baum, P.

    2016-07-01

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample’s oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available.

  10. Electromagnetic fields and public health.

    PubMed Central

    Aldrich, T E; Easterly, C E

    1987-01-01

    A review of the literature is provided for the topic of health-related research and power frequency electromagnetic fields. Minimal evidence for concern is present on the basis of animal and plant research. General observation would accord with the implication that there is no single and manifest health effect as the result of exposure to these fields. There are persistent indications, however, that these fields have biologic activity, and consequently, there may be a deleterious component to their action, possibly in the presence of other factors. Power frequency electromagnetic field exposures are essentially ubiquitous in modern society, and their implications in the larger perspective of public health are unclear at this time. Electromagnetic fields represent a methodological obstacle for epidemiologic studies and a quandary for risk assessment; there is need for more data. PMID:3319560

  11. Electromagnetic Gun With Commutated Coils

    NASA Technical Reports Server (NTRS)

    Elliott, David G.

    1991-01-01

    Proposed electromagnetic gun includes electromagnet coil, turns of which commutated in sequence along barrel. Electrical current fed to two armatures by brushes sliding on bus bars in barrel. Interaction between armature currents and magnetic field from coil produces force accelerating armature, which in turn, pushes on projectile. Commutation scheme chosen so magnetic field approximately coincides and moves with cylindrical region defined by armatures. Scheme has disadvantage of complexity, but in return, enables designer to increase driving magnetic field without increasing armature current. Attainable muzzle velocity increased substantially.

  12. Electromagnetic suspension and levitation techniques

    NASA Astrophysics Data System (ADS)

    Jayawant, B. V.

    1988-04-01

    A comprehensive account is given of state-of-the-art and prospective electromagnetic and electromechanical suspension/levitation technologies, using both conventional and superconducting materials, with a view both to their performance improvements over differently grounded technologies and their economic feasibility. In addition to passenger-carrying vehicles, controlled DC electromagnet technologies have been applied to frictionless magnetic bearings, flow meters, conveyor systems, high-speed machine tool spindles, ultracentrifuges, turboalternators, corrosive-liquid pumps, gas compressors, high-vacuum pumps, and energy storage flywheels. Attention is given to the commercial prospects for devices based on superconducting magnets.

  13. Bathymetry, electromagnetic streamlines and the marine controlled source electromagnetic method

    NASA Astrophysics Data System (ADS)

    Pethick, Andrew 12Harris, Brett

    2014-07-01

    Seafloor topography must influence the strength and direction of electromagnetic fields generated during deep ocean controlled source electromagnetic surveying. Neither mathematical equation nor rules of thumb provide a clear perspective of how changes in water column thickness alters electromagnetic fields that engulf hundreds of cubic kilometres of air, ocean, host and reservoir. We use streamline visualisation to provide a generalised representation of how electromagnetic fields propagate into a 2D geo-electrical setting that includes strong bathymetry. Of particular interest are: (i)' dead zones' where electric fields at the ocean floor are demonstrated to be weak and (ii) the 'airwave' that appears in the electric field streamlines as circulating vortices with a shape that is clearly influenced by changes in ocean depth. Our analysis of the distribution of electric fields for deep and shallow water examples alludes to potential benefits from placement of receivers and/or transmitters higher in the water column as is the case for towed receiver geometries. Real-time streamline representation probably holds the most value at the survey planning stage, especially for shallow water marine EM surveys where ocean bottom topography is likely to be consequential.

  14. From the electromagnetic pulse to high-power electromagnetics

    NASA Astrophysics Data System (ADS)

    Baum, Carl E.

    1992-06-01

    This paper updates the published literature of the late 1970's concerning the development of requisite technology for the nuclear EMP. EMP has impacted a set of related areas that can be collectively referred to as high-power electromagnetics. This includes high-power microwaves, direct-strike lightning, and some aspects of transient radar.

  15. Electromagnetic excitation of the Delta(1232) resonance

    SciTech Connect

    V. Pascalutsa; M. Vanderhaeghen; Shin Nan Yang

    2006-09-05

    We review the description of the lowest-energy nucleon excitation--the Delta(1232)-resonance. Much of the recent effort has been focused on the precision measurements of the nucleon to Delta transition by means of electromagnetic probes. We review the results of those measurements and confront them with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice QCD, and QCD-inspired models. Some of the theoretical approaches are reviewed in detail. In particular, we describe the chiral EFT of QCD in the energy domain of the Delta-resonance, and its applications to the electromagnetic nucleon-to-Delta transition (gamma N Delta). We also describe the recent dynamical and unitary-isobar models of pion electroproduction which are extensively used in the extraction of the gamma* N Delta form factors from experiment. Furthermore, we discuss the link of the gamma* N Delta form factors to generalized parton distributions (GPDs), as well as the predictions of perturbative QCD for these transition form factors. The present status of understanding the Delta-resonance properties and the nature of its excitation is summarized.

  16. Electromagnetic exploration of the oceanic mantle

    PubMed Central

    UTADA, Hisashi

    2015-01-01

    Electromagnetic exploration is a geophysical method for examining the Earth’s interior through observations of natural or artificial electromagnetic field fluctuations. The method has been in practice for more than 70 years, and 40 years ago it was first applied to ocean areas. During the past few decades, there has been noticeable progress in the methods of instrumentation, data acquisition (observation), data processing and inversion. Due to this progress, applications of this method to oceanic regions have revealed electrical features of the oceanic upper mantle down to depths of several hundred kilometers for different geologic and tectonic environments such as areas around mid-oceanic ridges, areas around hot-spot volcanoes, subduction zones, and normal ocean areas between mid-oceanic ridges and subduction zones. All these results estimate the distribution of the electrical conductivity in the oceanic mantle, which is key for understanding the dynamics and evolution of the Earth together with different physical properties obtained through other geophysical methods such as seismological techniques. PMID:26062736

  17. Electromagnetic exploration of the oceanic mantle.

    PubMed

    Utada, Hisashi

    2015-01-01

    Electromagnetic exploration is a geophysical method for examining the Earth's interior through observations of natural or artificial electromagnetic field fluctuations. The method has been in practice for more than 70 years, and 40 years ago it was first applied to ocean areas. During the past few decades, there has been noticeable progress in the methods of instrumentation, data acquisition (observation), data processing and inversion. Due to this progress, applications of this method to oceanic regions have revealed electrical features of the oceanic upper mantle down to depths of several hundred kilometers for different geologic and tectonic environments such as areas around mid-oceanic ridges, areas around hot-spot volcanoes, subduction zones, and normal ocean areas between mid-oceanic ridges and subduction zones. All these results estimate the distribution of the electrical conductivity in the oceanic mantle, which is key for understanding the dynamics and evolution of the Earth together with different physical properties obtained through other geophysical methods such as seismological techniques.

  18. Spatially variant periodic structures in electromagnetics

    PubMed Central

    Rumpf, Raymond C.; Pazos, Javier J.; Digaum, Jennefir L.; Kuebler, Stephen M.

    2015-01-01

    Spatial transforms are a popular technique for designing periodic structures that are macroscopically inhomogeneous. The structures are often required to be anisotropic, provide a magnetic response, and to have extreme values for the constitutive parameters in Maxwell's equations. Metamaterials and photonic crystals are capable of providing these, although sometimes only approximately. The problem still remains about how to generate the geometry of the final lattice when it is functionally graded, or spatially varied. This paper describes a simple numerical technique to spatially vary any periodic structure while minimizing deformations to the unit cells that would weaken or destroy the electromagnetic properties. New developments in this algorithm are disclosed that increase efficiency, improve the quality of the lattices and provide the ability to design aplanatic metasurfaces. The ability to spatially vary a lattice in this manner enables new design paradigms that are not possible using spatial transforms, three of which are discussed here. First, spatially variant self-collimating photonic crystals are shown to flow unguided waves around very tight bends using ordinary materials with low refractive index. Second, multi-mode waveguides in spatially variant band gap materials are shown to guide waves around bends without mixing power between the modes. Third, spatially variant anisotropic materials are shown to sculpt the near-field around electric components. This can be used to improve electromagnetic compatibility between components in close proximity. PMID:26217058

  19. ORDNANCE CORPS VIEWS ELECTROMAGNETIC RADIATION HAZARDS TO WEAPONS SYSTEMS,

    DTIC Science & Technology

    EXPLOSIVES INITIATORS, * ELECTROMAGNETIC RADIATION ), HAZARDS, ELECTROMAGNETIC SHIELDING, RADIOFREQUENCY POWER, ANTENNAS, ATTENUATORS, IMPEDANCE MATCHING, SENSITIVITY, WEAPON SYSTEMS, MODULATION, CIRCUITS, BROADBAND

  20. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields.

    PubMed

    Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo

    2011-01-01

    Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields.

  1. Electromagnetic radiation as a probe of the initial state and of viscous dynamics in relativistic nuclear collisions

    NASA Astrophysics Data System (ADS)

    Vujanovic, Gojko; Paquet, Jean-François; Denicol, Gabriel S.; Luzum, Matthew; Jeon, Sangyong; Gale, Charles

    2016-07-01

    The penetrating nature of electromagnetic signals makes them suitable probes to explore the properties of the strongly interacting medium created in relativistic nuclear collisions. We examine the effects of the initial conditions and shear relaxation time on the spectra and flow coefficients of electromagnetic probes, using an event-by-event 3+1-dimensional viscous hydrodynamic simulation (music).

  2. Some Student Conceptions of Electromagnetic Induction

    ERIC Educational Resources Information Center

    Thong, Wai Meng; Gunstone, Richard

    2008-01-01

    Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students' conceptions of electromagnetism, to investigate to what extent the results from the present…

  3. Handheld Broadband Electromagnetic UXO Sensor

    DTIC Science & Technology

    2006-12-01

    OMB control number. 1. REPORT DATE DEC 2006 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Handheld Broadband Electromagnetic...SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release , distribution unlimited 13. SUPPLEMENTARY...6 2.1.2.1 Response Stage Algorithms ....................................................... 6 2.1.2.2 Discrimination Stage Algorithms

  4. Electromagnetic calorimeter for Belle II

    NASA Astrophysics Data System (ADS)

    Belle-ECL; Aulchenko, V.; Bobrov, A.; Bondar, A.; Cheon, B. G.; Eidelman, S.; Epifanov, D.; Garmash, Yu; Goh, Y. M.; Kim, S. H.; Krokovny, P.; Kuzmin, A.; Lee, I. S.; Matvienko, D.; Miyabayashi, K.; Nakamura, I.; Shebalin, V.; Shwartz, B.; Unno, Y.; Usov, Yu; Vinokurova, A.; Vorobjev, V.; Zhilich, V.; Zhulanov, V.

    2015-02-01

    The electromagnetic calorimeter of the BELLE II detector for experiments at Super B-factory SuperKEKB is briefly described. The project of the calorimeter upgrade to meet severe background conditions expected at the upgraded KEK B factory is presented.

  5. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  6. Electromagnetic pulses bone healing booster

    NASA Astrophysics Data System (ADS)

    Sintea, S. R.; Pomazan, V. M.; Bica, D.; Grebenisan, D.; Bordea, N.

    2015-11-01

    Posttraumatic bone restoration triggered by the need to assist and stimulate compensatory bone growth in periodontal condition. Recent studies state that specific electromagnetic stimulation can boost the bone restoration, reaching up to 30% decrease in recovery time. Based on the existing data on the electromagnetic parameters, a digital electronic device is proposed for intra oral mounting and bone restoration stimulation in periodontal condition. The electrical signal is applied to an inductive mark that will create and impregnate magnetic field in diseased tissue. The device also monitors the status of the electromagnetic field. Controlled wave forms and pulse frequency signal at programmable intervals are obtained with optimized number of components and miniaturized using surface mounting devices (SMD) circuits and surface mounting technology (SMT), with enhanced protection against abnormal current growth, given the intra-oral environment. The system is powered by an autonomous power supply (battery), to limit the problems caused by powering medical equipment from the main power supply. Currently the device is used in clinical testing, in cycles of six up to twelve months. Basic principles for the electrical scheme and algorithms for pulse generation, pulse control, electromagnetic field control and automation of current monitoring are presented, together with the friendly user interface, suitable for medical data and patient monitoring.

  7. Heat Radiators for Electromagnetic Pumps

    NASA Technical Reports Server (NTRS)

    Campana, R. J.

    1986-01-01

    Report proposes use of carbon/carbon composite radiators in electromagnetic coolant pumps of nuclear reactors on spacecraft. Carbon/carbon composite materials function well at temperatures in excess of 2,200 K. Aluminum has melting temperature of only 880 K.

  8. Electromagnetic Environmental Effects System Testing

    DTIC Science & Technology

    2009-09-02

    4) Anritsu 68369A/NV. e. Stub Radiator. f . Capacitor, 10 microfara, Solar Electronics 6512-106R, 7113-106R, or similar. g. LISNs, Solar ...GENERATED ELECTROSTATIC DISCHARGE (HESD) ............................................................................. E-1 F . PRECIPITATION...STATIC (P-STATIC) ................................................ F -1 G. HAZARDS OF ELECTROMAGNETIC RADIATION TO FUEL (HERF

  9. Explanations, Education, and Electromagnetic Fields.

    ERIC Educational Resources Information Center

    Friedman, Sharon M.

    Explaining complex scientific and environmental subjects in the mass media is difficult to do, particularly under such constraints as short deadlines and lack of space or time. When a scientific controversy and human health risk are involved, this becomes an even harder task to accomplish. The subject of electromagnetic fields (EMF) involves…

  10. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  11. Electromagnetic Phenomena in Cosmical Physics

    NASA Astrophysics Data System (ADS)

    Lehnert, B.

    2016-06-01

    Part I. Magneto-Hydrodynamics; Section A. Theory; Part II. Solar Electrodynamics; Part III. Stellar Magnetism; Part IV. Solar and Interplanetary Magnetic Fields; Part V. Electromagnetic State in Interplanetary Space; Section A. Theories of Magnetic Storms; Part VI. High Current Discharges; Part VII. Additional Contributions.

  12. Joint Electromagnetic Spectrum Management Operations

    DTIC Science & Technology

    2012-03-20

    synchronizing, and deconflicting JEMSMO actions (p. IV-7) Doctrine Update for JP 6-01, Joint Electromagnetic Spectrum Management Operations...communications system directorate of a joint staff (J-6), to support joint planning, coordination, and control of the spectrum for assigned forces. Executive...in the respective Service or joint publications. Interference Resolution To ensure critical frequencies and spectrum-dependent systems are

  13. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Numerous cases in this year's chapter dealt with the same topics of previous years--contracts and bids for building construction, and detachment and annexation of a portion of a school district. The courts continued to attribute board discretionary authority to school boards in school property matters. Intergovernmental disputes over ownership or…

  14. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    This chapter summarizes and analyze all state supreme court and federal court decisions as well as other significant court decisions involving school property. The cases discussed are generally limited to those decided during 1974 and reported in the General Digest on or before March 1, 1975. In their discussion, the authors attempt to integrate…

  15. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    A review of cases involving higher education property matters shows that many are concerned with building construction, equipment installation, or repair contracts. A number of other cases involve routine conflicts between colleges or universities and other governmental entities over matters such as requests for special exceptions to zoning…

  16. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    This chapter summarizes recent state supreme court and federal court decisions involving school property. The cases discussed are generally limited to those decided during 1975 and reported in the General Digest as of March 1976. In their discussion, the authors attempt to integrate related cases and to illuminate any unifying legal principles…

  17. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Reflecting widespread unhappiness with the growing tax burdens in this country, the most active area of litigation reported in the property chapter this year involves various attempts by taxpayers to prevent the construction or remodeling of public school facilities. While some taxpayers fought to keep schools from being built, others in New York…

  18. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    The author notes that controversies over construction bids and contracts continue to represent the largest number of property cases reported in this year's chapter. Most of these cases are routine disputes between colleges or universities and contractors over such issues as the return of bid bonds, recovery of additional costs for construction…

  19. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Johnson, Margaret M.

    While the number of cases dealing with school property issues was significantly lower than in previous years, a significant number of cases involving the detachment and attachment of land to school districts arose. Eight of the eleven cases dealing with land detachment come from Illinois. The cases concerned requests from parents that their…

  20. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    While the types of cases reported in this year's chapter are essentially the same as those reported in last year's, the number of certain types of cases have changed--in some instances significantly. For example, the number of cases raising constitutional issues in the areas of school construction, location, and property use have declined. On the…

  1. Free-standing THz electromagnetic metamaterials.

    PubMed

    Moser, H O; Kong, J A; Jian, L K; Chen, H S; Liu, G; Bahou, M; Kalaiselvi, S M P; Maniam, S M; Cheng, X X; Wu, B I; Gu, P D; Chen, A; Heussler, S P; bin Mahmood, Shahrain; Wen, L

    2008-09-01

    Using micromanufactured S-shaped gold strings suspended in free space by means of window-frames, we experimentally demonstrate an electromagnetic meta-material (EM(3)) in which the metallic structures are no longer embedded in matrices or deposited on substrates such that the response is solely determined by the geometrical parameters and the properties of the metal. Two carefully aligned and assembled window-frames form a bi-layer chip that exhibits 2D left-handed pass-bands corresponding to two different magnetic resonant loops in the range of 1.4 to 2.2 THz as characterized by Fourier transform interferometry and numerical simulation. Chips have a comparably large useful area of 56 mm(2). Our results are a step towards providing EM(3) that fulfill the common notions of a material.

  2. Electromagnetic fields with vanishing scalar invariants

    NASA Astrophysics Data System (ADS)

    Ortaggio, Marcello; Pravda, Vojtěch

    2016-06-01

    We determine the class of p-forms {\\boldsymbol{F}} that possess vanishing scalar invariants (VSIs) at arbitrary order in an n-dimensional spacetime. Namely, we prove that {\\boldsymbol{F}} is a VSI if and only if if it is of type N, its multiple null direction {\\boldsymbol{\\ell }} is ‘degenerate Kundt’, and {\\pounds }{\\boldsymbol{\\ell }}{\\boldsymbol{F}}=0. The result is theory-independent. Next, we discuss the special case of Maxwell fields, both at the level of test fields and of the full Einstein-Maxwell equations. These describe electromagnetic non-expanding waves propagating in various Kundt spacetimes. We further point out that a subset of these solutions possesses a universal property, i.e. they also solve (virtually) any generalized (non-linear and with higher derivatives) electrodynamics, possibly also coupled to Einstein’s gravity.

  3. Electromagnetic waves in a strong Schwarzschild plasma

    SciTech Connect

    Daniel, J.; Tajima, T.

    1996-11-01

    The physics of high frequency electromagnetic waves in a general relativistic plasma with the Schwarzschild metric is studied. Based on the 3 + 1 formalism, we conformalize Maxwell`s equations. The derived dispersion relations for waves in the plasma contain the lapse function in the plasma parameters such as in the plasma frequency and cyclotron frequency, but otherwise look {open_quotes}flat.{close_quotes} Because of this property this formulation is ideal for nonlinear self-consistent particle (PIC) simulation. Some of the physical consequences arising from the general relativistic lapse function as well as from the effects specific to the plasma background distribution (such as density and magnetic field) give rise to nonuniform wave equations and their associated phenomena, such as wave resonance, cutoff, and mode-conversion. These phenomena are expected to characterize the spectroscopy of radiation emitted by the plasma around the black hole. PIC simulation results of electron-positron plasma are also presented.

  4. Collectivity and electromagnetic radiation in small systems

    NASA Astrophysics Data System (ADS)

    Shen, Chun; Paquet, Jean-François; Denicol, Gabriel S.; Jeon, Sangyong; Gale, Charles

    2017-01-01

    Collective behavior has been observed in hadronic measurements of high multiplicity proton+lead collisions at the Large Hadron Collider, as well as in (proton, deuteron, helium-3) + gold collisions at the Relativistic Heavy Ion Collider. To better understand the evolution dynamics and the properties of the matter created in these small systems, a systematic study of the soft hadronic observables together with electromagnetic radiation from these collisions is performed by using a hydrodynamic framework. Quantitative agreement is found between theoretical calculations and existing experimental hadronic observables. The validity of the fluid-dynamical description is estimated by calculating Knudsen and inverse Reynolds numbers. Sizeable thermal yields are predicted for low-pT photons. Further predictions of higher-order charged hadron anisotropic flow coefficients and of thermal photon enhancement are proposed.

  5. Influence of steel casings on electromagnetic signals

    SciTech Connect

    Wu, X.; Habashy, T.M. )

    1994-03-01

    Most wells in oil fields are cased with metal. The feasibility of measuring low-frequency magnetic fields through such steel-cased wells is of great interest for monitoring fluid movement during production. The authors report on experimental and modeling results regarding the effect of steel casing on electromagnetic signals transmitted through them. This effect includes the attenuation and phase shift of a signal diffusing through the casing wall. Sample casings are studied under low field strength in the linear regime where the casing's electrical properties are independent of the applied signals. Frequency spectra are measured for transverse-electric and transverse-magnetic polarizations from 0.1 Hz to 1 kHz. Numerical models, developed to simulate the casing response, match the experimental data very well. Finally, studies of the effects of the earth's magnetic field and casing remnant magnetization show that these steady biases do not affect the ac signal detection.

  6. Impact of Low Frequency Electromagnetic Field Exposure on the Candida Albicans

    NASA Astrophysics Data System (ADS)

    Malíková, Ivona; Janoušek, Ladislav; Fantova, Vladyslava; Jíra, Jaroslav; Kříha, Vítĕzslav

    2015-03-01

    Effect of low frequency electromagnetic field on growth of selected microorganism is studied in the article. The diploid fungus that grows both as yeast and filamentous cell was chosen for this research. The theory of ion parametric resonance was taken as the base for studying the influence of electromagnetic field on biological structures. We tested the hypothesis, whether it is possible to observe the change in growth properties of Candida albicans with an AC electromagnetic field tuned to resonance with calcium ions cyclotron frequency.

  7. Dynamic model for electromagnetic field and heating patterns in loaded cylindrical cavities

    SciTech Connect

    Tian, Y.L.; Black, W.M.; Sa`adaldin, H.S.; Ahmad, I.; Silberglitt, R.

    1995-07-01

    An analytical solution for the electromagnetic fields in a cylindrical cavity, partially filled with a cylindrical dielectric has been recently reported. A program based on this solution has been developed and combined with the authors` previous program for heat transfer analysis. The new software has been used to simulate the dynamic temperature profiles of microwave heating and to investigate the role of electromagnetic field in heating uniformity and stability. The effects of cavity mode, cavity dimension, the dielectric properties of loads on electromagnetic field and heating patterns can be predicted using this software.

  8. Electromagnetic and nuclear radiation detector using micromechanical sensors

    DOEpatents

    Thundat, Thomas G.; Warmack, Robert J.; Wachter, Eric A.

    2000-01-01

    Electromagnetic and nuclear radiation is detected by micromechanical sensors that can be coated with various interactive materials. As the micromechanical sensors absorb radiation, the sensors bend and/or undergo a shift in resonance characteristics. The bending and resonance changes are detected with high sensitivity by any of several detection methods including optical, capacitive, and piezoresistive methods. Wide bands of the electromagnetic spectrum can be imaged with picoJoule sensitivity, and specific absorptive coatings can be used for selective sensitivity in specific wavelength bands. Microcantilevers coated with optical cross-linking polymers are useful as integrating optical radiation dosimeters. Nuclear radiation dosimetry is possible by fabricating cantilevers from materials that are sensitive to various nuclear particles or radiation. Upon exposure to radiation, the cantilever bends due to stress and its resonance frequency shifts due to changes in elastic properties, based on cantilever shape and properties of the coating.

  9. Characterization of Meta-Materials Using Computational Electromagnetic Methods

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar; Shin, Joon

    2005-01-01

    An efficient and powerful computational method is presented to synthesize a meta-material to specified electromagnetic properties. Using the periodicity of meta-materials, the Finite Element Methodology (FEM) is developed to estimate the reflection and transmission through the meta-material structure for a normal plane wave incidence. For efficient computations of the reflection and transmission over a wide band frequency range through a meta-material a Finite Difference Time Domain (FDTD) approach is also developed. Using the Nicholson-Ross method and the Genetic Algorithms, a robust procedure to extract electromagnetic properties of meta-material from the knowledge of its reflection and transmission coefficients is described. Few numerical examples are also presented to validate the present approach.

  10. TOPICAL REVIEW: Electromagnetic techniques for moisture content determination of materials

    NASA Astrophysics Data System (ADS)

    Kaatze, Udo; Hübner, Christof

    2010-08-01

    Based on a short introduction to the dielectric properties of water and aqueous solutions, this review summarizes current techniques of electromagnetic aquametry. The techniques described here include time-domain and frequency-domain procedures, enabling moisture determination in a broad spectral range from millihertz to terahertz frequencies. In this review, quasi-static capacitance and impedance approaches as well as microwave and submillimetre wave reflection, transmission and resonant methods are presented. Sensor configurations and electronic measurement setups, including remote sensing, are discussed briefly. A broad spectrum of applications is introduced to show the extended usability of electromagnetic techniques of moisture content determination. The dielectric properties of some reference materials, suitable for the calibration of sensors and of electronic measurement devices, are tabulated. Reference is also made to some dielectric models of water-containing materials and to superior evaluation routines.

  11. Enhanced Microfluidic Electromagnetic Measurements

    NASA Technical Reports Server (NTRS)

    Giovangrandi, Laurent (Inventor); Ricco, Antonio J. (Inventor); Kovacs, Gregory (Inventor)

    2015-01-01

    Techniques for enhanced microfluidic impedance spectroscopy include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. Flow in the channel is laminar. A dielectric constant of a fluid constituting either sheath flow is much less than a dielectric constant of the core fluid. Electrical impedance is measured in the channel between at least a first pair of electrodes. In some embodiments, enhanced optical measurements include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. An optical index of refraction of a fluid constituting either sheath flow is much less than an optical index of refraction of the core fluid. An optical property is measured in the channel.

  12. Electromagnetic acoustic transducer

    DOEpatents

    Alers, George A.; Burns, Jr., Leigh R.; MacLauchlan, Daniel T.

    1988-01-01

    A noncontact ultrasonic transducer for studying the acoustic properties of a metal workpiece includes a generally planar magnetizing coil positioned above the surface of the workpiece, and a generally planar eddy current coil between the magnetizing coil and the workpiece. When a large current is passed through the magnetizing coil, a large magnetic field is applied to the near-surface regions of the workpiece. The eddy current coil can then be operated as a transmitter by passing an alternating current therethrough to excite ultrasonic waves in the surface of the workpiece, or operated as a passive receiver to sense ultrasonic waves in the surface by measuring the output signal. The geometries of the two coils can be varied widely to be effective for different types of ultrasonic waves. The coils are preferably packaged in a housing which does not interfere with their operation, but protects them from a variety of adverse environmental conditions.

  13. Strong permanent magnet-assisted electromagnetic undulator

    DOEpatents

    Halbach, Klaus

    1988-01-01

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

  14. Generation of stochastic electromagnetic beams with complete controllable coherence.

    PubMed

    Chen, Xudong; Chang, Chengcheng; Chen, Ziyang; Lin, Zhili; Pu, Jixiong

    2016-09-19

    We generate a stochastic electromagnetic beam (SEB) with complete controllable coherence, that is, the coherence degree can be controlled independently along two mutually perpendicular directions. We control the coherence of the SEB by adjusting the phase modulation magnitude applied onto two crossed phase only spatial light modulators. We measure the beam's coherence properties using Young's interference experiment, as well as the beam propagation factor. It is shown that the experimental results are consistent with our theoretical predictions.

  15. Optimal control of electromagnetic field using metallic nanoclusters

    NASA Astrophysics Data System (ADS)

    Grigorenko, Ilya; Haas, Stephan; Balatsky, Alexander; Levi, A. F. J.

    2008-04-01

    The dielectric properties of metallic nanoclusters in the presence of an applied electromagnetic field are investigated using the non-local linear response theory. In the quantum limit we find a nontrivial dependence of the induced field and charge distributions on the spatial separation between the clusters and on the frequency of the driving field. Using a genetic algorithm, these quantum functionalities are exploited to custom-design sub-wavelength lenses with a frequency-controlled switching capability.

  16. Para: a computer simulation code for plasma driven electromagnetic launchers

    SciTech Connect

    Thio, Y.-C.

    1983-03-01

    A computer code for simulation of rail-type accelerators utilizing a plasma armature has been developed and is described in detail. Some time varying properties of the plasma are taken into account in this code thus allowing the development of a dynamical model of the behavior of a plasma in a rail-type electromagnetic launcher. The code is being successfully used to predict and analyse experiments on small calibre rail-gun launchers.

  17. Deeply subwavelength electromagnetic Tamm states in graphene metamaterials

    NASA Astrophysics Data System (ADS)

    Smirnova, Daria; Buslaev, Pavel; Iorsh, Ivan; Shadrivov, Ilya V.; Belov, Pavel A.; Kivshar, Yuri S.

    2014-06-01

    We study localized modes at a surface of a multilayer structure made of graphene layers separated by dielectric layers. We demonstrate the existence of deeply subwavelength surface modes that can be associated with the electromagnetic Tamm states, with the frequencies in the THz frequency range the negative group velocities. We suggest that the dispersion properties of these Tamm surface modes can be tuned by varying the thickness of a dielectric cap layer.

  18. Minimizing the Reflection of Electromagnetic Waves by Surface Impedance.

    DTIC Science & Technology

    1986-07-01

    Chen2’ and G. Crosta3 ,** Technical Summary Report #2942 July 1986 ABSTRACT In an empty halfspace a point source emits electromagnetic waves of fixed...are determined by means of the geometrical optics approximation. An optimization method is used to compute the surface impedance, which minimizes a...given function of the e.m. fields (e.g. the average energy density) at a given observation point . The properties of the functions to be minimized are

  19. Nonlinear Electromagnetics and Coherent Energy Transfer in Negative-Index metamaterials

    DTIC Science & Technology

    2014-08-07

    AFRL-OSR-VA-TR-2014-0176 NONLINEAR ELECTROMAGNETICS AND COHERENT ENERGY TRANSFER IN NEGATIVE INDEX METAMATERIALS Alexander Popov UNIVERSITY OF...COHERENT ENERGY TRANSFER IN NEGATIVE-INDEX METAMATERIALS FA9550-12-1-0298 Popov, Alexander K. UNIVERSITY OF WISCONSIN-STEVENS POINT 2100 MAIN ST STEVENS...understanding was advanced of nonlinear propagation properties of electromagnetic (EM) waves in double-domain negative/positive index metamaterials (MMs

  20. Second-order statistics of stochastic electromagnetic beams propagating through non-Kolmogorov turbulence.

    PubMed

    Shchepakina, Elena; Korotkova, Olga

    2010-05-10

    We present a detailed investigation, qualitative and quantitative, on how the atmospheric turbulence with a non-Kolmogorov power spectrum affects the major statistics of stochastic electromagnetic beams, such as the spectral composition and the states of coherence and polarization. We suggest a detailed survey on how these properties evolve on propagation of beams generated by electromagnetic Gaussian Schell-model sources, depending on the fractal constant alpha of the atmospheric power spectrum.

  1. Electromagnetic Compatibility Testing Studies

    NASA Technical Reports Server (NTRS)

    Trost, Thomas F.; Mitra, Atindra K.

    1996-01-01

    This report discusses the results on analytical models and measurement and simulation of statistical properties from a study of microwave reverberation (mode-stirred) chambers performed at Texas Tech University. Two analytical models of power transfer vs. frequency in a chamber, one for antenna-to-antenna transfer and the other for antenna to D-dot sensor, were experimentally validated in our chamber. Two examples are presented of the measurement and calculation of chamber Q, one for each of the models. Measurements of EM power density validate a theoretical probability distribution on and away from the chamber walls and also yield a distribution with larger standard deviation at frequencies below the range of validity of the theory. Measurements of EM power density at pairs of points which validate a theoretical spatial correlation function on the chamber walls and also yield a correlation function with larger correlation length, R(sub corr), at frequencies below the range of validity of the theory. A numerical simulation, employing a rectangular cavity with a moving wall shows agreement with the measurements. The determination that the lowest frequency at which the theoretical spatial correlation function is valid in our chamber is considerably higher than the lowest frequency recommended by current guidelines for utilizing reverberation chambers in EMC testing. Two suggestions have been made for future studies related to EMC testing.

  2. Inspecting Friction Stir Welding using Electromagnetic Probes

    NASA Technical Reports Server (NTRS)

    Kinchen, David G.

    2004-01-01

    A report describes the use of advanced electromagnetic probes to measure the dimensions, the spatial distribution of electrical conductivity, and related other properties of friction stir welds (FSWs) between parts made of the same or different aluminum alloy(s). The probes are of the type described in in another Tech Brief. To recapitulate: A probe of this type is essentially an eddy-current probe that includes a primary (driver) winding that meanders and multiple secondary (sensing) windings that meander along the primary winding. Electrical conductivity is commonly used as a measure of heat treatment and tempering of aluminum alloys, but prior to the development of these probes, the inadequate sensitivity and limited accuracy of electrical-conductivity probes precluded such use on FSWs between different aluminum alloys, and the resolution of those probes was inadequate for measurement of FSW dimensions with positions and metallurgical properties. In contrast, the present probes afford adequate accuracy and spatial resolution for the purposes of measuring the dimensions of FSW welds and correlating spatially varying electrical conductivities with metallurgical properties, including surface defects.

  3. Magnetic correlates in electromagnetic consciousness.

    PubMed

    Liboff, A R

    2016-01-01

    We examine the hypothesis that consciousness is a manifestation of the electromagnetic field, finding supportive factors not previously considered. It is not likely that traditional electrophysiological signaling modes can be readily transmitted throughout the brain to properly enable this field because of electric field screening arising from the ubiquitous distribution of high dielectric lipid membranes, a problem that vanishes for low-frequency magnetic fields. Many reports over the last few decades have provided evidence that living tissue is robustly sensitive to ultrasmall (1-100 nT) ELF magnetic fields overlapping the γ-frequency range often associated with awareness. An example taken from animal behavior (coherent bird flocking) lends support to the possibility of a disembodied electromagnetic consciousness. In contrast to quantum consciousness hypotheses, the present approach is open to experimental trial.

  4. Electromagnetic transduction of ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Passarelli, Frank; Alers, George; Alers, Ron

    2012-05-01

    Excitation and detection of ultrasonic vibrations without physical contact has proven to be of great commercial value. First used to excite the resonant vibration of bar shaped laboratory specimens in the 1930's, it was Bruce Thompson's contributions in 1973-5 that launched their practical application to a wide range of difficult NDE problems. As a fresh PhD, he championed the use of mathematical models for the electromagnetic transduction process in order to guide the design and construction of practical transducers. His early papers presented both theoretical and experimental results that exposed the wide range of wave types that could be generated along with the environmental conditions that could be overcome. Several laboratories around the world established research programs to apply the electromagnetic transducer (EMAT) to specific NDE problems. This paper will summarize those applications made by the authors.

  5. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, Alan W.

    1995-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

  6. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, A.W.

    1995-08-08

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

  7. Cellular Effects of Electromagnetic Radiation.

    DTIC Science & Technology

    2014-09-26

    cells of characean algae were examined for electrophysiological sequelae to acute electromagnetic field irradiation at 10 mW/cm Carrier frequencies...the low frequency excess noise in single cells of characean algae . J. Microwave Power _Z, 43-46 (1985). E63 A. V. Gokhale and W. F. Pickard, Extremely...A giant cell of a characean alga (normally about 15 mm long and 300 .um in diameter) would be placed in the channel downsteam from the strip, impaled

  8. Electromagnetic Calorimeter for HADES Experiment

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ramos, P.; Chlad, L.; Epple, E.; Fabbietti, L.; Galatyuk, T.; Golubeva, M.; Guber, F.; Hlaváč, S.; Ivashkin, A.; Kajetanowic, M.; Kardan, B.; Koenig, W.; Korcyl, G.; Kugler, A.; Lapidus, K.; Linev, S.; Lisowski, E.; Neiser, A.; Ott, O.; Otte, O.; Pethukov, O.; Pietraszko, J.; Reshetin, A.; Rost, A.; Salabura, P.; Sobolev, Y. G.; Svoboda, O.; Thomas, A.; Tlusty, P.; Traxler, M.

    2014-11-01

    Electromagnetic calorimeter (ECAL) is being developed to complement dilepton spectrometer HADES. ECAL will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 AGeV on the beam of future accelerator SIS100@FAIR. We will report results of the last beam test with quasi-monoenergetic photons carried out in MAMI facility at Johannes Gutenberg Universität Mainz.

  9. Genetic Effects of Electromagnetic Waves

    NASA Astrophysics Data System (ADS)

    Aroutiounian, Rouben; Hovhannisyan, Galina; Gasparian, Gennady

    The genetic effects of electromagnetic waves can be detected by different test-systems. The mutagenic effect of ionizing radiation can be developed on the levels of DNA and/or chromosomes. In numerous researches efficiency of micronucleus assay, alkaline single-cell gel electrophoresis, chromosomal aberrations test and FISH-technique and their different combinations for the detection of ionizing radiation-induced genotoxic effects are discussed. Also some molecular-biological approaches developed in the last years are presented.

  10. Electromagnetic brake/clutch device

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1994-01-01

    An electromagnetic brake/clutch device includes a drive shaft supported by at least one bearing for transmitting torque, a housing, affixed to prevent its rotation, surrounding the drive shaft, and an electromagnetically activated device within the housing to selectively prevent and allow rotation of the drive shaft. The electromagnetically activated device includes a plurality of cammed rollers to prevent counter-clockwise rotation of the drive shaft. The drive shaft includes a circumferential disk and the housing includes a reaction ring for engagement with the plurality of cammed rollers. The plurality of cammed rollers are released from engagement with the circumferential disk and the reaction ring by a plurality of tripping mechanisms within the housing. The tripping action uses the locking force to act as a release force merely by changing the boundary conditions of the roller interface angles. The tripping mechanisms include trippers for disengaging the plurality of cammed rollers and an anvil shaped portion for providing lateral movement of the trippers. The plurality of cammed rollers is preloaded to engagement with the circumferential disk and reaction ring by a spring, and is located with respect to an adjacent tripping mechanism with another spring.

  11. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    SciTech Connect

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-04-15

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  12. Spatial transformation-enabled electromagnetic devices: from radio frequencies to optical wavelengths

    PubMed Central

    Jiang, Zhi Hao; Turpin, Jeremy P.; Morgan, Kennith; Lu, Bingqian; Werner, Douglas H.

    2015-01-01

    Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes. PMID:26217054

  13. Spatial transformation-enabled electromagnetic devices: from radio frequencies to optical wavelengths.

    PubMed

    Jiang, Zhi Hao; Turpin, Jeremy P; Morgan, Kennith; Lu, Bingqian; Werner, Douglas H

    2015-08-28

    Transformation optics provides scientists and engineers with a new powerful design paradigm to manipulate the flow of electromagnetic waves in a user-defined manner and with unprecedented flexibility, by controlling the spatial distribution of the electromagnetic properties of a medium. Using this approach, over the past decade, various previously undiscovered physical wave phenomena have been revealed and novel electromagnetic devices have been demonstrated throughout the electromagnetic spectrum. In this paper, we present versatile theoretical and experimental investigations on designing transformation optics-enabled devices for shaping electromagnetic wave radiation and guidance, at both radio frequencies and optical wavelengths. Different from conventional coordinate transformations, more advanced and versatile coordinate transformations are exploited here to benefit diverse applications, thereby providing expanded design flexibility, enhanced device performance, as well as reduced implementation complexity. These design examples demonstrate the comprehensive capability of transformation optics in controlling electromagnetic waves, while the associated novel devices will open up new paths towards future integrated electromagnetic component synthesis and design, from microwave to optical spectral regimes.

  14. Electromagnetic Effects in SDF Explosions

    SciTech Connect

    Reichenbach, H; Neuwald, P; Kuhl, A L

    2010-02-12

    The notion of high ion and electron concentrations in the detonation of aluminized explosive mixtures has aroused some interest in electro-magnetic effects that the SDF charges might generate when detonated. Motivated by this interest we have started to investigate whether significant electro-magnetic effects show up in our small-scale experiments. However, the design of instrumentation for this purpose is far from straightforward, since there are a number of open questions. Thus the main aim of the feasibility tests is to find - if possible - a simple and reliable method that can be used as a diagnostic tool for electro-magnetic effects. SDF charges with a 0.5-g PETN booster and a filling of 1 g aluminum flakes have been investigated in three barometric bomb calorimeters with volumes ranging from 6.3 l to of 6.6 l. Though similar in volume, the barometric bombs differed in the length-to-diameter ratio. The tests were carried out with the bombs filled with either air or nitrogen at ambient pressure. The comparison of the test in air to those in nitrogen shows that the combustion of TNT detonation products or aluminum generates a substantial increase of the quasi-steady overpressure in the bombs. Repeated tests in the same configuration resulted in some scatter of the experimental results. The most likely reason is that the aluminum combustion in most or all cases is incomplete and that the amount of aluminum actually burned varies from test to test. The mass fraction burned apparently decreases with increasing aspect ratio L/D. Thus an L/D-ratio of about 1 is optimal for the performance of shock-dispersed-fuel combustion. However, at an L/D-ratio of about 5 the combustion still yields appreciable overpressure in excess of the detonation. For a multi-burst scenario in a tunnel environment with a number of SDF charges distributed along a tunnel section a spacing of 5 tunnel diameter and a fuel-specific volume of around 7 l/g might provide an acceptable compromise

  15. Electromagnetic interference shielding effectiveness of polypropylene/conducting fiber composites

    NASA Astrophysics Data System (ADS)

    Lee, Pyoung-Chan; Kim, Bo-Ram; Jeoung, Sun Kyoung; Kim, Yeung Keun

    2016-03-01

    Electromagnetic released from the automotive electronic parts is harmful to human body. Electromagnetic interference (EMT) shielding refers to the reflection and/or adsorption of electromagnetic radiation by a material, which thereby acts as a shield against the penetration of the radiation through the shield. Polypropylene (PP)/conductive micro fiber composites containing various fiber contents and fiber length were injection-molded. The effect of fiber content and length on electrical properties of the composites was studied by electrical resistivity and EMT shielding measurements. The through-plane electrical conductivity and dielectric permittivity were obtained by measuring dielectric properties. The EMT shielding effectiveness (SE) was investigated by using S-parameter in the range of 100 ~ 1500 MHz. Reflection, absorption and multiple-reflection are the EMT attenuation mechanisms. From the measurement of S-Parameters, the absorption coefficient, reflection coefficient, and the shielding efficiency of the materials were calculated. The EMT SE of PP/conducing fiber composites is 40 dB over a wide frequency range up to 1.5 GHz, which is higher than that of PP/talc composite used automotive parts, viz. 0 dB.

  16. Manager's Role in Electromagnetic Interference (EMI) Control

    NASA Technical Reports Server (NTRS)

    Sargent, Noel B.; Lewis, Catherine C.

    2013-01-01

    This presentation captures the essence of electromagnetic compatibility (EMC) engineering from a project manager's perspective. It explains the basics of EMC and the benefits to the project of early incorporation of EMC best practices. The EMC requirement products during a project life cycle are identified, along with the requirement verification methods that should be utilized. The goal of the presentation is to raise awareness and simplify the mystique surrounding electromagnetic compatibility for managers that have little or no electromagnetics background

  17. Electromagnetic imaging methods for nondestructive evaluation applications.

    PubMed

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions.

  18. Anisotropic conducting films for electromagnetic radiation applications

    DOEpatents

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  19. Nondestructive Electromagnetic Characterization of Uniaxial Materials

    DTIC Science & Technology

    2014-09-18

    NONDESTRUCTIVE ELECTROMAGNETIC CHARACTERIZATION OF UNIAXIAL MATERIALS DISSERTATION Neil G. Rogers, Captain, USAF AFIT-ENG-DS-14-S-05 DEPARTMENT OF...not subject to copyright protection in the United States. AFIT-ENG-DS-14-S-05 NONDESTRUCTIVE ELECTROMAGNETIC CHARACTERIZATION OF UNIAXIAL MATERIALS...September 2014 DISTRIBUTION STATEMENT A: APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENG-DS-14-S-05 NONDESTRUCTIVE ELECTROMAGNETIC

  20. Thin sheet casting with electromagnetic pressurization

    SciTech Connect

    Walk, Steven R.; Slepian, R. Michael; Nathenson, Richard D.; Williams, Robert S.

    1991-01-01

    An apparatus, method and system for the casting of thin strips or strips of metal upon a moving chill block that includes an electromagnet located so that molten metal poured from a reservoir onto the chill block passes into the magnetic field produced by the electromagnet. The electromagnet produces a force on the molten metal on said chill block in the direction toward said chill block in order to enhance thermal contact between the molten metal and the chill block.

  1. Electromagnetic Imaging Methods for Nondestructive Evaluation Applications

    PubMed Central

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions. PMID:22247693

  2. An inhomogeneous thermal block model of man for the electromagnetic environment

    SciTech Connect

    Chatterjee, I.; Gandhi, O.P.

    1983-11-01

    An inhomogeneous four layer block thermal model of a human body, composed of 476 electromagnetic-sensitive cubical cells has been developed to study the effects of electromagnetic radiation. Varying tissue properties defined by thermal conductivity, specific heat, blood flow rate and metabolic heat production are accounted for by equations. Peripheral cell temperature is weight-averaged for total cell volume and is thereby higher than actual skin temperature. During electromagnetic field exposure, additional factors considered are increased blood flow rate caused by vasodilation and sweat-induced heat loss. Hot spots have been located in the model and numerical results are presented. Subjected to plane wave iradiation, the model's sweating and insensible perspiration cease and all temperatures converge. Testing during electromagnetic hyperthemia shows all temperature body parts to increase approximately at the same rate.

  3. Hypothesis on how to measure electromagnetic hypersensitivity.

    PubMed

    Tuengler, Andreas; von Klitzing, Lebrecht

    2013-09-01

    Electromagnetic hypersensitivity (EHS) is an ill-defined term to describe the fact that people who experience health symptoms in the vicinity of electromagnetic fields (EMFs) regard them as causal for their complaints. Up to now most scientists assume a psychological cause for the suffering of electromagnetic hypersensitive individuals. This paper addresses reasons why most provocation studies could not find any association between EMF exposure and EHS and presents a hypothesis on diagnosis and differentiation of this condition. Simultaneous recordings of heart rate variability, microcirculation and electric skin potentials are used for classification of EHS. Thus, it could be possible to distinguish "genuine" electromagnetic hypersensitive individuals from those who suffer from other conditions.

  4. Visualization Of Electromagnetic Environment Near GSM Antennae

    NASA Astrophysics Data System (ADS)

    Zvezdina, M. Yu; Shokova, Yu A.; Kundryukova, N. I.; Kutukova, V. D.; Pozdnyakova, A. V.

    2017-01-01

    Web-enabled mobile phone enhancement has determined a sharp increase of mobile base station quantity, which has led to a surge of electromagnetic noise in metropolitan areas. Electromagnetic noise permanently influences adult and child population; the impossibility to remove this impact has promoted the electromagnetic monitoring. The most accessible form of socially oriented monitoring is a visualization of energy flux density for GSM base station antennae. Forecast calculation routines take antenna construction and location into an account; they also allow giving the recommendations on electromagnetic environment improvement basing on physical interpretation the obtained results.

  5. Noncontacting ultrasonic and electromagnetic HTS tape NDE

    SciTech Connect

    Telschow, K.L.; Bruneel, F.W.; Walter, J.B.; Koo, L.S.

    1996-10-01

    Two noncontacting nondestructive evaluation techniques (electromagnetic and ultrasonic) for inspection of high temperature superconducting tapes are described. Results for Ag-clad BSCCO tapes are given.

  6. Electromagnetic Compatibility for the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Scully, Robert C.

    2004-01-01

    This slide presentation reviews the Space Shuttle electromagnetic compatibility (EMC). It includes an overview of the design of the shuttle with the areas that are of concern for the electromagnetic compatibility. It includes discussion of classical electromagnetic interference (EMI) and the work performed to control the electromagnetic interference. Another area of interest is electrostatic charging and the threat of electrostatic discharge and the attempts to reduce damage to the Shuttle from these possible hazards. The issue of electrical bonding is als reviewed. Lastly the presentation reviews the work performed to protect the shuttle from lightning, both in flight and on the ground.

  7. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

  8. Electromagnetic rogue waves in beam-plasma interactions

    NASA Astrophysics Data System (ADS)

    Veldes, G. P.; Borhanian, J.; McKerr, M.; Saxena, V.; Frantzeskakis, D. J.; Kourakis, I.

    2013-06-01

    The occurrence of rogue waves (freak waves) associated with electromagnetic pulse propagation interacting with a plasma is investigated, from first principles. A multiscale technique is employed to solve the fluid Maxwell equations describing weakly nonlinear circularly polarized electromagnetic pulses in magnetized plasmas. A nonlinear Schrödinger (NLS) type equation is shown to govern the amplitude of the vector potential. A set of non-stationary envelope solutions of the NLS equation are considered as potential candidates for the modeling of rogue waves (freak waves) in beam-plasma interactions, namely in the form of the Peregrine soliton, the Akhmediev breather and the Kuznetsov-Ma breather. The variation of the structural properties of the latter structures with relevant plasma parameters is investigated, in particular focusing on the ratio between the (magnetic field dependent) cyclotron (gyro-)frequency and the plasma frequency.

  9. Control of electronic transport in graphene by electromagnetic dressing

    PubMed Central

    Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.

    2016-01-01

    We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) electronic transport in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control electronic properties of graphene with light. PMID:26838371

  10. Winding insulation in electromagnetic systems for Tokamak reactor plants

    NASA Astrophysics Data System (ADS)

    Maslov, V. V.; Trubachev, S. G.

    1985-01-01

    Magnetic containment of the plasma in nuclear fusion reactors of the Tokamak type requires electromagnets with insulation which must withstand high temperatures and thermal shocks as well as ionizing radiation in various forms and electric fields, and mechanical loads. Insulation materials to ensure adequate thermophysical and mechanical properties are evaluated, followed by design of insulation systems with satisfactory performance characteristics. Data on neutron fluence energy characteristics and radiation absorption doses during neutron interactions are essential for such an evaluation. Materials considered for insulation in electromagnets with superconductor and cryoresistance windings are glass mica tape with epoxy compound impregnation, glass cloth with epoxy compound impregnation (STE), polyimide glass cloth with adhesive coating (LSNL), glass Textolite with epoxy phenolic binder (STEN), epoxy resin paste with mineral fillers (PE), and polyurethane compound modified by epoxy resin with mineral filler (KPU).

  11. Grain size reduction by electromagnetic stirring inside gold alloys

    NASA Astrophysics Data System (ADS)

    Ernst, R.; Mangelinck-Noël, N.; Hamburger, J.; Garnier, C.; Ramoni, P.

    2005-06-01

    The final properties of cast materials depend greatly on the solidification process undergone by the material. In this paper, we study gold alloys dedicated to the watch industry and jewellery in the framework of a research collaboration with the Metalor Company. The aim is to improve the concentration homogeneity of the ingots by controlling the solidification step. It can be achieved by reducing segregations by a decrease in the grain size. For this purpose, we set up a multiphase electromagnetic stirring of the melt to favour the growth of finer grains and improve the homogeneity of the composition. We first design an electromagnetic stirrer by numerical simulation. The stirrer is then implemented on a model experiment. Eventually, the alloys are characterised by metallography and etching to evidence the grain structure. As expected, we obtain a substantial reduction of the grain size although, some work remains to be done to attain the final goal of even finer grains.

  12. Extremely low frequency electromagnetic fields

    SciTech Connect

    Wilson, B.W. . Chemical Sciences Dept.); Stevens, R.G. ); Anderson, L.E. . Life Sciences Center)

    1990-01-01

    The authors focus on that which seems to be the central scientific issue emerging from current ELF research in epidemiology and in the laboratory; namely, can ELF electromagnetic fields interact with biological systems in such a way as to increase cancer risk The authors examine how cancer risk might be related to two reproducible biological effects of ELF exposure: effects on the pineal gland and circadian biology, and effects on calcium homeostasis in cells. Because they are concerned with the possible biological mechanisms of carcinogenesis, epidemiological studies are only briefly reviewed.

  13. String theory in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Ambjørn, Jan; Makeenko, Yuri M.; Semenoff, Gordon W.; Szabo, Richard J.

    2003-02-01

    A review of various aspects of superstrings in background electromagnetic fields is presented. Topics covered include the Born-Infeld action, spectrum of open strings in background gauge fields, the Schwinger mechanism, finite-temperature formalism and Hagedorn behaviour in external fields, Debye screening, D-brane scattering, thermodynamics of D-branes, and noncommutative field and string theories on D-branes. The electric field instabilities are emphasized throughout and contrasted with the case of magnetic fields. A new derivation of the velocity-dependent potential between moving D-branes is presented, as is a new result for the velocity corrections to the one-loop thermal effective potential.

  14. Electromagnetic configurations of rail guns

    NASA Astrophysics Data System (ADS)

    Fat'yanov, O. V.; Ostashev, V. E.; Lopyrev, A. N.; Ul'Yanov, A. V.

    1993-06-01

    Some problems associated with the electromagnetic acceleration of macrobodies in a rail gun are examined. An approach to the design of rail gun configurations is proposed, and some basic rail gun schemes are synthesized. The alternative rail gun schemes are compared in terms of electrode potential and stability of the electrode gap with respect to parasitic current shunting. The effect of the ohmic resistance of the electrodes and of the additional magnetization field on the spatial structure of the discharge in the rail gun channel is discussed. A classification of rail gun modifications is presented.

  15. Containerless processing using electromagnetic levitation

    NASA Technical Reports Server (NTRS)

    Gokhale, A. B.; Abbaschian, R.

    1990-01-01

    The theory and practice of containerless processing via electromagnetic (EM) levitation is reviewed briefly. The use of EM levitation for the processing of alloys is described with particular emphasis on the bulk melt supercooling phenomenon in a containerless environment. The various effects associated with rapid solidification via bulk melt supercooling are discussed with examples of Nb-Si alloys. It is suggested that a detailed analysis of such effects can be utilized to select the potentially most promising alloys for future space-based processing.

  16. Electromagnetic effects on transportation systems

    SciTech Connect

    Morris, M.E.; Dinallo, M.A.

    1996-05-01

    Electronic and electrical system protection design can be used to eliminate deleterious effects from lightning, electromagnetic interference, and electrostatic discharges. Evaluation of conventional lightning protection systems using advanced computational modeling in conjunction with rocket-triggered lightning tests suggests that currently used lightning protection system design rules are inadequate and that significant improvements in best practices used for electronic and electrical system protection designs are possible. A case study of lightning induced upset and failure of a railway signal and control system is sketched.

  17. Electromagnetics

    DTIC Science & Technology

    2012-03-07

    Radiation Patterns Predicted and measured Beam Steering integration to Shadow Harvest Sensor Pod Lockheed Martin and OSU 29 DISTRIBUTION A...spatial filtering system, with an appropriate phase mask, can produce an Airy beam 18 DISTRIBUTION A: Approved for public release; distribution is...ES) arrays attain 7 dB realizable gain, 5 dB higher than any previous ES antenna . • Can be used to replace much larger Yagi antennas . • Paves

  18. Electromagnetics

    DTIC Science & Technology

    2013-03-05

    research provides optimism regarding a class of composite magnetic materials displaying significantly reduced losses • Antenna Design/Operation...Vitebskiy (AFRL/RY) “Metamaterials for the Enhancement of Light-Matter Interaction” Performance enhancement of various transceivers Dr...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Office of Scientific Research ,AFOSR/RTB,875 N. Randolph

  19. Electromagnets 1: Turn on the Power. Science in a Box.

    ERIC Educational Resources Information Center

    Whitman, Betsy Blizard

    1992-01-01

    The article presents inexpensive activities to teach elementary school students about electromagnets. Students learn to make an electromagnet with a battery, nail, and wire, then different activities help them explore the difference between permanent magnets and electromagnets. (SM)

  20. Millimeter Waves: Acoustic and Electromagnetic

    PubMed Central

    Ziskin, Marvin C.

    2012-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. PMID:22926874