Five-Year Wilkinson Microwave Anisotropy Probe Observations: Data Processing, Sky Maps, and Basic Results

NASA Technical Reports Server (NTRS)

Hinshaw, G.; Weiland, J. L.; Hill, R. S.; Odegard, N.; Larson, D.; Bennett, C. L.; Dunkley, J.; Gold, B.; Greason, M. R.; Jarosik, N.;

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results

NASA Technical Reports Server (NTRS)

Weiland, J.L.; Hill, R.S.; Odegard, 3.; Larson, D.; Bennett, C.L.; Dunkley, J.; Jarosik, N.; Page, L.; Spergel, D.N.; Halpern, M.;

DETECTION OF ANOMALOUS MICROWAVE EMISSION IN THE PLEIADES REFLECTION NEBULA WITH WILKINSON MICROWAVE ANISOTROPY PROBE AND THE COSMOSOMAS EXPERIMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genova-Santos, R.; Rebolo, R.; Rubino-Martin, J. A.

2011-12-10

We present evidence for anomalous microwave emission (AME) in the Pleiades reflection nebula, using data from the seven-year release of the Wilkinson Microwave Anisotropy Probe and from the COSMOSOMAS (Cosmological Structures on Medium Angular Scales) experiment. The flux integrated in a 1 Degree-Sign radius around R.A. = 56.{sup 0}24, decl. = 23.{sup 0}78 (J2000) is 2.15 {+-} 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data show no significant emission, but allow one to set upper limits of 0.94 and 1.58 Jy (99.7% confidence level), respectively, at 10.9 and 14.7 GHz, which are crucial to pin down themore » AME spectrum at these frequencies, and to discard any other emission mechanisms which could have an important contribution to the signal detected at 22.8 GHz. We estimate the expected level of free-free emission from an extinction-corrected H{alpha} template, while the thermal dust emission is characterized from infrared DIRBE data and extrapolated to microwave frequencies. When we deduct the contribution from these two components at 22.8 GHz, the residual flux, associated with AME, is 2.12 {+-} 0.12 Jy (17.7{sigma}). The spectral energy distribution from 10 to 60 GHz can be accurately fitted with a model of electric dipole emission from small spinning dust grains distributed in two separated phases of molecular and atomic gas, respectively. The dust emissivity, calculated by correlating the 22.8 GHz data with 100 {mu}m data, is found to be 4.36 {+-} 0.17 {mu}K (MJy sr{sup -1}){sup -1}, a value considerably lower than in typical AME clouds, which present emissivities of {approx}20 {mu}K (MJy sr{sup -1}){sup -1}, although higher than the 0.2 {mu}K (MJy sr{sup -1}){sup -1} of the translucent cloud LDN 1780, where AME has recently been claimed. The physical properties of the Pleiades nebula, in particular its low extinction A{sub V} {approx} 0.4, indicate that this is indeed a much less opaque object than those where AME has usually been studied. This

First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission

NASA Technical Reports Server (NTRS)

Bennett, C. L.; Hill, R. S.; Hinshaw, G.; Nolta, M. R.; Odegard, N.; Page, L.; Spergel, D. N.; Weiland, J. L.; Wright, E. L.; Halpern, M.

2003-01-01

The WMAP mission has mapped the full sky to determine the geometry, content, and evolution of the universe. Full sky maps are made in five microwave frequency bands to separate the temperature anisotropy of the cosmic microwave background (CMB) from foreground emission, including diffuse Galactic emission and Galactic and extragalactic point sources. We define masks that excise regions of high foreground emission, so CMB analyses can became out with minimal foreground contamination. We also present maps and spectra of the individual emission components, leading to an improved understanding of Galactic astrophysical processes. The effectiveness of template fits to remove foreground emission from the WMAP data is also examined. These efforts result in a CMB map with minimal contamination and a demonstration that the WMAP CMB power spectrum is insensitive to residual foreground emission. We use a Maximum Entropy Method to construct a model of the Galactic emission components. The observed total Galactic emission matches the model to less than 1% and the individual model components are accurate to a few percent. We find that the Milky Way resembles other normal spiral galaxies between 408 MHz and 23 GHz, with a synchrotron spectral index that is flattest (beta(sub s) approx. -2.5) near star-forming regions, especially in the plane, and steepest (beta(sub s) approx. -3) in the halo. This is consistent with a picture of relativistic cosmic ray electron generation in star-forming regions and diffusion and convection within the plane. The significant synchrotron index steepening out of the plane suggests a diffusion process in which the halo electrons are trapped in the Galactic potential long enough to suffer synchrotron and inverse Compton energy losses and hence a spectral steepening. The synchrotron index is steeper in the WMAP bands than in lower frequency radio surveys, with a spectral break near 20 GHz to beta(sub s) less than -3. The modeled thermal dust spectral

First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission

NASA Astrophysics Data System (ADS)

Bennett, C. L.; Hill, R. S.; Hinshaw, G.; Nolta, M. R.; Odegard, N.; Page, L.; Spergel, D. N.; Weiland, J. L.; Wright, E. L.; Halpern, M.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wollack, E.

2003-09-01

The WMAP mission has mapped the full sky to determine the geometry, content, and evolution of the universe. Full-sky maps are made in five microwave frequency bands to separate the temperature anisotropy of the cosmic microwave background (CMB) from foreground emission, including diffuse Galactic emission and Galactic and extragalactic point sources. We define masks that excise regions of high foreground emission, so CMB analyses can be carried out with minimal foreground contamination. We also present maps and spectra of the individual emission components, leading to an improved understanding of Galactic astrophysical processes. The effectiveness of template fits to remove foreground emission from the WMAP data is also examined. These efforts result in a CMB map with minimal contamination and a demonstration that the WMAP CMB power spectrum is insensitive to residual foreground emission. We use a maximum entropy method to construct a model of the Galactic emission components. The observed total Galactic emission matches the model to less than 1%, and the individual model components are accurate to a few percent. We find that the Milky Way resembles other normal spiral galaxies between 408 MHz and 23 GHz, with a synchrotron spectral index that is flattest (βs~-2.5) near star-forming regions, especially in the plane, and steepest (βs~-3) in the halo. This is consistent with a picture of relativistic cosmic-ray electron generation in star-forming regions and diffusion and convection within the plane. The significant synchrotron index steepening out of the plane suggests a diffusion process in which the halo electrons are trapped in the Galactic potential long enough to suffer synchrotron and inverse Compton energy losses and hence a spectral steepening. The synchrotron index is steeper in the WMAP bands than in lower frequency radio surveys, with a spectral break near 20 GHz to βs<-3. The modeled thermal dust spectral index is also steep in the WMAP bands, with �

SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: PLANETS AND CELESTIAL CALIBRATION SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiland, J. L.; Odegard, N.; Hill, R. S.

2011-02-01

We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1{sigma} of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% {+-} 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry.more » Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 {mu}m, reproduce WMAP seasonally averaged observations of Mars within {approx}2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at {approx}30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with

Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Planets and Celestial Calibration Sources

NASA Astrophysics Data System (ADS)

Weiland, J. L.; Odegard, N.; Hill, R. S.; Wollack, E.; Hinshaw, G.; Greason, M. R.; Jarosik, N.; Page, L.; Bennett, C. L.; Dunkley, J.; Gold, B.; Halpern, M.; Kogut, A.; Komatsu, E.; Larson, D.; Limon, M.; Meyer, S. S.; Nolta, M. R.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.; Wright, E. L.

2011-02-01

We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1σ of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% ± 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 μm, reproduce WMAP seasonally averaged observations of Mars within ~2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at ~30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with uncertainties of a few percent for Tau A

A determination of the spectra of Galactic components observed by the Wilkinson Microwave Anisotropy Probe

NASA Astrophysics Data System (ADS)

Davies, R. D.; Dickinson, C.; Banday, A. J.; Jaffe, T. R.; Górski, K. M.; Davis, R. J.

2006-08-01

Wilkinson Microwave Anisotropy Probe (WMAP) data when combined with ancillary data on free-free, synchrotron and dust allow an improved understanding of the spectrum of emission from each of these components. Here, we examine the sky variation at intermediate latitudes using a cross-correlation technique. In particular, we compare the observed emission in 15 selected sky regions to three `standard' templates. The free-free emission of the diffuse ionized gas is fitted by a well-known spectrum at K and Ka band, but the derived emissivity corresponds to a mean electron temperature of ~4000-5000 K. This is inconsistent with estimates from Galactic HII regions although a variation in the derived ratio of Hα to free-free intensity by a factor of ~2 is also found from region to region. The origin of the discrepancy is unclear. The anomalous emission associated with dust is clearly detected in most of the 15 fields studied. The anomalous emission correlates well with the Finkbeiner, Davis & Schlegel model 8 predictions (FDS8) at 94 GHz, with an effective spectral index between 20 and 60 GHz, of β ~ -2.85. Furthermore, the emissivity varies by a factor of ~2 from cloud to cloud. A modestly improved fit to the anomalous dust at K band is provided by modulating the template by an estimate of the dust colour temperature, specifically FDS8 × Tn. We find a preferred value n ~ 1.6, although there is a scatter from region to region. Nevertheless, the preferred index drops to zero at higher frequencies where the thermal dust emission dominates. The synchrotron emission steepens between GHz frequencies and the WMAP bands. There are indications of spectral index variations across the sky but the current data are not precise enough to accurately quantify this from region to region. Our analysis of the WMAP data indicates strongly that the dust-correlated emission at the low WMAP frequencies has a spectrum which is compatible with spinning dust; we find no evidence for a

First Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Preliminary Maps and Basic Results

NASA Technical Reports Server (NTRS)

Bennett, C. L.; Halpern, M.; Hinshaw, G.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Page, L.; Spergel, D. N.; Tucker, G. S.

2003-01-01

We present full sky microwave maps in five frequency bands (23 to 94 GHz) from the WMAP first year sky survey. Calibration errors are less than 0.5% and the low systematic error level is well specified. The cosmic microwave background (CMB) is separated from the foregrounds using multifrequency data. The sky maps are consistent with the 7 in. full-width at half-maximum (FWHM) Cosmic Background Explorer (COBE) maps. We report more precise, but consistent, dipole and quadrupole values. The CMB anisotropy obeys Gaussian statistics with -58 less than f(sub NL) less than 134 (95% CL). The 2 less than or = l less than or = 900 anisotropy power spectrum is cosmic variance limited for l less than 354 with a signal-to-noise ratio greater than 1 per mode to l = 658. The temperature-polarization cross-power spectrum reveals both acoustic features and a large angle correlation from reionization. The optical depth of reionization is tau = 0.17 +/- 0.04, which implies a reionization epoch of t(sub r) = 180(sup +220, sub -80) Myr (95% CL) after the Big Bang at a redshift of z(sub r) = 20(sup +10, sub -9) (95% CL) for a range of ionization scenarios. This early reionization is incompatible with the presence of a significant warm dark matter density. A best-fit cosmological model to the CMB and other measures of large scale structure works remarkably well with only a few parameters. The age of the best-fit universe is t(sub 0) = 13.7 +/- 0.2 Gyr old. Decoupling was t(sub dec) = 379(sup +8, sub -7)kyr after the Big Bang at a redshift of z(sub dec) = 1089 +/- 1. The thickness of the decoupling surface was Delta(sub z(sub dec)) = 195 +/- 2. The matter density of the universe is Omega(sub m)h(sup 2) = 0.135(sup +0.008, sub -0.009) the baryon density is Omega(sub b)h(sup 2) = 0.0224 +/- 0.0009, and the total mass-energy of the universe is Omega(sub tot) = 1.02 +/- 0.02. There is progressively less fluctuation power on smaller scales, from WMAP to fine scale CMB measurements to galaxies

Miniaturized Wilkinson Power Dividers Utilizing Capacitive Loading

NASA Technical Reports Server (NTRS)

Scardelletti, Maximilian C.; Ponchak, George E.; Weller, Thomas M.

2001-01-01

This letter reports the miniaturization of a planar Wilkinson power divider by capacitive loading of the quarter wave transmission lines employed in conventional Wilkinson power dividers. Reduction of the transmission line segments from lambda/4 to between lambda/5 and lambda/12 are reported here. The input and output lines at the three ports and the lines comprising the divider itself are coplanar waveguide (CPW) and asymmetric coplanar stripline (ACPS), respectively. The 10 GHZ power dividers are fabricated on high resistivity silicon (HRS) and alumina wafers. These miniaturized dividers are 74% smaller than conventional Wilkinson power dividers, and have a return loss better than +30 dB and an insertion loss less than 0.55 dB. Design equations and a discussion about the effect of parasitic reactance on the isolation are presented for the first time.

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Bayesian Estimation of Cosmic Microwave Background Polarization Maps

NASA Astrophysics Data System (ADS)

Dunkley, J.; Spergel, D. N.; Komatsu, E.; Hinshaw, G.; Larson, D.; Nolta, M. R.; Odegard, N.; Page, L.; Bennett, C. L.; Gold, B.; Hill, R. S.; Jarosik, N.; Weiland, J. L.; Halpern, M.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wollack, E.; Wright, E. L.

2009-08-01

We describe a sampling method to estimate the polarized cosmic microwave background (CMB) signal from observed maps of the sky. We use a Metropolis-within-Gibbs algorithm to estimate the polarized CMB map, containing Q and U Stokes parameters at each pixel, and its covariance matrix. These can be used as inputs for cosmological analyses. The polarized sky signal is parameterized as the sum of three components: CMB, synchrotron emission, and thermal dust emission. The polarized Galactic components are modeled with spatially varying power-law spectral indices for the synchrotron, and a fixed power law for the dust, and their component maps are estimated as by-products. We apply the method to simulated low-resolution maps with pixels of side 7.2 deg, using diagonal and full noise realizations drawn from the WMAP noise matrices. The CMB maps are recovered with goodness of fit consistent with errors. Computing the likelihood of the E-mode power in the maps as a function of optical depth to reionization, τ, for fixed temperature anisotropy power, we recover τ = 0.091 ± 0.019 for a simulation with input τ = 0.1, and mean τ = 0.098 averaged over 10 simulations. A "null" simulation with no polarized CMB signal has maximum likelihood consistent with τ = 0. The method is applied to the five-year WMAP data, using the K, Ka, Q, and V channels. We find τ = 0.090 ± 0.019, compared to τ = 0.086 ± 0.016 from the template-cleaned maps used in the primary WMAP analysis. The synchrotron spectral index, β, averaged over high signal-to-noise pixels with standard deviation σ(β) < 0.25, but excluding ~6% of the sky masked in the Galactic plane, is -3.03 ± 0.04. This estimate does not vary significantly with Galactic latitude, although includes an informative prior. WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

Global universe anisotropy probed by the alignment of structures in the cosmic microwave background.

PubMed

Wiaux, Y; Vielva, P; Martínez-González, E; Vandergheynst, P

2006-04-21

We question the global universe isotropy by probing the alignment of local structures in the cosmic microwave background (CMB) radiation. The original method proposed relies on a steerable wavelet decomposition of the CMB signal on the sphere. The analysis of the first-year Wilkinson Microwave Anisotropy Probe data identifies a mean preferred plane with a normal direction close to the CMB dipole axis, and a mean preferred direction in this plane, very close to the ecliptic poles axis. Previous statistical anisotropy results are thereby synthesized, but further analyses are still required to establish their origin.

Imprints of spherical nontrivial topologies on the cosmic microwave background.

PubMed

Niarchou, Anastasia; Jaffe, Andrew

2007-08-24

The apparent low power in the cosmic microwave background (CMB) temperature anisotropy power spectrum derived from the Wilkinson Microwave Anisotropy Probe motivated us to consider the possibility of a nontrivial topology. We focus on simple spherical multiconnected manifolds and discuss their implications for the CMB in terms of the power spectrum, maps, and the correlation matrix. We perform a Bayesian model comparison against the fiducial best-fit cold dark matter model with a cosmological constant based both on the power spectrum and the correlation matrix to assess their statistical significance. We find that the first-year power spectrum shows a slight preference for the truncated cube space, but the three-year data show no evidence for any of these spaces.

SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larson, D.; Bennett, C. L.; Gold, B.

2011-02-01

1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of {Lambda}CDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the {Lambda}CDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n{sub s} , is biased high, but only by 0.09{sigma}, while the remaining parameters are biased by <0.15{sigma}. The improvement in the third peak measurement leads to tighter lower limits from WMAP on the number of relativistic degrees of freedom (e.g., neutrinos) in the early universe: N{sub eff}>2.7(95%CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be Y{sub He} = 0.28{sup +0.14}{sub -0.15}, and with data from higher-resolution cosmic microwave background experiments included, we now establish the existence of pre-stellar helium at >3{sigma}. These new WMAP measurements provide important tests of big bang cosmology.« less

Bayesian Analysis of the Power Spectrum of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, Jeffrey B.; Eriksen, H. K.; O'Dwyer, I. J.; Wandelt, B. D.

2005-01-01

There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background. The sky, when viewed in the microwave, is very uniform, with a nearly perfect blackbody spectrum at 2.7 degrees. Very small amplitude brightness fluctuations (to one part in a million!!) trace small density perturbations in the early universe (roughly 300,000 years after the Big Bang), which later grow through gravitational instability to the large-scale structure seen in redshift surveys... In this talk, I will discuss a Bayesian formulation of this problem; discuss a Gibbs sampling approach to numerically sampling from the Bayesian posterior, and the application of this approach to the first-year data from the Wilkinson Microwave Anisotropy Probe. I will also comment on recent algorithmic developments for this approach to be tractable for the even more massive data set to be returned from the Planck satellite.

SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komatsu, E.; Smith, K. M.; Spergel, D. N.

2011-02-01

The combination of seven-year data from WMAP and improved astrophysical data rigorously tests the standard cosmological model and places new constraints on its basic parameters and extensions. By combining the WMAP data with the latest distance measurements from the baryon acoustic oscillations (BAO) in the distribution of galaxies and the Hubble constant (H{sub 0}) measurement, we determine the parameters of the simplest six-parameter {Lambda}CDM model. The power-law index of the primordial power spectrum is n{sub s} = 0.968 {+-} 0.012 (68% CL) for this data combination, a measurement that excludes the Harrison-Zel'dovich-Peebles spectrum by 99.5% CL. The other parameters, includingmore » those beyond the minimal set, are also consistent with, and improved from, the five-year results. We find no convincing deviations from the minimal model. The seven-year temperature power spectrum gives a better determination of the third acoustic peak, which results in a better determination of the redshift of the matter-radiation equality epoch. Notable examples of improved parameters are the total mass of neutrinos, {Sigma}M{sub {nu}} < 0.58 eV(95%CL), and the effective number of neutrino species, N{sub eff} = 4.34{sup +0.86}{sub -0.88} (68% CL), which benefit from better determinations of the third peak and H{sub 0}. The limit on a constant dark energy equation of state parameter from WMAP+BAO+H{sub 0}, without high-redshift Type Ia supernovae, is w = -1.10 {+-} 0.14 (68% CL). We detect the effect of primordial helium on the temperature power spectrum and provide a new test of big bang nucleosynthesis by measuring Y{sub p} = 0.326 {+-} 0.075 (68% CL). We detect, and show on the map for the first time, the tangential and radial polarization patterns around hot and cold spots of temperature fluctuations, an important test of physical processes at z = 1090 and the dominance of adiabatic scalar fluctuations. The seven-year polarization data have significantly improved: we now

Long-range correlation in cosmic microwave background radiation.

PubMed

Movahed, M Sadegh; Ghasemi, F; Rahvar, Sohrab; Tabar, M Reza Rahimi

2011-08-01

We investigate the statistical anisotropy and gaussianity of temperature fluctuations of Cosmic Microwave Background (CMB) radiation data from the Wilkinson Microwave Anisotropy Probe survey, using the Multifractal Detrended Fluctuation Analysis, Rescaled Range, and Scaled Windowed Variance methods. Multifractal Detrended Fluctuation Analysis shows that CMB fluctuations has a long-range correlation function with a multifractal behavior. By comparing the shuffled and surrogate series of CMB data, we conclude that the multifractality nature of the temperature fluctuation of CMB radiation is mainly due to the long-range correlations, and the map is consistent with a gaussian distribution.

First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles and Window Functions

NASA Astrophysics Data System (ADS)

Page, L.; Barnes, C.; Hinshaw, G.; Spergel, D. N.; Weiland, J. L.; Wollack, E.; Bennett, C. L.; Halpern, M.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Tucker, G. S.; Wright, E. L.

2003-09-01

Knowledge of the beam profiles is of critical importance for interpreting data from cosmic microwave background experiments. In this paper, we present the characterization of the in-flight optical response of the WMAP satellite. The main-beam intensities have been mapped to <=-30 dB of their peak values by observing Jupiter with the satellite in the same observing mode as for CMB observations. The beam patterns closely follow the prelaunch expectations. The full width at half-maximum is a function of frequency and ranges from 0.82d at 23 GHz to 0.21d at 94 GHz; however, the beams are not Gaussian. We present (a) the beam patterns for all 10 differential radiometers, showing that the patterns are substantially independent of polarization in all but the 23 GHz channel; (b) the effective symmetrized beam patterns that result from WMAP's compound spin observing pattern; (c) the effective window functions for all radiometers and the formalism for propagating the window function uncertainty; and (d) the conversion factor from point-source flux to antenna temperature. A summary of the systematic uncertainties, which currently dominate our knowledge of the beams, is also presented. The constancy of Jupiter's temperature within a frequency band is an essential check of the optical system. The tests enable us to report a calibration of Jupiter to 1%-3% accuracy relative to the CMB dipole. WMAP is the result of a partnership between Princeton University and the NASA Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

COSMIC MICROWAVE BACKGROUND POLARIZATION AND TEMPERATURE POWER SPECTRA ESTIMATION USING LINEAR COMBINATION OF WMAP 5 YEAR MAPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samal, Pramoda Kumar; Jain, Pankaj; Saha, Rajib

We estimate cosmic microwave background (CMB) polarization and temperature power spectra using Wilkinson Microwave Anisotropy Probe (WMAP) 5 year foreground contaminated maps. The power spectrum is estimated by using a model-independent method, which does not utilize directly the diffuse foreground templates nor the detector noise model. The method essentially consists of two steps: (1) removal of diffuse foregrounds contamination by making linear combination of individual maps in harmonic space and (2) cross-correlation of foreground cleaned maps to minimize detector noise bias. For the temperature power spectrum we also estimate and subtract residual unresolved point source contamination in the cross-power spectrummore » using the point source model provided by the WMAP science team. Our TT, TE, and EE power spectra are in good agreement with the published results of the WMAP science team. We perform detailed numerical simulations to test for bias in our procedure. We find that the bias is small in almost all cases. A negative bias at low l in TT power spectrum has been pointed out in an earlier publication. We find that the bias-corrected quadrupole power (l(l + 1)C{sub l} /2{pi}) is 532 {mu}K{sup 2}, approximately 2.5 times the estimate (213.4 {mu}K{sup 2}) made by the WMAP team.« less

Design of Compact Wilkinson Power Divider with Harmonic Suppression using T-Shaped Resonators

NASA Astrophysics Data System (ADS)

Siahkamari, Hesam; Yasoubi, Zahra; Jahanbakhshi, Maryam; Mousavi, Seyed Mohammad Hadi; Siahkamari, Payam; Nouri, Mohammad Ehsan; Azami, Sajad; Azadi, Rasoul

2018-04-01

A novel scheme of a shrunken Wilkinson power divider with harmonic suppression, using two identical resonators in the conventional Wilkinson power divider is designed. Moreover, the LC equivalent circuit and its relevant formulas are provided. To substantiate the functionality and soundness of design, a microstrip implementation of this design operating at 1 GHz with the second to eighth harmonic suppression, is developed. The proposed circuit is relatively smaller than the conventional circuit, (roughly 55% of the conventional circuit). Simulation and measurement results for the proposed scheme, which are highly consistent with one another, indicate a good insertion loss about 3.1 dB, input return loss of 20 dB and isolation of 20 dB, while sustaining high-power handling capability over the Wilkinson power divider.

The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2009-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approx. 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time.

Model-independent test for scale-dependent non-Gaussianities in the cosmic microwave background.

PubMed

Räth, C; Morfill, G E; Rossmanith, G; Banday, A J; Górski, K M

2009-04-03

We present a model-independent method to test for scale-dependent non-Gaussianities in combination with scaling indices as test statistics. Therefore, surrogate data sets are generated, in which the power spectrum of the original data is preserved, while the higher order correlations are partly randomized by applying a scale-dependent shuffling procedure to the Fourier phases. We apply this method to the Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background and find signatures for non-Gaussianities on large scales. Further tests are required to elucidate the origin of the detected anomalies.

Enhanced polarization of the cosmic microwave background radiation from thermal gravitational waves.

PubMed

Bhattacharya, Kaushik; Mohanty, Subhendra; Nautiyal, Akhilesh

2006-12-22

If inflation was preceded by a radiation era, then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently, the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplifies the B-mode polarization of the cosmic microwave background radiation by an order of magnitude at large angles, which may now be in the range of observability of the Wilkinson Microwave Anisotropy Probe.

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Beam Maps and Window Functions

NASA Technical Reports Server (NTRS)

Hill, R.S.; Weiland, J.L.; Odegard, N.; Wollack, E.; Hinshaw, G.; Larson, D.; Bennett, C.L.; Halpern, M.; Kogut, A.; Page, L.;

Ellipsoidal universe can solve the cosmic microwave background quadrupole problem.

PubMed

Campanelli, L; Cea, P; Tedesco, L

2006-09-29

The recent 3 yr Wilkinson Microwave Anisotropy Probe data have confirmed the anomaly concerning the low quadrupole amplitude compared to the best-fit Lambda-cold dark matter prediction. We show that by allowing the large-scale spatial geometry of our universe to be plane symmetric with eccentricity at decoupling or order 10(-2), the quadrupole amplitude can be drastically reduced without affecting higher multipoles of the angular power spectrum of the temperature anisotropy.

Smoot Cosmology Group

Science.gov Websites

History of COBE project Structure in the COBE differential microwave radiometer first-year maps. Smoot, et (Wilkinson Microwave Anisotropy Probe) CMB satellite 5 year data papers Introduction NASA's COBE (Cosmic compare the spectrum of the cosmic microwave background radiation with that from a precise blackbody. Data

Robust constraint on cosmic textures from the cosmic microwave background.

PubMed

Feeney, Stephen M; Johnson, Matthew C; Mortlock, Daniel J; Peiris, Hiranya V

2012-06-15

Fluctuations in the cosmic microwave background (CMB) contain information which has been pivotal in establishing the current cosmological model. These data can also be used to test well-motivated additions to this model, such as cosmic textures. Textures are a type of topological defect that can be produced during a cosmological phase transition in the early Universe, and which leave characteristic hot and cold spots in the CMB. We apply bayesian methods to carry out a rigorous test of the texture hypothesis, using full-sky data from the Wilkinson Microwave Anisotropy Probe. We conclude that current data do not warrant augmenting the standard cosmological model with textures. We rule out at 95% confidence models that predict more than 6 detectable cosmic textures on the full sky.

Applications of the Wilkinson Model of Writing Maturity to College Writing.

ERIC Educational Resources Information Center

Sternglass, Marilyn

1982-01-01

Examines the four-category model developed by Andrew Wilkinson at the University of Essex (England) to assess growth in writing maturity. The four measures of development are stylistic, affective, cognitive, and moral. Each has several subcategories. Includes college student essays to illustrate the model. (HTH)

Searching for CPT violation with cosmic microwave background data from WMAP and BOOMERANG.

PubMed

Feng, Bo; Li, Mingzhe; Xia, Jun-Qing; Chen, Xuelei; Zhang, Xinmin

2006-06-09

We search for signatures of Lorentz and violations in the cosmic microwave background (CMB) temperature and polarization anisotropies by using the Wilkinson Microwave Anisotropy Probe (WMAP) and the 2003 flight of BOOMERANG (B03) data. We note that if the Lorentz and symmetries are broken by a Chern-Simons term in the effective Lagrangian, which couples the dual electromagnetic field strength tensor to an external four-vector, the polarization vectors of propagating CMB photons will get rotated. Using the WMAP data alone, one could put an interesting constraint on the size of such a term. Combined with the B03 data, we found that a nonzero rotation angle of the photons is mildly favored: [Formula: See Text].

The Python Sky Model: software for simulating the Galactic microwave sky

NASA Astrophysics Data System (ADS)

Thorne, B.; Dunkley, J.; Alonso, D.; Næss, S.

2017-08-01

We present a numerical code to simulate maps of Galactic emission in intensity and polarization at microwave frequencies, aiding in the design of cosmic microwave background experiments. This python code builds on existing efforts to simulate the sky by providing an easy-to-use interface and is based on publicly available data from the WMAP (Wilkinson Microwave Anisotropy Probe) and Planck satellite missions. We simulate synchrotron, thermal dust, free-free and anomalous microwave emission over the whole sky, in addition to the cosmic microwave background, and include a set of alternative prescriptions for the frequency dependence of each component, for example, polarized dust with multiple temperatures and a decorrelation of the signals with frequency, which introduce complexity that is consistent with current data. We also present a new prescription for adding small-scale realizations of these components at resolutions greater than current all-sky measurements. The usefulness of the code is demonstrated by forecasting the impact of varying foreground complexity on the recovered tensor-to-scalar ratio for the LiteBIRD satellite. The code is available at: https://github.com/bthorne93/PySM_public.

The Complexities of Interstellar Dust and the Implications for the Small-scale Structure in the Cosmic Microwave Background

NASA Astrophysics Data System (ADS)

Verschuur, G. L.; Schmelz, J. T.

2018-02-01

A detailed comparison of the full range of PLANCK and Wilkinson Microwave Anisotropy Probe data for small (2° × 2°) areas of sky and the Cosmic Microwave Background Internal Linear Combination (ILC) maps reveals that the structure of foreground dust may be more complex than previously thought. If 857 and 353 GHz emission is dominated by galactic dust at a distance < few hundred light years, then it should not resemble the cosmological ILC structure originating at a distance ∼13 billion light years. In some areas of sky, however, we find strong morphological correlations, forcing us to consider the possibility that the foreground subtraction is not complete. Our data also show that there is no single answer for the question: “to what extent does dust contaminate the cosmologically important 143 GHz data?” In some directions, the contamination appears to be quite strong, but in others, it is less of an issue. This complexity needs to be taken in account in order to derive an accurate foreground mask in the quest to understand the Cosmic Microwave Background small-scale structure. We hope that a continued investigation of these data will lead to a definitive answer to the question above and, possibly, to new scientific insights on interstellar matter, the Cosmic Microwave Background, or both.

Evidence for dark energy from the cosmic microwave background alone using the Atacama Cosmology Telescope lensing measurements.

PubMed

Sherwin, Blake D; Dunkley, Joanna; Das, Sudeep; Appel, John W; Bond, J Richard; Carvalho, C Sofia; Devlin, Mark J; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Irwin, Kent D; Klein, Jeff; Kosowsky, Arthur; Marriage, Tobias A; Marsden, Danica; Moodley, Kavilan; Menanteau, Felipe; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; Wollack, Ed

2011-07-08

For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with w = -1 dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density Ω(Λ) confirms other measurements from supernovae, galaxy clusters, and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.

Evidence for Dark Energy from the Cosmic Microwave Background Alone Using the Atacama Cosmology Telescope Lensing Measurements

NASA Technical Reports Server (NTRS)

Sherwin, Blake D.; Dunkley, Joanna; Das, Sudeep; Appel, John W.; Bond, J. Richard; Carvalho, C. Sofia; Devlin, Mark J.; Duenner, Rolando; Essinger-Hileman, Thomas; Fowler, Joesph J.;

Radio Source Contributions to the Microwave Sky

NASA Astrophysics Data System (ADS)

Boughn, S. P.; Partridge, R. B.

2008-03-01

Cross-correlations of the Wilkinson Microwave Anisotropy Probe (WMAP) full sky K-, Ka-, Q-, V-, and W-band maps with the 1.4 GHz NVSS source count map and the HEAO I A2 2-10 keV full sky X-ray flux map are used to constrain rms fluctuations due to unresolved microwave sources in the WMAP frequency range. In the Q band (40.7 GHz), a lower limit, taking account of only those fluctuations correlated with the 1.4 GHz radio source counts and X-ray flux, corresponds to an rms Rayleigh-Jeans temperature of ˜2 μK for a solid angle of 1 deg2 assuming that the cross-correlations are dominated by clustering, and ˜1 μK if dominated by Poisson fluctuations. The correlated fluctuations at the other bands are consistent with a β = -2.1 ± 0.4 frequency spectrum. If microwave sources are distributed similarly in redshift to the radio and X-ray sources and are similarly clustered, then the implied total rms microwave fluctuations correspond to ˜5 μK. While this value should be considered no more than a plausible estimate, it is similar to that implied by the excess, small angular scale fluctuations observed in the Q band by WMAP and is consistent with estimates made by extrapolating low-frequency source counts.

The Wilkinson Microwave Anisotropy Probe (WMAP) Source Catalog

NASA Technical Reports Server (NTRS)

Wright, E.L.; Chen, X.; Odegard, N.; Bennett, C.L.; Hill, R.S.; Hinshaw, G.; Jarosik, N.; Komatsu, E.; Nolta, M.R.; Page, L.;

A new model of the microwave polarized sky for CMB experiments

NASA Astrophysics Data System (ADS)

Hervías-Caimapo, Carlos; Bonaldi, Anna; Brown, Michael L.

2016-10-01

We present a new model of the microwave sky in polarization that can be used to simulate data from cosmic microwave background polarization experiments. We exploit the most recent results from the Planck satellite to provide an accurate description of the diffuse polarized foreground synchrotron and thermal dust emission. Our model can include the two mentioned foregrounds, and also a constructed template of Anomalous Microwave Emission. Several options for the frequency dependence of the foregrounds can be easily selected, to reflect our uncertainties and to test the impact of different assumptions. Small angular scale features can be added to the foreground templates to simulate high-resolution observations. We present tests of the model outputs to show the excellent agreement with Planck and Wilkinson Microwave Anisotropy Probe (WMAP) data. We determine the range within which the foreground spectral indices can be varied to be consistent with the current data. We also show forecasts for a high-sensitivity, high-resolution full-sky experiment such as the Cosmic ORigin Explorer. Our model is released as a PYTHON script that is quick and easy to use, available at http://www.jb.man.ac.uk/chervias.

Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background.

PubMed

Luminet, Jean-Pierre; Weeks, Jeffrey R; Riazuelo, Alain; Lehoucq, Roland; Uzan, Jean-Philippe

2003-10-09

The current 'standard model' of cosmology posits an infinite flat universe forever expanding under the pressure of dark energy. First-year data from the Wilkinson Microwave Anisotropy Probe (WMAP) confirm this model to spectacular precision on all but the largest scales. Temperature correlations across the microwave sky match expectations on angular scales narrower than 60 degrees but, contrary to predictions, vanish on scales wider than 60 degrees. Several explanations have been proposed. One natural approach questions the underlying geometry of space--namely, its curvature and topology. In an infinite flat space, waves from the Big Bang would fill the universe on all length scales. The observed lack of temperature correlations on scales beyond 60 degrees means that the broadest waves are missing, perhaps because space itself is not big enough to support them. Here we present a simple geometrical model of a finite space--the Poincaré dodecahedral space--which accounts for WMAP's observations with no fine-tuning required. The predicted density is Omega(0) approximately 1.013 > 1, and the model also predicts temperature correlations in matching circles on the sky.

Cross-correlation of WISE galaxies with the cosmic microwave background

NASA Astrophysics Data System (ADS)

Goto, Tomotsugu; Szapudi, István.; Granett, Benjamin R.

2012-05-01

We estimated the cross-power spectra of a galaxy sample from the Wide-field Infrared Survey Explorer (WISE) survey with the 7-year Wilkinson Microwave Anisotropy Probe (WMAP) temperature anisotropy maps. A conservatively selected galaxy sample covers ˜13 000 deg2 with a median redshift of z= 0.15. Cross-power spectra show correlations between the two data sets with no discernible dependence on the WMAPQ, V and W frequency bands. We interpret these results in terms of the integrated Sachs-Wolfe (ISW) effect: for the |b| > 20° sample at l= 6-87, we measure the amplitude (normalized to be 1 for vanilla Λ cold dark matter expectation) of the signal to be 3.4 ± 1.1, i.e. 3.1σ detection. We discuss other possibilities, but at face value the detection of the linear ISW effect in a flat universe is caused by large-scale decaying potentials, a sign of accelerated expansion driven by dark energy.

SIGNIFICANT FOREGROUND UNRELATED NON-ACOUSTIC ANISOTROPY ON THE 1 DEGREE SCALE IN WILKINSON MICROWAVE ANISOTROPY PROBE 5-YEAR OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang Bizhu; Zhang Shuangnan; Lieu, Richard

2010-01-01

The spectral variation of the cosmic microwave background (CMB) as observed by WMAP was tested using foreground reduced WMAP5 data, by producing subtraction maps at the 1 deg. angular resolution between the two cosmological bands of V and W, for masked sky areas that avoid the Galactic disk. The resulting V - W map revealed a non-acoustic signal over and above the WMAP5 pixel noise, with two main properties. First, it possesses quadrupole power at the approx1 muK level which may be attributed to foreground residuals. Second, it fluctuates also at all values of l> 2, especially on the 1more » deg. scale (200 approx< l approx< 300). The behavior is random and symmetrical about zero temperature with an rms approx7 muK, or 10% of the maximum CMB anisotropy, which would require a 'cosmic conspiracy' among the foreground components if it is a consequence of their existence. Both anomalies must be properly diagnosed and corrected if 'precision' cosmology is the claim. The second anomaly is, however, more interesting because it opens the question on whether the CMB anisotropy genuinely represents primordial density seeds.« less

The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2009-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approximately 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2008-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approximately 1100. Data from the first five years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown university; University of British Columbia; and University of California, Los Angeles.

The Cosmic Microwave Background Radiation-A Unique Window on the Early Universe

NASA Technical Reports Server (NTRS)

Hinshaw, Gary

2010-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 11 00. Data from the first seven years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

The Advanced Technology Microwave Sounder (ATMS): First Year On-Orbit

NASA Technical Reports Server (NTRS)

Kim, Edward J.

2012-01-01

The Advanced Technology Microwave Sounder (ATMS) is a new satellite microwave sounding sensor designed to provide operational weather agencies with atmospheric temperature and moisture profile information for global weather forecasting and climate applications. A TMS will continue the microwave sounding capabilities first provided by its predecessors, the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU). The first flight unit was launched a year ago in October, 2011 aboard the Suomi-National Polar-Orbiting Partnership (S-NPP) satellite, part of the new Joint Polar-Orbiting Satellite System (JPSS). Microwave soundings by themselves are the highest-impact input data used by Numerical Weather Prediction models; and A TMS, when combined with the Cross-track Infrared Sounder (CrIS), forms the Cross-track Infrared and Microwave Sounding Suite (CrIMSS). The microwave soundings help meet sounding requirements under cloudy sky conditions and provide key profile information near the surface. ATMS was designed & built by Aerojet Corporation in Azusa, California, (now Northrop Grumman Electronic Systems). It has 22 channels spanning 23-183 GHz, closely following the channel set of the MSU, AMSU-AI/2, AMSU-B, Microwave Humidity Sounder (MHS), and Humidity Sounder for Brazil (HSB). It continues their cross-track scanning geometry, but for the first time, provides Nyquist sample spacing. All this is accomplished with approximately V. the volume, Y, the mass, and Y, the power of the three AMSUs. A description will be given of its performance from its first year of operation as determined by post-launch calibration activities. These activities include radiometric calibration using the on-board warm targets and cold space views, and geolocation determination. Example imagery and zooms of specific weather events will be shown. The second ATMS flight model is currently under construction and planned for launch on the "Jl" satellite of the JPSS program in

A Study of Direct Digital Manufactured RF/Microwave Packaging

NASA Astrophysics Data System (ADS)

Stratton, John W. I.

Various facets of direct digital manufactured (DDM) microwave packages are studied. The rippled surface inherent in fused deposition modeling (FDM) fabricated geometries is modeled in Ansoft HFSS, and its effect on the performance of microstrip transmission lines is assessed via simulation and measurement. The thermal response of DDM microstrip transmission lines is analyzed over a range of RF input powers, and linearity is confirmed over that range. Two IC packages are embedded into DDM printed circuit boards, and their performance is analyzed. The first is a low power RF switch, and the second is an RF front end device that includes a low noise amplifier (LNA) and a power amplifier (PA). The RF switch is shown to perform well, as compared to a layout designed for a Rogers 4003C microwave laminate substrate. The LNA performs within datasheet specifications. The power amplifier generates substantial heat, so a thermal management attempt is described. Finally, a capacitively loaded 6dB Wilkinson power divider is designed and fabricated using DDM techniques and materials. Its performance is analyzed and compared to simulation. The device is shown to compare favorably to a similar device fabricated on a Rogers 4003C microwave laminate using traditional printed circuit board techniques.

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Galactic Foreground Emission

NASA Technical Reports Server (NTRS)

Gold, B.; Bennett, C.L.; Larson, D.; Hill, R.S.; Odegard, N.; Weiland, J.L.; Hinshaw, G.; Kogut, A.; Wollack, E.; Page, L.;

Angular power spectrum of the FASTICA cosmic microwave background component from Background Emission Anisotropy Scanning Telescope data

NASA Astrophysics Data System (ADS)

Donzelli, S.; Maino, D.; Bersanelli, M.; Childers, J.; Figueiredo, N.; Lubin, P. M.; Meinhold, P. R.; O'Dwyer, I. J.; Seiffert, M. D.; Villela, T.; Wandelt, B. D.; Wuensche, C. A.

2006-06-01

We present the angular power spectrum of the cosmic microwave background (CMB) component extracted with FASTICA from the Background Emission Anisotropy Scanning Telescope (BEAST) data. BEAST is a 2.2-m off-axis telescope with a focal plane comprising eight elements at Q (38-45 GHz) and Ka (26-36 GHz) bands. It operates from the UC (University of California) White Mountain Research Station at an altitude of 3800 m. The BEAST CMB angular power spectrum has already been calculated by O'Dwyer et al. using only the Q-band data. With two input channels, FASTICA returns two possible independent components. We found that one of these two has an unphysical spectral behaviour, while the other is a reasonable CMB component. After a detailed calibration procedure based on Monte Carlo (MC) simulations, we extracted the angular power spectrum for the identified CMB component and found a very good agreement with the already published BEAST CMB angular power spectrum and with the Wilkinson Microwave Anisotropy Probe (WMAP) data.

First measurement of the bulk flow of nearby galaxies using the cosmic microwave background

NASA Astrophysics Data System (ADS)

Lavaux, Guilhem; Afshordi, Niayesh; Hudson, Michael J.

2013-04-01

Peculiar velocities in the nearby Universe can be measured via the kinetic Sunyaev-Zel'dovich (kSZ) effect. Using a statistical method based on an optimized cross-correlation with nearby galaxies, we extract the kSZ signal generated by plasma halo of galaxies from the cosmic microwave background (CMB) temperature anisotropies observed by the Wilkinson Microwave Anisotropy Probe (WMAP). Marginalizing over the thermal Sunyaev-Zel'dovich contribution from clusters of galaxies, possible unresolved point source contamination, and Galactic foregrounds, we find a kSZ bulk flow signal present at the ˜90 per cent confidence level in the seven-year WMAP data. When only galaxies within 50 h-1 Mpc are included in the kSZ template, we find a bulk flow in the CMB frame of |V| = 533 ± 263 km s-1, in the direction l = 324 ± 27, b = -7 ± 17, consistent with bulk flow measurements on a similar scale using classical distance indicators. We show how this comparison constrains, for the first time, the (ionized) baryonic budget in the local universe. On very large (˜500 h-1 Mpc) scales, we find a 95 per cent upper limit of 470 km s-1, inconsistent with some analyses of bulk flow of clusters from the kSZ. We estimate that the significance of the bulk flow signal may increase to 3σ-5σ using data from the Planck probe.

Global Snow-Cover Evolution from Twenty Years of Satellite Passive Microwave Data

USGS Publications Warehouse

Mognard, N.M.; Kouraev, A.V.; Josberger, E.G.

2003-01-01

Starting in 1979 with the SMMR (Scanning Multichannel Microwave Radiometer) instrument onboard the satellite NIMBUS-7 and continuing since 1987 with the SSMI (Special Sensor Microwave Imager) instrument on board the DMSP (Defence Meteorological Satellite Program) series, more then twenty years of satellite passive microwave data are now available. This dataset has been processed to analyse the evolution of the global snow cover. This work is part of the AICSEX project from the 5th Framework Programme of the European Community. The spatio-temporal evolution of the satellite-derived yearly snow maximum extent and the timing of the spring snow melt were estimated and analysed over the Northern Hemisphere. Significant differences between the evolution of the yearly maximum snow extent in Eurasia and in North America were found. A positive correlation between the maximum yearly snow cover extent and the ENSO index was obtained. High interannual spatio-temporal variability characterises the timing of snow melt in the spring. Twenty-year trends in the timing of spring snow melt have been computed and compared with spring air temperature trends for the same period and the same area. In most parts of Eurasia and in the central and western parts of North America the tendency has been for earlier snow melt. In northeastern Canada, a large area of positive trends, where snow melt timing starts later than in the early 1980s, corresponds to a region of positive trends of spring air temperature observed over the same period.

Two-Volt Josephson Arbitrary Waveform Synthesizer Using Wilkinson Dividers.

PubMed

Flowers-Jacobs, Nathan E; Fox, Anna E; Dresselhaus, Paul D; Schwall, Robert E; Benz, Samuel P

2016-09-01

The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal voltage converters and precision voltage measurements that require state-of-the-art quantum accuracy, stability, and signal-to-noise ratio. We achieved this increase in output voltage by using four on-chip Wilkinson dividers and eight inner-outer dc blocks, which enable biasing of eight Josephson junction (JJ) arrays with high-speed inputs from only four high-speed pulse generator channels. This approach halves the number of pulse generator channels required in future JAWS systems. We also implemented on-chip superconducting interconnects between JJ arrays, which reduces systematic errors and enables a new modular chip package. Finally, we demonstrate a new technique for measuring and visualizing the operating current range that reduces the measurement time by almost two orders of magnitude and reveals the relationship between distortion in the output spectrum and output pulse sequence errors.

COSMIC MICROWAVE BACKGROUND LIKELIHOOD APPROXIMATION FOR BANDED PROBABILITY DISTRIBUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gjerløw, E.; Mikkelsen, K.; Eriksen, H. K.

We investigate sets of random variables that can be arranged sequentially such that a given variable only depends conditionally on its immediate predecessor. For such sets, we show that the full joint probability distribution may be expressed exclusively in terms of uni- and bivariate marginals. Under the assumption that the cosmic microwave background (CMB) power spectrum likelihood only exhibits correlations within a banded multipole range, Δl{sub C}, we apply this expression to two outstanding problems in CMB likelihood analysis. First, we derive a statistically well-defined hybrid likelihood estimator, merging two independent (e.g., low- and high-l) likelihoods into a single expressionmore » that properly accounts for correlations between the two. Applying this expression to the Wilkinson Microwave Anisotropy Probe (WMAP) likelihood, we verify that the effect of correlations on cosmological parameters in the transition region is negligible in terms of cosmological parameters for WMAP; the largest relative shift seen for any parameter is 0.06σ. However, because this may not hold for other experimental setups (e.g., for different instrumental noise properties or analysis masks), but must rather be verified on a case-by-case basis, we recommend our new hybridization scheme for future experiments for statistical self-consistency reasons. Second, we use the same expression to improve the convergence rate of the Blackwell-Rao likelihood estimator, reducing the required number of Monte Carlo samples by several orders of magnitude, and thereby extend it to high-l applications.« less

Taking the Measure of the Universe: Cosmology from the WMAP Mission

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2007-01-01

The data from the first three years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature anisotropy and new full-sky maps of the polarization. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. These and other aspects of the mission will be discussed.

BOOK REVIEW: The Cosmic Microwave Background The Cosmic Microwave Background

NASA Astrophysics Data System (ADS)

Coles, Peter

2009-08-01

With the successful launch of the European Space Agency's Planck satellite earlier this year the cosmic microwave background (CMB) is once again the centre of attention for cosmologists around the globe. Since its accidental discovery in 1964 by Arno Penzias and Robert Wilson, this relic of the Big Bang has been subjected to intense scrutiny by generation after generation of experiments and has gradually yielded up answers to the deepest questions about the origin of our Universe. Most recently, the Wilkinson Microwave Anisotropy Probe (WMAP) has made a full-sky analysis of the pattern of temperature and polarization variations that helped establish a new standard cosmological model, confirmed the existence of dark matter and dark energy, and provided strong evidence that there was an epoch of primordial inflation. Ruth Durrer's book reflects the importance of the CMB for future developments in this field. Aimed at graduate students and established researchers, it consists of a basic introduction to cosmology and the theory of primordial perturbations followed by a detailed explanation of how these manifest themselves as measurable variations in the present-day radiation field. It then focuses on the statistical methods needed to obtain accurate estimates of the parameters of the standard cosmological model, and finishes with a discussion of the effect of gravitational lensing on the CMB and on the evolution of its spectrum. The book apparently grew out of various lecture notes on CMB anisotropies for graduate courses given by the author. Its level and scope are well matched to the needs of such an audience and the presentation is clear and well-organized. I am sure that this book will be a useful reference for more senior scientists too. If I have a criticism, it is not about what is in the book but what is omitted. In my view, one of the most exciting possibilities for future CMB missions, including Planck, is the possibility that they might discover physics

Microwave-assisted Chemical Transformations

EPA Science Inventory

In recent years, there has been a considerable interest in developing sustainable chemistries utilizing green chemistry principles. Since the first published report in 1986 by Gedye and Giguere on microwave assisted synthesis in household microwave ovens, the use of microwaves as...

Evaluation of multichannel Wiener filters applied to fine resolution passive microwave images of first-year sea ice

NASA Technical Reports Server (NTRS)

Full, William E.; Eppler, Duane T.

1993-01-01

The effectivity of multichannel Wiener filters to improve images obtained with passive microwave systems was investigated by applying Wiener filters to passive microwave images of first-year sea ice. Four major parameters which define the filter were varied: the lag or pixel offset between the original and the desired scenes, filter length, the number of lines in the filter, and the weight applied to the empirical correlation functions. The effect of each variable on the image quality was assessed by visually comparing the results. It was found that the application of multichannel Wiener theory to passive microwave images of first-year sea ice resulted in visually sharper images with enhanced textural features and less high-frequency noise. However, Wiener filters induced a slight blocky grain to the image and could produce a type of ringing along scan lines traversing sharp intensity contrasts.

Improved method for detecting local discontinuities in CMB data by finite differencing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowyer, Jude; Jaffe, Andrew H.

2011-01-15

An unexpected distribution of temperatures in the CMB could be a sign of new physics. In particular, the existence of cosmic defects could be indicated by temperature discontinuities via the Kaiser-Stebbins effect. In this paper, we show how performing finite differences on a CMB map, with the noise regularized in harmonic space, may expose such discontinuities, and we report the results of this process on the 7-year Wilkinson Microwave Anisotropy Probe data.

New estimates of the CMB angular power spectra from the WMAP 5 year low-resolution data

NASA Astrophysics Data System (ADS)

Gruppuso, A.; de Rosa, A.; Cabella, P.; Paci, F.; Finelli, F.; Natoli, P.; de Gasperis, G.; Mandolesi, N.

2009-11-01

A quadratic maximum likelihood (QML) estimator is applied to the Wilkinson Microwave Anisotropy Probe (WMAP) 5 year low-resolution maps to compute the cosmic microwave background angular power spectra (APS) at large scales for both temperature and polarization. Estimates and error bars for the six APS are provided up to l = 32 and compared, when possible, to those obtained by the WMAP team, without finding any inconsistency. The conditional likelihood slices are also computed for the Cl of all the six power spectra from l = 2 to 10 through a pixel-based likelihood code. Both the codes treat the covariance for (T, Q, U) in a single matrix without employing any approximation. The inputs of both the codes (foreground-reduced maps, related covariances and masks) are provided by the WMAP team. The peaks of the likelihood slices are always consistent with the QML estimates within the error bars; however, an excellent agreement occurs when the QML estimates are used as a fiducial power spectrum instead of the best-fitting theoretical power spectrum. By the full computation of the conditional likelihood on the estimated spectra, the value of the temperature quadrupole CTTl=2 is found to be less than 2σ away from the WMAP 5 year Λ cold dark matter best-fitting value. The BB spectrum is found to be well consistent with zero, and upper limits on the B modes are provided. The parity odd signals TB and EB are found to be consistent with zero.

Twenty-four year record of Northern Hemisphere snow cover derived from passive microwave remote sensing

NASA Astrophysics Data System (ADS)

Armstrong, Richard L.; Brodzik, Mary Jo

2003-04-01

Snow cover is an important variable for climate and hydrologic models due to its effects on energy and moisture budgets. Seasonal snow can cover more than 50% of the Northern Hemisphere land surface during the winter resulting in snow cover being the land surface characteristic responsible for the largest annual and interannual differences in albedo. Passive microwave satellite remote sensing can augment measurements based on visible satellite data alone because of the ability to acquire data through most clouds or during darkness as well as to provide a measure of snow depth or water equivalent. It is now possible to monitor the global fluctuation of snow cover over a 24 year period using passive microwave data (Scanning Multichannel Microwave Radiometer (SMMR) 1978-1987 and Special Sensor Microwave/Imager (SSM/I), 1987-present). Evaluation of snow extent derived from passive microwave algorithms is presented through comparison with the NOAA Northern Hemisphere snow extent data. For the period 1978 to 2002, both passive microwave and visible data sets show a smiliar pattern of inter-annual variability, although the maximum snow extents derived from the microwave data are consistently less than those provided by the visible statellite data and the visible data typically show higher monthly variability. During shallow snow conditions of the early winter season microwave data consistently indicate less snow-covered area than the visible data. This underestimate of snow extent results from the fact that shallow snow cover (less than about 5.0 cm) does not provide a scattering signal of sufficient strength to be detected by the algorithms. As the snow cover continues to build during the months of January through March, as well as on into the melt season, agreement between the two data types continually improves. This occurs because as the snow becomes deeper and the layered structure more complex, the negative spectral gradient driving the passive microwave algorithm

Concise calculation of the scaling function, exponents, and probability functional of the Edwards-Wilkinson equation with correlated noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Y.; Pang, N.; Halpin-Healy, T.

1994-12-01

The linear Langevin equation proposed by Edwards and Wilkinson [Proc. R. Soc. London A 381, 17 (1982)] is solved in closed form for noise of arbitrary space and time correlation. Furthermore, the temporal development of the full probability functional describing the height fluctuations is derived exactly, exhibiting an interesting evolution between two distinct Gaussian forms. We determine explicitly the dynamic scaling function for the interfacial width for any given initial condition, isolate the early-time behavior, and discover an invariance that was unsuspected in this problem of arbitrary spatiotemporal noise.

Microwave Discharges

NASA Astrophysics Data System (ADS)

Marec, J.; Bloyet, E.; Chaker, M.; Leprince, P.; Nghiem, P.

Microwave discharges first appeared as unwanted and disturbing effects. However, beginning about the end of World War II, Professors Allis and Brown at the Massachusetts Institute of Technology started to investigate the physics of these discharges. During the next few years, many experimental and theoretical studies were undertaken. However, in the early 60's and for about 15 years, there were few studies of such discharges because of the theoretical difficulties encountered. Effectively, the impossibility of modeling microwave discharges prevented a good understanding of their behavior, and their future use did not appear promising. Recently there has been new interest in these discharges. The plasmas produced by microwave discharges find applications in areas such as: 1) spectroscopy (because of their low contamination), and 2) plasma chemistry. Another advantage of these discharges as compared to d.c. discharges is their ease of operation.

NSIDC's passive microwave satellite record: The story behind 30 years of data across multiple satellite platforms

NASA Astrophysics Data System (ADS)

Scott, D. J.; Brandt, M.; Savoie, M. H.; Stewart, J. S.

2016-12-01

The National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) has been producing and distributing passive microwave snow and ice data sets from the Special Sensor Microwave Imager (SSM/I) and Special Sensor Microwave Imager/Sounder (SSMIS) for over two decades. Aboard the Defense Meteorological Satellite Program (DMSP) platforms, SSM/I and SSMIS have been operating across eight different orbiting DMSP satellites since 1987, providing an invaluable 30 year record for snow and ice climate data studies. Each sensor has performed within or beyond its expected life cycle, ultimately resulting in a transition across platforms to continue the data record. On occasion the satellites have failed unexpectedly, requiring an unplanned need for science and data management to come together and adjust production code and services to get the data back online in a timely fashion. In recent years, this has become a greater importance as climate blogging sites have increased the visibility of near-real-time passive microwave products to communicate the current changes in the Polar Regions. This presentation summarizes the history and most recent activities surrounding satellite transitions, including the scientific assessment and development required in maintaining a streamlined data record across multiple sensors. In addition, we examine challenges in long-term provenance as well as the considerations and decisions made based on value added products utilizing these data, as well as cryospheric research and general public needs.

Stable indications of relic gravitational waves in Wilkinson Microwave Anisotropy Probe data and forecasts for the Planck mission

NASA Astrophysics Data System (ADS)

Zhao, W.; Baskaran, D.; Grishchuk, L. P.

2009-10-01

The relic gravitational waves are the cleanest probe of the violent times in the very early history of the Universe. They are expected to leave signatures in the observed cosmic microwave background anisotropies. We significantly improved our previous analysis [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. DPRVDAQ1550-7998 79, 023002 (2009)10.1103/PhysRevD.79.023002] of the 5-year WMAP TT and TE data at lower multipoles ℓ. This more general analysis returned essentially the same maximum likelihood result (unfortunately, surrounded by large remaining uncertainties): The relic gravitational waves are present and they are responsible for approximately 20% of the temperature quadrupole. We identify and discuss the reasons by which the contribution of gravitational waves can be overlooked in a data analysis. One of the reasons is a misleading reliance on data from very high multipoles ℓ and another a too narrow understanding of the problem as the search for B modes of polarization, rather than the detection of relic gravitational waves with the help of all correlation functions. Our analysis of WMAP5 data has led to the identification of a whole family of models characterized by relatively high values of the likelihood function. Using the Fisher matrix formalism we formulated forecasts for Planck mission in the context of this family of models. We explore in detail various “optimistic,” “pessimistic,” and “dream case” scenarios. We show that in some circumstances the B-mode detection may be very inconclusive, at the level of signal-to-noise ratio S/N=1.75, whereas a smarter data analysis can reveal the same gravitational wave signal at S/N=6.48. The final result is encouraging. Even under unfavorable conditions in terms of instrumental noises and foregrounds, the relic gravitational waves, if they are characterized by the maximum likelihood parameters that we found from WMAP5 data, will be detected by Planck at the level S/N=3.65.

The Cosmic Microwave Background Anisotropy

NASA Astrophysics Data System (ADS)

Bennett, C. L.

1994-12-01

The properties of the cosmic microwave background radiation provide unique constraints on the history and evolution of the universe. The first detection of anisotropy of the microwave radiation was reported by the COBE Team in 1992, based on the first year of flight data. The latest analyses of the first two years of COBE data are reviewed in this talk, including the amplitude of the microwave anisotropy as a function of angular scale and the statistical nature of the fluctuations. The two-year results are generally consistent with the earlier first year results, but the additional data allow for a better determination of the key cosmological parameters. In this talk the COBE results are compared with other observational anisotropy results and directions for future cosmic microwave anisotropy observations will be discussed. The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). Scientific guidance is provided by the COBE Science Working Group.

Taking the Measure of the Universe: Cosmology from the WMAP Mission

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2003-01-01

The data from the first year of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide the first detailed full sky map of the cosmic microwave background radiation. The anisotropy in the radiation temperature provides a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. These and other aspects of the mission will be discussed. The WMAP satellite was built in a close partnership between Princeton University and the Goddard Space Flight Center.

Microwave furnace having microwave compatible dilatometer

DOEpatents

Kimrey, Jr., Harold D.; Janney, Mark A.; Ferber, Mattison K.

1992-01-01

An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy.

Microwave furnace having microwave compatible dilatometer

DOEpatents

Kimrey, H.D. Jr.; Janney, M.A.; Ferber, M.K.

1992-03-24

An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy. 2 figs.

Cosmological parameters from a re-analysis of the WMAP 7 year low-resolution maps

NASA Astrophysics Data System (ADS)

Finelli, F.; De Rosa, A.; Gruppuso, A.; Paoletti, D.

2013-06-01

Cosmological parameters from Wilkinson Microwave Anisotropy Probe (WMAP) 7 year data are re-analysed by substituting a pixel-based likelihood estimator to the one delivered publicly by the WMAP team. Our pixel-based estimator handles exactly intensity and polarization in a joint manner, allowing us to use low-resolution maps and noise covariance matrices in T, Q, U at the same resolution, which in this work is 3.6°. We describe the features and the performances of the code implementing our pixel-based likelihood estimator. We perform a battery of tests on the application of our pixel-based likelihood routine to WMAP publicly available low-resolution foreground-cleaned products, in combination with the WMAP high-ℓ likelihood, reporting the differences on cosmological parameters evaluated by the full WMAP likelihood public package. The differences are not only due to the treatment of polarization, but also to the marginalization over monopole and dipole uncertainties present in the WMAP pixel likelihood code for temperature. The credible central value for the cosmological parameters change below the 1σ level with respect to the evaluation by the full WMAP 7 year likelihood code, with the largest difference in a shift to smaller values of the scalar spectral index nS.

WMAP Observatory Thermal Design and On-Orbit Thermal Performance

NASA Technical Reports Server (NTRS)

Glazer, Stuart D.; Brown, Kimberly D.; Michalek, Theodore J.; Ancarrow, Walter C.

2003-01-01

The Wilkinson Microwave Anisotropy Probe (WMAP) observatory, launched June 30, 2001, is designed to measure the cosmic microwave background radiation with unprecedented precision and accuracy while orbiting the second Lagrange point (L2). The instrument cold stage must be cooled passively to <95K, and systematic thermal variations in selected instrument components controlled to less than 0.5 mK (rms) per spin period. This paper describes the thermal design and testing of the WMAP spacecraft and instrument. Flight thermal data for key spacecraft and instrument components are presented from launch through the first year of mission operations. Effects of solar flux variation due to the Earth's elliptical orbit about the sun, surface thermo-optical property degradations, and solar flares on instrument thermal stability are discussed.

Microwave Sensors for Breast Cancer Detection

PubMed Central

2018-01-01

Breast cancer is the leading cause of death among females, early diagnostic methods with suitable treatments improve the 5-year survival rates significantly. Microwave breast imaging has been reported as the most potential to become the alternative or additional tool to the current gold standard X-ray mammography for detecting breast cancer. The microwave breast image quality is affected by the microwave sensor, sensor array, the number of sensors in the array and the size of the sensor. In fact, microwave sensor array and sensor play an important role in the microwave breast imaging system. Numerous microwave biosensors have been developed for biomedical applications, with particular focus on breast tumor detection. Compared to the conventional medical imaging and biosensor techniques, these microwave sensors not only enable better cancer detection and improve the image resolution, but also provide attractive features such as label-free detection. This paper aims to provide an overview of recent important achievements in microwave sensors for biomedical imaging applications, with particular focus on breast cancer detection. The electric properties of biological tissues at microwave spectrum, microwave imaging approaches, microwave biosensors, current challenges and future works are also discussed in the manuscript. PMID:29473867

Microwave Sensors for Breast Cancer Detection.

PubMed

Wang, Lulu

2018-02-23

Breast cancer is the leading cause of death among females, early diagnostic methods with suitable treatments improve the 5-year survival rates significantly. Microwave breast imaging has been reported as the most potential to become the alternative or additional tool to the current gold standard X-ray mammography for detecting breast cancer. The microwave breast image quality is affected by the microwave sensor, sensor array, the number of sensors in the array and the size of the sensor. In fact, microwave sensor array and sensor play an important role in the microwave breast imaging system. Numerous microwave biosensors have been developed for biomedical applications, with particular focus on breast tumor detection. Compared to the conventional medical imaging and biosensor techniques, these microwave sensors not only enable better cancer detection and improve the image resolution, but also provide attractive features such as label-free detection. This paper aims to provide an overview of recent important achievements in microwave sensors for biomedical imaging applications, with particular focus on breast cancer detection. The electric properties of biological tissues at microwave spectrum, microwave imaging approaches, microwave biosensors, current challenges and future works are also discussed in the manuscript.

Active microwave water equivalence

NASA Technical Reports Server (NTRS)

Boyne, H. S.; Ellerbruch, D. A.

1980-01-01

Measurements of water equivalence using an active FM-CW microwave system were conducted over the past three years at various sites in Colorado, Wyoming, and California. The measurement method is described. Measurements of water equivalence and stratigraphy are compared with ground truth. A comparison of microwave, federal sampler, and snow pillow measurements at three sites in Colorado is described.

HARMONIC IN-PAINTING OF COSMIC MICROWAVE BACKGROUND SKY BY CONSTRAINED GAUSSIAN REALIZATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jaiseung; Naselsky, Pavel; Mandolesi, Nazzareno, E-mail: jkim@nbi.dk

The presence of astrophysical emissions between the last scattering surface and our vantage point requires us to apply a foreground mask on cosmic microwave background (CMB) sky maps, leading to large cuts around the Galactic equator and numerous holes. Since many CMB analysis, in particular on the largest angular scales, may be performed on a whole-sky map in a more straightforward and reliable manner, it is of utmost importance to develop an efficient method to fill in the masked pixels in a way compliant with the expected statistical properties and the unmasked pixels. In this Letter, we consider the Montemore » Carlo simulation of a constrained Gaussian field and derive it CMB anisotropy in harmonic space, where a feasible implementation is possible with good approximation. We applied our method to simulated data, which shows that our method produces a plausible whole-sky map, given the unmasked pixels, and a theoretical expectation. Subsequently, we applied our method to the Wilkinson Microwave Anisotropy Probe foreground-reduced maps and investigated the anomalous alignment between quadrupole and octupole components. From our investigation, we find that the alignment in the foreground-reduced maps is even higher than the Internal Linear Combination map. We also find that the V-band map has higher alignment than other bands, despite the expectation that the V-band map has less foreground contamination than other bands. Therefore, we find it hard to attribute the alignment to residual foregrounds. Our method will be complementary to other efforts on in-painting or reconstructing the masked CMB data, and of great use to Planck surveyor and future missions.« less

Microwave power - An energy transmission alternative for the year 2000

NASA Technical Reports Server (NTRS)

Nalos, E.; Sperber, R.

1980-01-01

Recent technological advances related to the feasibility of efficient RF-dc rectification make it likely that by the year 2000 the transmission of power through space will have become a practical reality. Proposals have been made to power helicopters, aircraft, balloons, and rockets remotely. Other proposals consider the transfer of power from point to point on earth via relay through space or a transmission of power from large power sources in space. Attention has also been given to possibilities regarding the transmission of power between various points in the solar system. An outline is provided of the microwave power transmission system envisaged for the solar power satellite, taking into account the transmitting antenna, the receiver on earth, aspects of beam formation and control, transmitter options, the receiving antenna design, and cost and efficiency considerations.

Large-angle correlations in the cosmic microwave background

NASA Astrophysics Data System (ADS)

Efstathiou, George; Ma, Yin-Zhe; Hanson, Duncan

2010-10-01

It has been argued recently by Copi et al. 2009 that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, inflationary Lambda cold dark matter (ΛCDM) cosmology. We compare various estimators of the temperature correlation function showing how they depend on assumptions of statistical isotropy and how they perform on the Wilkinson Microwave Anisotropy Probe (WMAP) 5-yr Internal Linear Combination (ILC) maps with and without a sky cut. We show that the low multipole harmonics that determine the large-scale features of the temperature correlation function can be reconstructed accurately from the data that lie outside the sky cuts. The reconstructions are only weakly dependent on the assumed statistical properties of the temperature field. The temperature correlation functions computed from these reconstructions are in good agreement with those computed from the ILC map over the whole sky. We conclude that the large-scale angular correlation function for our realization of the sky is well determined. A Bayesian analysis of the large-scale correlations is presented, which shows that the data cannot exclude the standard ΛCDM model. We discuss the differences between our results and those of Copi et al. Either there exists a violation of statistical isotropy as claimed by Copi et al., or these authors have overestimated the significance of the discrepancy because of a posteriori choices of estimator, statistic and sky cut.

Statistics and topology of the COBE differential microwave radiometer first-year sky maps

NASA Technical Reports Server (NTRS)

Smoot, G. F.; Tenorio, L.; Banday, A. J.; Kogut, A.; Wright, E. L.; Hinshaw, G.; Bennett, C. L.

1994-01-01

We use statistical and topological quantities to test the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) first-year sky maps against the hypothesis that the observed temperature fluctuations reflect Gaussian initial density perturbations with random phases. Recent papers discuss specific quantities as discriminators between Gaussian and non-Gaussian behavior, but the treatment of instrumental noise on the data is largely ignored. The presence of noise in the data biases many statistical quantities in a manner dependent on both the noise properties and the unknown cosmic microwave background temperature field. Appropriate weighting schemes can minimize this effect, but it cannot be completely eliminated. Analytic expressions are presented for these biases, and Monte Carlo simulations are used to assess the best strategy for determining cosmologically interesting information from noisy data. The genus is a robust discriminator that can be used to estimate the power-law quadrupole-normalized amplitude, Q(sub rms-PS), independently of the two-point correlation function. The genus of the DMR data is consistent with Gaussian initial fluctuations with Q(sub rms-PS) = (15.7 +/- 2.2) - (6.6 +/- 0.3)(n - 1) micro-K, where n is the power-law index. Fitting the rms temperature variations at various smoothing angles gives Q(sub rms-PS) = 13.2 +/- 2.5 micro-K and n = 1.7(sup (+0.3) sub (-0.6)). While consistent with Gaussian fluctuations, the first year data are only sufficient to rule out strongly non-Gaussian distributions of fluctuations.

Constraints on isocurvature models from the WMAP first-year data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moodley, K.; Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH; Bucher, M.

2004-11-15

We investigate the constraints imposed by the first-year Wilkinson Microwave Anisotropy Probe (WMAP) cosmic microwave background (CMB) data extended to higher multipoles by data from ACBAR, BOOMERANG, CBI, and the VSA and by the large-scale structure data from the 2dF galaxy redshift survey on the possible amplitude of primordial isocurvature modes. A flat universe with cold dark matter (CDM) and cosmological constant {lambda} is assumed, and the baryon, CDM isocurvature (CI), and neutrino density (NID), and velocity (NIV) isocurvature modes are considered. Constraints on the allowed isocurvature contributions are established from the data for various combinations of the adiabatic modemore » and one, two, and three isocurvature modes, with intermode cross correlations allowed. Since baryon and CDM isocurvature are observationally virtually indistinguishable, these modes are not considered separately. We find that when just a single isocurvature mode is added, the present data allows an isocurvature fraction, in terms of the nonadiabatic contribution to the power in the CMB anisotropy, as large as 13{+-}6, 7{+-}4, and 13{+-}7 percent for adiabatic plus the CI, NID, and NIV modes, respectively. When two isocurvature modes plus the adiabatic mode and cross correlations are allowed, these percentages rise to 47{+-}16, 34{+-}12, and 44{+-}12 for the combinations CI+NID, CI+NIV, and NID+NIV, respectively. Finally, when all three isocurvature modes and cross correlations are allowed, the admissible isocurvature fraction rises to 57{+-}9 percent. In our analysis we consider only scalar modes with a single common tilt parameter for all the modes and do not consider any possible primordial anisotropies in the local neutrino velocity distribution beyond quadrupole order. The sensitivity of the results to the choice of prior probability distribution is examined.« less

Percutaneous microwave ablation of renal cell carcinoma using a high power microwave system: focus upon safety and efficacy.

PubMed

Filippiadis, D K; Gkizas, C; Chrysofos, M; Siatelis, A; Velonakis, G; Alexopoulou, E; Kelekis, A; Brountzos, E; Kelekis, N

2017-12-04

Percutaneous ablation is an expanding, minimally invasive approach for small- to medium-sized renal masses. The purpose of this study is to review safety, and mid-term efficacy of percutaneous microwave ablation (MWA) for Renal Cell Carcinoma (RCC) treatment using a high power microwave system. Institutional database research identified 50 consecutive patients with a single lesion resembling renal cell carcinoma in CT and MRI who underwent percutaneous microwave ablation using a high power microwave system. All patients underwent biopsy on the same session with ablation using an 18G semi-automatic soft tissue biopsy needle. Contrast-enhanced computed tomography or magnetic resonance imaging was used for post-ablation follow-up. Patient and tumour characteristics, microwave technique, complications and pattern of recurrence were evaluated. Mean patient age was 74 years (male-female: 31-19). Average lesion size was 3.1 cm (range 2.0-4.3 cm). Biopsy results report RCC (n = 48), inflammatory myofibroblastic tumour (n = 1), and non-diagnostic sample (n = 1). The 3-year overall survival was 95.8% (46/48). Two patients died during the 3-year follow-up period due to causes unrelated to the MW ablation and to the RCC. Minor complications including haematomas requiring nothing but observation occurred at 4% (2/50) of the cases. Local recurrence of 6.25% (3/48) was observed with 2/3 cases being re-treated achieving a total clinical success of 97.9% (47/48 lesions). Percutaneous microwave ablation of RCC using a high power microwave system is a safe and efficacious technique for the treatment of small- to medium-sized renal masses.

Development of a microwave clothes dryer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-07-01

The objective of the project is to investigate the microwave drying of clothes and to produce an impartial, generic database for use by interested parties, including appliance manufacturers, who may want to use it when designing and developing microwave clothes dryers. This interim report covers the first year of activity on the project. During that time, a laboratory test model of a microwave clothes dryer was constructed and tested over a wide range of parameters. The test unit was the same size as a residential home dryer and had eight 0.85-kW microwave power supplies from home ovens and a 5-kWmore » resistance air heater. Thus, the model could be used for microwave drying, hot air drying or for a combination of both drying techniques. Microwave drying was effective in three drying modes: Cool drying, fast drying and very efficient drying. Microwaves penetrate the clothes and heat the water molecules directly while conventional heat energy must be conducted through the clothes to evaporate the water. In cool drying, microwaves alone heat the water and an airflow of slightly warmed air carries away the moisture. In fast drying, the microwave power is combined with hot air drying to reduce drying times by as much as 50%. In the most efficient mode of drying, microwave power is used along with the waste heat from the microwave power supply. Hazards testing and fine fabric tests are scheduled for the future.« less

Microwave photonics with superconducting quantum circuits

NASA Astrophysics Data System (ADS)

Gu, Xiu; Kockum, Anton Frisk; Miranowicz, Adam; Liu, Yu-xi; Nori, Franco

2017-11-01

In the past 20 years, impressive progress has been made both experimentally and theoretically in superconducting quantum circuits, which provide a platform for manipulating microwave photons. This emerging field of superconducting quantum microwave circuits has been driven by many new interesting phenomena in microwave photonics and quantum information processing. For instance, the interaction between superconducting quantum circuits and single microwave photons can reach the regimes of strong, ultra-strong, and even deep-strong coupling. Many higher-order effects, unusual and less familiar in traditional cavity quantum electrodynamics with natural atoms, have been experimentally observed, e.g., giant Kerr effects, multi-photon processes, and single-atom induced bistability of microwave photons. These developments may lead to improved understanding of the counterintuitive properties of quantum mechanics, and speed up applications ranging from microwave photonics to superconducting quantum information processing. In this article, we review experimental and theoretical progress in microwave photonics with superconducting quantum circuits. We hope that this global review can provide a useful roadmap for this rapidly developing field.

PREDICTING CORAL BLEACHING IN RESPONSE TO ENVIRONMENTAL STRESSORS USING 8 YEARS OF GLOBAL-SCALE DATA.

EPA Science Inventory

Coral reefs are among the most diverse marine ecosystems on the planet (Wilkinson 2002), but have experienced extensive mortality over the past few decades as a result of mass bleaching events (Hoegh-Guldberg 1999, Wilkinson 2002, Hughes 2003, Obura 2005). Historically, elevated...

Microwave Absorption Characteristics of Tire

NASA Astrophysics Data System (ADS)

Zhang, Yuzhe; Hwang, Jiann-Yang; Peng, Zhiwei; Andriese, Matthew; Li, Bowen; Huang, Xiaodi; Wang, Xinli

The recycling of waste tires has been a big environmental problem. About 280 million waste tires are produced annually in the United States and more than 2 billion tires are stockpiled, which cause fire hazards and health issues. Tire rubbers are insoluble elastic high polymer materials. They are not biodegradable and may take hundreds of years to decompose in the natural environment. Microwave irradiation can be a thermal processing method for the decomposition of tire rubbers. In this study, the microwave absorption properties of waste tire at various temperatures are characterized to determine the conditions favorable for the microwave heating of waste tires.

Coupled microwave/photoassisted methods for environmental remediation.

PubMed

Horikoshi, Satoshi; Serpone, Nick

2014-11-05

The microwave-induced acceleration of photocatalytic reactions was discovered serendipitously in the late 1990s. The activity of photocatalysts is enhanced significantly by both microwave radiation and UV light. Particularly relevant, other than as a heat source, was the enigmatic phenomenon of the non-thermal effect(s) of the microwave radiation that facilitated photocatalyzed reactions, as evidenced when examining various model contaminants in aqueous media. Results led to an examination of the possible mechanism(s) of the microwave effect(s). In the present article we contend that the microwaves' non-thermal effect(s) is an important factor in the enhancement of TiO2-photoassisted reactions involving the decomposition of organic pollutants in model wastewaters by an integrated (coupled) microwave-/UV-illumination method (UV/MW). Moreover, such coupling of no less than two irradiation methods led to the fabrication and ultimate investigation of microwave discharged electrodeless lamps (MDELs) as optimal light sources; their use is also described. The review focuses on the enhanced activity of photocatalytic reactions when subjected to microwave radiation and concentrates on the authors' research of the past few years.

Ocular surface injury from a microwave superheated liquid.

PubMed

Gagnon, Michael R; Walter, Keith A

2004-03-01

To describe the ocular surface injury resulting from a microwave superheated liquid. Case report. A 40-year-old man sustained an ocular surface injury from a microwave superheated liquid. The injury resulted in limbal stem cell damage requiring an autograft limbal stem cell transplantation. We are unaware of previous reports of microwave superheated liquids resulting in ocular injury. Microwave superheating of liquids is a potential ocular danger that should be brought to the attention of both ophthalmologists and their patients.

Results from two years of ozone data taken with a new, ground-based microwave instrument: An overview

NASA Technical Reports Server (NTRS)

Parrish, A.; Connor, B. J.; Tsou, J. J.; Mcdermid, I. S.; Chu, W. P.; Siskind, D. E.

1994-01-01

An overview of two years of data obtained with a ground-based microwave instrument is given. Intercomparisons with data obtained by the co-located JPL lidar and by SAGE 2 during near overpasses of the site are discussed, as are comparisons with mesospheric data taken earlier by SME and LIMS. Observations of diurnal variations of mesospheric ozone are shown.

Microwave Treatment of Prostate Cancer and Hyperplasia

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey; Ngo, Phong; Carl, J. R.; Raffoul, George

2005-01-01

Microwave ablation in the form of microwave energy applied to a heart muscle by a coaxial catheter inserted in a vein in the groin area can be used to heat and kill diseased heart cells. A microwave catheter has been developed to provide deep myocardial ablation to treat ventricular tachycardia by restoring appropriate electrical activity within the heart and eliminating irregular heartbeats. The resulting microwave catheter design, which is now being developed for commercial use in treating ventricular tachycardia, can be modified to treat prostate cancer and benign prostatic hyperplasia (BPH). Inasmuch as the occurrence of BPH is increasing currently 350,000 operations per year are performed in the United States alone to treat this condition this microwave catheter has significant commercial potential.

Microwave-assisted ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bechtold, J.K.; Booty, M.R.; Kriegsmann, G.A.

1996-12-31

In recent years, microwave heating has been proposed as an alternative to ignite materials during the process of self-propagating high-temperature synthesis. The microwave heating and ignition of a combustible material is modeled and analyzed in the small Biot number and large activation energy regimes. Both the temporal and spatial evolution of the temperature within the material are described. The ignition characteristics are determined by a localized equation for the perturbation to the inert temperature, which is shown to exhibit thermal runaway behavior. Analysis of this local equation provides explicit ignition conditions in terms of the physical parameters in the problem.

Inhalation trauma due to overheating in a microwave oven.

PubMed Central

Zanen, A L; Rietveld, A P

1993-01-01

The microwave oven is a kitchen appliance that has become increasingly popular in recent years. In some instances the temperature in the microwave oven can become exceedingly high. A case is discussed of a patient with respiratory distress after inhalation of gas from an overheated microwave oven. Images PMID:8497834

Nonthermal microwave effects revisited: on the importance of internal temperature monitoring and agitation in microwave chemistry.

PubMed

Herrero, M Antonia; Kremsner, Jennifer M; Kappe, C Oliver

2008-01-04

The concept of nonthermal microwave effects has received considerable attention in recent years and is the subject of intense debate in the scientific community. Nonthermal microwave effects have been postulated to result from a direct stabilizing interaction of the electric field with specific (polar) molecules in the reaction medium that is not related to a macroscopic temperature effect. In order to probe the existence of nonthermal microwave effects, four synthetic transformations (Diels-Alder cycloaddition, alkylation of triphenylphosphine and 1,2,4-triazole, direct amide bond formation) were reevaluated under both microwave dielectric heating and conventional thermal heating. In all four cases, previous studies have claimed the existence of nonthermal microwave effects in these reactions. Experimentally, significant differences in conversion and/or product distribution comparing the conventionally and microwave-heated experiments performed at the same measured reaction temperature were found. The current reevaluation of these reactions was performed in a dedicated reactor setup that allowed accurate internal reaction temperature measurements using a multiple fiber-optic probe system. Using this technology, the importance of efficient stirring and internal temperature measurement in microwave-heated reactions was made evident. Inefficient agitation leads to temperature gradients within the reaction mixture due to field inhomogeneities in the microwave cavity. Using external infrared temperature sensors in some cases results in significant inaccuracies in the temperature measurement. Applying the fiber-optic probe temperature monitoring device, a critical reevaluation of all four reactions has provided no evidence for the existence of nonthermal microwave effects. Ensuring efficient agitation of the reaction mixture via magnetic stirring, no significant differences in terms of conversion and selectivity between experiments performed under microwave or oil bath

Integrated Sachs-Wolfe effect from the cross correlation of WMAP 3year and the NRAO VLA sky survey data: New results and constraints on dark energy

NASA Astrophysics Data System (ADS)

Pietrobon, Davide; Balbi, Amedeo; Marinucci, Domenico

2006-08-01

We cross correlate the new 3 year Wilkinson Microwave Anistropy Probe (WMAP) cosmic microwave background data with the NRAO VLA Sky Survey radio galaxy data and find further evidence of late integrated Sachs-Wolfe (ISW) effect taking place at late times in cosmic history. Our detection makes use of a novel statistical method (P. Baldi, G. Kerkyacharian, D. Marinucci, and D. Picard, math.ST/0606154 and P. Baldi, G. Kerkyacharian, D. Marinucci, D. Picard, math.ST/0606599) based on a new construction of spherical wavelets, called needlets. The null hypothesis (no ISW) is excluded at more than 99.7% confidence. When we compare the measured cross correlation with the theoretical predictions of standard, flat cosmological models with a generalized dark energy component parameterized by its density, ΩDE, equation of state w and speed of sound cs2, we find 0.3≤ΩDE≤0.8 at 95% C.L., independently of cs2 and w. If dark energy is assumed to be a cosmological constant (w=-1), the bound on density shrinks to 0.41≤ΩDE≤0.79. Models without dark energy are excluded at more than 4σ. The bounds on w depend rather strongly on the assumed value of cs2. We find that models with more negative equation of state (such as phantom models) are a worse fit to the data in the case cs2=1 than in the case cs2=0.

Facial burns from exploding microwaved foods: Case series and review.

PubMed

Bagirathan, Shenbana; Rao, Krishna; Al-Benna, Sammy; O'Boyle, Ciaran P

2016-03-01

Microwave ovens allow for quick and simple cooking. However, the importance of adequate food preparation, prior to microwave cooking, and the consequences of inadequate preparation are not well-known. The authors conducted a retrospective outcome analysis of all patients who sustained facial burns from microwaved foods and were treated at a UK regional burns unit over a six-year period. Patients were identified from clinical records. Eight patients presented following inadequate preparation of either tinned potatoes (n=4) or eggs (n=4). All patients sustained <2% total body surface area facial burns. Mean age was 41 years (range 21-68 years). Six cases (75%) had associated ocular injury. One received amniotic membrane grafts; this individual's vision remains poor twelve months after injury. Rapid dielectric heating of water within foods may produce high steam and vapour pressure gradients and cause explosive decompression [1,5,11]. Consumers may fail to recognise differential heating and simply cook foods for longer if they remain cool on the outer surface. Education on safe use and risks of microwave-cooked foods may help prevent these potentially serious injuries. Microwave ovens have become ubiquitous. The authors recognise the need for improved public awareness of safe microwave cooking. Burns resulting from microwave-cooked foods may have life-changing consequences. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Microwave Brightness Of Land Surfaces From Outer Space

NASA Technical Reports Server (NTRS)

Kerr, Yann H.; Njoku, Eni G.

1991-01-01

Mathematical model approximates microwave radiation emitted by land surfaces traveling to microwave radiometer in outer space. Applied to measurements made by Scanning Multichannel Microwave Radiometer (SMMR). Developed for interpretation of microwave imagery of Earth to obtain distributions of various chemical, physical, and biological characteristics across its surface. Intended primarily for use in mapping moisture content of soil and fraction of Earth covered by vegetation. Advanced Very-High-Resolution Radiometer (AVHRR), provides additional information on vegetative cover, thereby making possible retrieval of soil-moisture values from SMMR measurements. Possible to monitor changes of land surface during intervals of 5 to 10 years, providing significant data for mathematical models of evolution of climate.

Mapping the cosmos

NASA Astrophysics Data System (ADS)

Clery, Daniel

2009-04-01

For the last seven years, NASA's Wilkinson Microwave Anisotropy Probe (WMAP) has kept a lonely vigil in an area in space some 1.5 million kilometres further out from the Sun beyond the Earth. Known as Lagrange point L2, it is where a space probe can usefully hover, little disturbed by stray signals from home and without having to use much fuel to keep it in position. But WMAP will soon have company: two groundbreaking missions from the European Space Agency (ESA), due to be launched on the same Ariane-5 rocket later this month, will take up their positions next to NASA's craft.

Ocular surface injury from a microwave superheated egg resulting in a pseudopterygium.

PubMed

Gagnon, Michael R; Dickinson, Paul J

2005-05-01

To describe the first case of ocular surface injury resulting in a pseudopterygium from a microwave superheated egg. Case report. A 12-year-old girl sustained an ocular surface injury resulting in a pseudopterygium from a microwave superheated egg. Microwave superheated eggs can result in ocular injury. This case illustrates the potential ocular danger involved with microwave ovens.

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.

2009-01-01

Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles.

Aquarius L-Band Microwave Radiometer: Three Years of Radiometric Performance and Systematic Effects

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Hong, Liang; Pellerano, Fernando A.

2015-01-01

The Aquarius L-band microwave radiometer is a three-beam pushbroom instrument designed to measure sea surface salinity. Results are analyzed for performance and systematic effects over three years of operation. The thermal control system maintains tight temperature stability promoting good gain stability. The gain spectrum exhibits expected orbital variations with 1f noise appearing at longer time periods. The on-board detection and integration scheme coupled with the calibration algorithm produce antenna temperatures with NEDT 0.16 K for 1.44-s samples. Nonlinearity is characterized before launch and the derived correction is verified with cold-sky calibration data. Finally, long-term drift is discovered in all channels with 1-K amplitude and 100-day time constant. Nonetheless, it is adeptly corrected using an exponential model.

WMAP - A Glimpse of the Early Universe

NASA Technical Reports Server (NTRS)

Wollack, Edward

2009-01-01

The early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the "Big Bang" and the signature of the evolution of its contents. By exploiting these clues, precise constraints on the age, mass density, and geometry of the early Universe can be derived. The history of this intriguing cosmological detective story will be reviewed. Recent results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) will be presented.

A monolithic integrated photonic microwave filter

NASA Astrophysics Data System (ADS)

Fandiño, Javier S.; Muñoz, Pascual; Doménech, David; Capmany, José

2017-02-01

Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors.

Review on Microwave-Matter Interaction Fundamentals and Efficient Microwave-Associated Heating Strategies

PubMed Central

Sun, Jing; Wang, Wenlong; Yue, Qinyan

2016-01-01

Microwave heating is rapidly emerging as an effective and efficient tool in various technological and scientific fields. A comprehensive understanding of the fundamentals of microwave–matter interactions is the precondition for better utilization of microwave technology. However, microwave heating is usually only known as dielectric heating, and the contribution of the magnetic field component of microwaves is often ignored, which, in fact, contributes greatly to microwave heating of some aqueous electrolyte solutions, magnetic dielectric materials and certain conductive powder materials, etc. This paper focuses on this point and presents a careful review of microwave heating mechanisms in a comprehensive manner. Moreover, in addition to the acknowledged conventional microwave heating mechanisms, the special interaction mechanisms between microwave and metal-based materials are attracting increasing interest for a variety of metallurgical, plasma and discharge applications, and therefore are reviewed particularly regarding the aspects of the reflection, heating and discharge effects. Finally, several distinct strategies to improve microwave energy utilization efficiencies are proposed and discussed with the aim of tackling the energy-efficiency-related issues arising from the application of microwave heating. This work can present a strategic guideline for the developed understanding and utilization of the microwave heating technology. PMID:28773355

Microwave detector

DOEpatents

Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

1985-02-08

A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Estimation of primordial spectrum with post-WMAP 3-year data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafieloo, Arman; Souradeep, Tarun

2008-07-15

In this paper we implement an improved (error-sensitive) Richardson-Lucy deconvolution algorithm on the measured angular power spectrum from the Wilkinson Microwave Anisotropy Probe (WMAP) 3 year data to determine the primordial power spectrum assuming different points in the cosmological parameter space for a flat {lambda}CDM cosmological model. We also present the preliminary results of the cosmological parameter estimation by assuming a free form of the primordial spectrum, for a reasonably large volume of the parameter space. The recovered spectrum for a considerably large number of the points in the cosmological parameter space has a likelihood far better than a 'bestmore » fit' power law spectrum up to {delta}{chi}{sub eff}{sup 2}{approx_equal}-30. We use discrete wavelet transform (DWT) for smoothing the raw recovered spectrum from the binned data. The results obtained here reconfirm and sharpen the conclusion drawn from our previous analysis of the WMAP 1st year data. A sharp cut off around the horizon scale and a bump after the horizon scale seem to be a common feature for all of these reconstructed primordial spectra. We have shown that although the WMAP 3 year data prefers a lower value of matter density for a power law form of the primordial spectrum, for a free form of the spectrum, we can get a very good likelihood to the data for higher values of matter density. We have also shown that even a flat cold dark matter model, allowing a free form of the primordial spectrum, can give a very high likelihood fit to the data. Theoretical interpretation of the results is open to the cosmology community. However, this work provides strong evidence that the data retains discriminatory power in the cosmological parameter space even when there is full freedom in choosing the primordial spectrum.« less

Rocket experiment METS Microwave Energy Transmission in Space

NASA Astrophysics Data System (ADS)

Kaya, N.; Matsumoto, H.; Akiba, R.

A METS (Microwave Energy Transmission in Space) rocket experiment is being planned by the SPS (Solar Power Satellite) Working Group at the Institute of Space and Astronautical Science (ISAS) in Japan for the forthcoming International Space Year (ISY), 1992. The METS experiment is an advanced version of our MINIX rocket experiment. This paper describes the conceptual design for the METS rocket experiment. Aims are to verify the feasibility of a newly developed microwave energy transmission system designed for use in space and to study nonlinear effects of the microwave energy beam on space plasma. A high power microwave (936 W) will be transmitted by a new phase-array antenna from a mother rocket to a separate target (daughter rocket) through the Earth's ionospheric plasma. The active phased-array system has the capability of being able to focus the microwave energy at any spatial point by individually controlling the digital phase shifters.

Rocket experiment METS - Microwave Energy Transmission in Space

NASA Astrophysics Data System (ADS)

Kaya, N.; Matsumoto, H.; Akiba, R.

A Microwave Energy Transmission in Space (METS) rocket experiment is being planned by the Solar Power Satellite Working Group at the Institute of Space and Astronautical Science in Japan for the forthcoming International Space Year, 1992. The METS experiment is an advanced version of the previous MINIX rocket experiment (Matsumoto et al., 1990). This paper describes a conceptual design of the METS rocket experiment. It aims at verifying a newly developed microwave energy transmission system for space use and to study nonlinear effects of the microwave energy beam in the space plasma environment. A high power microwave of 936 W will be transmitted by the new phased-array antenna from a mother rocket to a separated target (daughter rocket) through the ionospheric plasma. The active phased-array system has a capability of focusing the microwave energy around any spatial point by controlling the digital phase shifters individually.

Microwave remote sensing of sea ice in the AIDJEX Main Experiment

USGS Publications Warehouse

Campbell, W.J.; Wayenberg, J.; Ramseyer, J.B.; Ramseier, R.O.; Vant, M.R.; Weaver, R.; Redmond, A.; Arsenaul, L.; Gloersen, P.; Zwally, H.J.; Wilheit, T.T.; Chang, T.C.; Hall, D.; Gray, L.; Meeks, D.C.; Bryan, M.L.; Barath, F.T.; Elachi, C.; Leberl, F.; Farr, Tom

1978-01-01

During the AIDJEX Main Experiment, April 1975 through May 1976, a comprehensive microwave sensing program was performed on the sea ice of the Beaufort Sea. Surface and aircraft measurements were obtained during all seasons using a wide variety of active and passive microwave sensors. The surface program obtained passive microwave measurements of various ice types using four antennas mounted on a tracked vehicle. In three test regions, each with an area of approximately 1.5 ?? 104 m2, detailed ice crystallographic, dielectric properties, and brightness temperatures of first-year, multiyear, and first-year/multiyear mixtures were measured. A NASA aircraft obtained passive microwave measurements of the entire area of the AIDJEX manned station array (triangle) during each of 18 flights. This verified the earlier reported ability to distinguish first-year and multiyear ice types and concentration and gave new information on ways to observe ice mixtures and thin ice types. The active microwave measurements from aircraft included those from an X- and L-band radar and from a scatterometer. The former is used to study a wide variety of ice features and to estimate deformations, while both are equally usable to observe ice types. With the present data, only the scatterometer can be used to distinguish positively multiyear from first-year and various types of thin ice. This is best done using coupled active and passive microwave sensing. ?? 1978 D. Reidel Publishing Company.

Gaussian statistics of the cosmic microwave background: Correlation of temperature extrema in the COBE DMR two-year sky maps

NASA Technical Reports Server (NTRS)

Kogut, A.; Banday, A. J.; Bennett, C. L.; Hinshaw, G.; Lubin, P. M.; Smoot, G. F.

1995-01-01

We use the two-point correlation function of the extrema points (peaks and valleys) in the Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) 2 year sky maps as a test for non-Gaussian temperature distribution in the cosmic microwave background anisotropy. A maximum-likelihood analysis compares the DMR data to n = 1 toy models whose random-phase spherical harmonic components a(sub lm) are drawn from either Gaussian, chi-square, or log-normal parent populations. The likelihood of the 53 GHz (A+B)/2 data is greatest for the exact Gaussian model. There is less than 10% chance that the non-Gaussian models tested describe the DMR data, limited primarily by type II errors in the statistical inference. The extrema correlation function is a stronger test for this class of non-Gaussian models than topological statistics such as the genus.

High brightness microwave lamp

DOEpatents

Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

2003-09-09

An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

Microwave detector

DOEpatents

Meldner, Heiner W.; Cusson, Ronald Y.; Johnson, Ray M.

1986-01-01

A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

Fast microwave assisted pyrolysis of biomass using microwave absorbent.

PubMed

Borges, Fernanda Cabral; Du, Zhenyi; Xie, Qinglong; Trierweiler, Jorge Otávio; Cheng, Yanling; Wan, Yiqin; Liu, Yuhuan; Zhu, Rongbi; Lin, Xiangyang; Chen, Paul; Ruan, Roger

2014-03-01

A novel concept of fast microwave assisted pyrolysis (fMAP) in the presence of microwave absorbents was presented and examined. Wood sawdust and corn stover were pyrolyzed by means of microwave heating and silicon carbide (SiC) as microwave absorbent. The bio-oil was characterized, and the effects of temperature, feedstock loading, particle sizes, and vacuum degree were analyzed. For wood sawdust, a temperature of 480°C, 50 grit SiC, with 2g/min of biomass feeding, were the optimal conditions, with a maximum bio-oil yield of 65 wt.%. For corn stover, temperatures ranging from 490°C to 560°C, biomass particle sizes from 0.9mm to 1.9mm, and vacuum degree lower than 100mmHg obtained a maximum bio-oil yield of 64 wt.%. This study shows that the use of microwave absorbents for fMAP is feasible and a promising technology to improve the practical values and commercial application outlook of microwave based pyrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

WMAP - A Portrait of the Early Universe

NASA Technical Reports Server (NTRS)

Wollack, Edward J.

2008-01-01

A host of astrophysical observations suggest that early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the 'Big Bang' and the signature of the evolution of its contents. By exploiting these clues, constraints on the age, mass density, and geometry of the early Universe can be derived. A brief history of the evolution of the microwave radiometer systems and map making approaches used in advancing these aspects our understanding of cosmological will be reviewed. In addition, an overview of the results from NASA's Wilkinson Microwave Anisotropy (WMAP) will be presented.

Microwave remote sensing of sea ice in the AIDJEX Main Experiment. [Arctic Ice Dynamics Joint Experiment

NASA Technical Reports Server (NTRS)

Campbell, W. J.; Wayenberg, J.; Ramseyer, J. B.; Ramseier, R. O.; Vant, M. R.; Weaver, R.; Redmond, A.; Arsenault, L.; Gloersen, P.; Zwally, H. J.

1978-01-01

A microwave remote sensing program of sea ice in the Beaufort Sea was conducted during the Arctic Ice Dynamics Joint Experiment (AIDJEX). Several types of both passive and active sensors were used to perform surface and aircraft measurements during all seasons of the year. In situ observations were made of physical properties (salinity, temperature, density, surface roughness), dielectric properties, and passive microwave measurements were made of first-year, multiyear, and first-year/multiyear mixtures. Airborne passive microwave measurements were performed with the electronically scanning microwave radiometer while airborne active microwave measurements were performed by synthetic aperture radar, X- and L-band radar, and a scatterometer.

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

2009-01-01

This disk contains 2 videos that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The 1st video shows the results of the COMSOL

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

2009-01-01

This disk contains a video that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The video shows the partial results of the COMSOL

Continuity of Climate Data Records derived from Microwave Observations

NASA Astrophysics Data System (ADS)

Mears, C. A.; Wentz, F. J.; Brewer, M.; Meissner, T.; Ricciardulli, L.

2017-12-01

Remote Sensing Systems (www.remss.com) has been producing and distributing microwave climate data products from microwave imagers (SSMI, TMI, AMSR, WindSat, GMI, Aquarius, SMAP) over the global oceans since the launch of the first SSMI in 1987. Interest in these data products has been significant as researchers around the world have downloaded the approximate equivalent of 1 million satellite years of processed data. Users, including NASA, NOAA, US National Laboratories, US Navy, UK Met, ECMWF, JAXA, JMA, CMC, the Australian Bureau of Meteorology, as well as many hundreds of other agencies and universities routinely access these microwave data products. The quality of these data records has increased as more observations have become available and inter-calibration techniques have improved. The impending end of missions for WindSat, AMSR-2, and the remaining SSMIs will have significant impact on the quality and continuity of long term microwave climate data records. In addition to the problem of reduced numbers of observations, there is a real danger of losing overlapping observations. Simultaneous operation of satellites, especially when the observations are at similar local crossing times, provides a significant benefit in the effort to inter-calibrate satellites to yield accurate and stable long-term records. The end of WindSat and AMSR-2 will leave us without microwave SSTs in cold water, as there will be no microwave imagers with C-band channels. Microwave SSTs have a crucial advantage over IR SSTs, which is not able to measure SST in clouds or if aerosols are present. The gap in ocean wind vectors will be somewhat mitigated as the European ASCAT C-band scatterometer mission on MetOp is continuing. Nonetheless, the anticipated cease of several microwave satellite radiometers retrieving ocean winds in the coming years will lead to a significant gap in temporal coverage. Atmospheric water vapor, cloud liquid water, and rain rate are all important climate

INCREASING EVIDENCE FOR HEMISPHERICAL POWER ASYMMETRY IN THE FIVE-YEAR WMAP DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoftuft, J.; Eriksen, H. K.; Hansen, F. K.

Motivated by the recent results of Hansen et al. concerning a noticeable hemispherical power asymmetry in the Wilkinson Microwave Anisotropy Probe (WMAP) data on small angular scales, we revisit the dipole-modulated signal model introduced by Gordon et al.. This model assumes that the true cosmic microwave background signal consists of a Gaussian isotropic random field modulated by a dipole, and is characterized by an overall modulation amplitude, A, and a preferred direction, p-hat. Previous analyses of this model have been restricted to very low resolution (i.e., 3.{sup 0}6 pixels, a smoothing scale of 9 deg. FWHM, and l {approx}< 40)more » due to computational cost. In this paper, we double the angular resolution (i.e., 1.{sup 0}8 pixels and 4.{sup 0}5 FWHM smoothing scale), and compute the full corresponding posterior distribution for the five-year WMAP data. The results from our analysis are the following: the best-fit modulation amplitude for l {<=} 64 and the ILC data with the WMAP KQ85 sky cut is A = 0.072 {+-} 0.022, nonzero at 3.3{sigma}, and the preferred direction points toward Galactic coordinates (l, b) = (224 deg., - 22 deg.) {+-} 24 deg. The corresponding results for l {approx}< 40 from earlier analyses were A = 0.11 {+-} 0.04 and (l, b) = (225 deg. - 27 deg.). The statistical significance of a nonzero amplitude thus increases from 2.8{sigma} to 3.3{sigma} when increasing l{sub max} from 40 to 64, and all results are consistent to within 1{sigma}. Similarly, the Bayesian log-evidence difference with respect to the isotropic model increases from {delta}ln E = 1.8 to {delta}ln E = 2.6, ranking as 'strong evidence' on the Jeffreys' scale. The raw best-fit log-likelihood difference increases from {delta}ln L = 6.1 to {delta}ln L = 7.3. Similar, and often slightly stronger, results are found for other data combinations. Thus, we find that the evidence for a dipole power distribution in the WMAP data increases with l in the five-year WMAP data set, in

Variable frequency microwave heating apparatus

DOEpatents

Bible, Don W.; Lauf, Robert J.; Johnson, Arvid C.; Thigpen, Larry T.

1999-01-01

A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Constraints on the cosmological parameters from BICEP2, Planck, and WMAP

NASA Astrophysics Data System (ADS)

Cheng, Cheng; Huang, Qing-Guo

2014-11-01

In this paper we constrain the cosmological parameters, in particular the tilt of tensor power spectrum, by adopting Background Imaging of Cosmic Extragalactic Polarization (B2), Planck released in 2013 and Wilkinson Microwaves Anisotropy Probe 9-year Polarization data. We find that a blue tilted tensor power spectrum is preferred at more than confidence level if the data from B2 are assumed to be totally interpreted as the relic gravitational waves, but a scale-invariant tensor power spectrum is consistent with the data once the polarized dust is taken into account. The recent Planck 353 GHz HFI dust polarization data imply that the B2 data are perfectly consistent with there being no gravitational wave signal.

Land Surface Microwave Emissivity Dynamics: Observations, Analysis and Modeling

NASA Technical Reports Server (NTRS)

Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Kumar, Sujay; Ringerud, Sarah

2014-01-01

Land surface microwave emissivity affects remote sensing of both the atmosphere and the land surface. The dynamical behavior of microwave emissivity over a very diverse sample of land surface types is studied. With seven years of satellite measurements from AMSR-E, we identified various dynamical regimes of the land surface emission. In addition, we used two radiative transfer models (RTMs), the Community Radiative Transfer Model (CRTM) and the Community Microwave Emission Modeling Platform (CMEM), to simulate land surface emissivity dynamics. With both CRTM and CMEM coupled to NASA's Land Information System, global-scale land surface microwave emissivities were simulated for five years, and evaluated against AMSR-E observations. It is found that both models have successes and failures over various types of land surfaces. Among them, the desert shows the most consistent underestimates (by approx. 70-80%), due to limitations of the physical models used, and requires a revision in both systems. Other snow-free surface types exhibit various degrees of success and it is expected that parameter tuning can improve their performances.

Microwave components for cellular portable radiotelephone

NASA Astrophysics Data System (ADS)

Muraguchi, Masahiro; Aikawa, Masayoshi

1995-09-01

Mobile and personal communication systems are expected to represent a huge market for microwave components in the coming years. A number of components in silicon bipolar, silicon Bi-CMOS, GaAs MESFET, HBT and HEMT are now becoming available for system application. There are tradeoffs among the competing technologies with regard to performance, cost, reliability and time-to-market. This paper describes process selection and requirements of cost and r.f. performances to microwave semiconductor components for digital cellular and cordless telephones. Furthermore, new circuit techniques which were developed by NTT are presented.

The application of microwave photonic detection in quantum communication

NASA Astrophysics Data System (ADS)

Diao, Wenting; Zhuang, Yongyong; Song, Xuerui; Wang, Liujun; Duan, Chongdi

2018-03-01

Quantum communication has attracted much attention in recent years, provides an ultimate level of security, and uniquely it is one of the most likely practical quantum technologies at present. In order to realize global coverage of quantum communication networks, not only need the help of satellite to realize wide area quantum communication, need implementation of optical fiber system to realize city to city quantum communication, but also, it is necessary to implement end-to-end quantum communications intercity and wireless quantum communications that can be received by handheld devices. Because of the limitation of application of light in buildings, it needs quantum communication with microwave band to achieve quantum reception of wireless handheld devices. The single microwave photon energy is very low, it is difficult to directly detect, which become a difficulty in microwave quantum detection. This paper summarizes the mode of single microwave photon detection methods and the possibility of application in microwave quantum communication, and promotes the development of quantum communication in microwave band and quantum radar.

EDITORIAL: Microwave Moisture Measurements

NASA Astrophysics Data System (ADS)

Kaatze, Udo; Kupfer, Klaus; Hübner, Christof

2007-04-01

Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precise measurements of the water content are thus extremely useful in pure sciences, particularly in biochemistry and biophysics. They are likewise important in many agricultural, technical and industrial fields. Applications are broad and diverse, and include the quality assessment of foodstuffs, the determination of water content in paper, cardboard and textile production, the monitoring of moisture in sands, gravels, soils and constructions, as well as the measurement of water admixtures to coal and crude oil in reservoirs and in pipelines. Microwave moisture measurements and evaluations require insights in various disciplines, such as materials science, dielectrics, the physical chemistry of water, electrodynamics and microwave techniques. The cooperation of experts from the different fields of science is thus necessary for the efficient development of this complex discipline. In order to advance cooperation the Workshop on Electromagnetic Wave Interaction with Water and Moist Substances was held in 1993 in Atlanta. It initiated a series of international conferences, of which the last one was held in 2005 in Weimar. The meeting brought together 130 scientists and engineers from all over the world. This special issue presents a collection of some selected papers that were given at the event. The papers cover most topics of the conference, featuring dielectric properties of aqueous materials, electromagnetic wave interactions, measurement methods and sensors, and various applications. The special issue is dedicated to Dr Andrzej W Kraszewski, who died in July 2006 after a distinguished career of 48 years in the research of

Microwave quantum illumination.

PubMed

Barzanjeh, Shabir; Guha, Saikat; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

2015-02-27

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here, we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy.

Effects of Exposure to Microwaves: Problems and Perspectives*

PubMed Central

Michaelson, Sol M.

1974-01-01

During the last 25 years, there has been a remarkable development and increase in the number of processes and devices that utilize or emit microwaves. Such devices are used in all sectors of our society for military, industrial, telecommunications, and consumer applications. Although there is information on biologic effects and potential hazard to man from exposure to microwaves, considerable confusion and misinformation has permeated not only the public press but also some scientific and technical publications. The purpose of this review is to place the available information on biologic effects of microwaves in proper perspective and to suggest approaches to future studies. PMID:4620329

Microwave ion source

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Thomae, Rainer W.

2005-07-26

A compact microwave ion source has a permanent magnet dipole field, a microwave launcher, and an extractor parallel to the source axis. The dipole field is in the form of a ring. The microwaves are launched from the middle of the dipole ring using a coaxial waveguide. Electrons are heated using ECR in the magnetic field. The ions are extracted from the side of the source from the middle of the dipole perpendicular to the source axis. The plasma density can be increased by boosting the microwave ion source by the addition of an RF antenna. Higher charge states can be achieved by increasing the microwave frequency. A xenon source with a magnetic pinch can be used to produce intense EUV radiation.

Microwave emission measurements of sea surface roughness, soil moisture, and sea ice structure

NASA Technical Reports Server (NTRS)

Gloersen, P.; Wilheit, T. T.; Schmugge, T. J.

1972-01-01

In order to demonstrate the feasibility of the microwave radiometers to be carried aboard the Nimbus 5 and 6 satellites and proposed for one of the earth observatory satellites, remote measurements of microwave radiation at wavelengths ranging from 0.8 to 21 cm have been made of a variety of the earth's surfaces from the NASA CV-990 A/C. Brightness temperatures of sea water surfaces of varying roughness, of terrain with varying soil moisture, and of sea ice of varying structure were observed. In each case, around truth information was available for correlation with the microwave brightness temperature. The utility of passive microwave radiometry in determining ocean surface wind speeds, at least for values higher than 7 meters/second has been demonstrated. In addition, it was shown that radiometric signatures can be used to determine soil moisture in unvegetated terrain to within five percentage points by weight. Finally, it was demonstrated that first year thick, multi-year, and first year thin sea ice can be distinguished by observing their differing microwave emissivities at various wavelengths.

Microwave-superheated Vics Vapo Rub: an ocular public health danger.

PubMed

Fung, Anne E; Oxford, Karen W

2004-02-01

To report a case of a microwave-oven superheated petroleum-based liquid causing severe chemical and thermal ocular burns treated successfully with amniotic membrane transplantation. Observational case report. Retrospective review of clinical case. A 77-year-old woman sustained a severe combined chemical and thermal burn from microwave-heated Vicks Vapo-Rub requiring amniotic membrane transplant, with subsequent development of phacomorphic glaucoma, requiring cataract extraction, and bullous keratopathy, requiring penetrating keratoplasty. As microwave oven use becomes more commonplace, the risk of superheating liquids becomes an increasingly significant ocular danger. Continued efforts to educate the public about safe microwave use is necessary. Additionally, amniotic membrane transplantation was found to be effective in managing a combined chemical and thermal ocular burn.

Effects of Microwave Radiation on Oil Recovery

NASA Astrophysics Data System (ADS)

Esmaeili, Abdollah

2011-12-01

A variety of oil recovery methods have been developed and applied to mature and depleted reservoirs in order to improve the efficiency. Microwave radiation oil recovery method is a relatively new method and has been of great interest in the recent years. Crude oil is typically co-mingled with suspended solids and water. To increase oil recovery, it is necessary to remove these components. The separation of oil from water and solids using gravitational settling methods is typically incomplete. Oil-in-water and oil-water-solid emulsions can be demulsified and separated into their individual layers by microwave radiation. The data also show that microwave separation is faster than gravity separation and can be faster than conventional heating at many conditions. After separation of emulsion into water and oil layers, water can be discharged and oil is collected. High-frequency microwave recycling process can recover oil and gases from oil shale, residual oil, drill cuttings, tar sands oil, contaminated dredge/sediments, tires and plastics with significantly greater yields and lower costs than are available utilizing existing known technologies. This process is environmentally friendly, fuel-generating recycler to reduce waste, cut emissions, and save energy. This paper presents a critical review of Microwave radiation method for oil recovery.

Variable frequency microwave furnace system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bible, D.W.; Lauf, R.J.

1994-06-14

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal inputmore » to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.« less

Variable frequency microwave furnace system

DOEpatents

Bible, D.W.; Lauf, R.J.

1994-06-14

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.

Passive microwave algorithm development and evaluation

NASA Technical Reports Server (NTRS)

Petty, Grant W.

1995-01-01

The scientific objectives of this grant are: (1) thoroughly evaluate, both theoretically and empirically, all available Special Sensor Microwave Imager (SSM/I) retrieval algorithms for column water vapor, column liquid water, and surface wind speed; (2) where both appropriate and feasible, develop, validate, and document satellite passive microwave retrieval algorithms that offer significantly improved performance compared with currently available algorithms; and (3) refine and validate a novel physical inversion scheme for retrieving rain rate over the ocean. This report summarizes work accomplished or in progress during the first year of a three year grant. The emphasis during the first year has been on the validation and refinement of the rain rate algorithm published by Petty and on the analysis of independent data sets that can be used to help evaluate the performance of rain rate algorithms over remote areas of the ocean. Two articles in the area of global oceanic precipitation are attached.

Microwave hemorrhagic stroke detector

DOEpatents

Haddad, Waleed S.; Trebes, James E.

2002-01-01

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Microwave hemorrhagic stroke detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haddad, Waleed S; Trebes, James E

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device ismore » based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.« less

Not child's play: National estimates of microwave-related burn injuries among young children.

PubMed

Lowell, Gina; Quinlan, Kyran

2016-10-01

Previous studies have shown that children as young as 18 months can open a microwave and remove its contents causing sometimes severe scalds. Although this mechanism may be uniquely preventable by an engineering fix, no national estimate of this type of child burn injury has been reported. We analyzed the Consumer Product Safety Commission's National Electronic Injury Surveillance System data on emergency department-treated microwave-related burn injuries from January 2002 through December 2012 in children aged 12 months to 4 years. Based on the narrative description of how the injury occurred, we defined a case as a burn with a mechanism of either definitely or probably involving a child himself or herself opening a microwave oven and accessing the heated contents. National estimates of cases and their characteristics were calculated. During the 11 years studied, an estimated 10,902 (95% confidence interval, 8,231-13,573) microwave-related burns occurred in children aged 12 months to 4 years. Of these, 7,274 (66.7%) (95% confidence interval, 5,135-9,413) were cases of children burned after accessing the contents of the microwave themselves. A total of 1,124 (15.5%) cases required hospitalization or transfer from the treating emergency department. Narratives for children as young as 12 months described the child himself or herself being able to access microwave contents. The most commonly burned body parts were the upper trunk (3,056 cases) and the face (1,039 cases). The most common scalding substances were water (2,863 cases), noodles (1,011 cases), and soup (931 cases). The majority of microwave-related burns in young children occur as a result of the child himself or herself accessing the microwave and removing the contents. More than 600 young children are treated in US emergency departments annually for such burns. Children as young as 12 months sustained burns caused by this mechanism of injury. These burns could be prevented with a redesign of microwaves to

Review of Microwave Photonics Technique to Generate the Microwave Signal by Using Photonics Technology

NASA Astrophysics Data System (ADS)

Raghuwanshi, Sanjeev Kumar; Srivastav, Akash

2017-12-01

Microwave photonics system provides high bandwidth capabilities of fiber optic systems and also contains the ability to provide interconnect transmission properties, which are virtually independent of length. The low-loss wide bandwidth capability of optoelectronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. So, we can considered microwave photonics as the field that studies the interaction between microwave and optical waves for applications such as communications, radars, sensors and instrumentations. In this paper we have thoroughly reviewed the microwave generation techniques by using photonics technology.

Cosmic temperature fluctuations from two years of COBE differential microwave radiometers observations

NASA Technical Reports Server (NTRS)

Bennett, C. L.; Kogut, A.; Hinshaw, G.; Banday, A. J.; Wright, E. L.; Gorski, K. M.; Wilkinson, D. T.; Weiss, R.; Smoot, G. F.; Meyer, S. S.

1994-01-01

The first two years of Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) observations of the cosmic microwave background (CMB) anisotropy are analyzed and compared with our previously published first year results. The results are consistent, but the addition of the second year of data increases the precision and accuracy detected CMB temperature fluctuations. The 2 yr 53 GHz data are characterized by rms temperature fluctuations of (delta-T)(sub rms) (7 deg) = 44 +/- 7 micro-K and (delta-T)(sub rms) (10 deg) = 30.5 +/- 2.7 micro-K at 7 deg and 10 deg angular resolution, respectively. The 53 x 90 GHz cross-correlation amplitude at zero lag is C(0)(sup 1/2) = 36 +/- 5 micro-K (68% CL) for the unsmoothed (7 deg resolution) DMR data. We perform a likelihood analysis of the cross-correlation function, with Monte Carlo simulations to infer biases of the method, for a power-law model of initial density fluctuations, P(k) proportional to R(exp n). The Monte Carlo simulations indicate that derived estimates of n are biased by +0.11 +/- 0.01, while the subset of simulations with a low quadrupole (as observed) indicate a bias of +0.31+/- 0.04. Derived values for 68% confidence intervals are given corrected (and not corrected) for our estimated biases. Including the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(sub rms-PS) = 14.3(sup + 5.2 sub -3.3) micro-K (12.8(sup + 5.2 sub -3.3) micro-K0 with a spectral index n = 1.42(sup + 0.49 sub -0.55)(n = 1.53(sup + 0.49 sub -0.55). With n fixed to 1.0 the most likely amplitude is 18.2 +/- 11.5 micro-K (17.4 +/- 1.5 micro-K). The marginal likelihood of n is 1.42 +/- 0.37 (1.53 +/- 0.37). Excluding the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(sub rms-PS) = 17.4(sup + 7.5 sub -5.2) micro-K (15.8(sup + 7.5 sub -5.2) micro-K) with a spectral index n = 1.11(sup + 0.60 sub -0.55) (n = 1.22(sup + 0.60 sub -0.55). With n fixed to 1.0 the most likely

Insights into a microwave susceptible agent for minimally invasive microwave tumor thermal therapy.

PubMed

Shi, Haitang; Liu, Tianlong; Fu, Changhui; Li, Linlin; Tan, Longfei; Wang, Jingzhuo; Ren, Xiangling; Ren, Jun; Wang, Jianxin; Meng, Xianwei

2015-03-01

This work develops a kind of sodium alginate (SA) microcapsules as microwave susceptible agents for in vivo tumor microwave thermal therapy for the first time. Due to the excellent microwave susceptible properties and low bio-toxicity, excellent therapy efficiency can be achieved with the tumor inhibiting ratio of 97.85% after one-time microwave thermal therapy with ultralow power (1.8 W, 450 MHz). Meanwhile, the mechanism of high microwave heating efficiency was confirmed via computer-simulated model in theory, demonstrating that the spatial confinement efficiency of microcapsule walls endows the inside ions with high microwave susceptible properties. This strategy offers tremendous potential applications in clinical tumor treatment with the benefits of safety, reliability, effectiveness and minimally invasiveness. Copyright © 2014 Elsevier Ltd. All rights reserved.

The electromagnetic wave energy effect(s) in microwave-assisted organic syntheses (MAOS).

PubMed

Horikoshi, Satoshi; Watanabe, Tomoki; Narita, Atsushi; Suzuki, Yumiko; Serpone, Nick

2018-03-26

Organic reactions driven by microwaves have been subjected for several years to some enigmatic phenomenon referred to as the microwave effect, an effect often mentioned in microwave chemistry but seldom understood. We identify this microwave effect as an electromagnetic wave effect that influences many chemical reactions. In this article, we demonstrate its existence using three different types of microwave generators with dissimilar oscillation characteristics. We show that this effect is operative in photocatalyzed TiO 2 reactions; it negatively influences electro-conductive catalyzed reactions, and yet has but a negligible effect on organic syntheses. The relationship between this electromagnetic wave effect and chemical reactions is elucidated from such energetic considerations as the photon energy and the reactions' activation energies.

Beaufort Sea ice zones as delineated by microwave imagery

NASA Technical Reports Server (NTRS)

Campbell, W. J.; Gloersen, P.; Webster, W. J.; Wilheit, T. T.; Ramseier, R. O.

1976-01-01

Microwave and infrared data were obtained from a research aircraft over the Beaufort Sea ice from the shoreline of Harrison Bay northward to a latitude of almost 81 deg N. The data acquired were compared with microwave data obtained on the surface at an approximate position of 75 deg N, 150 deg W. Over this north-south transect of the polar ice canopy it was discovered that the sea ice could be divided into five distinct zones. The shorefast sea ice was found to consist uniformly of first-year sea ice. The second zone was found to be a mixture of first-year sea ice, medium size multiyear floes, and many recently refrozen leads, polynyas, and open water; considerable shearing activity was evident in this zone. The third zone was a mixture of first-year and multiyear sea ice which had a uniform microwave signature. The fourth zone was found to be a mixture of first-year sea ice and medium-to-large size multiyear floes which was similar in composition to the second zone. The fifth zone was almost exclusively multiyear ice extending to the North Pole.

Variable frequency microwave furnace system

DOEpatents

Bible, Don W.; Lauf, Robert J.

1994-01-01

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Microwave thawing apparatus and method

DOEpatents

Fathi, Zakaryae; Lauf, Robert J.; McMillan, April D.

2004-06-01

An apparatus for thawing a frozen material includes: a microwave energy source; a microwave applicator which defines a cavity for applying microwave energy from the microwave source to a material to be thawed; and a shielded region which is shielded from the microwave source, the shielded region in fluid communication with the cavity so that thawed material may flow from the cavity into the shielded region.

Microwave-driven ultraviolet light sources

DOEpatents

Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

2002-01-29

A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

Innovative microwave design leads to smart, small EW systems

NASA Astrophysics Data System (ADS)

Niehenke, Edward C.

1988-02-01

An account is given of the state-of-the-art in microwave component and system design for EW systems, whose size and weight has been progressively reduced in recent years as a result of continuing design innovation in microwave circuitry. Typically, AI-function computers are employed to control microwave functions in a way that allows rapid RAM or ROM software modification to meet new performance requirements, thereby obviating hardware modifications. Attention is given to high-isolation GaAs MMIC filters, switches and amplifiers, frequency converters, instantaneous frequency measurement systems, frequency translators, digital RF memories, and high effective radiated power solid-state active antenna arrays.

Non-military microwave applications

NASA Astrophysics Data System (ADS)

Bierman, Howard

1990-04-01

The nonmilitary applications of microwave technology in medicine, communications, and agriculture are discussed. Particular attention is given to a microwave multichannel multipoint video distribution system (a broadcasting system with up to 20 programs drawn from satellites, video tape libraries, and locally generated material); microwaves used in DBS distribution; satellite receivers for data communications; microwave thermography used for early cancer detection, brain temperature measurements, and appendicitis diagnosis; an experimental Doppler radar assembly for guiding robots walking on a factory floor; and an agricultural application where microwaves are used to break down slugs in soil and thus improve potato and grain crops. Schematic diagrams are included.

Microwave Moisture Sensing of Seedcotton: Part 1: Seedcotton Microwave Material Properties.

PubMed

Pelletier, Mathew G; Wanjura, John D; Holt, Greg A

2016-11-02

Moisture content at harvest is a key parameter that impacts quality and how well the cotton crop can be stored without degrading before processing. It is also a key parameter of interest for harvest time field trials as it can directly influence the quality of the harvested crop as well as skew the results of in-field yield and quality assessments. Microwave sensing of moisture has several unique advantages over lower frequency sensing approaches. The first is that microwaves are insensitive to variations in conductivity, due to presence of salts or minerals. The second advantage is that microwaves can peer deep inside large bulk packaging to assess the internal moisture content without performing a destructive tear down of the package. To help facilitate the development of a microwave moisture sensor for seedcotton; research was performed to determine the basic microwave properties of seedcotton. The research was performed on 110 kg micro-modules, which are of direct interest to research teams for use in ongoing field-based research projects. It should also prove useful for the enhancement of existing and future yield monitor designs. Experimental data was gathered on the basic relations between microwave material properties and seedcotton over the range from 1.0 GHz to 2.5 GHz and is reported on herein. This research is part one of a two-part series that reports on the fundamental microwave properties of seedcotton as moisture and density vary naturally during the course of typical harvesting operations; part two will utilize this data to formulate a prediction algorithm to form the basis for a prototype microwave moisture sensor.

Microwave Moisture Sensing of Seedcotton: Part 1: Seedcotton Microwave Material Properties

PubMed Central

Pelletier, Mathew G.; Wanjura, John D.; Holt, Greg A.

2016-01-01

Moisture content at harvest is a key parameter that impacts quality and how well the cotton crop can be stored without degrading before processing. It is also a key parameter of interest for harvest time field trials as it can directly influence the quality of the harvested crop as well as skew the results of in-field yield and quality assessments. Microwave sensing of moisture has several unique advantages over lower frequency sensing approaches. The first is that microwaves are insensitive to variations in conductivity, due to presence of salts or minerals. The second advantage is that microwaves can peer deep inside large bulk packaging to assess the internal moisture content without performing a destructive tear down of the package. To help facilitate the development of a microwave moisture sensor for seedcotton; research was performed to determine the basic microwave properties of seedcotton. The research was performed on 110 kg micro-modules, which are of direct interest to research teams for use in ongoing field-based research projects. It should also prove useful for the enhancement of existing and future yield monitor designs. Experimental data was gathered on the basic relations between microwave material properties and seedcotton over the range from 1.0 GHz to 2.5 GHz and is reported on herein. This research is part one of a two-part series that reports on the fundamental microwave properties of seedcotton as moisture and density vary naturally during the course of typical harvesting operations; part two will utilize this data to formulate a prediction algorithm to form the basis for a prototype microwave moisture sensor. PMID:27827857

An inter-sensor comparison of the microwave signatures of Arctic sea ice

NASA Technical Reports Server (NTRS)

Onstott, R. G.

1986-01-01

Active and passive microwave and physical properties of Arctic sea ice in the marginal ice zone were measured during the summer. Results of an intercomparison of data acquired by an aircraft synthetic aperture radar, a passive microwave imager and a helicopter-mounted scatterometer indicate that early-to-mid summer sea ice microwave signatures are dominated by snowpack characteristics. Measurements show that the greatest contrast between thin first-year and multiyear sea ice occurs when operating actively between 5 and 10 GHz. Significant information about the state of melt of snow and ice is contained in the active and passive microwave signatures.

Microwave generator

DOEpatents

Kwan, T.J.T.; Snell, C.M.

1987-03-31

A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

Microwave holographic metrology for antenna diagnosis

NASA Astrophysics Data System (ADS)

Rahmat-Samii, Y.

1990-11-01

Advances in antenna diagnostic methodologies have been very significant in recent years. In particular, microwave holographic diagnostic techniques have been applied very successfully in improving the performance of reflector and array antennas. These techniques use the knowledge of the measured amplitude and phase of the antenna radiated fields and then take advantage of the existing Fourier transform relationships between the radiated fields and the effective aperture or current distribution to eventually determine the reflector surface or array excitation coefficients anomalies. In this paper an overview of the recent developments in applying microwave holography is presented. The theoretical, numerical and measurement aspects of this technique is detailed by providing representative results.

Unraveling the mysteries of microwave chemistry using silicon carbide reactor technology.

PubMed

Kappe, C Oliver

2013-07-16

In the past few years, the use of microwave energy to heat chemical reactions has become an increasingly popular theme in the scientific community. This nonclassical heating technique has slowly progressed from a laboratory curiosity to an established method commonly used both in academia and in industry. Because of its efficiency, microwave heating dramatically reduces reaction times (from days and hours to minutes and seconds) and improves product purities or material properties among other advantages. Since the early days of microwave chemistry, researchers have observed rate-accelerations and, in some cases, altered product distributions as compared with reactions carried out using classical oil-bath heating. As a result, researchers have speculated that so-called specific or nonthermal microwave effects could be responsible for these differences. Much of the debate has centered on the question of whether the electromagnetic field can exert a direct influence on a chemical transformation outside of the simple macroscopic change in bulk reaction temperature. In 2009, our group developed a relatively simple "trick" that allows us to rapidly evaluate whether an observed effect seen in a microwave-assisted reaction results from a purely thermal phenomenon, or involves specific or nonthermal microwave effects. We use a microwave reaction vessel made from silicon carbide (SiC) ceramic. Because of its high microwave absorptivity, the vessel shields its contents from the electromagnetic field. As a result, we can easily mimic a conventionally heated autoclave experiment inside a microwave reactor under carefully controlled reaction conditions. The switch from an almost microwave transparent glass (Pyrex) to a strongly microwave absorbing SiC reaction vial under otherwise identical reaction conditions (temperature profiles, pressure, stirring speed) then allows us to carefully evaluate the influence of the electromagnetic field on the particular chemical transformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onić, D.; Urošević, D.; Leahy, D., E-mail: donic@matf.bg.ac.rs

Recent observations of the microwave sky, by space telescopes such as the Wilkinson Microwave Anisotropy Probe and Planck , have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of currently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility is emphasized that the slight bump in the integrated continuum of this remnant around 20–70 GHz is genuine and that it can be explained by the contribution of an additional emission mechanism suchmore » as spinning dust. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while at the same time preserving the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mody, Krishnan; Hajian, Amir, E-mail: kmody@princeton.edu, E-mail: ahajian@cita.utoronto.ca

We present our measurement of the 'bulk flow' using the kinetic Sunyaev-Zel'dovich (kSZ) effect in the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year data. As the tracer of peculiar velocities, we use Planck Early Sunyaev-Zel'dovich Detected Cluster Catalog and a compilation of X-ray-detected galaxy cluster catalogs based on ROSAT All-Sky Survey. We build a full-sky kSZ template and fit it to the WMAP data in W band. Using a Wiener filter we maximize the signal-to-noise ratio of the kSZ cluster signal in the data. We find no significant detection of the bulk flow, and our results are consistent with the {Lambda}CDMmore » prediction.« less

Digital communications: Microwave applications

NASA Astrophysics Data System (ADS)

Feher, K.

Transmission concepts and techniques of digital systems are presented; and practical state-of-the-art implementation of digital communications systems by line-of-sight microwaves is described. Particular consideration is given to statistical methods in digital transmission systems analysis, digital modulation methods, microwave amplifiers, system gain, m-ary and QAM microwave systems, correlative techniques and applications to digital radio systems, hybrid systems, digital microwave systems design, diversity and protection switching techniques, measurement techniques, and research and development trends and unsolved problems.

Microwave processing heats up

USDA-ARS?s Scientific Manuscript database

Microwaves are a common appliance in many households. In the United States microwave heating is the third most popular domestic heating method food foods. Microwave heating is also a commercial food processing technology that has been applied for cooking, drying, and tempering foods. It's use in ...

Polynomial interpretation of multipole vectors

NASA Astrophysics Data System (ADS)

Katz, Gabriel; Weeks, Jeff

2004-09-01

Copi, Huterer, Starkman, and Schwarz introduced multipole vectors in a tensor context and used them to demonstrate that the first-year Wilkinson microwave anisotropy probe (WMAP) quadrupole and octopole planes align at roughly the 99.9% confidence level. In the present article, the language of polynomials provides a new and independent derivation of the multipole vector concept. Bézout’s theorem supports an elementary proof that the multipole vectors exist and are unique (up to rescaling). The constructive nature of the proof leads to a fast, practical algorithm for computing multipole vectors. We illustrate the algorithm by finding exact solutions for some simple toy examples and numerical solutions for the first-year WMAP quadrupole and octopole. We then apply our algorithm to Monte Carlo skies to independently reconfirm the estimate that the WMAP quadrupole and octopole planes align at the 99.9% level.

Plasma-assisted microwave processing of materials

NASA Technical Reports Server (NTRS)

Barmatz, Martin (Inventor); Jackson, Henry (Inventor); Ylin, Tzu-yuan (Inventor)

1998-01-01

A microwave plasma assisted method and system for heating and joining materials. The invention uses a microwave induced plasma to controllably preheat workpiece materials that are poorly microwave absorbing. The plasma preheats the workpiece to a temperature that improves the materials' ability to absorb microwave energy. The plasma is extinguished and microwave energy is able to volumetrically heat the workpiece. Localized heating of good microwave absorbing materials is done by shielding certain parts of the workpiece and igniting the plasma in the areas not shielded. Microwave induced plasma is also used to induce self-propagating high temperature synthesis (SHS) process for the joining of materials. Preferably, a microwave induced plasma preheats the material and then microwave energy ignites the center of the material, thereby causing a high temperature spherical wave front from the center outward.

PET based nanocomposite films for microwave packaging applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galdi, M. R., E-mail: mrgaldi@unisa.it; Olivieri, R.; Liguori, L.

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress inducedmore » by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of

PET based nanocomposite films for microwave packaging applications

NASA Astrophysics Data System (ADS)

Galdi, M. R.; Olivieri, R.; Liguori, L.; Albanese, D.; Di Matteo, M.; Di Maio, L.

2015-12-01

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress induced by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of PET.

Microwave Lightcraft concept

NASA Technical Reports Server (NTRS)

2004-01-01

Looking like an alien space ship or a flying saucer the Microwave Lightcraft is an unconventional launch vehicle approach for delivering payload to orbit using power transmitted via microwaves. Microwaves re beamed from either a ground station or an orbiting solar power satellite to the lightcraft. The energy received breaks air molecules into a plasma and a magnetohydrodynamic fanjet provides the lifting force. Only a small amount of propellant is required for circulation, attitude control and deorbit.

How Many Cancers Are Linked with HPV Each Year?

MedlinePlus

... 24:1548–1556. 3 Viens LJ, Henley SJ, Watson M, Markowitz LE, Thomas CC, Thompson TD, Razzaghi ... Lynch CF, Hernandez BY, Lyu CW, Steinau M, Watson M, Wilkinson EJ, Hopenhayn C, Copeland G, Cozen ...

Microwave Workshop for Windows.

ERIC Educational Resources Information Center

White, Colin

1998-01-01

"Microwave Workshop for Windows" consists of three programs that act as teaching aid and provide a circuit design utility within the field of microwave engineering. The first program is a computer representation of a graphical design tool; the second is an accurate visual and analytical representation of a microwave test bench; the third…

Cosmic microwave background snapshots: pre-WMAP and post-WMAP.

PubMed

Bond, J Richard; Contaldi, Carlo; Pogosyan, Dmitry

2003-11-15

We highlight the remarkable evolution in the cosmic microwave background (CMB) power spectrum C(l) as a function of multipole l over the past few years, and in the cosmological parameters for minimal inflation models derived from it: from anisotropy results before 2000; in 2000 and 2001 from Boomerang, Maxima and the Degree Angular Scale Interferometer (DASI), extending l to approximately 1000; and in 2002 from the Cosmic Background Imager (CBI), Very Small Array (VSA), ARCHEOPS and Arcminute Cosmology Bolometer Array Receiver (ACBAR), extending l to approximately 3000, with more from Boomerang and DASI as well. Pre-WMAP (pre-Wilkinson Microwave Anisotropy Probe) optimal band powers are in good agreement with each other and with the exquisite one-year WMAP results, unveiled in February 2003, which now dominate the l less, similar 600 bands. These CMB experiments significantly increased the case for accelerated expansion in the early Universe (the inflationary paradigm) and at the current epoch (dark energy dominance) when they were combined with "prior" probabilities on the parameters. The minimal inflation parameter set, [omega(b), omega(cdm), Omega(tot), Omega(Lambda), n(s), tau(C), sigma(8)], is applied in the same way to the evolving data. C(l) database and Monte Carlo Markov Chain (MCMC) methods are shown to give similar values, which are highly stable over time and for different prior choices, with the increasing precision best characterized by decreasing errors on uncorrelated "parameter eigenmodes". Priors applied range from weak ones to stronger constraints from the expansion rate (HST-h), from cosmic acceleration from supernovae (SN1) and from galaxy clustering, gravitational lensing and local cluster abundance (LSS). After marginalizing over the other cosmic and experimental variables for the weak + LSS prior, the pre-WMAP data of January 2003 compared with the post-WMAP data of March 2003 give Omega(tot) = 1.03(-0.04)(+0.05) compared with 1

Lack of large-angle TT correlations persists in WMAP and Planck

NASA Astrophysics Data System (ADS)

Copi, Craig J.; Huterer, Dragan; Schwarz, Dominik J.; Starkman, Glenn D.

2015-08-01

The lack of large-angle correlations in the observed microwave background temperature fluctuations persists in the final-year maps from Wilkinson Microwave Anisotropy Probe (WMAP) and the first cosmological data release from Planck. We find a statistically robust and significant result: p-values for the missing correlations lying below 0.24 per cent (i.e. evidence at more than 3σ) for foreground cleaned maps, in complete agreement with previous analyses based upon earlier WMAP data. A cut-sky analysis of the Planck HFI 100 GHz frequency band, the `cleanest CMB channel' of this instrument, returns a p-value as small as 0.03 per cent, based on the conservative mask defined by WMAP. These findings are in stark contrast to expectations from the inflationary Lambda cold dark matter model and still lack a convincing explanation. If this lack of large-angle correlations is a true feature of our Universe, and not just a statistical fluke, then the cosmological dipole must be considerably smaller than that predicted in the best-fitting model.

Taking the Measure of the Universe: Cosmology from the WMAP Mission

NASA Technical Reports Server (NTRS)

Hinshaw, Gary F.

2006-01-01

The data from the first three years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature anisotropy and new full-sky maps of the polarization. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. These and other aspects of the mission will be discussed. WMAP, part of NASA's Explorers program, was launched on June 30,2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Cornel1 University; University of Chicago; Brown University; University of British Columbia; University of Pennsylvania; and University of California, Los Angeles

An optical model for the microwave properties of sea ice

NASA Technical Reports Server (NTRS)

Gloersen, P.; Larabee, J. K.

1981-01-01

The complex refractive index of sea ice is modeled and used to predict the microwave signatures of various sea ice types. Results are shown to correspond well with the observed values of the complex index inferred from dielectic constant and dielectric loss measurements performed in the field, and with observed microwave signatures of sea ice. The success of this modeling procedure vis a vis modeling of the dielectric properties of sea ice constituents used earlier by several others is explained. Multiple layer radiative transfer calculations are used to predict the microwave properties of first-year sea ice with and without snow, and multiyear sea ice.

Microwave. Instructor's Edition. Louisiana Vocational-Technical Education.

ERIC Educational Resources Information Center

Blanton, William

This publication contains related study assignments and job sheets for a course in microwave technology. The course is organized into 12 units covering the following topics: introduction to microwave, microwave systems, microwave oscillators, microwave modulators, microwave transmission lines, transmission lines, detectors and mixers, microwave…

Microwave Comb Generator

NASA Technical Reports Server (NTRS)

Sigman, E. H.

1989-01-01

Stable reference tones aid testing and calibration of microwave receivers. Signal generator puts out stable tones in frequency range of 2 to 10 GHz at all multiples of reference input frequency, at any frequency up to 1 MHz. Called "comb generator" because spectral plot resembles comb. DC reverse-bias current switched on and off at 1 MHz to generate sharp pulses in step-recovery diode. Microwave components mounted on back of special connector containing built-in attenuator. Used in testing microwave and spread-spectrum wide-band receivers.

SMAP L-Band Microwave Radiometer: Instrument Design and First Year on Orbit

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Focardi, Paolo; Horgan, Kevin; Knuble, Joseph; Ehsan, Negar; Lucey, Jared; Brambora, Clifford; Brown, Paula R.; Hoffman, Pamela J.; French, Richard T.;

Arctic and Antarctic Sea Ice, 1978-1987: Satellite Passive-Microwave Observations and Analysis

NASA Technical Reports Server (NTRS)

Gloersen, Per; Campbell, William J.; Cavalieri, Donald J.; Comiso, Josefino C.; Parkinson, Claire L.; Zwally, H. Jay

1992-01-01

This book contains a description and analysis of the spatial and temporal variations in the Arctic and Antarctic sea ice covers from October 26, 1978 through August 20, 1987. It is based on data collected by the Scanning Multichannel Microwave Radiometer (SMMR) onboard the NASA Nimbus 7 satellite. The 8.8-year period, together with the 4 years of the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) observations presented in two earlier volumes, comprises a sea ice record spanning almost 15 years.

Estimating Soil Moisture from Satellite Microwave Observations

NASA Technical Reports Server (NTRS)

Owe, M.; VandeGriend, A. A.; deJeu, R.; deVries, J.; Seyhan, E.

1998-01-01

Cooperative research in microwave remote sensing between the Hydrological Sciences Branch of the NASA Goddard Space Flight Center and the Earth Sciences Faculty of the Vrije Universiteit Amsterdam began with the Botswana Water and Energy Balance Experiment and has continued through a series of highly successful International Research Programs. The collaboration between these two research institutions has resulted in significant scientific achievements, most notably in the area of satellite-based microwave remote sensing of soil moisture. The Botswana Program was the first joint research initiative between these two institutions, and provided a unique data base which included historical data sets of Scanning Multifrequency Microwave Radiometer (SN4NM) data, climate information, and extensive soil moisture measurements over several large experimental sites in southeast Botswana. These data were the basis for the development of new approaches in physically-based inverse modelling of soil moisture from satellite microwave observations. Among the results from this study were quantitative estimates of vegetation transmission properties at microwave frequencies. A single polarization modelling approach which used horizontally polarized microwave observations combined with monthly composites of Normalized Difference Vegetation Index was developed, and yielded good results. After more precise field experimentation with a ground-based radiometer system, a dual-polarization approach was subsequently developed. This new approach realized significant improvements in soil moisture estimation by satellite. Results from the Botswana study were subsequently applied to a desertification monitoring study for the country of Spain within the framework of the European Community science research programs EFEDA and RESMEDES. A dual frequency approach with only microwave data was used for this application. The Microwave Polarization Difference Index (MPDI) was calculated from 37 GHz data

Gold Nanoparticle Microwave Synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krantz, Kelsie E.; Christian, Jonathan H.; Coopersmith, Kaitlin

At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves formore » gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.« less

The Universe's First Fireworks

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] [figure removed for brevity, see original site] Poster VersionFigure 1Figure 2

This is an image from NASA's Spitzer Space Telescope of stars and galaxies in the Ursa Major constellation. This infrared image covers a region of space so large that light would take up to 100 million years to travel across it. Figure 1 is the same image after stars, galaxies and other sources were masked out. The remaining background light is from a period of time when the universe was less than one billion years old, and most likely originated from the universe's very first groups of objects -- either huge stars or voracious black holes. Darker shades in the image on the left correspond to dimmer parts of the background glow, while yellow and white show the brightest light.

Brief History of the Universe In figure 2, the artist's timeline chronicles the history of the universe, from its explosive beginning to its mature, present-day state.

Our universe began in a tremendous explosion known as the Big Bang about 13.7 billion years ago (left side of strip). Observations by NASA's Cosmic Background Explorer and Wilkinson Anisotropy Microwave Probe revealed microwave light from this very early epoch, about 400,000 years after the Big Bang, providing strong evidence that our universe did blast into existence. Results from the Cosmic Background Explorer were honored with the 2006 Nobel Prize for Physics.

A period of darkness ensued, until about a few hundred million years later, when the first objects flooded the universe with light. This first light is believed to have been captured in data from NASA's Spitzer Space Telescope. The light detected by Spitzer would have originated as visible and ultraviolet light, then stretched, or redshifted, to lower-energy infrared wavelengths during its long voyage to reach us across expanding space. The light detected by the

Uniform batch processing using microwaves

NASA Technical Reports Server (NTRS)

Barmatz, Martin B. (Inventor); Jackson, Henry W. (Inventor)

2000-01-01

A microwave oven and microwave heating method generates microwaves within a cavity in a predetermined mode such that there is a known region of uniform microwave field. Samples placed in the region will then be heated in a relatively identical manner. Where perturbations induced by the samples are significant, samples are arranged in a symmetrical distribution so that the cumulative perturbation at each sample location is the same.

Microwave ablation for unresectable hepatic tumours: clinical results using a novel microwave probe and generator.

PubMed

Bhardwaj, N; Strickland, A D; Ahmad, F; El-Abassy, M; Morgan, B; Robertson, G S M; Lloyd, D M

2010-03-01

Microwave ablation is an in situ method of tumour destruction used to treat patients with unresectable liver tumours. A new microwave generator and probe, designed to deliver high energy into solid tumours quickly has been developed at our institution. We report the results of its use in patients with unresectable liver tumours treated by a single surgeon in a single institution. Thirty-one patients with 89 unresectable liver tumours were recruited into the study and underwent microwave ablation in a single procedure. There were no post-operative complications. At a median of 24 months post ablation, 15 patients were alive with 7 patients disease free. At a median of 26 months, 8 patients were alive with tumour recurrence but only 1 with local recurrence. The remaining 7 patients with recurrence were found to have new disease at locations remote from the ablation site. Fourteen patients died of disease progression at a median survival of 15 months, with only 1 patient with local and remote tumour recurrence. Of the total numbers of tumours treated (n=89), a local tumour recurrence rate of 2% was observed. Overall median survival was 29 months with 3 year survival of 40%. Microwave tissue ablation using this novel generator and probe has a low local recurrence and complication rate. Overall survival is comparable to alternative ablation modalities and its ability to treat, even large tumours, with a single insertion of the probe makes it an extremely attractive treatment option. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Microwave device investigations

NASA Technical Reports Server (NTRS)

Choudhury, K. K. D.; Haddad, G. I.; Kwok, S. P.; Masnari, N. A.; Trew, R. J.

1972-01-01

Materials, devices and novel schemes for generation, amplification and detection of microwave and millimeter wave energy are studied. Considered are: (1) Schottky-barrier microwave devices; (2) intermodulation products in IMPATT diode amplifiers; and (3) harmonic generation using Read diode varactors.

Application of Ground Based Microwave Radiometry for Characterizing Tropical Convection

NASA Astrophysics Data System (ADS)

Renju, R.; Raju, C. S.

2016-12-01

The characterization of the microphysical and thermodynamical properties of convective events over the tropical coastal station Thiruvananthapuram (TVM, 8.5o N 76.9oE) has been carried out by utilizing multiyear Microwave Radiometer Profiler (MRP) observations. The analyses have been extended to develop a methodology to identify convective events, based on the radiometric brightness temperature (Tb) differences, at 30 GHz and 22.5 GHz channels and are compared using reflectivity and rainfall intensity deduced from concurrent and collocated disdrometer measurements. In all 84 such convections were identified using the above methodology over the station for a period of years, 2010-2013; both during pre- and post- Indian summer monsoon months and further evaluated by computing their stability indices. The occurrence of convection over this coastal station peaks in the afternoon and early morning hours with genesis, respectively, over the land and the sea. The number of occurrence of convective events are less during monsoon deficit year whereas strong and more during heavy monsoon rainfall year. These findings are further evaluated with the percentage occurrence of fractional convective clouds derived from microwave payload SAPHIR observations on Megha-Tropique satellite. Based on the analyses the frequency of occurrence of convection can be related to the monsoonal rainfall obtaining over the region. The analyses also indicate that the microwave radiometric brightness temperature of humidity channels depicts the type of convection and respond two hours prior to the occurrence of rainfall. In addition to that the multi-angle observations of microwave radiometer profiler have been utilized to study the propagation of convective systems. This study and the methodology developed for identifying convection have significance in microwave (Ka- and W-band) satellite propagation characterization since convection and precipitation are the major hindrance to satellite

Comparative evaluation of surface porosities in conventional heat polymerized acrylic resin cured by water bath and microwave energy with microwavable acrylic resin cured by microwave energy

PubMed Central

Singh, Sunint; Palaskar, Jayant N.; Mittal, Sanjeev

2013-01-01

Background: Conventional heat cure poly methyl methacrylate (PMMA) is the most commonly used denture base resin despite having some short comings. Lengthy polymerization time being one of them and in order to overcome this fact microwave curing method was recommended. Unavailability of specially designed microwavable acrylic resin made it unpopular. Therefore, in this study, conventional heat cure PMMA was polymerized by microwave energy. Aim and Objectives: This study was designed to evaluate the surface porosities in PMMA cured by conventional water bath and microwave energy and compare it with microwavable acrylic resin cured by microwave energy. Materials and Methods: Wax samples were obtained by pouring molten wax into a metal mold of 25 mm × 12 mm × 3 mm dimensions. These samples were divided into three groups namely C, CM, and M. Group C denotes conventional heat cure PMMA cured by water bath method, CM denotes conventional heat cure PMMA cured by microwave energy, M denotes specially designed microwavable acrylic denture base resin cured by microwave energy. After polymerization, each sample was scanned in three pre-marked areas for surface porosities using the optical microscope. As per the literature available, this instrument is being used for the first time to measure the porosity in acrylic resin. It is a reliable method of measuring area of surface pores. Portion of the sample being scanned is displayed on the computer and with the help of software area of each pore was measured and data were analyzed. Results: Conventional heat cure PMMA samples cured by microwave energy showed maximum porosities than the samples cured by conventional water bath method and microwavable acrylic resin cured by microwave energy. Higher percentage of porosities was statistically significant, but well within the range to be clinically acceptable. Conclusion: Within the limitations of this in-vitro study, conventional heat cure PMMA can be cured by microwave energy

Microwaves and Alzheimer's disease

PubMed Central

Zhang, Xia; Huang, Wen-Juan; Chen, Wei-Wei

2016-01-01

Alzheimer's diseases (AD) is the most common type of dementia and a neurodegenerative disease that occurs when the nerve cells in the brain die. The cause and treatment of AD remain unknown. However, AD is a disease that affects the brain, an organ that controls behavior. Accordingly, anything that can interact with the brain may affect this organ positively or negatively, thereby protecting or encouraging AD. In this regard, modern life encompasses microwaves for all issues including industrial, communications, medical and domestic tenders, and among all applications, the cell phone wave, which directly exposes the brain, continues to be the most used. Evidence suggests that microwaves may produce various biological effects on the central nervous system (CNS) and many arguments relay the possibility that microwaves may be involved in the pathophysiology of CNS disease, including AD. By contrast, previous studies have reported some beneficial cognitive effects and that microwaves may protect against cognitive impairment in AD. However, although many of the beneficial effects of microwaves are derived from animal models, but can easily be extrapolated to humans, whether microwaves cause AD is an important issue that is to be addressed in the current review. PMID:27698682

47 CFR 101.141 - Microwave modulation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 5 2013-10-01 2013-10-01 false Microwave modulation. 101.141 Section 101.141 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.141 Microwave modulation. (a) Microwave transmitters employing digital...

47 CFR 101.141 - Microwave modulation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 5 2014-10-01 2014-10-01 false Microwave modulation. 101.141 Section 101.141 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.141 Microwave modulation. (a) Microwave transmitters employing digital...

Microwave hydrology: A trilogy

NASA Technical Reports Server (NTRS)

Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

1985-01-01

Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

Development of a microwave clothes dryer: Interim report 4. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.; Lenz, R.

1996-03-01

The objective of the project is to investigate the microwave drying of clothes and to produce data that potential manufacturers can use in developing marketable microwave dryers. This is an interim report covering activities in 1994, the fifth year of the project. During 1994, three field test dryers were completed, two residential models and one commercial subscale model. All of these dryers operated at a microwave frequency of 2,450 MHz, which is the frequency of home microwave ovens and ovens used in fastfood outlets. Consequently, magnetron tubes for these high-production items are inexpensive. The residential dryers were tested according tomore » the Department of Energy protocols and were 15% more efficient than a top-of-the-line conventional electric dryer. They were also 14% faster. Extensive testing was done to assure that the hazard-detection (sniffer) system would sense degradation of the lighter and shut down the dryer before a fire could occur. Numerous butane lighters were heated to destruction in a microwave oven to examine their failure modes. Lighters were placed in microwave dryers equipped with hazard-detection systems; these systems always detected incipient problems before any fire hazard could occur.« less

Emitron: microwave diode

DOEpatents

Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

1982-05-06

The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

Correlation studies of passive and active microwave data in the marginal ice zone

NASA Technical Reports Server (NTRS)

Comiso, J. C.

1991-01-01

The microwave radiative and backscatter characteristics of sea ice in an Arctic marginal ice zone have been studied using near-simultaneous passive and active synthetic aperture radar microwave data. Intermediate-resolution multichannel passive microwave data were registered and analyzed. Passive and active microwave data generally complement each other as the two sensors are especially sensitive to different physical properties of the sea ice. In the inner pack, undeformed first-year ice is observed to have low backscatter values but high brightness temperatures while multiyear ice has generally high backscatter values and low brightness temperatures. However, in the marginal ice zone, the signature and backscatter for multiyear ice are considerably different and closer to those of first-year ice. Some floes identified by photography as snow-covered thick ice have backscatter similar to that of new ice or open water while brash ice has backscatter similar to or higher than that of ridged ice.

Microwave-Induced Interfacial Nanobubbles.

PubMed

Wang, Lei; Miao, Xiaojun; Pan, Gang

2016-11-01

A new method for generating nanobubbles via microwave irradiation was verified and quantified. AFM measurement showed that nanobubbles with diameters ranging from 200 to 600 nm were generated at a water-HOPG surface by applying microwave radiation to aqueous solutions with 9.0-30.0 mg/L dissolved oxygen. Graphite displays strong microwave absorption and transmits high thermal energy to the surface. Because of the high dielectric constant (20 °C, 80 F/m) and dielectric loss factor, water molecules have a strong ability to absorb microwave radiation. The thermal and nonthermal effects of microwave radiation made contributions to decreasing the gas solubility, thus facilitating nanobubble nucleation. The yield of nanobubbles increased about 10-fold when the irradiation time increased from 60 to 120 s at 200 W of microwave radiation. The nanobubble density increased from 0.8 to 15 μm -2 by improving the working power from 200 to 600 W. An apparent improvement in nanobubbles yield was obtained between 300 and 400 W, and the resulting temperature was 34-52 °C. When the initial dissolved oxygen increased from 11.3 to 30.0 mg/L, the density of nanobubbles increased from 1.2 to 13 μm -2 . The generation of nanobubbles could be well controlled by adjusting the gas concentration, microwave power, or irradiation time. The method may be valuable in preparing surface nanobubbles quickly and conveniently for various applications, such as catalysis, hypoxia/anoxia remediation, and templates for preparing nanoscale materials.

Microwave oxidation treatment of sewage sludge.

PubMed

Lo, Kwang V; Srinivasan, Asha; Liao, Ping H; Bailey, Sam

2015-01-01

Microwave-oxidation treatment of sewage sludge using various oxidants was studied. Two treatment schemes with a combination of hydrogen peroxide and ozone were examined: hydrogen peroxide and ozone were introduced into the sludge simultaneously, followed by microwave heating. The other involved the ozonation first, and then the resulting solution was subjected to microwave and hydrogen peroxide treatment. The set with ozonation followed by hydrogen peroxide plus microwave heating yielded higher soluble materials than those of the set with hydrogen peroxide plus ozone first and then microwave treatment. No settling was observed for all treatments in the batch operation, except ozone/microwave plus hydrogen peroxide set at 120°C. The pilot-scale continuous-flow 915 MHz microwave study has demonstrated that microwave-oxidation process is feasible for real-time industrial application. It would help in providing key data for the design of a full-scale system for treating sewage sludge and the formulation of operational protocols.

Extraction of Water from Polar Lunar Permafrost with Microwaves - Dielectric Property Measurements

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William

2009-01-01

Remote sensing indicates the presence of hydrogen rich regions associated with the lunar poles. The logical hypothesis is that there is cryogenically trapped water ice located in craters at the lunar poles. Some of the craters have been in permanent darkness for a billion years. The presence of water at the poles as well as other scientific advantages of a polar base, have influenced NASA plans for the lunar outpost. The lunar outpost has water and oxygen requirements on the order of 1 ton per year scaling up to as much as 10 tons per year. Microwave heating of the frozen permafrost has unique advantages for water extraction. Proof of principle experiments have successfully demonstrated that microwaves will couple to the cryogenic soil in a vacuum and the sublimed water vapor can be successfully captured on a cold trap. The dielectric properties of lunar soil will determine the hardware requirements for extraction processes. Microwave frequency dielectric property measurements of lunar soil simulant have been measured.

Time-of-Flight Microwave Camera

NASA Astrophysics Data System (ADS)

Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

2015-10-01

Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable “stealth” regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz-12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows “camera-like” behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum.

Time-of-Flight Microwave Camera.

PubMed

Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

2015-10-05

Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable "stealth" regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz-12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows "camera-like" behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum.

Microwave sintering of nanopowder ZnNb2O6: Densification, microstructure and microwave dielectric properties

NASA Astrophysics Data System (ADS)

Bafrooei, H. Barzegar; Nassaj, E. Taheri; Hu, C. F.; Huang, Q.; Ebadzadeh, T.

2014-12-01

High density ZnNb2O6 ceramics were successfully fabricated by microwave sintering of ZnO-Nb2O5 and ZnNb2O6 nanopowders. Phase formation, microstructure and microwave electrical properties of the microwave sintered (MS) and microwave reaction sintered (MRS) specimens were examined using X-ray diffraction, field emission scanning electron microscopy and microwave dielectric properties measurement. Specimens were sintered in a temperature range from 950 to 1075 °C for 30 min at an interval of 25 °C using a microwave furnace operated at 2.45 GHz frequency, 3 kW power. XRD pattern revealed the formation of pure columbite phase of ZnNb2O6. The SEM micrographs show grain growth and reduction in porosity of specimens with the increase in sintering temperature. Good combination of microwave dielectric properties (εr~23.6, Qf~64,300 GHz and τf~-66 ppm/°C and εr~24, Qf~75,800 GHz and τf~-64 ppm/°C) was obtained for MS- and MRS-prepared samples at 1000 °C and 1050 °C for 30 min, respectively.

Superconducting Microwave Electronics at Lewis Research Center

NASA Technical Reports Server (NTRS)

Warner, Joseph D.; Bhasin, Kul B.; Leonard, Regis F.

1991-01-01

Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

Superconducting microwave electronics at Lewis Research Center

NASA Astrophysics Data System (ADS)

Warner, Joseph D.; Bhasin, Kul B.; Leonard, Regis F.

Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

Investigating the trade-offs of microwave susceptors in energetic composites: Microwave heating versus combustion performance

NASA Astrophysics Data System (ADS)

Crane, C. A.; Pantoya, M. L.; Weeks, B. L.

2014-03-01

Recently, microwave technology has been used to ignite energetic materials when studies showed that metal powders readily absorb microwave energy. This study investigates adding a graphite susceptor to an energetic composite consisting of aluminum (Al) and iron (III) oxide (Fe2O3) and examines microwave coupling to the sample. In a companion study, the combustion of this thermite as a function of susceptor concentration was also studied to evaluate the trade-off between enhancing microwave coupling and flame propagation speed. Results show that graphite enhances microwave coupling up to 10% by mass concentration but reduces heating at higher percentages that exceed a percolation threshold. As susceptor concentrations increased greater than one mass percent, the flame propagation speed correspondingly decreased.

Bayesian Analysis of the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Jewell, Jeffrey

2007-01-01

There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background! Experiments designed to map the microwave sky are returning a flood of data (time streams of instrument response as a beam is swept over the sky) at several different frequencies (from 30 to 900 GHz), all with different resolutions and noise properties. The resulting analysis challenge is to estimate, and quantify our uncertainty in, the spatial power spectrum of the cosmic microwave background given the complexities of "missing data", foreground emission, and complicated instrumental noise. Bayesian formulation of this problem allows consistent treatment of many complexities including complicated instrumental noise and foregrounds, and can be numerically implemented with Gibbs sampling. Gibbs sampling has now been validated as an efficient, statistically exact, and practically useful method for low-resolution (as demonstrated on WMAP 1 and 3 year temperature and polarization data). Continuing development for Planck - the goal is to exploit the unique capabilities of Gibbs sampling to directly propagate uncertainties in both foreground and instrument models to total uncertainty in cosmological parameters.

Discussion on Microwave-Matter Interaction Mechanisms by In Situ Observation of "Core-Shell" Microstructure during Microwave Sintering.

PubMed

Liu, Wenchao; Xu, Feng; Li, Yongcun; Hu, Xiaofang; Dong, Bo; Xiao, Yu

2016-02-23

This research aims to deepen the understanding of the interaction mechanisms between microwave and matter in a metal-ceramic system based on in situ synchrotron radiation computed tomography. A special internal "core-shell" microstructure was discovered for the first time and used as an indicator for the interaction mechanisms between microwave and matter. Firstly, it was proved that the microwave magnetic field acted on metal particles by way of inducing an eddy current in the surface of the metal particles, which led to the formation of a "core-shell" microstructure in the metal particles. On this basis, it was proposed that the ceramic particles could change the microwave field and open a way for the microwave, thereby leading to selective heating in the region around the ceramic particles, which was verified by the fact that all the "core-shell" microstructure was located around ceramic particles. Furthermore, it was indicated that the ceramic particles would gather the microwaves, and might lead to local heating in the metal-ceramic contact region. The focusing of the microwave was proved by the quantitative analysis of the evolution rate of the "core-shell" microstructure in a different region. This study will help to reveal the microwave-matter interaction mechanisms during microwave sintering.

Increasing the Size of Microwave Popcorn

NASA Astrophysics Data System (ADS)

Smoyer, Justin

2005-03-01

Each year Americans consume approximately 17 billion quarts of popcorn. Since the 1940s, microwaves have been the heating source of choice for most. By treating the popcorn mechanism as a thermodynamic system, it has been shown mathematically and experimentally that reducing the surrounding pressure of the unpopped kernels, results in an increased volume of the kernels [Quinn et al, http://xxx.lanl.gov/abs/cond-mat/0409434 v1 2004]. In this project an alternate method of popping with the microwave was used to further test and confirm this hypothesis. Numerous experimental trials where run to test the validity of the theory. The results show that there is a significant increase in the average kernel size as well as a reduction in the number of unpopped kernels.

Microwave phase conjugation using artificial nonlinear microwave surfaces

NASA Astrophysics Data System (ADS)

Chang, Yian

1997-09-01

A new technique is developed and demonstrated to simulate nonlinear materials in the microwave and millimeter wave regime. Such materials are required to extend nonlinear optical techniques into longer wavelength areas. Using an array of antenna coupled mixers as an artificial nonlinear surface, we have demonstrated two-dimensional free space microwave phase conjugation at 10 GHz. The basic concept is to replace the weak nonlinearity of electron distribution in a crystal with the strong nonlinear V-I response of a P-N junction. This demnstration uses a three-wave mixing method with the effective nonlinear susceptibility χ(2) provided by an artificial nonlinear surface. The pump signal at 2ω (20 GHz) can be injected to the mixing elements electrically or optically. Electrical injection was first used to prove the concept of artificial nonlinear surfaces. However, due to the loss and size of microwave components, electrical injection is not practical for an array of artificial nonlinear surfaces, as would be needed in a three-dimensional free space phase conjugation setup. Therefore optical injection was implemented to carry the 2ω microwave pump signal in phase to all mixing elements. In both cases, two-dimensional free space phase conjugation was observed by directly measuring the electric field amplitude and phase distribution. The electric field wavefronts exhibited retro-directivity and auto- correction characteristics of phase conjugation. This demonstration surface also shows a power gain of 10 dB, which is desired for potential communication applications.

Controlled Microwave Heating Accelerates Rolling Circle Amplification

PubMed Central

Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

2015-01-01

Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same. PMID:26348227

Controlled Microwave Heating Accelerates Rolling Circle Amplification.

PubMed

Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

2015-01-01

Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same.

Microwave ablation devices for interventional oncology.

PubMed

Ward, Robert C; Healey, Terrance T; Dupuy, Damian E

2013-03-01

Microwave ablation is one of the several options in the ablation armamentarium for the treatment of malignancy, offering several potential benefits when compared with other ablation, radiation, surgical and medical treatment modalities. The basic microwave system consists of the generator, power distribution system and antennas. Often under image (computed tomography or ultrasound) guidance, a needle-like antenna is inserted percutaneously into the tumor, where local microwave electromagnetic radiation is emitted from the probe's active tip, producing frictional tissue heating, capable of causing cell death by coagulation necrosis. Half of the microwave ablation systems use a 915 MHz generator and the other half use a 2450 MHz generator. To date, there are no completed clinical trials comparing microwave devices head-to-head. Prospective comparisons of microwave technology with other treatment alternatives, as well as head-to-head comparison with each microwave device, is needed if this promising field will garner more widespread support and use in the oncology community.

Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

NASA Technical Reports Server (NTRS)

Lawrence, Richard J. (Technical Monitor); Wentz, Frank J.

2003-01-01

During the three years of fundin& we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

NASA Technical Reports Server (NTRS)

Wentz, Frank J.; Lawrence, Richard J. (Technical Monitor)

2003-01-01

During the three years of finding, we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

Cosmic Microwave Background Data Analysis

NASA Astrophysics Data System (ADS)

Paykari, Paniez; Starck, Jean-Luc Starck

2012-03-01

that the highest power fluctuations occur at scales of about one degree. A number of ground-based interferometers provided measurements of the fluctuations with higher accuracy over the next three years, including the Very Small Array [16], Degree Angular Scale Interferometer (DASI) [61], and the Cosmic Background Imager (CBI) [78]. DASI was the first to detect the polarization of the CMB and the CBI provided the first E-mode polarization spectrum with compelling evidence that it is out of phase with the T-mode spectrum. In June 2001, NASA launched its second CMB mission (after COBE), Wilkinson Microwave Anisotropy Explorer (WMAP) [44], to make much more precise measurements of the CMB sky. WMAP measured the differences in the CMB temperature across the sky creating a full-sky map of the CMB in five different frequency bands. The mission also measured the CMB's E-mode and the foreground polarization. As of October 2010, the WMAP spacecraft has ended its mission after nine years of operation. Although WMAP provided very accurate measurements of the large angular-scale fluctuations in the CMB, it did not have the angular resolution to cover the smaller-scale fluctuations that had been observed by previous ground-based interferometers. A third space mission, the Planck Surveyor [1], was launched by ESA* in May 2009 to measure the CMB on smaller scales than WMAP, as well as making precise measurements of the polarization of CMB. Planck represents an advance over WMAP in several respects: it observes in higher resolution, hence allowing one to probe the CMB power spectrum to smaller scales; it has a higher sensitivity and observes in nine frequency bands rather than five, hence improving the astrophysical foreground models. The mission has a wide variety of scientific aims, including: (1) detecting the total intensity/polarization of the primordial CMB anisotropies; (2) creating a galaxy-cluster catalogue through the Sunyaev-Zel'dovich (SZ) effect [93]; (3) observing the

Physics of the Microwave Oven

ERIC Educational Resources Information Center

Vollmer, Michael

2004-01-01

This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

Time-of-Flight Microwave Camera

PubMed Central

Charvat, Gregory; Temme, Andrew; Feigin, Micha; Raskar, Ramesh

2015-01-01

Microwaves can penetrate many obstructions that are opaque at visible wavelengths, however microwave imaging is challenging due to resolution limits associated with relatively small apertures and unrecoverable “stealth” regions due to the specularity of most objects at microwave frequencies. We demonstrate a multispectral time-of-flight microwave imaging system which overcomes these challenges with a large passive aperture to improve lateral resolution, multiple illumination points with a data fusion method to reduce stealth regions, and a frequency modulated continuous wave (FMCW) receiver to achieve depth resolution. The camera captures images with a resolution of 1.5 degrees, multispectral images across the X frequency band (8 GHz–12 GHz), and a time resolution of 200 ps (6 cm optical path in free space). Images are taken of objects in free space as well as behind drywall and plywood. This architecture allows “camera-like” behavior from a microwave imaging system and is practical for imaging everyday objects in the microwave spectrum. PMID:26434598

Microwave remote sensing from space

NASA Technical Reports Server (NTRS)

Carver, K. R.; Elachi, C.; Ulaby, F. T.

1985-01-01

Spaceborne microwave remote sensors provide perspectives of the earth surface and atmosphere which are of unique value in scientific studies of geomorphology, oceanic waves and topography, atmospheric water vapor and temperatures, vegetation classification and stress, ice types and dynamics, and hydrological characteristics. Microwave radars and radiometers offer enhanced sensitivities to the geometrical characteristics of the earth's surface and its cover, to water in all its forms - soil and vegetation moisture, ice, wetlands, oceans, and atmospheric water vapor, and can provide high-resolution imagery of the earth's surface independent of cloud cover or sun angle. A brief review of the historical development and principles of active and passive microwave remote sensing is presented, with emphasis on the unique characteristics of the information obtainable in the microwave spectrum and the value of this information to global geoscientific studies. Various spaceborne microwave remote sensors are described, with applications to geology, planetology, oceanography, glaciology, land biology, meteorology, and hydrology. A discussion of future microwave remote sensor technological developments and challenges is presented, along with a summary of future missions being planned by several countries.

Emerging Trends in Microwave Processing of Spices and Herbs.

PubMed

Rahath Kubra, Ismail; Kumar, Devender; Jagan Mohan Rao, Lingamallu

2016-10-02

Today, spices are integral part of our food as they provide sensory attributes such as aroma, color, flavour and taste to food. Further their antimicrobial, antioxidant, pharmaceutical and nutritional properties are also well known. Since spices are seasonal so their availability can be extended year round by adopting different preservation techniques. Drying and extraction are most important methods for preservation and value addition to spices. There are different techniques for drying of spices with their own advantages and limitations. A novel, non-conventional technique for drying of spices is use of microwave radiation. This technique proved to be very rapid, and also provide a good quality product. Similarly, there are a number of non-conventional extraction methods in use that are all, in principle, solid-liquid extractions but which introduce some form of additional energy to the process in order to facilitate the transfer of analytes from sample to solvent. This paper reviews latest advances in the use of microwave energy for drying of spices and herbs. Also, the review describes the potential application of microwave energy for extraction of essential oil/bioactive components from spices and herbs and the advantages of microwave-assisted process over the other extraction processes generally employed for extraction. It also showcases some recent research results on microwave drying/extraction from spices and herbs.

Microwave Fun: User-Friendly Recipe Cards.

ERIC Educational Resources Information Center

Bergstrom, Tom; And Others

1995-01-01

This article explains how a 12-year-old boy with profound mental retardation and autistic behaviors, living in a group home, was taught to follow number- and color-coded directions so that he could independently cook his own meals in a microwave oven. The article covers materials used, the skills taught, adaptations for classroom use, and safety…

Bioeffects of microwave--a brief review.

PubMed

Banik, S; Bandyopadhyay, S; Ganguly, S

2003-04-01

Since the 18th century scientists have been intrigued by the interaction of electromagnetic fields (EMFs) and various life processes. Attention has been focussed on EMFs in different frequency ranges, of which microwave frequency range forms an important part. Microwaves are part of the electromagnetic spectrum and are considered to be that radiation ranging in frequency from 300 million cycles per second (300 MHz) to 300 billion cycles per second (300 GHz), which correspond to a wavelength range of 1 m down to 1 mm. This nonionising electromagnetic radiation is absorbed at molecular level and manifests as changes in vibrational energy of the molecules or heat (Microwaves irradiating the community, Hidden hazards, Bantan Books publisher, Australia, 1991). Identifying and evaluating the biological effects of microwaves have been complex and controversial. Because of the paucity of information on the mechanism of interaction between microwave and biological systems, there has been a persistent view in physical and engineering sciences, that microwave fields are incapable of inducing bioeffects other than by heating (Health Physics 61 (1991) 3). Of late, the nonthermal effects of microwaves on tissue responses are being documented (Physiol. Rev. 61 (1981) 435; Annals of New York Acad. Sci. 247 (1975) 232; J. Microwave Power 14 (1979) 351; Bioelectromagnetics 7 (1986a) 45; Bioelectromagnetics 7 (1986b) 315; Biologic Effects and Health Hazards of Microwave Radiation, Warsaw, Polish Medical Publication (1974) 289; Biologic Effects and Health hazards of the microwave Radiation, Warsaw, Polish Medical Publication (1974) 22; Multidisciplinory perspectives in event-related brain potential research, Washington DC, US Environmental Protection Agency, (1978) 444). The present article is an attempt to familiarise the reader with pertinent information regarding the effects, mainly athermal, of microwave irradiation on biologic systems, especially microorganisms.

Thin-Film Ferroelectric Tunable Microwave Devices Being Developed

NASA Technical Reports Server (NTRS)

VanKeuls, Frederick W.

1999-01-01

Electronically tunable microwave components have become the subject of intense research efforts in recent years. Many new communications systems would greatly benefit from these components. For example, planned low Earth orbiting satellite networks have a need for electronically scanned antennas. Thin ferroelectric films are one of the major technologies competing to fill these applications. When a direct-current (dc) voltage is applied to ferroelectric film, the dielectric constant of the film can be decreased by nearly an order of magnitude, changing the high-frequency wavelength in the microwave device. Recent advances in film growth have demonstrated high-quality ferroelectric thin films. This technology may allow microwave devices that have very low power and are compact, lightweight, simple, robust, planar, voltage tunable, and affordable. The NASA Lewis Research Center has been designing, fabricating, and testing proof-of-concept tunable microwave devices. This work, which is being done in-house with funding from the Lewis Director's Discretionary Fund, is focusing on introducing better microwave designs to utilize these materials. We have demonstrated Ku- and K-band phase shifters, tunable local oscillators, tunable filters, and tunable diplexers. Many of our devices employ SrTiO3 as the ferroelectric. Although it is one of the more tunable and easily grown ferroelectrics, SrTiO3 must be used at cryogenic temperatures, usually below 100 K. At these temperatures, we frequently use high-temperature superconducting thin films of YBa2Cu3O7-8 to carry the microwave signals. However, much of our recent work has concentrated on inserting room-temperature ferroelectric thin films, such as BaxSr1- xTiO3 into these devices. The BaxSr1-xTiO3 films are used in conjuction with normal metal conductors, such as gold.

Relic keV sterile neutrinos and reionization.

PubMed

Biermann, Peter L; Kusenko, Alexander

2006-03-10

A sterile neutrino with a mass of several keV can account for cosmological dark matter, as well as explain the observed velocities of pulsars. We show that x rays produced by the decays of these relic sterile neutrinos can boost the production of molecular hydrogen, which can speed up the cooling of gas and the early star formation, which can, in turn, lead to a reionization of the Universe at a high enough redshift to be consistent with the Wilkinson Microwave Anisotropy Probe results.

Microwave interconnection

NASA Astrophysics Data System (ADS)

Fry, P. E.

1993-06-01

A limited evaluation was made of two commonly found microwave interconnections: microstrip-to-microstrip and coaxial-to-microstrip. The evaluation attempted to select the interconnection technique which worked best for the particular interface type. Short ribbon wires worked best for the microstrip-to-microstrip interconnection. A published method of compensating the microstrip conductor had the best performance for the coaxial-to-microstrip interconnection. The work was conducted under the Microwave Technology Process Capability Assurance Program at Allied-Signal Inc., Kansas City Division.

Hybrid microwave/conventionally heated calorimeter

NASA Astrophysics Data System (ADS)

Binner, Jon G. P.; Price, Duncan M.; Reading, Mike; Vaidhyanathan, Bala

2005-06-01

The design and construction of a calorimeter in which the specimen may be heated by microwave radiation and/or hot air is described. The apparatus was used to examine the effect of microwave radiation on the melting of benzil (89°C) and the solid-state phase transition of silver iodide (147°C). Reproducibility of transition temperature determinations were within ±1°C. No changes were observed for benzil but silver iodide exhibited an apparent reduction in transition temperature to around 120°C in the presence of microwaves, which increased with the level of microwave irradiation.

Optimisation of microwave-assisted processing in production of pineapple jam

NASA Astrophysics Data System (ADS)

Ismail, Nur Aisyah Mohd; Abdullah, Norazlin; Muhammad, Norhayati

2017-10-01

Pineapples are available all year round since they are unseasonal fruits. Due to the continuous harvesting of the fruit, the retailers and farmers had to find a solution such as the processing of pineapple into jam, to treat the unsuccessfully sold pineapples. The direct heating of pineapple puree during the production of pineapple jam can cause over degradation of quality of the fresh pineapple. Thus, this study aims to optimise the microwave-assisted processing conditions for producing pineapple jam which could reduce water activity and meets minimum requirement for pH and total soluble solids contents of fruit jam. The power and time of the microwave processing were chosen as the factors, while the water activity, pH and total soluble solids (TSS) content of the pineapple jam were determined as responses to be optimised. The microwave treatment on the pineapple jam was able to give significant effect on the water activity and TSS content of the pineapple jam. The optimum power and time for the microwave processing of pineapple jam is 800 Watt and 8 minutes, respectively. The use of domestic microwave oven for the pineapple jam production results in acceptable pineapple jam same as conventional fruit jam sold in the marketplace.

A New Automated Microwave Heating Process for Cooking and Pasteurization of Microwaveable Foods Containing Raw Meats

USDA-ARS?s Scientific Manuscript database

A new microwave heating process was developed for cooking microwaveable foods containing raw meats. A commercially available inverter-based microwave oven was modified for pasteurization of mechanically tenderized beef, inoculated with Escherichia coli O157:H7 (~ 5 log cfu/g) and packaged in a 12 o...

Microfabricated Microwave-Integrated Surface Ion Trap

NASA Astrophysics Data System (ADS)

Revelle, Melissa C.; Blain, Matthew G.; Haltli, Raymond A.; Hollowell, Andrew E.; Nordquist, Christopher D.; Maunz, Peter

2017-04-01

Quantum information processing holds the key to solving computational problems that are intractable with classical computers. Trapped ions are a physical realization of a quantum information system in which qubits are encoded in hyperfine energy states. Coupling the qubit states to ion motion, as needed for two-qubit gates, is typically accomplished using Raman laser beams. Alternatively, this coupling can be achieved with strong microwave gradient fields. While microwave radiation is easier to control than a laser, it is challenging to precisely engineer the radiated microwave field. Taking advantage of Sandia's microfabrication techniques, we created a surface ion trap with integrated microwave electrodes with sub-wavelength dimensions. This multi-layered device permits co-location of the microwave antennae and the ion trap electrodes to create localized microwave gradient fields and necessary trapping fields. Here, we characterize the trap design and present simulated microwave performance with progress towards experimental results. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

Method and apparatus for selectively annealing heterostructures using microwave

NASA Technical Reports Server (NTRS)

Atwater, Harry A. (Inventor); Brain, Ruth A. (Inventor); Barmatz, Martin B. (Inventor)

1998-01-01

The present invention discloses a process for selectively annealing heterostructures using microwaves. A heterostructure, comprised of a material having higher microwave absorption and a material having lower microwave absorption, is exposed to microwaves in the cavity. The higher microwave absorbing material absorbs the microwaves and selectively heats while the lower microwave absorbing material absorbs small amounts of microwaves and minimally heats. The higher microwave absorbing material is thereby annealed onto the less absorbing material which is thermally isolated.

Method and apparatus for selectively annealing heterostructures using microwaves

NASA Technical Reports Server (NTRS)

Atwater, Harry A. (Inventor); Brain, Ruth A. (Inventor); Barmatz, Martin B. (Inventor)

1998-01-01

The present invention discloses a process for selectively annealing heterostructures using microwaves. A heterostructure, comprised of a material having higher microwave absorption and a material having lower microwave absorption, is exposed to microwaves in the cavity. The higher microwave absorbing material absorbs the microwaves and selectively heats while the lower microwave absorbing material absorbs small amounts of microwaves and minimally heats. The higher microwave absorbing material is thereby annealed onto the less absorbing material which is thermally isolated.

Scanning tip microwave near field microscope

DOEpatents

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

1998-01-01

A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

Microwave Sterilization and Depyrogenation System

NASA Technical Reports Server (NTRS)

Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

2009-01-01

A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time

Pyrolysis of tyre powder using microwave thermogravimetric analysis: Effect of microwave power.

PubMed

Song, Zhanlong; Yang, Yaqing; Zhou, Long; Zhao, Xiqiang; Wang, Wenlong; Mao, Yanpeng; Ma, Chunyuan

2017-02-01

The pyrolytic characteristics of tyre powder treated under different microwave powers (300, 500, and 700 W) were studied via microwave thermogravimetric analysis. The product yields at different power levels were studied, along with comparative analysis of microwave pyrolysis and conventional pyrolysis. The feedstock underwent preheating, intense pyrolysis, and final pyrolysis in sequence. The main and secondary weight loss peaks observed during the intense pyrolysis stage were attributed to the decomposition of natural rubbers and synthetic rubbers, respectively. The total mass loss rates, bulk temperatures, and maximum temperatures were distinctively higher at higher powers. However, the maximum mass loss rate (0.005 s -1 ), the highest yields of liquid product (53%), and the minimum yields of residual solid samples (43.83%) were obtained at 500 W. Compared with conventional pyrolysis, microwave pyrolysis exhibited significantly different behaviour with faster reaction rates, which can decrease the decomposition temperatures of both natural and synthetic rubber by approximately 110 °C-140 °C.

Microwave signatures of ice hydrometeors from ground-based observations above Summit, Greenland

DOE PAGES

Pettersen, Claire; Bennartz, Ralf; Kulie, Mark S.; ...

2016-04-15

Multi-instrument, ground-based measurements provide unique and comprehensive data sets of the atmosphere for a specific location over long periods of time and resulting data compliment past and existing global satellite observations. Our paper explores the effect of ice hydrometeors on ground-based, high-frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland, from 2010 to 2013. Furthermore, data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m -2more » or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high-frequency microwave channels: 90, 150, and 225GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. Then, this measured ice signature was compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single-scattering properties for several ice habits. Furthermore, initial model results compare well against the 4 years of summer season isolated ice signature in the high-frequency microwave channels.« less

A Robust, Microwave Rain Gauge

NASA Astrophysics Data System (ADS)

Mansheim, T. J.; Niemeier, J. J.; Kruger, A.

2008-12-01

Researchers at The University of Iowa have developed an all-electronic rain gauge that uses microwave sensors operating at either 10 GHz or 23 GHz, and measures the Doppler shift caused by falling raindrops. It is straightforward to interface these sensors with conventional data loggers, or integrate them into a wireless sensor network. A disadvantage of these microwave rain gauges is that they consume significant power when they are operating. However, this may be partially negated by using data loggers' or sensors networks' sleep-wake-sleep mechanism. Advantages of the microwave rain gauges are that one can make them very robust, they cannot clog, they don't have mechanical parts that wear out, and they don't have to be perfectly level. Prototype microwave rain gauges were collocated with tipping-bucket rain gauges, and data were collected for two seasons. At higher rain rates, microwave rain gauge measurements compare well with tipping-bucket measurements. At lower rain rates, the microwave rain gauges provide more detailed information than tipping buckets, which quantize measurement typically in 1 tip per 0.01 inch, or 1 tip per mm of rainfall.

Apparatus and method for microwave processing of materials

DOEpatents

Johnson, A.C.; Lauf, R.J.; Bible, D.W.; Markunas, R.J.

1996-05-28

Disclosed is a variable frequency microwave heating apparatus designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency heating apparatus is used in the method of the present invention to monitor the resonant processing frequency within the furnace cavity depending upon the material, including the state thereof, from which the workpiece is fabricated. The variable frequency microwave heating apparatus includes a microwave signal generator and a high-power microwave amplifier or a microwave voltage-controlled oscillator. A power supply is provided for operation of the high-power microwave oscillator or microwave amplifier. A directional coupler is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 10 figs.

A review of applications of microwave radiometry to oceanography

NASA Technical Reports Server (NTRS)

Wilheit, T. T., Jr.

1978-01-01

Following a review of the essential physics of microwave radiative transfer, oceanographic applications of this background physics are discussed using data from electrically scanning microwave radiometers on the Nimbus 5 and 6 satellites operating at 1.55-cm and 8-mm wavelengths, respectively. These data are interpreted in terms of rain rate, ice coverage, and first-year versus multiyear ice determination. It is shown that multifrequency radiometer measurements make it possible to separate the surface and atmospheric effects and to obtain useful measurements of sea surface temperature, surface wind speed, and atmospheric parameters along with improved measurements of rain and ice.

Microwave Radiative Transfer: Theory and Applications

NASA Astrophysics Data System (ADS)

Wilheit, T. T.

2006-12-01

The same physical laws govern visible, infrared and microwave radiative transfer. However, frequency dependence of the Planck function and of the properties of geophysically important materials create apparent differences. The applicability of the Rayleigh-Jeans to most of the microwave spectrum is a convenience, and makes it easier to illustrate some physical principles, but is of very little fundamental importance. Line widths of gaseous constituents are determined by collision frequencies and are of the order of 1 GHz throughout the troposphere in the visible, infrared and microwave portions of the spectrum. However, it is easy to make a radiometer that has a bandwidth small compared to this width in the microwave portion of the spectrum and significantly more difficult in the infrared and visible. As a result, computations in the microwave are monochromatic (or very close to it). In the microwave portion of the spectrum there is no need for elaborate band models. Clouds are a fundamental difference because the opacity of most clouds is very high in the visible and infrared and fairly small in the microwave. This quantitative difference necessitates qualitative differences in approach. Probably, the most counter-intuitive differences between the microwave regions and shorter wavelengths result from the preponderance of highly reflective surfaces in the microwave. The oceans reflect on the order of 50% but the details depend strongly on frequency, polarization and view angle. The large glaciers of Greenland and Antarctica are also highly reflective but less dependant on view angle and polarization. This high reflectivity means that introducing an absorber into the atmosphere at a temperature colder than the surface temperature will, nevertheless increase the observed radiance. This has fundamental importance for the retrieval of constituents from the atmosphere. Even over land surfaces, the observed radiance in microwave window channels depends more on the

Phenomenology of microwave coupling, part 1

NASA Astrophysics Data System (ADS)

King, R. J.; Breakall, J. K.; Hudson, H. G.; Morrison, J. J.; McGevna, V. G.; Kunz, K. S.; Ludwigsen, A. P.; Gnade, D. K.

1984-11-01

Advances in the development of high power microwave sources have increased the potential for future deployment of microwave weapons. A key ingredient in being able to predict the vulnerability of military systems to such threats involves understanding the phenomenology of how electromagnetic energy couples into cavity like objects, or the so called back door coupling. A similar but much longer standing problem is that of nuclear electromagnetic pulses (EMP) in which the frequencies extend up to several hundreds of MHz. However, compared to EMP coupling, microwave coupling is distinctively different because the wavelength is comparable to the size of the ports of entry. Coupling paths can be highly resonant at certain microwave frequencies, making the shielding against microwave threats difficult. The initial efforts at Lawrence Livermore National Laboratory to study the phenomenology of back door coupling at the low microwave frequencies (up to 2.5 GHz) are summarized.

Microwave experiments on Prairie View Rotamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, R. J.; Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031; Xu, M.

2015-05-15

A 6 kW/2.45 GHz microwave system has been added on Prairie View Rotamak, and a series of experiments with microwave heating in both O-mode and X-mode configurations have been performed. Effective ionization of hydrogen in the two configurations is observed when filling pressure of the hydrogen gas is under p{sub f}=0.1 Pa. Clear oscillations in plasma current I{sub p} and magnetic field B{sub R} are excited when microwaves are injected into plasma in the X-mode configuration. The higher the injected microwave power, the sooner the emergence of the magnetic oscillations in B{sub R}, which implies the microwave may have decreased the elongationmore » of the plasma. In the experiments, the efficiency of the current drive mechanism due to the injected microwave is about 0.2 kA/kW.« less

Energy Efficient Microwave Hybrid Processing of Lime for Cement, Steel, and Glass Industries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fall, Morgana L; Yakovlev, Vadim; Sahi, Catherine

2012-02-10

uptake of MAT in the US lime industry. This estimate showed that 7.3 TBTU/year could be saved, with reduction of 270 MMlbs of CO2 emissions, and $29 MM/year in economic savings. Taking into account estimates for MAT implementation in the US cement industry, an additional 39 TBTU/year, 3 Blbs of CO2 and $155 MM/year could be saved. One of the main remaining barriers to commercialization of MAT for the lime and cement industries is the sheer size of production. Through this project, it was realized that a production size MAT rotary calciner was not feasible, and a different approach was adapted. The concept of a microwave post heat section located in the upper portion of the cooler was devised and appears to be a more realistic approach for MAT implementation. Commercialization of this technology will require (1) continued pilot scale calcining demonstrations, (2) involvement of lime kiln companies, and (3) involvement of an industrial microwave equipment provider. An initial design concept for a MAT post-heat treatment section was conceived as a retrofit into the cooler sections of existing lime rotary calciners with a 1.4 year payback. Retrofitting will help spur implementation of this technology, as the capital investment will be minimal for enhancing the efficiency of current rotary lime kilns. Retrofits would likely be attractive to lime manufacturers, as the purchase of a new lime kiln is on the order of a $30 million dollar investment, where as a MAT retrofit is estimated on the order of $1 million. The path for commercialization lies in partnering with existing lime kiln companies, who will be able to implement the microwave post heat sections in existing and new build kilns. A microwave equipment provider has been identified, who would make up part of the continued development and commercialization team.« less

MICROWAVES IN ORGANIC SYNTHESIS

EPA Science Inventory

The effect of microwaves, a non-ionizing radiation, on organic reactions is described both in polar solvents and under solvent-free conditions. The special applications are highlighted in the context of solventless organic synthesis which involve microwave (MW) exposure of neat r...

Microwave Detection With Single-Band Metamaterials For High Power Microwave Weapons

DTIC Science & Technology

2017-12-01

DETECTION WITH SINGLE-BAND METAMATERIALS FOR HIGH POWER MICROWAVE WEAPONS by Edward V. Wulff December 2017 Thesis Advisor: Dragoslav Grbovic...3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE MICROWAVE DETECTION WITH SINGLE-BAND METAMATERIALS FOR HIGH POWER...IRB number ____N/A____. 12a. DISTRIBUTION / AVAILABILITY STATEMENT Approved for public release. Distribution is unlimited. 12b. DISTRIBUTION

Comparison of microwave hydrodistillation and solvent-free microwave extraction of essential oil from Melaleuca leucadendra Linn

NASA Astrophysics Data System (ADS)

Ismanto, A. W.; Kusuma, H. S.; Mahfud, M.

2017-12-01

The comparison of solvent-free microwave extraction (SFME) and microwave hydrodistillation (MHD) in the extraction of essential oil from Melaleuca leucadendra Linn. was examined. Dry cajuput leaves were used in this study. The purpose of this study is also to determine optimal condition (microwave power). The relative electric consumption of SFME and MHD methods are both showing 0,1627 kWh/g and 0,3279 kWh/g. The results showed that solvent-free microwave extraction methods able to reduce energy consumption and can be regarded as a green technique for extraction of cajuput oil.

Active microwaves

NASA Technical Reports Server (NTRS)

Evans, D.; Vidal-Madjar, D.

1994-01-01

Research on the use of active microwaves in remote sensing, presented during plenary and poster sessions, is summarized. The main highlights are: calibration techniques are well understood; innovative modeling approaches have been developed which increase active microwave applications (segmentation prior to model inversion, use of ERS-1 scatterometer, simulations); polarization angle and frequency diversity improves characterization of ice sheets, vegetation, and determination of soil moisture (X band sensor study); SAR (Synthetic Aperture Radar) interferometry potential is emerging; use of multiple sensors/extended spectral signatures is important (increase emphasis).

Microwave fluid flow meter

DOEpatents

Billeter, Thomas R.; Philipp, Lee D.; Schemmel, Richard R.

1976-01-01

A microwave fluid flow meter is described utilizing two spaced microwave sensors positioned along a fluid flow path. Each sensor includes a microwave cavity having a frequency of resonance dependent upon the static pressure of the fluid at the sensor locations. The resonant response of each cavity with respect to a variation in pressure of the monitored fluid is represented by a corresponding electrical output which can be calibrated into a direct pressure reading. The pressure drop between sensor locations is then correlated as a measure of fluid velocity. In the preferred embodiment the individual sensor cavities are strategically positioned outside the path of fluid flow and are designed to resonate in two distinct frequency modes yielding a measure of temperature as well as pressure. The temperature response can then be used in correcting for pressure responses of the microwave cavity encountered due to temperature fluctuations.

Scanning tip microwave near field microscope

DOEpatents

Xiang, X.D.; Schultz, P.G.; Wei, T.

1998-10-13

A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an end wall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity. 17 figs.

TRMM Microwave Imager (TMI) Updates for Final Data Version Release

NASA Technical Reports Server (NTRS)

Kroodsma, Rachael A; Bilanow, Stephen; Ji, Yimin; McKague, Darren

2017-01-01

The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) dataset released by the Precipitation Processing System (PPS) will be updated to a final version within the next year. These updates are based on increased knowledge in recent years of radiometer calibration and sensor performance issues. In particular, the Global Precipitation Measurement (GPM) Microwave Imager (GMI) is used as a model for many of the TMI version updates. This paper discusses four aspects of the TMI data product that will be improved: spacecraft attitude, calibration and quality control, along-scan bias corrections, and sensor pointing accuracy. These updates will be incorporated into the final TMI data version, improving the quality of the data product and ensuring accurate geophysical parameters can be derived from TMI.

High-power microwave LDMOS transistors for wireless data transmission technologies (Review)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuznetsov, E. V., E-mail: E.Kouzntsov@tcen.ru; Shemyakin, A. V.

The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10-15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceiversmore » for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).« less

Atmospheric microwave refractivity and refraction

NASA Technical Reports Server (NTRS)

Yu, E.; Hodge, D. B.

1980-01-01

The atmospheric refractivity can be expressed as a function of temperature, pressure, water vapor content, and operating frequency. Based on twenty-year meteorological data, statistics of the atmospheric refractivity were obtained. These statistics were used to estimate the variation of dispersion, attenuation, and refraction effects on microwave and millimeter wave signals propagating along atmospheric paths. Bending angle, elevation angle error, and range error were also developed for an exponentially tapered, spherical atmosphere.

Disinfection of Wastewater by Microwaves.

DTIC Science & Technology

1980-01-01

used. Thermophilic B. stearothermophilus cells were used to try to determine if the mechanism of destruction was thermal. The microwave oven was set at...curve for E. coli B cells heated in a microwave oven temperature programed for 600 C ...... ............ 8 7. Survivor curve for B. stearothermophilus ...ATCC 12980 cells heated in a microwave oven temperature programed for 600 C. 98. Survivor curve for B. stearothermophilus AICC 12980 ........ 9 9

Microwave vision for robots

NASA Technical Reports Server (NTRS)

Lewandowski, Leon; Struckman, Keith

1994-01-01

Microwave Vision (MV), a concept originally developed in 1985, could play a significant role in the solution to robotic vision problems. Originally our Microwave Vision concept was based on a pattern matching approach employing computer based stored replica correlation processing. Artificial Neural Network (ANN) processor technology offers an attractive alternative to the correlation processing approach, namely the ability to learn and to adapt to changing environments. This paper describes the Microwave Vision concept, some initial ANN-MV experiments, and the design of an ANN-MV system that has led to a second patent disclosure in the robotic vision field.

Microwave coupler and method

DOEpatents

Holcombe, C.E.

1984-11-29

The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

Microwave coupler and method

DOEpatents

Holcombe, Cressie E.

1985-01-01

The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

Mechanism for microwave heating of 1-(4'-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy.

PubMed

Tasei, Yugo; Yamakami, Takuya; Kawamura, Izuru; Fujito, Teruaki; Ushida, Kiminori; Sato, Motoyasu; Naito, Akira

2015-05-01

Microwave heating is widely used to accelerate organic reactions and enhance the activity of enzymes. However, the detailed molecular mechanism for the effect of microwave on chemical reactions is not yet fully understood. To investigate the effects of microwave heating on organic compounds, we have developed an in situ microwave irradiation NMR spectroscopy. (1)H NMR spectra of 1-(4'-cyanophenyl)-4-propylcyclohexane (PCH3) in the liquid crystalline and isotropic phases were observed under microwave irradiation. When the temperature was regulated at slightly higher than the phase transition temperature (Tc=45 °C) under a gas flow temperature control system, liquid crystalline phase mostly changed to the isotropic phase. Under microwave irradiation and with the gas flow temperature maintained at 20 °C, which is 25 °C below the Tc, the isotropic phase appeared stationary as an approximately 2% fraction in the liquid crystalline phase. The temperature of the liquid crystalline state was estimated to be 38 °C according to the line width, which is at least 7 °C lower than the Tc. The temperature of this isotropic phase should be higher than 45 °C, which is considered to be a non-equilibrium local heating state induced by microwave irradiation. Microwaves at a power of 195 W were irradiated to the isotropic phase of PCH3 at 50 °C and after 2 min, the temperature reached 220 °C. The temperature of PCH3 under microwave irradiation was estimated by measurement of the chemical shift changes of individual protons in the molecule. These results demonstrate that microwave heating generates very high temperature within a short time using an in situ microwave irradiation NMR spectrometer. Copyright © 2015 Elsevier Inc. All rights reserved.

Piezoelectric-tuned microwave cavity for absorption spectrometry

DOEpatents

Leskovar, Branko; Buscher, Harold T.; Kolbe, William F.

1978-01-01

Gas samples are analyzed for pollutants in a microwave cavity that is provided with two highly polished walls. One wall of the cavity is mechanically driven with a piezoelectric transducer at a low frequency to tune the cavity over a band of microwave frequencies in synchronism with frequency modulated microwave energy applied to the cavity. Absorption of microwave energy over the tuned frequencies is detected, and energy absorption at a particular microwave frequency is an indication of a particular pollutant in the gas sample.

Apparatus and method for microwave processing of materials

DOEpatents

Johnson, Arvid C.; Lauf, Robert J.; Bible, Don W.; Markunas, Robert J.

1996-01-01

A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency heating apparatus (10) is used in the method of the present invention to monitor the resonant processing frequency within the furnace cavity (34) depending upon the material, including the state thereof, from which the workpiece (36) is fabricated. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a microwave voltage-controlled oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Modeling and prediction of extraction profile for microwave-assisted extraction based on absorbed microwave energy.

PubMed

Chan, Chung-Hung; Yusoff, Rozita; Ngoh, Gek-Cheng

2013-09-01

A modeling technique based on absorbed microwave energy was proposed to model microwave-assisted extraction (MAE) of antioxidant compounds from cocoa (Theobroma cacao L.) leaves. By adapting suitable extraction model at the basis of microwave energy absorbed during extraction, the model can be developed to predict extraction profile of MAE at various microwave irradiation power (100-600 W) and solvent loading (100-300 ml). Verification with experimental data confirmed that the prediction was accurate in capturing the extraction profile of MAE (R-square value greater than 0.87). Besides, the predicted yields from the model showed good agreement with the experimental results with less than 10% deviation observed. Furthermore, suitable extraction times to ensure high extraction yield at various MAE conditions can be estimated based on absorbed microwave energy. The estimation is feasible as more than 85% of active compounds can be extracted when compared with the conventional extraction technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

A microwave field-driven transistor-like skyrmionic device with the microwave current-assisted skyrmion creation

NASA Astrophysics Data System (ADS)

Xia, Jing; Huang, Yangqi; Zhang, Xichao; Kang, Wang; Zheng, Chentian; Liu, Xiaoxi; Zhao, Weisheng; Zhou, Yan

2017-10-01

Magnetic skyrmion is a topologically protected domain-wall structure at nanoscale, which could serve as a basic building block for advanced spintronic devices. Here, we propose a microwave field-driven skyrmionic device with the transistor-like function, where the motion of a skyrmion in a voltage-gated ferromagnetic nanotrack is studied by micromagnetic simulations. It is demonstrated that the microwave field can drive the motion of a skyrmion by exciting the propagating spin waves, and the skyrmion motion can be governed by a gate voltage. We also investigate the microwave current-assisted creation of a skyrmion to facilitate the operation of the transistor-like skyrmionic device on the source terminal. It is found that the microwave current with an appropriate frequency can reduce the threshold current density required for the creation of a skyrmion from the ferromagnetic background. The proposed transistor-like skyrmionic device operated with the microwave field and current could be useful for building future skyrmion-based circuits.

CHARGING OF DEVICES BY MICROWAVE POWER BEAMING

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A. (Inventor)

2005-01-01

A system for providing wireless, charging power and/or primary power to electronic/electrical devices is described whereby microwave energy is employed. Microwave energy is focused by a power transmitter comprising one or more adaptively-phased microwave array emitters onto a device to be charged. Rectennas within the device to be charged receive and rectify the microwave energy and use it for battery charging and/or for primary power. A locator signal generated by the device to be charged is analyzed by the system to determine the location of the device to be charged relative to the microwave array emitters, permitting thc microwave energy to be directly specifically towards the device to be charged. Backscatter detectors respond to backscatter energy reflected off of any obstacle between the device to be charged and the microwave array emitters. Power to any obstructed microwave array emitter is reduced until the obstruction is removed. Optionally, data can be modulated onto microwave energy beams produced by the array emitter and demodulated by the device, thereby providing means of data communication from the power transmitter to the device. Similarly, data can be modulated onto the locator signal and demodulated in the power transmitter, thereby providing means of data communication from the device to the power transmitter.

Microwave assisted centrifuge and related methods

DOEpatents

Meikrantz, David H [Idaho Falls, ID

2010-08-17

Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

Photon Statistics of Propagating Thermal Microwaves.

PubMed

Goetz, J; Pogorzalek, S; Deppe, F; Fedorov, K G; Eder, P; Fischer, M; Wulschner, F; Xie, E; Marx, A; Gross, R

2017-03-10

In experiments with superconducting quantum circuits, characterizing the photon statistics of propagating microwave fields is a fundamental task. We quantify the n^{2}+n photon number variance of thermal microwave photons emitted from a blackbody radiator for mean photon numbers, 0.05≲n≲1.5. We probe the fields using either correlation measurements or a transmon qubit coupled to a microwave resonator. Our experiments provide a precise quantitative characterization of weak microwave states and information on the noise emitted by a Josephson parametric amplifier.

Photon Statistics of Propagating Thermal Microwaves

NASA Astrophysics Data System (ADS)

Goetz, J.; Pogorzalek, S.; Deppe, F.; Fedorov, K. G.; Eder, P.; Fischer, M.; Wulschner, F.; Xie, E.; Marx, A.; Gross, R.

2017-03-01

In experiments with superconducting quantum circuits, characterizing the photon statistics of propagating microwave fields is a fundamental task. We quantify the n2+n photon number variance of thermal microwave photons emitted from a blackbody radiator for mean photon numbers, 0.05 ≲n ≲1.5 . We probe the fields using either correlation measurements or a transmon qubit coupled to a microwave resonator. Our experiments provide a precise quantitative characterization of weak microwave states and information on the noise emitted by a Josephson parametric amplifier.

Development of a microwave clothes dryer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesselring, J.P.; Smith, R.D.

1996-01-01

A laboratory test model of a microwave clothes dryer was constructed and tested over a wide range of test variables, including number of magnetrons and use of auxiliary heat. The tests identified three distinct operating modes: cool drying, which uses only microwave energy and drying occurs at less than 105 F; fast drying, where microwave drying is superimposed on conventional drying; and efficient drying, where the use of microwave energy with waste heat recovery from the power supply results in significant efficiency improvements compared to conventional dryers.

Development of an 83.2 MHz, 3.2 kW solid-state RF amplifier using Wilkinson power divider and combiner for a 10 MeV cyclotron

NASA Astrophysics Data System (ADS)

Song, Ho Seung; Ghergherehchi, Mitra; Oh, Seyoung; Chai, Jong Seo

2017-03-01

We design a stripline-type Wilkinson power divider and combiner for a 3.2 kW solid-state radio frequency (RF) amplifier module and optimize this setup. A Teflon-based printed circuit board is used in the power combiner to transmit high RF power efficiently in the limited space. The reflection coefficient (S11) and insertion loss (S21) related to impedance matching are characterized to determine the optimization process. The resulting two-way divider reflection coefficient and insertion loss were -48.00 dB and -3.22 dB, respectively. The two-way power combiner reflection coefficient and insertion loss were -20 dB and -3.3 dB, respectively. Moreover, the 3.2 kW solid-state RF power test results demonstrate that the proposed power divider and combiner exhibit a maximum efficiency value of 71.3% (combiner loss 5%) at 48 V supply voltage.

A Microwave Thruster for Spacecraft Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiravalle, Vincent P

This presentation describes how a microwave thruster can be used for spacecraft propulsion. A microwave thruster is part of a larger class of electric propulsion devices that have higher specific impulse and lower thrust than conventional chemical rocket engines. Examples of electric propulsion devices are given in this presentation and it is shown how these devices have been used to accomplish two recent space missions. The microwave thruster is then described and it is explained how the thrust and specific impulse of the thruster can be measured. Calculations of the gas temperature and plasma properties in the microwave thruster aremore » discussed. In addition a potential mission for the microwave thruster involving the orbit raising of a space station is explored.« less

Using Microwaves to Heat Lunar Soil

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.

2011-01-01

This slide presentation reviews the use of microwaves to heat lunar soil in order to obtain water. There appears to be large amounts of water in the lunar poles, in Martian areas in lower latitudes and some of the Moons of Jupiter. The presence of water in the south lunar polar region was demonstrated by the Lunar CRater Observation and Sensing Satellite (LCROSS) mission. Microwaves can be used to extract water from lunar soil without excavation. Using microwaves on a lunar soil simulant at least 95% of the water from the regolith permafrost simulant was extracted (2 minutes). The process is modeled using COMSOL Multiphysics Finite Element analysis microwave physics module and demonstrated usingan experiment of an microwave apparatus on a rover.

FEM and Multiphysics Applications at NASA/GSFC

NASA Technical Reports Server (NTRS)

Loughlin, James

2004-01-01

FEM software available to the Mechanical Systems Analysis and Simulation Branch at Goddard Space Flight Center (GSFC) include: 1) MSC/Nastran; 2) Abaqus; 3) Ansys/Multiphysics; 4) COSMOS/M; 5) 'Home-grown' programs; 6) Pre/post processors such as Patran and FEMAP. This viewgraph presentation provides additional information on MSC/Nastran and Ansys/Multiphysics, and includes screen shots of analyzed equipment, including the Wilkinson Microwave Anistropy Probe, a micro-mirror, a MEMS tunable filter, and a micro-shutter array. The presentation also includes information on the verification of results.

Comparison of dark energy models: A perspective from the latest observational data

NASA Astrophysics Data System (ADS)

Li, Miao; Li, Xiaodong; Zhang, Xin

2010-09-01

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation, the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H 0 from the Hubble Space Telescope. Model comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the models. These statistics favor models that give a good fit with fewer parameters. Based on this analysis, we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current data. For other dynamical dark energy models, we find that some of them, such as the α dark energy, constant w, generalized Chaplygin gas, Chevalliear-Polarski-Linder parametrization, and holographic dark energy models, can provide good fits to the current data, and three of them, namely, the Ricci dark energy, agegraphic dark energy, and Dvali-Gabadadze-Porrati models, are clearly disfavored by the data.

Proton-hydrogen collisions for Rydberg n,l-changing transitions in the early Universe

NASA Astrophysics Data System (ADS)

Vrinceanu, Daniel

2013-05-01

Cosmic Microwave Background (CMB) is a vestige radiation generated during the Recombination era, some 390,000 years after the Big Bang, when the Universe had become transparent for the first time. Initial observations of CMB made by the Wilkinson Microwave Anisotropy Probe (WMAP) led to determining the age of the Universe. The mechanisms that drove the recombination have been discovered by using modeling of the primordial plasma and seeking agreement with the observations. The new Plank Surveyor Instrument launched in 2009 is expected to produce data about the recombination era of an unprecedented accuracy, that require including better information regarding the basic atomic physics processes into the present models. In this talk, I will review the results for various Rydberg atom - charge particle collisions and establish their relative importance during the stages of recombination era, with respect to each other and to radiative processes. Energy changing and angular momentum changing collisions with electrons and ions are considered. This work has been supported by NSF through grants to the Institute for Theoretical Atomic and Molecular Physics at Harvard Smithsonian Center for Astrophysics and to the Center for Research on Complex Networks at Texas Southern University.

Use of the Wilkinson catalyst for the ortho-C-H heteroarylation of aromatic amines: facile access to highly extended π-conjugated heteroacenes for organic semiconductors.

PubMed

Huang, Yumin; Wu, Di; Huang, Jingsheng; Guo, Qiang; Li, Juan; You, Jingsong

2014-11-03

An unprecedented catalytic system composed of the Wilkinson catalyst [Rh(PPh3)3Cl] and CF3COOH enabled the highly regioselective cross-coupling of aromatic amines with a variety of heteroarenes through dual C-H bond cleavage. This protocol provided a facile and rapid route from readily available substrates to (2-aminophenyl)heteroaryl compounds, which may be conveniently transformed into highly extended π-conjugated heteroacenes. The experimental studies and calculations showed that thianaphtheno[3,2-b]indoles have large HOMO-LUMO energy gaps and low-lying HOMO levels, and could therefore potentially be high-performance organic semiconductors. Herein we report the first use of a rhodium(I) catalyst for oxidative C-H/C-H coupling reactions. The current innovative catalyst system is much less expensive than [RhCp*Cl2]2/AgSbF6 and could open the door for the application of this approach to other types of C-H activation processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance of a Microwave Bale Moisture Content Meter

USDA-ARS?s Scientific Manuscript database

Measuring the moisture content of cotton bales has been a topic of intense interest in the last few years. A non-contact microwave-based bale moisture meter, Vomax 851-B (Vomax Instrumentation through Samuel Jackson, Lubbock, TX) has been commercially available but independent verification of these...

Cosmological constraints from strong gravitational lensing in clusters of galaxies.

PubMed

Jullo, Eric; Natarajan, Priyamvada; Kneib, Jean-Paul; D'Aloisio, Anson; Limousin, Marceau; Richard, Johan; Schimd, Carlo

2010-08-20

Current efforts in observational cosmology are focused on characterizing the mass-energy content of the universe. We present results from a geometric test based on strong lensing in galaxy clusters. Based on Hubble Space Telescope images and extensive ground-based spectroscopic follow-up of the massive galaxy cluster Abell 1689, we used a parametric model to simultaneously constrain the cluster mass distribution and dark energy equation of state. Combining our cosmological constraints with those from x-ray clusters and the Wilkinson Microwave Anisotropy Probe 5-year data gives Omega(m) = 0.25 +/- 0.05 and w(x) = -0.97 +/- 0.07, which are consistent with results from other methods. Inclusion of our method with all other available techniques brings down the current 2sigma contours on the dark energy equation-of-state parameter w(x) by approximately 30%.

Snow cover of the Upper Colorado River Basin from satellite passive microwave and visual imagery

USGS Publications Warehouse

Josberger, E.G.; Beauvillain, E.

1989-01-01

A comparison of passive microwave images from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and visual images from the Defense Meteorological Satellite Program (DMSP) of the Upper Colorado River Basin shows that passive microwave satellite imagery can be used to determine the extent of the snow cover. Eight cloud-free DMSP images throughout the winter of 1985-1986 show the extent of the snowpack, which, when compared to the corresponding SMMR images, determine the threshold microwave characteristics for snow-covered pixels. With these characteristics, the 27 sequential SMMR images give a unique view of the temporal history of the snow cover extent through the first half of the water year. -from Authors

Non-equilibrium mechanisms of light in the microwave region

NASA Astrophysics Data System (ADS)

Mortenson, Juliana H. J.

2011-09-01

Quantum mechanics and quantum chemistry have taught for more than 100 years that "photons" associated with microwaves cannot exert photochemical effects because their "photon energies" are smaller than chemical bond energies. Those quantum theories have been strongly contradicted within the last few decades by physical experiments demonstrating non-equilibrium, photochemical and photomaterial activity by microwaves. Reactions among scientists to these real physical models and proofs have varied from disbelief and denial, to acceptance of the real physical phenomena and demands for revisions to quantum theory. At the previous "Nature of Light" meeting, an advance in the foundations of quantum mechanics was presented. Those discoveries have revealed the source of these conflicts between quantum theory and microwave experiments. Critical variables and constants were missing from quantum theory due to a minor mathematical inadvertence in Planck's original quantum work. As a result, erroneous concepts were formed nearly a century ago regarding the energetics and mechanisms of lower frequency light, such as in the microwave region. The new discoveries have revealed that the traditional concept of "photons" mistakenly attributed elementary particle status to what is actually an arbitrarily time-based collection of sub-photonic, elementary particles. In a mathematical dimensional sense, those time-based energy measurements cannot be mathematically equivalent to bond energies as historically believed. Only an "isolated quantity of energy", as De Broglie referred to it, can be equivalent to bond energy. With the aid of the new variables and constants, the non-equilibrium mechanisms of light in the microwave region can now be described. They include resonant absorption, splitting frequency stimulation leading to electronic excitation, and resonant acoustic transduction. Numerous practical engineering applications can be envisioned for non-equilibrium microwaves.

Automated Microwave Dielectric Constant Measurement

DTIC Science & Technology

1987-03-01

IJSWC TR 86-46 AD.-A 184 182 AUTOMATED MICROWAVE DIELECTRIC CONSTANT MEASUREMENT SYTIEM BY B. C. GLANCY A. KRALL PESEARCH AND TECHNOLOGY DEPARTMENT...NO0. NO. ACCESSION NO. Silver Spring, Maryland 20903-500061152N ZROO1 ZRO131 R1AA29 11. TITLE (Include Security Classification) AUTOMATED MICROWAVE ...constants as a funct on of microwave frequency has been simplified using an automated testing apparatus. This automated procedure is based on the use of a

Real time data acquisition of a countrywide commercial microwave link network

NASA Astrophysics Data System (ADS)

Chwala, Christian; Keis, Felix; Kunstmann, Harald

2015-04-01

Research in recent years has shown that data from commercial microwave link networks can provide very valuable precipitation information. Since these networks comprise the backbone of the cell phone network, they provide countrywide coverage. However acquiring the necessary data from the network operators is still difficult. Data is usually made available for researchers with a large time delay and often at irregular basis. This of course hinders the exploitation of commercial microwave link data in operational applications like QPE forecasts running at national meteorological services. To overcome this, we have developed a custom software in joint cooperation with our industry partner Ericsson. The software is installed on a dedicated server at Ericsson and is capable of acquiring data from the countrywide microwave link network in Germany. In its current first operational testing phase, data from several hundred microwave links in southern Germany is recorded. All data is instantaneously sent to our server where it is stored and organized in an emerging database. Time resolution for the Ericsson data is one minute. The custom acquisition software, however, is capable of processing higher sampling rates. Additionally we acquire and manage 1 Hz data from four microwave links operated by the skiing resort in Garmisch-Partenkirchen. We will present the concept of the data acquisition and show details of the custom-built software. Additionally we will showcase the accessibility and basic processing of real time microwave link data via our database web frontend.

Ultra-Rapid Crystallization of L-alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization.

PubMed

Lansiquot, Carisse; Boone-Kukoyi, Zainab; Shortt, Raquel; Thompson, Nishone; Ajifa, Hillary; Kioko, Bridgit; Constance, Edward Ned; Clement, Travis; Ozturk, Birol; Aslan, Kadir

2017-01-01

The use of indium tin oxide (ITO) and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine (a model amino acid) is reported. Commercially available ITO dots (< 5 mm) attached to blank poly(methyl)methacrylate (PMMA, 5 cm in diameter with 21-well silicon isolators: referred to as the iCrystal plates) were found to withstand prolonged microwave heating during crystallization experiments. Crystallization of L-alanine was performed at room temperature (a control experiment), with the use of two microwave sources: a 2.45 GHz conventional microwave (900 W, power level 1, a control experiment) and 8 GHz (20 W) solid state, monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity. Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47 ± 2.9 min, 12 ± 7.6 min and 1.5 ± 0.5 min at room temperature, using a conventional microwave and focused monomode microwave heating, respectively. Complete evaporation of the solvent using the focused microwaves was achieved in 3.2 ± 0.5 min, which is ~52-fold and ~172-fold faster than that observed at room temperature and using conventional microwave heating, respectively. The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method: 33 crystals of 585 ± 137 μm in size at room temperature > 37 crystals of 542 ± 100 μm in size with conventional microwave heating > 331 crystals of 311 ± 190 μm in size with focused monomode microwave. FTIR, optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces. In addition, theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.

Ultra-Rapid Crystallization of L-alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization

PubMed Central

Lansiquot, Carisse; Boone-Kukoyi, Zainab; Shortt, Raquel; Thompson, Nishone; Ajifa, Hillary; Kioko, Bridgit; Constance, Edward Ned; Clement, Travis; Ozturk, Birol; Aslan, Kadir

2018-01-01

The use of indium tin oxide (ITO) and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine (a model amino acid) is reported. Commercially available ITO dots (< 5 mm) attached to blank poly(methyl)methacrylate (PMMA, 5 cm in diameter with 21-well silicon isolators: referred to as the iCrystal plates) were found to withstand prolonged microwave heating during crystallization experiments. Crystallization of L-alanine was performed at room temperature (a control experiment), with the use of two microwave sources: a 2.45 GHz conventional microwave (900 W, power level 1, a control experiment) and 8 GHz (20 W) solid state, monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity. Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47 ± 2.9 min, 12 ± 7.6 min and 1.5 ± 0.5 min at room temperature, using a conventional microwave and focused monomode microwave heating, respectively. Complete evaporation of the solvent using the focused microwaves was achieved in 3.2 ± 0.5 min, which is ~52-fold and ~172-fold faster than that observed at room temperature and using conventional microwave heating, respectively. The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method: 33 crystals of 585 ± 137 μm in size at room temperature > 37 crystals of 542 ± 100 μm in size with conventional microwave heating > 331 crystals of 311 ± 190 μm in size with focused monomode microwave. FTIR, optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces. In addition, theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces. PMID:29657884

Spaceborne Microwave Imagers

NASA Technical Reports Server (NTRS)

Stacey, J. M.

1991-01-01

Monograph presents comprehensive overview of science and technology of spaceborne microwave-imaging systems. Microwave images used as versatile orbiting, remote-sensing systems to investigate atmospheres and surfaces of planets. Detect surface objects through canopies of clouds, measure distributions of raindrops in clouds that their views penetrate, find meandering rivers in rain forests and underground water in arid regions, and provide information on ocean currents, wakes, ice/water boundaries, aircraft, ships, buoys, and bridges.

Adhesive bonding using variable frequency microwave energy

DOEpatents

Lauf, Robert J.; McMillan, April D.; Paulauskas, Felix L.; Fathi, Zakaryae; Wei, Jianghua

1998-01-01

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

Adhesive bonding using variable frequency microwave energy

DOEpatents

Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

1998-08-25

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

Adhesive bonding using variable frequency microwave energy

DOEpatents

Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

1998-09-08

Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

Microwave thermal radiation effects on skin tissues

NASA Astrophysics Data System (ADS)

Yoon, Hargsoon; Song, Kyo D.; Lee, Uhn; Choi, Sang H.

2012-10-01

Microwave/RF energy has been used for wireless power transmission including many therapeutic applications, such as transurethral microwave therapy (TUMT). For safe uses of RF power, it is important to know how to deliver microwave energy on focused area and control the temperature changes not to drastically increase on adjacent areas. Graphical analysis of thermal loading factor is important to understand how to achieve effective transmission of microwave through the tissue. The loss mechanism while transmission often appears as thermal effects due to absorption of microwave, especially for materials such as human skin, muscles, and other organic parts including brain. In this paper, microwave thermal effects are investigated to measure temperatures, penetration depth through animal skins in terms of input power and various frequencies. This result will be compare with the case of human applications.

High-Sensitivity Microwave Optics.

ERIC Educational Resources Information Center

Nunn, W. M., Jr.

1981-01-01

Describes a 3.33-cm wavelength (9 GHz) microwave system that achieves a high overall signal sensitivity and a well-collimated beam with moderate-size equipment. The system has been used to develop microwave versions of the Michelson interferometer, Bragg reflector, Brewster's law and total internal reflection, and Young's interference experiment.…

Utilizing commercial microwave for rapid and effective immunostaining.

PubMed

Owens, Katrina; Park, Ji H; Kristian, Tibor

2013-09-30

There is an accumulating literature demonstrating the application of microwaves across a wide spectrum of histological techniques. Although exposure to microwaves for short periods resulted in substantial acceleration of all procedures this technique still is not adopted widely. In part, this may be due to concerns over solutions that will avoid induction of thermal damage to the tissue when using standard microwave. Here, we offer a cooling setup that can be used with conventional microwave ovens. We utilized dry ice for effective cooling during microwave irradiation of tissue samples. To prevent overheating, the cups with tissue during exposure to microwaves were surrounded with powdered dry ice. Since the dry ice does not touch the walls of the cups, freezing is prevented. Overheating is avoided by alternating the microwave treatment with 1-2 min time periods when the cups are cooled outside of the microwave oven. This technique was used on mouse brain sections that were immunostained with microglia-specific CD68 antiserum and astrocyte labeling GFAP antibody. Both standard and microwave-assisted immonolabeling gave comparable results visualizing cells with fine processes and low background signal. Short incubation time in the microwave requires high concentrations of antibody for tissue immunostaining. We show that by prolonging the microwaving procedure we were able to reduce the antibody concentration to the levels used in standard immunostaining protocol. In summary, our technique gives a possibility to use a conventional microwave for rapid and effective immunolabeling resulting in reduced amount of antibody required for satisfactory immunostaining. Published by Elsevier B.V.

Megahertz-resolution programmable microwave shaper.

PubMed

Li, Jilong; Dai, Yitang; Yin, Feifei; Li, Wei; Li, Ming; Chen, Hongwei; Xu, Kun

2018-04-15

A novel microwave shaper is proposed and demonstrated, of which the microwave spectral transfer function could be fully programmable with high resolution. We achieve this by bandwidth-compressed mapping a programmable optical wave-shaper, which has a lower frequency resolution of tens of gigahertz, to a microwave one with resolution of tens of megahertz. This is based on a novel technology of "bandwidth scaling," which employs bandwidth-stretched electronic-to-optical conversion and bandwidth-compressed optical-to-electronic conversion. We demonstrate the high resolution and full reconfigurability experimentally. Furthermore, we show the group delay variation could be greatly enlarged after mapping; this is then verified by the experiment with an enlargement of 194 times. The resolution improvement and group delay magnification significantly distinguish our proposal from previous optics-to-microwave spectrum mapping.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, C.E.; Morrow, M.S.

1993-10-12

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, Cressie E.; Morrow, Marvin S.

1993-01-01

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Detection of chemical contraband using spectroscopic microwave imaging

NASA Astrophysics Data System (ADS)

Falconer, David G.; Watters, David G.

1994-02-01

We have developed and demonstrated a microwave technique for detecting high explosives, illegal drugs, and other chemical contraband in checked airline baggage. Our technique isolates suspicious materials using microwave tomography and identifies chemical contraband using microwave spectroscopy. Measurements in the frequency range 2 - 18 GHz indicate that microwave energy will penetrate nonmetallic suitcases and that contraband materials feature distinct dielectric spectra at these wavelengths. We have also formed microwave images of a soft-sided suitcase and its contents. After manually segmenting the microwave imagery, we successfully identified chemical simulants for both high explosives and illegal drugs.

Microwave switching power divider. [antenna feeds

NASA Technical Reports Server (NTRS)

Stockton, R. J.; Johnson, R. W. (Inventor)

1981-01-01

A pair of parallel, spaced-apart circular ground planes define a microwave cavity with multi-port microwave power distributing switching circuitry formed on opposite sides of a thin circular dielectric substrate disposed between the ground planes. The power distributing circuitry includes a conductive disk located at the center of the substrate and connected to a source of microwave energy. A high speed, low insertion loss switching diode and a dc blocking capacitor are connected in series between the outer end of a transmission line and an output port. A high impedance, microwave blocking dc bias choke is connected between each switching diode and a source of switching current. The switching source forward biases the diodes to couple microwave energy from the conductive disk to selected output ports and, to associated antenna elements connected to the output ports to form a synthesized antenna pattern.

Computer-Generated Microwave Holograms.

ERIC Educational Resources Information Center

Leming, Charles W.; Hastings, Orestes Patterson, III

1980-01-01

Described is the phasor method of superposition of waves. The intensity pattern from a system of microwave sources is calculated point by point on a plane corresponding to a film emulsion, and then printed and directly converted to a hologram for 3-cm microwaves. Calculations, construction, and viewing of holograms are included. (Author/DS)

Microwave Transversal Equalizer.

DTIC Science & Technology

1980-05-01

AD-AO?7 603 EATONCORP MELVILLE NY AIL DIV F/6 9/5 MICROWAVE TRANSVERSAL EQUALIZER .(U) MAY 80 J WOLCZOK. 6 KANISCHAK F 3 0602-T8-C-0352 UNCLASSIFIED... Equalizer (MTE) Side-lobe distortion Equalization II Automation ABSTRACT (Continue on revere side It necesary and identify by block numb.r) A...Microwave Transversal Equalizer has been designed, fabricated, and installed at RADC and is capable of reducing side-lobe distortion levels of -18 dBm to

Phenomenology of microwave coupling. Part I

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, R.J.; Breakall, J.K.; Hudson, H.G.

Recent advances in the development of high power microwave sources have increased the potential for future deployment of microwave weapons. A key ingredient in being able to predict the vulnerability of military systems to such threats involves understanding the phenomenology of how electromagnetic energy couples into cavity-like objects, or the so-called back-door coupling. A similar but much longer standing problem is that of nuclear electromagnetic pulses (EMP) in which the frequencies extend up to several hundreds of MHz. However, compared to EMP coupling, microwave coupling (from 1 GHz to above 40 GHz) is distinctively different because the wavelength is comparablemore » to the size of the ports of entry (apertures, seams, cracks, protruding connectors, etc.). These ports of entry and the interior configuration of a vulnerable system are no longer below cutoff, and can permit significant penetration of the microwave energy into susceptible electronic systems. In fact, these coupling paths can be highly resonant at certain microwave frequencies, making the shielding against microwave threats difficult. This report summarizes the initial efforts at Lawrence Livermore National Laboratory to study the phenomenology of back door coupling at the low microwave frequencies (up to 2.5 GHz). These studies were limited to 2.5 GHz because the limitations of the Electromagnetic Transient Range Facility.« less

MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS

EPA Science Inventory

Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

Free-space microwave power transmission study, phase 3

NASA Technical Reports Server (NTRS)

Brown, W. C.

1975-01-01

The results of an investigation of the technology of free-space power transmission by microwave beam are presented. A description of the steps that were taken to increase the overall dc to dc efficiency of microwave power transmission from 15 percent to over 50 percent is given. Included in this overall efficiency were the efficiencies of the dc to microwave conversion, the microwave transmission itself, and the microwave to dc conversion. Improvements in launching the microwave beam with high efficiency by means of a dual mode horn resulted in 95 percent of the output of the microwave generator reaching the receiving area. Emphasis was placed upon successive improvements in reception and rectification of the microwave power, resulting in the design of a rectenna device for this purpose whose efficiency was 75 percent. The procedures and the hardware developed were the basis for tests certified by the Jet Propulsion Laboratory in which an overall dc to dc efficiency of 54 percent was achieved.

Tandem microwave waste remediation and decontamination system

DOEpatents

Wicks, George G.; Clark, David E.; Schulz, Rebecca L.

1999-01-01

The invention discloses a tandem microwave system consisting of a primary chamber in which microwave energy is used for the controlled combustion of materials. A second chamber is used to further treat the off-gases from the primary chamber by passage through a susceptor matrix subjected to additional microwave energy. The direct microwave radiation and elevated temperatures provide for significant reductions in the qualitative and quantitative emissions of the treated off gases. The tandem microwave system can be utilized for disinfecting wastes, sterilizing materials, and/or modifying the form of wastes to solidify organic or inorganic materials. The simple design allows on-site treatment of waste by small volume waste generators.

Microwave off-gas treatment apparatus and process

DOEpatents

Schulz, Rebecca L.; Clark, David E.; Wicks, George G.

2003-01-01

The invention discloses a microwave off-gas system in which microwave energy is used to treat gaseous waste. A treatment chamber is used to remediate off-gases from an emission source by passing the off-gases through a susceptor matrix, the matrix being exposed to microwave radiation. The microwave radiation and elevated temperatures within the combustion chamber provide for significant reductions in the qualitative and quantitative emissions of the gas waste stream.

Investigation of dielectric properties of different cake formulations during microwave and infrared-microwave combination baking.

PubMed

Sakiyan, Ozge; Sumnu, Gulum; Sahin, Serpil; Meda, Venkatesh

2007-05-01

Dielectric properties can be used to understand the behavior of food materials during microwave processing. Dielectric properties influence the level of interaction between food and high frequency electromagnetic energy. Dielectric properties are, therefore, important in the design of foods intended for microwave preparation. In this study, it was aimed to determine the variation of dielectric properties of different cake formulations during baking in microwave and infrared-microwave combination oven. In addition, the effects of formulation and temperature on dielectric properties of cake batter were examined. Dielectric constant and loss factor of cake samples were shown to be dependent on formulation, baking time, and temperature. The increase in baking time and temperature decreased dielectric constant and loss factor of all formulations. Fat content was shown to increase dielectric constant and loss factor of cakes.

Microwave-Assisted Rapid Enzymatic Synthesis of Nucleic Acids.

PubMed

Hari Das, Rakha; Ahirwar, Rajesh; Kumar, Saroj; Nahar, Pradip

2016-07-02

Herein we report microwave-induced enhancement of the reactions catalyzed by Escherichia coli DNA polymerase I and avian myeloblastosis virus-reverse transcriptase. The reactions induced by microwaves result in a highly selective synthesis of nucleic acids in 10-50 seconds. In contrast, same reactions failed to give desired reaction products when carried out in the same time periods, but without microwave irradiation. Each of the reactions was carried out for different duration of microwave exposure time to find the optimum reaction time. The products produced by the respective enzyme upon microwave irradiation of the reaction mixtures were identical to that produced by the conventional procedures. As the microwave-assisted reactions are rapid, microwave could be a useful alternative to the conventional and time consuming procedures of enzymatic synthesis of nucleic acids.

A Microwave Interferometer on an Air Track.

ERIC Educational Resources Information Center

Polley, J. Patrick

1993-01-01

Uses an air track and microwave transmitters and receivers to make a Michelson interferometer. Includes three experiments: (1) measuring the wavelength of microwaves, (2) measuring the wavelength of microwaves by using the Doppler Effect, and (3) measuring the Doppler shift. (MVL)

78 FR 6217 - Facilitating the Use of Microwave for Wireless Backhaul and Other Uses and Providing Additional...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-30

... Broadcast Auxiliary Service and Operational Fixed Microwave Licensees AGENCY: Federal Communications... announces that the Office of Management and Budget (OMB) has approved, for a period of three years, the... Service and Operational Fixed Microwave Licensees. This notice is consistent with the Order, which stated...

78 FR 7278 - Facilitating the use of Microwave for Wireless Backhaul and Other Uses and Providing Additional...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-01

... Broadcast Auxiliary Service and Operational Fixed Microwave Licensees AGENCY: Federal Communications... announces that the Office of Management and Budget (OMB) has approved, for a period of three years, the... Broadcast Auxiliary Service and Operational Fixed Microwave Licensees. This notice is consistent with the R...

Microwave remote sensing: Active and passive. Volume 1 - Microwave remote sensing fundamentals and radiometry

NASA Technical Reports Server (NTRS)

Ulaby, F. T.; Moore, R. K.; Fung, A. K.

1981-01-01

The three components of microwave remote sensing (sensor-scene interaction, sensor design, and measurement techniques), and the applications to geoscience are examined. The history of active and passive microwave sensing is reviewed, along with fundamental principles of electromagnetic wave propagation, antennas, and microwave interaction with atmospheric constituents. Radiometric concepts are reviewed, particularly for measurement problems for atmospheric and terrestrial sources of natural radiation. Particular attention is given to the emission by atmospheric gases, clouds, and rain as described by the radiative transfer function. Finally, the operation and performance characteristics of radiometer receivers are discussed, particularly for measurement precision, calibration techniques, and imaging considerations.

Microwave Hydrothermal Synthesis of Reduced Graphene Oxide: Effects of Microwave Power and Irradiation Time

NASA Astrophysics Data System (ADS)

Agusu, La; Ode Ahmad, La; Anggara, Desna; Alimin; Mitsudo, Seitaro; Fujii, Yutaka; Kikuchi, Hiromitsu

2018-04-01

Reduced graphene oxide has been synthesihzed by one-pot microwave assisted hydrothermal method. Effects of microwave power and irradiation time to its crystal structure and electrical conductivity were investigated. Here, graphene oxide, firstly, were synthesized by modified hummers method and subsequently mixed with Zn as a reducing agent. Then it was transferred to modified domestic microwave oven (800 watts) with glass distiller equipment for completely reduction process. Three different power levels (240, 400, 630 watts) and two cases of irradiation times (20 and 40 minutes) were treated. XRD study shows that irradiation time variation is more effective than the variation of power level. Power level of 270 watts and for 40 minutes microwave irradiation are enough for producing estimated bilayer rGO with graphene interlayer of ~0.4 nm. Bilayer graphene and water molecule (~0.3 nm) may vibrate the same manner and perhaps they are accepting the same temperature. Graphene seems to be re-arranged in unspecified way among the thermal pressure, temperature gradient and/or water surface tension between graphene and water induced by microwave, in order to achieve thermal equilibrium through out the system The electrical conductivity rGO/PVA (60/40 %w) paper are ranging from 15.6 to 43.4 mS/cm.

Microwave radiometer studies of atmospheric water over the oceans, volume 2

NASA Technical Reports Server (NTRS)

Katsaros, Kristina B.

1992-01-01

Since the Seasat carried the Scanning Multichannel Microwave Radiometer (SMMR) into space in July of 1978, shortly followed by the SMMR on Nimbus 7, which operated for almost a decade, a new type of data source on atmospheric water vapor and other meteorological parameters has been available for analysis of weather systems over the ocean. Since 1987, we have had the Scanning Multichannel Microwave/Imager (SSM/I) instrument on Defense Meteorological Satellites providing similar data. We present a collection of our work performed over the last years of the study.

Microwaving of normally opaque and semi-opaque substances

DOEpatents

Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

1990-01-01

Method of heating small particles using microwave radiation which are not normally capable of being heated by microwaves. The surfaces of the particles are coated with a material which is transparent to microwave radiation in order to cause microwave coupling to the particles and thus accomplish heating of the particles.

Transverse Mode Electron Beam Microwave Generator

NASA Technical Reports Server (NTRS)

Wharton, Lawrence E.

1994-01-01

An electron beam microwave device having an evacuated interaction chamber to which are coupled a resonant cavity which has an opening between the resonant cavity and the evacuated interaction chamber and an electron gun which causes a narrow beam of electrons to traverse the evacuated interaction chamber. The device also contains a mechanism for feeding back a microwave electromagnetic field from the resonant cavity to the evacuated interaction chamber in such a way as to modulate the direction of propagation of the electron beam, thereby further amplifyjng the microwave electromagnetic field. Furthermore, provision is made for coupling the electromagnetic field out of the electron beam microwave device.

Effects of Pulsed 2.856 GHz Microwave Exposure on BM-MSCs Isolated from C57BL/6 Mice

PubMed Central

Wang, Changzhen; Wang, Xiaoyan; Zhou, Hongmei; Dong, Guofu; Guan, Xue; Wang, Lifeng; Xu, Xinping; Wang, Shuiming; Chen, Peng; Peng, Ruiyun; Hu, Xiangjun

2015-01-01

The increasing use of microwave devices over recent years has meant the bioeffects of microwave exposure have been widely investigated and reported. However the exact biological fate of bone marrow MSCs (BM-MSCs) after microwave radiation remains unknown. In this study, the potential cytotoxicity on MSC proliferation, apoptosis, cell cycle, and in vitro differentiation were assayed following 2.856 GHz microwave exposure at a specific absorption rate (SAR) of 4 W/kg. Importantly, our findings indicated no significant changes in cell viability, cell division and apoptosis after microwave treatment. Furthermore, we detected no significant effects on the differentiation ability of these cells in vitro, with the exception of reduction in mRNA expression levels of osteopontin (OPN) and osteocalcin (OCN). These findings suggest that microwave treatment at a SAR of 4 W/kg has undefined adverse effects on BM-MSCs. However, the reduced-expression of proteins related to osteogenic differentiation suggests that microwave can the influence at the mRNA expression genetic level. PMID:25658708

Microwave SQUID Multiplexer Demonstration for Cosmic Microwave Background Imagers.

PubMed

Dober, B; Becker, D T; Bennett, D A; Bryan, S A; Duff, S M; Gard, J D; Hays-Wehle, J P; Hilton, G C; Hubmayr, J; Mates, J A B; Reintsema, C D; Vale, L R; Ullom, J N

2017-12-01

Key performance characteristics are demonstrated for the microwave SQUID multiplexer (µmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the µmux produces a white, input referred current noise level of [Formula: see text] at -77 dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure [Formula: see text] in the TES-coupled channels biased at 65% of the sensor normal resistance. This noise level is consistent with that predicted from bolometer thermal fluctuation (i.e. phonon) noise. Furthermore, the power spectral density is white over a range of frequencies down to ~ 100 mHz, which enables CMB mapping on large angular scales that constrain the physics of inflation. Additionally, we report cross-talk measurements that indicate a level below 0.3%, which is less than the level of cross-talk from multiplexed readout systems in deployed CMB imagers. These measurements demonstrate the µmux as a viable readout technique for future CMB imaging instruments.

Microwave heat treating of manufactured components

DOEpatents

Ripley, Edward B.

2007-01-09

An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

Microwave Tissue Ablation: Biophysics, Technology and Applications

PubMed Central

2010-01-01

Microwave ablation is an emerging treatment option for many cancers, cardiac arrhythmias and other medical conditions. During treatment, microwaves are applied directly to tissues to produce rapid temperature elevations sufficient to produce immediate coagulative necrosis. The engineering design criteria for each application differ, with individual consideration for factors such as desired ablation zone size, treatment duration, and procedural invasiveness. Recent technological developments in applicator cooling, power control and system optimization for specific applications promise to increase the utilization of microwave ablation in the future. This article will review the basic biophysics of microwave tissue heating, provide an overview of the design and operation of current equipment, and outline areas for future research for microwave ablation. PMID:21175404

CHEMICAL SYNTHESIS & TRANSFORMATIONS USING MICROWAVES

EPA Science Inventory

A historical account of the utility of microwaves in a variety of chemical synthesis applications will be presented, including a solvent-free strategy that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of recyclable mineral supports such...

Soliton Microwave Generator

NASA Astrophysics Data System (ADS)

Degrassie, J. S.

1990-12-01

The Soliton Microwave Generator (SMG) represents a truly new concept in the field of high power microwave (HPM) generation. A nonlinear, dispersive transmission line is used to convert an input voltage pulse into an HPM burst at the output. The system is all solid state and projects to be efficient and reliable. Single module peak powers in excess of 1 GW appear feasible, while combining modular units leads to a 10 GW system projection. This project for the DOE has allowed the first steps necessary in experimentally demonstrating the SMG. The project has ended successfully. A relatively high power lumped circuit SMG operating in the uhf band was designed, fabricated, and tested. The maximum peak output RF power was 16 MW from this line approx. 90 cm in length and 2 sq cm in cross section with a peak power efficiency of roughly 20 percent. Additionally a low power continuous strip-line approach demonstrated microwave generation well into L band, at approx. 2 GHz.

Orthodontic instrument sterilization with microwave irradiation.

PubMed

Yezdani, Arif; Mahalakshmi, Krishnan; Padmavathy, Kesavaram

2015-04-01

This study was designed to evaluate the efficiency of microwave sterilization of orthodontic instruments and molar bands immersed in plain distilled water with and without oral rinse, and to ascertain the minimum time of exposure required to sterilize. The orthodontic instruments (hinged and nonhinged), molar bands and mouth mirrorsused in the patient 's mouth were selected for the study. The instruments were divided into two groups - Group I with oral rinse-set A (0.01% chlorhexidine gluconate) and set B (0.025% betadine) and Group II (included sets C and D without oral rinse). The instruments of set A, B and C were microwaved at 2,450 MHz, 800 W for 5 min, whereas, set D was microwaved for 10 min at the same above mentioned specifications. The efficacy of sterilization was assessed by stab inoculation of the instruments onto trypticase soya agar plates. The plates were checked for bacterial growth following incubation at 37 °C for 24 h. For sterility control,Geobacillus stearothermophilus (MTCC 1518) was included. No growth was observed in the plates that were inoculated with the microwaved orthodontic instruments of sets A, B and D, whereas scanty bacterial growth was observed in the plates inoculatedwith the microwaved set C instruments. Effective sterilization was achieved when the orthodontic instruments and molar bands were immersed in distilled water without oral rinse and microwaved for 10 min as also for those that were immersed in distilled water with oral rinse and microwaved for 5 min.

Ignition methods and apparatus using microwave energy

DOEpatents

DeFreitas, Dennis Michael; Migliori, Albert

1997-01-01

An ignition apparatus for a combustor includes a microwave energy source that emits microwave energy into the combustor at a frequency within a resonant response of the combustor, the combustor functioning as a resonant cavity for the microwave energy so that a plasma is produced that ignites a combustible mixture therein. The plasma preferably is a non-contact plasma produced in free space within the resonant cavity spaced away from with the cavity wall structure and spaced from the microwave emitter.

The cosmic microwave background

NASA Technical Reports Server (NTRS)

Silk, Joseph

1991-01-01

Recent limits on spectral distortions and angular anisotropies in the cosmic microwave background are reviewed. The various backgrounds are described, and the theoretical implications are assessed. Constraints on inflationary cosmology dominated by cold dark matter (CDM) and on open cosmological models dominated by baryonic dark matter (BDM), with, respectively, primordial random phase scale-invariant curvature fluctuations or non-gaussian isocurvature fluctuations are described. More exotic theories are addressed, and I conclude with the 'bottom line': what theorists expect experimentalists to be measuring within the next two to three years without having to abandon their most cherished theories.

Report from the Passive Microwave Data Set Management Workshop

NASA Technical Reports Server (NTRS)

Armstrong, Ed; Conover, Helen; Goodman, Michael; Krupp, Brian; Liu, Zhong; Moses, John; Ramapriyan, H. K.; Scott, Donna; Smith, Deborah; Weaver, Ronald

2011-01-01

Passive microwave data sets are some of the most important data sets in the Earth Observing System Data and Information System (EOSDIS), providing data as far back as the early 1970s. The widespread use of passive microwave (PM) radiometer data has led to their collection and distribution over the years at several different Earth science data centers. The user community is often confused by this proliferation and the uneven spread of information about the data sets. In response to this situation, a Passive Microwave Data Set Management Workshop was held 17 ]19 May 2011 at the Global Hydrology Resource Center, sponsored by the NASA Earth Science Data and Information System (ESDIS) Project. The workshop attendees reviewed all primary (Level 1 ]3) PM data sets from NASA and non ]NASA sensors held by NASA Distributed Active Archive Centers (DAACs), as well as high ]value data sets from other NASA ]funded organizations. This report provides the key findings and recommendations from the workshop as well as detailed tabluations of the datasets considered.

GREENER SYNTHETIC TRANSFORMATIONS USING MICROWAVES

EPA Science Inventory

Microwave irradiation has been used for a variety of organic transformations wherein chemical reactions are expedited because of selective adsorption of microwave (MW) energy by polar molecules, non-polar molecules being inert to the MW dielectric loss. The MW application under s...

Microwave Sterilization in School Microbiology.

ERIC Educational Resources Information Center

Wynn, Brian; Dixon, Angela

1988-01-01

Described are two investigations carried out in a high school biology department using a domestic microwave oven to compare the relative attributes of the autoclave and microwave oven in school use. Discussed are equipment, methods, and results of each investigation. (Author/CW)

Harmonic distortion in microwave photonic filters.

PubMed

Rius, Manuel; Mora, José; Bolea, Mario; Capmany, José

2012-04-09

We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index commonly used to neglect high-order terms, we have analyzed the harmonic distortion involved in microwave photonic structures with periodic and non-periodic frequency responses. We show that it is possible to design microwave photonic filters with reduced harmonic distortion and high linearity even under large signal operation.

Satellite microwave observations of soil moisture variations. [by the microwave radiometer on the Nimbus 5 satellite

NASA Technical Reports Server (NTRS)

Schmugge, T. J.; Rango, A.; Neff, R.

1975-01-01

The electrically scanning microwave radiometer (ESMR) on the Nimbus 5 satellite was used to observe microwave emissions from vegetated and soil surfaces over an Illinois-Indiana study area, the Mississippi Valley, and the Great Salt Lake Desert in Utah. Analysis of microwave brightness temperatures (T sub B) and antecedent rainfall over these areas provided a way to monitor variations of near-surface soil moisture. Because vegetation absorbs microwave emission from the soil at the 1.55 cm wavelength of ESMR, relative soil moisture measurements can only be obtained over bare or sparsely vegetated soil. In general T sub B increased during rainfree periods as evaporation of water and drying of the surface soil occurs, and drops in T sub B are experienced after significant rainfall events wet the soil. Microwave observations from space are limited to coarse resolutions (10-25 km), but it may be possible in regions with sparse vegetation cover to estimate soil moisture conditions on a watershed or agricultural district basis, particularly since daily observations can be obtained.

Master Equation Analysis of Thermal and Nonthermal Microwave Effects.

PubMed

Ma, Jianyi

2016-10-11

Master equation is a successful model to describe the conventional heating reaction, it is expanded to capture the "microwave effect" in this work. The work equation of "microwave effect" included master equation presents the direct heating, indirect heating, and nonthermal effect about the microwave field. The modified master equation provides a clear physics picture to the nonthermal microwave effect: (1) The absorption and the emission of the microwave, which is dominated by the transition dipole moment between two corresponding states and the intensity of the microwave field, provides a new path to change the reaction rate constants. (2) In the strong microwave field, the distribution of internal states of the molecules will deviate from the equilibrium distribution, and the system temperature defined in the conventional heating reaction is no longer available. According to the general form of "microwave effect" included master equation, a two states model for unimolecular dissociation is proposed and is used to discuss the microwave nonthermal effect particularly. The average rate constants can be increased up to 2400 times for some given cases without the temperature changed in the two states model. Additionally, the simulation of a model system was executed using our State Specified Master Equation package. Three important conclusions can be obtained in present work: (1) A reasonable definition of the nonthermal microwave effect is given in the work equation of "microwave effect" included master equation. (2) Nonthermal microwave effect possibly exists theoretically. (3) The reaction rate constants perhaps can be changed obviously by the microwave field for the non-RRKM and the mode-specified reactions.

Enhanced Microwave Hyperthermia of Cancer Cells with Fullerene.

PubMed

Sun, Mingrui; Kiourti, Asimina; Wang, Hai; Zhao, Shuting; Zhao, Gang; Lu, Xiongbin; Volakis, John L; He, Xiaoming

2016-07-05

Hyperthermia generated with various energy sources including microwave has been widely studied for cancer treatment. However, the potential damage due to nontargeted heating of normal tissue is a major hurdle to its widespread application. Fullerene is a potential agent for improving cancer therapy with microwave hyperthermia but is limited by its poor solubility in water for biomedical applications. Here we report a combination therapy for enhanced cancer cell destruction by combining microwave heating with C60-PCNPs consisting of fullerene (C60) encapsulated in Pluronic F127-chitosan nanoparticles (PCNPs) with high water solubility. A cell culture dish integrated with an antenna was fabricated to generate microwave (2.7 GHz) for heating PC-3 human prostate cancer cells either with or without the C60-PCNPs. The cell viability data show that the C60-PCNPs alone have minimal cytotoxicity. The combination of microwave heating and C60-PCNPs is significantly more effective than the microwave heating alone in killing the cancer cells (7.5 versus 42.2% cell survival). Moreover, the combination of microwave heating and C60-PCNPs is significantly more destructive to the cancer cells than the combination of simple water-bath heating (with a similar thermal history to microwave heating) and C60-PCNPs (7.5 versus 32.5% survival) because the C60 in the many nanoparticles taken up by the cells can absorb the microwave energy and convert it into heat to enhance heating inside the cells under microwave irradiation. These data suggest the great potential of targeted heating via fullerene for enhanced cancer treatment by microwave hyperthermia.

Microwave Processing of Planetary Surfaces for the Extraction of Volatiles

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William

2011-01-01

In-Situ Resource Utilization will be necessary for sustained exploration of space. Volatiles are present in planetary soils, but water by far has the most potential for effective utilization. The presence of water at the lunar poles, Mars, and possibly on Phobos opens the possibility of producing LOX for propellant. Water is also a useful radiation shielding material , and valuable to replenish expendables (water and oxygen) required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating soil effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on soil dielectric properties. Methods for complex electric permittivity and magnetic permeability measurement are being developed and used for measurements of lunar soil simulants. A new method for delivery of microwaves deep into a planetary surface is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. We are planning to set up a planetary testbed in a large vacuum chamber in the coming year. Recent results are discussed.

Efficacy and survival analysis of percutaneous radiofrequency versus microwave ablation for hepatocellular carcinoma: an Egyptian multidisciplinary clinic experience.

PubMed

Abdelaziz, Ashraf; Elbaz, Tamer; Shousha, Hend Ibrahim; Mahmoud, Sherif; Ibrahim, Mostafa; Abdelmaksoud, Ahmed; Nabeel, Mohamed

2014-12-01

Hepatocellular carcinoma (HCC) is a primary tumor of the liver with poor prognosis. For early stage HCC, treatment options include surgical resection, liver transplantation, and percutaneous ablation. Percutaneous ablative techniques (radiofrequency and microwave techniques) emerged as best therapeutic options for nonsurgical patients. We aimed to determine the safety and efficacy of radiofrequency and microwave procedures for ablation of early stage HCC lesions and prospectively follow up our patients for survival analysis. One Hundred and 11 patients with early HCC are managed in our multidisciplinary clinic using either radiofrequency or microwave ablation. Patients are assessed for efficacy and safety. Complete ablation rate, local recurrence, and overall survival analysis are compared between both procedures. Radiofrequency ablation group (n = 45) and microwave ablation group (n = 66) were nearly comparable as regards the tumor and patients characteristics. Complete ablation was achieved in 94.2 and 96.1% of patients managed by radiofrequency and microwave ablation techniques, respectively (p value 0.6) with a low rate of minor complications (11.1 and 3.2, respectively) including subcapsular hematoma, thigh burn, abdominal wall skin burn, and pleural effusion. Ablation rates did not differ between ablated lesions ≤ 3 and 3-5 cm. A lower incidence of local recurrence was observed in microwave group (3.9 vs. 13.5% in radiofrequency group, p value 0.04). No difference between both groups as regards de novo lesions, portal vein thrombosis, and abdominal lymphadenopathy. The overall actuarial probability of survival was 91.6% at 1 year and 86.1% at 2 years with a higher survival rates noticed in microwave group but still without significant difference (p value 0.49). Radiofrequency and microwave ablations led to safe and equivalent ablation and survival rates (with superiority for microwave ablation as regards the incidence of local recurrence).

Microwave-assisted generation of standard gas mixtures.

PubMed

Xiong, Guohua; Pawliszyn, Janusz

2002-05-15

Microwave heating was employed for preparation of the standard gas of volatile organic compounds (VOCs) and semivolatile organic compounds (semi-VOCs) by using a 1000 W commercial domestic microwave oven and 1 L gas-sampling bulbs. The VOCs investigated were benzene, chloroform, 1,3-dichlorobenzene, tetrachloroethylene, toluene, and 1,1,2-trichloroethane, and the semi-VOCs used were the polychlorinated biphenyls (PCBs) PCB 1016 and PCB 1248. Since these weakly or nonpolar molecules are very poor absorbers of microwave energy, an appropriate amount of water was introduced to accept microwave radiation and act as the thermal source to accelerate their evaporation. The glass bulb may also contribute thermal energy to the VOCs/semi-VOCs by accepting microwave energy to a small degree. For 0.5 microL of liquid VOCs on 10 mg of glass wool, it was shown that 15 microL of H2O and 60 s of microwave heating yielded a very efficient evaporation [97.2-106.4%, compared with a classic method (Muller, L; Gorecki, T.; Pawliszyn, J. Fresenius' J. Anal. Chem. 1999, 364, 610-616)]. For 1 microL of PCB solution (1000 microg/mL in hexane), 15 microL of H2O and 90 s of microwave heating also provided a complete evaporation. The addition of water was particularly significant for microwave-assisted evaporation of PCBs because semi-VOCs are much more difficult to evaporate than VOCs. This developed microwave technique proved to be quite simple, powerful, rapid, accurate, and safe for the preparation of VOC/semi-VOC standard gas. Solid- phase microextraction combined with gas chromatography was used for the gas analysis.

An Orbital "Virtual Radar" from TRMM Passive Microwave and Lightning Observations

NASA Technical Reports Server (NTRS)

Boccippio, Dennis J.

2004-01-01

The retrieval of vertical structure from joint passive microwave and lightning observations is demonstrated. Three years of data from the TRMM (Tropical Rainfall Measuring Mission) are used as a training dataset for regression and classification neural networks; the TMI (TRMM Microwave Imager) and LIS (Lightning Imaging Sensor) provide the inputs, the PR (Precipitation Radar) provides the training targets. Both vertical reflectivity profile categorization (into 9 convective, 7 stratiform, 2 mixed and 6 anvil types) and geophysical parameters (surface rainfall, vertically integrated liquid (VIL), ice water content (IWC) and echo tops) are retrieved. Retrievals are successful over both land and ocean surfaces. The benefit of using lightning observations as inputs to these retrievals is quantitatively demonstrated; lightning essentially provides an additional convective/stratiform discriminator, and is most important for isolation of midlevel (tops in the mixed phase region) convective profile types (this is because high frequency passive microwave observations already provide good convective/stratiform discrimination for deep convective profiles). This is highly relevant as midlevel convective profiles account for an extremely large fraction of tropical rainfall, and yet are most difficult to discriminate from comparable-depth stratiform profile types using passive microwave observations alone.

Microwave heating apparatus and method

DOEpatents

Johnson, Andrew J.; Petersen, Robert D.; Swanson, Stephen D.

1990-01-01

An apparatus is provided for heating and melting materials using microwave energy, and for permitting them to solidify. The apparatus includes a microwave energy source, a resonant cavity having an opening in its floor, a microwave energy choke encompassing the opening in the floor of the cavity, a metal container to hold the materials to be heated and melted, a turntable, and a lift-table. During operation, the combined action of the turntable and the lift-table position the metal container so that the top of the container is level with the floor of the cavity, is in substantial registration with the floor opening, and is encompassed by the microwave energy choke; thus, during operation, the interior of the container defines part of the resonant cavity. Additionally, a screw feeder, extending into the cavity and sheltered from microwave energy by a conveyor choke, may convey the materials to be heated to the container. Also, preferably, the floor of the resonant cavity may include perforatins, so that the offgases and dust generated in the apparatus may be removed from the resonant cavity by pulling outside air between the container choke and the exterior wall of the container into the resonant cavity and out from the cavity through the perforations.

The extraction of essential oil from patchouli leaves (Pogostemon cablin Benth) using microwave hydrodistillation and solvent-free microwave extraction methods

NASA Astrophysics Data System (ADS)

Putri, D. K. Y.; Kusuma, H. S.; Syahputra, M. E.; Parasandi, D.; Mahfud, M.

2017-12-01

Patchouli plant (Pogostemon cablin Benth) is one of the important essential oil-producing plant, contributes more than 50% of total exports of Indonesia’s essential oil. However, the extraction of patchouli oil that has been done in Indonesia is generally still used conventional methods that require enormous amount of energy, high solvent usage, and long time of extraction. Therefore, in this study, patchouli oil extraction was carried out by using microwave hydrodistillation and solvent-free microwave extraction methods. Based on this research, it is known that the extraction of patchouli oil using microwave hydrodistillation method with longer extraction time (240 min) only produced patchouli oil’s yield 1.2 times greater than solvent-free microwave extraction method which require faster extraction time (120 min). Otherwise the analysis of electric consumption and the environmental impact, the solvent-free microwave extraction method showed a smaller amount when compared with microwave hydrodistillation method. It is conclude that the use of solvent-free microwave extraction method for patchouli oil extraction is suitably method as a new green technique.

Orthodontic instrument sterilization with microwave irradiation

PubMed Central

Yezdani, Arif; Mahalakshmi, Krishnan; Padmavathy, Kesavaram

2015-01-01

Objective: This study was designed to evaluate the efficiency of microwave sterilization of orthodontic instruments and molar bands immersed in plain distilled water with and without oral rinse, and to ascertain the minimum time of exposure required to sterilize. Materials and Methods: The orthodontic instruments (hinged and nonhinged), molar bands and mouth mirrorsused in the patient 's mouth were selected for the study. The instruments were divided into two groups – Group I with oral rinse-set A (0.01% chlorhexidine gluconate) and set B (0.025% betadine) and Group II (included sets C and D without oral rinse). The instruments of set A, B and C were microwaved at 2,450 MHz, 800 W for 5 min, whereas, set D was microwaved for 10 min at the same above mentioned specifications. The efficacy of sterilization was assessed by stab inoculation of the instruments onto trypticase soya agar plates. The plates were checked for bacterial growth following incubation at 37 °C for 24 h. For sterility control,Geobacillus stearothermophilus (MTCC 1518) was included. Results: No growth was observed in the plates that were inoculated with the microwaved orthodontic instruments of sets A, B and D, whereas scanty bacterial growth was observed in the plates inoculatedwith the microwaved set C instruments. Conclusion: Effective sterilization was achieved when the orthodontic instruments and molar bands were immersed in distilled water without oral rinse and microwaved for 10 min as also for those that were immersed in distilled water with oral rinse and microwaved for 5 min. PMID:26015686

Microwave Frequency Polarizers

NASA Technical Reports Server (NTRS)

Ha, Vien The; Mirel, Paul; Kogut, Alan J.

2013-01-01

This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

Microwave Sky image from the WMAP Mission

NASA Technical Reports Server (NTRS)

2005-01-01

A detailed full-sky map of the oldest light in the universe. It is a 'baby picture' of the universe. Colors indicate 'warmer' (red) and 'cooler' (blue) spots. The oval shape is a projection to display the whole sky; similar to the way the globe of the earth can be projected as an oval. The microwave light captured in this picture is from 379,000 years after the Big Bang, over 13 billion years ago. For more information, see http://map.gsfc.nasa.gov/m_mm/mr_whatsthat.html

Image formation in microwave holography

NASA Technical Reports Server (NTRS)

Cribbs, R. W.; Lamb, B. L.

1973-01-01

Microwave holograms are made without offset reference beam, but it has been found that Van der Lugt filter can be used to produce image offset. Also, filter permits "decoding" of holograms in contrast with usual practice of reconstructing visible-light analogs of original micro-wave wave fronts.

Continuous microwave flow synthesis of mesoporous hydroxyapatite.

PubMed

Akram, Muhammad; Alshemary, Ammar Z; Goh, Yi-Fan; Wan Ibrahim, Wan Aini; Lintang, Hendrik O; Hussain, Rafaqat

2015-11-01

We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca(2+) ion released in SBF solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermoregulation in intense microwave fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michaelson, S.M.

1981-10-01

These studies clearly indicate the thermoregulatory capacity of the dog to withstand exposure to high microwave fields at specific absorption rates (SAR) of 3.7 and 6.1 W/kg. It appears that adequate thermoregulation takes place at an SAR of 3.7 W/kg but only transiently at 6.1 W/kg. These values, compared with the standardized resting metabolic rate of 3.29 W/kg (0.75), provide a basis for assessing the relationship of the thermal burden and thermo-regulatory disruption by microwaves in the dog. To elucidate the thermal potential of microwave exposure, it was helpful to conduct these exposures at various ambient temperatures in which themore » normal body temperature remained stable, thus permitting comparison of heat production and dissipation with our without microwaves. The zone of the thermal neutrality or thermoneutral zone of vasomotor activity, 22-26.5 deg C, where body temperature is regulated by changes in vasomotor tonus, fulfilled this requirement.« less

Microwave Palaeointensity Experiments On Terrestrial and Martian Material

NASA Astrophysics Data System (ADS)

Shaw, J.; Hill, M.; Gratton, M.

The microwave palaeointensity technique was developed in Liverpool University (Walton et al 1996) and has successfully been applied to archaeological ceramics and recent lavas (Shaw et al 1996, 1999.; Hill et al 1999,2000). These published results show that microwave analysis provides accurate palaeointensity determinations com- bined with a very high success rate. Most recently the technique has been successfully applied to Martian material (Shaw et al, 2001) to look for the existence of an internal Martian dynamo early in Martian history. New experiments have been carried out us- ing microwaves to demagnetise synthetic muti-component TRM's and new palaeoin- tensity experiments providing a comparison between microwave analysis of laboratory TRM's and conventional thermal Thellier analysis of microwave generated mTRM's. These experiments demonstrate the equivalence of microwave and thermally gener- ated TRM's. D. Walton, S Snape, T.C. Rolph, J. Shaw and J.A. Share, Application of ferromagnetic resonance heating to palaeointensity determinations.1996, Phys Earth Planet Int,94, 183-186. J. Shaw, D. Walton, S Yang, T.C.Rolph, and J.A. Share. Microwave Archaeointensities from Peruvian Ceramics. 1996, Geophys. J. Int,124,241-244 J. Shaw, S. Yang, T. C. Rolph, and F. Y. Sun. A comparison of archaeointensity results from Chinese ceramics using Microwave and conventional ThellierSs and ShawSs methods.,1999, G J Int.136, 714-718 M. Hill, and J. Shaw, 1999, Palaeointensity results for Historic Lavas from Mt. Etna using microwave demagnetisation/remagnetisation in a modified Thellier type exper- iment. G. J. Int, 139, 583-590 M. J. Hill, and J. Shaw, 2000. Magnetic field intensity study of the 1960 Kilauea lava flow, Hawaii, using the microwave palaeointensity technique, Geophys. J. Int., 142, 487-504. J. Shaw, M. Hill, and S. J. Openshaw, 2001, Investigating the ancient Martian magnetic field using microwaves, Earth and Planetary Science Letters 190 (2001) 103-109

Plant Response to Microwaves at 2.45 GHz

NASA Technical Reports Server (NTRS)

Skiles, J. W.

2003-01-01

One method of beaming to Earth energy captured by Space Solar Power (SSP) satellites is by using microwaves. Since microwaves are non-ioniz ing and of low energy they probably will have little or no direct eff ect (either long- or short-term) on terrestrial biota. This contentio n must to be proved however, before the public will accept a continuo us beam of microwaves being sent to the ground near populated areas or onto agricultural lands. To begin to address this question, an exper iment has been done that exposed an important agronomic plant speaes (alfalfa, Medicago sativa L.) to a continuous microwave beam at 2.45 GHz and from between 0.5 to 1.2 milli-watts per square centimeter. Th e hypothesis was that plants exposed to microwaves will be no differe nt from those control plants that were not exposed to microwaves. The microwaves were broadcast over a tray of mature, growing plants in the laboratory. The control plants were subjected to the same environme ntal conditions (light, temperature, soil and nutrients) minus the mi crowave exposure. Both populations of plants were watered as needed. As may be seen, the experiment was designed so that the only variable to which the test plants were subjected was microwave exposure. Prec ise, non-destructive measurements were taken of leaf chlorophyll concentration over the period of the experiment. Also measured were gross plant variables such as stem length, internodal distance, and, at the end of the experiment, above-ground biomass, both fresh and dry weig hts. Soil temperatures on bare soil and under the plant canopy were a lso measured. After seven weeks of exposure to microwaves there was n o sigruficant difference between control and test plant populations. A number of other plant/ microwave exposure studies will be discussed in this presentation. However, this experiment is one of the few publ ished examples of organisms being exposed to continuos microwave illu mination at one of the proposed SSP microwave

Microwave SQUID multiplexer demonstration for cosmic microwave background imagers

NASA Astrophysics Data System (ADS)

Dober, B.; Becker, D. T.; Bennett, D. A.; Bryan, S. A.; Duff, S. M.; Gard, J. D.; Hays-Wehle, J. P.; Hilton, G. C.; Hubmayr, J.; Mates, J. A. B.; Reintsema, C. D.; Vale, L. R.; Ullom, J. N.

2017-12-01

Key performance characteristics are demonstrated for the microwave superconducting quantum interference device (SQUID) multiplexer (μmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the μmux produces a white, input referred current noise level of 29 pA/ √{H z } at a microwave probe tone power of -77 dB, which is well below the expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure 98 pA/ √{H z } in the TES-coupled channels biased at 65% of the sensor normal resistance. This noise level is consistent with that predicted from bolometer thermal fluctuation (i.e., phonon) noise. Furthermore, the power spectral density is white over a range of frequencies down to ˜100 mHz, which enables CMB mapping on large angular scales that constrain the physics of inflation. Additionally, we report cross-talk measurements that indicate a level below 0.3%, which is less than the level of cross-talk from multiplexed readout systems in deployed CMB imagers. These measurements demonstrate the μmux as a viable readout technique for future CMB imaging instruments.

High-Power Microwave Transmission and Mode Conversion Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vernon, Ronald J.

2015-08-14

This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design formore » high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.« less

Microwave drying of wood strands

Treesearch

Guanben Du; Siqun Wang; Zhiyong Cai

2005-01-01

Characteristics of microwave drying of wood strands with different initial moisture contents and geometries were investigated using a commercial small microwave oven under different power inputs. Temperature and moisture changes along with the drying efficiency were examined at different drying scenarios. Extractives were analyzed using gas chromatography=mass...

[Experimental study on spectra of compressed air microwave plasma].

PubMed

Liu, Yong-Xi; Zhang, Gui-Xin; Wang, Qiang; Hou, Ling-Yun

2013-03-01

Using a microwave plasma generator, compressed air microwave plasma was excited under 1 - 5 atm pressures. Under different pressures and different incident microwave power, the emission spectra of compressed air microwave plasma were studied with a spectra measuring system. The results show that continuum is significant at atmospheric pressure and the characteristic will be weakened as the pressure increases. The band spectra intensity will be reduced with the falling of the incident microwave power and the band spectra were still significant. The experimental results are valuable to studying the characteristics of compressed air microwave plasma and the generating conditions of NO active groups.

Progress Towards Microwave Ignition of Explosives

NASA Astrophysics Data System (ADS)

Curling, Mark; Collins, Adam; Dima, Gabriel; Proud, William

2009-06-01

Microwaves could provide a method of propellant ignition that does away with a traditional primer, making ammunition safer and suitable for Insensitive Munitions (IM) applications. By embedding a suitable material inside a propellant, it is postulated that microwaves could be used to stimulate hotspots, through direct heating or electrostatic discharge (arcing) across the energetic material. This paper reports on progress in finding these suitable materials. Graphite rod, magnetite cubes and powders of graphite, aluminium, copper oxide, and iron were irradiated in a conventional microwave oven. Temperature measurements were made using a shielded thermocouple and thermal paints. Only graphite rod and magnetite showed significant heating upon microwave exposure. The light output from arcing of iron, steel, iron pyrite, magnetite and graphite was measured in the same microwave oven as above. Sample mass and shape were correlated with arcing intensity. A strategy is proposed to create a homogeneous igniter material by embedding arcing materials within an insulator, Polymethylpentene (TPX). External discharges were transmitted through TPX, however no embedded samples were successful in generating an electrical breakdown suitable for propellant ignition.

Microwave radiative transfer studies of precipitation

NASA Technical Reports Server (NTRS)

Bringi, V. N.; Vivekanandan, J.; Turk, F. Joseph

1993-01-01

Since the deployment of the DMSP SSM/I microwave imagers in 1987, increased utilization of passive microwave radiometry throughout the 10 - 100 GHz spectrum has occurred for measurement of atmospheric constituents and terrestrial surfaces. Our efforts have focused on observations and analysis of the microwave radiative transfer behavior of precipitating clouds. We have focused particular attention on combining both aircraft and SSM/I radiometer imagery with ground-based multiparameter radar observations. As part of this and the past NASA contract, we have developed a multi-stream, polarized radiative transfer model which incorporates scattering. The model has the capability to be initialized with cloud model output or multiparameter radar products. This model provides the necessary 'link' between the passive microwave radiometer and active microwave radar observations. This unique arrangement has allowed the brightness temperatures (TB) to be compared against quantities such as rainfall, liquid/ice water paths, and the vertical structure of the cloud. Quantification of the amounts of ice and water in precipitating clouds is required for understanding of the global energy balance.

Microwave Triggered Laser Ionization of Air

NASA Astrophysics Data System (ADS)

Vadiee, Ehsan; Prasad, Sarita; Jerald Buchenauer, C.; Schamiloglu, Edl

2012-10-01

The goal of this work is to study the evolution and dynamics of plasma expansion when a high power microwave (HPM) pulse is overlapped in time and space on a very small, localized region of plasma formed by a high energy laser pulse. The pulsed Nd:YAG laser (8 ns, 600mJ, repetition rate 10 Hz) is focused to generate plasma filaments in air with electron density of 10^17/cm^3. When irradiated with a high power microwave pulse these electrons would gain enough kinetic energy and further escalate avalanche ionization of air due to elastic electron-neutral collisions thereby causing an increased volumetric discharge region. An X-band relativistic backward wave oscillator(RBWO) at the Pulsed Power,Beams and Microwaves laboratory at UNM is constructed as the microwave source. The RBWO produces a microwave pulse of maximum power 400 MW, frequency of 10.1 GHz, and energy of 6.8 Joules. Special care is being given to synchronize the RBWO and the pulsed laser system in order to achieve a high degree of spatial and temporal overlap. A photodiode and a microwave waveguide detector will be used to ensure the overlap. Also, a new shadowgraph technique with a nanosecond time resolution will be used to detect changes in the shock wave fronts when the HPM signal overlaps the laser pulse in time and space.

1990 MTT-S International Microwave Symposium and Exhibition and Microwave and Millimeter-Wave Monolithic IC Symposium, Dallas, TX, May 7-10, 1990, Proceedings

NASA Astrophysics Data System (ADS)

McQuiddy, David N., Jr.; Sokolov, Vladimir

1990-12-01

The present conference discusses microwave filters, lightwave technology for microwave antennas, planar and quasi-planar guides, mixers and VCOs, cavity filters, discontinuity and coupling effects, control circuits, power dividers and phase shifters, microwave ICs, biological effects and medical applications, CAD and modeling for MMICs, directional couplers, MMIC design trends, microwave packaging and manufacturing, monolithic ICs, and solid-state devices and circuits. Also discussed are microwave and mm-wave superconducting technology, MICs for communication systems, the merging of optical and microwave technologies, microwave power transistors, ferrite devices, network measurements, advanced transmission-line structures, FET devices and circuits, field theory of IC discontinuities, active quasi-optical techniques, phased-array techniques and circuits, nonlinear CAD, sub-mm wave devices, and high power devices.

Constraints on wrapped Dirac-Born-Infeld inflation in a warped throat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, Takeshi; Mukohyama, Shinji; Kinoshita, Shunichiro, E-mail: tkobayashi@utap.phys.s.u-tokyo.ac.jp, E-mail: mukoyama@phys.s.u-tokyo.ac.jp, E-mail: kinoshita@utap.phys.s.u-tokyo.ac.jp

2008-01-15

We derive constraints on the tensor to scalar ratio and on the background charge of the warped throat for Dirac-Born-Infeld inflation driven by D5- and D7-branes wrapped over cycles of the throat. It is shown that background charge well beyond the known maximal value is required in most cases for Dirac-Born-Infeld inflation to generate cosmological observables compatible with the WMAP3 (Wilkinson Microwave Anisotropy Probe 3) data. Most of the results derived in this paper are insensitive to the details of the inflaton potential, and could be applied to generic warped throats.

Selection of biological indicator for validating microwave heating sterilization.

PubMed

Sasaki, K; Mori, Y; Honda, W; Miyake, Y

1998-01-01

For the purpose of selecting an appropriate biological indicator for evaluation of the effects of microwave heating sterilization, we examined aerobic bacterial spores to determine whether microwaves have non-thermal sterilization effects. After microwave irradiation on dry bacterial spores (three species), none of the bacterial spores were killed. The survival rate of the spores after microwave irradiation of spore suspensions (twelve species) was compared with that after heating by a conventional method. The order of heat resistance in the bacterial species was similar between the two heating methods. Bacillus stearothermophilus spores were the most heat-resistant. These results suggest that microwaves have no non-thermal sterilization effects on bacterial spores, the specific resistant spores to microwave heating, and microwave heating sterilization can be evaluated in the same way as for conventional heating sterilization. As a biological indicator for evaluation of overkill sterilization, B. stearothermophilus spores may be appropriate for microwave heating sterilization as well as steam sterilization.

Summer Arctic sea ice character from satellite microwave data

NASA Technical Reports Server (NTRS)

Carsey, F. D.

1985-01-01

It is pointed out that Arctic sea ice and its environment undergo a number of changes during the summer period. Some of these changes affect the ice cover properties and, in turn, their response to thermal and mechanical forcing throughout the year. The main objective of this investigation is related to the development of a method for estimating the areal coverage of exposed ice, melt ponds, and leads, which are the basic surface variables determining the local surface albedo. The study is based on data obtained in a field investigation conducted from Mould Bay (NWT), Nimbus 5 satellite data, and Seasat data. The investigation demonstrates that microwave data from satellites, especially microwave brightness temperature, provide good data for estimating important characteristics of summer sea ice cover.

Some comments on passive microwave measurement of rain

NASA Technical Reports Server (NTRS)

Wilheit, Thomas T.

1986-01-01

It is argued that because microwave radiation interacts much more strongly with hydrometeors than with cloud particles, microwave measurements from space offer a significant chance of making global precipitation estimates. Over oceans, passive microwave measurements are essentially attenuation measurements that can be very closely related to the rain rate independently of the details of the drop-size distribution. Over land, scattering of microwave radiation by the hydrometeors, especially in the ice phase, can be used to estimate rainfall. In scattering, the details of the drop-size distribution are very important and it is therefore more difficult to achieve a high degree of accuracy. The SSM/I (Special Sensor Microwave Imager), a passive microwave imaging sensor that will be launched soon, will have dual-polarized channels at 85.5 GHz that will be very sensitive to scattering by frozen hydrometeors. Other sensors being considered for the future space missions would extend the ability to estimate rain rates from space. The ideal spaceborne precipitation-measurement system would use the complementary strengths of passive microwave, radar, and visible/infrared measurements.

A microwave plasma torch and its applications

NASA Astrophysics Data System (ADS)

Uhm, H. S.; Hong, Y. C.; Shin, D. H.

2006-05-01

A portable microwave plasma torch at atmospheric pressure by making use of magnetrons operated at 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used in various areas including commercial, environmental and military applications. For example, perfluorocompounds (PFCs), which have long lifetimes and serious global warming implications, are widely used during plasma etching and plasma-assisted chamber cleaning processes in chemical vapour deposition systems. The microwave torch effectively eliminates PFCs. Efficient decomposition of toluene gas indicates the effectiveness of volatile organic compound eliminations from industrial emission and the elimination of airborne chemical and biological warfare agents. The microwave torch has been used to synthesize carbon nanotubes in an on-line system, thereby providing the opportunity of mass production of the nanotubes. There are other applications of the microwave plasma torch.

Complete remission of skin lesions in a patient with subcorneal pustular dermatosis (Sneddon-Wilkinson disease) treated with antimyeloma therapy: association with disappearance of M-protein.

PubMed

von dem Borne, P A; Jonkman, M F; van Doorn, R

2017-05-01

Subcorneal pustular dermatosis (SPD), or Sneddon-Wilkinson disease, is a rare pustular skin disease that follows a chronic relapsing course. A well-known association exists between SPD and IgA monoclonal gammopathy of undetermined significance (MGUS), which exists in up to 40% of cases. SPD has also been observed in patients with IgA myeloma. In SPD, direct and indirect immunofluorescence studies do not reveal in vivo bound IgA to the epithelial cell surface, in contrast to IgA pemphigus, which has similar clinicopathological features. Here we describe the case of a male patient with SPD and a concurrent IgA MGUS who had been treated with dapsone for 20 years with frequent relapses. Following development of multiple myeloma, the patient was treated with intensive antimyeloma treatment consisting of high-dose melphalan with autologous stem cell transplantation. This resulted in a complete remission of the myeloma with disappearance of the M-protein. In addition, a sustained remission of SPD was achieved without further treatment. Twenty-eight months after melphalan therapy the M-protein reappeared in the serum, and 2 months later SPD reappeared with histopathologically proven skin lesions at predilection sites. Presence and absence of skin lesions was found to correlate with the presence and absence of the M-protein in the serum. This is the first report of antimyeloma therapy inducing a long-lasting remission in SPD. The findings in this patient strongly suggest a causal role for circulating IgA antibodies in the pathogenesis of SPD. Antimyeloma treatment should be considered in patients with IgA MGUS-associated SPD refractory to other therapies. © 2016 British Association of Dermatologists.

Development of Si(1-x)Ge(x) technology for microwave sensing applications

NASA Technical Reports Server (NTRS)

Mena, Rafael A.; Taub, Susan R.; Alterovitz, Samuel A.; Young, Paul E.; Simons, Rainee N.; Rosenfeld, David

1993-01-01

The progress for the first year of the work done under the Director's Discretionary Fund (DDF) research project entitled, 'Development of Si(1-x)Ge(x) Technology for Microwave Sensing Applications.' This project includes basic material characterization studies of silicon-germanium (SiGe), device processing on both silicon (Si) and SiGe substrates, and microwave characterization of transmission lines on silicon substrates. The material characterization studies consisted of ellipsometric and magneto-transport measurements and theoretical calculations of the SiGe band-structure. The device fabrication efforts consisted of establishing SiGe device processing capabilities in the Lewis cleanroom. The characterization of microwave transmission lines included studying the losses of various coplanar transmission lines and the development of transitions on silicon. Each part of the project is discussed individually and the findings for each part are presented. Future directions are also discussed.

Wideband Agile Digital Microwave Radiometer

NASA Technical Reports Server (NTRS)

Gaier, Todd C.; Brown, Shannon T.; Ruf, Christopher; Gross, Steven

2012-01-01

The objectives of this work were to take the initial steps needed to develop a field programmable gate array (FPGA)- based wideband digital radiometer backend (>500 MHz bandwidth) that will enable passive microwave observations with minimal performance degradation in a radiofrequency-interference (RFI)-rich environment. As manmade RF emissions increase over time and fill more of the microwave spectrum, microwave radiometer science applications will be increasingly impacted in a negative way, and the current generation of spaceborne microwave radiometers that use broadband analog back ends will become severely compromised or unusable over an increasing fraction of time on orbit. There is a need to develop a digital radiometer back end that, for each observation period, uses digital signal processing (DSP) algorithms to identify the maximum amount of RFI-free spectrum across the radiometer band to preserve bandwidth to minimize radiometer noise (which is inversely related to the bandwidth). Ultimately, the objective is to incorporate all processing necessary in the back end to take contaminated input spectra and produce a single output value free of manmade signals to minimize data rates for spaceborne radiometer missions. But, to meet these objectives, several intermediate processing algorithms had to be developed, and their performance characterized relative to typical brightness temperature accuracy re quirements for current and future microwave radiometer missions, including those for measuring salinity, soil moisture, and snow pack.

Vortices at Microwave Frequencies

NASA Astrophysics Data System (ADS)

Silva, Enrico; Pompeo, Nicola; Dobrovolskiy, Oleksandr V.

2017-11-01

The behavior of vortices at microwave frequencies is an extremely useful source of information on the microscopic parameters that enter the description of the vortex dynamics. This feature has acquired particular relevance since the discovery of unusual superconductors, such as cuprates. Microwave investigation then extended its field of application to many families of superconductors, including the artificially nanostructured materials. It is then important to understand the basics of the physics of vortices moving at high frequency, as well as to understand what information the experiments can yield (and what they can not). The aim of this brief review is to introduce the readers to some basic aspects of the physics of vortices under a microwave electromagnetic field, and to guide them to an understanding of the experiment, also by means of the illustration of some relevant results.

High efficiency FET microwave detector design

NASA Astrophysics Data System (ADS)

Luglio, Juan; Ishii, Thomas Koryu

1990-12-01

The work is based on an assumption that very little microwave power would be consumed at a negatively biased gate of a microwave FET, yet significant detected signals would be obtained at the drain if the bias is given. By analyzing a Taylor-series expansion of the drain-current equation in the vicinity of a fixed gate-bias voltage, the bias voltage is found to maximize the second derivative of the drain current, the gate-bias voltage characteristic curve for the maximum detected drain current under a given fixed drain-bias voltage. Based on these findings, a high-efficiency microwave detector is designed, fabricated, and tested at 8.6 GHz, and it is shown that the audio power over absorbed microwave power ratio of the detector is 135 percent due to the positive gain.

Free-space microwave-power transmission

NASA Technical Reports Server (NTRS)

Brown, W. C.

1976-01-01

Laboratory-scale wireless transmission of microwave power approaches fifty-four percent efficiency. DC is converted to a 2.45-GHz signal and is transmitted through horn antenna array; microwave signal is received at rectenna and is simultaneously collected and rectified back to dc at receiving sites; dc is then processed for wired distribution.

More Experiments with Microwave Ovens

ERIC Educational Resources Information Center

Vollmer, Michael; Mollmann, Klaus-Peter; Karstadt, Detlef

2004-01-01

Microwave ovens can be used to perform exciting demonstrations that illustrate a variety of physics topics. Experiments discussed here show superheating, visualize the inhomogeneous heating that takes place in a microwave and also show how to use a mobile phone to detect radiation leaking from the oven. Finally eggs can give some spectacular…

[Application of microwave irradiation technology to the field of pharmaceutics].

PubMed

Zhang, Xue-Bing; Shi, Nian-Qiu; Yang, Zhi-Qiang; Wang, Xing-Lin

2014-03-01

Microwaves can be directly transformed into heat inside materials because of their ability of penetrating into any substance. The degree that materials are heated depends on their dielectric properties. Materials with high dielectric loss are more easily to reach a resonant state by microwaves field, then microwaves can be absorbed efficiently. Microwave irradiation technique with the unique heating mechanisms could induce drug-polymer interaction and change the properties of dissolution. Many benefits such as improving product quality, increasing energy efficiency and reducing times can be obtained by microwaves. This paper summarized characteristics of the microwave irradiation technique, new preparation techniques and formulation process in pharmaceutical industry by microwave irradiation technology. The microwave technology provides a new clue for heating and drying in the field of pharmaceutics.

Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques.

PubMed

Mohammed, Muzaffer; Clement, Travis C; Aslan, Kadir

2014-12-02

In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400-800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72-24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally.

Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques

PubMed Central

Mohammed, Muzaffer; Clement, Travis C.; Aslan, Kadir

2014-01-01

In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400–800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72–24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally. PMID:25568813

[Impact of microwave dealing with the cutting surface on the hepatocellular carcinoma recurrence after hepatectomy].

PubMed

Wu, Zhengshan; Wang, Xing; Wang, Dong; Fan, Ye; Li, Donghua; Kong, Lianbao; Wang, Xuehao; Wang, Ke

2015-12-01

To explore the impact of microwave dealing with cutting surface on perioperative liver function recovery and recurrence and metastasis after hepatectomy for HCC. Clinical data of 133 patients with HCC from March 2009 to November 2010 were retrospectively analyzed. They were divided into the conventional surgery group (66 cases) and microwave treatment group (67 cases). A domestic ECO-100 microwave knife was inserted into the liver cutting surface 0.5 cm from the cutting edge, and repeated multi-point burning with an average time of 25 minutes in the microwave treatment group. Then the perioperative liver function recovery and recurrence and metastasis in the two groups were compared. The operation time of conventional surgery group was (158.0 ± 31.0) minutes, and that of microwave treatment group was significantly longer (181.0 ± 28.0) minutes (P=0.027). There were no significant differences in the liver function recovery between the two groups (P>0.05). There were 6 cases of recurrence and metastasis after 6 months and 9 cases after 12 months in the microwave treatment group, while there were 15 cases of recurrence and metastasis after 6 months and 20 cases after 12 months in the conventional surgery group, showing a significant difference (P=0.034 and 0.022, respectively). Microwave dealing with the cutting surface has no significant effect on perioperative liver function recovery in hepatectomy. However, microwave treatment can reduce the in situ recurrence in HCC patients within the first year after surgery, indicating a good clinical application value.

Microwave sintering of multiple articles

DOEpatents

Blake, Rodger D.; Katz, Joel D.

1993-01-01

Apparatus and method for producing articles of alumina and of alumina and silicon carbide in which the articles are sintered at high temperatures using microwave radiation. The articles are placed in a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

Combination microwave ovens: an innovative design strategy.

PubMed

Tinga, Wayne R; Eke, Ken

2012-01-01

Reducing the sensitivity of microwave oven heating and cooking performance to load volume, load placement and load properties has been a long-standing challenge for microwave and microwave-convection oven designers. Conventional design problem and solution methods are reviewed to provide greater insight into the challenge and optimum operation of a microwave oven after which a new strategy is introduced. In this methodology, a special load isolating and energy modulating device called a transducer-exciter is used containing an iris, a launch box, a phase, amplitude and frequency modulator and a coupling plate designed to provide spatially distributed coupling to the oven. This system, when applied to a combined microwave-convection oven, gives astounding performance improvements to all kinds of baked and roasted foods including sensitive items such as cakes and pastries, with the only compromise being a reasonable reduction in the maximum available microwave power. Large and small metal utensils can be used in the oven with minimal or no performance penalty on energy uniformity and cooking results. Cooking times are greatly reduced from those in conventional ovens while maintaining excellent cooking performance.

Microwave-induced formation of oligomeric amyloid aggregates.

PubMed

Lee, Wonseok; Choi, Yeseong; Lee, Sang Won; Kim, Insu; Lee, Dongtak; Hong, Yoochan; Lee, Gyudo; Yoon, Dae Sung

2018-08-24

Amyloid aggregates have emerged as a significant hallmark of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Although it has been recently reported that microwave heating induces amyloid aggregation compared with conventional heating methods, the mechanism of amyloid aggregate induction has remained unclear. In this study, we investigated the formation of oligomeric amyloid aggregates (OAAs) by microwave irradiation at microscale volumes of solution. Microwave irradiation of protein monomer solution triggered rapid formation of OAAs within 7 min. We characterized the formation of OAAs using atomic force microscopy, thioflavin T fluorescent assay and circular dichroism. In the microwave system, we also investigated the inhibitory effect on the formation of amyloid aggregates by L-ascorbic acid as well as enhanced amyloid aggregation by silver nanomaterials such as nanoparticles and nanowires. We believe that microwave technology has the potential to facilitate the study of amyloid aggregation in the presence of chemical agents or nanomaterials.

Red palm oil production by microwave irradiation

NASA Astrophysics Data System (ADS)

Sarah, M.; Widyastuti, S.; Ningsih, D.

2018-02-01

Preliminary study of red palm oil (RPO) production from palm fruitlets by microwave irradiation carried out in domestic microwave oven equipped with thermocouple. The various mass of fruitlets (800, 900 and 1000 g) were heated for 10-18 minutes with 2 minutes interval and microwave power of 400, 560 and 800 Watt respectively. Heated fruitlets were pressed by hydraulic presser to obtain RPO. This study observed heating time parameter was more crucial to RPO quality rather than temperature. Prolonged heating degraded carotenoids in the fruitlets during heating process yielded less carotenoids content in the palm oil. The best time and microwave power combination to produce RPO in this study was 14 minutes and 800 Watt respectively which yielded 11.67% RPO with 1.27% FFA content and carotenoids concentration of 1219.37 ppm. Overall, RPO production by microwave irradiation proceeded faster as compared to conventional process.

NORSEX 1979 microwave remote sensing data report

NASA Technical Reports Server (NTRS)

Hennigar, H. F.; Schaffner, S. K.

1982-01-01

Airborne microwave remote sensing measurements obtained by NASA Langley Research Center in support of the 1979 Norwegian Remote Sensing Experiment (NORSEX) are summarized. The objectives of NORSEX were to investigate the capabilities of an active/passive microwave system to measure ice concentration and type in the vicinity of the marginal ice zone near Svalbard, Norway and to apply microwave techniques to the investigation of a thermal oceanic front near Bear Island, Norway. The instruments used during NORSEX include the stepped frequency microwave radiometer, airborne microwave scatterometer, precision radiation thermometer and metric aerial photography. The data are inventoried, summarized, and presented in a user-friendly format. Data summaries are presented as time-history plots which indicate when and where data were obtained as well as the sensor configuration. All data are available on nine-track computer tapes in card-image format upon request to the NASA Langley Technical Library.

Kilometric shock-associated events and microwave bursts

NASA Technical Reports Server (NTRS)

Kundu, M. R.; Macdowall, R. J.; Stone, R. G.

1990-01-01

The peak times of impulsive microwaves bursts are compared with those of shock-associated (SA) kilometric radio events. The first peaks in these two frequency regimes are usually well-correlated in time, but the last peaks of the SA events observed at 1 MHz occur an average of 20 min after the last impulsive microwave peaks. In some cases, the SA events overlap in time with the post-burst increases of microwave bursts; sometimes there is general correspondence in their intensity time profiles. These observations suggest that the earlier components of the SA events are usually caused by electrons accelerated in or near the microwave source region. The possibility that the later components of some SA events could be associated with nonthermal electrons responsible for microwave post-burst increases, although they have traditionally been attributed to electrons accelerated at type II burst producing shocks in the upper corona is discussed.

Microwave Ovens

MedlinePlus

... Commission (CPSC) Website Laws, Regulations & Standards Manufacturers of electronic radiation emitting products sold in the United States ... and Cosmetic Act (FFDCA), Chapter V, Subchapter C - Electronic Product Radiation Control . Manufacturers of microwave ovens are ...

Magnetometer Based on Optoelectronic Microwave Oscillator

NASA Technical Reports Server (NTRS)

Maleki, Lute; Strekalov, Dmitry; Matsko, Andrey

2005-01-01

proposed instrument, intended mainly for use as a magnetometer, would include an optoelectronic oscillator (OEO) stabilized by an atomic cell that could play the role of a magnetically tunable microwave filter. The microwave frequency would vary with the magnetic field in the cell, thereby providing an indication of the magnetic field. The proposed magnetometer would offer a combination of high accuracy and high sensitivity, characterized by flux densities of less than a picotesla. In comparison with prior magnetometers, the proposed magnetometer could, in principle, be constructed as a compact, lightweight instrument: It could fit into a package of about 10 by 10 by 10 cm and would have a mass <0.5 kg. As described in several prior NASA Tech Briefs articles, an OEO is a hybrid of photonic and electronic components that generates highly spectrally pure microwave radiation, and optical radiation modulated by the microwave radiation, through direct conversion between laser light and microwave radiation in an optoelectronic feedback loop. As used here, "atomic cell" signifies a cell containing a vapor, the constituent atoms of which can be made to undergo transitions between quantum states, denoted hyperfine levels, when excited by light in a suitable wavelength range. The laser light must be in this range. The energy difference between the hyperfine levels defines the microwave frequency. In the proposed instrument (see figure), light from a laser would be introduced into an electro-optical modulator (EOM). Amplitude-modulated light from the exit port of the EOM would pass through a fiber-optic splitter having two output branches. The light in one branch would be sent through an atomic cell to a photodiode. The light in the other branch would constitute the microwave-modulated optical output. Part of the light leaving the atomic cell could also be used to stabilize the laser at a frequency in the vicinity of the desired hyperfine or other quantum transition. The

A light-induced microwave oscillator

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1995-01-01

We describe a novel oscillator that converts continuous light energy into sta ble and spectrally pure microwave signals. This light-induced microwave oscillator (LIMO) consists of a pump laser and a feedback circuit, including an intensity modulator, an optical fiber delay line, a photodetector, an amplifier, and a filter. We develop a quasilinear theory and obtain expressions for the threshold condition, the amplitude, the frequency, the line width, and the spectral power density of the oscillation. We also present experimental data to compare with the theoretical results. Our findings indicate that the LIMO can generate ultrastable, spectrally pure microwave reference signals up to 75 GHz with a phase noise lower than -140 dBc/Hz at 10 kHz.

Compact Microwave Fourier Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

2009-01-01

A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

Portable microwave instrument for non-destructive evaluation of structural characteristics

DOEpatents

Bible, D.W.; Crutcher, R.I.; Sohns, C.W.; Maddox, S.R.

1995-01-24

A portable microwave instrument for evaluating characteristics of a structural member includes a source of microwave energy, a transmitter coupled to the source of microwave energy for transmitting a microwave signal at the structural member, and a receiver positioned on the same side of the structural member as the transmitter and being disposed to receive a microwave signal reflected by the structural member. A phase angle difference is determined between the transmitted microwave signal and the received microwave signal using a signal splitter and a balanced mixer. The difference in phase angle varies in accordance with differences in size, shape and locations of constituent materials within the structural member. 6 figures.

Portable microwave instrument for non-destructive evaluation of structural characteristics

DOEpatents

Bible, Don W.; Crutcher, Richard I.; Sohns, Carl W.; Maddox, Stephen R.

1995-01-01

A portable microwave instrument for evaluating characteristics of a structural member includes a source of microwave energy, a transmitter coupled to the source of microwave energy for transmitting a microwave signal at the structural member, and a receiver positioned on the same side of the structural member as the transmitter and being disposed to receive a microwave signal reflected by the structural member. A phase angle difference is determined between the transmitted microwave signal and the received microwave signal using a signal splitter and a balanced mixer. The difference in phase angle varies in accordance with differences in size, shape and locations of constituent materials within the structural member.

High power microwave generator

DOEpatents

Ekdahl, Carl A.

1986-01-01

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

High power microwave generator

DOEpatents

Ekdahl, C.A.

1983-12-29

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

On-Chip Microwave Quantum Hall Circulator

NASA Astrophysics Data System (ADS)

Mahoney, A. C.; Colless, J. I.; Pauka, S. J.; Hornibrook, J. M.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.; Doherty, A. C.; Reilly, D. J.

2017-01-01

Circulators are nonreciprocal circuit elements that are integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their nonreciprocity arises from the interference of microwaves over the centimeter scale of the signal wavelength, in the presence of bulky magnetic media that breaks time-reversal symmetry. Here, we realize a completely passive on-chip microwave circulator with size 1 /1000 th the wavelength by exploiting the chiral, "slow-light" response of a two-dimensional electron gas in the quantum Hall regime. For an integrated GaAs device with 330 μ m diameter and about 1-GHz center frequency, a nonreciprocity of 25 dB is observed over a 50-MHz bandwidth. Furthermore, the nonreciprocity can be dynamically tuned by varying the voltage at the port, an aspect that may enable reconfigurable passive routing of microwave signals on chip.

A Review of Microwave-Assisted Reactions for Biodiesel Production.

PubMed

Nomanbhay, Saifuddin; Ong, Mei Yin

2017-06-15

The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society's increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to accomplish superior outcomes over the conventional methods in biodiesel production is presented. A green process for biodiesel production using a non-catalytic method is still new and very costly because of the supercritical condition requirement. Hence, non-catalytic biodiesel conversion under ambient pressure using microwave technology must be developed, as the energy utilization for microwave-based biodiesel synthesis is reported to be lower and cost-effective.

Asymmetrical penetration of microwave in a conducting media and determination of microwave conductivity for very thin samples using electron spin resonance

NASA Astrophysics Data System (ADS)

Seridonio, A. C.; Walmsley, L.

2001-04-01

Dyson's theory of conduction electron spin resonance (CESR) has been used in the limit d≤δ (d being the thickness of the sample and δ the skin depth of the microwave field) to obtain the microwave conductivity from the (A/B) ratio of the CESR absorbed power derivative. In this work we calculate the CESR absorbed power derivative using Kaplan's approach and show that the (A/B) ratio can be enhanced if asymmetrical penetration of microwave is used, which means that the microwave field enters into the sample from one of the faces. Therefore, the determination of the microwave conductivity from the (A/B) ratio of the CESR line can be performed for thinner samples. Experimentally, asymmetrical penetration can be obtained if one of the sample's faces is covered with a thin gold layer. The determination of microwave conductivity in conducting polymers films is among the possible applications of this method.

Microwave meta-atom enhanced spintronic rectification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gou, Peng; Xi, Fuchun; Qian, Qinbai

2015-04-06

An artificial meta-atom (MA), or alternatively, a plasmonic antenna, has been demonstrated to significantly enhance the microwave spin rectifying photovoltage by more than two orders in magnitude (∼280) in the ferromagnetic resonance regime. The large enhancement is attributed to the unique structure of the MA which magnifies both microwave electric (∼5) and magnetic (∼56) fields in the same near-field spatial region. Our work develops the interdisciplinary direction with artificial and natural magnetism and may find promising applications in high-frequency or opto-spintronic devices and wireless microwave energy harvesting.

Volumetric Near-Field Microwave Plasma Generation

NASA Technical Reports Server (NTRS)

Exton, R. J.; Balla, R. Jeffrey; Herring, G. C.; Popovic, S.; Vuskovic, L.

2003-01-01

A periodic series of microwave-induced plasmoids is generated using the outgoing wave from a microwave horn and the reflected wave from a nearby on-axis concave reflector. The plasmoids are spaced at half-wavelength separations according to a standing-wave pattern. The plasmoids are enhanced by an effective focusing in the near field of the horn (Fresnel region) as a result of a diffractive narrowing. Optical imaging, electron density, and rotational temperature measurements characterize the near field plasma region. Volumetric microwave discharges may have application to combustion ignition in scramjet engines.

Remote measurement of microwave distribution based on optical detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Zhong; Ding, Wenzheng; Yang, Sihua

2016-01-04

In this letter, we present the development of a remote microwave measurement system. This method employs an arc discharge lamp that serves as an energy converter from microwave to visible light, which can propagate without transmission medium. Observed with a charge coupled device, quantitative microwave power distribution can be achieved when the operators and electronic instruments are in a distance from the high power region in order to reduce the potential risk. We perform the experiments using pulsed microwaves, and the results show that the system response is dependent on the microwave intensity over a certain range. Most importantly, themore » microwave distribution can be monitored in real time by optical observation of the response of a one-dimensional lamp array. The characteristics of low cost, a wide detection bandwidth, remote measurement, and room temperature operation make the system a preferred detector for microwave applications.« less

A measurement of the cosmic microwave background damping tail from the 2500-square-degree SPT-SZ survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Story, K. T.; Keisler, R.; Benson, B. A.

2013-12-10

We present a measurement of the cosmic microwave background (CMB) temperature power spectrum using data from the recently completed South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. This measurement is made from observations of 2540 deg{sup 2} of sky with arcminute resolution at 150 GHz, and improves upon previous measurements using the SPT by tripling the sky area. We report CMB temperature anisotropy power over the multipole range 650 < ℓ < 3000. We fit the SPT bandpowers, combined with the 7 yr Wilkinson Microwave Anisotropy Probe (WMAP7) data, with a six-parameter ΛCDM cosmological model and find that the two datasets aremore » consistent and well fit by the model. Adding SPT measurements significantly improves ΛCDM parameter constraints; in particular, the constraint on θ {sub s} tightens by a factor of 2.7. The impact of gravitational lensing is detected at 8.1σ, the most significant detection to date. This sensitivity of the SPT+WMAP7 data to lensing by large-scale structure at low redshifts allows us to constrain the mean curvature of the observable universe with CMB data alone to be Ω{sub k}=−0.003{sub −0.018}{sup +0.014}. Using the SPT+WMAP7 data, we measure the spectral index of scalar fluctuations to be n{sub s} = 0.9623 ± 0.0097 in the ΛCDM model, a 3.9σ preference for a scale-dependent spectrum with n{sub s} < 1. The SPT measurement of the CMB damping tail helps break the degeneracy that exists between the tensor-to-scalar ratio r and n{sub s} in large-scale CMB measurements, leading to an upper limit of r < 0.18 (95% C.L.) in the ΛCDM+r model. Adding low-redshift measurements of the Hubble constant (H {sub 0}) and the baryon acoustic oscillation (BAO) feature to the SPT+WMAP7 data leads to further improvements. The combination of SPT+WMAP7+H {sub 0}+BAO constrains n{sub s} = 0.9538 ± 0.0081 in the ΛCDM model, a 5.7σ detection of n{sub s} < 1, and places an upper limit of r < 0.11 (95% C.L.) in the ΛCDM+r model. These new

Inactivation of Clostridium difficile spores by microwave irradiation.

PubMed

Ojha, Suvash Chandra; Chankhamhaengdecha, Surang; Singhakaew, Sombat; Ounjai, Puey; Janvilisri, Tavan

2016-04-01

Spores are a potent agent for Clostridium difficile transmission. Therefore, factors inhibiting spores have been of continued interest. In the present study, we investigated the influence of microwave irradiation in addition to conductive heating for C. difficile spore inactivation in aqueous suspension. The spores of 15 C. difficile isolates from different host origins were exposed to conductive heating and microwave irradiation. The complete inhibition of spore viability at 10(7) CFU/ml was encountered following microwave treatment at 800 W for 60 s, but was not observed in the conductive-heated spores at the same time-temperature exposure. The distinct patterns of ultrastructural alterations following microwave and conductive heat treatment were observed and the degree of damages by microwave was in the exposure time-dependent manner. Microwave would therefore be a simple and time-efficient tool to inactivate C. difficile spores, thus reducing the risk of C. difficile transmission. Copyright © 2015 Elsevier Ltd. All rights reserved.

Uniform bulk material processing using multimode microwave radiation

DOEpatents

Varma, Ravi; Vaughn, Worth E.

2000-01-01

An apparatus for generating uniform heating in material contained in a cylindrical vessel is described. TE.sub.10 -mode microwave radiation is coupled into a cylindrical microwave transition such that microwave radiation having TE.sub.11 -, TE.sub.01 - and TM.sub.01 -cylindrical modes is excited therein. By adjusting the intensities of these modes, substantially uniform heating of materials contained in a cylindrical drum which is coupled to the microwave transition through a rotatable choke can be achieved. The use of a poor microwave absorbing insulating cylindrical insert, such as aluminum oxide, for separating the material in the container from the container walls and for providing a volume through which air is circulated is expected to maintain the container walls at room temperature. The use of layer of highly microwave absorbing material, such as SiC, inside of the insulating insert and facing the material to be heated is calculated to improve the heating pattern of the present apparatus.

MICROWAVES IN GREEN AND SUSTAINABLE CHEMISTRY

EPA Science Inventory

In this chapter, we have outlined roles of microwave chemistry in the establishment of green and sustainable chemistry. Many examples, mostly from the authors' laboratories, have been presented of green microwave processes under solvent-free conditions or with solvents, including...

Antartic sea ice, 1973 - 1976: Satellite passive-microwave observations

NASA Technical Reports Server (NTRS)

Zwally, H. J.; Comiso, J. C.; Parkinson, C. L.; Campbell, W. J.; Carsey, F. D.; Gloersen, P.

1983-01-01

Data from the Electrically Scanning Microwave Radiometer (ESMR) on the Nimbus 5 satellite are used to determine the extent and distribution of Antarctic sea ice. The characteristics of the southern ocean, the mathematical formulas used to obtain quantitative sea ice concentrations, the general characteristics of the seasonal sea ice growth/decay cycle and regional differences, and the observed seasonal growth/decay cycle for individual years and interannual variations of the ice cover are discussed. The sea ice data from the ESMR are presented in the form of color-coded maps of the Antarctic and the southern oceans. The maps show brightness temperatures and concentrations of pack ice averaged for each month, 4-year monthly averages, and month-to-month changes. Graphs summarizing the results, such as areas of sea ice as a function of time in the various sectors of the southern ocean are included. The images demonstrate that satellite microwave data provide unique information on large-scale sea ice conditions for determining climatic conditions in polar regions and possible global climatic changes.

Microwave-excited ultrasound and thermoacoustic dual imaging

NASA Astrophysics Data System (ADS)

Ding, Wenzheng; Ji, Zhong; Xing, Da

2017-05-01

We designed a microwave-excited ultrasound (MUI) and thermoacoustic dual imaging system. Under the pulsed microwave excitation, the piezoelectric transducer used for thermoacoustic signal detection will also emit a highly directional ultrasonic beam based on the inverse piezoelectric effect. With this beam, the ultrasonic transmitter circuitry of the traditional ultrasound imaging (TUI) system can be replaced by a microwave source. In other words, TUI can be fully integrated into the thermoacoustic imaging system by sharing the microwave excitation source and the transducer. Moreover, the signals of the two imaging modalities do not interfere with each other due to the existence of the sound path difference, so that MUI can be performed simultaneously with microwave-induced thermoacoustic imaging. In the study, the performance characteristics and imaging capabilities of this hybrid system are demonstrated. The results indicate that our design provides one easy method for low-cost platform integration and has the potential to offer a clinically useful dual-modality tool for the detection of accurate diseases.

Variations in West Antarctic Ice Front and Passive Microwave Brightness Temperature for 8 Years Duration in 2000s

NASA Astrophysics Data System (ADS)

Kim, J.; Yu, J.; Wang, L.; Liu, H.

2017-12-01

Changes in Antarctic ice sheet are caused by various reasons such as changes in Holocene climate, precipitation, and ocean temperature. Such issues of changes in ice sheet has been mainly focused on the Antarctic peninsula, and it is known that ice retreat of the area is caused by changes in atmospheric and ocean temperatures. For the case of West Antarctica, ice front change research is relatively rarely conducted except the Pine island glacier area. This study has monitored ice front changes of West Antarctica and compared the patterns with the changes in brightness temperature based on remote sensing techniques. We used 2000 Radarsat-1 and 2008 Rasarsat-2 SAR data to delineate coastlines of whole West Antarctica based on the locally thresholding adaptive algorithm. The delineated coast lines are analyzed to figure out ice front change patterns between the duration. The variations in brightness temperature for the same duration are calculated based on Defense Meteorological Satellite Program (DMSP)'s Special Sensor Microwave/Images-Special Sensor Microwave Imager/Sounder (SSM/I-SSMIS) passive microwave data. The results show ice front of West Antarctica shows advancing trend except the pine island glacier area. The brightness temperature had decreasing trend during the study period. It infers that changes in ice front and brightness temperature of West Antarctica have considerable relationships. It is expected that a long term monitoring of the relationship would contribute understanding ice dynamics of West Antarctica significantly.

Snow Microwave Radiative Transfer (SMRT): A new model framework to simulate snow-microwave interactions for active and passive remote sensing applications

NASA Astrophysics Data System (ADS)

Loewe, H.; Picard, G.; Sandells, M. J.; Mätzler, C.; Kontu, A.; Dumont, M.; Maslanka, W.; Morin, S.; Essery, R.; Lemmetyinen, J.; Wiesmann, A.; Floury, N.; Kern, M.

2016-12-01

Forward modeling of snow-microwave interactions is widely used to interpret microwave remote sensing data from active and passive sensors. Though different models are yet available for that purpose, a joint effort has been undertaken in the past two years within the ESA Project "Microstructural origin of electromagnetic signatures in microwave remote sensing of snow". The new Snow Microwave Radiative Transfer (SMRT) model primarily facilitates a flexible treatment of snow microstructure as seen by X-ray tomography and seeks to unite respective advantages of existing models. In its main setting, SMRT considers radiation transfer in a plane-parallel snowpack consisting of homogeneous layers with a layer microstructure represented by an autocorrelation function. The electromagnetic model, which underlies permittivity, absorption and scattering calculations within a layer, is based on the improved Born approximation. The resulting vector-radiative transfer equation in the snowpack is solved using spectral decomposition of the discrete ordinates discretization. SMRT is implemented in Python and employs an object-oriented, modular design which intends to i) provide an intuitive and fail-safe API for basic users ii) enable efficient community developments for extensions (e.g. for improvements of sub-models for microstructure, permittivity, soil or interface reflectivity) from advanced users and iii) encapsulate the numerical core which is maintained by the developers. For cross-validation and inter-model comparison, SMRT implements various ingredients of existing models as selectable options (e.g. Rayleigh or DMRT-QCA phase functions) and shallow wrappers to invoke legacy model code directly (MEMLS, DMRT-QMS, HUT). In this paper we give an overview of the model components and show examples and results from different validation schemes.

Afferent Mechanisms of Microwave-Induced Biological Effects.

DTIC Science & Technology

1987-08-12

an effect by treatment with low doses of narcotic antagonist (naloxone or naltrexone ) was used as a criterion for the involvement of endogenous...block number) kEffects of low -level microwave irradiation on neurological function wer-LinesTrgated in the- rat. Results can be summarized in the...effects of microwave exposure and may have important implications in certain occupational situations in which repeated exposure to low -level microwaves is

Q-band 4-state phase shifter in planar technology: Circuit design and performance analysis.

PubMed

Villa, E; Cagigas, J; Aja, B; de la Fuente, L; Artal, E

2016-09-01

A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90.7°, -181.7°, and 88.5° within the operation band, 35-47 GHz, and mean insertion loss of 7.4 dB. The performance of its integration in a polarimetric receiver for radio astronomy is analyzed, which validates the use of the presented phase shifter in such type of receiver.

Reconstruction of CMB temperature anisotropies with primordial CMB induced polarization in galaxy clusters

NASA Astrophysics Data System (ADS)

Liu, Guo-Chin; Ichiki, Kiyotomo; Tashiro, Hiroyuki; Sugiyama, Naoshi

2016-07-01

Scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces polarization signals determined by the quadrupole anisotropy in the photon distribution at the location of clusters. This `remote quadrupole' derived from the measurements of the induced polarization in galaxy clusters provides an opportunity to reconstruct local CMB temperature anisotropies. In this Letter, we develop an algorithm of the reconstruction through the estimation of the underlying primordial gravitational potential, which is the origin of the CMB temperature and polarization fluctuations and CMB induced polarization in galaxy clusters. We found a nice reconstruction for the quadrupole and octopole components of the CMB temperature anisotropies with the assistance of the CMB induced polarization signals. The reconstruction can be an important consistency test on the puzzles of CMB anomalies, especially for the low-quadrupole and axis-of-evil problems reported in Wilkinson Microwave Anisotropy Probe and Planck data.

Method and apparatus for thickness measurement using microwaves

DOEpatents

Woskov, Paul [Bedford, MA; Lamar, David A [West Richland, WA

2001-01-01

The method for measuring the thickness of a material which transmits a detectable amount of microwave radiation includes irradiating the material with coherent microwave radiation tuned over a frequency range. Reflected microwave radiation is detected, the reflected radiation having maxima and minima over the frequency range as a result of coherent interference of microwaves reflected from reflecting surfaces of the material. The thickness of the material is determined from the period of the maxima and minima along with knowledge of the index of refraction of the material.

Mobile system for microwave removal of concrete surfaces

DOEpatents

White, Terry L.; Bigelow, Timothy S.; Schaich, Charles R.; Foster, Jr., Don

1997-01-01

A method and apparatus for the microwave removal of contaminated concrete surfaces. The apparatus comprises a housing adapted to pass over a support surface. The housing includes a waveguide for directing microwave energy to the surface at an angle maximizing absorption of microwave energy by the surface. The apparatus is further provided with a source of microwave energy operably associated with the waveguide, wherein the microwave energy has a frequency of between about 10.6 GHz and about 24 GHz and acts to remove the uppermost layer from the surface. The apparatus further includes a debris containment assembly comprising a vacuum assembly operably associated with the housing. The vacuum assembly is adapted to remove debris from the area adjacent the surface.

Mobile system for microwave removal of concrete surfaces

DOEpatents

White, T.L.; Bigelow, T.S.; Schaich, C.R.; Foster, D. Jr.

1997-06-03

A method and apparatus are disclosed for the microwave removal of contaminated concrete surfaces. The apparatus comprises a housing adapted to pass over a support surface. The housing includes a waveguide for directing microwave energy to the surface at an angle maximizing absorption of microwave energy by the surface. The apparatus is further provided with a source of microwave energy operably associated with the waveguide, wherein the microwave energy has a frequency of between about 10.6 GHz and about 24 GHz and acts to remove the uppermost layer from the surface. The apparatus further includes a debris containment assembly comprising a vacuum assembly operably associated with the housing. The vacuum assembly is adapted to remove debris from the area adjacent the surface. 7 figs.

Development of anatomically and dielectrically accurate breast phantoms for microwave imaging applications

NASA Astrophysics Data System (ADS)

O'Halloran, M.; Lohfeld, S.; Ruvio, G.; Browne, J.; Krewer, F.; Ribeiro, C. O.; Inacio Pita, V. C.; Conceicao, R. C.; Jones, E.; Glavin, M.

2014-05-01

Breast cancer is one of the most common cancers in women. In the United States alone, it accounts for 31% of new cancer cases, and is second only to lung cancer as the leading cause of deaths in American women. More than 184,000 new cases of breast cancer are diagnosed each year resulting in approximately 41,000 deaths. Early detection and intervention is one of the most significant factors in improving the survival rates and quality of life experienced by breast cancer sufferers, since this is the time when treatment is most effective. One of the most promising breast imaging modalities is microwave imaging. The physical basis of active microwave imaging is the dielectric contrast between normal and malignant breast tissue that exists at microwave frequencies. The dielectric contrast is mainly due to the increased water content present in the cancerous tissue. Microwave imaging is non-ionizing, does not require breast compression, is less invasive than X-ray mammography, and is potentially low cost. While several prototype microwave breast imaging systems are currently in various stages of development, the design and fabrication of anatomically and dielectrically representative breast phantoms to evaluate these systems is often problematic. While some existing phantoms are composed of dielectrically representative materials, they rarely accurately represent the shape and size of a typical breast. Conversely, several phantoms have been developed to accurately model the shape of the human breast, but have inappropriate dielectric properties. This study will brie y review existing phantoms before describing the development of a more accurate and practical breast phantom for the evaluation of microwave breast imaging systems.

Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

PubMed Central

2016-01-01

Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2–20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20–39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation. PMID:27917407

Two-Band, Low-Loss Microwave Window

NASA Technical Reports Server (NTRS)

Britcliffe, Michael; Franco, Manuel

2007-01-01

A window for a high-sensitivity microwave receiving system allows microwave radiation to pass through to a cryogenically cooled microwave feed system in a vacuum chamber, while keeping ambient air out of the chamber and helping to keep the interior of the chamber cold. The microwave feed system comprises a feed horn and a low-noise amplifier, both of which are required to be cooled to a temperature of 15 K during operation. The window is designed to exhibit very little microwave attenuation in two frequency bands: 8 to 9 GHz and 30 to 40 GHz. The window is 15 cm in diameter. It includes three layers (see figure): 1) The outer layer is made of a poly(tetrafluoroethylene) film 0.025 mm thick. This layer serves primarily to reflect and absorb solar ultraviolet radiation to prolong the life of the underlying main window layer, which is made of a polyimide that becomes weakened when exposed to ultraviolet. The poly(tetrafluoroethylene) layer also protects the main window layer against abrasion. Moreover, the inherent hydrophobicity of poly(tetrafluoroethylene) helps to prevent the highly undesirable accumulation of water on the outer surface. 2) The polyimide main window layer is 0.08 mm thick. This layer provides the vacuum seal for the window. 3) A 20-mm-thick layer of ethylene/ propylene copolymer foam underlies the main polyimide window layer. This foam layer acts partly as a thermal insulator: it limits radiational heating of the microwave feed horn and, concomitantly, limits radiational cooling of the window. This layer has high compressive strength and provides some mechanical support for the main window layer, reducing the strength required of the main window layer. The ethylene/propylene copolymer foam layer is attached to an aluminum window ring by means of epoxy. The outer poly(tetrafluoroethylene) film and the main polyimide window layer are sandwiched together and pressed against the window ring by use of a bolted clamp ring. The window has been found to

Radiofrequency/Microwave Radiation Biological Effects and Safety Standards: A Review

DTIC Science & Technology

1994-06-01

reported that a 50 year old woman had developed cataracts after intermittent exposure to a 2.45 GHz microwave oven. The incident power density levels were...include: Survelance, Communications, Command and Control, Intelligence, Signal Processing, Computer Sience and Technology, Electrom Technology, Photoracs and laiity Saences. S* I l I

Microwave Thermal Propulsion

NASA Technical Reports Server (NTRS)

Parkin, Kevin L. G.; Lambot, Thomas

2017-01-01

We have conducted research in microwave thermal propulsion as part of the space exploration access technologies (SEAT) research program, a cooperative agreement (NNX09AF52A) between NASA and Carnegie Mellon University. The SEAT program commenced on the 19th of February 2009 and concluded on the 30th of September 2015. The DARPA/NASA Millimeter-wave Thermal Launch System (MTLS) project subsumed the SEAT program from May 2012 to March 2014 and one of us (Parkin) served as its principal investigator and chief engineer. The MTLS project had no final report of its own, so we have included the MTLS work in this report and incorporate its conclusions here. In the six years from 2009 until 2015 there has been significant progress in millimeter-wave thermal rocketry (a subset of microwave thermal rocketry), most of which has been made under the auspices of the SEAT and MTLS programs. This final report is intended for multiple audiences. For researchers, we present techniques that we have developed to simplify and quantify the performance of thermal rockets and their constituent technologies. For program managers, we detail the facilities that we have built and the outcomes of experiments that were conducted using them. We also include incomplete and unfruitful lines of research. For decision-makers, we introduce the millimeter-wave thermal rocket in historical context. Considering the economic significance of space launch, we present a brief but significant cost-benefit analysis, for the first time showing that there is a compelling economic case for replacing conventional rockets with millimeter-wave thermal rockets.

Microwave surface resistance of MgB2

NASA Astrophysics Data System (ADS)

Zhukov, A. A.; Purnell, A.; Miyoshi, Y.; Bugoslavsky, Y.; Lockman, Z.; Berenov, A.; Zhai, H. Y.; Christen, H. M.; Paranthaman, M. P.; Lowndes, D. H.; Jo, M. H.; Blamire, M. G.; Hao, Ling; Gallop, J.; MacManus-Driscoll, J. L.; Cohen, L. F.

2002-04-01

The microwave power and frequency dependence of the surface resistance of MgB2 films and powder samples were studied. Sample quality is relatively easy to identify by the breakdown in the ω2 law for poor-quality samples at all temperatures. The performance of MgB2 at 10 GHz and 21 K was compared directly with that of high-quality YBCO films. The surface resistance of MgB2 was found to be approximately three times higher at low microwave power and showed an onset of nonlinearity at microwave surface fields ten times lower than the YBCO film. It is clear that MgB2 films are not yet optimized for microwave applications.

Microwave Pretreatment For Hydrolysis Of Cellulose

NASA Technical Reports Server (NTRS)

Cullingford, Hatice S.; George, Clifford E.; Lightsey, George R.

1993-01-01

Microwave pretreatment enhances enzymatic hydrolysis of cellulosic wastes into soluble saccharides used as feedstocks for foods, fuels, and other products. Low consumption of energy, high yield, and low risk of proposed hydrolysis process incorporating microwave pretreatment makes process viable alternative to composting.

Magnetic Tunnel Junction-Based On-Chip Microwave Phase and Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Fan, Xin; Chen, Yunpeng; Xie, Yunsong; Kolodzey, James; Wilson, Jeffrey D.; Simons, Rainee N.; Xiao, John Q.

2014-01-01

A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance, the frequency of an incident microwave is directly determined. In addition, by integrating a mixer circuit, the MTJ-based microwave detector can also determine the relative phase between two microwave signals. Thus, the MTJ-based microwave detector can be used as an on-chip microwave phase and spectrum analyzer.

Magnetic Tunnel Junction-Based On-Chip Microwave Phase and Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Fan, Xin; Chen, Yunpeng; Xie, Yunsong; Kolodzey, James; Wilson, Jeffrey D.; Simons, Rainee N.; Xiao, John Q.

2014-01-01

A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance, the frequency of an incident microwave is directly determined. In addition, by integrating a mixer circuit, the MTJ-based microwave detector can also determine the relative phase between two microwave signals. Thus, the MTJbased microwave detector can be used as an on-chip microwave phase and spectrum analyzer.

Microwave-to-Optical Conversion in WGM Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy; Strekalov, Dmitry; Yu, Nan; Matsko, Andrey; Maleki, Lute

2008-01-01

Microwave-to-optical frequency converters based on whispering-gallery-mode (WGM) resonators have been proposed as mixers for the input ends of microwave receivers in which, downstream of the input ends, signals would be processed photonically. A frequency converter as proposed (see figure) would exploit the nonlinearity of the electromagnetic response of a WGM resonator made of LiNbO3 or another suitable ferroelectric material. Up-conversion would take place by three-wave mixing in the resonator. The WGM resonator would be de - signed and fabricated to obtain (1) resonance at both the microwave and the optical operating frequencies and (2) phase matching among the input and output microwave and optical signals as described in the immediately preceding article. Because the resonator would be all dielectric there would be no metal electrodes signal losses would be very low and, consequently, the resonance quality factors (Q values) of the microwave and optical fields would be very large. The long lifetimes associated with the large Q values would enable attainment of high efficiency of nonlinear interaction with low saturation power. It is anticipated that efficiency would be especially well enhanced by the combination of optical and microwave resonances in operation at input signal frequencies between 90 and 300 GHz.

A Review of Microwave-Assisted Reactions for Biodiesel Production

PubMed Central

Nomanbhay, Saifuddin; Ong, Mei Yin

2017-01-01

The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to accomplish superior outcomes over the conventional methods in biodiesel production is presented. A green process for biodiesel production using a non-catalytic method is still new and very costly because of the supercritical condition requirement. Hence, non-catalytic biodiesel conversion under ambient pressure using microwave technology must be developed, as the energy utilization for microwave-based biodiesel synthesis is reported to be lower and cost-effective. PMID:28952536

Classification methods for monitoring Arctic sea ice using OKEAN passive/active two-channel microwave data

USGS Publications Warehouse

Belchansky, Gennady I.; Douglas, David C.

2000-01-01

This paper presents methods for classifying Arctic sea ice using both passive and active (2-channel) microwave imagery acquired by the Russian OKEAN 01 polar-orbiting satellite series. Methods and results are compared to sea ice classifications derived from nearly coincident Special Sensor Microwave Imager (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) image data of the Barents, Kara, and Laptev Seas. The Russian OKEAN 01 satellite data were collected over weekly intervals during October 1995 through December 1997. Methods are presented for calibrating, georeferencing and classifying the raw active radar and passive microwave OKEAN 01 data, and for correcting the OKEAN 01 microwave radiometer calibration wedge based on concurrent 37 GHz horizontal polarization SSM/I brightness temperature data. Sea ice type and ice concentration algorithms utilized OKEAN's two-channel radar and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter, together with a priori knowledge about the scattering parameters and natural emissivities of basic sea ice types. OKEAN 01 data and algorithms tended to classify lower concentrations of young or first-year sea ice when concentrations were less than 60%, and to produce higher concentrations of multi-year sea ice when concentrations were greater than 40%, when compared to estimates produced from SSM/I data. Overall, total sea ice concentration maps derived independently from OKEAN 01, SSM/I, and AVHRR satellite imagery were all highly correlated, with uniform biases, and mean differences in total ice concentration of less than four percent (sd<15%).

Passive microwave remote sensing for sea ice research

NASA Technical Reports Server (NTRS)

1984-01-01

Techniques for gathering data by remote sensors on satellites utilized for sea ice research are summarized. Measurement of brightness temperatures by a passive microwave imager converted to maps of total sea ice concentration and to the areal fractions covered by first year and multiyear ice are described. Several ancillary observations, especially by means of automatic data buoys and submarines equipped with upward looking sonars, are needed to improve the validation and interpretation of satellite data. The design and performance characteristics of the Navy's Special Sensor Microwave Imager, expected to be in orbit in late 1985, are described. It is recommended that data from that instrument be processed to a form suitable for research applications and archived in a readily accessible form. The sea ice data products required for research purposes are described and recommendations for their archival and distribution to the scientific community are presented.

Thermal effects of X-band microwaves on skin tissues

NASA Astrophysics Data System (ADS)

Song, Kyo D.; Yoon, Hargsoon; Lee, Kunik; Kim, Jaehwan; Choi, Sang H.

2012-04-01

Microwave can be used as a power carrier to implanted medical devices wirelessly, which is regarded as one of the attractive features for medical applications. The loss mechanism of microwave transmission through lossy media often appears as a thermal effect due to the absorption of microwave. Such a thermal effect on human tissue has not rigorously studied yet. The thermal effect on living tissues was experimentally tested with animal skins to understand the absorption characteristics of microwave. In this paper, the frequency range of microwave used for the tests was from 6 GHz to 13 GHz.

Lightning control system using high power microwave FEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiho, M.; Watanbe, A.; Kawasaki, S.

A research project for developing a thunder lightning control system using an induction linac based high power microwave free electron laser (FEL) started at JAERI The system will produce weakly ionized plasma rod in the atmosphere by high power microwaves and control a lightning path, away from , e. g., nuclear power stations and rocket launchers. It has been known that about MW/cm{sup 2} power density is enough for the atmospheric breakdown in the microwave region, and which means high power microwave FEL with GW level output power is feasible for atmospheric breakdown, and accordingly is feasible for thunder lightningmore » control tool with making a conductive plasma channel in the atmosphere. From the microwave attenuation consideration in the atmosphere, FEL of 35GHz(0.13dB/km), 90GHz(0.35dB/km), 140GHz(1.7dB/km), and of 270 GHz(4.5dB/km) are the best candidates for the system. Comparing with other proposed lightning control system using visible or ultraviolet laser, the system using microwave has an advantage that microwave suffers smaller attenuation by rain or snow which always exist in the real atmospheric circumstances when lightning occurs.« less

Microwave Oven Experiments with Metals and Light Sources

ERIC Educational Resources Information Center

Vollmer, Michael; Mollmann, Klaus-Peter; Karstadt, Detlef

2004-01-01

"Don't put metal objects in the microwave" is common safety advice. But why? Here we describe demonstration experiments involving placing household metallic objects in a microwave oven. These allow a better understanding of the interaction of microwaves with materials. Light bulbs and discharge lamps can also be used in instructive demonstrations.

Active microwave responses - An aid in improved crop classification

NASA Technical Reports Server (NTRS)

Rosenthal, W. D.; Blanchard, B. J.

1984-01-01

A study determined the feasibility of using visible, infrared, and active microwave data to classify agricultural crops such as corn, sorghum, alfalfa, wheat stubble, millet, shortgrass pasture and bare soil. Visible through microwave data were collected by instruments on board the NASA C-130 aircraft over 40 agricultural fields near Guymon, OK in 1978 and Dalhart, TX in 1980. Results from stepwise and discriminant analysis techniques indicated 4.75 GHz, 1.6 GHz, and 0.4 GHz cross-polarized microwave frequencies were the microwave frequencies most sensitive to crop type differences. Inclusion of microwave data in visible and infrared classification models improved classification accuracy from 73 percent to 92 percent. Despite the results, further studies are needed during different growth stages to validate the visible, infrared, and active microwave responses to vegetation.

Microwave Cooking: Knowledge, Attitudes, and Practices of California Foods Teachers.

ERIC Educational Resources Information Center

Stalder, Laura D.; And Others

1990-01-01

A survey of 500 California secondary foods teachers (172 responses) indicated their understanding of microwave cooking principles and techniques and positive attitudes toward microwave cooking and safety. A majority used microwave instruction in their classrooms, although many indicated a need for ovens and microwave educational materials. (SK)

Highly Stable Wideband Microwave Extraction by Synchronizing Widely Tunable Optoelectronic Oscillator with Optical Frequency Comb

PubMed Central

Hou, D.; Xie, X. P.; Zhang, Y. L.; Wu, J. T.; Chen, Z. Y.; Zhao, J. Y.

2013-01-01

Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2 GHz to 4 GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18 fs and frequency instabilities at 1.2 × 10−15/1 s and 2.2 × 10−18/10000 s. PMID:24336459

Highly Stable Wideband Microwave Extraction by Synchronizing Widely Tunable Optoelectronic Oscillator with Optical Frequency Comb

NASA Astrophysics Data System (ADS)

Hou, D.; Xie, X. P.; Zhang, Y. L.; Wu, J. T.; Chen, Z. Y.; Zhao, J. Y.

2013-12-01

Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2 GHz to 4 GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18 fs and frequency instabilities at 1.2 × 10-15/1 s and 2.2 × 10-18/10000 s.

Microwave-induced cracking of pyrolytic tars coupled to microwave pyrolysis for syngas production.

PubMed

Beneroso, D; Bermúdez, J M; Montes-Morán, M A; Arenillas, A; Menéndez, J A

2016-10-01

Herein a new process is proposed to produce a syngas-rich gas fraction (>80vol% H2+CO) from biowaste based on microwave heating within two differentiated steps in order to avoid tars production. The first step consists of the microwave pyrolysis of biowaste induced by a char-based susceptor at 400-800°C; tars, char and syngas-rich gas fractions being produced. The tars are then fed into the second step where a portion of the char from the first step is used as a bed material in a 0.3:1wt% ratio. This bed is heated up by microwaves up to 800°C, allowing thermal cracking of tars and additional syngas (>90vol% H2+CO) being then produced. This new concept arises as an alternative technology to the gasification of biowastes for producing syngas with no need for catalysts or gasifying reagents to minimise tars production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anisotropy in the Microwave Sky at 90 GHz: Results from Python III

NASA Astrophysics Data System (ADS)

Platt, S. R.; Kovac, J.; Dragovan, M.; Peterson, J. B.; Ruhl, J. E.

1997-01-01

The third year of observations with the Python microwave background experiment densely samples a 5.5d × 22° region of sky that includes the fields measured during the first 2 years of observations with this instrument. The sky is sampled in two multipole bands centered at l ~ 87 and l ~ 170. These two data sets are analyzed to place limits on fluctuations in the microwave sky at 90 GHz. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we find flat-band power estimates of δTl ≡ [l(l + 1)Cl/(2π)]1/2 = 60+15-13 μK at l = 87+18-38 and δTl = 66+17-16 μK at l = 170+69-50. Combining the entire 3 year set of Python observations, we find that the angular power spectrum of fluctuations has a spectral index m = 0.16+.20-.18 and an amplitude δTle = 63+15-14 μK at le = 139+99-34 for the functional form δTl = δTle(l/le)m. The stated uncertainties in the amplitudes and spectral index represent 1 σ confidence intervals in the likelihood added in quadrature with a 20% calibration uncertainty and an estimate of the effects of a +/-0.05d uncertainty in the measured beamwidths. The limits of l are determined from the half-maximum points of the window functions.

Microwave bale moisture sensing: Field trial

USDA-ARS?s Scientific Manuscript database

A microwave moisture measurement technique was developed for moisture sensing of cotton bales after the bale press. The technique measures the propagation delay of a microwave signal that is transmitted through the cotton bale. This research conducted a field trial to test the sensor in a commercial...

Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression.

PubMed

Pall, Martin L

2016-09-01

/depressive symptoms, fatigue/tiredness, dysesthesia, concentration/attention dysfunction, memory changes, dizziness, irritability, loss of appetite/body weight, restlessness/anxiety, nausea, skin burning/tingling/dermographism and EEG changes. In summary, then, the mechanism of action of microwave EMFs, the role of the VGCCs in the brain, the impact of non-thermal EMFs on the brain, extensive epidemiological studies performed over the past 50 years, and five criteria testing for causality, all collectively show that various non-thermal microwave EMF exposures produce diverse neuropsychiatric effects. Copyright © 2015 The Author. Published by Elsevier B.V. All rights reserved.

Full-time response of starch subjected to microwave heating.

PubMed

Fan, Daming; Wang, Liyun; Zhang, Nana; Xiong, Lei; Huang, Luelue; Zhao, Jianxin; Wang, Mingfu; Zhang, Hao

2017-06-21

The effect of non-ionizing microwave radiation on starch is due to a gelatinization temperature range that changes starch structure and properties. However, the changes in starch upon microwave heating are observable throughout the heating process. We compared the effects on starch heating by microwaves to the effects by rapid and regular conventional heating. Our results show that microwave heating promotes the rapid rearrangement of starch molecules at low temperatures; starch showed a stable dielectric response and a high dielectric constant. Microwave heating changed the Cole-Cole curve and the polarization of starch suspension at low temperatures. A marked transition at 2.45 GHz resulted in a double-polarization phenomenon. At temperatures below gelatinization, microwave-induced dielectric rearrangement and changes in the polarization characteristics of starch suspensions reduced the absorption properties; at temperatures above gelatinization, these characteristics became consistent with conventional heating. Throughout the heating process, microwaves change the electrical response and polarization characteristics of the starch at low temperatures, but on the macro level, there is no enhancement of the material's microwave absorption properties. In contrast, with the warming process, the starch exhibited a "blocking effect", and the absorption properties of the starch quickly returned to the level observed in conductive heating after gelatinization.

Microwave reflection, transmission, and absorption by human brain tissue

NASA Astrophysics Data System (ADS)

Ansari, M. A.; Akhlaghipour, N.; Zarei, M.; Niknam, A. R.

2018-04-01

These days, the biological effects of electromagnetic (EM) radiations on the brain, especially in the frequency range of mobile communications, have caught the attention of many scientists. Therefore, in this paper, the propagation of mobile phone electromagnetic waves in the brain tissues is investigated analytically and numerically. The brain is modeled by three layers consisting of skull, grey and white matter. First, we have analytically calculated the microwave reflection, transmission, and absorption coefficients using signal flow graph technique. The effect of microwave frequency and variations in the thickness of layers on the propagation of microwave through brain are studied. Then, the penetration of microwave in the layers is numerically investigated by Monte Carlo method. It is shown that the analytical results are in good agreement with those obtained by Monte Carlo method. Our results indicate the absorbed microwave energy depends on microwave frequency and thickness of brain layers, and the absorption coefficient is optimized at a number of frequencies. These findings can be used for comparing the microwave absorbed energy in a child's and adult's brain.

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

PubMed Central

Lovingood, Derek D.; Owens, Jeffrey R.; Seeber, Michael; Kornev, Konstantin G.; Luzinov, Igor

2013-01-01

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces. PMID:24379052

Low-power microwave-mediated heating for microchip-based PCR.

PubMed

Marchiarullo, Daniel J; Sklavounos, Angelique H; Oh, Kyudam; Poe, Brian L; Barker, N Scott; Landers, James P

2013-09-07

Microwave energy has been used to rapidly heat food and drinks for decades, in addition to assisting other chemical reactions. However, only recently has microwave energy been applied in microfluidic systems to heat solution in reaction chambers, in particular, the polymerase chain reaction (PCR). One of the difficulties in developing microwave-mediated heating on a microchip is the construction of the appropriate architecture for delivery of the energy to specific micro-areas on the microchip. This work employs commercially-available microwave components commonly used in the wireless communications industry to generate a microwave signal, and a microstrip transmission line to deliver the energy to a 1 μL reaction chamber fabricated in plastic microdevices. A model was developed to create transmission lines that would optimally transmit energy to the reaction chamber at a given frequency, minimizing energy usage while focusing microwave delivery to the target chamber. Two different temperature control methods were demonstrated, varying microwave power or frequency. This system was used to amplify a fragment of the lambda-phage genome, thereby demonstrating its potential for integration into a portable PCR system.

Liver cancer: increased microwave delivery to ablation zone with cooled-shaft antenna--experimental and clinical studies.

PubMed

Kuang, Ming; Lu, Ming D; Xie, Xiao Y; Xu, Hui X; Mo, Li Q; Liu, Guang J; Xu, Zuo F; Zheng, Yan L; Liang, Jin Y

2007-03-01

To prospectively investigate whether the ablation zone induced with microwaves could be increased by delivering greater energy with a cooled-shaft antenna. All studies were animal care and ethics committee approved. Written informed consent was obtained from all patients. Microwave ablation was performed by using a cooled-shaft antenna in 48 ex vivo and 12 in vivo experiments with porcine livers. The coagulation diameters achieved in different microwave ablation parameter groups (60-90 W for 5-25 minutes) were compared. Ninety patients (78 men, 12 women; mean age, 53 years; age range, 20-82 years) with 133 0.8-8.0-cm (mean, 2.7 cm +/- 1.5 [standard deviation]) primary or metastatic liver cancers were treated with the same microwave ablation technique. Complete ablation (CA) and local tumor progression (LTP) rates were determined. Generalized estimating equations were used to compare differences in tumor size, ablation zone diameter, and CA and LTP rates between different patient subgroups. In the ex vivo livers, in vivo livers, and liver cancers, one application of microwave energy with 80 W for 25 minutes produced mean coagulation diameters of 5.6 x 7.4 cm, 3.5 x 5.9 cm, and 3.6 x 5.0 cm, respectively. Skin burn was not observed. CA rates in small (microwave energy with cooled-shaft antennas yielded large ablation zones in ex vivo and in vivo livers and in liver cancers. Effective local tumor control was achieved during one microwave ablation session. (c) RSNA, 2007.

Microwave resonance therapy in medical practice

NASA Astrophysics Data System (ADS)

Sumskoy, L. L.

1994-08-01

Consideration is being given to the problems of organizing treatment of patients with quantum medicine methods by Prof. S.P. Sit'ko at 660 hospitals of Ukraine and Russia. Analyzed are teaching of doctors and treatment of 250,000 patients for 82 nozologic cases in 1990 through 1993. In the State of Ukraine, the Government has adopted a State Target-oriented Program of Large- scale Promotion of Microwave Resonance Therapy Into Medical Practice as presented by the Ministry of Health care in 1989. According to the Program, it was planned, during the three year period, to provide MRT rooms in 325 medical institutions. The Program was based on a discovery by Prof. S.P. Sit'ko DSc (Physics & Mathematics), of a new non-morphological structure of man, i.e. an electromagnetic framework that is manifested by eigenfrequencies in the millimeter range and disturbance of which results in disease while repair returns the organism to health. This idea was subjected to national and international expert evaluation. This evaluation was done by a panel of 12 universally acknowledged scientists headed by the founder of the theory of superconductivity, professor of the Liverpool University (Great Britain) h. Frohlich and director of the Madrid medical center Prof. Alzina. The USA was represented by Dr. W. Rogers, chief of the Center of Radiation, Institute of Bioinformation Research. The stated that Professor S.P. Sit'ko and his coworkers had established a new line of inquiry in medicine, i.e. microwave resonance therapy. To implement the State Target-oriented Program, the Government chose the Interbranch Scientific and Engineering Center on Physics of the Alive and Microwave Resonance Therapy 'Vidhuk'.

Optimized ECR plasma apparatus with varied microwave window thickness

DOEpatents

Berry, Lee A.

1995-01-01

The present invention describes a technique to control the radial profile of microwave power in an ECR plasma discharge. In order to provide for a uniform plasma density to a specimen, uniform energy absorption by the plasma is desired. By controlling the radial profile of the microwave power transmitted through the microwave window of a reactor, the profile of the transmitted energy to the plasma can be controlled in order to have uniform energy absorption by the plasma. An advantage of controlling the profile using the window transmission characteristics is that variations to the radial profile of microwave power can be made without changing the microwave coupler or reactor design.

Trends of microwave dielectric materials for antenna application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulong, T. A. T., E-mail: tuanamirahtuansulong@gmail.com; Osman, R. A. M., E-mail: rozana@unimap.edu.my; Idris, M. S., E-mail: sobri@unimap.edu.my

Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ε{sub r}), high quality factor (Q {sub f} ≥ 5000 GH z) and good temperature coefficient of resonant frequency (τ{sub f}). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

21 CFR 1030.10 - Microwave ovens.

Code of Federal Regulations, 2012 CFR

2012-04-01

... after October 6, 1971. (b) Definitions—(1) Microwave oven means a device designed to heat, cook, or dry food through the application of electromagnetic energy at frequencies assigned by the Federal... prevent emission of microwave energy from the passage or opening which provides access to the cavity. (4...

21 CFR 1030.10 - Microwave ovens.

Code of Federal Regulations, 2014 CFR

2014-04-01

... after October 6, 1971. (b) Definitions—(1) Microwave oven means a device designed to heat, cook, or dry food through the application of electromagnetic energy at frequencies assigned by the Federal... prevent emission of microwave energy from the passage or opening which provides access to the cavity. (4...

21 CFR 1030.10 - Microwave ovens.

Code of Federal Regulations, 2013 CFR

2013-04-01

... after October 6, 1971. (b) Definitions—(1) Microwave oven means a device designed to heat, cook, or dry food through the application of electromagnetic energy at frequencies assigned by the Federal... prevent emission of microwave energy from the passage or opening which provides access to the cavity. (4...

Container for heat treating materials in microwave ovens

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.; Kimrey, Jr., Harold D.; Mills, James E.

1989-01-01

The efficiency of a microwave oven of a conventional two-source configuration and energy level is increased by providing the oven with a container for housing a refractory material to be treated. The container is formed of top and bottom walls transparent to microwaves while the sidewalls, in a circular configuration, are formed of a nonmetallic material opaque to microwave radiation reflecting the radiation penetrating the top and bottom walls radially inwardly into the center of the container wherein a casket of heat-insulating material is provided for housing the material to be heat treated. The reflection of the microwave radiation from the sidewalls increases the concentration of the microwaves upon the material being heat treated while the casket retains the heat to permit the heating of the material to a substantially higher temperature than achieveable in the oven without the container.

Development of a tactical high-power microwave source using the Plasma Electron Microwave Source (PEMS) concept

NASA Astrophysics Data System (ADS)

Dandl, R. A.; Guest, G. E.; Jory, H. R.

1990-12-01

The AMPHED facility was used to perform feasibility experiments to explore the generation of high-power microwave pulses from energy stored in a magnetic mirror plasma. The facility uses an open-ended magnetic mirror driven by pulsed or cw c- and x-band sources. Microwave horns were constructed to couple in the frequency range of 2.4 to 4 GHz to whistler waves in the plasma. Spontaneous bursts of microwave radiation in the range of 3 to 5 GHz were observed in the experiments. But the power levels were lower than expected for the whistler wave interaction. It is probable that the hot-electron energy densities achieved were not high enough to approach the threshold of the desired interaction.

Passive Microwave Remote Sensing of Soil Moisture

NASA Technical Reports Server (NTRS)

Njoku, Eni G.; Entekhabi, Dara

1996-01-01

Microwave remote sensing provides a unique capability for direct observation of soil moisture. Remote measurements from space afford the possibility of obtaining frequent, global sampling of soil moisture over a large fraction of the Earth's land surface. Microwave measurements have the benefit of being largely unaffected by cloud cover and variable surface solar illumination, but accurate soil moisture estimates are limited to regions that have either bare soil or low to moderate amounts of vegetation cover. A particular advantage of passive microwave sensors is that in the absence of significant vegetation cover soil moisture is the dominant effect on the received signal. The spatial resolutions of passive Microwave soil moisture sensors currently considered for space operation are in the range 10-20 km. The most useful frequency range for soil moisture sensing is 1-5 GHz. System design considerations include optimum choice of frequencies, polarizations, and scanning configurations, based on trade-offs between requirements for high vegetation penetration capability, freedom from electromagnetic interference, manageable antenna size and complexity, and the requirement that a sufficient number of information channels be available to correct for perturbing geophysical effects. This paper outlines the basic principles of the passive microwave technique for soil moisture sensing, and reviews briefly the status of current retrieval methods. Particularly promising are methods for optimally assimilating passive microwave data into hydrologic models. Further studies are needed to investigate the effects on microwave observations of within-footprint spatial heterogeneity of vegetation cover and subsurface soil characteristics, and to assess the limitations imposed by heterogeneity on the retrievability of large-scale soil moisture information from remote observations.

Springtime microwave emissivity changes in the southern Kara Sea

NASA Technical Reports Server (NTRS)

Crane, Robert G.; Anderson, Mark R.

1994-01-01

Springtime microwave brightness temperatures over first-year ice are examined for the southern Kara Sea. Snow emissivity changes are revealed by episodic drops in the 37- to 18-GHz brightness temperature gradient ratio measured by the Nimbus 7 scanning multichannel microwave radiometer. We suggest that the negative gradient ratios in spring 1982 result from increased scatter at 37 GHz due to the formation of a near-surface hoar layer. This interpretation is supported by the results of a surface radiation balance model that shows the melt signature occurring at below freezing temperatures but under clear-sky conditions with increased solar input to the surface. Published observations from the Greenland ice cap show a surface hoar layer forming under similar atmospheric conditions owing to the increased penetration and absorption of solar radiation just below the surface layer. In spring/early summer 1984 similar gradient ratio signatures occur. They appear to be due to several days of freeze-thaw cycling following the movement of a low-pressure system through the region. These changes in surface emissivity represent the transition from winter to summer conditions (as defined by the microwave response) and are shown to be regional in extent and to vary with the synoptic circulations.

Microwave fixation versus formalin fixation of surgical and autopsy tissue.

PubMed

Login, G R

1978-05-01

Microwave irradiation of surgical and autopsy tissue penetrates, fixes, and hardens the tissue almost immediately (the fluid media used in the microwave consisted of saline, ten percent phosphate buffered formalin, and distilled water). Tissue sections from a representative sample of organs were tested. Comparable sections were simultaneously fixed in a phosphate buffered ten percent formalin bath in a vaccum oven as a control. Hematoxylin and eosin were used to stain the sections. Results equal to and superior to the control method were obtained. Saline microwave fixation was superior to formalin microwave fixation. Tissues placed in Zenker's solution and fixed in standard microwave oven (for approximately one minute) yielded results at least equal to conventional Zenker fixation (approximately two hours). No tissue hardening resulted from Zenker microwave fixation. A unique time versus temperature graph (microwave heating curve) reduces individual variation with this technique.

Microwave coagulation therapy and drug injection to treat splenic injury.

PubMed

Zhang, Guoming; Sun, Yuanyuan; Yu, Jie; Dong, Lei; Mu, Nannan; Liu, Xiaohong; Liu, Lanfen; Zhang, Yan; Wang, Xiaofei; Liang, Ping

2014-01-01

The present study compares the efficacy of 915- and 2450-MHz contrast-enhanced ultrasound (CEUS)-guided percutaneous microwave coagulation with that of CEUS-guided thrombin injection for the treatment of trauma-induced spleen hemorrhage. In a canine splenic artery hemorrhage model with two levels of arterial diameter (A, <1 mm and B, between 1 and 2 mm), hemostatic therapy was performed using 915- and 2450-MHz microwaves and drug injection. Therapy efficacy was measured by comparing bleeding rate, hemostatic time, bleeding index, bleeding volume, and pathology. The most efficient technique was CEUS-guided 915-MHz percutaneous microwave coagulation therapy in terms of action time and total blood loss. The success rate of the 915-MHz microwave group was higher than that of the 2450-MHz microwave and the drug injection groups (except A level, P < 0.05). Hemostatic time, bleeding index, and bleeding volume were significantly less in the 915-MHz microwave group than those in the 2450-MHz microwave and drug injection groups (P < 0.05). Obvious degeneration and necrosis of parenchyma and large intravascular thrombosis were observed in the cavity of larger vessels in the 915-MHz microwave group, but pathologic changes of light injury could be seen in the other groups. The present study provides evidence that microwave coagulation therapy is more efficient than thrombin injection for the treatment of splenic hemorrhage. Furthermore, treatment with 915-MHz microwaves stops bleeding more rapidly and generates a wider cauterization zone than does treatment with 2450-MHz microwaves. Copyright © 2014 Elsevier Inc. All rights reserved.

Coaxial microwave electrothermal thruster performance in hydrogen

NASA Technical Reports Server (NTRS)

Richardson, W.; Asmussen, J.; Hawley, M.

1994-01-01

The microwave electro thermal thruster (MET) is an electric propulsion concept that offers the promise of high performance combined with a long lifetime. A unique feature of this electric propulsion concept is its ability to create a microwave plasma discharge separated or floating away from any electrodes or enclosing walls. This allows propellant temperatures that are higher than those in resistojets and reduces electrode and wall erosion. It has been demonstrated that microwave energy is coupled into discharges very efficiently at high input power levels. As a result of these advantages, the MET concept has been identified as a future high power electric propulsion possibility. Recently, two additional improvements have been made to the coaxial MET. The first was concerned with improving the microwave matching. Previous experiments were conducted with 10-30 percent reflected power when incident power was in excess of 600 W(exp 6). Power was reflected back to the generator because the impedance of the MET did not match the 50 ohm impedance of the microwave circuit. To solve this problem, a double stub tuning system has been inserted between the MET and the microwave power supply. The addition of the double stub tuners reduces the reflected power below 1 percent. The other improvement has prepared the coaxial MET for hydrogen experiments. To operate with hydrogen, the vacuum window which separates the coaxial line from the discharge chamber has been changed from teflon to boron nitride. All the microwave energy delivered to the plasma discharge passes through this vacuum window. This material change had caused problems in the past because of the increased microwave reflection coefficients associated with the electrical properties of boron nitride. However, by making the boron nitride window electrically one-half of a wavelength long, power reflection in the window has been eliminated. This technical note summarizes the experimental performance of the improved

Microwave Switching and Attenuation with Superconductors.

NASA Astrophysics Data System (ADS)

Poulin, Grant Darcy

1995-01-01

The discovery of high temperature superconducting (HTS) materials having a critical temperature above the boiling point of liquid nitrogen has generated a large amount of interest in both the basic and applied scientific communities. Considerable research effort has been expended in developing HTS microwave devices, since thin film, passive, microwave components will likely be the first area to be successfully commercialized. This thesis describes a new thin film HTS microwave device that can be operated as a switch or as a continuously variable attenuator. It is well suited for low power analog signal control applications and can easily be integrated with other HTS devices. Due to its small size and mass, the device is expected to find application as a receiver protection switch or as an automatic gain control element, both used in satellite communications receivers. The device has a very low insertion loss, and the isolation in the OFF state is continuously variable to 25 dB. With minor modifications, an isolation exceeding 50 dB is readily achievable. A patent application for the device has been filed, with the patent rights assigned to COM DEV. The device is based on an unusual non-linear response in HTS materials. Under a non-zero DC voltage bias, the current through a superconducting bridge is essentially voltage independent. We have proposed a thermal instability to account for this behaviour. Thermal modelling in conjunction with direct temperature measurements were used to confirm the validity of the model. We have developed a detailed model explaining the microwave response of the device. The model accurately predicts the microwave attenuation as a function of the applied DC control voltage and fully explains the device operation. A key feature is that the device acts as a pure resistive element at microwave frequencies, with no reactance. The resistance is continuously variable, controlled by the DC bias voltage. This distinguishes it from a PIN diode

Microwave Power Transmission Workshop summary

NASA Technical Reports Server (NTRS)

Freeman, J. W.

1980-01-01

The assumptions, methodologies, and conclusions of the NASA SPS studies were assessed and criticized to identify critical issues and to make recommendations for follow-on works. An assessment of the following items was made: beam forming and control, microwave amplifiers, radiating elements, and the rectenna. It was concluded that top priority should be given to determining an upper limit for permissible microwave power density which can be sent through the ionosphere.

The Microwave SQUID Multiplexer

NASA Astrophysics Data System (ADS)

Mates, John Arthur Benson

2011-12-01

This thesis describes a multiplexer of Superconducting Quantum Interference Devices (SQUIDs) with low-noise, ultra-low power dissipation, and great scalability. The multiplexer circuit measures the magnetic flux in a large number of unshunted rf SQUIDs by coupling each SQUID to a superconducting microwave resonator tuned to a unique resonance frequency and driving the resonators from a common feedline. A superposition of microwave tones measures each SQUID simultaneously using only two coaxial cables between the cryogenic device and room temperature. This multiplexer will enable the instrumentation of arrays with hundreds of thousands of low-temperature detectors for new applications in cosmology, materials analysis, and nuclear non-proliferation. The driving application of the Microwave SQUID Multiplexer is the readout of large arrays of superconducting transition-edge sensors, by some figures of merit the most sensitive detectors of electromagnetic signals over a span of more than nine orders of magnitude in energy, from 40 GHz microwaves to 200 keV gamma rays. Modern transition-edge sensors have noise-equivalent power as low as 10-20 W / Hz1/2 and energy resolution as good as 2 eV at 6 keV. These per-pixel sensitivities approach theoretical limits set by the underlying signals, motivating a rapid increase in pixel count to access new science. Compelling applications, like the non-destructive assay of nuclear material for treaty verification or the search for primordial gravity waves from inflation use arrays of these detectors to increase collection area or tile a focal plane. We developed three generations of SQUID multiplexers, optimizing the first for flux noise 0.17 muPhi0 / Hz1/2, the second for input current noise 19 pA / Hz1/2, and the last for practical multiplexing of large arrays of cosmic microwave background polarimeters based on transition-edge sensors. Using the last design we demonstrated multiplexed readout of prototype polarimeters with the

DSS 13 phase 2 pedestal room microwave layout

NASA Technical Reports Server (NTRS)

Cwik, T.; Chen, J. C.

1991-01-01

The design and predicted performance is described of the microwave layout for three band operation of the beam waveguide antenna Deep Space Station 13. Three pedestal room microwave candidate layout designs were produced for simultaneous X/S and X/Ka band operation. One of the three designs was chosen based on given constraints, and for this design the microwave performance was estimated.

Endothelium Preserving Microwave Treatment for Atherosclerosis

NASA Technical Reports Server (NTRS)

Fink, Patrick; Arndt, G. D.; Ngo, Phong

2003-01-01

This slide presentation reviews the use of microwave technology for treating Atherosclerosis while preserving the endothelium. The system uses catheter antennas as part of the system that is intended to treat atherosclerosis. The concept is to use a microwave catheter for heating the atherosclerotic lesions, and reduce constriction in the artery.

Microwave-Assisted Synthesis of "N"-Phenylsuccinimide

ERIC Educational Resources Information Center

Shell, Thomas A.; Shell, Jennifer R.; Poole, Kathleen A.; Guetzloff, Thomas F.

2011-01-01

A microwave-assisted synthesis of "N"-phenylsuccinimide has been developed for the second-semester organic teaching laboratory. Utilizing this procedure, "N"-phenylsuccinimide can be synthesized in moderate yields (40-60%) by heating a mixture of aniline and succinic anhydride in a domestic microwave oven for four minutes. This technique reduces…

Cosmological perturbations and noncommutative tachyon inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Daojun; Li Xinzhou

2004-12-15

The motivation for studying the rolling tachyon and noncommutative inflation comes from string theory. In the tachyon inflation scenario, metric perturbations are created by tachyon field fluctuations during inflation. We drive the exact mode equation for scalar perturbations of the metric and investigate the cosmological perturbations in the commutative and noncommutative inflationary spacetime driven by the tachyon field which have a Born-Infeld Lagrangian. Although at lowest order the predictions of tachyon inflation are no different than those from standard slow-roll inflation, due to the modified inflationary dynamics there exists modifications to the power spectra of fluctuations generated during inflation. Inmore » the noncommutative tachyon inflation scenario, the stringy noncommutativity of spacetime results in corrections to the primordial power spectrum that lead to a spectral index that is greater than 1 on large scales and less than 1 on small scales as the first-year results of the Wilkinson Microwave Anisotropy Probe indicate.« less

Continuous, real time microwave plasma element sensor

DOEpatents

Woskov, Paul P.; Smatlak, Donna L.; Cohn, Daniel R.; Wittle, J. Kenneth; Titus, Charles H.; Surma, Jeffrey E.

1995-01-01

Microwave-induced plasma for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury.

Continuous, real time microwave plasma element sensor

DOEpatents

Woskov, P.P.; Smatlak, D.L.; Cohn, D.R.; Wittle, J.K.; Titus, C.H.; Surma, J.E.

1995-12-26

Microwave-induced plasma is described for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury. 3 figs.

U.S. Army Research Institute Unrestricted Publications, Fiscal Year 2011

DTIC Science & Technology

2012-04-01

Alice Hirzel, Jennifer Stern, Steven Aude, Lauren Tindall, & Jeffrey E. Fite. July 2011. (ADA 546285) The Iraq and Afghanistan campaigns have...Hirzel, Jennifer Stern, Steven Aude, Lauren Tindall, & Jeffrey E. Fite. July 2011. (ADM002361 / CD-ROM) The Iraq and Afghanistan campaigns have...James P. Bliss, Steven A. Minnis, Jeffery Wilkinson, Thomas Mastaglio, & John S. Barnett. April 2011. (ADA543054) The purpose of this report is

Quantum and wave dynamical chaos in superconducting microwave billiards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietz, B., E-mail: dietz@ikp.tu-darmstadt.de; Richter, A., E-mail: richter@ikp.tu-darmstadt.de

2015-09-15

Experiments with superconducting microwave cavities have been performed in our laboratory for more than two decades. The purpose of the present article is to recapitulate some of the highlights achieved. We briefly review (i) results obtained with flat, cylindrical microwave resonators, so-called microwave billiards, concerning the universal fluctuation properties of the eigenvalues of classically chaotic systems with no, a threefold and a broken symmetry; (ii) summarize our findings concerning the wave-dynamical chaos in three-dimensional microwave cavities; (iii) present a new approach for the understanding of the phenomenon of dynamical tunneling which was developed on the basis of experiments that weremore » performed recently with unprecedented precision, and finally, (iv) give an insight into an ongoing project, where we investigate universal properties of (artificial) graphene with superconducting microwave photonic crystals that are enclosed in a microwave resonator, i.e., so-called Dirac billiards.« less

Quantum and wave dynamical chaos in superconducting microwave billiards.

PubMed

Dietz, B; Richter, A

2015-09-01

Experiments with superconducting microwave cavities have been performed in our laboratory for more than two decades. The purpose of the present article is to recapitulate some of the highlights achieved. We briefly review (i) results obtained with flat, cylindrical microwave resonators, so-called microwave billiards, concerning the universal fluctuation properties of the eigenvalues of classically chaotic systems with no, a threefold and a broken symmetry; (ii) summarize our findings concerning the wave-dynamical chaos in three-dimensional microwave cavities; (iii) present a new approach for the understanding of the phenomenon of dynamical tunneling which was developed on the basis of experiments that were performed recently with unprecedented precision, and finally, (iv) give an insight into an ongoing project, where we investigate universal properties of (artificial) graphene with superconducting microwave photonic crystals that are enclosed in a microwave resonator, i.e., so-called Dirac billiards.

Freeze-thaw durability of microwave cured air-entrained concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pheeraphan, T.; Leung, C.K.Y.

1997-03-01

The strength development of concrete can be greatly accelerated by curing with microwave energy. Microwave curing can therefore be beneficial to construction operations such as concrete precasting and repair. To provide freeze-thaw durability for infrastructure applications, air entrainment has to be introduced. In this investigation, the freeze-thaw resistance of microwave cured air-entrained concrete is measured, and compared to that of air-entrained concrete under normal curing. Their compressive strength at 14 days and air-void characteristics are also measured and compared. The test results indicate that microwave curing can impair the freeze-thaw durability of high w/c concrete but not for low w/cmore » concrete. Also, under microwave curing, the decrease in strength due to air entrainment becomes more significant. Based on these observations, it is recommended that for microwave cured air-entrained concrete, a low w/c ratio should be employed.« less

Microwave Assisted Grafting of Gums and Extraction of Natural Materials.

PubMed

Singh, Inderbir; Rani, Priya; Kumar, Pradeep

2017-01-01

Microwave assisted modification of polymers has become an established technique for modifying the functionality of polymers. Microwave irradiation reduces reaction time as well as the use of toxic solvents with enhanced sensitivity and yields of quality products. In this review article instrumentation and basic principles of microwave activation have been discussed. Microwave assisted grafting of natural gums, characterization of grafted polymers and their toxicological parameters have also been listed. Pharmaceutical applications viz. drug release retardant, mucoahesion and tablet superdisintegrant potential of microwave assisted gums has also been discussed. An overview of microwave assisted extraction of plant based natural materials has also been presented. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

ORGANIC SYNTHESES USING MICROWAVES AND SUPPORTED REAGENTS

EPA Science Inventory

Microwave-accelerated chemical syntheses under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment...

Trajectory Design for the Microwave Anisotropy Probe (MAP)

NASA Technical Reports Server (NTRS)

Newman, Lauri Kraft; Rohrbaugh, David; Bauer, Frank H. (Technical Monitor)

2001-01-01

The Microwave Anisotropy, Probe (MAP) is a Medium Class Explorers (MIDEX) Mission produced in partnership between Goddard Space Flight Center (GSFC) and Princeton University. The goal of the MAP mission is to produce an accurate fill-sky, map of the cosmic microwave background temperature fluctuations (anisotropy). The mission orbit is a Lissajous orbit about the L(sub 2) Sun-Earth Lagrange point. The trajectory design for MAP is complex, having many requirements that must be met including shadow avoidance, sun angle constraints, Lissqjous size and shape characteristics, and limited Delta-V budget. In order to find a trajectory that met the design requirements for the entire 4-year mission lifetime goal, GSFC Flight Dynamics engineers performed many analyses, the results of which are presented herein. The paper discusses the preliminary trade-offs to establish a baseline trajectory, analysis to establish the nominal daily trajectory, and the launch window determination to widen the opportunity from instantaneous to several minutes for each launch date.

Microwave processing of cement and concrete materials – towards an industrial reality?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buttress, Adam, E-mail: adam.buttress@nottingham.ac.uk; Jones, Aled; Kingman, Sam

2015-02-15

Each year a substantial body of literature is published on the use of microwave to process cement and concrete materials. Yet to date, very few if any have lead the realisation of a commercial scale industrial system and is the context under which this review has been undertaken. The state-of the–art is evaluated for opportunities, and the key barriers to the development of new microwave-based processing techniques to enhance production, processing and recycling of cement and concrete materials. Applications reviewed include pyro-processing of cement clinker; accelerated curing, non-destructive testing and evaluation (NDT&E), and end-of-life processing including radionuclide decontamination.

Optimized ECR plasma apparatus with varied microwave window thickness