Institution
Raytheon
Company•Waltham, Massachusetts, United States•
About: Raytheon is a company organization based out in Waltham, Massachusetts, United States. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 15290 authors who have published 18973 publications receiving 300052 citations.
Topics: Signal, Antenna (radio), Radar, Layer (electronics), Turbine
Papers published on a yearly basis
Papers
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TL;DR: In this article, the detection probability PD of a radar receiver which postdetection integrates N pulses of an expqnentially correlated signal from a Rayleigh target in thermal noise is determined.
Abstract: The detection probability PD of a radar receiver which postdetection integrates N pulses of an expqnentially correlated signal from a Rayleigh target in thermal noise is determined. At the limiting correlation coefficients, p = 1 and p = 0, the analysis yields, respectively, the well known Swerling case 1 and case 2 formulas. The effect of partial (0 ? p ? 1) correlation is exhibited in a set of curves of PD versus signal-to-noise ratio, X, for various N and p. Additional curves compare the exact fluctuation loss determined from the above analysis with an approximate expression universally employed by radar system engineers.
61 citations
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TL;DR: Using maximum entropy power spectral estimation, the estimate of the frequency of a sinusoid in white noise has been shown to be very sensitive to the initial sinusoidal phase as discussed by the authors, which can be reduced by replacing the real data by its analytic form, reducing the sampling rate by two, and employing the power spectral estimate for complex data.
Abstract: Using maximum entropy power spectral estimation, the estimate of the frequency of a sinusoid in white noise has been shown to be very sensitive to the initial sinusoidal phase. This phase dependence can be significantly reduced by replacing the real data by its analytic form, reducing the sampling rate by two, and employing the power spectral estimate for complex data.
61 citations
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TL;DR: In this article, the authors used the ingress and egress times obtained from the observed limb diffraction effects together with the best ephemerides available for the orbiter and the planet to determine the surface elevations at the occultation points relative to the reference areoid.
Abstract: Radio occultation measurements were made at approximately 50 locations on Mars with the Viking Orbiter 1 S (2.3 GHz) and X (8.4 GHz) band tracking links during October 1976. The measurements have been used to study the topography and atmosphere of Mars at latitudes ranging from about 75 deg S to 70 deg N. By using the ingress and egress times obtained from the observed limb diffraction effects together with the best ephemerides available for the orbiter and the planet we have determined the surface elevations at the occultation points relative to the reference areoid. The observations agree with Mariner 9 and radar data to within 2 km. The mean atmospheric pressure at the areoid level was found to be 5.9 mbar during the northern midsummer season, a value which agrees quite well with data obtained at the landing sites. By comparing the new electron density measurements with earlier Mariner data we have determined that the temperature and the plasma scale height of the upper atmosphere appear to be functions of solar activity.
61 citations
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TL;DR: In this article, the authors proposed spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption coefficient (R2 = 0.98 and p < 0.01).
Abstract: During clinical studies, thermoacoustic imaging (TAI) failed to reliably identify malignant breast tissue. To increase detection capability, we propose spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption. Phantoms composed of different ratios of water and fat were imaged using excitation frequencies between 2.7 and 3.1 GHz. The frequency-dependent slope of the TA signal was highly correlated with that of its absorption coefficient (R2 = 0.98 and p < 0.01), indicating spectroscopic TAI can distinguish materials based on their intrinsic dielectric properties. This approach potentially enhances cancer detection due to the increased water content of many tumors.
61 citations
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TL;DR: In this paper, temperature and ternary composition for coexisting liquid and crystalline phases on the air isobar in the system Fe2O3-Fe3O4-YFeO3 with particular regard to the stability range and compositional limits of yttrium iron garnet were determined by conventional quenching techniques combined with measurements of loss in weight at the reaction temperature.
Abstract: Measurements were made of temperature and ternary composition for coexisting liquid and crystalline phases on the air isobar in the system Fe2O3-Fe3O4-YFeO3 with particular regard to the stability range and compositional limits of yttrium iron garnet. Phase equilibrium relations were determined by conventional quenching techniques combined with measurements of loss in weight at the reaction temperature to locate true ternary compositions. The intersection of the air isobar with the ternary univariant boundary curve for coexisting magnetite, garnet, and liquid phases results in a eutectic-type situation at the composition Y0.27Fe1.73 O2.87 and 1469°± 2°C. A similar intersection of the isobar with the boundary curve for coexisting garnet, orthoferrite, and liquid phases gives rise to a peritectic-type reaction at 1555° 3°C. and Y0.44Fe1.56 O2.89 The yttrium iron garnet crystallizing from liquids within these temperature and composition limits contains up to 0.5 mole % iron oxide in excess of the stoichiometric formula in terms of the starting composition 37.5 mole % Y2O3, 62.5 mole % Fe2O3. At 1470° C. the garnet phase in equilibrium with oxide liquid contains 2 mole % FeO in solid solution. The small solubility of excess of iron oxide and partial reduction of the garnet phase in air are unavoidable during equilibrium growth from the melt.
61 citations
Authors
Showing all 15293 results
Name | H-index | Papers | Citations |
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Peter J. Kahrilas | 109 | 586 | 46064 |
Edward J. Wollack | 104 | 732 | 102070 |
Duong Nguyen | 98 | 674 | 47332 |
Miroslav Krstic | 95 | 955 | 42886 |
Steven L. Suib | 89 | 862 | 34189 |
Gabriel M. Rebeiz | 87 | 806 | 32443 |
Charles W. Engelbracht | 83 | 210 | 28137 |
Paul A. Grayburn | 77 | 397 | 26880 |
Eric J. Huang | 72 | 201 | 22172 |
Thomas F. Eck | 72 | 150 | 32965 |
David M. Margolis | 70 | 227 | 17314 |
David W. T. Griffith | 65 | 288 | 14232 |
Gerhard Klimeck | 65 | 685 | 18447 |
Nickolay A. Krotkov | 63 | 219 | 11250 |
Olaf Stüve | 63 | 290 | 14268 |