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1

Ponderomotive narrow continuum (NCp) component in stimulated electromagnetic emission spectra  

Microsoft Academic Search

We present experimental results concerning the ponderomotive narrow continuum (NCp) in stimulated electromagnetic emission spectra, generated in the ionospheric F region plasma by a powerful O mode electromagnetic wave. It is found that the generation of the NCp is determined by the development of the parametric decay instability in the initial stage of the interaction of the HF pump wave

V. L. Frolov; E. N. Sergeev; G. P. Komrakov; P. Stubbe; B. Thidé; M. Waldenvik; E. Veszelei; T. B. Leyser

2004-01-01

2

Downshifted maximum features in stimulated electromagnetic emission spectra  

Microsoft Academic Search

New and detailed experimental and theoretical results concerning the prominant downshifted maximum (DM) feature in spectra of stimulated electromagnetic emissions are reported. The experimental results were obtained at the Sura ionospheric modification facility in Russia by transmitting a powerful high-frequency ordinary mode pump wave into the ionospheric F region. We present detailed experimental results of the dependence of the DM

T. B. Leyser; B. Thide; M. Waldenvik; E. Veszelei; V. L. Frolov; S. M. Grach; G. P. Komrakov

1994-01-01

3

HOT ELECTROMAGNETIC OUTFLOWS. I. ACCELERATION AND SPECTRA  

SciTech Connect

The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum-obtained by a Monte Carlo method-is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

Russo, Matthew [Department of Physics, University of Toronto, 60 St. George St., Toronto, ON M5S 1A7 (Canada); Thompson, Christopher [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada)

2013-04-20

4

Hot Electromagnetic Outflows. I. Acceleration and Spectra  

NASA Astrophysics Data System (ADS)

The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum—obtained by a Monte Carlo method—is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

Russo, Matthew; Thompson, Christopher

2013-04-01

5

The Teaching of Electromagnetism at University Level  

ERIC Educational Resources Information Center

Discusses different kinds of material presentation in the teaching of electromagnetism at the university level, including three "classical" approaches and the Keller personalized proctorial system. Indicates that a general introduction to generators and motors may be useful in an electromagnetism course. (CC)

Houldin, J. E.

1974-01-01

6

New downshifted maximum in stimulated electromagnetic emission spectra  

Microsoft Academic Search

A new spectral maximum in spectra of stimulated electromagnetic emission of the ionosphere (SEE, [1]) was detected in experiments at the SURA facility in 2008 for the pump frequencies f0 4.4-4.5 MHz, most stably for f0 = 4.3 MHz, the lowest possible pump frequency at the SURA facility. The new maximum is situated at frequency shifts ?f -6 kHz from

Evgeny Sergeev; Savely Grach

2010-01-01

7

The ALICE electromagnetic calorimeter high level triggers  

NASA Astrophysics Data System (ADS)

The ALICE (A Large Ion Collider Experiment) detector yields a huge sample of data from different sub-detectors. On-line data processing is applied to select and reduce the volume of the stored data. ALICE applies a multi-level hardware trigger scheme where fast detectors are used to feed a three-level (L0, L1, and L2) deep chain. The High-Level Trigger (HLT) is a fourth filtering stage sitting logically between the L2 trigger and the data acquisition event building. The EMCal detector comprises a large area electromagnetic calorimeter that extends the momentum measurement of photons and neutral mesons up to pT = 250 GeV/c, which improves the ALICE capability to perform jet reconstruction with measurement of the neutral energy component of jets. An online reconstruction and trigger chain has been developed within the HLT framework to sharpen the EMCal hardware triggers, by combining the central barrel tracking information with the shower reconstruction (clusters) in the calorimeter. In the present report the status and the functionality of the software components developed for the EMCal HLT online reconstruction and trigger chain will be discussed, as well as preliminary results from their commissioning performed during the 2011 LHC running period.

Ronchetti, F.; Blanco, F.; Figueredo, M.; Knospe, A. G.; Xaplanteris, L.

2012-12-01

8

Spectra  

NSDL National Science Digital Library

Spectra is a very informative website about how astronomers use spectra to understand what stars are made of, their structures, and their evolution. The page begins with an introduction to the electromagnetic spectrum and then goes into great detail about the properties of light. Then it talks about how matter both creates and destroys radiation. Then it discusses how to interpret absorption and emission lines. The website ends with how astronomers use spectra to understand stars, galaxies, other objects in the universe.

Kaler, James

2004-07-16

9

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity.  

PubMed

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-? quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D; Gong, Qihuang

2013-01-01

10

Noise level and ultrasound spectra during burring.  

PubMed

The aim of this study was to evaluate the noise spectra of current dentistry equipment during normal work at the dental clinic and in the laboratory. In the study, noise was measured during the dental treatment of seven patients at a dental clinic and also in the acoustics laboratory, where working noise was simulated by drilling a polyacetal plate. All samples were analyzed in audible and ultrasonic areas in the one-third octave bands of 20-80,000 Hz. The measuring instruments used were B&K 4135 microphones, B&K 2633 preamplifiers, the B&K 2811 multiplexer, and the B&K 2133 real-time analyzer with the ZT 0318 high-frequency expansion unit. In the in situ measurements, the A-weighted sound pressure level was occasionally over 85 dB(A), and the equivalent continuous A-weighted sound pressure level, L(Aeq), was 76 dB(A). The noise level was most powerful in the one-third octave band of 40,000 Hz, where it was 74 dB. In laboratory measurements, the noise levels of the air-turbine and the micromotor hand pieces (n=16) were also most powerful in the one-third octave band of 40,000 Hz, where they were 80-89 dB. The L(Aeq) of the different micromotor handpieces (n=6) varied between 76 dB(A) and 77 dB(A), and the L(Aeq) of the turbine hand pieces (n=10) varied between 77 dB(A) and 82 dB(A). The noise of the drills is most powerful in the high frequencies, so using hearing protectors, it is possible that speech communication improves because the protectors attenuate high frequencies more than low frequencies. The very light protectors give sufficient protection against the drilling noise. PMID:12271344

Sorainen, E; Rytkönen, E

2002-09-01

11

Catalogue of Dynamic Electromagnetic Spectra Observed with Callisto and Phoenix - 3  

NASA Astrophysics Data System (ADS)

This catalog demonstrates dynamic electromagnetic spectra observed by Callisto radio spectrometers. In this first part natural spectra are presented while in the second part in the next SARA journal we concentrate on artificial (man-made) spectra. This catalog shall help the amateur to detect and identify weak flares in highly interfered spectra. In addition to their role in the e-Callisto solar radio spectrometer network, Callisto spectrometers have proven to be a cheap and reliable instrument for radio frequency monitoring of terrestrial interference. Information on e-Callisto may be found at http://www.e-callisto.org/. Technical information on Phoenix-3 Fast Fourier Transform spectrometer may be found at http://soleil.i4ds.ch/solarradio/data/Description/phoenix3.pdf

Monstein, Christian

2012-12-01

12

An Electromagnetic Resonance Circuit for Liquid Level Detection  

ERIC Educational Resources Information Center

Electromagnetic resonators are often used to detect foreign materials. Here we present a simple experiment for the measurement of liquid level. The resonator, consisting of a coil and a capacitor, is brought to resonance by an external magnetic field source, and the corresponding resonance frequency is determined using Fourier analysis combined…

Hauge, B. L.; Helseth, L. E.

2012-01-01

13

Electromagnetically induced blazed grating at low light levels  

SciTech Connect

We propose a scheme for inducing a blazed transmission grating in a four-level, N-type atomic medium under electromagnetically induced transparency (EIT). The blazed grating relies on the giant Kerr nonlinearity that the atomic medium exhibits under EIT. The grating is created using an intensity mask in one of the driving optical fields and only weak fields with intensities below saturation level are involved. Diffraction efficiencies of a resonant probe beam close to 100% are predicted.

Carvalho, Silvania A.; Araujo, Luis E. E. de [Instituto de Fisica 'Gleb Wataghin', Universidade Estadual de Campinas, 13083-859 Campinas, Sao Paulo (Brazil)

2011-05-15

14

Three-dimensional electromagnetic strong turbulence. I. Scalings, spectra, and field statistics  

SciTech Connect

The first fully three-dimensional (3D) simulations of large-scale electromagnetic strong turbulence (EMST) are performed by numerically solving the electromagnetic Zakharov equations for electron thermal speeds {nu}{sub e} with {nu}{sub e}/c{>=}0.025. The results of these simulations are presented, focusing on scaling behavior, energy density spectra, and field statistics of the Langmuir (longitudinal) and transverse components of the electric fields during steady-state strong turbulence, where multiple wave packets collapse simultaneously and the system is approximately statistically steady in time. It is shown that for {nu}{sub e}/c > or approx. 0.17 strong turbulence is approximately electrostatic and can be explained using the electrostatic two-component model. For v{sub e}/c > or approx. 0.17 the power-law behaviors of the scalings, spectra, and field statistics differ from the electrostatic predictions and results because {nu}{sub e}/c is sufficiently high to allow transverse modes to become trapped in density wells. The results are compared with those of past 3D electrostatic strong turbulence (ESST) simulations and 2D EMST simulations. For number density perturbations, the scaling behavior, spectra, and field statistics are shown to be only weakly dependent on {nu}{sub e}/c, whereas the Langmuir and transverse scalings, spectra, and field statistics are shown to be strongly dependent on {nu}{sub e}/c. Three-dimensional EMST is shown to have features in common with 2D EMST, such as a two-component structure and trapping of transverse modes which are dependent on {nu}{sub e}/c.

Graham, D. B.; Robinson, P. A.; Cairns, Iver H. [School of Physics, University of Sydney, New South Wales 2006 (Australia); Skjaeraasen, O. [ProsTek, Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway)

2011-06-15

15

Reemission spectra and interference effects at the interaction of multiatomic targets with ultrashort electromagnetic pulses  

NASA Astrophysics Data System (ADS)

The processes of reemission of ultrashort electromagnetic pulses by linear chains consisting of isolated multielectron atoms have been considered. The developed method makes it possible to accurately take into account the spatial inhomogeneity of the field of an ultrashort pulse and the momenta of photons in reemission processes. The angular distributions of reemission spectra have been obtained for an arbitrary number of atoms in a chain. It has been shown that the interference of the photon emission amplitudes leads to the appearance of characteristic "diffraction" maxima. The results allow standard generalization to the cases of rescattering from two-dimensional (graphene-like) and three-dimensional lattices, as well as to the case of the inclusion of thermal vibrations of the atoms of lattices.

Matveev, V. I.; Matrasulov, D. U.

2013-01-01

16

Features of the broad upshifted structure in stimulated electromagnetic emission spectra  

NASA Astrophysics Data System (ADS)

We present experimental results concerning features of the broad upshifted structure (BUS) in stimulated electromagnetic emission spectra, generated in the ionospheric F region plasma by a powerful electromagnetic wave. The BUS is observed for pump frequencies far from electron cyclotron harmonics. Modification experiments, using O-mode HF pump waves, were conducted at the SURA heating facility (56°N, 44°E, Nizhny Novgorod, Russia). We investigated the BUS properties for pump frequencies ranging from the third to the sixth electron cyclotron harmonic, concentrating on the dependence of (1) the BUS spectral features on pump frequency and power and (2) the BUS temporal evolution under different ionospheric conditions with and without additional heating of the ionosphere by another pump wave. We find (1) that the frequency range of BUS generation depends on the gyroharmonic mode number, becoming narrower with increasing mode number, and (2) that the BUS is produced in the vicinity of the upper hybrid resonance layer, located typically a few kilometers below the pump wave reflection height. An important result is that small-scale striations, being produced concurrently with the upper hybrid plasma waves due to the thermal parametric instability, do not play a crucial role for the BUS evolution. A possible relationship of the BUS to gyroharmonic features is discussed.

Frolov, V. L.; Ermakova, E. N.; Kagan, L. M.; Komrakov, G. P.; Sergeev, E. N.; Stubbe, P.

2000-09-01

17

Electromagnetic model order reduction for system-level modeling  

Microsoft Academic Search

Reduced-order modeling of an electromagnetic system is understood as the approximation of a continuous or discrete model of the system by one of substantially lower order, yet capable of capturing the electromagnetic behavior of the original one with sufficient engineering accuracy. Specific methodologies for model order reduction of distributed electromagnetic systems are discussed in this paper. It is shown that

Andreas C. Cangellaris; Mustafa Celik; Soheila Pasha; Li Zhao

1999-01-01

18

Patterns of energy levels and spectra for polyatomic molecules  

SciTech Connect

Laser spectroscopy has revealed a remarkable intricacy in the rotational, vibrational, and electronic energy levels for polyatomic molecules. The infrared spectra of SF/sub 6/, CF/sub 4/, and related molecules contain several levels of structure on top of structure which resembles a fractal in some ways. The purpose of this article will be to exhibit some of this structure and introduce the simplest theoretical interpretations of it which are presently available.

Harter, W.G.

1983-01-01

19

Levelling of helicopter-borne frequency-domain electromagnetic data  

NASA Astrophysics Data System (ADS)

For about three decades helicopter-borne electromagnetic (HEM) measurements have been used to reveal the resistivity distribution of the upper one hundred metres of the earth's subsurface. HEM systems record secondary fields, which are 3-6 orders of magnitude smaller than the transmitted primary fields. As both the primary fields and the secondary fields are present at the receivers, well-designed bucking coils are often used to reduce the primary fields at the receivers to a minimum. Remaining parts of the primary fields, the zero levels, are generally corrected by subtracting field values recorded at high altitudes (standard zero levelling) or estimated from resistivities of neighbouring lines or from resistivity maps (advanced zero levelling). These zero-levelling techniques enable the correction for long-term, quasi-linear instrumental drift. Short-term variations caused by temperature changes due to altitude variations, however, cannot be completely corrected by this procedure resulting in stripe patterns on thematic maps. Statistical methods and/or 2-D filter techniques called statistical levelling (tie-line levelling) and empirical levelling (microlevelling), respectively, used to correct stripe patterns in airborne geophysical data sets are, in general, not directly applicable to HEM data. Because HEM data levelling faces the problem that the parameter affected by zero-level errors, the secondary field, differs from the parameter generally levelled, the apparent resistivity. Furthermore, the dependency of the secondary field on both the resistivity of the subsurface and the sensor altitude is strongly nonlinear. A reasonable compromise is to microlevel both half-space parameters: apparent resistivity and apparent depth, followed by a recalculation of the secondary field components based on the half-space parameters levelled. Advantages and disadvantages of the diverse levelling techniques are discussed using a HEM data set obtained in a hilly region along the Saale River between the cities of Saalfeld and Jena in central Germany. It turns out from a comparison of apparent resistivity and apparent depth maps derived from levelled HEM data that manually advanced zero levelling of major level errors and automatic microlevelling of remaining minor level errors yield the best results.

Siemon, Bernhard

2009-03-01

20

Electromagnetism.  

National Technical Information Service (NTIS)

This program demonstrates the characteristics of electromagnetism with iron filings and a compass. It shows the left-hand rule for determining current flow in an electromagnet. It illustrates the use of a dot and a cross to designate current flow.

1994-01-01

21

Quantum noise of an electromagnetically controlled two level system  

NASA Astrophysics Data System (ADS)

A coherent control of a spin is limited by both the decoherence due to coupling with the environment and noise coming from the quantized control. A quantum noise study is particularly important in fault tolerant quantum computation where a very high fidelity is demanded. Here, we present a time evolution study of a two level system interacting with a laser pulse and the electromagnetic vacuum based on the multimode Jaynes- Cummings model. We develop a diagrammatic formalism in which one can easily identify the coherent Rabi oscillation of the TLS and its relaxation from corresponding diagrams. In the small time limit (tT1), where the noise level is small but still an issue to fault tolerant quantum computing, this method gives a quantitative evaluation of the quantum noise of the TLS under an optical control with an arbitrary pulse shape. Furthermore, this approach can be naturally extended from the Markovian to the non-Markovian regime, resulting in dynamics different from that obtained in the optical Bloch analysis. All these calculations are done without any stochastic assumption.

Chan, Ching-Kit; Sham, L. J.

2011-03-01

22

Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.  

PubMed

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices. PMID:10608306

Harris, C; Boivin, W; Boyd, S; Coletta, J; Kerr, L; Kempa, K; Aronow, S

2000-01-01

23

GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra  

SciTech Connect

The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

Winn, W.G.

1999-07-28

24

Electromagnets  

NSDL National Science Digital Library

This is an activity about the properties of electromagnets, which is a crucial underpinning for understanding how magnetic fields are generated in nature, in the surface of the Sun, and in the interior of Earth. Learners will create an electromagnet by letting an electric current flow through a wire to generate a magnetic field, which is then detected using a compass. This activity requires a thin insulated wire, pencil, battery, compass and paper clips. This is Activity 2 of the Magnetism and Electromagnetism teachers guide.

25

Utilization of Target Scattering to Measure High-Level Electromagnetic Fields: The MICHELSON Method  

Microsoft Academic Search

The intention of this paper is to present the instantaneous electromagnetic field measurement by signature of a neutral object (MICHELSON) method. The MICHELSON method is relatively new and enables the measurement of high-level electromagnetic fields from the utilization of a target. The incident field scattering on the target allows us to move the field measurement to a new location where

Stephane Vauchamp; Michèle Lalande; Joël Andrieu; Bernard Jecko; Jean Louis Lasserre; Laurent Pecastaing; Baptiste Cadilhon

2010-01-01

26

The Permittivity and Permeability of Solid, Granular, Electromagnetic Materials: a Critical Examination and Extension of Current Method for Spectra Calculation  

NASA Astrophysics Data System (ADS)

This work examines and extends the present analytic technique for calculating the permeability and permittivity spectra of composite materials. It addresses the relationship between grain properties and their sizes and the permeability and permittivity spectra of polycrystalline material. The work begins by considering the interior and exterior fields about a sphere of arbitrary permittivity and permeability illuminated by an incident electromagnetic plane wave, over a frequency range where the product of the wavevector 'k' and sphere radius 'a' is always small. The fields are found using two methods: the standard multipolar method and Stevenson's method. An in-depth comparison between the two methods is made. Stevenson's method can only be used when the product of the internal wave vector k _{rm i} and sphere radius, equal to ka(muvarepsilon) ^{1/2}, is small, however the multipolar method has no such constraint. The scattered multipolar fields about a single sphere are related to the polarizability of an ordered congregation of such spheres. Using the Clausius-Mossotti relation the effective permeability and permittivity spectra of a congregate polycrystalline material is determined for arbitrary size, permittivity, and permeability of the individual, identical spheres making up the composite. Although we consider the spectra over a range where the product ka is kept small, typically less than one-tenth, the product k_{rm i}a can be quite large. The theory developed predicts many different spectra types; including complex permittivity and permeability spectra that have been measured experimentally and explained by either including multiple sources or statistical weighing. The theory presented here predicts both the 'classical' and 'anomolous' spectra that have been experimentally measured, without employing multiple additive sources. It also predicts the more difficult, conglomerate spectra that have been measured for which no theory has been put forth to explain. Results presented here suggest that the permeability and permittivity spectra of composite materials, considered as an ordered array of uniform spheres, can be simply explained as the manifestations of electromagnetic boundary conditions and dimensional effects of the size to wavelength ratio.

Grimes, Craig Alan

27

Analysis of micro-Raman spectra combined with electromagnetic simulation and stress simulation for local stress distribution in Si devices  

NASA Astrophysics Data System (ADS)

We have developed a Raman simulation method using a finite-difference time-domain electromagnetic simulation and a finite element method stress simulation for precise local stress analysis of Si devices. This method accounts for the modification of light distribution by the sample structure, which significantly affects the Raman spectra near a metal gate structure with high refractive index and extinction coefficient. The precise stress estimation by this method is verified by analyzing polarized UV Raman measurements of a metal-oxide semiconductor field-effect transistor structure with a metal gate.

Tada, Tetsuya; Poborchii, Vladimir; Kanayama, Toshihiko

2012-12-01

28

Electromagnets  

NSDL National Science Digital Library

In this activity, the students will complete the grand challenge and design an electromagnet to separate steel from aluminum for the recycler. In order to do this, students compare the induced magnetic field of an electric current with the magnetic field of a permanent magnet and must make the former look like the latter. They discover that looping the current produces the desired effect and find ways to further strengthen the magnetic field.

Vu Bioengineering Ret Program

29

Dynamics of electronic transitions and reemission spectra of attosecond electromagnetic pulses  

NASA Astrophysics Data System (ADS)

The processes of reemission of attosecond electromagnetic pulses by systems in nonstationary states have been considered. The probabilities of the reemission of attosecond electromagnetic pulses at the resonance charge exchange of a proton on a hydrogen atom and at the decay of a quasistationary state, as well as the probabilities of the reemission of attosecond pulses by a system in a resonance external field, have been calculated as examples. The developed method can be applied to more complex targets, including targets in the collision state, and to various chemical reactions.

Matveev, V. I.; Makarov, D. N.

2014-05-01

30

Levelling of helicopter-borne frequency-domain electromagnetic data  

Microsoft Academic Search

For about three decades helicopter-borne electromagnetic (HEM) measurements have been used to reveal the resistivity distribution of the upper one hundred metres of the earth's subsurface. HEM systems record secondary fields, which are 3–6 orders of magnitude smaller than the transmitted primary fields. As both the primary fields and the secondary fields are present at the receivers, well-designed bucking coils

Bernhard Siemon

2009-01-01

31

Relationships Between Complex Core Level Spectra and Materials Properties  

SciTech Connect

The XPS of many oxides are quite complex and there may be several peaks of significant intensity for each subshell. These peaks arise from many-electron effects, which normally are treated with configuration interaction (CI) wavefunctions where static correlation effects are taken into account. It is common to use semiempirical methods to determine the matrix elements of the CI Hamiltonian and there are few rigorous CI calculations where parameters are not adjusted to fit experiment. In contrast, we present, in the present work, theoretical XPS spectra obtained with rigorous CI wavefunctions for CeO2 where the XPS are especially complex; several different core levels are studied. This study uses an embedded CeO8 cluster model to represent bulk CeO2 and the relativistic CI wavefunctions are determined using four-component spinors from Dirac-Fock calculations. In particular, we examine the importance of interatomic many-body effects where there is a transfer of electrons from occupied oxygen 2p orbitals into empty cation orbitals as it is common to ascribe the complex XPS to this effect. We also contrast the importance of many-body charge-transfer effects for the isoelectronic cations of Ce4+ and La3+. The long-range goal of this work is to relate the XPS features to the nature of the chemical bonding in CeO2 and we describe our progress toward this goal.

Nelin, Constance J.; Bagus, Paul S.; Ilton, Eugene S.; Chambers, Scott A.; Kuhlenbeck, Helmut; Freund, Hans-Joachim

2010-12-01

32

Level Density Parameter: A Tool to Study the Particle Spectra  

SciTech Connect

The compound nucleus {sup 76}Kr* is formed in the heavy-ion fusion reactions by an asymmetric entrance channel {sup 12}C+{sup 64}Zn and the symmetric entrance channel {sup 31}P+{sup 45}Sc at the excitation energy of 75 MeV and angular momentum of 39 eta. Neutron energy spectra of the asymmetric system ({sup 12}C+{sup 64}Zn) at different angles are well described by the statistical model predictions using the normal value of the level density parameter a = A/8 MeV{sup -1}. However, in the case of the symmetric system ({sup 31}P+{sup 45}Sc), the statistical model interpretation of the data requires the change in the value of a = A/10 MeV{sup -1}. The delayed evolution of the compound system in case of the symmetric {sup 31}P+{sup 45}Sc system may lead to the formation of a temperature equilibrated dinuclear complex, which may be responsible for the neutron emission at higher temperature, while the protons and alpha particles are evap orated after neutron emission when the system is sufficiently cooled down and the higher lambda-values do not contribute in the formation of the compound nucleus for the symmetric entrance channel in case of charged particle emission.

Kumar, Ajay [Department of Physics, Banaras Hindu University, Varanasi-221005 (India); Kumar, A.; Singh, G.; Singh, Hardev; Govil, I. M. [Department of Physics, Panjab University, Chandigarh-160014 (India); Singh, R. P.; Kumar, Rakesh; Golda, K. S. [Inter University Accelerator Centre, New Delhi-110067 (India)

2010-04-30

33

Surface-enhanced Raman scattering spectra of adsorbates on Cu?O nanospheres: charge-transfer and electromagnetic enhancement.  

PubMed

Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu2O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu2O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor. Density functional theory (DFT) calculations suggested a charge transfer (CT) transition process between the molecules and the Cu2O nanospheres. Three-dimensional finite-difference time domain (3D-FDTD) simulations were conducted to map out the electromagnetic field around the Cu2O nanospheres. The experimental and simulation results have revealed the promise of the Cu2O nanospheres as a good SERS substrate and the prospect of using the SERS substrate as a valuable tool for in situ investigation and assay of the adsorption behavior on semiconductor surfaces. PMID:23435689

Jiang, Li; You, Tingting; Yin, Penggang; Shang, Yang; Zhang, Dongfeng; Guo, Lin; Yang, Shihe

2013-04-01

34

Electromagnetically induced transparency in a five-level {Lambda} system dominated by two-photon resonant transitions  

SciTech Connect

We study the steady optical response of a five-level atomic system in the parametric region where resonant two-photon transitions are much stronger than far-detuned single-photon transitions. We find that the concurrent absorption of two weak probe fields can be well suppressed in a narrow spectral region to attain electromagnetically induced transparency (EIT) via quantum destructive interference between different two-photon transition pathways. To gain a deeper insight into relevant physics, we adiabatically reduce this five-level system with trivial single-photon transitions into a three-level system with vanishing single-photon transitions by deriving an effective Hamiltonian. The two systems have almost the same two-photon absorption spectra exhibiting typical EIT features but are a little different in fine details. This means that most characteristics of two-photon quantum destructive interference are reserved after the adiabatic elimination approximation. In addition, we verify by numerical calculations that the two-photon EIT spectra are insensitive to the dipole-dipole interaction of cold Rydberg atoms when the uppermost level has a high principle quantum number.

Yan Dong [College of Physics, Jilin University, Changchun 130012 (China); School of Science, Changchun University, Changchun 130022 (China); Gao Jinwei; Bao Qianqian; Yang Hong; Wang Heng; Wu Jinhui [College of Physics, Jilin University, Changchun 130012 (China)

2011-03-15

35

A Two-Level Genetic Algorithm for Electromagnetic Optimization  

Microsoft Academic Search

Optimizing complex engineering problems may demand large computational efforts because of the use of numerical models. Global optimization can be established through the use of evolutionary algorithms, but may demand a prohibitive amount of computational time. In order to reduce the computational time, we incorporate in the global optimization procedures a physics-based fast coarse model. This paper presents a two-level

Guillaume Crevecoeur; Peter Sergeant; Luc Dupre; Rik Van de Walle

2010-01-01

36

A shape reconstruction method for electromagnetic tomography using adjoint fields and level sets  

Microsoft Academic Search

A two-step shape reconstruction method for electromagnetic (EM) tomography is presented which uses adjoint fields and level sets. The inhomogeneous background permittivity distribution and the values of the permittivities in some penetrable obstacles are assumed to be known, and the number, sizes, shapes, and locations of these obstacles have to be reconstructed given noisy limited-view EM data. The main application

Oliver Dorn; Eric L. Miller; Carey M. Rappaport

2000-01-01

37

Matter coupling to strong electromagnetic fields in two-level quantum systems with broken inversion symmetry.  

PubMed

We demonstrate theoretically the parametric oscillator behavior of a two-level quantum system with broken inversion symmetry exposed to a strong electromagnetic field. A multitude of resonance frequencies and additional harmonics in the scattered light spectrum as well as an altered Rabi frequency are predicted to be inherent to such systems. In particular, dipole radiation at the Rabi frequency appears to be possible. Since the Rabi frequency is controlled by the strength of the coupling electromagnetic field, the effect can serve for the frequency-tuned parametric amplification and generation of electromagnetic waves. Manifestation of the effect is discussed for III-nitride quantum dots with strong built-in electric field breaking the inversion symmetry. Terahertz emission from arrays of such quantum dots is shown to be experimentally observable. PMID:19257272

Kibis, O V; Slepyan, G Ya; Maksimenko, S A; Hoffmann, A

2009-01-16

38

Electromagnetic Radiography (EMR) for the detection of low-level chemical contamination in the ground  

Microsoft Academic Search

Electromagnetic Radiography (EMR)TM provides direct, high- resolution images of low-level chemical contamination in the ground at concentration levels in the parts-per-billion range ((mu) g\\/kg). This new sensor system can distinguish between dense, non-aqueous phase liquids (DNAPLs) and light, non- aqueous phase liquids (LNAPLs). Ionic chemicals can be distinguished from non-ionic chemicals, and dissolved-phase chemicals in the water table can be

Aka G. Finci; Daniel F. Stanfill

1999-01-01

39

Electromagnetically Induced Left Handedness in Optically Excited Four-Level Atomic Media  

Microsoft Academic Search

We show that left-handed properties can be electromagnetically induced in a general four-level atomic medium for a finite spectral range. We use an electric (magnetic) atomic transition as an electric (magnetic) resonator to modify the permittivity (permeability), both at the same frequency. The implementation of the four-level model is carried out in atomic hydrogen and neon. In each case the

Quentin Thommen; Paul Mandel

2006-01-01

40

Survey of ambient electromagnetic and radio-frequency interference levels in nuclear power plants  

SciTech Connect

This document reports the results of a survey of ambient electromagnetic conditions in representative nuclear power plants. The U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research engaged the Oak Ridge National Laboratory (ORNL) to perform these measurements to characterize the electromagnetic interference (EMI) and radio-frequency interference (RFI) levels that can be expected in nuclear power plant environments. This survey is the first of its kind, being based on long-term unattended observations. The data presented in this report were measured at eight different nuclear units and required 14 months to collect. A representative sampling of power plant conditions (reactor type, operating mode, site location) monitored over extended observation periods (up to 5 weeks) were selected to more completely determine the characteristic electromagnetic environment for nuclear power plants. Radiated electric fields were measured over the frequency range of 5 MHz to 8 GHz. Radiated magnetic fields and conducted EMI events were measured over the frequency range of 305 Hz to 5 MHz. Highest strength observations of the electromagnetic ambient environment across all measurement conditions at each site provide frequency-dependent profiles for EMI/RFI levels in nuclear power plants.

Kercel, S.W.; Moore, M.R.; Blakeman, E.D.; Ewing, P.D.; Wood, R.T.

1996-11-01

41

Influence of multi-level impurities on the dynamics of ultrashort electromagnetic pulses in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Based on Maxwell's equations, we study the propagation of an ultrashort electromagnetic pulse through an array of carbon nanotubes with multi-level impurities. The effective equation for the vector potential of the electromagnetic field is first derived analytically and then solved numerically. We subsequently analyze the dependence of the pulse shape on the parameters of the energy spectrum of impurities, and more precisely on the impurity levels. Our analysis predicts a significant decrease in the pulse amplitude during the transient, which is associated with the competitive effects of dispersion and other nonlinear effects. We also uncover the effects of the hopping integrals and band gap of deep impurities on the pulse tail decay.

Zhukov, Alexander V.; Bouffanais, Roland; Konobeeva, Natalia N.; Belonenko, Mikhail B.; George, Thomas F.

2014-05-01

42

Four-wave mixing in a three-level bichromatic electromagnetically induced transparency system  

SciTech Connect

We investigate the four-wave mixing (FWM) phenomenon in a three-level bichromatic electromagnetically induced transparency system. Theoretical results predict that the FWM will exhibit a multipeak structure under bichromatic coupling fields. The stronger the coupling fields are, the more FWM the peaks should exhibit. Results of an experiment carried out with cold {sup 87}Rb atoms in a magneto-optical trap agree with the theoretical prediction.

Yang, G. Q.; Xu, P. [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071 (China); Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071 (China); Graduate University, Chinese Academy of Sciences, Beijing 100049 (China); Wang, J.; Zhan, M. S. [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Wuhan 430071 (China); Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071 (China); Zhu Yifu [Department of Physics, Florida International University, Miami, Florida 33199 (United States)

2010-10-15

43

March 17 - 19, 2004: Low-level processing of proteomics spectra, Kevin Coombes  

Cancer.gov

Low-level processing of proteomics spectra Kevin Coombes Department of Biostatistics and Applied Mathematics UT M.D.Anderson Cancer Center Overview z Background and motivation z Description of data set for methodology development and testing z Wavelet

44

Extreme Ultraviolet Emission Spectra of Core-Excited Levels in Sodium and Magnesium.  

National Technical Information Service (NTIS)

Using a pulsed-hollow-cathode discharge, we have observed the emission spectra of core-excited levels of Na I and Mg II. Line identifications and implications for extreme ultraviolet lasers are discussed. Keywords: Extreme Ultraviolet Radiation; Sodium; M...

K. D. Pedrotti A. J. Mendelsohn R. W. Falcone J. F. Young S. E. Harris

1985-01-01

45

Propagation and modulation of Airy beams through a four-level electromagnetic induced transparency atomic vapor.  

PubMed

We study the propagation properties of an Airy beam through a four-level electromagnetic induced transparency (EIT) atomic vapor. The analytical expression for the Airy beam passing through the ABCD optical system of the EIT vapor is deduced and employed to analyze the propagation characteristics of the beam. It is shown that both the deflection position and the intensity of the Airy beam can be modulated by the Rabi frequency of the control light. Such a tunable optical behavior may have some potential applications in medicine science. PMID:22859083

Zhuang, Fei; Shen, Jianqi; Du, Xinyue; Zhao, Daomu

2012-08-01

46

Electromagnetically induced self-imaging in four-level atomic system.  

PubMed

In this paper, a special gradient-index electromagnetically induced transparency medium is induced with a Gaussian control field, which can be realized in a four-level ??Rb cold atomic cloud. Special directional self-imaging and imaging transforming properties are studied in this work. Simulated results show that a complex object can be imaged in the cold atoms, as the control field substituted with the elliptical Gaussian beam, then the self-imaging is directional, which has potental application in encryption. PMID:24663467

Wang, Feng; Wang, Chunfang; Cheng, Jing; Zhang, Dawei

2014-03-20

47

Electromagnetically induced transparency in cesium vapor with probe pulses on the single-photon level.  

PubMed

We perform electromagnetically induced transparency (EIT) experiments in cesium vapor with pulses on the single-photon level for the first time. This was made possible by an extremely large total suppression of the EIT coupling beam by 118 dB mainly due to a newly developed triple-pass planar Fabry-Pérot etalon filter. Slowing and shaping of single-photon light pulses as well as the generation of pulses suitable for quantum key distribution applications and testing of approaches for single photon storage is demonstrated. Our results extend single-photon EIT to the particularly interesting wavelength of the Cs D1 line. PMID:21230904

Höckel, David; Benson, Oliver

2010-10-01

48

Effect of strong electromagnetic fields on dilute-gas spectra: The three-level system  

Microsoft Academic Search

The effect of a strong perturbing radiation field on spectral lines is studied using an extension of the Kubo-Zwanzig-Fano relaxation formalism. The problem of a dilute gas interacting with a strong perturbing field and a weak probe field is solved, assuming a separation of collisional and radiative processes, by introducing a classical-field renormalization technique. The solution is formulated entirely in

Lewis Klein; Michel Giraud; Abraham Ben-Reuven

1974-01-01

49

Comparison between Trans-Cranial Electromagnetic Stimulation and Low-Level Laser on Modulation of Trigeminal Neuralgia.  

PubMed

[Purpose] To determine which of the transcranial electromagnetic stimulation or low level laser therapy is more effective in the treatment of trigeminal neuralgia of multiple sclerosis patients. [Methods] Thirty multiple sclerosis patients of both sexes participated in this study. The age of the subjects ranged from 40 to 60?years and their mean age was (56.4-6.6). Participants were randomly selected from Dental and Neurology Outpatient Clinics at King Khalid Hospital, Najran University, Saudi Arabia. Patients were randomly divided into two equal groups of 15. The Laser group received a low level laser therapy, 830?nm wavelength, 10?Hz and 15?min duration, while the Electromagnetic group received repetitive transcranial electromagnetic stimulation at a frequency of 10?Hz, intensity of 50 mA and duration of 20 minutes. Patients were assessed pre and post treatment for degree of pain using a numerical rating scale, maximal oral mouth opening using a digital calibrated caliper, masseter muscle tension using a tensiometer and a compound action potentials of masseter and temporalis muscles. [Results] There were significant improvements after treatment in both groups, with a significant difference between the Electromagnetic and Laser groups, in favor of the Electromagnetic group. [Conclusion] Repetitive transcranial electromagnetic stimulation at 10?Hz, 50 mA, and 20 minutes duration is more effective than low level laser therapy at reducing trigeminal pain, increasing maximum oral mouth opening, masseter and temporalis muscle tension in multiple sclerosis patients. PMID:24259883

Seada, Yasser Ibrahim; Nofel, Reda; Sayed, Hayam Mahmoud

2013-08-01

50

Emission spectra and intrinsic optical bistability in a two-level medium  

Microsoft Academic Search

Scattering of resonant radiation in a dense two-level medium is studied theoretically accounting for local field effects and renormalisation of the resonance frequency. Intrinsic optical bistability is viewed as switching between different spectral patterns of fluorescent light controlled by the incident field strength. Response spectra are calculated analytically for the entire hysteresis loop of atomic excitation. The equations to describe

M. G. Gladush; D. V. Kuznetsov; Vl. K. Roerich

2011-01-01

51

Revisiting the Valence-Band and Core-Level Photoemission Spectra of NiO  

NASA Astrophysics Data System (ADS)

We have reexamined the valence-band (VB) and core-level electronic structure of NiO by means of hard and soft x-ray photoemission spectroscopies. The spectral weight of the lowest energy state was found to be enhanced in the bulk sensitive Ni 2p core-level spectrum. A configuration-interaction model including a bound state screening has shown agreement with the core-level spectrum and off- and on-resonance VB spectra. These results identify the lowest energy states in the core-level and VB spectra as the Zhang-Rice (ZR) doublet bound states, consistent with the spin-fermion model and recent ab initio calculations within dynamical mean-field theory. The results indicate that the ZR character first ionization (the lowest hole-addition) states are responsible for transport properties in NiO and doped NiO.

Taguchi, M.; Matsunami, M.; Ishida, Y.; Eguchi, R.; Chainani, A.; Takata, Y.; Yabashi, M.; Tamasaku, K.; Nishino, Y.; Ishikawa, T.; Senba, Y.; Ohashi, H.; Shin, S.

2008-05-01

52

Revisiting the valence-band and core-level photoemission spectra of NiO.  

PubMed

We have reexamined the valence-band (VB) and core-level electronic structure of NiO by means of hard and soft x-ray photoemission spectroscopies. The spectral weight of the lowest energy state was found to be enhanced in the bulk sensitive Ni 2p core-level spectrum. A configuration-interaction model including a bound state screening has shown agreement with the core-level spectrum and off- and on-resonance VB spectra. These results identify the lowest energy states in the core-level and VB spectra as the Zhang-Rice (ZR) doublet bound states, consistent with the spin-fermion model and recent ab initio calculations within dynamical mean-field theory. The results indicate that the ZR character first ionization (the lowest hole-addition) states are responsible for transport properties in NiO and doped NiO. PMID:18518558

Taguchi, M; Matsunami, M; Ishida, Y; Eguchi, R; Chainani, A; Takata, Y; Yabashi, M; Tamasaku, K; Nishino, Y; Ishikawa, T; Senba, Y; Ohashi, H; Shin, S

2008-05-23

53

GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA  

Microsoft Academic Search

The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or

Winn

1999-01-01

54

Cosmic ray muon spectra at sea-level up to 10 TeV  

NASA Astrophysics Data System (ADS)

The momentum spectra of muons in cosmic radiation have been measured with high statistics at sea-level with the DEIS spectrometer by a Kiel-Tel Aviv collaboration. The apparatus consists of solid iron magnets and spark chambers with magnetostrictive readout. The momentum spectra and the charge ratio of muons are obtained in the momentum range from GeV/ c to 10 TeV/ c in the angular range 78°-90°. The production spectrum was derived from the measured muon intensities.

Allkofer, O. C.; Bella, G.; Dau, W. D.; Jokisch, H.; Klemke, G.; Oren, Y.; Uhr, R.

1985-09-01

55

Electromagnetic bias of 36-GHz radar altimeter measurements of MSL. [Mean Sea Level  

NASA Technical Reports Server (NTRS)

The data reduction techniques used to determine the magnitude of electromagnetic (EM) bias in radar altimeter measurements of mean sea level (MSL) area described. Particular attention is given to the bias reduction scheme developed specifically for the Surface Contour Radar (SCR) instrument of the Ocean Topography Experiment (TOPEX). The SCR makes it possible to determine the amount of the backscattered power due to EM reflectance per unit area by measuring both the return power and elevation. Variations of backscattered power for different sea states are determined as a function of displacement of the MSL. On the basis of the recent SCR observations from aircraft, a standard error due to EM bias is predicted for MSL measurements performed with a satellite altimeter radar operating at a frequency of 36 GHz. The obtained standard error was 1 percent for regions with waves 1.9-5.5 meters in height.

Walsh, E. J.; Hancock, D. W., III; Hines, D. E.; Kenney, J. E.

1984-01-01

56

Absorption spectra of pulse-train-excited sodium two-level atoms  

NASA Astrophysics Data System (ADS)

The steady-state absorption of a beam of sodium atoms irradiated by a train of pulses from a mode-locked dye laser has been measured. The sodium atoms were prepared as two-level systems by optical pumping with a two-mode laser. Absorption spectra on the 589.0-nm D2 line were recorded over 20 GHz with a frequency-stabilized, tunable, mode-locked dye laser having a bandwidth of 3.7 GHz and a mode spacing of 82 MHz. The laser-pulse profile was determined from the spectral profile assuming transform-limited pulses and was incorporated in theoretical calculations of excitation spectra obtained by numerical integration of the optical Bloch equations. By comparison of measured absorption spectra and theoretical excitation spectra the validity of the weak-field solution as well as the predicted saturation behavior were fully verified by the experimental results. For the highest level of irradiation applied, the laser pulses were identified as pi pulses.

Krüger, E.

1995-01-01

57

Electromagnetically induced absorption due to transfer of population in degenerate two-level systems  

NASA Astrophysics Data System (ADS)

We predict the occurrence of electromagnetically induced absorption (EIA) in cycling degenerate two-level transitions where Fe=Fg+1 and Fg>0 , interacting with pump and probe lasers with the same polarization. The EIA is due to transfer of population (TOP) between the Zeeman levels of the ground hyperfine state, rather than transfer of coherence (TOC) which occurs for perpendicularly polarized lasers. We model EIA-TOP using a double two-level system (TLS) which we compare with the four-level N system, which models EIA-TOC. When the pump intensity is low, both models give an EIA peak at line center. The effect of introducing phase-changing collisions is studied, in the presence and absence of Doppler broadening, for both the double TLS and N systems. In the presence of phase-changing collisions, the central EIA peaks are narrowed in both models and persist to higher pump Rabi frequencies than in the absence of collisions. In the double TLS, in the presence of Doppler broadening, the central EIA-TOP peak becomes narrower and does not develop a dip in its center, in contrast to the N system. The central dip that appears in the Doppler-broadened EIA-TOC spectrum can be wiped out by adding phase-changing collisions. We demonstrate that EIA-TOP can be obtained for realistic atomic transitions interacting with lasers that have the same polarization.

Goren, C.; Wilson-Gordon, A. D.; Rosenbluh, M.; Friedmann, H.

2004-10-01

58

Effects of electromagnetic fields on photophasic circulating melatonin levels in American kestrels.  

PubMed Central

Birds reproduce within electromagnetic fields (EMFs) from transmission lines. Melatonin influences physiologic and behavioral processes that are critical to survival, and melatonin has been equivocally suppressed by EMFs in mammalian species. We examined whether EMFs affect photophasic plasma melatonin in reproducing adult and fledgling American kestrels (Falco sparverius), and whether melatonin was correlated with body mass to explain previously reported results. Captive kestrel pairs were bred under control or EMF conditions for one (short-term) or two (long-term) breeding seasons. EMF exposure had an overall effect on plasma melatonin in male kestrels, with plasma levels suppressed at 42 days and elevated at 70 days of EMF exposure. The similarity in melatonin levels between EMF males at 42 days and controls at 70 days suggests a seasonal phase-shift of the melatonin profile caused by EMF exposure. Melatonin was also suppressed in long-term fledglings, but not in short-term fledglings or adult females. Melatonin levels in adult males were higher than in adult females, possibly explaining the sexually dimorphic response to EMFs. Melatonin and body mass were not associated in American kestrels. It is likely that the results are relevant to wild raptors nesting within EMFs. Images Figure 1

Fernie, K J; Bird, D M; Petitclerc, D

1999-01-01

59

Measurement of radiated electromagnetic field levels before and after a changeover to energy-efficient lighting.  

PubMed

An energy-efficient lighting retrofit at the Food and Drug Administration (FDA) Winchester Engineering and Analytical Center (WEAC) presented the opportunity to measure the electromagnetic (EM) environments in several rooms before and after changing the fluorescent lighting systems and to compare the changes in EM fields with the proposed standard EM immunity levels. Three rooms, representing the types of work areas in the laboratory, were selected and measured before and after the lighting changeover. Electric and magnetic field measurements were taken in the extremely low frequency (ELF), very low frequency (VLF), and radio frequency (RF) ranges of the EM spectrum. In 2 rooms, ELF electric fields were reduced and VLF and RF electric fields were increased as a result of the changeover to high-frequency fixtures. A third room received low-frequency, energy-efficient fixtures during this changeover, and this change resulted in only a slight increase of the ELF electric fields. The ELF magnetic fields were greatly reduced in 2 but only slightly reduced in the third room. No significant change was seen in VLF or RF magnetic fields for any of these rooms. Some field-strength measurements exceeded the proposed immunity levels recommended in the draft International Electrotechnical Commission standard IEC 60601-1-2 (rev. 2). The data show that increasing the separation distance from the fluorescent light fixtures greatly reduces the field-strength levels, limiting the potential for EM interference. PMID:11383307

Kerr, L N; Boivin, W S; Boyd, S M; Coletta, J N

2001-01-01

60

Emission spectra and intrinsic optical bistability in a two-level medium  

Microsoft Academic Search

Scattering of resonant radiation in a dense two-level medium is studied\\u000atheoretically with account for local field effects and renormalization of the\\u000aresonance frequency. Intrinsic optical bistability is viewed as switching\\u000abetween different spectral patterns of fluorescent light controlled by the\\u000aincident field strength. Response spectra are calculated analytically for the\\u000aentire hysteresis loop of atomic excitation. The equations to

M. G. Gladush; D. V. Kuznetsov; A. A. Panteleev; Vl. K. Roerich

2010-01-01

61

Modeling hyperspectral observations of vegetation fluorescence from photosystem level to top-of-atmosphere radiance spectra  

NASA Astrophysics Data System (ADS)

In support of the candidate ESA mission FLEX, models have been developed to simulate vegetation chlorophyll fluorescence and its observation on the level of single leaves, the canopy and from space. The Fluspect model is based on the PROSPECT leaf model and includes an additional module which calculates the excitation-fluorescence matrix for both sides of the leaf by means of an efficient doubling algorithm. Fluorescence spectra for white incident light, and of course the spectra of reflectance and transmittance, are computed as well. The FluorSAIL model is a numerical variant of SAIL which calculates top-of-canopy fluorescent radiance in the direction of viewing for given incident radiation spectra from the sun and the sky, obtained from the MODTRAN radiative transfer code. In a recent version called FluorSAIL3, high spectral resolution data (0.1 nm) from MODTRAN5 (beta) are used by the model to simulate observations by the candidate FLEX mission. The model computes the directional canopy reflectance with and without fluorescence for the given incident radiation spectra obtained from MODTRAN and the results have been used to evaluate several algorithms for the retrieval of fluorescence from the apparent reflectance signal. In this contribution emphasis will be on the detection of the fluorescence signal, the dependence of fluorescence observations on leaf chlorophyll content and other PROSPECT parameters, canopy structure, and observational conditions, including the properties of the atmosphere. In addition, some attention is paid to the definition of fluorescence quantum efficiencies at photosystem level, leaf level, and canopy level. This is important for the study of the relation between canopy fluorescence and actual photosynthesis. From the simulations it can be concluded that the interpretation of the fluorescence signal is complex, and probably the comparison of actual observations of spectra of fluorescence and reflectance with spectra simulated by a coupled chain of models such as Fluspect-FluorSAIL-MODTRAN will be of great help in drawing the correct conclusions from observations by a mission like FLEX.

Verhoef, W.

2011-12-01

62

Explaining Electromagnetic Plane Waves in a Vacuum at the Introductory Level  

ERIC Educational Resources Information Center

A typical introduction to electromagnetic waves in vacuum is illustrated by the following quote from an introductory physics text: "Maxwell's equations predict that an electromagnetic wave consists of oscillating electric and magnetic fields. The changing fields induce each other, which maintains the propagation of the wave; a changing electric…

Allred, Clark L.; Della-Rose, Devin J.; Flusche, Brian M.; Kiziah, Rex R.; Lee, David J.

2010-01-01

63

Emission spectra and intrinsic optical bistability in a two-level medium  

NASA Astrophysics Data System (ADS)

Scattering of resonant radiation in a dense two-level medium is studied theoretically accounting for local field effects and renormalisation of the resonance frequency. Intrinsic optical bistability is viewed as switching between different spectral patterns of fluorescent light controlled by the incident field strength. Response spectra are calculated analytically for the entire hysteresis loop of atomic excitation. The equations to describe the non-linear interaction of an atomic ensemble with light are derived from the Bogolubov-Born-Green-Kirkwood-Yvon hierarchy for reduced single particle density matrices of atoms and quantised field modes and their correlation operators. The spectral power of scattered light with separated coherent and incoherent constituents is obtained straightforwardly within the hierarchy. The formula obtained for emission spectra can be used to distinguish between possible mechanisms suggested to produce intrinsic bistability in experiments.

Gladush, M. G.; Kuznetsov, D. V.; Roerich, Vl. K.

2011-10-01

64

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals  

NASA Technical Reports Server (NTRS)

The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

Hartmann, S. R.; Happer, W.

1974-01-01

65

[Electronic spectra and energy levels analysis of Ho3+ in Cs2NaYF6].  

PubMed

The electronic spectra and energy levels of Ho3+ in Cs2NaYF6 were studied on basis of rare earth (RE) spectrum, quantum mechanics and crystal field theory. Detailed analysis on electronic absorption spectra at temperatures down to 10 K in the range of 4600-24,000 cm(-1) was carried out. The transitions, with zero phonon lines (ZPL) and abundant vibronic sidebands, from ground states to different excited states such as 5I(J); (J = 7, 6, 5, 4), 5F(S) (S = 5, 4, 3), 5G(P) (P = 6, 5) and (3)K8 were clearly observed. All the transitions have been assigned and 50 experimental crystal field levels have been obtained. The dataset has been investigated by standard f-shell program, which gave out the calculated energy levels and the corresponding empirical Hamiltonian parameters. The comparison of the energy levels and Hamiltonian parameters was made with that of Cs2NaYCl6 : Ho3+ as well. PMID:20939304

Zhou, Xian-ju; Ren, Chong-dan; Luo, Bin; Feng, Qiao-chun

2010-08-01

66

Occupational exposure of dentists to electromagnetic fields produced by magnetostrictive cavitrons alters the serum cortisol level  

PubMed Central

Objectives: Some studies indicate that dentistry is one of the job categories with high potential exposure to elevated levels of extremely low frequency magnetic fields. In spite of this, information on occupational exposure of dentists to these fields is scarce. Studies on other common sources of electromagnetic fields (EMFs) such as mobile base stations have shown alterations in the cortisol level following exposure of humans to these sources. The aim of this study is to compare the level of cortisol among dentists and dentistry students who are being occupationally exposed to EMFs emitted by magnetostrictive cavitrons (case group) and among their counterparts who are not being exposed to these fields (control group). Materials and Methods: In this case–control study, blood samples were collected from 41 dentists and dentistry students, 21 of whom were exposed to EMFs emitted by cavitrons as the case group and 20 who were not exposed as the control group, twice; i.e. before work (at 8:30–9:30 a.m.) and after work (11:30–12:30 a.m.). The samples were coded and the serum cortisol level was investigated using the ELISA method (Cortisol AccuBind ELISA Kits). Results: The serum cortisol level of dentists and dental students in the morning (before starting the work) in the control group was 189.15 ± 110.70 (mean ± SD) whereas it was 157.77 ± 112.03 in those who were occupationally exposed to EMFs produced by the use of cavitrons. This difference was not statistically significant (P = 0.373). In contrast, the serum cortisol level of the participants in the noon (after stopping the work) in the control group was 136.25 ± 67.91 (mean ± SD) while it was 88.58 ± 52.83 in those who were occupationally exposed to EMFs produced by the use of cavitrons. This time, the observed difference was statistically significant (P = 0.016). In this light, while the difference between serum cortisol levels of dentists and dental students in the morning and after stopping the work was not statistically significant (P = 0.06), in the EMF-exposed group the cortisol level decreased significantly from 157.77 ± 112.03 in the morning to 88.58 ± 52.83 in the noon (P = 0.001). Conclusions: As far as we know, this is the first study that evaluated the effect of occupational exposure of dentists to EMFs on their serum cortisol level. The EMFs produced by magnetostrictive cavitrons can decrease the serum cortisol level in dentists. As cortisol plays an important role in blood pressure regulation, cardiovascular, and immune system function, a low cortisol level may threaten health. More studies are needed to clearly understand the effects of EMFs emitted by magnetostrictive cavitron on the level of stress hormones. As some studies have shown that exposure to EMFs has no effect on the cortisol level, whereas other studies reported either an increase or a decrease in the cortisol level, it can be concluded that the effects of exposure to EMFs may occur only at specific absorbed energies or energy absorption rates (usually known as window) similar to that exists in the case of exposure to the low doses of ionizing radiations.

Mortazavi, S. M. J.; Vazife-Doost, S.; Yaghooti, M.; Mehdizadeh, S.; Rajaie-Far, A.

2012-01-01

67

Chronic Electromagnetic Exposure at Occupational Safety Level Does Not Affect the Metabolic Profile nor Cornea Healing after LASIK Surgery  

PubMed Central

LASIK eye surgery has become a very common practice for myopic people, especially those in the military. Sometimes undertaken by people who need to keep a specific medical aptitude, this surgery could be performed in secret from the hierarchy and from the institute medical staff. However, even though the eyes have been previously described as one of the most sensitive organs to electromagnetic fields in the human body, no data exist on the potential deleterious effects of electromagnetic fields on the healing eye. The consequences of chronic long-lasting radar exposures at power density, in accordance with the occupational safety standards (9.71?GHz, 50?W/m2), were investigated on cornea healing. The metabolic and clinical statuses after experimental LASIK keratotomy were assessed on the different eye segments in a New Zealand rabbit model. The analysis methods were performed after 5 months of exposure (1?hour/day, 3 times/week). Neither clinical or histological examinations, nor experimental data, such as light scattering, 1H-NMR HRMAS metabolomics, 13C-NMR spectra of lipidic extracts, and antioxidant status, evidenced significant modifications. It was concluded that withdrawing the medical aptitude of people working in electromagnetic field environments (i.e., radar operators in the navy) after eye surgery was not justified.

Dabouis, Vincent; Gentilhomme, Edgar; Vignal, Rodolphe; Bourbon, Frederic; Fauvelle, Florence; Debouzy, Jean-Claude

2014-01-01

68

Chronic Electromagnetic Exposure at Occupational Safety Level Does Not Affect the Metabolic Profile nor Cornea Healing after LASIK Surgery.  

PubMed

LASIK eye surgery has become a very common practice for myopic people, especially those in the military. Sometimes undertaken by people who need to keep a specific medical aptitude, this surgery could be performed in secret from the hierarchy and from the institute medical staff. However, even though the eyes have been previously described as one of the most sensitive organs to electromagnetic fields in the human body, no data exist on the potential deleterious effects of electromagnetic fields on the healing eye. The consequences of chronic long-lasting radar exposures at power density, in accordance with the occupational safety standards (9.71?GHz, 50?W/m(2)), were investigated on cornea healing. The metabolic and clinical statuses after experimental LASIK keratotomy were assessed on the different eye segments in a New Zealand rabbit model. The analysis methods were performed after 5 months of exposure (1?hour/day, 3 times/week). Neither clinical or histological examinations, nor experimental data, such as light scattering, (1)H-NMR HRMAS metabolomics, (13)C-NMR spectra of lipidic extracts, and antioxidant status, evidenced significant modifications. It was concluded that withdrawing the medical aptitude of people working in electromagnetic field environments (i.e., radar operators in the navy) after eye surgery was not justified. PMID:24757560

Crouzier, David; Dabouis, Vincent; Gentilhomme, Edgar; Vignal, Rodolphe; Bourbon, Fréderic; Fauvelle, Florence; Debouzy, Jean-Claude

2014-01-01

69

Multisite optical spectra and energy levels of trivalent thulium ions in yttrium scandium gallium garnet  

NASA Astrophysics Data System (ADS)

Intrinsic structural disorder in scandium-substituted garnets, attributed to mixed occupancy of certain sites in the crystal lattice by different cations, has direct consequences for the optical spectra of rare-earth activator ions dispersed over multiple sites. In trivalent thulium-doped Y-Sc-Ga garnet (Tm(3+):YSGG), site-selective laser excitation spectra reveal the presence of Tm(3+) ions in regular D2 sites, disturbed regular sites, and in octahedral C(3i) sites. Absorption spectra obtained at 4 K between 0.26 and 1.85 micron are broader than those observed in more ordered crystal hosts and include structure attributed to Tm(3+) ions in sites of other than D2 symmetry. A crystal-field splitting calculation was carried out in which a parametrized Hamiltonian (including Coulombic, spin-orbit, and crystal-field terms for Tm(3+) ions in D2 symmetry) was diagonalized for all manifolds of the Tm(3+) (4f exp 12) configuration. The rms deviation between 52 experimental and calculated Stark levels of Tm(3+) in regular D2 sites was 5/cm.

Seltzer, Michael D.; Gruber, John B.; Hills, Marian E.; Quarles, Gregory J.; Morrison, Clyde A.

1993-08-01

70

Magnetic breakdown and Landau level spectra of a tunable double-quantum-well Fermi surface  

SciTech Connect

By measuring longitudinal resistance, the authors map the Landau level spectra of double quantum wells as a function of both parallel (B{sub {parallel}}) and perpendicular (B{sub {perpendicular}}) magnetic fields. In this continuously tunable highly non-parabolic system, the cyclotron masses of the two Fermi surface orbits change in opposite directions with B{sub {parallel}}. This causes the two corresponding ladders of Landau levels formed at finite B{sub {perpendicular}} to exhibit multiple crossings. They also observe a third set of landau levels, independent of B{sub {parallel}}, which arise from magnetic breakdown of the Fermi surface. Both semiclassical and full quantum mechanical calculations show good agreement with the data.

Simmons, J.A.; Harff, N.E.; Lyo, S.K.; Klem, J.F. [Sandia National Labs., Albuquerque, NM (United States); Boebinger, G.S.; Pfeiffer, L.N.; West, K.W. [Lucent Technologies, Murray Hill, NJ (United States). Bell Labs.

1997-12-31

71

Investigation of the levels of electromagnetic radiation generated by wind turbines.  

National Technical Information Service (NTIS)

The issue of electromagnetic interference is arising with some regularity as various wind energy projects throughout the UK reach the stage where local authority planning approval is sought. To many of the parties involved, wind turbines represent an unkn...

C. A. Morgan

1992-01-01

72

Effects of vibrational motion on core-level spectra of prototype organic molecules  

SciTech Connect

A computational approach is presented for prediction and interpretation of core-level spectra of complex molecules. Applications are presented for several isolated organic molecules, sampling a range of chemical bonding and structural motifs. Comparison with gas phase measurements indicate that spectral lineshapes are accurately reproduced both above and below the ionization potential, without resort to ad hoc broadening. Agreement with experiment is significantly improved upon inclusion of vibrations via molecular dynamics sampling. We isolate and characterize spectral features due to particular electronic transitions enabled by vibrations, noting that even zero-point motion is sufficient in some cases.

Uejio, Janel S.; Schwartz, Craig P.; Saykally, Richard J.; Prendergast, David

2008-08-21

73

Observation of Squeezing in the Phase-Dependent Fluorescence Spectra of Two-Level Atoms  

NASA Astrophysics Data System (ADS)

We observe squeezing in the phase-dependent fluorescence spectra of two-level atoms that are coherently driven by a near-resonant laser field in free space. In contrast to previous predictions that emphasized the in- and out-of-phase quadratures, we find that maximum squeezing occurs for homodyne detection at a phase near +/-45? relative to the exciting field. A new physical picture of phase-dependent noise is developed that incorporates quantum collapses into a Bloch vector model and yields a very simple form for the complete squeezing spectrum.

Lu, Z. H.; Bali, S.; Thomas, J. E.

1998-10-01

74

Binding and release of brain calcium by low-level electromagnetic fields: A review  

NASA Astrophysics Data System (ADS)

Evidence has accumulated that sensitivity of brain tissue to specific weak oscillating electromagnetic fields occurs in the absence of significant tissue heating (less than 0.1°C). This review focuses on the ‘windowed’ character of sensitivities of calcium binding and electrical activity in brain tissue to low-frequency modulation and intensity characteristics of impressed RF fields. ELF fields decrease calcium efflux from isolated chick and cat cerebral tissue by about 15% only in narrow amplitude and frequency ‘windows,’ between 6 and 20 Hz and between 10 and 100 V/m (approximate tissue gradient, 10-7 V/cm). VHF (147 MHz) and UHF (450 MHz) fields increase calcium efflux from isolated chick brain by about 15% when amplitude modulated between 6 and 20 Hz, but only for incident fields in the vicinity of 1.0 mW/cm2. We have now shown that this increased efflux in response to 16-Hz amplitude-modulated 450-MHz, 0.75-mW/cm2 field exposure is insensitive to variations in calcium concentration from 0 to 4.16 mM in the testing solution but is enhanced by addition of hydrogen ions (0.108 mM 0.1 N HCl) and inhibited in the absence of normal bicarbonate ion levels (2.4 mM). In the presence of lanthanum ions (2.0 mM), which block transmembrane movement of calcium, exposure to these EM fields decreases the 45Ca2 + efflux. Low-frequency gradients may be transduced in a specific class of extracellular binding sites, normally occupied by calcium ions and susceptible to competitive hydrogen ion binding. Transductive coupling may involve coherent charge states between anionic sites on membrane surface glycoproteins, with longrange cooperative interactions triggered by weak extracellular electric fields. Proton ‘tunneling’ may occur at boundaries between coherent and noncoherent charge zones.

Adey, W. R.; Bawin, S. M.

75

Pulse electromagnetic fields effects on serum E2 levels, chondrocyte apoptosis, and matrix metalloproteinase-13 expression in ovariectomized rats  

Microsoft Academic Search

Observe pulse electromagnetic fields (PEMFs) effects on ovariectomized (OVX) rats, to study the mechanisms of PEMFs therapy\\u000a for postmenopausal osteoarthritis. Forty-eight female rats were exposed to PEMFs (PEMFs group), administrated E2 and placebo\\u000a PEMFs (E group), or were treated with placebo PEMFs (OVX and Sham groups). The treatment duration was 30 days after which\\u000a serum E2 levels, chondrocyte morphology, chondrocyte apoptosis

QingLu Luo; Sha-Sha Li; ChengQi He; HongChen He; Lin Yang; Li Deng

2009-01-01

76

Explaining Electromagnetic Plane Waves in a Vacuum at the Introductory Level  

NASA Astrophysics Data System (ADS)

A typical introduction to electromagnetic waves in vacuum is illustrated by the following quote from an introductory physics text: ``Maxwell's equations predict that an electromagnetic wave consists of oscillating electric and magnetic fields. The changing fields induce each other, which maintains the propagation of the wave; a changing electric field induces a magnetic field, and a changing magnetic field induces an electric field.''1 Students' intuition, developed from repeatedly solving simple problems involving Faraday's law in an introductory physics course, can lead them to expect the electric and magnetic waves to be out of phase, in contradiction to physical reality as described by Maxwell's equations. Below, we present the type of common Faraday's law problem that promotes this cognitive pitfall, and we suggest an approach that we believe leads to a deeper, more correct student understanding of electromagnetic waves.

Allred, Clark L.; Della-Rose, Devin J.; Flusche, Brian M.; Kiziah, Rex R.; Lee, David J.

2010-03-01

77

Spectra and energy levels of Yb{sup 3+} in AlN  

SciTech Connect

We report on the crystal-field energy levels calculation of Yb{sup 3+} ions in an AlN host using crystal-field theory. Cathodoluminescence spectra of AlN grown by molecular beam epitaxy on Si (0001) substrate and doped by implantation with ytterbium (Yb) ions were critically examined assuming that Yb{sup 3+} ions are involved in different sites. The comparison between the emission spectra of Yb{sup 3+} ions in the GaN and AlN indicates the presence of some similarities between the lattice locations of Yb{sup 3+} ions in these hosts. We demonstrate that assuming the existence of a substitutional Yb{sub Al(Ga)} site and a V{sub N}-Yb complex defect in AlN (GaN) lattice, a good agreement between the measured and calculated energy values of Yb{sup 3+} ion transition lines can be obtained. Furthermore, we have investigated the Zeeman g{sub ||}) and g{sub perpendicular}) parameters for the Yb{sup 3+} ion in an Al substitutional site as well as in the V{sub N}-Yb complex using the perturbation theory.

Koubaa, T.; Dammak, M.; Kammoun, M. [Departement de Physique, Groupe de Physique Theorique, Laboratoire de Physique Appliquees, Faculte des Sciences de Sfax, Sfax 3018 (Tunisia); Jadwisienczak, W. M.; Lozykowski, H. J. [School of Electrical Engineering and Computer Science, Ohio University, Ohio 4570 (United States); Anders, A. [Plasma Applications Group, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

2009-07-01

78

Electric-Dipole{endash}Quadrupole Interference of Overlapping Autoionizing Levels in Photoelectron Energy Spectra  

SciTech Connect

We have measured the photon energy dependence of electric-dipole{endash}quadrupole interference in cadmium between the odd parity 4d{sup 9}5s{sup 2}5p J=1 and even parity 5p6p {sup 3} P{sub 2} autoionizing levels. The resonant interference structure is isolated by taking the difference between constant ionic state spectra at 45{degree} with respect to the photon beam in the forward and backward directions. We find interference effects that are approximately 0.5{percent} of the dipole cross section for photon energies of 13thinspeV, in good agreement with theory. We compare the results with those from (e,thinsp2e) experiments. {copyright} {ital 1998} {ital The American Physical Society }

Martin, N.L.; Thompson, D.B.; Bauman, R.P. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)] [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Caldwell, C.D.; Krause, M.O.; Frigo, S.P. [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States)] [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Wilson, M. [Physics Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX (United Kingdom)] [Physics Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX (United Kingdom)

1998-08-01

79

Modeling of the electromagnetic field and level populations in a waveguide amplifier: a multi-scale time problem.  

PubMed

A new algorithm based on auxiliary differential equation and finite difference time domain method (ADE-FDTD method) is presented to model a waveguide whose active layer is constituted of a silica matrix doped with rare-earth and silicon nanograins. The typical lifetime of rare-earth can be as large as some ms, whereas the electromagnetic field in a visible range and near-infrared is characterized by a period of the order of fs. Due to the large difference between these two characteristic times, the conventional ADE-FDTD method is not suited to treat such systems. A new algorithm is presented so that the steady state of rare earth and silicon nanograins electronic levels populations along with the electromagnetic field can be fully described. This algorithm is stable and applicable to a wide range of optical gain materials in which large differences of characteristic lifetimes are present. PMID:24104327

Fafin, Alexandre; Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

2013-10-01

80

Pineal melatonin level disruption in humans due to electromagnetic fields and ICNIRP limits.  

PubMed

The International Agency for Research on Cancer (IARC) classifies electromagnetic fields (EMFs) as 'possibly carcinogenic' to humans that might transform normal cells into cancer cells. Owing to high utilisation of electricity in day-to-day life, exposure to power-frequency (50 or 60 Hz) EMFs is unavoidable. Melatonin is a natural hormone produced by pineal gland activity in the brain that regulates the body's sleep-wake cycle. How man-made EMFs may influence the pineal gland is still unsolved. The pineal gland is likely to sense EMFs as light but, as a consequence, may decrease the melatonin production. In this study, more than one hundred experimental data of human and animal studies of changes in melatonin levels due to power-frequency electric and magnetic fields exposure were analysed. Then, the results of this study were compared with the International Committee of Non-Ionizing Radiation Protection (ICNIRP) limit and also with the existing experimental results in the literature for the biological effect of magnetic fields, in order to quantify the effects. The results show that this comparison does not seem to be consistent despite the fact that it offers an advantage of drawing attention to the importance of the exposure limits to weak EMFs. In addition to those inconsistent results, the following were also observedfrom this work: (i) the ICNIRP recommendations are meant for the well-known acute effects, because effects of the exposure duration cannot be considered and (ii) the significance of not replicating the existing experimental studies is another limitation in the power-frequency EMFs. Regardless of these issues, the above observation agrees with our earlier study in which it was confirmed that it is not a reliable method to characterise biological effects by observing only the ratio of AC magnetic field strength to frequency. This is because exposure duration does not include the ICNIRP limit. Furthermore, the results show the significance of disruption of melatonin due to exposure to weak EMFs, which may possibly lead to long-term health effects in humans. PMID:23051584

Halgamuge, Malka N

2013-05-01

81

Study the effect of gray component replacement level on reflectance spectra and color reproduction accuracy  

NASA Astrophysics Data System (ADS)

The aim of this study is investigation of gray component replacement (GCR) levels on reflectance spectrum for different overprints of the inks and color reproduction accuracy. The most commonly implemented method in practice for generation of achromatic composition is gray component replacement (GCR). The experiments in this study, have been performed in real production conditions with special test form generated by specialized software. The measuring of reflection spectrum of printed colors, gives a complete conception for the effect of different gray component replacement levels on color reproduction accuracy. For better data analyses and modeling of processes, we have calculated (converted) the CIEL*a*b* color coordinates from the reflection spectra data. The assessment of color accuracy by using different GCR amount has been made by calculation of color difference ?E* ab. In addition for the specific printing conditions we have created ICC profiles with different GCR amounts. A comparison of the color gamuts has been performed. For a first time a methodology is implemented for examination and estimation of effect of GCR levels on color reproduction accuracy by studying a big number of colors in entire visible spectrum. Implementation in practice of the results achieved in this experiment, will lead to improved gray balance and better color accuracy. Another important effect of this research is reduction of financial costs of printing production by decreasing of ink consumption, indirect reduction of emissions during the manufacture of inks and facilitates the process of deinking during the recycling paper.

Spiridonov, I.; Shopova, M.; Boeva, R.

2013-03-01

82

Energy Spectra, Composition, and Other Properties of Ground-Level Events During Solar Cycle 23  

NASA Technical Reports Server (NTRS)

We report spacecraft measurements of the energy spectra of solar protons and other solar energetic particle properties during the 16 Ground Level Events (GLEs) of Solar Cycle 23. The measurements were made by eight instruments on the ACE, GOES, SAMPBX, and STEREO spacecraft and extend from approximately 0.1 to approximately 500-700 MeV. All of the proton spectra exhibit spectral breaks at energies ranging from approximately 2 to approximately 46 MeV and all are well fit by a double power-law shape. A comparison of GLE events with a larger sample of other solar energetic particle (SEP) events shows that the typical spectral indices are harder in GLE events, with a mean slope of -3.18 at greater than 40 MeV/nuc. In the energy range 45 to 80 MeV/nucleon about approximately 50% of GLE events have properties in common with impulsive He-3-rich SEP events, including enrichments in Ne/O, Fe/O, Ne-22/Ne-20, and elevated mean charge states of Fe. These He-3 rich events contribute to the seed population accelerated by CME-driven shocks. An analysis is presented of whether highly-ionized Fe ions observed in five events could be due to electron stripping during shock acceleration in the low corona. Making use of stripping calculations by others and a coronal density model, we can account for events with mean Fe charge states of (Q(sub Fe) is approximately equal to +20 if the acceleration starts at approximately 1.24-1.6 solar radii, consistent with recent comparisons of CME trajectories and type-II radio bursts. In addition, we suggest that gradual stripping of remnant ions from earlier large SEP events may also contribute a highly-ionized suprathermal seed population. We also discuss how observed SEP spectral slopes relate to the energetics of particle acceleration in GLE and other large SEP events.

Mewaldt, R. A.; COhen, C. M. S.; Labrador, A. W.; Leske, R. A.; Looper, M. D.; Haggerty, D. K.; Mason, G. M.; Mazur, J. E.; vonRosenvinge, T. T.

2012-01-01

83

Spectra From Space : Main Menu  

NSDL National Science Digital Library

On-line science lesson (grades 7 - 9) - students learn about satellite spectra research, electromagnetic spectrum, do hands-on activities. In this lesson students investigate satellite missions operating in four electromagnetic bands. Students learn about spectra and why satellites gather certain kinds of spectra from space by using the Internet and doing hands-on activities. From the University of California, Berkeley.

1997-01-01

84

The influence of quantum interference effects on the resonance fluorescence spectra of a degenerate three-level atom  

Microsoft Academic Search

The resonance fluorescence spectra of a degenerate three-level atom of the V-type in the field of an intense monochromatic wave with an arbitrary polarization composition are investigated. Analytical\\u000a expressions are derived for the resonance fluorescence spectra, and the angular distribution of spontaneous fluorescence of\\u000a atoms is analyzed for the D-line emitted by vapors of alkali atoms. It is shown that

A. A. Panteleev; Vl. K. Roerieh

2001-01-01

85

Coherent level mixing in dot energy spectra measured by magnetoresonant tunneling spectroscopy of vertical quantum dot molecules  

NASA Astrophysics Data System (ADS)

We study by magnetoresonant tunneling spectroscopy single-particle energy spectra of the constituent weakly coupled dots in vertical quantum dot molecules over a wide energy window. The measured energy spectra are well modeled by calculated spectra for dots with in-plane confinement potentials that are elliptical and parabolic in form. However, in the regions where two, three, or four single-particle energy levels are naively expected to cross, we observe pronounced level anticrossing behavior and strong variations in the resonant currents as a consequence of coherent mixing induced by small deviations in the nearly ideal dot confinement potentials. We present detailed analysis of the energy spectra, and focus on two examples of three-level crossings whereby the coherent mixing leads to concurrent suppression and enhancement of the resonant currents when the anticrossing levels are minimally separated. The suppression of resonant current is of particular interest since it is a signature of dark state formation due to destructive interference. We also describe in detail and compare two measurement strategies to reliably extract the resonant currents required to characterize the level mixing.

Payette, C.; Amaha, S.; Yu, G.; Gupta, J. A.; Austing, D. G.; Nair, S. V.; Partoens, B.; Tarucha, S.

2010-06-01

86

A laboratory investigation of electromagnetic bias in sea level measurements by microwave altimeters  

NASA Technical Reports Server (NTRS)

To contribute to a better understanding of the electromagnetic bias in radar altimetry, a series of experiments was conducted using a focused beam radar set at 13.5-GHz frequency. For pure wind wave fields, the authors found the bias to be a quadratic function of each of the commonly used parameters, namely, the significant wave height, the wind speed, the water elevation skewness, and significant slope. The bias divided by the significant wave height is a linear function of these parameters. The coefficients in bias representation as a function of either the significant wave height or the wind speed are significantly different from values obtained in field experiments. This led to the conclusion that none of the latter parameters can be taken solely to account for all observed bias variations. Instead, dimensionless parameters such as the wave skewness or a dimensionless wave height are shown to be more appropriate.

Branger, H.; Bliven, L.; Ramamonjiarisoa, A.

1991-01-01

87

TEACHING PHYSICS: Demonstrating cosmic ray induced electromagnetic cascades in the A-level laboratory  

NASA Astrophysics Data System (ADS)

This article indicates how the study of sea-level cosmic ray phenomena can have a role in A-level physics. It describes a simple but far reaching particle physics experiment that can be carried out in the A-level physics laboratory. A simple model of electron-positron-photon cascades, suitable for use at A-level, is described.

Dunne, Peter

1999-01-01

88

Time-resolved Fourier transform infrared spectra of Sr: h-, g-levels and oscillator strengths  

NASA Astrophysics Data System (ADS)

We study spectra of a plasma created by the laser ablation of SrF2 targets in a vacuum and report 19 Sr I lines in the range of 1300-5000 cm-1 which have not been observed before. From the recorded spectra we determine the previously unknown excitation energies of 5 g, 6 g and 6 h states of Sr I. We also calculate a large list of transition probabilities and oscillator strengths for Sr I in the observed spectral range. These A- and f-values are calculated using quantum defect theory which shows good agreement with the available experimental and theoretical results.

Civiš, S.; Ferus, M.; Chernov, V. E.; Zanozina, E. M.; Juha, L.

2013-11-01

89

The A~1A'-X~1A' absorption and single vibronic level fluorescence spectra of some deuterated 2-aminopyridines  

NASA Astrophysics Data System (ADS)

The A˜-X˜ systems of three 2-aminopyridines, fully or partially deuterated on the NH 2 group, have been investigated by means of absorption and SVL fluorescence spectra. Absorption bands of a mixture of four species (three deuterated and one undeuterated) can be attributed to a particular species primarily by observing transitions involving the deuterium-sensitive NH 2-inversion vibration in the corresponding SVL fluorescence spectra. The dependence of the wave-number of the vibration ?22 on the degree of deuteration is also helpful in this respect. Evidence for appreciable hydrogen bonding between the ring nitrogen and the hydrogen atom of the NH 2 group is strongly supported by the resulting spectra. The inversion vibration levels for the two partially deuterated species are very different and there is evidence from the spectrum of 2-aminopyridine (-ND 2) that, what would be purely torsional motion of an NH 2 group free from hydrogen bonding, is appreciably modified in 2-aminopyridine.

Hollas, J. Michael; Musa, Hamdan; Ridley, Trevor

1984-03-01

90

Coincident Observation of Lightning using Spaceborne Spectrophotometer and Ground-Level Electromagnetic Sensors  

NASA Technical Reports Server (NTRS)

The present study aims at assessing a possible new way to reveal the properties of lightning flash, using spectrophotometric data obtained by FORMOSAT-2/ISUAL which is the first spaceborne multicolor lightning detector. The ISUAL data was analyzed in conjunction with ground ]based electromagnetic data obtained by Duke magnetic field sensors, NLDN, North Alabama Lightning Mapping Array (LMA), and Kennedy Space Center (KSC) electric field antennas. We first classified the observed events into cloud ]to ]ground (CG) and intra ]cloud (IC) lightning based on the Duke and NLDN measurements and analyzed ISUAL data to clarify their optical characteristics. It was found that the ISUAL optical waveform of CG lightning was strongly correlated with the current moment waveform, suggesting that it is possible to evaluate the electrical properties of lightning from satellite optical measurement to some extent. The ISUAL data also indicated that the color of CG lightning turned to red at the time of return stroke while the color of IC pulses remained unchanged. Furthermore, in one CG event which was simultaneously detected by ISUAL and LMA, the observed optical emissions slowly turned red as the altitude of optical source gradually decreased. All of these results indicate that the color of lightning flash depends on the source altitude and suggest that spaceborne optical measurement could be a new tool to discriminate CG and IC lightning. In the presentation, we will also show results on the comparison between the ISUAL and KSC electric field data to clarify characteristics of each lightning process such as preliminary breakdown, return stroke, and subsequent upward illumination.

Adachi, Toru; Cohen, Morris; Li, Jingbo; Cummer, Steve; Blakeslee, Richard; Marshall, THomas; Stolzenberg, Maribeth; Karunarathne, Sumedhe; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred; Takahashi, Yukihiro; Frey, Harald; Mende, Stephen

2012-01-01

91

Coincident observation of lightning using spaceborne spectrophotometer and ground-level electromagnetic sensors  

NASA Astrophysics Data System (ADS)

The present study aims at assessing a new way to reveal properties of lightning flash, using the spectrophotometric data obtained by FORMOSAT-2/ISUAL which is the first spaceborne multicolor lightning detector. The ISUAL data was analyzed in conjunction with ground-based electromagnetic data obtained by Duke magnetic field sensors, NLDN, North Alabama Lightning Mapping Array (LMA), and University of Mississippi (UM) electric field change antennas operated around Kennedy Space Center. We first classified the observed events into cloud-to-ground (CG) and intra-cloud (IC) lightning based on the Duke and NLDN measurements and analyzed ISUAL data to clarify their optical characteristics. It was found that the ISUAL optical waveform of CG lightning was strongly correlated with the current moment waveform, suggesting that it is possible to evaluate the electrical properties of lightning from satellite optical measurement to some extent. The ISUAL data also indicated that the color of CG lightning turned to red at the time of return stroke while the color of IC pulses remained unchanged. Furthermore, in one CG event which was simultaneously detected by ISUAL and LMA, the observed optical emissions slowly turned red as the altitude of optical source gradually decreased. All of these results indicate that the color of lightning flash depends on the source altitude and suggest that spaceborne optical measurement could be a new tool to discriminate CG and IC lightning. In the presentation, we will also show results on the comparison between the ISUAL and UM electric field change data to clarify characteristics of each lightning process such as preliminary breakdown and return stroke.

Adachi, T.; Cohen, M.; Lu, G.; Cummer, S. A.; Blakeslee, R. J.; Marshall, T.; Stolzenburg, M.; Karunarathne, S.; Hsu, R.; Su, H.; Chen, A. B.; Takahashi, Y.; Mende, S. B.; Frey, H. U.

2012-12-01

92

High Level Parallelization of a 3D Electromagnetic Simulation Code with Irregular Communication Patterns  

Microsoft Academic Search

D simulation in electrical engineering is based on recent researchwork (Whitney's elements, auto-gauged formulations, discretizationof the source terms) and it results in complex and irregular codes.Generally, explicit message passing is used to parallelize this kind ofapplications requiring tedious and error prone low level coding of complexcommunication schedules to deal with irregularity. In this paper,we focus on a high level approach

Emmanuel Cagniot; Thomas Brandes; Jean-luc Dekeyser; Francis Piriou; Pierre Boulet; Stéphance Clénet

2000-01-01

93

Electromagnetically induced left-handedness in a dense gas of three-level atoms  

SciTech Connect

We discuss how a three-level system can be used to change the frequency-dependent magnetic permeability of an atomic gas to be significantly different from 1. We derive the conditions for such a scheme to be successful and briefly discuss the resulting macroscopic electrodynamics. We find that it may be possible to obtain left-handed electrodynamics for an atomic gas using three atomic levels.

Oktel, M.Oe.; Muestecaplioglu, Oe.E. [Department of Physics, Bilkent University, 06800 Bilkent, Ankara (Turkey); Department of Physics, Koc University, Rumelifeneri Yolu, 34450 Sariyer, Istanbul (Turkey)

2004-11-01

94

Children and adults exposed to electromagnetic fields at the ICNIRP reference levels: theoretical assessment of the induced peak temperature increase  

NASA Astrophysics Data System (ADS)

To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body-averaged specific absorption rate (SARwb) are provided to keep the whole-body temperature increase (Tbody, incr) under 1 °C during 30 min. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR10g) are provided to prevent excessive localized tissue heating. The objective of this study is to assess the localized peak temperature increase (Tincr, max) in children upon exposure at the reference levels. Finite-difference time-domain modeling was used to calculate Tincr, max in six children and two adults exposed to orthogonal plane-wave configurations. We performed a sensitivity study and Monte Carlo analysis to assess the uncertainty of the results. Considering the uncertainties in the model parameters, we found that a peak temperature increase as high as 1 °C can occur for worst-case scenarios at the ICNIRP reference levels. Since the guidelines are deduced from temperature increase, we used Tincr, max as being a better metric to prevent excessive localized tissue heating instead of localized peak SAR. However, we note that the exposure time should also be considered in future guidelines. Hence, we advise defining limits on Tincr, max for specified durations of exposure.

Bakker, J. F.; Paulides, M. M.; Neufeld, E.; Christ, A.; Kuster, N.; van Rhoon, G. C.

2011-08-01

95

Effect of Extremely Low Frequency Electromagnetic Field and GABAA Receptors on Serum Testosterone Level of Male Rats  

PubMed Central

Background: GABA can influence the steroidogenesis in peripheral and central nervoussystems. Objectives: The present study investigates the interactive effect of GABAA receptors and extremely low frequency electromagnetic field on serum testosterone level of male rats. Patients and Methods: Fifty adult male rats were randomly assigned into 10 groups. Groups 2, 4, 6, 8, and 10 were exposed to ELF-EMF for 30 days 8hrs per day; while, the remaining groups (1, 3, 5, 7, and 9) were sham exposed animals. At the end of the experiment, animals in groups 1 and 2 received normal saline; while, animals in groups 3 and 4 were treated with 1 mg/kg of bicuculline methiodide, and for animals of groups 5 and 6,3 mg/kg of bicuculline was injected. Animals of groups 7 and 8 were treated with 0.5 mg/kg of muscimol hydrobromide and rats in groups 9 and 10 received 2 mg/kg muscimol hydrobromide. About forty minutes after the injection, blood samples were collected and serum testosterone level was assayed using RIA. Results: Administration of muscimol hydrobromide at both doses to sham exposed rats significantly decreased serum testosterone level as compared to sham exposed animals which received saline. Administration of bicuculline methiodide without exposure to ELF-EMF, had no significant effect on testosterone level as compared to group 1. Serum testosterone levels of rats in different groups, exposed to ELF-EMF were statistically the same. Moreover, serum testosterone of exposed and sham exposed rats in each treatment showed no significant difference. Conclusions: No interactivity is present in modulatory effects of GABAA receptors and ELF-EMFs on serum testosterone of male rats.

Taherianfard, Mahnaz; Bahaddini, Aminolah; Keshtkar, Sara; Fazeli, Mehdi; Shomali, Tahora

2013-01-01

96

Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2  

NASA Astrophysics Data System (ADS)

Absorption and fluorescence spectra of Er3+(4f11) in crystals of NaBi(WO4)2 (NBW) are reported at temperatures between 15 K and room temperature. The absorption spectra include the details of the crystal-field splitting of 11 multiplet manifolds, 2S+1LJ of Er3+(4f11), spanning the wavelength range between 350 nm and 1550 nm. The crystal-field splitting of the ground-state 4I15/2, is obtained from an analysis of the fluorescence spectrum, 4S3/2-->4I15/2. Spectra are characterized by inhomogeneous broadening due to the disordered crystal structure in which different valency cations, Na+ and Bi3+, statistically fill the S4 symmetry sites. The Er3+ ions likely replace the Bi3+ ions in these sites. A quasi-center model has been chosen to interpret the crystal-field splitting of each manifold, using D2d rather than S4 symmetry as the site for the rare-earth ion in the lattice. To test the feasibility of the model, the splitting of the energy levels of Nd3+ in NBW was carried out first and compared with experimental levels reported in literature. A least-squares fitting analysis between 26 calculated-to-observed energy (Stark) levels gave a root-mean-square (rms) deviation of 8 cm-1 for the 4IJ and 4F3/2 multiplet manifolds of Nd3+ in NBW. Using the phenomenological lattice-sum parameters, Anm, obtained from the analysis of the Nd3+ energy levels, we predicted an initial set of crystal-field parameters, Bnm, for Er3+. With only a modest fitting of the multiplet centroids, these Bnm predict the observed splitting in the Er3+ spectra remarkably well. In a fitting of the energy levels in which both the Bnm and centroids are allowed to vary, we obtained a rms deviation of 6 cm-1 for 57 calculated-to-observed Stark levels. The results suggest that the quasi-center model has merit when used to calculate the crystal-field splitting of the energy levels of the trivalent rare-earth ions in crystal hosts having a disordered structure.

Gruber, John B.; Sardar, Dhiraj K.; Russell, Charles C.; Yow, Raylon M.; Zandi, Bahram; Kokanyan, Edvard P.

2003-12-01

97

Ladder structure in the time-domain response of Landau levels to a shock electromagnetic pulse  

NASA Astrophysics Data System (ADS)

Step-like profiels are predicted for the time-domain response of a quasi-two-dimensional system of equidistant levels subjected to resonant excitation by a strongly asymmetric light pulse with a sharp front. Out-of-resonance excitation results in peculiar traces whose forms depend on the detuning from resonance. The structure visibility is a function of the broadening parameters for incident light and electronic excitations. The radiative broadening of Landau electron-hole pairs has been calculated and shown to be proportional to the magnetic field strength.

Lang, I. G.; Belitsky, V. I.

1998-08-01

98

Spectra of relativistic solar proton ground-level events recorded at Sanae, Antarctica  

SciTech Connect

Ten solar proton flare enhancements of more than 5 percent have been recorded at Sanae (70 deg S, 2 deg W) at a cutoff rigidity of 0.86 GV during the last two decades, by both a super neutron monitor and a four-counter neutron-moderated detector. The relative enhancements as recorded by these detectors for different solar flares are summarized and are related to the steepnesses of the relativistic solar flare proton spectra. Variability in the ratio of the relative enhancements observed may be due to a changing energy-dependent release of the protons from the solar flare region or corona, or from changing irregularities in the interplanetary magnetic field. 19 refs.

Stoker, P.H.; Makgamathe, S.

1990-06-01

99

Electromagnetic environmental criteria for US Army missile systems: EMC (electromagnetic compatibility), EMR (electromagnetic radiation), EMI (electromagnetic interference), EMP (electromagnetic pulse), ESD (electrostatic discharge), and lightning  

Microsoft Academic Search

This report presents the design and test requirements in developing an electromagnetic compatibility missile system. Environmental levels are presented for electromagnetic radiation hazards, electromagnetic radiation operational electrostatic discharge, lightning, and electromagnetic pulse (nuclear). Testing techniques and facility capabilities are presented for research and development testing of missile systems.

C. D. Ponds

1985-01-01

100

Effects of simultaneous combined exposure to CDMA and WCDMA electromagnetic fields on serum hormone levels in rats.  

PubMed

Despite more than a decade of research on the endocrine system, there have been no published studies about the effects of concurrent exposure of radiofrequency electromagnetic fields (RF-EMF) on this system. The present study investigated the several parameters of the endocrine system including melatonin, thyroid stimulating hormone, stress hormone and sex hormone after code division multiple access (CDMA, 849 MHz) and wideband code division multiple access (WCDMA, 1.95 GHz) signals for simultaneous exposure in rats. Sprague-Dawley rats were exposed to RF-EMF signals for 45 min/day, 5 days/week for up to 8 weeks. The whole-body average specific absorption rate (SAR) of CDMA or WCDMA was 2.0 W/kg (total 4.0 W/kg). At 4 and 8 weeks after the experiment began, each experimental group's 40 rats (male 20, female 20) were autopsied. Exposure for 8 weeks to simultaneous CDMA and WCDMA RF did not affect serum levels in rats of melatonin, thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxin (T4), adrenocorticotropic hormone (ACTH) and sex hormones (testosterone and estrogen) as assessed by the ELISA method. PMID:23239176

Jin, Yeung Bae; Choi, Hyung-Do; Kim, Byung Chan; Pack, Jeong-Ki; Kim, Nam; Lee, Yun-Sil

2013-05-01

101

Use of pupil size to determine the effect of electromagnetic acupuncture on activation level of the autonomic nervous system.  

PubMed

Magnetic fields are widely considered as a method of treatment to increase the therapeutic effect when applied to acupoints. Hence, this study proposes a new method which creates significant stimulation of acupoints by using weak magnetic fields. We conducted this experiment in order to confirm the effect on the activation level of the autonomic nervous system by measuring pupil sizes in cases of stimulation by using manual acupuncture and electromagnetic acupuncture (EMA) at BL15. We selected 30 Hz of biphasic wave form with 570.1 Gauss. To confirm the biopotential by the magnetic flux density occurring in EMA that affected the activation of the autonomic nervous system, we observed the biopotential induced at the upper and the mid left and right trapezius. We observed a significant decrease in pupil size only in the EMA group (p < 0.05), thus confirming that EMA decreased the pupil size through activation of the parasympathetic nerve in the autonomic nervous system. Moreover, we confirmed that the amplitude of the biopotential which was caused by 570.1 Gauss was higher than ±20 ?A. Thus, we can conclude that EMA treatment successfully activates the parasympathetic nerve in the autonomic nervous system by inducing a biotransformation by the induced biopotential. PMID:24929456

Kim, Soo-Byeong; Choi, Woo-Hyuk; Liu, Wen-Xue; Lee, Na-Ra; Shin, Tae-Min; Lee, Yong-Heum

2014-06-01

102

Charge-transfer satellites in the 2p core-level photoelectron spectra of heavy-transition-metal dihalides  

NASA Astrophysics Data System (ADS)

We extend the charge-transfer model with the core-hole-3d-electron Coulomb attraction [van der Laan et al., Phys. Rev. B 23, 4369 (1981)] to the 2p core-level photoemission satellite structures of cobalt, iron, and manganese dihalides. This model was found to account for the positions and intensities of satellites and main peaks very well with reasonable values of parameters. These parameter values show the expected trends not only along the ligand series from fluorine to bromine but also along the transition-metal series from copper to manganese. This gives us confidence that the charge-transfer mechanism is responsible for the satellite structures in the 2p core-level photoemission spectra of heavy-transition-metal compounds, and that the screening response is important even for insulators in the presence of a core hole. It also suggests the core-level photoemission spectra, if properly understood, can be used to obtain parameters on the valence-electronic structures.

Park, Jaehoon; Ryu, Seungoh; Han, Moon-Sup; Oh, S.-J.

1988-06-01

103

Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals  

NASA Astrophysics Data System (ADS)

Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760 nm (r2 = 0.88, RMSE = 7.54 x 107). When perfect retrievals were assumed (0% noise), retrievals remained good in the low emission regions on either side of the peaks-- those associated with the H alpha line at 655 nm (r2 = 0.83, RMSE =8.87 x 107) and the far-NIR wavelengths recently utilized for satellite retrievals: a K line at 770 nm (r2 = 0.85, RMSE = 8.36 x 107) and the 750-770 nm interval (r2 = 0.88, RMSE = 6.92 x 107). However, the atmosphere and satellite observations are expected to add noise to retrievals. Adding 5% random error to these relationships did not seriously impair the retrieval successes in the red and far-red peaks (r2 ~ 0.85, RMSEs = 6.31 x 107). A greater impact occurred (reducing retrieval success by ~10%) when adding 5% noise for the far-NIR narrow band at 770 nm (r2 ~ 0.70, RMSE ~ 8.5 x 107). When a 10% random error was added, the retrieval successes fell to ~68 ± 7% for all retrieval wavebands, and RMSEs increased by a factor of 10. This laboratory approach will be critical to calibrate space borne retrievals, but additional information across plant species is needed. Furthermore, this experiment indicates that ChlF retrievals from space should include information from the red and far-red peak emission regions, since the true total fluorescence signal is the desired parameter for Earth carbon and energy budgets.

Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

2012-12-01

104

Effect of light polarization and dimensions of ?-type three level cylindrical quantum dot on electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

In this paper, electromagnetically induced transparency (EIT) is investigated in a GaAs cylindrical quantum dot (QD) with parabolic potential. The Schrödinger equation is solved in effective mass, eigenfunctions and eigenvalues of QD. Using obtained eigenfunctions and eigenvalues, susceptibility of cylindrical QD is found. Dependence of electromagnetically induced transparency on radius and height of cylindrical QD, polarization of probe and control lasers, Rabi and probe frequencies, decay rate and detuning of the control laser are also investigated.

Raki, Z.; Askari, H. R.

2014-01-01

105

Extremely low-frequency electromagnetic fields affect transcript levels of neuronal differentiation-related genes in embryonic neural stem cells.  

PubMed

Previous studies have reported that extremely low-frequency electromagnetic fields (ELF-EMF) can affect the processes of brain development, but the underlying mechanism is largely unknown. The proliferation and differentiation of embryonic neural stem cells (eNSCs) is essential for brain development during the gestation period. To date, there is no report about the effects of ELF-EMF on eNSCs. In this paper, we studied the effects of ELF-EMF on the proliferation and differentiation of eNSCs. Primary cultured eNSCs were treated with 50 Hz ELF-EMF; various magnetic intensities and exposure times were applied. Our data showed that there was no significant change in cell proliferation, which was evaluated by cell viability (CCK-8 assay), DNA synthesis (Edu incorporation), average diameter of neurospheres, cell cycle distribution (flow cytometry) and transcript levels of cell cycle related genes (P53, P21 and GADD45 detected by real-time PCR). When eNSCs were induced to differentiation, real-time PCR results showed a down-regulation of Sox2 and up-regulation of Math1, Math3, Ngn1 and Tuj1 mRNA levels after 50 Hz ELF-EMF exposure (2 mT for 3 days), but the percentages of neurons (Tuj1 positive cells) and astrocytes (GFAP positive cells) were not altered when detected by immunofluorescence assay. Although cell proliferation and the percentages of neurons and astrocytes differentiated from eNSCs were not affected by 50 Hz ELF-EMF, the expression of genes regulating neuronal differentiation was altered. In conclusion, our results support that 50 Hz ELF-EMF induce molecular changes during eNSCs differentiation, which might be compensated by post-transcriptional mechanisms to support cellular homeostasis. PMID:24595264

Ma, Qinlong; Deng, Ping; Zhu, Gang; Liu, Chuan; Zhang, Lei; Zhou, Zhou; Luo, Xue; Li, Min; Zhong, Min; Yu, Zhengping; Chen, Chunhai; Zhang, Yanwen

2014-01-01

106

Low-level laser therapy vs. pulsed electromagnetic field on neonatal rat calvarial osteoblast-like cells.  

PubMed

To compare the effects of pulsed electromagnetic field (PEMF) and low-level laser therapy (LLLT) on osteoblast cells in a cell culture model. Fifty thousand neonatal rat calvarial osteoblast-like cells per milliliter were seeded and 0.06 mT PEMF, 0.2 mT PEMF, and LLLT at 808 nm were applied for 24 and 96 h on the cells. To evaluate cellular proliferation and differentiation, specimens were examined for DNA synthesis, alkaline phosphatase (ALP) activity, cell numbers, and viability of the cells. Morphological appearances of the cells were observed using scanning electron microcopy after 24 and 96 h of incubation. At 24 and 96 h, the control group had a higher cell proliferation than 0.06 and 0.2 mT PEMF groups (p=0.001). At 96 h, 0.2 mT PEMF group had higher cell proliferation rate than 0.06 mT PEMF and LLLT groups (p=0.001). The cell count and cell viability in 0.2 mT PEMF group were higher than the 0.06-mT PEMF and LLLT groups, although these differences were not statistically significant at 96 h (p>0.05). At 24 and 96 h, cell viability in the control group was higher than the test groups. Alkaline phosphatase levels of the groups were comparable in both time intervals (p>0.05). 0.2 mT PEMF application on osteoblast-like cells led to cell proliferation and differentiation better than 0.06 mT PEMF and LLLT at 808 nm, although a remarkable effect of both PEMF and LLLT could not be detected. The ALP activity of 0.2 and 0.06 mT PEMF and LLLT were comparable. PMID:22865122

Emes, Yusuf; Akça, Kivanç; Aybar, Buket; Yalç?n, Serhat; Çavu?o?lu, Yeliz; Baysal, U?ur; I?sever, Halim; Atalay, Belir; Vural, Pervin; Ergüven, Mine; Çehreli, Murat Cavit; Bilir, Ayhan

2013-05-01

107

Project Spectra!  

NSDL National Science Digital Library

This is an electromagnetic spectrum science program that incorporates engineering, math, and solar system data stories that use mission data to explain how light is used to explore the solar system. A set of foundational lessons accompanies the program, helping students understand spectroscopy at a basic level. The data stories include paper and pencil versions, as well as Flash-based interactives where students delve more deeply into the missions and science behind the data.

2009-12-01

108

Analysis of High Cadence In Situ Solar Wind Ionic Composition Data Using Wavelet Power Spectra Confidence Levels  

NASA Astrophysics Data System (ADS)

The variability inherent in solar wind composition has implications for the variability of the physical conditions in its coronal source regions, providing constraints on models of coronal heating and solar wind generation. We present a generalized prescription for constructing a wavelet power significance measure (confidence level) for the purpose of characterizing the effects of missing data in high cadence solar wind ionic composition measurements. We describe the data gaps present in the 12 minute Advanced Composition Explorer/Solar Wind Ionic Composition Spectrometer observations of O7 +/O6 + during 2008. The decomposition of the in situ observations into "good measurement" and "no-measurement" signals allows us to evaluate the performance of a filler signal, i.e., various prescriptions for filling the data gaps. We construct Monte Carlo simulations of synthetic O7 +/O6 + composition data and impose the actual data gaps that exist in the observations in order to investigate two different filler signals: one, a linear interpolation between neighboring good data points, and two, the constant mean value of the measured data. Applied to these synthetic data plus filler signal combinations, we quantify the ability of the power spectra significance level procedure to reproduce the ensemble-averaged time-integrated wavelet power per scale of an ideal case, i.e., the synthetic data without imposed data gaps. Finally, we present the wavelet power spectra for the O7 +/O6 + data using the confidence levels derived from both the mean value and linear interpolation data gap filling signals and discuss the results.

Edmondson, J. K.; Lynch, B. J.; Lepri, S. T.; Zurbuchen, T. H.

2013-12-01

109

Predicting foliar biochemistry of tea (Camellia sinensis) using reflectance spectra measured at powder, leaf and canopy levels  

NASA Astrophysics Data System (ADS)

Some biochemical compounds are closely related with the quality of tea (Camellia sinensis (L.)). In this study, the concentration of these compounds including total tea polyphenols, free amino acids and soluble sugars were estimated using reflectance spectroscopy at three different levels: powder, leaf and canopy, with partial least squares regression. The focus of this study is to systematically compare the accuracy of tea quality estimations based on spectroscopy at three different levels. At the powder level, the average r2 between predictions and observations was 0.89 for polyphenols, 0.81 for amino acids and 0.78 for sugars, with relative root mean square errors (RMSE/mean) of 5.47%, 5.50% and 2.75%, respectively; at the leaf level, the average r2 decreased to 0.46-0.81 and the relative RMSE increased to 4.46-7.09%. Compared to the results yielded at the leaf level, the results from canopy spectra were slightly more accurate, yielding average r2 values of 0.83, 0.77 and 0.56 and relative RMSE of 6.79%, 5.73% and 4.03% for polyphenols, amino acids and sugars, respectively. We further identified wavelength channels that influenced the prediction model. For powder and leaves, some bands identified can be linked to the absorption features of chemicals of interest (1648 nm for phenolic, 1510 nm for amino acids, 2080 nm and 2270 nm for sugars), while more indirectly related wavelengths were found to be important at the canopy level for predictions of chemical compounds. Overall, the prediction accuracies achieved at canopy level in this study are encouraging for future study on tea quality estimated at the landscape scale using airborne and space-borne sensors.

Bian, Meng; Skidmore, Andrew K.; Schlerf, Martin; Wang, Tiejun; Liu, Yanfang; Zeng, Rong; Fei, Teng

2013-04-01

110

Temperature coefficients of monolithic III-V triple-junction solar cells under different spectra and irradiance levels  

NASA Astrophysics Data System (ADS)

A complete set of temperature coefficients determined under controlled laboratory conditions is reported for a lattice-matched Ga0.50In0.50P/Ga0.99In0.01As/Ge and metamorphic (MM) Ga0.35In0.65P/Ga0.83In0.17As/Ge triple-junction solar cell. The cells have been investigated at one sun condition at different temperatures and spectra in order to identify a possible influence of the spectrum on the temperature coefficients. At the same time, the cells have been investigated at different temperatures and concentration levels to study the behaviour of the temperature coefficients under concentration.

Fernández, E. F.; Siefer, G.; Schachtner, M.; García Loureiro, A. J.; Pérez-Higueras, P.

2012-10-01

111

Noise levels, spectra, and operational function of an occupied newborn intensive care unit built to meet recommended permissible noise criteria  

NASA Astrophysics Data System (ADS)

A group of clinical experts developed recommended permissible noise criteria for newly constructed or renovated hospital nurseries [Philbin et al., J. Perinatol. 19, 559-563 (2000); R. White, ibid. 23, S1-22 (2003)]. These criteria are based principally on research regarding wake-up thresholds for term newborns and speech interference levels for adults. These criteria are: The overall continuous A-weighted, slow response, sound level at any bed or patient care area shall not exceed: (1) an hourly Leq of 50 dB, (2) an hourly L10 of 55 dB, and (3) a 1-s Lmax of 70 dB. A new hospital building was designed to meet these criteria by using specific acoustical criteria for the structure and space arrangement [J. B. Evans and M. K. Philbin, J. Perinatol. 20, S105-S112 (2000)]. Acoustical criteria for sound isolation, background NC, structural vibration, and reverberation will be presented along with space arrangements that ensure staff efficiency, clinical safety, and family privacy. Post-occupancy measurements of sound levels and spectra along with photographs of a nursery in operation will be presented to illustrate how an ICU can have a quiet, highly functioning intensive care environment while meeting the operational goals and acoustical criteria.

Philbin, M. Kathleen; Evans, Jack B.

2003-10-01

112

Electromagnetically Tunable Fluids.  

National Technical Information Service (NTIS)

The overarching goal of this project was to exploit the transport properties at colloidal and microfluidic dimensions to controllably alter the high-frequency electromagnetic material properties at the macro level. This was to achieve multifunctionality a...

D. Lagoudas G. H. Huff J. Boyd M. A. Bevan Z. Ounaies

2011-01-01

113

304 A? photoelectron spectra of atomic Hg, Tl, and Pb 5d levels; interaction of open shells  

NASA Astrophysics Data System (ADS)

Photoelectron spectra of atomic Hg, Tl, and Pb 5d levels are reported using He ii 304 A? radiation. The spectrum of Hg is simple and shows only a spin-orbit doublet. The spectra of Tl and Pb are complex, both consisting of eight lines. Using the energies from the optical data and the existing intermediate-coupling-configuration-intercation calculations, the Tl spectrum could be assigned. The calculated intensity distribution correlates with the observed one in Tl very closely. In the Pb spectrum only the two strongest lines could be identified and tentatively assigned to the 5d9(2D5/2)6s26p21/2 and 5d9(2D3/2)6s26p21/2 states of Pb+. Both in Tl and Pb, ionization from the 5d5/2 and 5d3/2 subshells can be understood in terms of a special kind of two-electron configuration-interaction mechanism. The 5d9(2D3/2) 6s26pn1/2 (n=1 for Tl and 2 for Pb) hole resulting from the ionization of an 5d3/2 electron, interacts strongly with the 5d9(2D5/2)6s26pn-11/26p13/2 states in which one electron from the (closed) 5d5/2 subshell drops to the 5d3/2 hole and another electron from the 6p1/2 subshell moves up to 6p3/2 subshell. This one-electron-down one-electron-up mechanism (a virtual Auger process) is favored for the 5d3/2 and not for the 5d5/2 subshell for energetic reasons and is responsible for the occurrence of multiline structure for one and not the other.

Süzer, Sefik

1980-06-01

114

Electromagnetic fields affect transcript levels of apoptosis-related genes in embryonic stem cell-derived neural progenitor cells  

Microsoft Academic Search

Mouse embryonic stem (ES) cells were used as an experimental model to study the effects of electromagnetic fields (EMF). ES-derived nestin-positive neural progenitor cells were exposed to extremely low frequency EMF simulating power line magnetic fields at 50 Hz (ELF-EMF) and to radiofrequency EMF simulating the Global System for Mobile Communication (GSM) signals at 1.71 GHz (RF-EMF). Following EMF exposure,

Teodora Nikolova; Jaroslaw Czyz; Alexandra Rolletschek; Przemyslaw Blyszczuk; Jörg Fuchs; Gabriele Jovtchev; Jürgen Schuderer; Niels Kuster; Anna M. Wobus

2005-01-01

115

Images and Spectra of Artificial Aurora and TMA Releases: Low-Light Level Airglow Observations During the TOMEX Rocket Experiment*  

NASA Astrophysics Data System (ADS)

We present the first dedicated measurements of Artificial Aurora (AA), a phenomena often observed during rocket-borne TMA releases [cf., Gelinas, et al., 2001]. Previously, only a few images of the Artificial Aurora have been documented and these were obtained using instruments designed and dedicated to tracking TMA trails and their motion. Our observations were made in conjunction with a nighttime E-region study known as the Turbulent Oxygen Mixing EXperiment (TOMEX) that was flown from White Sands Missile Range on Oct. 26, 2000. NRL provided three cameras and a spectrograph solely for observing the AA. The instruments were located at a site almost directly under apogee and all operated successfully during the mission. We will primarily present results from two of these instruments. First, a LLLTV (Low-Light Level Television) camera captured extremely detailed video-rate images of the Artificial Aurora. These video images show significantly more of the structure, dynamics and phenomenology of the Artificial Aurora than previous 'still' images. The aurora appears near 115 km altitude, projected down along the magnetic field line that the rocket is crossing. The LLLTV images show that the aurora becomes visible as the rocket passes through 135 km altitude on the upleg of the trajectory. Second, a compact-grating spectrograph was mated with another LLLTV to attempt to measure the optical spectrum of the AA emissions. The spectrograph was capable of monitoring airglow from about 330nm (limited by atmospheric Blue/NUV scattering and absorption) up to 760 nm. Clear spectra were obtained for the TMA trails, the 're-entry bag' (a bright TMA related emission that occurs as the rocket nears 100 km) and a portion of the AA after the re-entry bag and the AA merged-and-brightened. Preliminary processing of spectra when pointed only at the Artificial Aurora show an increase in the detected emission, but with a low S/N level. Further processing is necessary to extract useful information from the data. From these two sets of optical data, we have greatly increased our understanding of the phenomenology of the Artificial Aurora. We will discuss both of the new data sets and outline how new and developing theories for the generation of the AA are affected by the results. Gelinas, L. J., M. C. Kelley, C. Sia, and M. F. Larsen, Auroral emission generated by a TMA release, JGR, in press 2001. *The work at NRL was supported by the Office of Naval Research

Siefring, C. L.; Gelinas, L. J.; Bernhardt, P. A.; Larsen, M. F.; Makela, J. J.; Kelley, M. C.; Hecht, J. H.

2001-05-01

116

OptaDOS: A tool for obtaining density of states, core-level and optical spectra from electronic structure codes  

NASA Astrophysics Data System (ADS)

We present OptaDOS, a program for calculating core-electron and low-loss electron energy loss spectra (EELS) and optical spectra along with total-, projected- and joint-density of electronic states (DOS) from single-particle eigenenergies and dipole transition coefficients. Energy-loss spectroscopy is an important tool for probing bonding within a material. Interpreting these spectra can be aided by first principles calculations. The spectra are generated from the eigenenergies through integration over the Brillouin zone. An important feature of this code is that this integration is performed using a choice of adaptive or linear extrapolation broadening methods which we show produces higher accuracy spectra than standard fixed-width Gaussian broadening. OptaDOS  may be straightforwardly interfaced to any electronic structure code. OptaDOS  is freely available under the GNU General Public licence from http://www.optados.org.

Morris, Andrew J.; Nicholls, Rebecca J.; Pickard, Chris J.; Yates, Jonathan R.

2014-05-01

117

The Complex Core Level Spectra of CeO2: An Analysis in Terms of Atomic and Charge Transfer Effects  

SciTech Connect

We present a rigorous parameter-free theoretical treatment of the Ce 4s and 5s photoelectron spectra of CeO2. In the currently accepted model the satellite structure in the photoelectron spectra is explained in terms of a mixed valence (Ce 4f0 O 2p6, Ce 4f1 O 2p5, and Ce 4f2 O 2p4) con?guration. We show that charge transfer (CT) into Ce 5d as well as con?gurations involving intra-atomic movement of charge must be considered in addition and compute their contributions to the spectra.

Bagus, Paul S.; Nelin, Constance J.; Ilton, Eugene S.; Baron, Martin; Abbott, Heather; Primorac, Elena; Kuhlenbeck, Helmut; Shaikhutdinov, Shamil; Freund, Hans-Joachim

2010-03-05

118

Mapping subsurface pathways for contaminant migration at a proposed low level waste disposal site using electromagnetic methods  

SciTech Connect

Electromagnetic methods have been used to measure apparent terrain conductivity in the downstream portion of a watershed in which a waste disposal site is proposed. At that site, the pathways for waste migration in ground water are controlled by subsurface channels. The channels are identified using isocurves of measured apparent conductivity. Two upstream channel branches are found to merge into a single downstream channel which constitutes the main drainage path out of the watershed. The identification and mapping of the ground water pathways is an important contribution to the site characterization study and the pathways analysis. The direct applications of terrain conductivity mapping to the planning of the monitoring program, the hydrogeological testing, and the modeling study are demonstrated. 7 references, 4 figures.

Pin, F.G.; Ketelle, R.H.

1984-01-01

119

Electromagnetic Suspension.  

National Technical Information Service (NTIS)

The electromagnetic suspension suggested differs from known suspensions in that its rotor is made in the form of a rod placed between the poles of the electromagnets of an n-phase system. This invention can be used in gravimetry and gyroscopic devices. (A...

B. V. Bolotov L. Z. Piven

1973-01-01

120

Electromagnetic Attraction.  

ERIC Educational Resources Information Center

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)

Milson, James L.

1990-01-01

121

Virtual Electromagnet  

NSDL National Science Digital Library

This is an interactive online activity, in which learners equip a virtual electromagnet and see how many iron filings it can pick up. Learners change various characteristics of the electromagnet including the number of windings, the gage of the wire, the current type (AC or DC), the material used in the wire, and the voltage on the power supply.

Regents, The U.

2014-01-01

122

Electromagnetic environmental criteria for US Army missile systems: EMC (electromagnetic compatibility), EMR (electromagnetic radiation), EMI (electromagnetic interference), EMP (electromagnetic pulse), ESD (electrostatic discharge), and lightning. Final report for period ending October 1986  

Microsoft Academic Search

This report presents the design and test requirements in developing an electromagnetic compatibility missile system. Environmental levels are presented for electromagnetic radiation hazards, electromagnetic radiation operational electrostatic discharge, lightning, and electromagnetic pulse (nuclear). Testing techniques and facility capabilities are presented for research and development testing of missile systems.

M. Kilpatrick; C. D. Ponds

1987-01-01

123

Ab Initio Determinations of Photoelectron Spectra Including Vibronic Features: An Upper-Level Undergraduate Physical Chemistry Laboratory  

ERIC Educational Resources Information Center

We present a first-principles determination of the photoelectron spectra of water and hypochlorous acid as a laboratory exercise accessible to students in an undergraduate physical chemistry course. This paper demonstrates the robustness and user-friendliness of software developed for the Franck-Condon factor calculation. While the calculator is…

Lord, Richard L.; Davis, Lisa; Millam, Evan L.; Brown, Eric; Offerman, Chad; Wray, Paul; Green, Susan M. E.

2008-01-01

124

Electromagnetic fasteners  

DOEpatents

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.

Crane, Randolph W. (Idaho Falls, ID); Marts, Donna J. (Idaho Falls, ID)

1994-01-01

125

The Electromagnetic Spectrum: Projecting Visible Spectra  

NSDL National Science Digital Library

In this activity, students study the range of colors in a visible light spectrum created from either a glass prism or holographic diffraction grating. This activity is in unit 2 of the "Space-Based Astronomy" guide that contains background information, worksheets, assessment activities, extensions, and alignment to national education standards.

126

XWVG: A waveguide program for trilinear tropospheric ducts. Computer program for calculating the signal levels of EM (Electromagnetic) waves propagating over seawater  

NASA Astrophysics Data System (ADS)

XWVG is a reliable waveguide program for calculating the coherent and incoherent mode sum values of the electromagnetic field strength in dB relative to the free space value, for signals propagating in a trilinear tropospheric duct over seawater. XWVG allows for the effects of surface roughness, absorption by atmospheric gases, and the variation of the complex index of refraction of seawater as a function of temperature, salinity, and frequency. XWVG has been successfully used in the frequency range 50 MHz to 94 GHz and should be usable at higher frequencies. XWVG uses the root-finding routine of Shellman and Morfitt to find the complex modes propagating in the duct. This guarantees that all modes with an attenuation rate below a prespecified level will be found. A description of XWVG is provided, along with a complete program listing and sample output.

Baumgartner, G. B., Jr.

1983-06-01

127

Free Ion 4fn Levels of the Tetravalent Lanthanides. Fluorescence and Absorption Spectra of Cesium Dysprosium (IV) Heptafluoride  

Microsoft Academic Search

When a mixture of chloride or sulfate salts of cesium and dysprosium in a 3:1 mole ratio was treated with fluorine gas at 10-60 psig and 200°-350°C, the white Dy(III) starting material was converted to an orange compound with an empirical formula approaching Cs3DyF7. Fluorescence and infrared absorption spectra of fluorocarbon mulls of the orange fluorination product, measured at liquid

Louis P. Varga; Larned B. Asprey

1968-01-01

128

Satellite structures in Mn 2 p X-ray photoemission core-level spectra of Mn/Au(001) and Mn/Pt(001) thin-film systems  

NASA Astrophysics Data System (ADS)

Mn core-level spectra of Mn/Au(001) and Mn/Pt(001) systems are investigated by using X-ray photoemission spectroscopy. For the Mn/Au(001) system, large satellite structures which are very similar to those found previously in Mn/Cu(001) and Mn/Ag(001) systems, are also observed in the Mn 2 p core level spectra. On the other hand, such large satellite structures are not observed in the case of the Mn/Pt(001) system. Considering the results of the structural analysis, these results indicate that the large satellite effect observed in Mn thin film systems is mainly related to the hybridization of Mn d electrons with the substrate, not to the effect of low-dimensionality as claimed in previous reports.

Kim, Wondong; Hwang, Chanyong; Kim, Ilyou

2012-04-01

129

Electromagnetic Hypersensitivity  

Microsoft Academic Search

\\u000a Electromagnetic hypersensitive persons (EHS) attribute their nonspecific health symptoms to environmental electromagnetic\\u000a fields (EMF) of different sources in or outside their homes. In general, causal attribution is not restricted to specific\\u000a EMF frequencies but involves a wide range from extremely low frequencies (ELF) up to radio frequencies (RF) including mobile\\u000a telecommunication microwaves and radar. EHS argue that existing exposure limits

Norbert Leitgeb

130

Electromagnetic Math  

NSDL National Science Digital Library

This book offers an introduction to the electromagnetic spectrum using examples of data from a variety of NASA missions and satellite technologies. The 84 problem sets included allow students to explore the concepts of waves, wavelength, frequency, and speed; the Doppler Shift; light; and the energy carried by photons in various bands of the spectrum. Extensive background information is provided which describes the nature of electromagnetic radiation.

131

The effect of low level radiofrequency electromagnetic radiation on the excretion rates of stress hormones in operators during 24-hour shifts.  

PubMed

The aim of the study was to investigate the effect of long term exposure to low level radiofrequency (RF) electromagnetic (EM) radiation on the excretion rates of stress hormones in satellite station operators during 24-hour shifts. Twelve male operators at a satellite station for TV communications and space research were studied during 24-hour shifts. Dosimetric evaluation of the exposure was carried out and showed low level exposure with specific absorption of 0.1127 J.kg-1. A control group of 12 unexposed male operators with similar job task and the same shift system were studied, too. The 11-oxycorticosteroids (11-OCS), adrenaline and noradrenaline were followed by spectrofluorimetric methods on 3-hour intervals during the 24-hour shifts. The data were analyzed by tests for interindividual analysis, Cosinor analysis and analysis of variance (ANOVA). Significant increase in the 24-hour excretion of 11-OCS and disorders in its circadian rhythm, manifested by increase in the mesor, decrease in the amplitude and shift in the acrophase were found in the exposed operators. The changes in the excretion rates of the catecholamines were significant and showed greater variability of both variables. The long term effect of the exposure to low-level RF EM radiation evoked pronounced stress reaction with changes in the circadian rhythm of 11-OCS and increased variability of catecholamines secretion. The possible health hazards associated with observed alteration in the stress system need to be clarified by identification of their significance and prognostic relevance. PMID:12096679

Vangelova, K; Israel, M; Mihaylov, S

2002-06-01

132

Simultaneous electromagnetically induced transparency for two circularly polarized lasers coupled to the same linearly polarized laser in a four-level atomic system in the W scheme  

SciTech Connect

Electromagnetic induced transparency (EIT) can be produced in a four-level atomic system in the W scheme using a linearly polarized optical field for simultaneously slowing down two {sigma}{sup +} and {sigma}{sup -} circularly polarized optical fields. This four-level atomic system can be set up with a |{sup 1}S{sub 0}> ground state and three Zeeman levels of the |{sup 1}P{sub 1}> excited state of any alkali-metal atom placed in a weak magnetic field. We apply our W scheme to ultracold magnesium atoms for neglecting the collisional dephasing. Atomic coherences are reported after solving a density matrix master equation including radiative relaxations from Zeeman states of the |{sup 1}P{sub 1}> multiplet to the |{sup 1}S{sub 0}> ground state. The EIT feature is analyzed using the transit time between the normal dispersive region and the EIT region. The evolution of the EIT feature with the variation of the coupling field is discussed using an intuitive dressed-state representation. We analyze the sensitivity of an EIT feature to pressure broadening of the excited Zeeman states.

Bahrim, Cristian; Nelson, Chris [Department of Physics, Lamar University, P.O. Box 10046, Beaumont, Texas 77710 (United States)

2011-03-15

133

The A~1A'-X~1A' absorption and single vibronic level fluorescence spectra of 2-aminopyridine  

NASA Astrophysics Data System (ADS)

It has been shown previously [ J. M. Hollas, G. H. Kirby, and R. A. Wright, Mol. Phys.18, 327-335 (1970) ] that there is a close similarity between the rotational contours, and almost certainly the geometry changes, in the A˜-X˜ systems of 2-aminopyridine and aniline. Here it is shown, by a combination of absorption and SVL fluorescence spectra, that the similarity extends to the activity of ?1, the NH 2-inversion vibration, in the à and X˜ states. The I11, I02, and I20 bands are intense and their assignments have been confirmed. It seems certain that there is a large decrease in the out-of-plane angle of the hydrogen atoms of the NH 2 group from the X˜ to the à state perhaps, like aniline, resulting in planarity in the à state. A very large Duschinsky effect involving the a? vibrations ?29 and ?31 enables the identification of these two fundamentals, in the X˜ state, in the gas-phase far-infrared spectrum [ R. A. Kydd, Spectrochim. Acta A35, 409-413 (1979) ]. Other information from SVL fluorescence spectra also leads to the identification of ?? 22, ?? 23 and ?? 30 from the far-infrared spectrum. The intensity distribution along the 22 n1 progression shows a minimum at 22 11. Franck-Condon factor calculations of this intensity pattern show that the change in Q22( Q6 a) from the X˜ to the à state is 0.343u 1/2 Å. A comparison between photographic and photoelectric recording of the 0 00 and I11 SVL fluorescence spectra shows that photographic recording is slower by a factor of at least 5. The only virtue of photographic recording is the ease of calibration.

Hollas, J. Michael; Musa, Hamdan; Ridley, Trevor

1984-03-01

134

Plasmon losses in core-level photoemission spectra studied by the quantum Landau formula including full multiple scattering  

NASA Astrophysics Data System (ADS)

We study the angular and energy dependence of surface and bulk plasmon losses accompanying deep core excitations in simple metals. Here full multiple scatterings of photoelectrons are taken into account before and after the plasmon losses within the quantum Landau formula, which can describe overall features of the photoemission bands. For example, multiple plasmon loss features can be calculated by use of the formula. Two simple metals, Al and Na, are studied here. The depth profiles of the plasmon losses are strongly influenced by the elastic scatterings. The model assuming single elastic scatterings overestimates the losses from deep emitters due to the forward focusing effects, whereas the model accounting for full multiple scatterings gives a much rapidly decaying function of the depth due to the defocusing effects and rich structures due to the photoelectron diffraction. The single elastic scattering approximation gives a poor result both for the depth profiles and for the loss spectra. The present multiple scattering calculations successfully explain the azimuthal dependence of the loss spectra, which reflect the local geometry around the emitters.

Kazama, Misato; Shinotsuka, Hiroshi; Ohori, Yusuke; Niki, Kaori; Fujikawa, Takashi; Kövér, László

2014-01-01

135

Level 0 to 1 processing of the imaging Fourier transform spectrometer GLORIA: generation of radiometrically and spectrally calibrated spectra  

NASA Astrophysics Data System (ADS)

The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an imaging Fourier transform spectrometer that is capable of operating on various high altitude research aircraft. It measures the atmospheric emission in the thermal infrared spectral region in limb and nadir geometry. GLORIA consists of a classical Michelson interferometer combined with an infrared camera. The infrared detector has a usable range of 128 × 128 pixels, measuring up to 16 384 interferograms simultaneously. Imaging Fourier transform spectrometers impose a number of challenges with respect to instrument calibration and algorithm development. The innovative optical setup with extremely high optical throughput requires the development of new methods and algorithms for spectral and radiometric calibration. Due to the vast amount of data there is a high demand for scientifically intelligent optimisation of the data processing. This paper outlines the characterisation and processing steps required for the generation of radiometrically and spectrally calibrated spectra. Methods for performance optimisation of the processing algorithm are presented. The performance of the data processing and the quality of the calibrated spectra are demonstrated for measurements collected during the first deployments of GLORIA on aircraft.

Kleinert, A.; Friedl-Vallon, F.; Guggenmoser, T.; Höpfner, M.; Neubert, T.; Ribalda, R.; Sha, M. K.; Ungermann, J.; Blank, J.; Ebersoldt, A.; Kretschmer, E.; Latzko, T.; Oelhaf, H.; Olschewski, F.; Preusse, P.

2014-03-01

136

The electronic spectrum of the fluoroborane free radical. II. Analysis of laser-induced fluorescence and single vibronic level emission spectra  

NASA Astrophysics Data System (ADS)

Subsequent to our spectroscopic detection of the HBX (X=F, Cl, Br) free radicals (S.-G. He, F. X. Sunahori, and D. J. Clouthier, J. Am. Chem. Soc. 127, 10814 (2005)), the electronic spectrum of the A~ 2A''?-X~ 2A' system of the fluoroborane (HBF) radical in the 600-745 nm region has been studied in detail using the pulsed discharge jet technique. The band system involves a linear-bent transition between the two Renner-Teller components of what would be a 2? state at linearity. Using the results of our theoretical study of the ground and excited state vibrational energy levels and 11B-10B isotope shifts (see the companion paper), the vibrational quantum numbers of the bands in the laser-induced fluorescence (LIF) spectra have been assigned. Rotational and vibrational analyses of the LIF and wavelength resolved emission spectra have been carried out, from which the linear excited state and the bent ground state equilibrium configurations have been confirmed. The ground state molecular geometry of HBF has been determined as r0(BH)=1.214(2) A?, r0(BF)=1.303 4(5) A?, and ?=120.7(1)°. Based on high-level ab initio calculations and symmetry considerations, predissociation of the excited state into H(2S)+BF(1?+) on the ground state potential energy surface is identified as the cause of the breaking off of fluorescence in the LIF spectra.

Sunahori, Fumie X.; Clouthier, Dennis J.

2009-04-01

137

Electromagnetic strong plasma turbulence  

NASA Astrophysics Data System (ADS)

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.

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

2007-02-01

138

Electromagnet Lesson  

NSDL National Science Digital Library

This hands-on classroom activity will help students understand the connections between magnets and electricity generation. The learning cycle planner includes an exploration phase with a hands-on activity and a suggested video. The concept development phase suggests showing the film "Who Killed the Electric Car?" The main part of this learning unit is the electromagnet lesson, which is a two day small group activity in which students will create an electromagnet. This document may be downloaded in PDF file format; student worksheets are included.

Orzali, Joe

2011-12-08

139

The role of Rydberg and continuum levels in computing high harmonic generation spectra of the hydrogen atom using time-dependent configuration interaction  

SciTech Connect

We study the role of Rydberg bound-states and continuum levels in the field-induced electronic dynamics associated with the High-Harmonic Generation (HHG) spectroscopy of the hydrogen atom. Time-dependent configuration-interaction (TD-CI) is used with very large atomic orbital (AO) expansions (up to L= 4 with sextuple augmentation and off-center functions) to describe the bound Rydberg levels, and some continuum levels. To address the lack of ionization losses in TD-CI with finite AO basis sets, we employed a heuristic lifetime for energy levels above the ionization potential. The heuristic lifetime model is compared against the conventional atomic orbital treatment (infinite lifetimes), and a third approximation which is TD-CI using only the bound levels (continuum lifetimes go to zero). The results suggest that spectra calculated using conventional TD-CI do not converge with increasing AO basis set size, while the zero lifetime and heuristic lifetime models converge to qualitatively similar spectra, with implications for how best to apply bound state electronic structure methods to simulate HHG. The origin of HHG spectral features including the cutoff and extent of interference between peaks is uncovered by separating field-induced coupling between different types of levels (ground state, bound Rydberg levels, and continuum) in the simulated electronic dynamics. Thus the origin of deviations between the predictions of the semi-classical three step model and the full simulation can be associated with particular physical contributions, which helps to explain both the successes and the limitations of the three step model.

Luppi, Eleonora [Laboratoire de Chimie Théorique, Université Pierre et Marie Curie, 75005 Paris (France)] [Laboratoire de Chimie Théorique, Université Pierre et Marie Curie, 75005 Paris (France); Head-Gordon, Martin [Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2013-10-28

140

The role of Rydberg and continuum levels in computing high harmonic generation spectra of the hydrogen atom using time-dependent configuration interaction.  

PubMed

We study the role of Rydberg bound-states and continuum levels in the field-induced electronic dynamics associated with the High-Harmonic Generation (HHG) spectroscopy of the hydrogen atom. Time-dependent configuration-interaction (TD-CI) is used with very large atomic orbital (AO) expansions (up to L = 4 with sextuple augmentation and off-center functions) to describe the bound Rydberg levels, and some continuum levels. To address the lack of ionization losses in TD-CI with finite AO basis sets, we employed a heuristic lifetime for energy levels above the ionization potential. The heuristic lifetime model is compared against the conventional atomic orbital treatment (infinite lifetimes), and a third approximation which is TD-CI using only the bound levels (continuum lifetimes go to zero). The results suggest that spectra calculated using conventional TD-CI do not converge with increasing AO basis set size, while the zero lifetime and heuristic lifetime models converge to qualitatively similar spectra, with implications for how best to apply bound state electronic structure methods to simulate HHG. The origin of HHG spectral features including the cutoff and extent of interference between peaks is uncovered by separating field-induced coupling between different types of levels (ground state, bound Rydberg levels, and continuum) in the simulated electronic dynamics. Thus the origin of deviations between the predictions of the semi-classical three step model and the full simulation can be associated with particular physical contributions, which helps to explain both the successes and the limitations of the three step model. PMID:24182018

Luppi, Eleonora; Head-Gordon, Martin

2013-10-28

141

The role of Rydberg and continuum levels in computing high harmonic generation spectra of the hydrogen atom using time-dependent configuration interaction  

NASA Astrophysics Data System (ADS)

We study the role of Rydberg bound-states and continuum levels in the field-induced electronic dynamics associated with the High-Harmonic Generation (HHG) spectroscopy of the hydrogen atom. Time-dependent configuration-interaction (TD-CI) is used with very large atomic orbital (AO) expansions (up to L = 4 with sextuple augmentation and off-center functions) to describe the bound Rydberg levels, and some continuum levels. To address the lack of ionization losses in TD-CI with finite AO basis sets, we employed a heuristic lifetime for energy levels above the ionization potential. The heuristic lifetime model is compared against the conventional atomic orbital treatment (infinite lifetimes), and a third approximation which is TD-CI using only the bound levels (continuum lifetimes go to zero). The results suggest that spectra calculated using conventional TD-CI do not converge with increasing AO basis set size, while the zero lifetime and heuristic lifetime models converge to qualitatively similar spectra, with implications for how best to apply bound state electronic structure methods to simulate HHG. The origin of HHG spectral features including the cutoff and extent of interference between peaks is uncovered by separating field-induced coupling between different types of levels (ground state, bound Rydberg levels, and continuum) in the simulated electronic dynamics. Thus the origin of deviations between the predictions of the semi-classical three step model and the full simulation can be associated with particular physical contributions, which helps to explain both the successes and the limitations of the three step model.

Luppi, Eleonora; Head-Gordon, Martin

2013-10-01

142

Single and collective regimes in three-level systems interacting with a one-mode electromagnetic field  

NASA Astrophysics Data System (ADS)

A semiclassical analysis is presented to determine the quantum phase transition from single to collective regimes in three-level atoms in the presence of a radiation field. The energy surfaces of the ?, V, and ? configurations are constructed by taking the expectation value with respect to U(3) coherent states that carry the totally symmetric representation, determined by the total number of atoms. The corresponding stability and equilibrium properties are calculated by means of the catastrophe theory, discovering the bifurcation and Maxwell sets. We establish that the atoms with ? and ? configurations have the presence of double points, i.e., there are two independent quantum states with the same energy that can be obtained depending on the values of the dipolar strengths of the interaction between the atoms and the radiation field. Additionally, the ? configuration exhibits a fixed triple point.

Castaños, O.; Cordero, S.; López-Peña, R.; Nahmad-Achar, E.

2014-05-01

143

Simulation of the temperature elevation in children exposed to plane wave electromagnetic fields (10 MHz-1 GHz) at the ICNIRP reference level.  

PubMed

Because of a lack of thermal models, to date, limitation of exposure to an electromagnetic field (EMF) has been based on restricting intracorporal specific absorption rates. To allow convenient compliance checks, reference field values have been defined. If they are met, compliance with basic restrictions is assumed. This article demonstrates that this assumption is not valid in every case. It has therefore been investigated as to whether the biological goal of limiting tissue heating is still met, in particular with regard to children. The thermal solver applied is based on the bioheat equation, with implemented additional improvements that allow consideration of blood flow and metabolic rate as a function of local tissue temperature rise and, in addition, adapt the blood temperature relative to the absorbed power. As a further improvement, heat exchange at the tissue/air boundary has been modeled, with radiation, convection, and sweating considered as well. The mathematical equations describing these additional thermoregulatory mechanisms were taken from the literature and unified in the thermoregulatory model used for this study. For the investigated case of plane wave exposure, the results confirm the violation of the basic restrictions in five of the six models when exposed to reference EMF levels. However, using thermal modeling, it was possible to demonstrate that heating remained within the biological tolerances. In particular, temperature elevation of the body core temperature remained <0.014°C and the local peak temperature did not exceed 1°C. PMID:22691427

Niedermayr, Florian; Leitgeb, Norbert; Siegl, Werner

2012-06-01

144

Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field.  

PubMed

The exposure of primary rat neocortical astroglial cell cultures to acute electromagnetic fields (EMF) in the microwave range was studied. Differentiated astroglial cell cultures at 14 days in vitro were exposed for 5, 10, or 20min to either 900MHz continuous waves or 900MHz waves modulated in amplitude at 50Hz using a sinusoidal waveform and 100% modulation index. The strength of the electric field (rms value) at the sample position was 10V/m. No change in cellular viability evaluated by MTT test and lactate dehydrogenase release was observed. A significant increase in ROS levels and DNA fragmentation was found only after exposure of the astrocytes to modulated EMF for 20min. No evident effects were detected when shorter time intervals or continuous waves were used. The irradiation conditions allowed the exclusion of any possible thermal effect. Our data demonstrate, for the first time, that even acute exposure to low intensity EMF induces ROS production and DNA fragmentation in astrocytes in primary cultures, which also represent the principal target of modulated EMF. Our findings also suggest the hypothesis that the effects could be due to hyperstimulation of the glutamate receptors, which play a crucial role in acute and chronic brain damage. Furthermore, the results show the importance of the amplitude modulation in the interaction between EMF and neocortical astrocytes. PMID:20156525

Campisi, Agata; Gulino, Marisa; Acquaviva, Rosaria; Bellia, Paolo; Raciti, Giuseppina; Grasso, Rosaria; Musumeci, Francesco; Vanella, Angelo; Triglia, Antonio

2010-03-31

145

Simultaneous Analysis of the Rovibrational Levels ? 4=1, 2, and 3 of HCCI and DCCI Based on Infrared Spectra  

NASA Astrophysics Data System (ADS)

The energy levels ? 4=1, ? 4=2, and ? 4=3 of DCCI have been analyzed by using the fundamental ? 41 (470-520 cm -1) and the overtone 2? 40 (955-1005 cm -1) bands together with the hot bands 2? 40,2?? 41, 3? 41,3?2? 40,2, and 3? 41?? 41. In the case of HCCI the previously studied hot bands connected to ? 4 have been completed by adding 3? 41?? 41 into the analysis. The various l-type resonances have been taken into account in the analyses of both the isotopomers. Furthermore, the Coriolis resonance between the close-lying ? 3 and ? 4 of DCCI has been considered. Altogether, accurate values for the molecular constants and the resonance parameters have been obtained from simultaneous analysis and they have been compared with those from separate analyses for different levels.

Sarkkinen, H.

2001-06-01

146

Local field effects and multi-peak spectra in coherent scattering of resonant light in a two-level medium  

Microsoft Academic Search

Scattering of a laser pulse is considered in a dense medium with account for local field effects. The interacting system of\\u000a two-level atoms and quantized field modes is studied in the second Born approximation of the Bogolyubov-Born-Green-Kirkwood-Yvon\\u000a hierarchy of equations for reduced density and correlation operators. The local field correction is derived consistently from\\u000a the conventional interaction Hamiltonian and adjusted

Maxim G. Gladllsh; Alexey A. Panteleev; Vladimir K. Roerich

2006-01-01

147

Evidence for replicate 5p core levels in photoelectron spectra of Eu metal due to nonconstant kinetic-energy resonant Auger decay  

SciTech Connect

Satellites on the low-binding-energy side of core-level photoelectron emission due to extra 4f screening are a well-known feature in the x-ray photoelectron spectra of valence fluctuation materials and rare-earth metals. A notable exception is Eu metal, where up to now no low-binding-energy satellite has been observed. In this paper we show that in Eu metal the 4d-4f resonance can decay via a resonant Auger decay, which is not a constant kinetic-energy feature due to a rapid change of the strength of 4f screening with excitation energy, establishing a low-binding-energy replica of the 5p core-level photoelectron emission. (c) 1999 The American Physical Society.

Haffner, S. [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States); Olson, C. G. [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States); Lynch, D. W. [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Physics and Ames Laboratory, U. S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States)

1999-12-15

148

Strong permanent magnet-assisted electromagnetic undulator  

SciTech Connect

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.

Halbach, Klaus (Berkeley, CA)

1988-01-01

149

180Hf energy levels deduced from thermal and average resonance neutron-capture gamma-ray spectra  

Microsoft Academic Search

An energy level diagram for 180Hf is developed on the basis of neutron-capture gamma-ray spectroscopy. Both thermal neutron capture and average resonance neutron-capture studies were made with isotopically enriched and natural Hf samples. The energies and intensities of the high-energy 7.4-4.7 MeV primary gamma transitions and the intermediate-energy 2.1-0.5 MeV gamma transitions were made with the in-pile (n ,gamma) source

D. L. Bushnell; D. J. Buss; Robert K. Smither

1974-01-01

150

Parmeterization of spectra  

NASA Technical Reports Server (NTRS)

Following reception and analog to digital conversion (A/D) conversion, atmospheric radar backscatter echoes need to be processed so as to obtain desired information about atmospheric processes and to eliminate or minimize contaminating contributions from other sources. Various signal processing techniques have been implemented at mesosphere-stratosphere-troposphere (MST) radar facilities to estimate parameters of interest from received spectra. Such estimation techniques need to be both accurate and sufficiently efficient to be within the capabilities of the particular data-processing system. The various techniques used to parameterize the spectra of received signals are reviewed herein. Noise estimation, electromagnetic interference, data smoothing, correlation, and the Doppler effect are among the specific points addressed.

Cornish, C. R.

1983-01-01

151

Personal radiofrequency electromagnetic field measurements in The Netherlands: exposure level and variability for everyday activities, times of day and types of area.  

PubMed

Knowledge of the exposure to radiofrequency electromagnetic fields is necessary for epidemiological studies on possible health effects. The main goal of this study is to determine the exposure level and spatial and temporal variances during 39 everyday activities in 12 frequency bands used in mobile telecommunication and broadcasting. Therefore, 24 h measurements were gathered from 98 volunteers living in or near Amsterdam and Purmerend, The Netherlands. They carried an activity diary to be kept to the minute, a GPS logger sampling at an interval of 1 s, and an EME Spy exposimeter with a detection limit of 0.0066 mW/m(2) sampling at an interval of 10s in 12 frequency bands. The mean exposure over 24 h, excluding own mobile phone use, was 0.180 mW/m(2). During daytime exposure was about the same, but during night it was about half, and in the evening it was about twice as high. The main contribution to environmental exposure (calling by participant not included) is from calling with mobile phones (37.5%), from cordless DECT phones and their docking stations (31.7%), and from the base stations (12.7%). The exposure to mobile phone base stations increases with the percentage of urban ground use, which is an indication for high people density. In agreement, the highest mean exposure relates to the activities with high people density, such as travelling by public transport, visiting social events, pubs or shopping malls. Exposure at home depends mainly on exposure from people calling in the neighbourhood of the participant and thus on the number of persons in a household. In addition just the possession of DECT docking stations leads to exposure as most models transmit continuously in stand-by. Also wireless internet routers continuously transmit in the WiFi band. Though the highest exposure peaks in the WiFi band, up to 0.265 W/m(2), come from stray radiation of microwave ovens. The mean total exposure largely depends on phone calls of a high exposure level and short duration. These calls lead to potentially high contrasts as well in exposure levels between sessions of the same activity as between persons, thus posing a challenge for personal exposure prediction. PMID:22906414

Bolte, John F B; Eikelboom, Tessa

2012-11-01

152

Steps Towards a Fully Automated Classification and Redshift-measurement Pipeline for LAMOST Spectra. I. Continuum level and wavelength estimation for galaxies  

NASA Astrophysics Data System (ADS)

The Large Sky-Area Multi-Object Spectroscopic Telescope (LAMOST) under construction by the National Astronomical Observatories will yield up to four thousand multi-fiber spectra of stars and galaxies per field. The present series of papers describes the automated data-reduction pipeline currently being designed in order to cope with the anticipated flood of spectrographic data. In this preliminary paper, we present an automated method for estimating the continuum level, the positions of strong lines and the 4000 Å break in galaxy spectra. In order to obtain detailed information on the continuum, we use a wavelet filter bank. After continuum fitting, our software searches for a 4000 Å break and distinguishes between emission-line galaxies (ELGs) and non-ELGs according to whether the break is small or large. It then searches for strong lines and measures the intensities of emission lines and the equivalent widths of absorption lines. For non-ELGs, the absorption lines are identified automatically yielding redshift measurements.

Luo, A.-Li; Zhao, Yong-Heng

2001-12-01

153

Efficient two-dimensional atom localization via phase-sensitive absorption and gain spectra in a cycle-configuration four-level atomic system  

NASA Astrophysics Data System (ADS)

A scheme of two-dimensional atom localization is proposed based on the phase-sensitive probe absorption and gain in a four-level atomic system with a closed-loop configuration. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting absorption and gain spectra of the weak probe laser field. It is found that the phase-sensitive property of the atomic system significantly improves the localization behavior. Especially the maximal probability of finding the atom at a particular position within the sub-wavelength domain of the standing waves can arrive at unity by appropriate choice of the system parameters.

Zhang, Duo; Yu, Rong; Li, Jiahua; Hao, Xiangying; Yang, Xiaoxue

2014-06-01

154

Creating an Electromagnet  

NSDL National Science Digital Library

Student teams investigate the properties of electromagnets. They create their own small electromagnet and experiment with ways to change its strength to pick up more paper clips. Students learn about ways that engineers use electromagnets in everyday applications.

Integrated Teaching And Learning Program

155

Electromagnetic microactuators  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

156

Electromagnetic radiation generated by arcing in low density plasma  

NASA Technical Reports Server (NTRS)

An unavoidable step in the process of space exploration is to use high-power, very large spacecraft launched into Earth orbit. Obviously, the spacecraft will need powerful energy sources. Previous experience has shown that electrical discharges occur on the surfaces of a high-voltage array, and these discharges (arcs) are undesirable in many respects. Moreover, any high voltage conductor will interact with the surrounding plasma, and that interaction may result in electrical discharges between the conductor and plasma (or between two conductors with different potentials, for example, during docking and extravehicular activity). One very important aspect is the generation of electromagnetic radiation by arcing. To prevent the negative influence of electromagnetic noise on the operation of spacecraft systems, it seems necessary to determine the spectra and absolute levels of the radiation, and to determine limitations on the solar array bias voltage that depend on the parameters of LEO plasma and the technical requirements of the spacecraft equipment. This report describes the results of an experimental study and computer simulation of the electromagnetic radiation generated by arcing on spacecraft surfaces. A large set of high quality data was obtained during the Solar Array Module Plasma Interaction Experiment (SAMPIE, flight STS-62) and ground test. These data include the amplitudes of current, pulse forms, duration of each arc, and spectra of plasma waves. A theoretical explanation of the observed features is presented in this report too. The elaborated model allows us to determine the parameters of the electromagnetic noise for different frequency ranges, distances from the arcing site, and distinct kinds of plasma waves.

Vayner, Boris V.; Ferguson, Dale C.; Snyder, David B.; Doreswamy, C. V.

1996-01-01

157

Electromagnetic valve  

US Patent & Trademark Office Database

In an electromagnetic valve, a composite valve case has a cylindrical hollow and a composite valve body formed in spool shape is slidably housed in the cylindrical hollow. The composite valve body has not only an inherent valve function for changing fluid path area according to its movement in the cylindrical hollow but also an armature function for constituting a magnetic circuit. The composite valve case has not only a cylinder function for allowing the valve body to slidably move but also a stator function for constituting a magnetic circuit. The composite valve body and the composite valve case are made of soft magnetic material and are provided at their surfaces with thin hardened layers formed by surface or heat treatment.

2003-12-30

158

Transient electromagnetic interference in substations  

Microsoft Academic Search

Electromagnetic interference levels on sensitive electronic equipment are quantified experimentally and theoretically in air and gas insulated substations of different voltages. Measurement techniques for recording interference voltages and currents and electric and magnetic fields are reviewed and actual interference data are summarized. Conducted and radiated interference coupling mechanisms and levels in substation control wiring are described using both measurement results

C. M. Wiggins; D. E. Thomas; F. S. Nickel; T. M. Salas; S. E. Wright

1994-01-01

159

Relaxation of vibrational levels H2O (002, 101, 200): effect of new rate constants on the H2O vibrational level populations and ro-vibrational spectra in the mesosphere and lower thermosphere  

NASA Astrophysics Data System (ADS)

In this work, we investigate the sensitivity of the H2O vibrational level populations and ro-vibrational spectra in the mesosphere and lower thermosphere (MLT) to new values of rate constants for the collision-induced transitions from the upper vibrational levels of H2O molecule. This study contributes to the development of the H2O non-equilibrium radiation model used for water vapor altitude distribution retrieval from the MLT radiation measurements. Our model accounts for 13 excited vibrational states up to energies 7445 cm-1 (the upper levels are 002, 101, 200) [Feofilov et al., 2009]. The model takes into account 54 vibrational-translational (V-T) and vibrational-vibrational (V-V) energy exchange processes at collisions of H2O with N2, O2 and O. The 32 ro-vibrational transitions forming 1.4, 1.9, 2.7, 3.2, 4.7 and 6.3 ?m water vapor radiation bands are considered. Currently, the rate constants of intermolecular transitions between vibrational levels at collisions with N2 and O2 are known only for the transitions (010-000) and (001,100-020). In our model of H2O vibrational level kinetics [Feofilov et al., 2009], we assumed that for all collisional transitions, at which the bending mode quantum number, v2, increases by 2: H2O(v1,v2,v3) + M = H2O(v1-1,v2+2,v3) + M H2O(v1,v2,v3) + M = H2O(v1,v2+2,v3-1) + M (1) the rate constants are equal to that of the process H2O(001, 100) + M = H2O(020) + M. Based on the analysis of currently available experimental and theoretical data, we have updated k, the rate constant of transitions (002, 101)?021 and (101, 200)?120, and estimated the effect of a new rate on the H2O vibrational levels populations and limb radiation spectra. The "upper limit" of the effect was estimated using the same rate constant k for all processes of type (1), excluding process (001, 100)?020. The H2O vibrational levels populations and limb radiation spectra were calculated using the ALI-ARMS non-LTE code [Kutepov et al. 1998; Feofilov and Kutepov, 2012] for characteristic atmospheric conditions and compared with the populations and spectra obtained for "regular" rate constants used in [Feofilov et al., 2009]. References Feofilov A. G., Kutepov A. A., Pesnell W. D., Goldberg R. A., Marshall B. T., Gordley L. L., Garcia-Comas M., Lopez-Puertas M., Manuilova R. O., Yankovsky V. A., Petelina S. V., Russell J. M. III. Daytime SABER/TIMED observations of water vapor in the mesosphere: retrieval approach and first results, Atmospheric Chemistry and Physics, V 9, N 21, P 8139-8158, 2009. Kutepov, A. A., Gusev, O. A., and Ogibalov, V. P., Solution of the non-LTE problem for molecular gas in planetary atmospheres: Superiority of accelerated lambda iteration, J. Quant. Spectrosc. Radiat. Transf. V 60, P 199, 1998. Feofilov, A.G., and Kutepov, A., A., "Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing", Surveys in Geophysics, doi:10.1007/s10712-012-9204-0, 2012.

Manuilova, Rada; Feofilov, Artem; Kutepov, Alexander; Yankovsky, Valentine

2014-05-01

160

High-resolution infrared absorption spectra, crystal-field levels, and relaxation processes in CsCdBr3:Pr3+  

NASA Astrophysics Data System (ADS)

High-resolution low-temperature absorption spectra of 0.2% Pr3+-doped CsCdBr3 were measured in the spectral region 2000-7000 cm-1. Positions and widths of the crystal-field levels within the 3H5, 3H4, 3F2, and 3F3 multiplets of the Pr3+ main center have been determined. The hyperfine structure of several spectral lines has been found. Crystal-field calculations were carried out in the framework of the semiphenomenological exchange charge model (ECM). Parameters of the ECM were determined by fitting to the measured total splittings of the 3H4 and 3H6 multiplets and to the observed hyperfine splittings of the crystal-field levels in this work. One- and two-phonon relaxation rates were calculated using the phonon Green's functions of the perfect (CsCdBr3) and locally perturbed (impurity dimer centers in CsCdBr3:Pr3+) crystal lattice. Comparison with the measured linewidths confirmed an essential redistribution of the phonon density of states in CsCdBr3 crystals doped with rare-earth ions.

Popova, M. N.; Chukalina, E. P.; Malkin, B. Z.; Iskhakova, A. I.; Antic-Fidancev, E.; Porcher, P.; Chaminade, J. P.

2001-02-01

161

DISPLACEMENT SPECTRA FOR SEISMIC DESIGN  

Microsoft Academic Search

Displacement-based seismic design and assessment of structures require the reliable definition of displacement spectra for a wide range of periods and damping levels. The displacement spectra derived from acceleration spectra in existing seismic codes do not provide a suitable answer and there are no existing frequency-dependent attenuation relationships derived specifically for this purpose. Using a carefully processed dataset of European

JULIAN J. BOMMER; AMR S. ELNASHAI

1999-01-01

162

Dynamics of fundamental electromagnetic emission via beam-driven Langmuir waves  

SciTech Connect

The nonlinear process of electromagnetic Langmuir decay, which leads to radio emission near the plasma frequency, is studied for situations in which Langmuir waves are directly driven by an electron beam and indirectly generated via electrostatic Langmuir decays. The electromagnetic Langmuir decay is stimulated by the presence of ion-acoustic waves. An approximate method is devised for studying this emission process with axial symmetry (along the direction of beam propagation) in three spatial dimensions, based upon the Langmuir and ion-acoustic wave dynamics in one spatial dimension. Numerical studies of the fundamental electromagnetic emission starting from electron dynamics are then carried out via quasilinear theory, and the results are explored for illustrative parameters. The evolution of the fundamental transverse waves shows the combined effects of local emission and propagation away from the source. At a given location, the emission rate shows a series of peaks associated with successive electromagnetic decays of the Langmuir waves, which are either driven by the beam or produced by successive electrostatic decays. The emission rate for a given electromagnetic decay decreases with time, following an initial increase. In addition, the emission rate for a specific electromagnetic decay shows approximate dipolar form, consistent with previous analytical work. Consequently, the fundamental transverse waves emitted locally propagate approximately symmetrically in both the forward and the backward directions. Variation of the background electron to ion temperature ratio, beam injection parameters, and angular widths of the Langmuir and ion-acoustic spectra are found to affect the emission rate and, hence, the fundamental transverse wave levels. Furthermore detailed studies show that the wave numbers of the maximum emission rates are also in good agreement with an approximate prediction for simple model Langmuir and ion-acoustic spectra.

Li, B.; Willes, A.J.; Robinson, P.A.; Cairns, I.H. [School of Physics, University of Sydney, New South Wales 2006 (Australia)

2005-05-15

163

Gravito-electromagnetic resonances in Minkowski space  

NASA Astrophysics Data System (ADS)

We consider the interaction between gravitational and electromagnetic radiation propagating on a Minkowski background and look into the effects of the former upon the latter. Not surprisingly, the coupling between these two sources leads to gravitationally driven electromagnetic waves. At the second perturbative level, the driving force appears as the superposition of two waves, the properties of which are decided by the initial conditions. We find that the Weyl-Maxwell interaction typically leads to electromagnetic beatlike signals and, in some cases, to the resonant amplification of the driven electromagnetic wave. For physically reasonable initial conditions, we show that these resonances imply a linear (in time) growth for the amplitude of the electromagnetic signal, with the overall amplification also depending on the strength of the driving gravity wave. Finally, we provide order-of-magnitude estimates of the achieved amplification by applying our analysis to astrophysical environments where both gravitational and electromagnetic waves are expected to coexist.

Kouretsis, Alexandros P.; Tsagas, Christos G.

2013-08-01

164

Thermodynamic analysis of spectra  

SciTech Connect

Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra--the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the {delta}{sub 3} statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic 'internal energy' and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is {delta}{sub 3}, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

Mitchell, G. E. [North Carolina State University, Raleigh, NC 27695 and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Shriner, J. F. Jr. [Tennessee Technological University, Cookeville, TN 38505 (United States)

2008-04-04

165

The effect of electromagnetic fields on oxidative DNA damage  

Microsoft Academic Search

Many recent studies have focused on the investigation of the biological effects of electromagnetic field. Although the several types of biological effects of electromagnetic fields have been shown, the molecular mechanisms of these effects have not been explained yet. Some epidemiological studies have suggested that exposure to ambient, low- level 50-60 Hz electromagnetic fields increase risk of disease including cancer

166

Experimental investigation of the ionospheric hysteresis effect on the threshold excitation level of the Stimulated Electromagnetic Emission (SEE) during heating at the second electron gyro-harmonic frequency  

NASA Astrophysics Data System (ADS)

Recent experimental observations of the stimulated electromagnetic emission (SEE) spectrum during heating at the second electron gyro-harmonic show structures ordered by ion gyro-frequency. The proposed generation mechanism considers parametric decay of a pump upper hybrid/electron Bernstein (UH/EB) wave into another UH/EB and a group of neutralized ion Bernstein waves. The presumption of the proposed mechanism is that the pump electromagnetic wave is converted into the UH/EB wave. This conversion process generates field aligned irregularity which exhibits hysteresis effect. The predicted ionospheric hysteresis effect is studied during the PARS 2012 at HAARP. The preliminary results are presented for the first time. Also, experimental study of the effects of 1) the transmitter beam angle and 2) the transmitter frequency offset relative to the second electron gyro-harmonic frequency on the ion gyro-harmonic structures in the SEE spectrum are provided. The aforementioned observations are compared to the predictions of the analytical model. Possible connection of the SEE spectral features and artificially generated ionospheric descending layer is also discussed

Samimi, A.; Scales, W.; Cruz, M.; Isham, B.; Bernhardt, P. A.

2012-12-01

167

Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

2007-01-01

168

Power electronics and electromagnetic compatibility  

Microsoft Academic Search

Recently, power electronics has become the dominant factor in the deterioration of the electromagnetic environment, causing declining quality of line power and increasing level of conducted EMI. This paper reviews the fundamentals of EMC in power electronics, including the terminology and categories of EMC, the propagation and generation of low-frequency and high-frequency disturbances, and the various agency regulations. The paper

R. Redl

1996-01-01

169

Electromagnetic propulsion for spacecraft  

NASA Technical Reports Server (NTRS)

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.

Myers, Roger M.

1993-01-01

170

Fluorescence Spectra  

NSDL National Science Digital Library

This experiment uses the Tracker video analysis and modeling tool to explore the phenomenon of fluorescence and its application in fluorescent lamps. For each of five different visible spectra, students (a) observe the spectrum directly, (b) measure its brightness versus wavelength in Tracker, and (c) answer both qualitative and quantitative questions about it. The spectra include a fluorescent dye with laser and UV illumination, a mercury lamp and two fluorescent lamps, all with red and green laser spots added for easy calibration. For more information, see the AAPT presentation. The zip file includes the lab instructions, spectrum images and Tracker data files. This requires Tracker version 4.62 or higher. Tracker installers are available for Windows, Mac and Linux from ComPADRE or the Tracker web site (http://www.cabrillo.edu/~dbrown/tracker/).

Brown, Douglas

2012-01-17

171

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This web site contains materials about all parts of the electromagnetic spectrum. It describes each space telescope that NASA has launched as well as its observing range in the electromagnetic spectrum.

Astrophysics, Laboratory F.

2004-11-17

172

Action of an electromagnetic pulse on a plasma with a high level of ion-acoustic turbulence. Field diffusion and subdiffusion  

NASA Astrophysics Data System (ADS)

Specific features of the interaction of a relatively weak electromagnetic pulse with a nonisothermal current-carrying plasma in which the electron drift velocity is much higher than the ion-acoustic velocity, but lower than the electron thermal velocity, are studied. If the state of the plasma with ion-acoustic turbulence does not change during the pulse action, the field penetrates into the plasma in the ordinary diffusion regime, but the diffusion coefficient in this case is inversely proportional to the anomalous conductivity. If, during the pulse action, the particle temperatures and the current-driving field change due to turbulent heating, the field penetrates into the plasma in the subdiffusion regime. It is shown how the presence of subdiffusion can be detected by measuring the reflected field.

Ovchinnikov, K. N.; Uryupin, S. A.

2013-09-01

173

Action of an electromagnetic pulse on a plasma with a high level of ion-acoustic turbulence. Field diffusion and subdiffusion  

SciTech Connect

Specific features of the interaction of a relatively weak electromagnetic pulse with a nonisothermal current-carrying plasma in which the electron drift velocity is much higher than the ion-acoustic velocity, but lower than the electron thermal velocity, are studied. If the state of the plasma with ion-acoustic turbulence does not change during the pulse action, the field penetrates into the plasma in the ordinary diffusion regime, but the diffusion coefficient in this case is inversely proportional to the anomalous conductivity. If, during the pulse action, the particle temperatures and the current-driving field change due to turbulent heating, the field penetrates into the plasma in the subdiffusion regime. It is shown how the presence of subdiffusion can be detected by measuring the reflected field.

Ovchinnikov, K. N.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2013-09-15

174

Electromagnetic Interference (Emi)  

Microsoft Academic Search

\\u000a Electric and magnetic signals originating outside of a defibrillator may affect its operation, a phenomenon known as electromagnetic\\u000a interference (EMI). EMI usually refers to interference from environmental electromagnetic instrumentation and should be distinguished\\u000a from other sources of electromagnetic noise causing ICD malfunction (Table 1). Signals most likely to penetrate and affect\\u000a pacemakers and ICDs are electromagnetic waves or signals at

Mike Hardage; Philip D. Henry

175

Electromagnetic environmental effects compendium  

NASA Astrophysics Data System (ADS)

This report summarizes the electromagnetic environmental effects (E3) program of the U.S. Army Communications-Electronics Command (CECOM). The report includes background information on CECOM's role in the Army E3 program, presents the approach used to identify the electromagnetic environment, summarizes E3 criteria (i.e., the CECOM model electromagnetic environment), and provides a sample E3 assessment. The report also discusses electromagnetic trends and their implications.

Brockel, Kenneth H.; Cofield, David; Deallaume, William; Gorr, Lanny; Major, Paul A.

1993-08-01

176

Electromagnetic particle simulation codes  

Microsoft Academic Search

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

P. L. Pritchett

1985-01-01

177

The electromagnetic spike solutions  

NASA Astrophysics Data System (ADS)

The aim of this paper is to use the existing relation between polarized electromagnetic Gowdy spacetimes and vacuum Gowdy spacetimes to find explicit solutions for electromagnetic spikes by a procedure which has been developed by one of the authors for gravitational spikes. We present new inhomogeneous solutions which we call the EME and MEM electromagnetic spike solutions.

Nungesser, Ernesto; Lim, Woei Chet

2013-12-01

178

Composite electromagnetic pulse threat  

Microsoft Academic Search

A new electromagnetic pulse threat that is based on a composite ambient field defined by a combination of lightning, NEMP (nuclear electromagnetic pulse) and microwave threats is discussed. The composite electromagnetic pulse threat has been used to harden a military helicopter. The hardening to a composite threat resulted in the development of simplified hardening verification procedures. It also provided an

Andrew S. Podgorski

1990-01-01

179

Composite electromagnetic pulse threat  

Microsoft Academic Search

A new electromagnetic pulse threat based on a composite ambient field defined by a combination of lightning, NEMP (nuclear electromagnetic pulse) and microwave threats is discussed. The composite electromagnetic pulse threat has been used to harden a military helicopter. The hardening to a composite threat resulted in the development of simplified hardening verification procedures. It also provided an economical advantage

A. S. Podgorski

1990-01-01

180

Atomic Spectra Database (ASD)  

National Institute of Standards and Technology Data Gateway

SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

181

Gallium Electromagnetic (GEM) Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

2009-01-01

182

The Study on Experiment and Mechanism of Sterilization with Electromagnetic Wave  

Microsoft Academic Search

The phenomenon of variation caused by interactions between the electromagnetic field and the biologic system in modality, configuration, function and other aspects of different biologic levels is called the biological effect of electromagnetic field. The sterilization effects of the constant electromagnetic wave and the instant electromagnetic pulse acting on the edible sauce and the Chinese medical pills are introduced in

Z. Y. Lu; H. Ding; W. Q. Sun; P. P. Andshi

2007-01-01

183

Electromagnetic Radiation: On Trial  

NSDL National Science Digital Library

This activity introduces students to the properties of electromagnetic radiation in a variety of ways. For example, they put the different types of the electromagnetic radiation on trial, selecting the judge, prosecutor, defense counsel, and jury, and learning about electromagnetic energy by arguing the pros and cons of each wavelength. During this activity, students are introduced to the general properties of electromagnetic waves, learn to analyze the relation between the specific properties of waves and their position in the electromagnetic spectrum, and discuss methods used to detect and analyze different waves. Students also learn about scientists whose work contributed to our understanding of electromagnetic energy. Students are encouraged to use an electronic bulletin board to communicate with each other, posting insights, ideas, evidence and questions on electromagnetic energy.

184

A strong permanent magnet-assisted electromagnetic undulator  

SciTech Connect

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. 4 figs.

Halbach, K.

1987-01-30

185

Optical spectra, energy levels, and crystal-field analysis of tripositive rare-earth ions in Y2O3. IV. C3i sites  

Microsoft Academic Search

We report an analysis of new and previously existing optical absorption and fluorescence data, far-infrared data, and electronic Raman scattering data for Eu3+, Dy3+, and Er3+ in the C3i sites of Y2O3 and R2O3, where R=a rare earth. Our previous analysis of C2-site spectra yields an effective point-charge model for the host lattice that allows initial estimates to be calculated

John B. Grubers; Richard P. Leavitt; Clyde A. Morrison; N. C. Chang

1985-01-01

186

Energy levels and predicted absorption spectra of rare-earth ions in rare-earth arsenides. Interim report, 1 July30 September 1992  

Microsoft Academic Search

A crystal-field Hamiltonian for octahedral symmetry was used along with free-ion parameters for aqueous solution to fit the reported optical absorption spectra of Er(3+) in ErAs. Predictions showed excellent agreement with reported experimental data at so 74, and 300 K. Consequently, we used an interpolation procedure to predict the crystal-field splittings of the lower multiplets of the rare-earth ions Tb(3+)

D. E. Wortman; C. A. Morrison

1992-01-01

187

Optical spectra, energy levels, and crystal-field analysis of tripositive rare earth ions in Y2O3. I. Kramers ions in C2 sites  

Microsoft Academic Search

Optical absorption and fluorescence spectra of the Kramers ions Ce3+, Sm3+, Dy3+, and Yb3+ in the C2 sites of Y2O3 are reported. A crystal-field analysis of these data and previously reported data for Nd3+ and Er3+ is performed that is based on a Hamiltonian of C2 point-group symmetry, including J-mixing effects. A best-fit analysis is performed for the ions Nd3+,

N. C. Chang; John B. Gruber; Richard P. Leavitt; Clyde A. Morrison

1982-01-01

188

Electromagnetic structure of pion  

SciTech Connect

In this work, we analyze the electromagnetic structure of the pion, an elementary particle composed by a quark-antiquark bound state, by considering the calculation of its electromagnetic radius and its electromagnetic form factor in low and intermediate energy range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion, in the formalism of the light-front field theory. In particular, it is considered a nonsymmetrical vertex for such a model, in which we have calculated the electromagnetic form factor of the pion in an optimized way, by varying its regulator mass, so that we can obtain the best value for the pion electromagnetic radius when compared with the experimental one. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

Mello, Clayton S.; Cruz Filho, Jose P.; Da Silva, Edson O.; El-Bennich, Bruno; De Melo, J. P.; Filho, Victo S. [Laboratorio de Fisica Teorica e Computacional (LFTC), Universidade Cruzeiro do Sul, 01506-000, Sao Paulo (Brazil)

2013-03-25

189

First-principles and experimental analysis of fn-fn-1d1 absorption spectra and multiplet energy levels of Pr3+ , Nd3+ , and U3+ in LiYF4  

NASA Astrophysics Data System (ADS)

We performed experimental and theoretical investigation of the fn-fn-1d1 transitions of Pr3+ , Nd3+ , and U3+ in LiYF4 . The 4f2-4f15d1 absorption spectra for Pr3+ in LiYF4 and the 4f3-4f25d1 absorption spectra for Nd3+ in LiYF4 were measured using a synchrotron radiation light source at several different temperatures while the 5f3-5f26d1 absorption spectra for U3+ in LiYF4 referred to report of Hubert The multiplet energy levels and fn-fn-1d1 absorption spectra were calculated by a first-principles four-component relativistic configuration-interaction method. For all calculations of Nd3+ and U3+ in LiYF4 , we used the Dirac-Coulomb-Breit Hamiltonian and the molecular spinors obtained from the relativistic Vosko-Wilk-Nusair potential. The overall features of the theoretical absorption spectra of both Nd3+ and U3+ in LiYF4 reproduced the experimental features well. The origins of the experimental absorption spectra were clarified by performing a configuration analysis based on the many-electron wave functions. The splitting between peaks were affected by both spin-orbit interaction of f orbitals and crystal-field splitting of d orbitals. We found that the oscillator strengths of the 4f3-4f25d1 transition for Nd3+ in LiYF4 are slightly larger than those of the 5f3-5f26d1 transition for U3+ in LiYF4 . The experimental absorption spectra for Nd3+ in LiYF4 measured at nine different temperatures indicated that the 4f3-4f25d1 absorption spectra for Nd3+ in LiYF4 have no significant temperature dependence. For Pr3+ in LiYF4 , we performed more detailed investigations. The lattice relaxation effects due to the substitution of Y3+ by Pr3+ were estimated using a first-principles density-functional calculation. Structural optimization calculations indicated that the local structure of the Pr3+ site was slightly distorted. Overall, the theoretical 4f2-4f15d1 absorption spectra reproduced the experimental spectra. The experimental absorption spectra were investigated by configuration analysis based on the many-electron wave functions. The theoretical calculations indicated that the temperature dependence of the experimental spectra was due to both thermal excitation and phonon effects. In addition, we also investigated the effects of the exchange-correlation interaction and the Breit term by comparing the results from six different Hamiltonians.

Watanabe, Shinta; Ogasawara, Kazuyoshi; Yoshino, Masahito; Nagasaki, Takanori

2010-03-01

190

Genetic Effects of Electromagnetic Waves  

NASA Astrophysics Data System (ADS)

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.

Aroutiounian, Rouben; Hovhannisyan, Galina; Gasparian, Gennady

191

Electromagnetic fields stress living cells  

Microsoft Academic Search

Electromagnetic fields (EMF), in both ELF (extremely low frequency) and radio frequency (RF) ranges, activate the cellular stress response, a protective mechanism that induces the expression of stress response genes, e.g., HSP70, and increased levels of stress proteins, e.g., hsp70. The 20 different stress protein families are evolutionarily conserved and act as ‘chaperones’ in the cell when they ‘help’ repair

Martin Blank; Reba Goodman

2009-01-01

192

How Strong are Electromagnets?  

NSDL National Science Digital Library

This is an activity about electromagnetism. Using a battery and a length of wire, learners will construct an electromagnet and investigate the number of paperclips the electromagnet can hold for an electromagnet with twenty loops of wire versus one with forty loops of wire. A six to twelve volt battery, a large nail or metal rod, and insulated wire are required for this activity. This is the fourth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

193

Second harmonic electromagnetic emission via beam-driven Langmuir waves  

SciTech Connect

The linked nonlinear processes of electrostatic Langmuir decay and electromagnetic emission at the second harmonic plasma frequency are studied for situations in which Langmuir waves are driven by an electron beam. An approximate method for studying wave decay and emission in three spatial dimensions is developed, based on the Langmuir and ion-acoustic wave dynamics in one spatial dimension. The numerical solutions of quasilinear equations to study electromagnetic emission starting from the electron dynamics are carried out. The numerical results are explored for illustrative parameters. The evolution of the transverse waves shows the combined effects of local emission and propagation away from the source. At a given location, the emission rate shows a series of peaks associated with coalescences of Langmuir waves driven by the beam and those produced by successive decays. The emission rate for a given coalescence decreases with time, following an initial increase. The effects of transverse wave propagation are illustrated by the presence of transverse waves both in regions upstream of the beam injection site due to backward propagation, and in regions downstream (e.g., where Langmuir waves are at thermal levels prior to the arrival of the beam) owing to forward propagation. Variation of the background electron to ion temperature ratio, beam injection parameters, and angular widths of the Langmuir spectra are found to affect the emission rate and the transverse wave levels. Furthermore, detailed studies show that the wave numbers of the maximum emission rates are in semiquantitative agreement with a previous theoretical prediction for simple model Langmuir spectra.

Li, B.; Willes, A.J.; Robinson, P.A.; Cairns, I.H. [School of Physics, University of Sydney, New South Wales 2006 (Australia)

2005-01-01

194

A comparison of lightning electromagnetic fields with the nuclear electromagnetic pulse in the frequency range 10 to the 4th to 10 to the 7th Hz  

Microsoft Academic Search

The electromagnetic fields produced by both direct lightning strikes and nearby lightning are compared with the nuclear electromagnetic pulse (NEMP) from an exoatmospheric burst. Model calculations indicate that, in the frequency range from 10 kHz to near 10 MHz, the Fourier amplitude spectra of the return stroke magnetic fields near ground 1 m from an average lightning strike will exceed

Martin Uman; Maneck Master; E. P. Krider

1982-01-01

195

Flame Spectra.  

ERIC Educational Resources Information Center

When salt (NaCl) is introduced into a colorless flame, a bright yellow light (characteristic of sodium) is produced. Why doesn't the chlorine produce a characteristic color of light? The answer to this question is provided, indicating that the flame does not excite the appropriate energy levels in chlorine. (JN)

Cromer, Alan

1983-01-01

196

Susceptibility of Civilian GPS Receivers to Electromagnetic Radiation  

Microsoft Academic Search

Civilian handheld global positioning system receivers were tested for their susceptibility against radiated electromagnetic disturbances of different characteristics and field levels. This susceptibility data were compared to the existing electromagnetic compatibility (EMC) immunity requirements for electronic devices. Some of the receivers were disrupted by continues waves at in- as well as out-of-band frequencies, at field levels far below the existing

D. Mansson; R. Thottappillil; T. Nilsson; O. Lunden; M. Backstrom

2008-01-01

197

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This is a lesson about the electromagnetic spectrum. Learners will read two pages of information about the electromagnetic spectrum and answer questions in an accompanying worksheet. This activity is from the Stanford Solar Center's All About the Sun: Sun and Stars activity guide for Grades 5-8 and can also accompany the Stanford Solar Center's Build Your Own Spectroscope activity.

198

Electromagnetic compatibility overview  

NASA Technical Reports Server (NTRS)

An assessment of the electromagnetic compatibility impact of the Satellite Power System is discussed. The discussion is divided into two parts: determination of the emission expected from SPS including their spatial and spectral distributions, and evaluation of the impact of such emissions on electromagnetic systems including considerations of means for mitigating effects.

Davis, K. C.

1980-01-01

199

Electromagnetic Analysis: Concrete Results  

Microsoft Academic Search

Abstract Although the possibility of attacking smart - cards by analyz - ing their electromagnetic power radiation repeatedly appears in research papers, all accessible references evade the essence of reporting conclusive experiments where actual cryptographic algorithms such as des or rsa were successfully attacked This work describes electromagnetic experiments conducted on three dif - ferent cmos chips, featuring di erent

Karine Gandolfi; Christophe Mourtel; Francis Olivier

2001-01-01

200

Electromagnetic shunt damping  

Microsoft Academic Search

A method for electromagnetic shunt damping (EMSD) is presented in this paper. Compared to piezoelectric shunt damping, the proposed EMSD vibration controller has a number of benefits. It requires small shunt voltages, can provide large stroke and can dampen larger mechanical structures. A passive control strategy is validated through experimentation on a simple electromagnetic mass-spring-damper system. Theoretical results are also

S. Behrens; A. J. Fleming; S. O. Reza Moheimani

2003-01-01

201

Tunability enhanced electromagnetic wiggler  

DOEpatents

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.

Schlueter, Ross D. (Albany, CA); Deis, Gary A. (Livermore, CA)

1992-01-01

202

Tunability enhanced electromagnetic wiggler  

DOEpatents

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.

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

1992-03-24

203

Building an Electromagnet  

NSDL National Science Digital Library

Students design and construct an electromagnet that must pick up 10 staples. They begin with only minimal guidance, and after the basic concept is understood, are informed of the properties that affect the strength of that magnet. They conclude by designing their own electromagnet to complete the challenge of separating scrap steel from scrap aluminum for recycling and share it with the class.

Vu Bioengineering Ret Program

204

Introducing Electromagnetic Field Momentum  

ERIC Educational Resources Information Center

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…

Hu, Ben Yu-Kuang

2012-01-01

205

Electronic spectra of adenine and 2-aminopurine: an ab initio study of energy level diagrams of different tautomers in gas phase and aqueous solution  

NASA Astrophysics Data System (ADS)

Ground and lowest two singlet excited state geometries of four tautomeric forms (N9H, N7H, N3H and N1H) of each of adenine and 2-aminopurine (2AP) were optimized using an ab initio approach employing a mixed basis set (6-311+G* on the nitrogen atom of the amino group and 4-31G basis set on the other atoms). Excited states were generated employing configuration interaction involving single electron excitations (CIS). Subsequently, the different species were solvated in water employing the self-consistent reaction field (SCRF) approach along with the corresponding gas phase optimized geometries. Thus the observed absorption and fluorescence spectra of adenine and 2AP have been explained successfully. It is concluded that both the N9H and N7H forms of 2AP would contribute to absorption and fluorescence spectra. Further, the fluorescence of 2AP would be absorbed by its cation in which both the N9 and N7 atoms are protonated, the fluorescence of which can have an anti-Stokes component. Among the different tautomers of adenine, the N9H form would be present dominantly in the ground state in aqueous solutions but the N7H form would be produced by energy transfer and subsequent fluorescence. The N3H form of adenine appears to be responsible for the observed absorption near 300 nm by its solutions intermittently exposed to ultraviolet radiation. The rings of the different species related to 2AP and adenine remain almost planar in the ?-?* and n-?* singlet excited states as in the ground state. The pyramidal character of the amino group is usually less in the ?-?* excited states than that in the corresponding ground or n-?* excited states. Molecular electrostatic potential (MEP) maps of the molecules provide useful clues regarding phototautomerism.

Mishra, S. K.; Shukla, M. K.; Mishra, P. C.

2000-06-01

206

On-Chip Transient Detection Circuit for System-Level ESD Protection in CMOS Integrated Circuits to Meet Electromagnetic Compatibility Regulation  

Microsoft Academic Search

A new on-chip transient detection circuit for system-level electrostatic discharge (ESD) protection is proposed. The circuit performance to detect different positive and negative fast electrical transients has been investigated by the HSPICE simulator and verified in a silicon chip. The experimental results in a 0.13-m CMOS integrated circuit (IC) have confirmed that the proposed on-chip transient detection circuit can be

Ming-Dou Ker; Cheng-Cheng Yen; Pi-Chia Shih

2008-01-01

207

Features of the NCth in SEE spectra  

NASA Astrophysics Data System (ADS)

Basing on experiments carried out at the Sura heating facility it has been elaborated an empirical model for generation of the thermal narrow continuum NC th in stimulated electromagnetic emission SEE spectra which is observed in the lower sideband of the pump wave PW frequency extending up to the down-shifted maximum DM and the spectral intensity of which decreases exponentially with the increase of frequency shift from the pump The generation of NC th as well as DM and broad continuum BC occurs due to excitation of the thermal resonance parametric instability TPI Integral intensity of the NC th is close to or even higher than DM integral intensity The basic characteristics of the NC th are very similar to analogous DM ones Among them are magnitudes of their thresholds strong influence of HF-induced striations on their features dependences of their intensity on PW frequency PW power and heating antenna beam position relatively to the geomagnetic field gyro features typical times of their development after PW switch-on generation of these SEE components when a PW frequency is slightly below of F 2 -region critical frequency f 0F2 but an upper hybrid resonance frequency for the PW still remains below f 0F2 The intensity of the NC th as for DM has a maximal level in a PW frequency range from 5 to 7 MHz and it is fast reduced outside of this range The form of NC th spectra is often very similar to the spectral form of DM and its satellites DM1 and DM2 for their low frequency flanks

Frolov, V. L.; Nedzvetski, D. I.; Sergeev, E. N.

208

Coherent population trapping in intersubband photocurrent spectra  

NASA Astrophysics Data System (ADS)

We present results from numerical simulations of the photocurrent generated by intersubband optical transitions in a double quantum well coupled with a continuum of extended states. The photocurrent spectra are obtained directly from the time-dependent Schrödinger equation for the coherent regime without any adjusting parameters in the calculations other than the ones that define the physical system, also in a nonperturbative way and without basis-set expansions or truncations. A realistic representation of a three-level system in the Lambda (“?”) configuration is investigated when two bound states in each quantum well are coupled by exciting fields via an excited quasibound state. Resonance between the exciting fields and the quantum states leads to coherent effects such as Rabi-dressed states, electromagnetically induced transparency, and population trapping, which are investigated in terms of the photocurrent spectral changes; that is, the coherent optical dynamics can be seen from the photocurrent signal. An excitation scheme involving two-photon absorption was proposed to produce the population-trapping effects using only one exciting field.

Maialle, Marcelo Z.; Degani, Marcos H.

2011-04-01

209

Cyclone Spectra  

NASA Astrophysics Data System (ADS)

As the resolution of climate models improves so will their ability to replicate the full spectrum of cyclones 'observed' in the atmosphere. This improved capability will need to be matched by improved techniques for locating and tracking cyclones in the model output. This presentation will advertise two such techniques, developed recently, and which have hitherto been used only on the output of shorter range oper- ational forecast models. As will be shown with examples, the techniques are particu- larly valuable at the extreme end of the range, where the most damaging cyclones are often small, fast-moving and relatively short-lived. Reference will also be made to a current North Atlantic climatology of low pres- sure centres and frontal waves, as diagnosed from a recently constructed 'cyclone database' put together using the above techniques. This database contains many at- tributes for each cylonic feature, including upper level jet diagnostics and a proxy for maximum surface gusts. Examples will be given of relationships derived from the database. Potentially these can also assist in the interpretation of climate model output, by providing an indirect means of inferring probabilities of extreme weather events.

Hewson, T. D.

210

Electromagnetic particle simulation codes  

Microsoft Academic Search

Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent\\u000a electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code\\u000a which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse\\u000a and longitudinal components. The transverse \\u000a $$\\\\underset{\\\\raise0.3em\\\\hbox{$\\\\smash{\\\\scriptscriptstyle\\\\thicksim}$}}{E} $$\\u000a and \\u000a $$\\\\underset{\\\\raise0.3em\\\\hbox{$\\\\smash{\\\\scriptscriptstyle\\\\thicksim}$}}{B}

P. L. Pritchett

1985-01-01

211

The ALICE Electromagnetic Calorimeters  

NASA Astrophysics Data System (ADS)

ALICE is the general purpose experiment at the LHC dedicated to the study of heavy ion collisions. ALICE includes two different electromagnetic calorimeters: a high resolution, modest acceptance PHoton Spectrometer (PHOS) and a large acceptance, moderate resolution electromagnetic calorimeter (EMCal). The electromagnetic calorimeters are designed to trigger on high energy gamma-rays and jets, and to enhance the capabilities of ALICE for these measurements. The PHOS is a PbWo4 crystal calorimeter while the EMCal is a Ph/Scintillator sampling shish-kebab type calorimeter. The PHOS and EMCal construction, readout, and performance are described.

Awes, Terry C.

2012-08-01

212

High frequency electromagnetic tomography  

SciTech Connect

An experiment was conducted in G Tunnel at the Nevada Test Site to evaluate high frequency electromagnetic tomography as a candidate for in situ monitoring of hydrology in the near field of a heater placed in densely welded tuff. Tomographs of 200 MHz electromagnetic permittivity were made for several planes between boreholes. Data were taken before the heater was turned on, during heating and during cooldown of the rockmass. This data is interpreted to yield maps of changes in water content of the rockmass as a function of time. This interpretation is based on laboratory measurement of electromagnetic permittivity as a function of water content for densely welded tuff. 8 refs., 6 figs.

Daily, W.; Ramirez, A.; Ueng, T.; Latorre, R.

1989-09-01

213

Electromagnetic fluctuations and normal modes of a drifting relativistic plasma  

SciTech Connect

We present an exact calculation of the power spectrum of the electromagnetic fluctuations in a relativistic equilibrium plasma described by Maxwell-Jüttner distribution functions. We consider the cases of wave vectors parallel or normal to the plasma mean velocity. The relative contributions of the subluminal and supraluminal fluctuations are evaluated. Analytical expressions of the spatial fluctuation spectra are derived in each case. These theoretical results are compared to particle-in-cell simulations, showing a good reproduction of the subluminal fluctuation spectra.

Ruyer, C.; Gremillet, L.; Bénisti, D. [CEA, DAM, DIF, F-91297 Arpajon (France)] [CEA, DAM, DIF, F-91297 Arpajon (France); Bonnaud, G. [CEA, Saclay, INSTN, F-91191 Gif-sur-Yvette (France)] [CEA, Saclay, INSTN, F-91191 Gif-sur-Yvette (France)

2013-11-15

214

Electromagnetic fluctuations and normal modes of a drifting relativistic plasma  

NASA Astrophysics Data System (ADS)

We present an exact calculation of the power spectrum of the electromagnetic fluctuations in a relativistic equilibrium plasma described by Maxwell-Jüttner distribution functions. We consider the cases of wave vectors parallel or normal to the plasma mean velocity. The relative contributions of the subluminal and supraluminal fluctuations are evaluated. Analytical expressions of the spatial fluctuation spectra are derived in each case. These theoretical results are compared to particle-in-cell simulations, showing a good reproduction of the subluminal fluctuation spectra.

Ruyer, C.; Gremillet, L.; Bénisti, D.; Bonnaud, G.

2013-11-01

215

Experimental investigation of the hyperfine spectra of Pr I-lines: Discovery of new fine structure levels with high angular momentum  

NASA Astrophysics Data System (ADS)

We present 66 even and 58 odd parity newly discovered fine structure levels of Pr I with high angular momentum: J = 15/2, 17/2 and 19/2 and 21/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. More than 800 spectral lines could be classified with help of these levels. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2014-50025-7

Siddiqui, Imran; Khan, Shamim; Windholz, Laurentius

2014-05-01

216

Electromagnetically Driven Flux Compression.  

National Technical Information Service (NTIS)

Electromagnetically driven flux compression (EMC) devices are developed with a view to applications for experiments with megagauss fields, in particular for a study of magnetic bremsstrahlung. Fields of the order of 1.3 MG are reproducibly generated by me...

D. Kachilla, F. Herlach, T. Erber

1969-01-01

217

Electromagnetic Field Probes.  

National Technical Information Service (NTIS)

The report summarizes activities during the first quarter of a program directed to the development of probes and techniques for measurement of electromagnetic radiation in shielded enclosures over the 20 to 200 MHz frequency range. Studies were made of te...

G. W. Bechtold J. L. Birchfield R. D. Wetherington

1972-01-01

218

Electromagnetic structure of nuclei  

NASA Astrophysics Data System (ADS)

A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei for which significant progress was obtained in the two years since the last meeting in this series at Steamboat Springs Colorado.

Arnold, R. G.

1986-10-01

219

Electromagnetic structure of nuclei  

SciTech Connect

A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei for which significant progress was obtained in the two years since the last meeting in this series at Steamboat Springs Colorado.

Arnold, R.G.

1986-10-15

220

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This interactive, online module reviews the basics of the the electromagnetic spectrum and makes the connection between radiation theory and the images we get from weather satellites. Students will learn about: the electromagnetic spectrum; electromagnetic waves; the electromagnetic spectrum and radiation theory; and how satellite radiometers "see" different sections of the spectrum. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

221

Electromagnetism in the Movies.  

ERIC Educational Resources Information Center

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)

Everitt, Lori R.; Patterson, Evelyn T.

1999-01-01

222

Research in Electromagnetic Scattering.  

National Technical Information Service (NTIS)

In the main area of Frequency-Domain Electromagnetics, we made significant accomplishments in the sub-areas of Scattering-Matrix Analysis of periodic Arrays, Bandwidth and Quality Factor of Antennas, Supergain Arrays, and Surface Integral Equations. Yaghj...

A. Yaghjian

2006-01-01

223

Electromagnetically Induced Transparency.  

National Technical Information Service (NTIS)

We report the first observation of electromagnetically induced transparency in optically thick medium. The transparency results from a destructive interference of two dressed states which are created by applying a temporally smooth coupling laser between ...

A. Imamoglu K. J. Boiler S. E. Harris

1992-01-01

224

A Compact Electromagnetic Accelerator.  

National Technical Information Service (NTIS)

An electromagnetic pellet accelerator for the injection of glass beads into a plasma accelerator is used to simulate cometary dust for collection method development. The accelerator is described and a schematic diagram given. Its operational characteristi...

E. Igenbergs H. Kuczera P. Lell

1980-01-01

225

Solar Nantenna Electromagnetic Collectors.  

National Technical Information Service (NTIS)

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...

D. Slafe D. K. Kotter P. Pinhero S. D. Novack

2008-01-01

226

An opening electromagnetic transducer  

NASA Astrophysics Data System (ADS)

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.

Sun, Yanhua; Kang, Yihua

2013-12-01

227

Electromagnetism from counting.  

National Technical Information Service (NTIS)

The fact that experimental accuracy is finite makes the measurement of particle positions and velocities non-local and often non- commutative even in a scale invariant theory. Applied to electromagnetic and gravitational phenomena, we argue that this lead...

H. P. Noyes

1992-01-01

228

Electromagnetic rotational actuation.  

SciTech Connect

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.

Hogan, Alexander Lee

2010-08-01

229

ADAPTING GID FOR ELECTROMAGNETICS  

Microsoft Academic Search

The objective of this paper is to show and share the experiences on the use of GiD as a pre- and post- processor for some of the electromagnetic FEM codes developed in the Research Group that the authors belong to. GiD has advantageous features but important limitations for electromagnetic problems, mainly due to the unavailability of non-standard (H(curl) and H(div)

Diego Sánchez-Repila; Luis E. García-Castillo

230

Inhomogeneous electromagnetic gravitational collapse  

SciTech Connect

The collapse of an inhomogeneous dust cloud in the presence of an electromagnetic field is investigated in detail. The possibility of a naked singularity arising is studied using some known solutions for a spherical charged inhomogeneous dust cloud. It is found that locally naked singularities may develop when the arbitrary functions in the solution are chosen in a special way, but that a global naked singularity will not form. Also the role of the electromagnetic pressure is discussed.

Stein-Schabes, J.A.

1985-04-15

231

Electromagnetic navigation guided bronchoscopy  

PubMed Central

Abstract This review describes the technique and applications of an emerging bronchoscopic approach utilizing three-dimensional reconstructions of chest computed tomography scans to facilitate electromagnetic guidance to peripheral lung nodules. This approach, electromagnetic navigation bronchoscopy, is useful for biopsy, placement of fiducial markers, or dye marking of overlying pleura prior to thoracoscopic wedge resection. This technique offers some potential advantages over other forms of biopsy. The design, application, relative advantages and pitfalls of this system are the subject of this review.

2009-01-01

232

Electromagnetic properties for arbitrary spin particles: Natural electromagnetic moments from light-cone arguments  

SciTech Connect

We revisit the old-standing problem of the electromagnetic interaction for particles of arbitrary spin. Based on the assumption that light-cone helicity at tree level and Q{sup 2}=0 should be conserved nontrivially by the electromagnetic interaction, we are able to derive all the natural electromagnetic moments for a pointlike particle of any spin. We provide here a transparent decomposition of the electromagnetic current in terms of covariant vertex functions. We also define in a general way the electromagnetic multipole form factors, and show their relation with the electromagnetic moments and covariant vertex functions. The light-cone helicity conservation argument determines uniquely the values of all electromagnetic moments, which we refer to as the 'natural' ones. These specific values are in accordance with the standard model, and the prediction of universal g=2 gyromagnetic factor is naturally recovered. We provide a very simple and compact formula for these natural moments. As an application of our results, we generalize the discussion of quark transverse charge densities to particles with arbitrary spin, giving more physical support to the light-cone helicity conservation argument.

Lorce, Cedric [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany)

2009-06-01

233

Nuclear electromagnetic pulse penetration analysis in combat vehicle  

Microsoft Academic Search

The narrow width, large amplitude and fast rise time electromagnetic transient effect is of great concern to electronic systems. In this paper various coupling mechanisms of such an electromagnetic transient field in a combat vehicle platform are discussed. Efforts are made to mathematically model some of the coupling processes, predict and analyse the possible interaction levels inside the vehicle and

G. K. Deb

2000-01-01

234

Evidence for three surface components in the 3d core-level photoemission spectra of Ge(100)-(2×1) surface  

Microsoft Academic Search

The 3d surface core-level shifts of the clean Ge(100)(2×1) surface have been investigated at 300 K by photoemission. A previously unobserved (to our knowledge) shifted component at about +0.19 eV relative to the bulk emission has been clearly identified and associated with dimer down-atom emission. The binding energy difference of 0.72 eV between dimer down-atom and dimer up-atom 3d core

A. Goldoni; S. Modesti; V. R. Dhanak; M. Sancrotti; A. Santoni

1996-01-01

235

Theoretical energy level spectra and transition data for 4p64d2, 4p64d4f, and 4p54d3 configurations of W36+  

NASA Astrophysics Data System (ADS)

The ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive transition data for a multicharged tungsten ion. The configuration interaction method is applied to include electron correlation effects. The relativistic effects are taken into account in the Breit-Pauli approximation for quasirelativistic Hartree-Fock radial orbitals. The energy level spectra, radiative lifetimes and Lande g-factors are calculated for the 4p64d2, 4p64d4f, and 4p54d3 configurations of the ion W36+. The transition wavelengths, spontaneous transition probabilities, oscillator strengths, and line strengths for the electric dipole, electric quadrupole, electric octupole, and magnetic dipole transitions among the levels of these configurations are tabulated.

Bogdanovich, P.; Kisielius, R.

2013-09-01

236

Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

237

Questions of energy transformation in dc electromagnetic mechanisms. [Electromagnetic energy to energy of mechanical vibrations  

SciTech Connect

Electromagnetic reciprocal-motion transducers (EMT) are being used ever more extensively in modern industry. In particular, rubble to break down bulkiness, slicer drives for coal combines, drilling equipment, etc. are produced on the basis of EMT. This paper is devoted to further refinement of energy conversion questions and their analysis. The energy coming from the supply source in the magnetization of the additionally sucked-in armature volume is determined by the magnetic energy density in the armature section at the pole level. A general expression is deduced for the electromagnetic force of the EMT that sets up the interrelation between the whole system magnetic energy and the coil flux-linkage. It is shown that expressions known earlier for the electromagnetic forces, obtained for the constant current electromagnet and the constant flux-linkage cases, are particular cases of the general expression that is valid without any additional constraints for the condition of the EMT working process.

Simonov, B.F.

1986-05-01

238

IUPAC critical evaluation of the rotational-vibrational spectra of water vapor. Part IV. Energy levels and transition wavenumbers for D216O, D217O, and D218O  

NASA Astrophysics Data System (ADS)

This paper is the fourth of a series of papers reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This paper presents energy level and transition data for the following doubly and triply substituted isotopologues of water: D216O, D217O, and D218O. The MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0-14 016, 0-7969, and 0-9108 cm-1 for D216O, D217O, and D218O, respectively. For D216O, D217O, and D218O, 53 534, 600, and 12 167 lines are considered, respectively, from spectra recorded in absorption at room temperature and in emission at elevated temperatures. The number of validated energy levels is 12 269, 338, and 3351 for D216O, D217O, and D218O, respectively. The energy levels have been checked against the ones determined, with an average accuracy of about 0.03 cm-1, from variational rovibrational computations employing exact kinetic energy operators and an accurate potential energy surface. Furthermore, the rovibrational labels of the energy levels have been validated by an analysis of the computed wavefunctions using the rigid-rotor decomposition (RRD) scheme. The extensive list of MARVEL lines and levels obtained is deposited in the Supplementary Material of this paper, in a distributed information system applied to water, W@DIS, and on the official MARVEL website, where they can easily be retrieved.

Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Dénes, Nóra; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Hu, Shui-Ming; Szidarovszky, Tamás; Vasilenko, Irina A.

2014-07-01

239

Electromagnetic modeling of plasmonic nanostructures  

NASA Astrophysics Data System (ADS)

In this thesis, plasmonic properties of metal nanostructures are investigated by electromagnetic simulations using the finite difference time domain (FDTD) method. Chapter 1 covers the background knowledge required to read this thesis. It talks about the fundamentals of the FDTD method, the physics of plasmonics and a brief description of photocatalysis. In chapter 2, we perform optimization of plasmonic nanoparticle geometries. An iterative optimization algorithm is used to determine the configuration of the nanoparticles that gives the maximum electric field intensity at the center of the cluster. We observe that the optimum configurations of these clusters have mirror symmetry about the axis of planewave propagation, but are otherwise non-symmetric and non-intuitive. The maximum field intensity is found to increase monotonically with the number nanoparticles in the cluster, producing intensities that are 2500 times larger than the incident electromagnetic field. In chapter 3, evaporated thin films are imaged with high resolution transmission electron microscopy (HRTEM), to reveal the structure of the semicontinuous metal island film with sub-nm resolution. The electric field distributions and the absorption spectra of these semicontinuous island film geometries are calculated using the finite difference time domain (FDTD) method and compared with the experimentally measured absorption spectra. In addition to that, we calculate the SERS enhancement factors and photocatalytic enhancement factors of these films. We also study the effect of annealing on these films, which results in a large reduction in electric field strength due to increased nanoparticle spacing. In chapter 4, we study the effects of surrounding nanoparticles on a plasmonic hot spot. From our simulations, we show that the surrounding film contributes significantly to the electric field intensity at the hot spot by focusing energy to it. Widening of the gap size causes a decrease in the intensity at the hot spot. However, these island-like nanoparticle hot spots are shown to be robust to gap size than nanoparticle dimer geometries, studied previously. In fact, the main factor in determining the hot spot intensity is the focusing effect of the surrounding nano-islands. In chapter 5, we demonstrate plasmon-enhanced photocatalytic water splitting, and reduction of CO2 with H2O to form hydrocarbon fuels. Under visible illumination, we observe enhancements of up to 66X in the photocatalytic splitting of water in TiO2 with the addition of Au nanoparticles. We also perform a systematic study of the mechanisms of Au nanoparticle/TiO 2-catalyzed photoreduction of CO2 and water vapor over a wide range of wavelengths. In this case, under visible light illumination, we observe a 24-fold enhancement in the photocatalytic activity due to the intense local electromagnetic fields created by the surface plasmons of the Au nanoparticles. Above the plasmon resonance, under ultraviolet radiation we observe a reduction in the photocatalytic activity. Electromagnetic simulations indicate that the improvement of photocatalytic activity in the visible range is caused by the local electric field enhancement near the TiO2 surface, rather than by the direct transfer of charge between the two materials. In chapter 6, I will talk about a method for fabricating arrays of plasmonic nanoparticles with separations on the order of 1nm using an angle evaporation technique. High resolution transmission electron microscopy (HRTEM) is used to resolve the small separations achieved between nanoparticles fabricated on thin SiN membranes. These nearly touching metal nanoparticles produce extremely high electric field intensities when irradiated with laser light. We perform surface enhanced Raman spectroscopy (SERS) a non-resonant dye molecule (p-ATP) deposited on the nanoparticle arrays using confocal micro-Raman spectroscopy. Our results show significant enhancement when the incident laser is polarized parallel to the axis of the nanoparticle pairs, whereas no enhancement is observed for the p

Pavaskar, Prathamesh

240

Electromagnetic attachment mechanism  

NASA Technical Reports Server (NTRS)

An electromagnetic attachment mechanism is disclosed for use as an end effector of a remote manipulator system. A pair of electromagnets, each with a U-shaped magnetic core with a pull-in coil and two holding coils, are mounted by a spring suspension system on a base plate of the mechanism housing with end pole pieces adapted to move through openings in the base plate when the attractive force of the electromagnets is exerted on a strike plate of a grapple fixture affixed to a target object. The pole pieces are spaced by an air gap from the strike plate when the mechanism first contacts the grapple fixture. An individual control circuit and power source is provided for the pull-in coil and one holding coil of each electromagnet. A back-up control circuit connected to the two power sources and a third power source is provided for the remaining holding coils. When energized, the pull-in coils overcome the suspension system and air gap and are automatically de-energized when the pole pieces move to grapple and impose a preload force across the grapple interface. A battery backup is a redundant power source for each electromagnet in each individual control circuit and is automatically connected upon failure of the primary source. A centerline mounted camera and video monitor are used in cooperation with a target pattern on the reflective surface of the strike plate to effect targeting and alignment.

Monford, Leo G., Jr. (inventor)

1992-01-01

241

Radiated fields from an electromagnetic pulse simulator  

Microsoft Academic Search

Simulators of electromagnetic pulses allow generation within a limited time of very high-intensity fields such as those produced in a nuclear explosion. These fields can be radiated out of the test zone at a lower but nevertheless significant level; if the intensity of these fields is sufficiently high, damage to humans and electronic equipment can result. An evaluation of the

M. Pelletier; G. Y. Delisle; S. Kashyap

1990-01-01

242

Charging Ahead: An Introduction to Electromagnetism.  

ERIC Educational Resources Information Center

This guide explores the connection between electricity and magnetism with middle level and high school students. The phenomenon of electromagnetism is broken down into four lesson plans that provide students and teachers with a carefully constructed yet easy way to learn about their history. All four activities prompt students to use inexpensive,…

Shafer, Larry E.

243

Neutron irradiation effects on electrical properties and deep-level spectra in undoped n-AlGaN/GaN heterostructures  

SciTech Connect

The effect of neutron irradiation on the electrical properties of undoped n-AlGaN/GaN heterostructures is reported. The two-dimensional electron-gas (2DEG) mobility starts to decrease at neutron doses above 10{sup 14} cm{sup -2}, while the 2DEG concentration slightly increases at low doses and decreases dramatically for doses higher than 2.5x10{sup 16} cm{sup -2}. The result is that the mobility/concentration product (a figure of merit for transistors) starts to decrease appreciably after the dose of 10{sup 15} cm{sup -2}. Capacitance-voltage and admittance spectroscopies, indicate that tunneling of electrons into the states near E{sub c}-0.21 eV in AlGaN is a serious factor when cooling down the virgin or lightly irradiated samples. For heavily irradiated samples the states in AlGaN are close to 0.3 and 0.45 eV, respectively, from the bottom of the conduction band. Deep-level spectroscopy measurements reveal the presence of hole traps with apparent activation energies of 0.18 and 0.21 eV for lightly irradiated samples and deeper hole traps with activation energies of 0.6 and 1 eV in heavily irradiated samples.

Polyakov, A.Y.; Smirnov, N.B.; Govorkov, A.V.; Markov, A.V.; Pearton, S.J.; Kolin, N.G.; Merkurisov, D.I.; Boiko, V.M. [Institute of Rare Metals, B. Tolmachevsky 5, Moscow 119017 (Russian Federation); Department of Materials Science and Engineering, University of Florida, 132 Rhines Hall, Gainesville, Florida 32611 (United States); Obninsk Branch of Federal State Unitary Enterprise, Karpov Institute of Physical Chemistry, 249033 Obninsk, Kaluga region, Kiev Avenue (Russian Federation)

2005-08-01

244

Electromagnetic particle simulation codes  

NASA Technical Reports Server (NTRS)

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.

Pritchett, P. L.

1985-01-01

245

Aircraft electromagnetic compatibility  

NASA Technical Reports Server (NTRS)

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.

Clarke, Clifton A.; Larsen, William E.

1987-01-01

246

Metamaterial electromagnetic wave absorbers.  

PubMed

The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. PMID:22627995

Watts, Claire M; Liu, Xianliang; Padilla, Willie J

2012-06-19

247

Estimation of sea level muon energy spectra in the energy range 0.2 GeV TO 10 GeV  

NASA Astrophysics Data System (ADS)

The vertical muon energy spectrum has been calculated in the energy range 0.2 GeV to 10 GeV using the latest directly measured primary cosmic ray nucleon spectrum . The primary cosmic ray nucleon spectrum has been calculated from the available measurements JACEE, CRN, SOKOL and the experiments done by Ramaty, Ryan, Seo, Badhwar on P, He, CNO, Ne -Si and Fe. Then using the superposition model the all nucleon spectrum has been constructed which makes the form N(E)dE = 1.13E-2.61 dE [cm2 .s.sr.GeV/n]-1 The pT integrated Lorentz invariant crosssections available from the CERN LEBC EHS data for ?± and K± production initiated by pp collisions has been fitted and then from the fitting parameters hadronic energy moments have been calculated. The adopted inelastic crosssection for pp interactions is 35 mb and the value of ?p-air cross-section has been adopted as 273 mb.The Z-factors have been corrected for p-air collisions using the methodology of Minorikawa and Mitsui. The Q-G plasma correction of Z-factors has also been made. Adopting the methodology of Arnon Dar and taking the other interaction parameters the modified production co-efficients gNM AT M have been calculated. To calculate the muon flux in this methode one has to estimate C? and CK for which we used the parametric values like B? = 1, BK = 0.632, pa = 2.3424, ?K = 1.048.Using those values, C? and CK have been found out to be 0.220137 and 0.007149 respectively. The survival probability of muons which are produced at atmospheric depth ?0 to survive down to atmospheric depth l has been calculated with the help of the average muon production depth ?0 = 100 gm-cm-2 and survival depth ?F = 1033 gmcm-2 , respectively. The energy loss of muon during its propagation through atmosphere has been calculated. Finally the vertical muon energy spectrum at sea level from conventinal meson decay has been estimated and compared with experimental data of CAPRICE-94 (1999), Allkofer et al.(1976), Allkofer et al. (1971) and Hayman and Wolfendale (1962). It is found that estimated vertical muon energy spectrum in the low energy range is well in agreement with the experimental results. The results of Caprice-94 are lying below our results may be due to the strong solar activity that causes a depression in the muon intensity near 1 GeV region.

Haldar, T. K.; Mitra, M.; Bhattacharyya, D. P.

248

Electromagnetically induced absorption via incoherent collisions  

SciTech Connect

We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

Yang Xihua [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Department of Physics, Shanghai University, Shanghai 200444 (China); Sheng Jiteng; Xiao Min [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2011-10-15

249

Improved Electromagnetic Brake  

NASA Technical Reports Server (NTRS)

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 still be possible to set the brake by applying an electromagnet current to aid the permanent magnetic field instead of canceling it, this action can mask an out-of-tolerance condition in the brake and it does not restore the fail-safe function of setting the brake when current is lost.

Martin, Toby B.

2004-01-01

250

Mixed-level optical-system simulation incorporating component-level modeling of interface elements  

NASA Astrophysics Data System (ADS)

While system-level simulation can allow designers to assess optical system performance via measures such as signal waveforms, spectra, eye diagrams, and BER calculations, component-level modeling can provide a more accurate description of coupling into and out of individual devices, as well as their detailed signal propagation characteristics. In particular, the system-level simulation of interface components used in optical systems, including splitters, combiners, grating couplers, waveguides, spot-size converters, and lens assemblies, can benefit from more detailed component-level modeling. Depending upon the nature of the device and the scale of the problem, simulation of optical transmission through these components can be carried out using either electromagnetic device-level simulation, such as the beampropagation method, or ray-based approaches. In either case, system-level simulation can interface to such componentlevel modeling via a suitable exchange of optical signal data. This paper presents the use of a mixed-level simulation flow in which both electromagnetic device-level and ray-based tools are integrated with a system-level simulation environment in order to model the use of various interface components in optical systems for a range of purposes, including, for example, coupling to and from optical transmission media such as single- and multimode optical fiber. This approach enables case studies on the impact of physical and geometric component variations on system performance, and the sensitivity of system behavior to misalignment between components.

Mena, Pablo V.; Stone, Bryan; Heller, Evan; Herrmann, Dan; Ghillino, Enrico; Scarmozzino, Rob

2014-03-01

251

Crystal-field analysis for RE 3+ ions in laser materials: I. Absorption spectra and energy levels calculations for Nd 3+ and Pr 3+ ions in ABCO 4 crystals  

NASA Astrophysics Data System (ADS)

Low temperature polarized absorption spectra are analyzed to achieve assignments of energy levels for Nd 3+ ions at tetragonal C 4v symmetry sites in SrLaAlO 4:Nd 3+, SrLaGaO 4:Nd 3+, and CaNdAlO 4 as well as Pr 3+ ions at C 4v sites in SrLaAlO 4:Pr 3+ crystals. The C 4v selection rules for polarized electric dipole transitions are strictly obeyed for Pr 3+ ion doped into SrLaAlO 4. However, for Nd 3+ ions in the same crystal neither the C 4v polarization rules nor the C 4 ones are strictly confirmed. This is explained in terms of structural disorder. The experimental energy levels for Pr 3+ and Nd 3+ ions in these crystals were analyzed in terms of the free-ion parameters and the crystal field (CF) ones, B kq, assuming C 4v site symmetry and using the starting values of B kq's obtained from superposition model (SPM) analysis. A good agreement between the calculated and experimental energy levels was obtained with rms deviations in the range from 20.5 to 23.6 cm -1 for Nd 3+-doped crystals and 19.8 cm -1 for SrLaAlO 4:Pr 3+. Using the CF parameters B kq optimized in fittings of the calculated and experimental energy levels, the model parameters, i.e. the intrinsic parameters B and the power law exponents t k, were determined and compared with those for other similar systems hitherto studied. The obtained values of the intrinsic parameters may serve as a starting point for SPM analysis of CF parameters for other systems, particularly those exhibiting low symmetry of metal centers. As an example of such systems, we consider Nd 3+ ions at triclinic C 1 symmetry sites in BaLaAlO 4:Nd 3+ crystals. Low temperature polarized absorption spectra for this system is also analyzed yielding assignments of energy levels. The results of preliminary low symmetry CF analysis carried out for BaLaAlO 4:Nd 3+ are presented.

Karbowiak, M.; Rudowicz, C.

2011-05-01

252

Review of Quantum Electromagnetic States.  

National Technical Information Service (NTIS)

This program provided a review of the conceptual and mathematical apparatus to apply modern theories of electromagnetic fields. As a study in low- noise electromagnetic states, it centers on the need to transition basic physics into the engineering arena ...

M. A. Parker

1999-01-01

253

Canceling Electromagnetic Interference During Tests  

NASA Technical Reports Server (NTRS)

Old technique solves modern problem. Simple amplitude-and-phase-cancellation technique removes strong electromagnetic interference from received test signal, enabling recovery of relatively weak signal from device under test. Useful in outdoor tests of devices for electromagnetic compatibility.

Robinson, Paul A., Jr.; Edmonds, Larry D.

1988-01-01

254

New Perspective on Classical Electromagnetism.  

National Technical Information Service (NTIS)

The fallacies associated with the gauge concept in electromagnetism are illustrated. A clearer and more valid formulation of the basics of classical electromagnetism is provided by recognizing a previously overlooked law of induction as well as the physic...

M. Johnson P. Cote

2013-01-01

255

Night Spectra Quest.  

ERIC Educational Resources Information Center

Presents the Night Spectra Quest, a pocket-sized chart that identifies in color the spectra of all the common night lights and has an integrally mounted, holographic diffraction grating to look through. (JRH)

Jacobs, Stephen

1995-01-01

256

Electromagnetic simulation environment  

Microsoft Academic Search

We present a general purpose simulator that includes electromagnetic scattering tools for buried targets and standard signal processing functionality. Additional modules for genetic or gradient optimization, parallel processing, and multi-aspect target detection via Hidden Markov Models are also available. The entire library is completely scriptable for customization and web enabled for publishing results on the internet. It is also extensible

Eric Jones; Balaji Krishnapuram; John Pormann; John A. Board; Lawrence Carin

2001-01-01

257

Electro-Magnetic Actuator.  

National Technical Information Service (NTIS)

The electro-magnetic wave generator is particularly adapted for creating a rotating wave in the flexible ring gear of a harmonic drive device. One application of the harmonic drive as a speed reducer is in propelling small, deep diving research submarines...

C. F. Janes

1965-01-01

258

Computation of Electromagnetic Fields  

Microsoft Academic Search

This paper reviews some of the more useful, current and newly developing methods for the solution of electromagnetic fields. It begins with an introduction to numerical methods in general, including specific references to the mathematical tools required for field analysis, e.g., solution of systems of simultaneous linear equations by direct and iterative means, the matrix eigenvalue problem, finite difference differentiation

A. Wexler

1969-01-01

259

Equivalence principles and electromagnetism  

NASA Technical Reports Server (NTRS)

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.

Ni, W.-T.

1977-01-01

260

Electromagnetic brain mapping  

Microsoft Academic Search

There has been tremendous advances in our ability to produce images of human brain function. Applications of functional brain imaging extend from improving our understanding of the basic mechanisms of cognitive processes to better characterization of pathologies that impair normal function. Magnetoencephalography (MEG) and electroencephalography (EEG) (MEG\\/EEG) localize neural electrical activity using noninvasive measurements of external electromagnetic signals. Among the

S. Baillet; J. C. Mosher; R. M. Leahy

2001-01-01

261

Nuclear Electromagnetic Pulse Review  

Microsoft Academic Search

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

Michael Dinallo

2011-01-01

262

Adaptive electromagnetic shunt damping  

Microsoft Academic Search

This paper presents a new type of passive vibration control: adaptive electromagnetic shunt damping. We propose a single-mode resonant shunt controller that adapts to environmental conditions using two different adaptation strategies. The first technique is based on minimizing the root mean square (RMS) vibration, while the second minimizes the phase difference between two measurable signals. An experimental comparison shows that

Dominik Niederberger; Sam Behrens; Andrew J. Fleming; S. O. R. Moheimani; Manfred Morari

2006-01-01

263

Focusing of electromagnetic waves.  

National Technical Information Service (NTIS)

The focusing of electromagnetic waves inside a slab has been examined together with two special cases in which the slab is reduced to a single interface or a single medium. To that end the exact solutions for the fields inside a layered medium have been u...

V. Dhayalan

1996-01-01

264

Simple Superconducting "Permanent" Electromagnet  

NASA Technical Reports Server (NTRS)

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.

Israelson, Ulf E.; Strayer, Donald M.

1992-01-01

265

Physics 2000: Electromagnetic Waves  

NSDL National Science Digital Library

This website presents the physics of electromagnetic waves by describing the properties of waves, electric forces, force fields, and vibrating charges. Interactive animations and a question and answer "tutorial" format is used to present the information. Presentations about the applications of E&M waves are also included.

Goldman, Martin

2004-07-14

266

What are Electromagnetic Metamaterials?  

NSDL National Science Digital Library

Metamaterials are artificial structures that display properties beyond those available in naturally occuring materials. Materials interact with light and other electromagnetic fields. Because of this, materials can be used to control light in various ways, forming the basis for optical devices. This website from Duke University gives more details and graphs.

2011-08-29

267

SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS  

Microsoft Academic Search

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

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

2008-01-01

268

Analytical model for electromagnetic cascades in rotating electric field  

SciTech Connect

Electromagnetic cascades attract a lot of attention as an important quantum electrodynamics effect that will reveal itself in various electromagnetic field configurations at ultrahigh intensities. We study cascade dynamics in rotating electric field analytically and numerically. The kinetic equations for the electron-positron plasma and gamma-quanta are formulated. The scaling laws are derived and analyzed. For the cascades arising far above the threshold the dependence of the cascade parameters on the field frequency is derived. The spectra of high-energy cascade particles are calculated. The analytical results are verified by numerical simulations.

Nerush, E. N.; Bashmakov, V. F.; Kostyukov, I. Yu. [Institute of Applied Physics, Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation)

2011-08-15

269

Attosecond electromagnetic pulse generation due to the interaction of a relativistic soliton with a breaking-wake plasma wave.  

PubMed

During the interaction of a low-frequency relativistic soliton with the electron density modulations of a wake plasma wave, part of the electromagnetic energy of the soliton is reflected in the form of an extremely short and ultraintense electromagnetic pulse. We calculate the spectra of the reflected and of the transmitted electromagnetic pulses analytically. The reflected wave has the form of a single cycle attosecond pulse. PMID:15903585

Isanin, A V; Bulanov, S S; Kamenets, F F; Pegoraro, F

2005-03-01

270

Computational Electronics and Electromagnetics  

SciTech Connect

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.

DeFord, J.F.

1993-03-01

271

How Astronomers Use Spectra to Learn About the Sun and Other Stars  

NSDL National Science Digital Library

This is a booklet about spectra and their usefulness to astronomers. Learners will read about the electromagnetic spectrum, how atomic physics is used to obtain information out of stellar spectra, and how the Doppler effect is used to measure stellar motions. An activity at the end allows learners to analyze and identify several emission lines in the spectrum of the Sun.

272

Electromagnetic effects in crustal fracturing  

NASA Astrophysics Data System (ADS)

The major results from field observation of electromagnetic precursors of seismic events are presented. These phenomena, including disturbances in the atmospheric electric potential, pulsed electromagnetic radiation, electrotelluric fields and luminous effects, characteristically appear on the order of the hours to days before earthquakes, with earthquakes occurring during a decrease in the phenomena. The phenomena occur over a broad frequency range. All anomalies except for electromagnetic radiation have been observed at the epicenters of earthquakes. Foreshocks have not been recorded during these anomalies. No burst of electromagnetic, atmospheric electric or electrotelluric fields has been observed at the moment of earthquakes. Electromagnetic radiation in the radio frequency band is considered most promising for earthquake prediction purposes. The specific characteristics of electromagnetic radiation caused by seismic phenomena must be determined in order to distinguish this radiation from other electromagnetic radiation.

Gokhberg, M. B.; Gufeld, I. L.; Gershenzon, N. I.; Pilipenko, V. A.

1985-08-01

273

Electromagnetic targeting of guns  

SciTech Connect

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.

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

1996-10-01

274

Magnetism and Electromagnetism  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Magnetism and Electromagnetism, is the fourteenth chapter in Volume I â Direct Current. A few of the topics covered in this chapter include: Permanent magnets; Electromagnetic induction; and Mutual inductance. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-07

275

Electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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.

Bailey, R. L. (inventor)

1973-01-01

276

Broadband cavity electromagnetically induced transparency  

SciTech Connect

Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

Wei Xiaogang [Department of Physics, Florida International University, Miami, Florida 33199 (United States); College of Physics, Jilin University, Changchun 130023 (China); Wang Yanhua [Department of Physics, Florida International University, Miami, Florida 33199 (United States); College of Physics and Electronics, Shanxi University, Taiyuan 030006 (China); Zhang Jiepeng [Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Physics Division P-23, Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Zhu Yifu [Department of Physics, Florida International University, Miami, Florida 33199 (United States)

2011-10-15

277

Avalanche photodiodes for electromagnetic calorimeters  

NASA Astrophysics Data System (ADS)

Hamamatsu S8148 silicon avalanche photodiode (APD) working in proportional mode has been chosen as readout device for the PbWO 4 crystals in the barrel of the CMS electromagnetic calorimeter (ECAL). High hadron fluences strongly affect the main parameters of both the scintillation crystals and the silicon detectors. In this work, we offer a new zinc sulfide-silicon (ZnS-Si) isotype heterojunction APD structure that is able to operate in high-radiation levels. A Monte Carlo simulation code has been performed in order to compare the Hamamatsu S8148 and the ZnS-Si APD structures for the photons emitting from PbWO 4 crystal during 10 years of CMS operation. Based on this work, the performance of these two APD structures has been investigated.

Pilicer, Ercan; Kocak, Fatma; Tapan, Ilhan; Ahmetoglu (Afrailov), Muhitdin

2007-03-01

278

Ordinary electromagnetic mode instability  

NASA Technical Reports Server (NTRS)

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.

Cheng, C. Z.

1974-01-01

279

Electromagnetic Hammer for Metalworking  

NASA Technical Reports Server (NTRS)

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.

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

280

Electromagnetic Interference Reduction Filters  

Microsoft Academic Search

This paper presents the theory and application of lumped-image parameter reactive filter networks, absorptive-type filter networks, and combined absorptive-reactive filter networks as conducted electromagnetic interference reduction circuits. A comparison of the passband characteristics by specific examples is given for filter configurations of the pi, T, absorptive, and absorptive-reactive type under implementation conditions of a fixed source impedance and a varying

Henry Hoffart

1968-01-01

281

The KLOE electromagnetic calorimeter  

Microsoft Academic Search

The KLOE calorimeter is a fine lead-scintillating fiber sampling calorimeter. We describe in the following the calibration procedures and the calorimeter performances obtained after 3 years of data taking. We get an energy resolution for electromagnetic showers of 5.4%\\/E(GeV) and a time resolution of 56 ps\\/E(GeV). We also present a measurement of efficiency for low-energy photons.

M. Adinolfi; F. Ambrosino; A. Antonelli; M. Antonelli; F. Anulli; G. Barbiellini; G. Bencivenni; S. Bertolucci; C. Bini; C. Bloise; V. Bocci; F. Bossi; P. Branchini; G. Cabibbo; R. Caloi; P. Campana; M. Casarsa; G. Cataldi; F. Ceradini; F. Cervelli; P. Ciambrone; E. De Lucia; P. De Simone; G. De Zorzi; S. Dell'Agnello; A. Denig; A. di Domenico; C. di Donato; S. Di Falco; A. Doria; O. Erriquez; A. Farilla; A. Ferrari; M. L. Ferrer; G. Finocchiaro; C. Forti; A. Franceschi; P. Franzini; M. L. Gao; C. Gatti; P. Gauzzi; A. Giannasi; S. Giovannella; E. Graziani; H. G. Han; S. W. Han; X. Huang; M. Incagli; L. Ingrosso; L. Keeble; W. Kim; C. Kuo; G. Lanfranchi; J. Lee-Franzini; T. Lomtadze; C. S. Mao; M. Martemianov; W. Mei; R. Messi; S. Miscetti; S. Moccia; M. Moulson; S. Müller; F. Murtas; L. Pacciani; M. Palomba; M. Palutan; E. Pasqualucci; L. Passalacqua; A. Passeri; D. Picca; G. Pirozzi; L. Pontecorvo; M. Primavera; P. Santangelo; E. Santovetti; G. Saracino; R. D. Schamberger; B. Sciascia; F. Scuri; I. Sfiligoi; P. Silano; T. Spadaro; E. Spiriti; L. Tortora; P. Valente; B. Valeriani; G. Venanzoni; A. Ventura; S. Wölfle; Y. Wu; Y. G. Xie; P. F. Zema; C. D. Zhang; J. Q. Zhang; P. P. Zhao

2002-01-01

282

Banded electromagnetic stator core  

DOEpatents

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.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1994-01-01

283

Banded electromagnetic stator core  

DOEpatents

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.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1996-01-01

284

Isotropic metamaterial electromagnetic lens  

Microsoft Academic Search

Several authors have recently exhibited the focusing activity in the domain of so-called electromagnetic lenses. These lenses are parallel-plate layers of metamaterials whose properties can be described in terms of negative index of refraction. Known works on this subject refer to 2D structures. This work is our first attempt to show the focusing effect by a parallel-plate layer of a

E. Verney; B. Sauviac; C. R. Simovski

2004-01-01

285

Method of electromagnetic exploration  

SciTech Connect

A method is described of electromagnetic exploration comprising the following steps: obtaining measures of two horizontal components of the earth's magnetic field at each reference sites; obtaining a measure of the vertical component of the earth's magnetic field for at least one exploratory site; and determining a measure of a multidimensional earth resistivity structure by correlating the measures of horizontal and vertical components of the earth's magnetic field.

Nekut, A.G. Jr.

1987-05-05

286

Electromagnetic tornadoes in space  

SciTech Connect

The exotic phenomenon of energetic-ion conic formation by plasma waves in the magnetosphere is considered. Two particular transverse heating mechanisms are reviewed in detail; lower-hybrid energization of ions in the boundary layer of the plasma sheet and electromagnetic ion cyclotron resonance heating in the central region of the plasma sheet. Mean particle calculations, plasma simulations and analytical treatments of the heating processes are described.

Chang, T.; Crew, G.B.; Retterer, J.M.

1988-01-01

287

Nuclear Electromagnetic Pulse Review  

NASA Astrophysics Data System (ADS)

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.

Dinallo, Michael

2011-04-01

288

Emergent electromagnetism in solids  

NASA Astrophysics Data System (ADS)

The electromagnetic field (EMF) is the most fundamental field in condensed-matter physics. Interaction between electrons, electron-ion interaction and ion-ion interaction are all of electromagnetic origin, while the other three fundamental forces, i.e. the gravitational force and weak and strong interactions, are irrelevant in the energy/length scales of condensed-matter physics. Also the physical properties of condensed matter, such as transport, optical, magnetic and dielectric properties, are almost described as their electromagnetic responses. In addition to this EMF, it often happens that the gauge fields appear as the emergent phenomenon in the low-energy sector due to the projection of the electronic wavefunctions onto the curved manifold of the Hilbert sub-space. These emergent EMFs play important roles in many places in condensed-matter physics including the quantum Hall effect, strongly correlated electrons and also in non-interacting electron systems. In this paper, we describe the fundamental idea behind it and some of its applications studied recently.

Nagaosa, Naoto; Tokura, Yoshinori

2012-01-01

289

Integrated Circuit Electromagnetic Immunity Handbook  

NASA Astrophysics Data System (ADS)

This handbook presents the results of the Boeing Company effort for NASA under contract NAS8-98217. Immunity level data for certain integrated circuit parts are discussed herein, along with analytical techniques for applying the data to electronics systems. This handbook is built heavily on the one produced in the seventies by McDonnell Douglas Astronautics Company (MDAC, MDC Report E1929 of 1 August 1978, entitled Integrated Circuit Electromagnetic Susceptibility Handbook, known commonly as the ICES Handbook, which has served countless systems designers for over 20 years). Sections 2 and 3 supplement the device susceptibility data presented in section 4 by presenting information on related material required to use the IC susceptibility information. Section 2 concerns itself with electromagnetic susceptibility analysis and serves as a guide in using the information contained in the rest of the handbook. A suggested system hardening requirements is presented in this chapter. Section 3 briefly discusses coupling and shielding considerations. For conservatism and simplicity, a worst case approach is advocated to determine the maximum amount of RF power picked up from a given field. This handbook expands the scope of the immunity data in this Handbook is to of 10 MHz to 10 GHz. However, the analytical techniques provided are applicable to much higher frequencies as well. It is expected however, that the upper frequency limit of concern is near 10 GHz. This is due to two factors; the pickup of microwave energy on system cables and wiring falls off as the square of the wavelength, and component response falls off at a rapid rate due to the effects of parasitic shunt paths for the RF energy. It should be noted also that the pickup on wires and cables does not approach infinity as the frequency decreases (as would be expected by extrapolating the square law dependence of the high frequency roll-off to lower frequencies) but levels off due to mismatch effects.

Sketoe, J. G.

2000-08-01

290

Coherent hybrid electromagnetic field imaging  

DOEpatents

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.

Cooke, Bradly J. (Jemez Springs, NM); Guenther, David C. (Los Alamos, NM)

2008-08-26

291

On Inelastic Response Spectra for Aseismic Design.  

National Technical Information Service (NTIS)

The sources of variability in inelastic response spectra, namely, strong ground motion duration, ductility level, and viscous damping ratio, are investigated. From time history analysis, it is concluded that the Newmark inelastic response spectrum for ela...

E. H. Vanmarcke J. M. Biggs S. S. P. Lai

1978-01-01

292

Crack spectra analysis  

SciTech Connect

Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

Tiernan, M.

1980-09-01

293

Cognitive Effects of Electromagnetic Fields in Humans  

Microsoft Academic Search

\\u000a Electromagnetic fields interact with human tissue in a number of ways, depending on power level and frequency, and have been\\u000a long suspected by some to give rise to harmful effects. In particular, the use of a mobile phone against the head has aroused\\u000a suspicions of various cognitive effects. Accordingly, there have been a large number of studies of behavioural effects

Alan W. Preece

294

Electromagnetic field and cosmic censorship  

NASA Astrophysics Data System (ADS)

We construct a gedanken experiment in which an extremal Kerr black hole interacts with a test electromagnetic field. Using Teukolsky's solutions for electromagnetic perturbations in Kerr spacetime, and the conservation laws imposed by the energy momentum tensor of the electromagnetic field and the Killing vectors of the spacetime, we prove that this interaction cannot convert the black hole into a naked singularity, thus cosmic censorship conjecture is not violated in this case.

Düzta?, Koray

2014-04-01

295

Plane Electromagnetic Wave in PEMC  

Microsoft Academic Search

Plane electromagnetic wave propagating in perfect electromagnetic conductor\\u000a(PEMC) is considered. Its wave number has no connection with the frequency. An\\u000ainterface is introduced between an ordinary isotropic medium and PEMC. The wave\\u000ain PEMC is matched to plane electromagnetic wave incident normally on the\\u000ainterface from the ordinary medium and reflected from it. Then the\\u000aplane-parallel slab made of

Bernard Jancewicz

2006-01-01

296

Electromagnetic Theory 3 Volume Set  

NASA Astrophysics Data System (ADS)

Volume 1: Preface; 1. Introduction; 2. Outline of the electromagnetic connections; 3. The elements of vectorial algebra and analysis; 4. Theory of plane electromagnetic waves; Appendix. Volume 2: Preface; 5. Mathematics and the age of the earth; 6. Pure diffusion of electric displacement; 7. Electromagnetic waves and generalised differentiation; 8. Generalised differentiation and divergent series; Appendix. Volume 3: 9. Waves from moving sources; 10. Waves in the ether.

Heaviside, Oliver

2011-09-01

297

Does “electromagnetic pollution” cause illness?  

Microsoft Academic Search

Summary More and more self-declared electromagnetic hypersensitive patients are entering physicians’ practices seeking help. To assess the prevalence of cases and the opinion of Austrian physicians regarding the potential health-relevance of environmental electromagnetic fields (“electromagnetic pollution”), a statistical investigation among general practitioners was undertaken, with surprising results. Only one-third report on never having been asked about the health impact of

Norbert Leitgeb; Jörg Schröttner; Michael Böhm

2005-01-01

298

Electromagnetic Turbulence Simulations with Kinetic Electrons  

NASA Astrophysics Data System (ADS)

Recently a new electromagnetic kinetic electron delta-f particle simulation model has been demonstrated to work well at large values of plasma beta times the ion-to-electron mass ratio [1,2]. The new simulation presented here uses a generalized split-weight scheme [3,4], where the adiabatic part is adjustable, along with a parallel canonical momentum formulation [5] and has been developed in three-dimensional toroidal flux-tube geometry. The model also includes electron-ion collisional effects and has been linearly benchmarked with continuum codes [6,7]. Electromagnetic simulations with kinetic electrons require a timestep approximately one-half that of electrostatic adiabatic electron simulations. Large box size simulations of 256 by 256 in units of ion gyroradius using a realistic mass ratios run well and detailed convergence studies have been done. Finite-beta reduction of energy transport, below the adiabatic electron level is observed for betas below the kinetic ballooning limit. For beta above the kinetic ballooning threshold fluxes are extremely high, and it is unlikely to be an experimentally relevant regime. 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. We have shown that the linear behavior of the zonal flow is not significantly affected by kinetic electrons. Zonal fields [9] are found to be very weak consistent with theoretical predictions for betas below the kinetic ballooning limit. Detailed spectral and cross-correlation analysis of the turbulent spectra will be presented in the various limits. Acknowledgments: Thanks to A.M. Dimits, D. Shumaker, LLNL; V.K. Decyk, J.N. Leboeuf UCLA, work done using the Summit Framework and supported by the DOE SciDAC Plasma Microturbulence Project. [1] Y. Chen and S.E. Parker, to appear in J. Comput. Phys. (2003). [2] Y. Chen, S.E. Parker, B.I. Cohen, A.M. Dimits, W.M. Nevins, D. Shumaker, V.K. Decyk and J.N. Leboeuf, to appear in Nuc. Fusion (2003). [3] I. Manuilskiy and W.W. Lee, Phys. Plasmas 7 1381 (2000). [4] Y. Chen and S.E. Parker, Phys. Plasmas 8 2095 (2001) [5] T.S. Hahm, W.W. Lee and A. Brizard, Phys. Fluids 31 1940 (1988). [6] W. Dorland et. al, Proc. 18th Int. Conf. on Fusion Energy, IAEA, Sorrento, Italy, 2000; W. Dorland, F. Jenko, M. Kotschenreuther and B.N. Rogers, Phys. Rev. Lett. 85, 5336 (2000). [7] J. Candy and R. Waltz, to appear in J. Comput. Physics (2003). [8] A.V. Gruzinov and P.H. Diamond, Phys. Plasmas 3 1854 (1996), L. Chen, Z. Lin R.B. White and F. Zonca, Nuc. Fusion 41 747 (2001); P.N. Gudzar, R.G. Kleva, A. Das and P.K. Kaw, Phys. Plasmas 8 3907 (2001).

Parker, Scott E.

2003-10-01

299

Photon hole nondemolition measurement scheme by electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

We propose a scheme for quantum nondemolition measurement of photon holes based on electromagnetically induced transparency, which allows direct nondestructive detection of the photon holes. We analyze a scheme based on interaction of a photon hole signal and a coherent probe field with a three-level atomic medium. Using recent advances in electromagnetically induced transparency technology, we show that the measurement is nondestructive for very weak photon hole signals.

Rosenblum, Serge; Hayat, Alex; Ginzburg, Pavel; Neiman, David; Orenstein, Meir

2010-05-01

300

Radio frequency electromagnetic fields: mild hyperthermia and safety standards  

Microsoft Academic Search

This chapter is a short review of literature that serves as the basis for current safe exposure recommendations by ICNIRP (International Commission on Non-Ionizing Radiation Protection, 1998). and the IEEE C95.1 (IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3kHz to 300GHz, 2005) for exposure to radio frequency electromagnetic radiation (RF-EMF). Covered here

John A. D’Andrea; John M. Ziriax; Eleanor R. Adair

2007-01-01

301

An inverse problem in the theory of stochastic electromagnetic beams  

Microsoft Academic Search

The cross-spectral density matrix of an electromagnetic beam has been playing increasingly important role in studies of changes of spectra, of coherence and of polarization as the beam propagates. In this paper we derive solution to an inverse problem, which makes it possible to determine the cross-spectral density matrix of the beam in the source plane z=0, from the knowledge

David Kuebel; Mayukh Lahiri; Emil Wolf

2009-01-01

302

Universality of velocity spectra  

Microsoft Academic Search

The purpose of this paper is to present unified spectral models for the three-component velocity fluctuations observed in wind-tunnel generated shear flows and in the atmospheric boundary layer. Presently, only empirical models exist whose coefficients are based on the matching of these models with observed spectra. A general spectral model is presented which can be closely matched to velocity spectra

H. W. Tieleman

1995-01-01

303

Libraries of Stellar Spectra  

NSDL National Science Digital Library

This is a guide to online and abstract libraries of stellar spectra. This reference list also includes information about the spectra of Late-M, L, and T Dwarf stars, Morgan-Keenan spectral classification, the solar spectrum, spectrophotometric atlases, and automated and neural network classification.

2005-04-25

304

Spectra of porphyrins  

Microsoft Academic Search

The review opens by presenting the absorption spectra for three series of porphyrins derived from the basic skeleton: (a) compounds obtained by simple substitution; (b) compounds obtained by reduction of one or more pyrrole rings; and (c) compounds obtained from fusion of aromatic rings onto the basic skeleton. The spectra are discussed in terms of a four orbital model-that is

Martin Gouterman

1961-01-01

305

Optical Spectra of Supernovae  

Microsoft Academic Search

The temporal evolution of the optical spectra of various types of supernovae (SNe) is illustrated, in part to aid observers classifying supernova candidates. Type II SNe are defined by the presence of hydrogen, and they exhibit a very wide variety of photometric and spectroscopic properties. Among hydrogen-deficient SNe (Type I), three subclasses are now known: those whose early-time spectra show

Alexei V. Filippenko

1997-01-01

306

Spectra from Space  

NSDL National Science Digital Library

This site from the Exploratorium provides information on telescopes and observatories such as the Hubble Space Telescope that are being used to study spectra from space. Gamma-ray, x-ray, ultraviolet, and infrared spectra are all examined. The purpose and discoveries made by each observatory are included along with related hands-on activities like a liquid crystal IR detector activity.

Felter, Neil

2006-07-20

307

Electromagnetic pump stator coil  

DOEpatents

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.

Fanning, Alan W. (San Jose, CA); Dahl, Leslie R. (Livermore, CA)

1996-01-01

308

Electromagnetic pump stator coil  

DOEpatents

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.

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

1996-06-25

309

Electromagnetic transitions in hypernuclei  

SciTech Connect

The object of this review is to survey observations of electromagnetic transitions in hypernuclei and to point out contributions of these observations to an understanding of the effective two-body hyperon-nucleon forces in the nucleus. The discussion concentrates on lambda-hyperon nucleon potentials. Future plans for high resolution hypernuclear spectroscopy using Ge diode detectors is discussed, especially regarding the window of utility of such devices. Expected improvements in beam facilities are also reviewed. 9 refs., 4 figs., 1 tab. (DWL)

Chrien, R.E.

1986-01-01

310

Electro-magnetic compatibility  

NASA Astrophysics Data System (ADS)

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.

Maidment, H.

1980-05-01

311

Metamaterials beyond electromagnetism  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

312

Electromagnetic fuel injection valve  

SciTech Connect

An electromagnetic fuel injection valve is described comprising: (a) a housing made of a magnetic material; (b) a valve which opens and closes a fuel injection port that is hydraulically connected to the interior of the housing; (c) a moving core which drives the valve; (d) a fuel guide member which consists of a large diameter portion that is secured to the housing on the side opposite to the fuel injection port. A stationary core extends from the large diameter portion to protrude into the housing. A connection portion extends from the large diameter portion to protrude toward the outer side of the housing, and a penetration path extends from the protruding end of the stationary core to the protruding end of the connection portion; (e) an electromagnetic coil disposed in an annular space defined by the outer periphery of the stationary core and the inner periphery of the housing; (f) a tubular member which is disposed in the penetration path and which has openings at its both ends; and (g) sealing means which hydraulically seals the area between the outer periphery of the tubular member and the inner periphery of the penetration path at an end portion on the side of the fuel injection port of the tubular member.

Soma, M.; Atago, T.; Kido, T.

1986-12-02

313

Electromagnetic Field Penetration Studies  

NASA Technical Reports Server (NTRS)

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.

Deshpande, M.D.

2000-01-01

314

[Recommendations for protection against electromagnetic interference risk caused by pacemakers and implantable defibrillators in hospitals].  

PubMed

Electromagnetic interference and compatibility are problems that claim an increasing attention of biomedical industries, all over the world. For electromagnetic interference we intend a phenomenon that can occur when an electronic device undergoes the influence of an electromagnetic field, which may cause temporary or definitive malfunctioning of the device itself. Indeed, electromagnetic compatibility is the capacity of an electric device either to operate normally, without generating electromagnetic disturbances that may interfere with other devices or to operate without being influenced by electromagnetic field generated by other electric devices. Pacemaker (PM) and implantable-cardioverter defibrillator (ICD) functioning can be significantly compromised by electromagnetic fields, even though their circuits, nowadays, are well protected from most of electromagnetic wave sources. The basis for electromagnetic interference on PM and ICD lays on different factors even physical such as the power of external signal, the distance between the signal and the PM and ICD, the frequency range, modulation type and immunity level of the PM and ICD. The electromagnetic interference on PM and ICD may result into a temporary or permanent malfunctioning, like pacing inhibition, asynchronous pacing, or the switching of the pacing mode. The purpose of this work is to give useful indications for a correct in-hospital management of patients with PM or ICD, in order to avoid dangerous electromagnetic interference. PMID:12025389

Santomauro, Maurizio; Da Prato, Danilo; Ottaviano, Luca; Borrelli, Alessio; Chiariello, Massimo

2002-04-01

315

New Scheme for Electromagnetic Simulations  

Microsoft Academic Search

A new explicit time stepping scheme for electromagnetic simulations is described, the neo-finite-difference method. This numerical method which describes the time derivative as an arc instead of a straight line is more accurate. Thus, larger time steps can be used than with the standard leapfrog method. We start by Fourier analyzing the electromagnetic field in space. The Fourier amplitudes obey

K. R. Chen; J. M. Dawson

1995-01-01

316

Electromagnetic Navigation during Flexible Bronchoscopy  

Microsoft Academic Search

Background: Flexible bronchoscopy is routinely utilized in the diagnosis and treatment of various lung diseases. Nondiagnostic bronchoscopy leads to more invasive interventions, such as transthoracic needle aspiration, mediastinoscopy or even thoracotomy. Electromagnetic navigation is a novel technology that facilitates approaching peripheral lung lesions, which are difficult to sample by conventional means. The navigation system involves creating an electromagnetic field around

Yehuda Schwarz; Atul C. Mehta; Armin Ernst; Felix Herth; Ahuva Engel; Doron Besser; Heinrich D. Becker

2003-01-01

317

Particle swarm optimization in electromagnetics  

Microsoft Academic Search

The particle swarm optimization (PSO), new to the electromagnetics community, is a robust stochastic evolutionary computation technique based on the movement and intelligence of swarms. This paper introduces a conceptual overview and detailed explanation of the PSO algorithm, as well as how it can be used for electromagnetic optimizations. This paper also presents several results illustrating the swarm behavior in

Jacob Robinson; Yahya Rahmat-Samii

2004-01-01

318

Exploration of the Electromagnetic Environment  

ERIC Educational Resources Information Center

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…

Fullekrug, M.

2009-01-01

319

Lily Pad Spectra  

NASA Technical Reports Server (NTRS)

The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.

2004-01-01

320

[Safety and electromagnetic compatibility in sanitary field].  

PubMed

In sanitary field and especially in a hospital, multiple sources of non ionizing radiation are used for diagnostic and therapeutic aims. In sanitary sector both workers and users are present at the same time, and in some cases general population could need higher protection than workers in relationship to the exposition to electromagnetic fields. In order to protect health and safety of patients, general population and workers of hospitals and with the aim to identify, analyze, evaluate and study its level of significance, electrical, magnetic and electromagnetic sources Research Italian project Si.C.E.O. (Safety And Electromagnetic Compatibility In Sanitary Field) was instituted. Target of our research project was to deepen risk of exposition elements with analysis of outdoor (e.g. power lines, transmission cabinets) and indoor (e.g. equipment for physical therapy) sources, located in sanitary structures and to verify the level exposition of workers and common population end the respect of specific regulation, and finally to define technical and organizational measures really useful for protection and reduction of risk. PMID:23405726

Bini, M; Feroldi, P; Ferri, C; Ignesti, A; Olmi, R; Priori, S; Riminesi, C; Tobia, L

2012-01-01

321

Gravitational scattering of electromagnetic radiation  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

322

Radiated fields from an electromagnetic pulse simulator  

NASA Astrophysics Data System (ADS)

Simulators of electromagnetic pulses allow generation within a limited time of very high-intensity fields such as those produced in a nuclear explosion. These fields can be radiated out of the test zone at a lower but nevertheless significant level; if the intensity of these fields is sufficiently high, damage to humans and electronic equipment can result. An evaluation of the potential danger of these simulator emissions requires knowledge of the amplitude, duration, and the energy of the radiated impulses. A technique is presented for calculating the fields radiated by a parallel-plane electromagnetic pulse simulator. The same method can also be applied to a rhombic type simulator. Sample numerical results are presented along with the calculations of the energy and power density and a discussion of the formation of the field in the frequency domain.

Pelletier, M.; Delisle, G. Y.; Kashyap, S.

323

Coherent spin control by electromagnetic vacuum fluctuations  

SciTech Connect

In coherent control, electromagnetic vacuum fluctuations usually cause coherence loss through irreversible spontaneous emission. However, since the dissipation via emission is essentially due to correlation of the fluctuations, when emission ends in a superposition of multiple final states, correlation between different pathways may build up if the 'which way' information is not fully resolved (i.e., the emission spectrum is broader than the transition energy range). Such correlation can be exploited for spin-flip control in a {Lambda}-type three-level system, which manifests itself as an all-optical spin echo in nonlinear optics with two orders of optical fields saved as compared with stimulated Raman processes. This finding represents a class of optical nonlinearity induced by electromagnetic vacuum fluctuations.

Wang Jing [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Department of Physics, Tsinghua University, Beijing 100084 (China); Liu Renbao [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Zhu Bangfen [Department of Physics, Tsinghua University, Beijing 100084 (China); Institute of Advanced Study, Tsinghua University, Beijing 100084 (China); Sham, L. J. [Department of Physics, University of California-San Diego, La Jolla, California 92093-0319 (United States); Steel, D. G. [H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-05-15

324

Electromagnetic radiation from beam-plasma instabilities  

NASA Technical Reports Server (NTRS)

A computer simulation is developed for the generation of electromagnetic radiation in an electron beam-plasma interaction. The plasma is treated as a two-dimensional finite system, and effects of a continuous nonrelativistic beam input are accounted for. Three momentum and three field components are included in the simulation, and an external magnetic field is excluded. EM radiation generation is possible through interaction among Langmuir oscillations, ion-acoustic waves, and the electromagnetic wave, producing radiation perpendicular to the beam. The radiation is located near the plasma frequency, and polarized with the E component parallel to the beam. The scattering of Langmuir waves caused by ion-acoustic fluctuations generates the radiation. Comparison with laboratory data for the three-wave interactions shows good agreement in terms of the radiation levels produced, which are small relative to the plasma thermal energy.

Pritchett, P. L.; Dawson, J. M.

1983-01-01

325

Spectra from Space  

NSDL National Science Digital Library

This resource explains why we go to the expense of launching satellites to gather spectral data in space. The earth's atmosphere does not allow light of all wavelengths to pass through it. In order to see gamma, X ray, ultraviolet (UV), infrared, and microwave radiation, we must place telescopes and other light-gathering instruments above the atmosphere. At this site, students investigate satellite missions operating in four electromagnetic bands using the internet and hands-on activities. After successfully completing these activities, students will be able to identify four different regions of the electromagnetic spectrum and order them by wavelength, describe one or more of the four satellite missions featured in the site, its capabilities, and some objects it is used to observe, and conduct and draw appropriate conclusions from some or all of four hands-on activities.

326

Electromagnetic interference onboard an electrically propelled spacecraft  

NASA Technical Reports Server (NTRS)

Electric and magnetic interference generated by a power conditioner and ion thruster were measured at JPL. Test results were judged by comparing the measured levels to the levels defined by the solar electric propulsion (SEP) specification that was derived from the existing mission oriented Viking-Orbiter 1975 and Mariner-Jupiter-Saturn 1977 electromagnetic compatibility specifications. In many areas the measured interference was excessive. In some cases, the cause of interference was identified. It was concluded that it should be possible on future designs to improve the EMI characteristics greatly at a modest penalty to weight and efficiency.

Macie, T. W.; Whittlesey, A. C.

1973-01-01

327

Spectra over complex terrain  

SciTech Connect

Spectra have been measured over land downwind of a water surface, over hilltops and escarpments, and over rolling farmland. The following hypotheses can be used to explain the differences between these spectra. (1) For wavelengths short compared to the fetch over the new terrain, spectral densities are in equilibrium with the new terrain. (2) For wavelengths long compared to this fetch, spectral densities remain unchanged if the ground is horizontal. If the flow is over a steep hill, the low-frequency structure is modified by distortion of the mean flow, with the longitudinal component losing energy relative to the lateral and vertical components. Because vertical-velocity spectra contain relatively less low-frequency energy than horizontal-velocity spectra, energetic vertical-velocity fluctuations tend to be in equilibrium with local terrain.

Panofsky, H.A.; Larko, D.; Lipschutz, R.; Stone, G.

1981-01-01

328

Mass spectra of benzylpyridines  

Microsoft Academic Search

The mass spectra of dimethylbenzyl- and dimethyldibenzylpyridines at different ionizing electron energies were investigated. The anomalously low intensities of the molecular ion peaks of 3,4-dibenzylpyridines, as compared with the 2,5-isomers, and the greater probability of the formation of primary (M-2)+ ions in the mass spectra are explained by the synchronous loss of a neutral H2 particle and the formation of

P. B. Terent'ev; R. A. Khmel'nitskii; N. A. Klyuev; A. B. Belikov; V. V. Dorogov

1973-01-01

329

The Electromagnetic Spectrum  

NSDL National Science Digital Library

In this lesson, students are introduced to the electromagnetic spectrum. They observe a demonstration of the visible light spectrum created by a flashlight and a prism, complete an activity sheet where they identify the wavelength that is involved in technologies used in their communities, and learn about satellite sensors that remotely sense data. Student worksheets, a data sheet, answer keys, and Web links are included. This is Lesson 3 in Understanding Light, part of IMAGERS, Interactive Media Adventures for Grade School Education using Remote Sensing. The website provides hands-on activities in the classroom supporting the science content in two interactive media books, The Adventures of Echo the Bat and Amelia the Pigeon.

330

Novel electromagnetic accelerometer  

NASA Astrophysics Data System (ADS)

A novel micro-accelerometer based on electromagnetic field induction has been fabricated from Si (100) wafers using silicon micro machining techniques. For this design, measurements of acceleration ranging from 0-50 g have been experimentally demonstrated. The physical structure and a brief description of the fabrication process is given. The actual size of the device is 4.2 x 4.2 mm, its amplified output voltage varies linearly from 0-9 V with the rate of 0.175 V/g and the power consumption is less than 2.5 mW. Due to the simple structure a batch processing with on chip signal conditioning circuitry is possible. The required electronic circuitry compared to the capacitive accelerometers is much simpler.

Abbaspour-Sani, Ebrahim; Huang, Ruey-Shing; Kwok, Chee Yee

1994-08-01

331

Electromagnetic propulsion for spacecraft  

NASA Technical Reports Server (NTRS)

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.

Myers, Roger M.

1993-01-01

332

Superconducting electromagnetic thruster  

NASA Astrophysics Data System (ADS)

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.

Meng, James C.

1994-08-01

333

Superconducting electromagnetic thruster  

SciTech Connect

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.

Meng, J.

1993-02-11

334

Causal electromagnetic interaction equations  

SciTech Connect

For the electromagnetic interaction of two particles the relativistic causal quantum mechanics equations are proposed. These equations are solved for the case when the second particle moves freely. The initial wave functions are supposed to be smooth and rapidly decreasing at the infinity. This condition is important for the convergence of the integrals similar to the integrals of quantum electrodynamics. We also consider the singular initial wave functions in the particular case when the second particle mass is equal to zero. The discrete energy spectrum of the first particle wave function is defined by the initial wave function of the free-moving second particle. Choosing the initial wave functions of the free-moving second particle it is possible to obtain a practically arbitrary discrete energy spectrum.

Zinoviev, Yury M. [Steklov Mathematical Institute, Gubkin Street 8, 119991, Moscow (Russian Federation)

2011-02-15

335

Electromagnetically Clean Solar Arrays  

NASA Technical Reports Server (NTRS)

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 wiring on the back of the panel. Each step increases the potential for occurrence of latent defects, loss of process control, and attrition of components. An EMCSA panel includes an integral cover made from a transparent material. The silicone cover supplants the individual cover glasses on the cells and serves as an additional unitary structural support that offers the advantage, relative to glass, of the robust, forgiving nature of the silcone material. The cover contains pockets that hold the solar cells in place during the lamination process. The cover is coated with indium tin oxide to make its surface electrically conductive, so that it serves as a contiguous, electrically grounded shield over the entire panel surface. The cells are mounted in proximity to metallic printed wiring. The painted-wiring layer comprises metal-film traces on a sheet of Kapton (or equivalent) polyimide. The traces include contact pads on one side of the sheet for interconnecting the cells. Return leads are on the opposite side of the sheet, positioned to form the return currents substantially as mirror images of, and in proximity to, the cell sheet currents, thereby minimizing magnetic moments. The printed-wiring arrangement mimics the back-wiring arrangement of conventional solar arrays, but the current-loop areas and the resulting magnetic moments are much smaller because the return-current paths are much closer to the solar-cell sheet currents. The contact pads are prepared with solder fo electrical and mechanical bonding to the cells. The pocketed cover/shield, the solar cells, the printed-wiring layer, an electrical bonding agent, a mechanical-bonding agent, a composite structural front-side face sheet, an aluminum honeycomb core, and a composite back-side face sheet are all assembled, then contact pads are soldered to the cells and the agents are cured in a single lamination process.

Stem, Theodore G.; Kenniston, Anthony E.

2008-01-01

336

Electromagnetic inverse scattering  

NASA Technical Reports Server (NTRS)

A three-dimensional electromagnetic inverse scattering identity, based on the physical optics approximation, is developed for the monostatic scattered far field cross section of perfect conductors. Uniqueness of this inverse identity is proven. This identity requires complete scattering information for all frequencies and aspect angles. A nonsingular integral equation is developed for the arbitrary case of incomplete frequence and/or aspect angle scattering information. A general closed-form solution to this integral equation is developed, which yields the shape of the scatterer from such incomplete information. A specific practical radar solution is presented. The resolution of this solution is developed, yielding short-pulse target resolution radar system parameter equations. The special cases of two- and one-dimensional inverse scattering and the special case of a priori knowledge of scatterer symmetry are treated in some detail. The merits of this solution over the conventional radar imaging technique are discussed.

Bojarski, N. N.

1972-01-01

337

Nucleon Electromagnetic Form Factors  

SciTech Connect

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.

Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi

2007-10-01

338

THE ELECTROMAGNET. A SUPPLEMENTARY READING UNIT IN SCIENCE.  

ERIC Educational Resources Information Center

A SAMPLE READING UNIT IN SCIENCE IS PRESENTED FOR DISADVANTAGED STUDENTS AT THREE LEVELS OF ABILITY. THE READING LESSON IS COMPLETE WITH ILLUSTRATIONS OF ELECTROMAGNETS. FOLLOWING THE SUPPLEMENTARY UNIT ARE THREE SAMPLE OBJECTIVE TESTS FOR THE DIFFERENT ABILITY LEVELS. EACH SET OF QUESTIONS IS DESIGNED BOTH TO TEST KNOWLEDGE OF SCIENCE FACTS…

KINNEY, RICHARD; MOBILIZATION FOR YOUTH CURRICULUM STAFF

339

PAH Spectra for Everyone  

NASA Astrophysics Data System (ADS)

The Ames Astrochemistry Laboratory now has PAH IR spectra of more than 220 laboratory measured and over 600 theoretically calculated IR spectra of polycyclic aromatic hydrocarbons (PAHs) in a multitude of forms. The vast majority of these spectra are not readily accessible to the public. We propose to make the full collection of the Ames experimental and computational collection of PAH IR spectra available to the entire Spitzer community and accessible via the World Wide Web (WWW). The laboratory measured mid-IR spectral collection includes over 220 neutral, cationic, and anionic PAHs, PAHs with deuterium in place of hydrogen, PAHs containing oxygen, and PAHs containing nitrogen (PANHs). The formulae of the PAHs in the experimental data collection range from C10H8 to C50H22. Unfortunately, it is not possible to obtain physical samples of all of the types of PAHs that are of astrophysical interest for experimental study. We also have an extensive collection of accurate computational spectra to fill in gaps in the experimentally available spectra. Our theoretical PAH spectral collection includes very large PAHs, PAHs containing 40 to 132 carbon atoms which are comparable to the size of the PAHs thought to dominate the interstellar emission spectrum. Large PAHs might be multiply charged and these are also represented in the theoretical database. There is also observational evidence for PAH cations with nitrogen in the inner rings (PANHs) and interest in the spectroscopy of aromatic species containing oxygen and deuterium as well as PAH metal clusters. All of these types of PAHs are represented in the Ames computational PAH IR spectroscopic collection. If funded, we plan to make our entire inventory of the lab spectra available to the Spitzer community within the next two years.

Allamandola, Louis; Bauschlicher, Charlie, Jr.; Mattioda, Andrew

2007-05-01

340

Electromagnetically induced self-imaging  

NASA Astrophysics Data System (ADS)

We study the self-imaging and image-transforming properties of a probe field in a cold atomic medium with electromagnetically induced transparency (EIT). Due to the similarities between the gradient-index medium and the inhomogeneous index distribution of an EIT medium under the conditions of a negative probe detuning and a Gaussian control field, we find based on analytical investigations that there exists a kind of electromagnetically induced self-imaging phenomenon in cold atomic media. Numerical simulations clearly show that electromagnetically induced self-imaging is observable and controllable.

Cheng, Jing; Han, Shensheng

2007-05-01

341

Electromagnetic Field Effects in Explosives  

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

342

THz absorption spectra and stability of Fe water complexes calculated by density functional theory  

NASA Astrophysics Data System (ADS)

Monitoring of water contaminants implies a need for determining their dielectric response properties with re- spect to electromagnetic wave excitation at various frequencies. Iron is a naturally occurring water contaminant resulting from decaying vegetation, which is at much higher concentrations than any other metal contaminant. The present study uses density functional theory (DFT) for the calculation of ground state resonance struc- ture and molecular stability analysis for Fe water complexes. The calculations presented are for excitation by electromagnetic waves at frequencies within the THz range. Dielectric response functions calculated by DFT can be used for the analysis of water contaminants. These functions provide quantitative initial estimates of spectral response features for subsequent adjustment with respect to additional information such as laboratory measurements and other types of theory based calculations. In addition, with respect to qualitative analysis, DFT calculated absorption spectra provide for molecular level interpretation of response structure. The DFT software GAUSSIAN was used for the calculations of ground state resonance structure presented here.

Huang, L.; Lambrakos, S. G.; Shabaev, A.; Massa, L.; Yapijakis, C.

2013-05-01

343

From the electromagnetic pulse to high-power electromagnetics  

Microsoft Academic Search

Since the 1960s significant effort has gone into developing requisite technology for the nuclear electromagnetic pulse (EMP). In the late 1970s several important summary documents were published. The author updates this information to the present. It is noted that EMP has affected a set of related areas which can be collectively referred to as high-power electromagnetics (HPE). This includes direct-strike

CARL E. BAUM

1992-01-01

344

Comparison between electroglottography and electromagnetic glottography  

SciTech Connect

Newly developed glottographic sensors, utilizing high-frequency propagating electromagnetic waves, were compared to a well-established electroglottographic device. The comparison was made on four male subjects under different phonation conditions, including three levels of vocal fold adduction (normal, breathy, and pressed), three different registers (falsetto, chest, and fry), and two different pitches. Agreement between the sensors was always found for the glottal closure event, but for the general wave shape the agreement was better for falsetto and breathy voice than for pressed voice and vocal fry. Differences are attributed to the field patterns of the devices. Whereas the electroglottographic device can operate only in a conduction mode, the electromagnetic device can operate in either the forward scattering (diffraction) mode or in the backward scattering (reflection) mode. Results of our tests favor the diffraction mode because a more favorable angle imposed on receiving the scattered (reflected) signal did not improve the signal strength. Several observations are made on the uses of the electromagnetic sensors for operation without skin contact and possibly in an array configuration for improved spatial resolution within the glottis. (c) 2000 Acoustical Society of America.

Titze, Ingo R. [Department of Speech Pathology and Audiology and National Center for Voice and Speech, The University of Iowa and the Denver Center for the Performing Arts, Iowa City, Iowa 52242 (United States)] [Department of Speech Pathology and Audiology and National Center for Voice and Speech, The University of Iowa and the Denver Center for the Performing Arts, Iowa City, Iowa 52242 (United States); Story, Brad H. [Department of Speech Pathology and Audiology and National Center for Voice and Speech, The University of Iowa and the Denver Center for the Performing Arts, Iowa City, Iowa 52242 (United States)] [Department of Speech Pathology and Audiology and National Center for Voice and Speech, The University of Iowa and the Denver Center for the Performing Arts, Iowa City, Iowa 52242 (United States); Burnett, Gregory C. [Department of Applied Science, University of California at Davis, and Lawrence Livermore National Laboratory, Livermore, California 94557 (United States)] [Department of Applied Science, University of California at Davis, and Lawrence Livermore National Laboratory, Livermore, California 94557 (United States); Holzrichter, John F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ng, Lawrence C. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Lea, Wayne A. [Speech Sciences Institute, Apple Valley, Minnesota 55124 (United States)] [Speech Sciences Institute, Apple Valley, Minnesota 55124 (United States)

2000-01-01

345

Electromagnetic fields stress living cells.  

PubMed

Electromagnetic fields (EMF), in both ELF (extremely low frequency) and radio frequency (RF) ranges, activate the cellular stress response, a protective mechanism that induces the expression of stress response genes, e.g., HSP70, and increased levels of stress proteins, e.g., hsp70. The 20 different stress protein families are evolutionarily conserved and act as 'chaperones' in the cell when they 'help' repair and refold damaged proteins and transport them across cell membranes. Induction of the stress response involves activation of DNA, and despite the large difference in energy between ELF and RF, the same cellular pathways respond in both frequency ranges. Specific DNA sequences on the promoter of the HSP70 stress gene are responsive to EMF, and studies with model biochemical systems suggest that EMF could interact directly with electrons in DNA. While low energy EMF interacts with DNA to induce the stress response, increasing EMF energy in the RF range can lead to breaks in DNA strands. It is clear that in order to protect living cells, EMF safety limits must be changed from the current thermal standard, based on energy, to one based on biological responses that occur long before the threshold for thermal changes. PMID:19268550

Blank, Martin; Goodman, Reba

2009-08-01

346

Electromagnetic Modeling of Display Module Interconnect  

Microsoft Academic Search

This paper deals with the use of the computational electromagnetic modeling into the electromagnetic design (EMD) of an electronic system as apart of design process. In this paper an electric and electromagnetic computational verification flow is suggested. As an application electromagnetic modeling of interconnect of display module is investigated using suggested the EMD computational verification flow

A. N. Arslan; V. Hurskainen; I. Pankinaho; I. Kelander; A. Rautio

2006-01-01

347

Accurate computational method for solving electromagnetic wave  

Microsoft Academic Search

This paper studied in solving monochromatic electromagnetic wave. Under such circumstances of axial symmetric and passive electromagnetic wave that is finite and differentiable on the symmetric axis, a new approximation theory and evolutionary computing method are provided by using Maxwell equations. Out-of-axis electromagnetic wave can be expressed as series with the method. This series contains electromagnetic wave on the symmetric

Li Zijun; Fang Benying

2009-01-01

348

Bobbing and kicks in electromagnetism and gravity  

SciTech Connect

We study systems analogous to binary black holes with spin in order to gain some insight into the origin and nature of 'bobbing' motion and 'kicks' that occur in this system. Our basic tool is a general formalism for describing the motion of extended test bodies in an external electromagnetic field in curved spacetime and possibly subject to other forces. We first show that bobbing of exactly the type as observed in numerical simulations of the binary black hole system occurs in a simple system consisting of two spinning balls connected by an elastic band in flat spacetime. This bobbing may be understood as arising from the difference between a spinning body's 'lab frame centroid' and its true center of mass, and is purely 'kinematical' in the sense that it will appear regardless of the forces holding two spinning bodies in orbit. Next, we develop precise rules for relating the motion of charged bodies in a stationary external electromagnetic field in flat spacetime with the motion of bodies in a weakly curved stationary spacetime. We then consider the system consisting of two orbiting charges with magnetic dipole moment and spin at a level of approximation corresponding to 1.5 post-Newtonian order. Here we find that considerable amounts of momentum are exchanged between the bodies and the electromagnetic field; however, the bodies store this momentum entirely as ''hidden'' mechanical momentum, so that the interchange does not give rise to any net bobbing. The net bobbing that does occur is due solely to the kinematical spin effect, and we therefore argue that the net bobbing of the electromagnetic binary is not associated with possible kicks. We believe that this conclusion holds in the gravitational case as well.

Gralla, Samuel E.; Harte, Abraham I.; Wald, Robert M. [Enrico Fermi Institute and Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States)

2010-05-15

349

Nonlinear evolution of electromagnetic ion cyclotron waves  

SciTech Connect

Hybrid Vlasov-Fourier modeling is used to investigate the nonlinear evolution of electromagnetic ion cyclotron (EMIC) waves driven by proton temperature anisotropy in plasmas with a population of He{sup +} ions and a cold proton background. In the pure proton-electron plasma, most of the free energy is converted into high-amplitude waves and currents. In the nonlinear stage, within a few hundred proton gyroperiods after the saturation, the wave spectrum shifts toward lower wave numbers and frequencies, from {omega}{approx}0.6{Omega}{sub p} to below {omega}{approx}0.25{Omega}{sub p}. In the presence of even a small population of He{sup +} ions almost all of the free energy is used in He{sup +} heating. The wave activity in the saturated state moves from the linearly unstable upper branch to the linearly stable lower one. In the presence of a background of cold protons, the waves can propagate in the frequency stop-band. Our results demonstrate that linear stability theory cannot be used to estimate the characteristics of the expected saturated wave spectra in the terrestrial magnetosphere. Significantly, our nonlinear simulations produce wave spectra which are in close agreement with the EMIC waves observed in situ by satellites as well as by ground-based magnetometers positioned at the ends of the magnetic field lines.

Silin, I.; Sydora, R. D.; Mann, I. R.; Sauer, K. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); Mace, R. L. [School of Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

2011-04-15

350

Measurement of electromagnetic energy flow  

NASA Astrophysics Data System (ADS)

The measurement of electromagnetic energy flow is an integral part of solving radiation-budget and optical-characterization problems. It is therefore very important to understand clearly what specific measurement is afforded by an optical instrument and how to model this measurement theoretically. We will not discuss technical and technological issues related to the development of sensitive and efficient detectors of light. Instead, the discussion will focus on the precise definitions of general measurement principles and their specific practical implications in the framework of electromagnetic scattering by particles and particle groups. We will discuss in succession measurements with direction-insensitive detectors, monodirectional well-collimated, and panoramic well-collimated radiometers. Special attention will be paid to the electromagnetic response of a well-collimated radiometer to polychromatic light. We will see, in particular, that although the main characteristic of electromagnetic energy flow is the Poynting vector, the actual measurement of this quantity is possible only in very special cases.

Mishchenko, M. I.

2012-12-01

351

Vertical Electromagnetic Pulse (VEMP) Testing.  

National Technical Information Service (NTIS)

This TOP provides methods for planning, providing instrumentation, and execution of testing of Army/DOD Materiel to determine the effects of Vertical Component High Altitude Electromagnetic Pulse (VHEMP) Environment on the safety and/or reliability of the...

2009-01-01

352

Electromagnetic Interference In New Aircraft  

NASA Technical Reports Server (NTRS)

Report reviews plans to develop tests and standards to ensure that digital avionics systems in new civil aircraft immune to electromagnetic interference (EMI). Updated standards reflect more severe environment and vulnerabilities of modern avionics.

Larsen, William E.

1991-01-01

353

Electromagnetic Showers at High Energy  

ERIC Educational Resources Information Center

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)

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

1978-01-01

354

Sommerfeld Integrals and Electromagnetic Fields.  

National Technical Information Service (NTIS)

The complete electromagnetic fields for both elementary electric and magnetic dipoles are listed for both horizontal and vertical orientations of the dipoles. All combinations of dipole and field point locations above or below the boundary between two con...

T. W. H. Caffey

1988-01-01

355

Tracking Electromagnetic Energy With SQUIDs.  

National Technical Information Service (NTIS)

A superconducting quantum interference device (SQUID) is a gadget used to measure extremely weak signals, specifically magnetic flux. It can detect subtle changes in energy, up to 100 billion times weaker than the electromagnetic energy required to move a...

2005-01-01

356

Conical electromagnetic radiation flux concentrator  

NASA Technical Reports Server (NTRS)

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.

Miller, E. R.

1972-01-01

357

Electromagnetic Effects in SDF Explosions  

Microsoft Academic Search

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

H Reichenbach; P Neuwald; A L Kuhl

2010-01-01

358

[Electromagnetic field intolerance: a nonexistent disease?].  

PubMed

Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields is a relatively new phenomenon, which is not fully understood. Extensive research has been carried out to exclude or confirm out that symptoms reported by sufferers are caused by electromagnetic field. This article describes outcomes of recent experiments and meta-analyses. The article may answer to the question if electromagnetic field does really cause reported symptoms, furthermore, it provides hypothetical explanation of this phenomenon. Keywords: electromagnetic hypersensitivity - electromagnetic field - nonspecific symptoms - nocebo effect. PMID:24506686

Safá?ová, Sárka

2014-01-01

359

Pulsed electromagnetic gas acceleration  

NASA Technical Reports Server (NTRS)

Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

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

1974-01-01

360

SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS  

SciTech Connect

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.

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

2008-08-01

361

Modern electromagnetic scattering  

NASA Astrophysics Data System (ADS)

We develop a numerically stable algorithm for electromagnetic wave propagation through planar stratified media. This algorithm is implemented in a modern programming language and is suitable for the study of such applications as Anderson localization and perfect lensing. Our algorithm remains numerically stable even in the presence of large absorption. Furthermore, in the context of the linear response laws and causality, we analyze a vanishing absorption approximation, which is commonly used in wave scattering problems. We show that it is easy to violate causality in the frequency-domain by making the vanishing absorption approximation. We also develop an orders-of-scattering approximation, termed "screened cylindrical void/core" (SCV) approximation, for wave scattering from a large host cylinder containing N eccentrically embedded core cylinders. The SCV approximation is developed via separation of variables and a cluster T-matrix. We establish the limitations of the SCV approximation and it is in good agreement with the numerically-exact solution. Furthermore, we illustrate that the large host cylinder model with N cylindrical inclusions can be used to theoretically and experimentally investigate strong multiple scattering effects in random media, such as Anderson localization.

Yuffa, Alex J.

362

Electromagnetic Interference on Pacemakers  

PubMed Central

External sources, either within or outside the hospital environment, may interfere with the appropriate function of pacemakers which are being implanted all around the world in current medical practice. The patient and the physician who is responsible for follow-up of the pacing systems may be confronted with some specific problems regarding the various types of electromagnetic interference (EMI). To avoid these unwanted EMI effects one must be aware of this potential problem and need to take some precautions. The effects of EMI on pacemaker function and precautions to overcome some specific problems were discussed in this review article. There are many sources of EMI interacting with pacemakers. Magnetic resonance imaging creates real problem and should be avoided in pacemaker patients. Cellular phones might be responsible for EMI when they were held on the same side with the pacemaker. Otherwise they don't cause any specific type of interaction with pacemakers. Sale security systems are not a problem if one walks through it without lingering in or near it. Patients having unipolar pacemaker systems are prone to develop EMI because of pectoral muscle artifacts during vigorous active physical exercise.

Erdogan, Okan

2002-01-01

363

Electromagnetically driven peristaltic pump  

DOEpatents

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.

Marshall, Douglas W. (Blackfoot, ID)

2000-01-01

364

Electromagnetism of Bacterial Growth  

NASA Astrophysics Data System (ADS)

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.

Ainiwaer, Ailiyasi

2011-10-01

365

From GEM to electromagnetism  

NASA Astrophysics Data System (ADS)

In the first part of the present work, we focus on the theory of gravitoelectromagnetism (GEM), and we derive the full set of equations and constraints that the GEM scalar and vector potentials ought to satisfy. We discuss important aspects of the theory, such as the presence of additional constraints resulting from the field equations and gauge condition, the requirement of the time-independence of the vector potential and the emergence of additional terms in the expression of the Lorentz force. We also propose an alternative ansatz for the metric perturbations that is found to be compatible only with a vacuum configuration but evades several of the aforementioned obstacles. In the second part of this work, we pose the question of whether a tensorial theory using the formalism of General Relativity could re-produce the theory of Electromagnetism. We demonstrate that the full set of Maxwell's equations can be exactly re-produced for a large class of models, but the framework has several weak points common with those found in GEM.

Bakopoulos, A.; Kanti, P.

2014-06-01

366

Electromagnetic ion beam instabilities  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

367

[The characteristics of the electromagnetic situation close to overhead electric power transmission lines in St. Petersburg].  

PubMed

According to task by Environmental Protection Department of St. Petersburg Municipal Administration, levels of electromagnetic fields induced by high-voltage electric power lines were measured in development lands of St. Petersburg. The authors present hygienic evaluation of electromagnetic fields intensity, match calculated and actual values of magnetic induction of occupational magnetic fields. PMID:9885493

Nikitina, V N; Marchenko, E A; Kolesnikov, G A; Naumova, T M; Shubnikova, N N; Cherniavski?, A A

1998-01-01

368

Some Observable Effects of the Quantum-Mechanical Fluctuations of the Electromagnetic Field  

Microsoft Academic Search

An intuitive explanation is given for the electromagnetic shift of energy levels by calculating the mean square amplitude of oscillation of an electron coupled to the zero-point fluctuations of the electromagnetic field. The resulting disturbance of the charge and current density of the electron gives rise to various observable effects which can be estimated in a simple classical fashion. The

Theodore A. Welton

1948-01-01

369

A distributed system of mobile sensors for electromagnetic field measurements in urban environments  

Microsoft Academic Search

A mobile distributed system for the monitoring and mapping of electromagnetic field exposure levels in urban environments is presented. The main objective of the system, in accordance with current regulations, is to use mapped values to highlight 'critical' locations within the investigated area where the environmental electromagnetic field amplitude is higher, and that therefore need careful observation and monitoring or

Claudio De Capua; Nicola Pasquino; Antonio Maria Rinaldi; Alessandro Scala

2004-01-01

370

Distinguishing low frequency oscillations within the 1\\/f spectral behaviour of electromagnetic brain signals  

Microsoft Academic Search

BACKGROUND: It has been acknowledged that the frequency spectrum of measured electromagnetic (EM) brain signals shows a decrease in power with increasing frequency. This spectral behaviour may lead to difficulty in distinguishing event-related peaks from ongoing brain activity in the electro- and magnetoencephalographic (EEG and MEG) signal spectra. This can become an issue especially in the analysis of low frequency

Charmaine Demanuele; Christopher J James; Edmund JS Sonuga-Barke

2007-01-01

371

Electromagnetic Wave Scattering By a Perfectly Conducting Wedge in Uniform Translational Motion  

Microsoft Academic Search

The exact relativistic solution to the problem of electromagnetic wave scattering by a perfectly conducting wedge in uniform translational motion is obtained on the ground of the Frame Hopping Method; a field representation in terms of plane-wave spectra allows us to apply Special Relativity covariance relations in terms of simple alteration rules for the wave parameters of the spectral components.

P. De Cupis; P. Burghignoli; G. Gerosa; M. Marziale

2002-01-01

372

Quantization noise spectra  

Microsoft Academic Search

Several results describing the behavior of quantization noise in a unified and simplified manner are discussed. Exact formulas for quantizer noise spectra are developed. They are applied to a variety of systems and inputs, including scalar quantization (PCM), dithered PCM, sigma-delta modulation, dithered sigma-delta modulation, two-stage sigma-delta modulation, and second-order sigma-delta modulation

Robert M. Gray

1990-01-01

373

Electromagnetically induced grating with maximal atomic coherence  

SciTech Connect

We describe theoretically an atomic diffraction grating that combines an electromagnetically induced grating with a coherence grating in a double-{Lambda} atomic system. With the atom in a condition of maximal coherence between its lower levels, the combined gratings simultaneously diffract both the incident probe beam as well as the signal beam generated through four-wave mixing. A special feature of the atomic grating is that it will diffract any beam resonantly tuned to any excited state of the atom accessible by a dipole transition from its ground state.

Carvalho, Silvania A.; Araujo, Luis E. E. de [Instituto de Fisica ''Gleb Wataghin'', Universidade Estadual de Campinas, Campinas-SP, 13083-859 Sao Paulo (Brazil)

2011-10-15

374

Structures, systems and methods for harvesting energy from electromagnetic radiation  

DOEpatents

Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.

Novack, Steven D. (Idaho Falls, ID); Kotter, Dale K. (Shelley, ID); Pinhero, Patrick J. (Columbia, MO)

2011-12-06

375

Energy harvesting devices for harvesting energy from terahertz electromagnetic radiation  

DOEpatents

Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.

Novack, Steven D.; Kotter, Dale K.; Pinhero, Patrick J.

2012-10-09

376

Multi-scale roughness spectra of Mount St. Helens debris flows  

NASA Technical Reports Server (NTRS)

A roughness spectrum allows surface structure to be interpreted as a sum of sinusoidal components with differing wavelengths. Knowledge of the roughness spectrum gives insight into the mechanisms responsible for electromagnetic scattering at a given wavelength. Measured spectra from 10-year-old primary debris flow surfaces at Mount St. Helens conform to a power-law spectral model, suggesting that these surfaces are scaling over the measured range of spatial frequencies. Measured spectra from water-deposited surfaces deviate from this model.

Austin, Richard T.; England, Anthony W.

1993-01-01

377

Quantitative experimental determination of scattering and absorption cross-section spectra of individual optical metallic nanoantennas.  

PubMed

Antennas convert propagating radiation to localized electromagnetic energy and to heat. To unambiguously separate between these two aspects, one needs to quantitatively determine the antenna scattering and absorption cross-section spectra. By using a spatial modulation technique combined with a common-path interferometer and lithographically fabricated individual gold nanoantennas, we experimentally determine the scattering and absorption cross-section spectra of different optical antennas simultaneously and quantitatively for the first time. PMID:23368203

Husnik, Martin; Linden, Stefan; Diehl, Richard; Niegemann, Jens; Busch, Kurt; Wegener, Martin

2012-12-01

378

Global comparisons of earthquake source spectra  

NASA Astrophysics Data System (ADS)

A key question in earthquake seismology is whether earthquake sources in different tectonic regions are functionally equivalent in terms of radiated ground motion. This thesis compares the apparent earthquake source radiation for six different tectonic regions covering Japan, Mexico, Turkey, California, British Columbia (B.C., western Canada), and eastern North America (ENA). The source, path and site effects were systematically separated from the observed spectra to the extent possible, to allow interregional comparisons of apparent source radiation. Large Fourier spectra databases were developed for both horizontal and vertical components over all distances for earthquakes of magnitude 2.5 to 7.5. Regional parameters characterizing source, path, and site properties, including crustal and near-surface site amplifications, were thoroughly investigated to separate the corresponding spectral responses, and thereby isolate apparent source processes. Effects on observed spectra of geometrical spreading, regional anelastic scattering, crustal and site amplification and deamplifications were removed to obtain the source spectra. Empirical source models were described at discrete frequencies as functions of m1 for each study region. Vertical spectra are more closely related to, and diagnostic of, the apparent source radiation than are horizontal spectra. Further study on source spectral scaling should take the source mechanism into account. After all the corrections made in this study, any discrepancies in source spectra between regions may be related to faulting mechanism. Source mechanism appears to be an important remaining influential factor that has not been sufficiently investigated at the present time. This is supported by the recent experimental findings that faulting types and shearing modes could have at least affected the spectral levels, if not the shape. The maximum slip velocity, num ? 0.5 m/s, estimated from the regional high frequency levels of the spectra, provides a region-independent source parameter that is more meaningful than the Brune stress parameter. (Abstract shortened by UMI.)

Chen, Shengzao

379

Optical spectra, energy levels, and crystal-field analysis of tripositive rare-earth ions in Y2O3. II. Non-Kramers ions in C2 sites  

Microsoft Academic Search

Optical absorption and fluorescence spectra of the non-Kramers ions Pr3+, Tb3+, and Ho3+ in the C2 sites of Y2O3 are reported. A crystal-field analysis of these data and previously reported data for Eu3+ and Tm3+ is performed that is based on a Hamiltonian of C2 point-group symmetry, including J-mixing effects. A best-fit analysis is performed for all five ions; resulting

Richard P. Leavitt; John B. Gruber; N. C. Chang; Clyde A. Morrison

1982-01-01

380

Electromagnetic unit fuel injector  

SciTech Connect

This patent describes an electromagnetic unit fuel injector of the type including a housing havine a pump cylinder therein; an externally actuated plunger reciprocable in the cylinder means to define therewith a pump chamber. The housing includes a valve body having a spray outlet at one end thereof for the discharge of fuel. An injection valve is movable in the valve body to control flow through the spray outlet. An inlet passage is in flow communication with the pump chamber and is connectable at its other end to a source of fuel. A pressure modulated servo chamber is in the housing. A spring means and a servo piston means operatively connected to the injection valve with the servo piston means being positioned so as to be acted on by the pressure of fuel in the servo chamber and a discharge passage in the housing connects the pump chamber to the spray outlet and to the servo chamber and has a throttle orifice controlling fuel flow to the servo chamber. The housing means further includes a drain passage means in flow communication at one end with the servo chamber and at its opposite end with a source of fuel at a predetermined pressure and a pressure sensitive control valve operatively positioned in the housing. A pull type solenoid is operatively supported in the housing means and a fuel passage means connectable is at one end to a source of fuel at a suitable supply pressure and at its other end being in operative flow communication with the pump chamber. The improvement wherein the control valve is in the form of a poppet valve and wherein the stepped bore includes an enlarged internal diameter portion next adjacent to the valve seat whereby the pressure of fuel in the annulus cavity can act against the head in a valve opening direction and wherein the force of the valve return spring is preselected so that the control valve is also operative as a pressure relief valve.

Deckard, J.I.

1986-02-25

381

Novel electromagnetic micropump  

NASA Astrophysics Data System (ADS)

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.

Feldmann, M.; Demming, S.; Lesche, C.; Büttgenbach, S.

2007-12-01

382

Electron transitions and the spectrum of radiation emitted by an atom interacting with an ultrashort electromagnetic pulse  

Microsoft Academic Search

Electron transitions and the spectrum of radiation emitted by an atom interacting with an ultrashort electromagnetic pulse\\u000a are studied based on the sudden perturbation approximation. The excitation and ionization probabilities, the spectra of pulse\\u000a reradiation by the atom, and the reradiation cross sections are calculated. It is concluded that the reradiation of ultrashort\\u000a electromagnetic pulses by multielectron atoms is of

V. I. Matveev

2003-01-01

383

78 FR 33633 - Human Exposure to Radiofrequency Electromagnetic Fields  

Federal Register 2010, 2011, 2012, 2013

...Exposure to Radiofrequency Electromagnetic Fields; Reassessment of Exposure to Radiofrequency Electromagnetic Fields Limits and Policies; Final...Exposure to Radiofrequency Electromagnetic Fields AGENCY: Federal...

2013-06-04

384

High performance electromagnetic simulation tools  

NASA Astrophysics Data System (ADS)

Army Research Office Grant #DAAH04-93-G-0453 has supported the purchase of 24 additional compute nodes that were installed in the Intel iPsC/860 hypercube at the Univesity Of Kentucky (UK), rendering a 32-node multiprocessor. This facility has allowed the investigators to explore and extend the boundaries of electromagnetic simulation for important areas of defense concerns including microwave monolithic integrated circuit (MMIC) design/analysis and electromagnetic materials research and development. The iPSC/860 has also provided an ideal platform for MMIC circuit simulations. A number of parallel methods based on direct time-domain solutions of Maxwell's equations have been developed on the iPSC/860, including a parallel finite-difference time-domain (FDTD) algorithm, and a parallel planar generalized Yee-algorithm (PGY). The iPSC/860 has also provided an ideal platform on which to develop a 'virtual laboratory' to numerically analyze, scientifically study and develop new types of materials with beneficial electromagnetic properties. These materials simulations are capable of assembling hundreds of microscopic inclusions from which an electromagnetic full-wave solution will be obtained in toto. This powerful simulation tool has enabled research of the full-wave analysis of complex multicomponent MMIC devices and the electromagnetic properties of many types of materials to be performed numerically rather than strictly in the laboratory.

Gedney, Stephen D.; Whites, Keith W.

1994-10-01

385

Activity: Graphing Spectra  

NSDL National Science Digital Library

This activity introduces two different representations of spectra: the photographic representation, such as the rainbow, and the graphical representation used more often by astronomers. A rainbow is often given as an everyday example of a spectrum. Most students have seen a rainbow, so this example is used to help make the unfamiliar more familiar. However, the spectra that scientists use, which students will see in this lesson plan, appear very different than a rainbow. In this activity, students will explore for themselves two different representations of the same spectrum, noting advantages and disadvantages of each. They will explore the differences and similarities of both these representations, and will develop a more intuitive feel for a graphical representation, which may not yet be familiar to them.

386

Electromagnetic diode based on nonlinear electromagnetically induced transparency in metamaterials  

NASA Astrophysics Data System (ADS)

We propose a scheme for subwavelength electromagnetic diode by employing the nonreciprocal electromagnetically induced transparency (EIT) in metamaterials. One-way response, with 17.36 dB transmission contrast and -4.4 dBm operating power, is conceptually demonstrated in a microwave waveguide system with asymmetric absorption and a varactor as the nonlinear medium inclusion. Such low-threshold and high-contrast transmission diode action comes from the EIT mechanism, which possesses narrower and sharper features than the Lorentz resonance. This mechanism will be useful for all-optical signal processing with advanced materials.

Sun, Yong; Tong, Yuan-wei; Xue, Chun-hua; Ding, Ya-qiong; Li, Yun-hui; Jiang, Haitao; Chen, Hong

2013-08-01

387

Possible Ionospheric Electromagnetic Perturbations Induced by the Ms7.1 Yushu Earthquake  

NASA Astrophysics Data System (ADS)

The power spectrum density (PSD) of magnetic field in the ELF/VLF band recorded by the experiment IMSC onboard the DEMETER satellite were used to study the Ms7.1 Yushu earthquake taking place on April 13, 2010 in China. The results indicate that possible ionospheric electromagnetic perturbations occurring 4 days before the earthquake in the frequency range [370-897 Hz]. Along the orbit 30880_up, which passed over the epicenter area on 9 April, enhanced PSD value of magnetic field at 410 Hz was detected both over the epicentral area and its conjugate point in the southern hemisphere. While on revisited orbits during other days (before and after the earthquake) the magnetic field spectra remained at a relatively low level. In order to be sure that the electromagnetic disturbances were induced by this Yushu earthquake, relative variations of the magnetic field in the ELF/VLF range [370-897 Hz] were calculated and compared with the normal background during 3 years (2007, 2008 and 2009) in the time interval from Jan. 1st to Apr. 30 and in the area [23°N-43°N, 86°E-106°E]. The results show that the normal level of magnetic field in this area is relatively low (~10-7 nT2/Hz), but a large increase occurred from Apr. 1st to Apr. 14 which exceeds 5?b. After the earthquake, the magnetic field in the ELF/VLF range gradually decreased. In order to exclude the influence of geomagnetic field activity, we selected only the data recorded during magnetically quiet local night-times. In addition, artificial noises were also removed from the dataset used in the present paper. Therefore the observed perturbations were independent of geomagnetic field disturbances, and might be attributed to seismic activity.

Zhima, Zeren; Xuhui, Shen; Xuemin, Zhang; Jinbin, Cao; Jianping, Huang; Xinyan, Ouyang; Jing, Liu; Lu, Bingqing

2012-06-01

388

Binary black holes' effects on electromagnetic fields.  

PubMed

In addition to producing 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 here 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 a possible 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. PMID:19792706

Palenzuela, Carlos; Anderson, Matthew; Lehner, Luis; Liebling, Steven L; Neilsen, David

2009-08-21

389

Electromagnetic fields: the jury's still out. 2. Societal reverberations  

Microsoft Academic Search

The debate over setting standards for exposure to power-frequency electromagnetic fields when science has not yet determined what levels, if any, are dangerous is examined. Regulatory agencies, standards bodies and utilities are struggling to make policy in the face of two opposing views: one camp believes the evidence of health effects is enough to warrant precautionary action to limit exposure,

K. Fitzgerald

1990-01-01

390

Introduction to Eye-Opening Technology: The Electromagnetic Spectrum.  

ERIC Educational Resources Information Center

Provides classroom activities centered around how the electromagnetic spectrum yields vital insights about the evolution of the universe. Activities targeted for grade levels 6-12 illustrate the importance of light and color in space exploration. Includes a poster. (Author/SOE)

Smith, Denise; Eisenhamer, Bonnie; DeVore, Edna; Bianchi, Luciana

2003-01-01

391

Teaching electromagnetic fields and FEM for undergraduate students  

Microsoft Academic Search

An approach to the finite element method applied to the solution of electromagnetic fields problems is presented. This methodology is suitable for teaching electrical engineering students at undergraduate level, because the problem formulation is based solely on the direct integration of Maxwell's equations and the approach is only valid for first-order elements, thereby avoiding the use of an excessively complex

L. Lebensztajn; V. S. Silva; L. N. Rossi; J. R. Cardoso

2001-01-01

392

Electromagnetic field generation by ATP-induced reverse electron transfer  

Microsoft Academic Search

This paper describes a mechanism to explain low-level light emission in biology. A biological analog of the electrical circuitry, modeled on the parallel plate capacitor, traversed by a helical structure, required to generate electromagnetic radiation in the optical spectral range, is described. The charge carrier required for the emissions is determined to be an accelerating electron driven by an ATP-induced

Richard H. Steele

2003-01-01

393

Electromagnetic response of a vortex in layered superconductors  

Microsoft Academic Search

We calculate the response of a vortex core in a layered superconductor to an ac electromagnetic field. In particular we investigate the intermediate clean regime, where the broadening of the vortex core bound states is comparable to or larger than the level spacing. The response of the order parameter, impurity self-energy, and currents are obtained by a self-consistent determination of

Matthias Eschrig; J. A. Sauls; D. Rainer

1999-01-01

394

Nonionizing electromagnetic wave effects in biological materials and systems  

Microsoft Academic Search

Electromagnetic waves from the lower radio frequencies up through the optical spectrum can generate a myriad of effects and responses in biological specimens. Some of these effects can be harmful to man at high radiation intensities, producing burns, cataracts, chemical changes, etc. Biological effects have been reported at lower radiation intensities, but it is not now known if low-level effects

C. C. Johnson; A. W. Guy

1972-01-01

395

The Numerical Electromagnetics Code (NEC) - a brief history  

Microsoft Academic Search

The Numerical Electromagnetics Code, NEC as it is commonly known, continues to be one of the more widely used antenna modeling codes in existence. With several versions in use that reflect different levels of capability and availability, there are now 450 copies of NEC4 and 250 copies of NEC3 that have been distributed by Lawrence Livermore National Laboratory to a

G. J. Burke; E. K. Miller; A. J. Poggio

2004-01-01

396

CMOS OpAmp Resisting to Large Electromagnetic Interferences  

Microsoft Academic Search

A CMOS operational amplifier with high immunity to electromagnetic interferences is presented. It is based on an easy modification of the differential pair with active current load. The proposed input stage can be fabricated in standard CMOS technologies, and it neither requires extra mask levels, such as triple well, nor external components. Analysis and results are provided for very large

Anna Richelli

2010-01-01

397

METHODOLOGICAL NOTES: Superluminal electromagnetic solitons in nonequilibrium media  

Microsoft Academic Search

The possibility of stable faster-than-light propagation of ultimately short (without high-frequency carrier) electromagnetic solitons, breathers, and nonresonant envelope solitons is discussed based on the simple model of two-component nonequilibrium media undergoing two-level quantum transitions with widely differing eigenfrequencies.

Sergei V. Sazonov

2001-01-01

398

FOREWORD: Special section on electromagnetic characterization of buried obstacles  

Microsoft Academic Search

This Inverse Problems special section on electromagnetic characterization of buried obstacles contains a selection of 14 invited papers, involving 41 authors and 19 research groups worldwide. (Though this section consists of invited papers, the standard refereeing procedures of Inverse Problems have been rigorously observed.) We do not claim to have reached all the high-level researchers in the field, but we

Dominique Lesselier; Weng Cho Chew

2004-01-01

399

Auroral Colors and Spectra  

NSDL National Science Digital Library

This site, co-produced by the NCAR High Altitude Observatory and the COMET Program, provides an explanation of how auroral colors are produced. The emission of specific colors of light is discussed in relation to oxygen and nitrogen emission spectra. Numerous images, graphs, and a video of an aurora are included. The site is part of "Physics of the Aurora: Earth Systems," an interactive learning module about the aurora.

2007-01-26

400

Martian neutron leakage spectra  

NASA Astrophysics Data System (ADS)

A high-energy nucleon-meson transport code is used to calculate energy spectra of Martian leakage neutrons. Four calculations are used to simulate a uniform surface layer containing various amounts of water, different burial depths of a 50 percent water layer underneath a 1 percent water layer, changing atmospheric pressure, and a thick carbon dioxide ice sheet overlying a "dirty" water ice sheet. Calculated spectra at energies less than about 1000 eV were fitted by a superposition of thermal and epithermal functions having four free parameters, two of which (thermal and epithermal amplitudes) were found to vary systematically and to specify uniquely the configuration in each of the series. Parameter variations depend on the composition of the assumed surface layers through the average atomic mass and the macroscopic scattering and absorption cross sections. It is concluded that measurements of leakage neutron spectra should allow determination of the hydrogen content of surface layers buried to depths up to about 100 g/sq. cm and determination of the thickness of a polar dry ice cap up to a thickness of about 250 g/sq. cm.

Drake, D. M.; Feldman, W. C.; Jakosky, B. M.

1988-06-01

401

Effects of noise and electromagnetic fields on reproductive outcomes.  

PubMed Central

Much public health research has been directed to studies of cancer risks due to chemical agents. Recently, increasing attention has been given to adverse reproductive outcomes as another, shorter-term biologic indicator of public health impact. Further, several low-level ubiquitous physical agents have been implicated recently as possibly affecting human health. These physical factors (noise and electromagnetic fields) represent difficult topics for research with epidemiologic study methods. This paper provides a brief review of the published data related to the risk of adverse reproductive outcomes and exposure to noise or electromagnetic fields. The discussion includes ideas for possible biologic mechanisms, considerations for exposure assessment, and suggestions for epidemiologic research.

Meyer, R E; Aldrich, T E; Easterly, C E

1989-01-01

402

Electromagnetic jets from compact objects  

NASA Technical Reports Server (NTRS)

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.

Michel, F. Curtis

1987-01-01

403

Un-renormalized classical electromagnetism  

SciTech Connect

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.

Ibison, Michael [Institute for Advanced Studies at Austin, 4030 West Braker Lane, Suite 300, Austin, TX 78759 (United States)]. E-mail: ibison@earthtech.org

2006-02-15

404

Synthetic spectra of CP stars compared with UVES spectra  

NASA Astrophysics Data System (ADS)

Results from spectral analyses of some HgMn stars observed with UVES at high resolution and high S/N are available on-line in the form of plots showing superimposed observed and LTE-computed spectra. The material is available on line at http://wwwuser.oat.ts.astro.it/castelli/stars.html. The ranges studied are divided into 6Å wide intervals. The plots have identifications, excitation potential of the lower level, and predicted line intensities written above the lines. Complete analyses covering the 3050 - 9500Å region have been performed for two stars, HD175640 and HR6000. The on-line plots show the quality of the agreement between observations and computations and can be used as a template for other stars of the same spectral type. For instance, HD175640 and HR6000 are excellent examples of a very overabundant Mn ([+2.4]) star and of a very overabundant Fe ([+0.7]) star, respectively.

Castelli, F.; Hubrig, S.

2008-04-01

405

Active System for Electromagnetic Perturbation Monitoring in Vehicles  

NASA Astrophysics Data System (ADS)

Nowadays electromagnetic environment is rapidly expanding in frequency domain and wireless services extend in terms of covered area. European electromagnetic compatibility regulations refer to limit values regarding emissions, as well as procedures for determining susceptibility of the vehicle. Approval procedure for a series of cars is based on determining emissions/immunity level for a few vehicles picked randomly from the entire series, supposing that entire vehicle series is compliant. During immunity assessment, the vehicle is not subjected to real perturbation sources, but exposed to electric/magnetic fields generated by laboratory equipment. Since current approach takes into account only partially real situation regarding perturbation sources, this paper proposes an active system for determining electromagnetic parameters of vehicle's environment, that implements a logical diagram for measurement, satisfying the imposed requirements. This new and original solution is useful for EMC assessment of hybrid and electrical vehicles.

Matoi, Adrian Marian; Helerea, Elena

406

Gauge invariant fractional electromagnetic fields  

NASA Astrophysics Data System (ADS)

Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators.

Lazo, Matheus Jatkoske

2011-09-01

407

Time reversal of electromagnetic waves.  

PubMed

We report the first experimental demonstration of time-reversal focusing with electromagnetic waves. An antenna transmits a 1-micros electromagnetic pulse at a central frequency of 2.45 GHz in a high-Q cavity. Another antenna records the strongly reverberated signal. The time-reversed wave is built and transmitted back by the same antenna acting now as a time-reversal mirror. The wave is found to converge to its initial source and is compressed in time. The quality of focusing is determined by the frequency bandwidth and the spectral correlations of the field within the cavity. PMID:15169405

Lerosey, G; de Rosny, J; Tourin, A; Derode, A; Montaldo, G; Fink, M

2004-05-14

408

Electromagnetic Models of Extragalactic Jets  

SciTech Connect

Relativistic jets may be confined by large-scale, anisotropic electromagnetic stresses that balance isotropic particle pressure and disordered magnetic field. A class of axisymmetric equilibrium jet models will be described and their radiative properties outlined under simple assumptions. The partition of the jet power between electromagnetic and mechanical forms and the comoving energy density between particles and magnetic field will be discussed. Current carrying jets may be recognized by their polarization patterns. Progress and prospects for measuring this using VLBI and GLAST observations will be summarized.

Lisanti, M.; Blandford, R.; /KIPAC, Menlo Park

2007-10-22

409

Electromagnetic Gun With Commutated Coils  

NASA Technical Reports Server (NTRS)

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.

Elliott, David G.

1991-01-01

410

Electromagnetic interference in critical care.  

PubMed

Mobile communication and wireless data transmission are playing an increasing role in health care. Reports describing medical device malfunction related to cellular phones have raised awareness about the problem of electromagnetic interference. Although initial institutional responses were to ban cellular devices in hospitals, these restrictions are relaxing as the knowledge base in this area expands. Medical device malfunction is extremely rare if the distance from the transmitting device is greater than 1 m. This article reviews the current understanding of electromagnetic interference as it applies to the technology-rich critical care environment. PMID:16990096

Lapinsky, Stephen E; Easty, Anthony C

2006-09-01

411

Liquid phase effects on benzene UV spectra  

NASA Astrophysics Data System (ADS)

Some results for the benzene molecular properties in liquid phase are shown, stressing the interest on the electronic spectra properties. The way we follow to perform calculations is a Semi-classical one. taking into account the structural information of the benzene pure liquid and the electronic structure of the benzene molecule at the CNDO level.

Se?e, L. M.; Botella, V.; Gómez, P. C.; Fernández, M.

1986-03-01

412

Background noise spectra of global seismic stations  

SciTech Connect

Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

Wada, M.M.; Claassen, J.P.

1996-08-01

413

In-Line, Concurrent Electromagnetic Beam Analyzer.  

National Technical Information Service (NTIS)

This invention relates generally to electromagnetic radiation technology and more specifically to electromagnetic beam diagnostics. An in-line concurrent diagnostic analyzer for laser beams is described. An aperture mirror splits the initial laser beam in...

F. Mako J. A. Pasour

1984-01-01

414

Parametric Instabilities of Electromagnetic Waves in Plasmas.  

National Technical Information Service (NTIS)

A simple formalism for the parametric decay of an intense, coherent electromagnetic wave into an electrostatic wave and scattered electromagnetic waves in a homogeneous plasma is developed. Various instabilities including Brillouin and Raman backscatterin...

J. F. Drake P. K. Kaw Y. C. Lee G. Schmidt C. S. Liu

1973-01-01

415

Hybrid Techniques for Complex Aerospace Electromagnetics Problems.  

National Technical Information Service (NTIS)

Important aerospace electromagnetics problems include the evaluation of antenna performance on aircraft and the prediction and control of the aircraft's electromagnetic signature. Due to the ever increasing complexity and expense of aircraft design, aeros...

J. Aberle

1993-01-01

416

Electromagnetic Gage Techniques for Dynamic Tensile Fracture.  

National Technical Information Service (NTIS)

Electromagnetic gage techniques are ideally suited to measuring in-material motions during the dynamic fracture of many materials. As electromagnetic sensing elements can be constructed of any conducting material and are not affected by micro-deformation ...

C. Young

1988-01-01

417

Electromagnetic Compatibility of Nuclear Power Plants.  

National Technical Information Service (NTIS)

Lately, there has been a mounting concern about the electromagnetic compatibility of nuclear-power-plant systems mainly because of the effects due to the nuclear electromagnetic pulse, and also because of the introduction of more-sophisticated and, theref...

H. S. Cabayan

1983-01-01

418

Methodology for Selecting an Electromagnetic Gun System.  

National Technical Information Service (NTIS)

This thesis proposes a methodology for selecting an electromagnetic launcher (EML) based upon mission requirements and available technology. The intent of the study is twofold. First, it reviews electromagnetic launcher applications, the principles of ele...

K. E. Reinhard

1992-01-01

419

Development of a Strong Electromagnet Wiggler.  

National Technical Information Service (NTIS)

The Strong Electromagnet (SEM) wiggler is a permanent magnet-assisted electromagnet under development at the Lawrence Livermore National Laboratory (LLNL) as part of the Induction Linac Free-Electron-Laser (IFEL) program. This concept uses permanent magne...

M. J. Burns G. A. Deis R. H. Holmes R. D. Van Maren K. Halbach

1987-01-01

420

3D Electromagnetic Field Analysis for Mixing Suspension Electromagnet Used by Maglev Train  

Microsoft Academic Search

A maglev train is supported by electromagnetic force between suspension electromagnet and track and is driven by linear motor. The suspension electromagnet is an important part of a maglev train. Its operating characteristic has a direct bearing on technology-economy performance and run safety of the whole train. The paper advances a new electromagnet structure mixing permanent magnet with electric excitation

Liu Shaoke; Guo Zhongjun; Chen Guirong

2010-01-01

421

[Raman spectra of pyroxene].  

PubMed

By testing the Raman spectra of megacryst pyroxene, enstatite and diopside in terms of location, shape and intensity, the symmetries of the main spectral band of pyroxene and the vibration modes of Raman shift were identified. The spectral bands of corresponding ionic groups such as non-bridge oxygen Si-O- and bridge oxygen Si-O0, O-Si-O and M-O were assigned for vibrational mode. Through the change in the intensity of the spectral band in different section direction and the deficiency of some spectral bands, the orientation problem in mineral crystallography was preliminarily studied. PMID:20384128

Wang, Rong; Zhang, Bao-Min

2010-02-01

422

Electromagnetically induced transparency for a double Fano-profile system  

NASA Astrophysics Data System (ADS)

A ?-like model of atomic levels involving two auto-ionizing states is considered. The levels are irradiated by two external electromagnetic fields, a strong driving and a weak probing ones. The analytical formula for medium susceptibility shows an additional electromagnetically induced transparency window caused by the second auto-ionizing level. Characteristics of both transparency windows are analyzed depending on parameters of auto-ionizing levels and the external driving field. Manipulation of these characteristics seems to be very effective because of their large sensitivity with respect to the parameters involved in the problem. This manipulation becomes even more feasible when considered model is implemented in so-called laser-induced continuum structure.

Bui Dinh, Thuan; Cao Long, Van; Leo?ski, Wies?aw; Pe?ina, Jan

2014-06-01

423

Interference spectra transformation of counter-propagating pulses propagating through a dielectric slab  

NASA Astrophysics Data System (ADS)

A phenomenon of spectra transformation of counter-propagating electromagnetic pulses which propagate through a dielectric slab is studied. The spectra transformation occurs due to the interference energy flux which exists during the propagation of pulses through a slab. The physical conditions (time matching, amplitude matching and existence of the slab critical size) under which the maximal interference energy flux is observed are discussed. It is found that the interference energy flux modulates the spectra of the initial signals and transfers energy through the slab unequally at different frequencies. The energy transfer does not occur at multiple frequencies which correspond to the reflectionless passage of monochromatic waves through the slab.

Kochetov, Bogdan A.

2014-07-01

424

Injuries from Electromagnetic Energy  

Microsoft Academic Search

Injury occurs when body tissues are subjected to levels of energy outside the normal tolerance bands. Excessive energy damages tissues, potentially beyond repair, and disrupts normal physiologic functioning. Injury may also occur when inadequate energy is available, such as extreme cold leading to frostbite injury, or disruption of normal cellular energy systems such as asphyxiation. Energy may be in the

STEPHEN A. MCCURDY

425

Theoretical Studies of Molecular Spectra  

NASA Technical Reports Server (NTRS)

This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

McKay, Christopher (Technical Monitor); Freedman, Richard S.

2002-01-01

426

Open tools for electromagnetic simulation programs  

Microsoft Academic Search

Purpose – The aim of the paper is to propose three computer tools to create electromagnetic simulation programs: GiD, Kratos and EMANT. Design\\/methodology\\/approach – The paper presents a review of numerical methods for solving electromagnetic problems and presentation of the main features of GiD, Kratos and EMANT. Findings – The paper provides information about three computer tools to create electromagnetic

Javier Mora; Rubén Otín; Pooyan Dadvand; Enrique Escolano; Miguel A. Pasenau; Eugenio Oñate

2006-01-01

427

Three-phase electromagnetic AC motors  

Microsoft Academic Search

Advanced three-phase electromagnetic ac motors based on electromagnetic gate-inductor motors are proposed. The concept of\\u000a development and the constructive scheme of a three-phase electromagnetic ac motor are given. Advantages of the proposed motors\\u000a compared to asynchronous motors are shown.

Yu. V. Smirnov

2009-01-01

428

The Future of Electromagnetic Field Litigation  

Microsoft Academic Search

This Article explores the dynamics and complexity of the electromagnetic field controversy. Presently, there are many unanswered questions with respect to the effects electromagnetic radiation has on people who live or work near power lines. This Article examines the state of domestic and international scientific evidence that exists regarding the risks of electromagnetic radiation. Ultimately, the Article concludes that although

Michael C. Anibogu

1998-01-01

429

Noninvasive valve monitor using alternating electromagnetic field  

Microsoft Academic Search

One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic

D. M. Eissenberg; H. D. Haynes; D. A. Casada

1993-01-01

430

Some Student Conceptions of Electromagnetic Induction  

ERIC Educational Resources Information Center

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…

Thong, Wai Meng; Gunstone, Richard

2008-01-01

431

Electromagnetic Scattering by Charged Dust Aggregates  

Microsoft Academic Search

Dust aggregates in plasma charge, which makes it difficult to study the propagation of electromagnetic wave in it. While in order to study the influence of charged dust to the space detection, some work must be done for the electromagnetic characteristic of it. Based on discrete dipole approximation (DDA), electromagnetic scattering characteristic of charged dust aggregates is studied. At the

Haiying Li; Zhensen Wu; Guangchi Wang

2006-01-01

432

Parallelisation of electromagnetic simulation codes  

Microsoft Academic Search

In this paper results obtained from the parallelisation of existing 3D electromagnetic Finite Element codes within the ESPRIT HPCN project PARTEL are presented. The parallelisation procedure, based on the Bulk Synchronous Parallel approach, is outlined and the encouraging results obtained in terms of speed-up on some industrially significant test cases are described and discussed

R. Janssen; M. Dracopoulos; K. Parrott; E. Slessor; P. Alotto; P. Molfino; M. Nervi; J. Simkin

1998-01-01

433

Experimental electromagnetic launchers at MRL  

Microsoft Academic Search

The design and construction of small caliber rail-type electromagnetic launchers are described. Bore sizes of 48 sq mm or 100 sq mm cross section are used and barrel lengths vary from 200 mm to 2 m. Sufficient information is provided to reproduce any of the devices, all of which are proving to be very useful experimentally. Examples of results are

A. J. Bedford; G. A. Clark; Y. C. Thio

1983-01-01

434

Electromagnetic Mass Difference of Kaons.  

National Technical Information Service (NTIS)

Using the algebra of currents, modified Weinberg sum rules, and the tadpole model of Coleman, Glashow, and Schnitzer, a calculation is made of the kaon electromagnetic mass difference in the soft-kaon limit to be -3.9 plus or minus 0.6 MeV, in excellent a...

C. L. Cook L. E. Evans M. Y. Han N. R. Lipshutz N. Straumann

1968-01-01

435

Technology-based electromagnetic education  

Microsoft Academic Search

In this paper, we briefly review the various roles of technology in stimulating interest and deepening understanding of abstract and highly mathematical subjects such as electromagnetics (EM). The general advantages of using technology in offering Web-based courses and professional training are described and examples of the ongoing activities in this area are summarized. Focus, however, is placed on the development

Magdy F. Iskander

2002-01-01

436

GROUND AND AIRBORNE ELECTROMAGNETIC METHODS  

Microsoft Academic Search

1. SUMMARY Electromagnetic (EM) methods are used to map variations in electrical properties. The main physical property involved in these methods is inductive electrical conductivity, which is a measure of how easily electrical current can pass through a material. Conductivity is a complex function of several variables including the conductivity of solid materials, conductivity of pore fluids, porosity, arrangement of

437

Electromagnetic fields and public health  

Microsoft Academic Search

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,

T. E. Aldrich; C. E. Easterly

1987-01-01

438

Gravitational Analog of the Electromagnetic  

Microsoft Academic Search

The gravitational analog of the electromagnetic Poynting vector is constructed us- ing the field equations of general relativity in the Hilbert gauge. It is found that when the gravitational Poynting vector is applied to the solution of the linear mass quadrupole oscillator, the correct gravitational quadrupole radiation flux is ob- tained. Further to this, the Maxwell-like gravitational Poynting vector gives

Poynting Vector

439

Electromagnetic Interaction of Dual Systems  

Microsoft Academic Search

We introduce the electromagnetic interaction of dual models by means of a generalized minimum-interaction principle. It leads to a conserved current and a gauge-invariant theory. Unfortunately, the strong gauge conditions are preserved only for on-mass-shell photons, which leads to unphysical poles in k.k'.

P. Ramond

1972-01-01

440

Analysis of Units in Electromagnetism.  

National Technical Information Service (NTIS)

To define a system of electromagnetic units uniquely, six basic quantities must be chosen. Maxwell's equations are derived in a general form, independent of any particular choice of the six basic quantities. It is shown that the MKSA-formulation of the fi...

F. Primdahl

1971-01-01

441

Electromagnetic response of unconventional superconductors  

Microsoft Academic Search

We derive the current response to the linearly polarized electromagnetic field incident normally on the specular surface of a clean nonconventional superconductor with orbital spontaneous magnetization parallel to the crystal axis and perpendicular to the crystal surface. The result includes the usual part known from the theory of conventional superconductivity, as well as the magneto-optical term typical for superconductors with

V. P. Mineev

2008-01-01

442

Electromagnetic vortices in a plasma  

Microsoft Academic Search

It is shown that electromagnetic solitary vortices (with a nonpotential electric field) can exist in a plasma. Vortices of two types are discussed: Alfven and ballooning. An Alfven vortex can exist in a homogeneous plasma immersed in a homogeneous magnetic field. A ballooning vortex is predicted for a plasma with homogeneous density immersed in crossed magnetic and gravitational fields.

G. D. Aburdzhaniia; A. B. Mikhailovskii; O. G. Onishchenko; S. E. Sharapov; A. P. Churikov

1984-01-01

443

Proposed electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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.

Bailey, R. L.

1973-01-01

444

Finite formulation of electromagnetic field  

Microsoft Academic Search

We show that the equations of electromagnetism can be directly obtained in a finite form, i.e., discrete, thus avoiding the traditional discretization methods of Maxwell's differential equations. The finite formulation can be used with unstructured meshes in two and three dimensions and easily permits to obtain fourth-order convergence

Enzo Tonti; Piazzale Europa

2002-01-01

445

Explanations, Education, and Electromagnetic Fields.  

ERIC Educational Resources Information Center

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…

Friedman, Sharon M.

446

Electromagnetic Levitation of a Disc  

ERIC Educational Resources Information Center

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…

Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

2012-01-01

447

Coupling Electromagnetism to Global Charge  

NASA Astrophysics Data System (ADS)

It is shown that an alternative to the standard scalar quantum electrodynamics (QED) is possible. In this new version, there is only global gauge invariance as far as the charged scalar fields are concerned, although local gauge invariance is kept for the electromagnetic field. The electromagnetic coupling has the form j?(A? +??B) where B is an auxiliary field and the current j? is A? independent, so that no "sea gull terms" are introduced. As a consequence of the absence of sea gulls, it is seen that no Klein paradox appears in the presence of a strong square well potential. In a model of this kind, spontaneous breaking of symmetry does not lead to photon mass generation, instead the Goldstone boson becomes a massless source for the electromagnetic field. When spontaneous symmetry breaking takes place infrared questions concerning the theory and generalizations to global vector QED are discussed. In this framework, Q-Balls and other nontopological solitons that owe their existence to a global U(1) symmetry can be coupled to electromagnetism and could represent multiply charged particles now in search in the large hadron collider (LHC). Furthermore, we give an example where an "Emergent" Global Scalar QED can appear from an axion-photon system in an external magnetic field. Finally, formulations of Global Scalar QED that allow perturbative expansions without sea gulls are developed.

Guendelman, E. I.

2013-12-01

448

Electromagnetic electron temperature anisotropy instabilities  

NASA Technical Reports Server (NTRS)

This paper considers electromagnetic Vlasov instabilities driven by electron temperature anisotropies in a homogeneous, nonrelativistic magnetized plasma. Numerical solutions of the full linear dispersion equation for bi-Maxwellian distribution functions and instabilities propagating parallel to the magnetic field are presented. Parametric dependences of the maximum growth rates of the electron fire hose and whistler anisotropy instabilities are given.

Gary, S. P.; Madland, C. D.

1985-01-01

449

Therapeutic applications of electromagnetic power  

Microsoft Academic Search

The use of electromagnetic (EM) power for therapeutic applications has existed since EM sources have been available to man. Physical medicine has been a major user of both shortwave (27.33 MHz) and microwave (2450 MHz) diathermy over the decades in which the EM power has been used to heat deep tissues for stimulating various medically beneficial physiologic responses in the

ARTHUR W. GUY; JUSTUS F. LEHMANN; JERRY B. STONEBRIDGE

1974-01-01

450

Electromagnetic hypersensitivity: Fact or Fiction?  

Microsoft Academic Search

As the prevalence of wireless telecommunication escalates throughout the world, health professionals are faced with the challenge of patients who report symptoms they claim are connected with exposure to some frequencies of electromagnetic radiation (EMR). Some scientists and clinicians acknowledge the phenomenon of hypersensitivity to EMR resulting from common exposures such as wireless systems and electrical devices in the home

Stephen J. Genuis; Chris Lipp

451

Millimeter wave electromagnetic measurement techniques  

Microsoft Academic Search

This report presents the results of studies to develop the rationale for electromagnetic measurement techniques for use in the EMC evaluation of millimeter wave (MMW) communication-electronic equipment and systems. In the development of this rationale, seven basic tasks were performed. Under the first task, the EMC\\/EMI data requirements for MMW equipments and systems were established to provide a clear definition

E. E. Donaldson; J. C. Mantovani; G. B. Melson; D. W. Acree

1982-01-01

452

Computational design for electromagnetic simulations  

NASA Astrophysics Data System (ADS)

An automatic computational procedure has been developed to efficiently and accurately design the shape of complicated electromagnetic objects. These electromagnetic objects can be simulated for operation at high frequencies (˜10 GHz), and can be comprised of dissimilar materials. The automated design procedure consists of linking together an original electromagnetic field simulation tool, an original adjoint routine for obtaining sensitivity derivatives, and an original grid-smoothing tool with an existing optimization package. The electromagnetic field simulation software employs a temporally and spatially higher-order accurate Streamline Upwind/Petrov-Galerkin finite-element method that numerically solves Maxwell's equations in the time domain using implicit time stepping. The software for computing sensitivity derivatives employs a reverse-mode time-accurate discrete adjoint methodology that is formulated to automatically maintain consistency with the electromagnetic field simulation software. Grid smoothing is achieved using a spatially higher-order accurate Galerkin finite-element method that generates a numerical solution to the linear elastic equations. All computational solutions to the linear systems present in each software tool are obtained using the Generalized Minimum Residual algorithm with block diagonal preconditioning. Each software tool is implemented using a parallel processing paradigm and is therefore capable of being executed on a distributed memory supercomputer. The order of accuracy of the electromagnetic field simulation software has been determined by using comparisons with exact solutions. The field software's results were compared to the exact solution of a rectangular resonant cavity. In all cases, the order properties of the field software exceed theoretical expectations when linear, quadratic, and cubic tetrahedral elements are employed to discretize the field. To demonstrate the consistency of the adjoint-based sensitivity derivates with those obtained directly from the field solver, derivatives have been extracted from the field software using a complex variable technique. The sensitivity derivatives from the reverse-mode time-accurate discrete adjoint method were then compared and demonstrated to agree to at least seven decimal places. As a demonstration of the assembled technologies, the optimization procedure successfully and efficiently modified the shape of two electromagnetic objects to reduce a specified cost function. A dielectric cube, under the influence of a propagating plane wave, was repositioned within a larger free space volume so that the field variables on the surface of the cube match desired values at a specified time. A similar demonstration case has also been conducted to modify the shape of a dielectric ellipsoid, under the same conditions as the cube.

Glasby, Ryan Steven

453

Study of plasma environments for the integrated Space Station electromagnetic analysis system  

NASA Technical Reports Server (NTRS)

The final report includes an analysis of various plasma effects on the electromagnetic environment of the Space Station Freedom. Effects of arcing are presented. Concerns of control of arcing by a plasma contactor are highlighted. Generation of waves by contaminant ions are studied and amplitude levels of the waves are estimated. Generation of electromagnetic waves by currents in the structure of the space station, driven by motional EMF, is analyzed and the radiation level is estimated.

Singh, Nagendra

1992-01-01

454

Characteristics of electromagnetic interference generated during discharge of Mylar samples. [spacecraft-environment interaction simulation  

NASA Technical Reports Server (NTRS)

This paper discusses the measurements of the electromagnetic interference (EMI) generated during discharges of Mylar samples. The two components of EMI, the conducted emission and the radiated emission, are characterized by the replacement current and the radiated RF spectrum respectively. The measured radiated RF spectra reveal important information on the source of the electromagnetic radiation. The possible sources are the replacement current pulse and the discharged generated plasma. The scaling of the amplitudes of the EMI, as a function of the area of the test sample, is also discussed.

Leung, P. L.

1984-01-01

455

Action Spectra for Human Skin Cells: Estimates of the Relative Cytotoxicity of the Middle Ultraviolet, Near Ultraviolet, and Violet Regions of Sunlight on Epidermal Keratinocytes1  

Microsoft Academic Search

Action spectra for the cytotoxic action of electromagnetic radiation in the solar range 280-434 nm have been determined for human fibroblasts and epidermal keratinocytes derived from the same foreskin biopsy. The spectra for the two cell types are close to identical and coincide with our previously published data for a human lymphoblastoid line indicating that the mechanism of inactivation of

Rex M. Tyrrell; Mireille Pidoux

456

Electromagnetic interference assessment of an ion drive electric propulsion system  

NASA Technical Reports Server (NTRS)

The electromagnetic interference (EMI) form elements of an ion drive electric propulsion system was analyzed, and the effects of EMI interaction with a typical interplanetary spacecraft engineering and scientific subsystems were predicted. SEMCAP, a computerized electromagnetic compatibility assessment code, was used to analyze the impact of EMI noise sources on 65 engineering/telemetry circuits and 48 plasma wave and planetary radio astronomy channels measuring over the range of 100 Hz to 40 MHz in a spacecraft of the Voyager type; manual methods were used to evaluate electrostatics, magnetics, and communications effects. Results indicate that some conducted and radiated spectra are in excess of electromagnetic compatibility specification limits; direct design changes may be required for filtering and shielding of thrust system elements. The worst source of broadband radiated noise appears to be the power processor. The magnetic field necessary to thruster operation is equivalent to about 18 amp-sq m per amp of beam current at right angles to the axis caused by the neutralizer/plume loop.

Whittlesey, A. C.

1979-01-01

457

Beta decay and other processes in strong electromagnetic fields  

NASA Astrophysics Data System (ADS)

We consider effects of the fields of strong electromagnetic waves on various characteristics of quantum processes. After a qualitative discussion of the effects of external fields on the energy spectra and angular distributions of the final-state particles as well as on the total probabilities of the processes (such as decay rates and total cross sections), we present a simple method of calculating the total probabilities of processes with production of nonrelativistic charged particles. Using nuclear ? decay as an example, we study the weak- and strong-field limits, as well as the field-induced ? decay of nuclei stable in the absence of the external fields, both in the tunneling and multiphoton regimes. We also consider the possibility of accelerating forbidden nuclear ? decays by lifting the forbiddeness due to the interaction of the parent or daughter nuclei with the field of a strong electromagnetic wave. It is shown that for currently attainable electromagnetic fields all effects on total ?-decay rates are unobservably small.

Akhmedov, E. Kh.

2011-09-01

458

INNOVATIVE ELECTROMAGNETIC SENSORS FOR PIPELINE CRAWLERS  

SciTech Connect

Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. However, not all pipelines can be inspected with current systems that move inside the pipeline propelled by the product flow. Inspection platforms that crawl slowly inside a pipeline are being developed to maneuver past the physical barriers that limit inspection. Battelle is building innovative electromagnetic sensors for pipeline crawlers. The various sensor types will assess a wide range of pipeline anomalies including corrosion, mechanical damage, cracking and seam weld defects. An implementation of two electromagnetic sensors were designed and tested. A pulsed eddy current system that uses sensors to measure the decay of induced eddy currents to establish the wall thickness has excellent potential. The results of experiments are comparable with magnetic flux leakage detecting 10% metal loss steps following a monotonic increase in signal strength. A rotating permanent remote field eddy current exciter was designed and built to produce strong signal levels at the receiver and reduce power consumption. Midway through the development of each technology, both sensor systems have produced results that warrant further development.

J. Bruce Nestleroth

2004-05-01

459

Amplification of electromagnetic signals by ion channels.  

PubMed Central

Cells may respond to the exposure of low-frequency electromagnetic fields with changes in cell division, ion influx, chemical reaction rates, etc. The chain of events leading to such responses is difficult to study, mainly because of extremely small energies associated with low-frequency fields, usually much smaller than the thermal noise level. However, the presence of stochastic systems (for instance, ion channels) provides a basis for signal amplification, and could therefore, despite the low signal-to-noise ratio of the primary response, lead to the transmission of weak signals along the signaling pathways of cells. We have explored this possibility for an ion channel model, and we present a theory, based on the formalism of stochastically driven processes, that relates the time averages of the ion channel currents to the amplitude and frequency of the applied signal. It is concluded from this theory that the signal-to-noise ratio increases with the number of channels, the magnitude of the rate constants, and the frequency response of the intracellular sensing system (for instance, a calcium oscillator). The amplification properties of the stochastic system are further deduced from numerical simulations carried out on the model, which consists of multiple identical two-state channels, and the behavior for different parameters is examined. Numerical estimates of the parameters show that under optimum conditions, even very weak low-frequency electromagnetic signals (<100 Hz and down to 100 microT) may be detected in a cellular system with a large number of ion channels.

Galvanovskis, J; Sandblom, J

1997-01-01

460

Electromagnetics for Detecting Shallow Tunnels  

NASA Astrophysics Data System (ADS)

Detecting tunnels by geophysical means, even very shallow ones, has been difficult, to say the least. Despite heavy R&D funding from the military since the early 70s, geophysicists have not produced tools that are simple and practical enough to meet the military needs. The initial interest and R&D funding on the subject perhaps started with the Vietcong tunnels in the 60s. Tunnels in the Korean DMZ, first found in the mid 70s, sharply escalated the R&D spending. During the 90s, covert tunnels along the US-Mexico border have kept the topic alive but at a minimal funding level. Most recent interest appears to be in the terrorism-related shallow tunnels, more or less anywhere in the regions of conflict. Despite the longstanding effort in the geophysical community under heavy public funding, there is a dearth of success stories where geophysicists can actually claim to have found hitherto unknown tunnels. For instance, geophysics has not discovered a single tunnel in Vietnam or in Korea! All tunnels across the Korean DMZ were found from human intelligence. The same is true to all illicit tunnels found along the southwestern border. The tunnels under discussion are clandestine, which implies that the people who built them do not wish others to succeed in finding them. The place around the tunnel, therefore, may not be the friendliest venue for surveyors to linger around. The situation requires tools that are fast, little noticeable, and hardly intrusive. Many geophysical sensors that require ground contacts, such as geophones and electrodes that are connected by a myriad of cables, may not be ideal in this situation. On the other hand, a sensor that can be carried by vehicle without stopping, and is nothing obviously noticeable to bystanders, could be much more acceptable. Working at unfriendly environment also requires forgoing our usual practices where we collect data leisurely and make pretty maps later. To be useful, geophysical tools must be able to process observed data and translate them into actionable results. They may in forms of audio (similar to the beeper of a landmine detector), strip chart, or even a 2D graphic display on a computer screen. In short, the tool must be able to declare a contact, audibly or graphically, in real time or shortly thereafter. In summary, we have two questions here. The first one is if any of the available geophysical tools can detect tunnels. If the answer is yes, then the next question is if any of them are able to perform fast in an unfriendly environment. Electromagnetic sensors may be able to meet the operational requirements: under what circumstances it can find tunnels would be another outstanding question.

Won, I.

2006-05-01